Optical Signatures of Coupled Quantum Dots

DTIC Science & Technology

2006-02-03

Optical Signatures of Coupled Quantum Dots E. A. Stinaff,1 M. Scheibner,1 A. S . Bracker,1 I. V. Ponomarev,1 V. L. Korenev ,2 M. E. Ware,1 M. F. Doty,1...possibility of optically coupling quantum dots for application in quantum information processing. S emiconductor approaches to quantum information can...REPORTS 3 FEBRUARY 2006 VOL 311 SCIENCE www.sciencemag.org636 o n A ug us t 1 4, 2 00 7 w w w . s ci en ce m ag .o rg D ow nl oa de d fr om Report

Metasurface-Enabled Remote Quantum Interference.

PubMed

Jha, Pankaj K; Ni, Xingjie; Wu, Chihhui; Wang, Yuan; Zhang, Xiang

2015-07-10

An anisotropic quantum vacuum (AQV) opens novel pathways for controlling light-matter interaction in quantum optics, condensed matter physics, etc. Here, we theoretically demonstrate a strong AQV over macroscopic distances enabled by a judiciously designed array of subwavelength-scale nanoantennas-a metasurface. We harness the phase-control ability and the polarization-dependent response of the metasurface to achieve strong anisotropy in the decay rate of a quantum emitter located over distances of hundreds of wavelengths. Such an AQV induces quantum interference among radiative decay channels in an atom with orthogonal transitions. Quantum vacuum engineering with metasurfaces holds promise for exploring new paradigms of long-range light-matter interaction for atom optics, solid-state quantum optics, quantum information processing, etc.

No-go theorem for passive single-rail linear optical quantum computing.

PubMed

Wu, Lian-Ao; Walther, Philip; Lidar, Daniel A

2013-01-01

Photonic quantum systems are among the most promising architectures for quantum computers. It is well known that for dual-rail photons effective non-linearities and near-deterministic non-trivial two-qubit gates can be achieved via the measurement process and by introducing ancillary photons. While in principle this opens a legitimate path to scalable linear optical quantum computing, the technical requirements are still very challenging and thus other optical encodings are being actively investigated. One of the alternatives is to use single-rail encoded photons, where entangled states can be deterministically generated. Here we prove that even for such systems universal optical quantum computing using only passive optical elements such as beam splitters and phase shifters is not possible. This no-go theorem proves that photon bunching cannot be passively suppressed even when extra ancilla modes and arbitrary number of photons are used. Our result provides useful guidance for the design of optical quantum computers.

Quantum interference between transverse spatial waveguide modes.

PubMed

Mohanty, Aseema; Zhang, Mian; Dutt, Avik; Ramelow, Sven; Nussenzveig, Paulo; Lipson, Michal

2017-01-20

Integrated quantum optics has the potential to markedly reduce the footprint and resource requirements of quantum information processing systems, but its practical implementation demands broader utilization of the available degrees of freedom within the optical field. To date, integrated photonic quantum systems have primarily relied on path encoding. However, in the classical regime, the transverse spatial modes of a multi-mode waveguide have been easily manipulated using the waveguide geometry to densely encode information. Here, we demonstrate quantum interference between the transverse spatial modes within a single multi-mode waveguide using quantum circuit-building blocks. This work shows that spatial modes can be controlled to an unprecedented level and have the potential to enable practical and robust quantum information processing.

Quantum state transfer through time reversal of an optical channel

NASA Astrophysics Data System (ADS)

Hush, M. R.; Bentley, C. D. B.; Ahlefeldt, R. L.; James, M. R.; Sellars, M. J.; Ugrinovskii, V.

2016-12-01

Rare-earth ions have exceptionally long coherence times, making them an excellent candidate for quantum information processing. A key part of this processing is quantum state transfer. We show that perfect state transfer can be achieved by time reversing the intermediate quantum channel, and suggest using a gradient echo memory (GEM) to perform this time reversal. We propose an experiment with rare-earth ions to verify these predictions, where an emitter and receiver crystal are connected with an optical channel passed through a GEM. We investigate the effect experimental imperfections and collective dynamics have on the state transfer process. We demonstrate that super-radiant effects can enhance coupling into the optical channel and improve the transfer fidelity. We lastly discuss how our results apply to state transfer of entangled states.

Universal Linear Optics: An implementation of Boson Sampling on a Fully Reconfigurable Circuit

NASA Astrophysics Data System (ADS)

Harrold, Christopher; Carolan, Jacques; Sparrow, Chris; Russell, Nicholas J.; Silverstone, Joshua W.; Marshall, Graham D.; Thompson, Mark G.; Matthews, Jonathan C. F.; O'Brien, Jeremy L.; Laing, Anthony; Martín-López, Enrique; Shadbolt, Peter J.; Matsuda, Nobuyuki; Oguma, Manabu; Itoh, Mikitaka; Hashimoto, Toshikazu

Linear optics has paved the way for fundamental tests in quantum mechanics and has gone on to enable a broad range of quantum information processing applications for quantum technologies. We demonstrate an integrated photonics processor that is universal for linear optics. The device is a silica-on-silicon planar waveguide circuit (PLC) comprising a cascade of 15 Mach Zehnder interferometers, with 30 directional couplers and 30 tunable thermo-optic phase shifters which are electrically interfaced for the arbitrary setting of a phase. We input ensembles of up to six photons, and monitor the output with a 12-single-photon detector system. The calibrated device is capable of implementing any linear optical protocol. This enables the implementation of new quantum information processing tasks in seconds, which would have previously taken months to realise. We demonstrate 100 instances of the boson sampling problem with verification tests, and six-dimensional complex Hadamards. Also Imperial College London.

Ultrafast optical control of individual quantum dot spin qubits.

PubMed

De Greve, Kristiaan; Press, David; McMahon, Peter L; Yamamoto, Yoshihisa

2013-09-01

Single spins in semiconductor quantum dots form a promising platform for solid-state quantum information processing. The spin-up and spin-down states of a single electron or hole, trapped inside a quantum dot, can represent a single qubit with a reasonably long decoherence time. The spin qubit can be optically coupled to excited (charged exciton) states that are also trapped in the quantum dot, which provides a mechanism to quickly initialize, manipulate and measure the spin state with optical pulses, and to interface between a stationary matter qubit and a 'flying' photonic qubit for quantum communication and distributed quantum information processing. The interaction of the spin qubit with light may be enhanced by placing the quantum dot inside a monolithic microcavity. An entire system, consisting of a two-dimensional array of quantum dots and a planar microcavity, may plausibly be constructed by modern semiconductor nano-fabrication technology and could offer a path toward chip-sized scalable quantum repeaters and quantum computers. This article reviews the recent experimental developments in optical control of single quantum dot spins for quantum information processing. We highlight demonstrations of a complete set of all-optical single-qubit operations on a single quantum dot spin: initialization, an arbitrary SU(2) gate, and measurement. We review the decoherence and dephasing mechanisms due to hyperfine interaction with the nuclear-spin bath, and show how the single-qubit operations can be combined to perform spin echo sequences that extend the qubit decoherence from a few nanoseconds to several microseconds, more than 5 orders of magnitude longer than the single-qubit gate time. Two-qubit coupling is discussed, both within a single chip by means of exchange coupling of nearby spins and optically induced geometric phases, as well as over longer-distances. Long-distance spin-spin entanglement can be generated if each spin can emit a photon that is entangled with the spin, and these photons are then interfered. We review recent work demonstrating entanglement between a stationary spin qubit and a flying photonic qubit. These experiments utilize the polarization- and frequency-dependent spontaneous emission from the lowest charged exciton state to single spin Zeeman sublevels.

High-Dimensional Quantum Information Processing with Linear Optics

NASA Astrophysics Data System (ADS)

Fitzpatrick, Casey A.

Quantum information processing (QIP) is an interdisciplinary field concerned with the development of computers and information processing systems that utilize quantum mechanical properties of nature to carry out their function. QIP systems have become vastly more practical since the turn of the century. Today, QIP applications span imaging, cryptographic security, computation, and simulation (quantum systems that mimic other quantum systems). Many important strategies improve quantum versions of classical information system hardware, such as single photon detectors and quantum repeaters. Another more abstract strategy engineers high-dimensional quantum state spaces, so that each successful event carries more information than traditional two-level systems allow. Photonic states in particular bring the added advantages of weak environmental coupling and data transmission near the speed of light, allowing for simpler control and lower system design complexity. In this dissertation, numerous novel, scalable designs for practical high-dimensional linear-optical QIP systems are presented. First, a correlated photon imaging scheme using orbital angular momentum (OAM) states to detect rotational symmetries in objects using measurements, as well as building images out of those interactions is reported. Then, a statistical detection method using chains of OAM superpositions distributed according to the Fibonacci sequence is established and expanded upon. It is shown that the approach gives rise to schemes for sorting, detecting, and generating the recursively defined high-dimensional states on which some quantum cryptographic protocols depend. Finally, an ongoing study based on a generalization of the standard optical multiport for applications in quantum computation and simulation is reported upon. The architecture allows photons to reverse momentum inside the device. This in turn enables realistic implementation of controllable linear-optical scattering vertices for carrying out quantum walks on arbitrary graph structures, a powerful tool for any quantum computer. It is shown that the novel architecture provides new, efficient capabilities for the optical quantum simulation of Hamiltonians and topologically protected states. Further, these simulations use exponentially fewer resources than feedforward techniques, scale linearly to higher-dimensional systems, and use only linear optics, thus offering a concrete experimentally achievable implementation of graphical models of discrete-time quantum systems.

Markovian and non-Markovian light-emission channels in strained quantum wires.

PubMed

Lopez-Richard, V; González, J C; Matinaga, F M; Trallero-Giner, C; Ribeiro, E; Sousa Dias, M Rebello; Villegas-Lelovsky, L; Marques, G E

2009-09-01

We have achieved conditions to obtain optical memory effects in semiconductor nanostructures. The system is based on strained InP quantum wires where the tuning of the heavy-light valence band splitting has allowed the existence of two independent optical channels with correlated and uncorrelated excitation and light-emission processes. The presence of an optical channel that preserves the excitation memory is unambiguously corroborated by photoluminescence measurements of free-standing quantum wires under different configurations of the incoming and outgoing light polarizations in various samples. High-resolution transmission electron microscopy and electron diffraction indicate the presence of strain effects in the optical response. By using this effect and under certain growth conditions, we have shown that the optical recombination is mediated by relaxation processes with different natures: one a Markov and another with a non-Markovian signature. Resonance intersubband light-heavy hole transitions assisted by optical phonons provide the desired mechanism for the correlated non-Markovian carrier relaxation process. A multiband calculation for strained InP quantum wires was developed to account for the description of the character of the valence band states and gives quantitative support for light hole-heavy hole transitions assisted by optical phonons.

Nonlinear optical properties and supercontinuum spectrum of titania-modified carbon quantum dots

NASA Astrophysics Data System (ADS)

Kulchin, Yu N.; Mayor, A. Yu; Proschenko, D. Yu; Postnova, I. V.; Shchipunov, Yu A.

2016-04-01

We have studied the nonlinear optical properties and supercontinuum spectrum of solutions of carbon quantum dots prepared by a hydrothermal process from chitin and then coated with titania. The titania coating has been shown to have an activating effect on the carbon quantum dots, enhancing supercontinuum generation in the blue-violet spectral region and enabling their nonlinear optical characteristics to be varied.

Coherent spin control of a nanocavity-enhanced qubit in diamond

DOE PAGES

Li, Luozhou; Lu, Ming; Schroder, Tim; ...

2015-01-28

A central aim of quantum information processing is the efficient entanglement of multiple stationary quantum memories via photons. Among solid-state systems, the nitrogen-vacancy centre in diamond has emerged as an excellent optically addressable memory with second-scale electron spin coherence times. Recently, quantum entanglement and teleportation have been shown between two nitrogen-vacancy memories, but scaling to larger networks requires more efficient spin-photon interfaces such as optical resonators. Here we report such nitrogen-vacancy nanocavity systems in strong Purcell regime with optical quality factors approaching 10,000 and electron spin coherence times exceeding 200 µs using a silicon hard-mask fabrication process. This spin-photon interfacemore » is integrated with on-chip microwave striplines for coherent spin control, providing an efficient quantum memory for quantum networks.« less

Fine structure and optical pumping of spins in individual semiconductor quantum dots

NASA Astrophysics Data System (ADS)

Bracker, Allan S.; Gammon, Daniel; Korenev, Vladimir L.

2008-11-01

We review spin properties of semiconductor quantum dots and their effect on optical spectra. Photoluminescence and other types of spectroscopy are used to probe neutral and charged excitons in individual quantum dots with high spectral and spatial resolution. Spectral fine structure and polarization reveal how quantum dot spins interact with each other and with their environment. By taking advantage of the selectivity of optical selection rules and spin relaxation, optical spin pumping of the ground state electron and nuclear spins is achieved. Through such mechanisms, light can be used to process spins for use as a carrier of information.

Silica-on-silicon waveguide quantum circuits.

PubMed

Politi, Alberto; Cryan, Martin J; Rarity, John G; Yu, Siyuan; O'Brien, Jeremy L

2008-05-02

Quantum technologies based on photons will likely require an integrated optics architecture for improved performance, miniaturization, and scalability. We demonstrate high-fidelity silica-on-silicon integrated optical realizations of key quantum photonic circuits, including two-photon quantum interference with a visibility of 94.8 +/- 0.5%; a controlled-NOT gate with an average logical basis fidelity of 94.3 +/- 0.2%; and a path-entangled state of two photons with fidelity of >92%. These results show that it is possible to directly "write" sophisticated photonic quantum circuits onto a silicon chip, which will be of benefit to future quantum technologies based on photons, including information processing, communication, metrology, and lithography, as well as the fundamental science of quantum optics.

Quantum memories: emerging applications and recent advances

NASA Astrophysics Data System (ADS)

Heshami, Khabat; England, Duncan G.; Humphreys, Peter C.; Bustard, Philip J.; Acosta, Victor M.; Nunn, Joshua; Sussman, Benjamin J.

2016-11-01

Quantum light-matter interfaces are at the heart of photonic quantum technologies. Quantum memories for photons, where non-classical states of photons are mapped onto stationary matter states and preserved for subsequent retrieval, are technical realizations enabled by exquisite control over interactions between light and matter. The ability of quantum memories to synchronize probabilistic events makes them a key component in quantum repeaters and quantum computation based on linear optics. This critical feature has motivated many groups to dedicate theoretical and experimental research to develop quantum memory devices. In recent years, exciting new applications, and more advanced developments of quantum memories, have proliferated. In this review, we outline some of the emerging applications of quantum memories in optical signal processing, quantum computation and non-linear optics. We review recent experimental and theoretical developments, and their impacts on more advanced photonic quantum technologies based on quantum memories.

Quantum memories: emerging applications and recent advances.

PubMed

Heshami, Khabat; England, Duncan G; Humphreys, Peter C; Bustard, Philip J; Acosta, Victor M; Nunn, Joshua; Sussman, Benjamin J

2016-11-12

Quantum light-matter interfaces are at the heart of photonic quantum technologies. Quantum memories for photons, where non-classical states of photons are mapped onto stationary matter states and preserved for subsequent retrieval, are technical realizations enabled by exquisite control over interactions between light and matter. The ability of quantum memories to synchronize probabilistic events makes them a key component in quantum repeaters and quantum computation based on linear optics. This critical feature has motivated many groups to dedicate theoretical and experimental research to develop quantum memory devices. In recent years, exciting new applications, and more advanced developments of quantum memories, have proliferated. In this review, we outline some of the emerging applications of quantum memories in optical signal processing, quantum computation and non-linear optics. We review recent experimental and theoretical developments, and their impacts on more advanced photonic quantum technologies based on quantum memories.

Quantum memories: emerging applications and recent advances

PubMed Central

Heshami, Khabat; England, Duncan G.; Humphreys, Peter C.; Bustard, Philip J.; Acosta, Victor M.; Nunn, Joshua; Sussman, Benjamin J.

2016-01-01

Quantum light–matter interfaces are at the heart of photonic quantum technologies. Quantum memories for photons, where non-classical states of photons are mapped onto stationary matter states and preserved for subsequent retrieval, are technical realizations enabled by exquisite control over interactions between light and matter. The ability of quantum memories to synchronize probabilistic events makes them a key component in quantum repeaters and quantum computation based on linear optics. This critical feature has motivated many groups to dedicate theoretical and experimental research to develop quantum memory devices. In recent years, exciting new applications, and more advanced developments of quantum memories, have proliferated. In this review, we outline some of the emerging applications of quantum memories in optical signal processing, quantum computation and non-linear optics. We review recent experimental and theoretical developments, and their impacts on more advanced photonic quantum technologies based on quantum memories. PMID:27695198

Chiral quantum optics.

PubMed

Lodahl, Peter; Mahmoodian, Sahand; Stobbe, Søren; Rauschenbeutel, Arno; Schneeweiss, Philipp; Volz, Jürgen; Pichler, Hannes; Zoller, Peter

2017-01-25

Advanced photonic nanostructures are currently revolutionizing the optics and photonics that underpin applications ranging from light technology to quantum-information processing. The strong light confinement in these structures can lock the local polarization of the light to its propagation direction, leading to propagation-direction-dependent emission, scattering and absorption of photons by quantum emitters. The possibility of such a propagation-direction-dependent, or chiral, light-matter interaction is not accounted for in standard quantum optics and its recent discovery brought about the research field of chiral quantum optics. The latter offers fundamentally new functionalities and applications: it enables the assembly of non-reciprocal single-photon devices that can be operated in a quantum superposition of two or more of their operational states and the realization of deterministic spin-photon interfaces. Moreover, engineered directional photonic reservoirs could lead to the development of complex quantum networks that, for example, could simulate novel classes of quantum many-body systems.

Universal quantum gates on electron-spin qubits with quantum dots inside single-side optical microcavities.

PubMed

Wei, Hai-Rui; Deng, Fu-Guo

2014-01-13

We present some compact quantum circuits for a deterministic quantum computing on electron-spin qubits assisted by quantum dots inside single-side optical microcavities, including the CNOT, Toffoli, and Fredkin gates. They are constructed by exploiting the giant optical Faraday rotation induced by a single-electron spin in a quantum dot inside a single-side optical microcavity as a result of cavity quantum electrodynamics. Our universal quantum gates have some advantages. First, all the gates are accomplished with a success probability of 100% in principle. Second, our schemes require no additional electron-spin qubits and they are achieved by some input-output processes of a single photon. Third, our circuits for these gates are simple and economic. Moreover, our devices for these gates work in both the weak coupling and the strong coupling regimes, and they are feasible in experiment.

Scalable photonic quantum computing assisted by quantum-dot spin in double-sided optical microcavity.

PubMed

Wei, Hai-Rui; Deng, Fu-Guo

2013-07-29

We investigate the possibility of achieving scalable photonic quantum computing by the giant optical circular birefringence induced by a quantum-dot spin in a double-sided optical microcavity as a result of cavity quantum electrodynamics. We construct a deterministic controlled-not gate on two photonic qubits by two single-photon input-output processes and the readout on an electron-medium spin confined in an optical resonant microcavity. This idea could be applied to multi-qubit gates on photonic qubits and we give the quantum circuit for a three-photon Toffoli gate. High fidelities and high efficiencies could be achieved when the side leakage to the cavity loss rate is low. It is worth pointing out that our devices work in both the strong and the weak coupling regimes.

Optically induced excitonic electroabsorption in a periodically delta-doped InGaAs/GaAs multiple quantum well structure

NASA Technical Reports Server (NTRS)

Larsson, A.; Maserjian, J.

1991-01-01

Large optically induced Stark shifts have been observed in a periodically delta-doped InGaAs/GaAs multiple quantum well structure. With an excitation intensity of 10 mW/sq cm, an absolute quantum well absorption change of 7000/cm was measured with a corresponding differential absorption change as high as 80 percent. The associated maximum change in the quantum well refractive index is 0.04. This material is promising for device development for all-optical computing and signal processing.

Optical communication with two-photon coherent stages. I - Quantum-state propagation and quantum-noise reduction

NASA Technical Reports Server (NTRS)

Yuen, H. P.; Shapiro, J. H.

1978-01-01

To determine the ultimate performance limitations imposed by quantum effects, it is also essential to consider optimum quantum-state generation. Certain 'generalized' coherent states of the radiation field possess novel quantum noise characteristics that offer the potential for greatly improved optical communications. These states have been called two-photon coherent states because they can be generated, in principle, by stimulated two-photon processes. The use of two-photon coherent state (TCS) radiation in free-space optical communications is considered. A simple theory of quantum state propagation is developed. The theory provides the basis for representing the free-space channel in a quantum-mechanical form convenient for communication analysis. The new theory is applied to TCS radiation.

Integrated-optics heralded controlled-NOT gate for polarization-encoded qubits

NASA Astrophysics Data System (ADS)

Zeuner, Jonas; Sharma, Aditya N.; Tillmann, Max; Heilmann, René; Gräfe, Markus; Moqanaki, Amir; Szameit, Alexander; Walther, Philip

2018-03-01

Recent progress in integrated-optics technology has made photonics a promising platform for quantum networks and quantum computation protocols. Integrated optical circuits are characterized by small device footprints and unrivalled intrinsic interferometric stability. Here, we take advantage of femtosecond-laser-written waveguides' ability to process polarization-encoded qubits and present an implementation of a heralded controlled-NOT gate on chip. We evaluate the gate performance in the computational basis and a superposition basis, showing that the gate can create polarization entanglement between two photons. Transmission through the integrated device is optimized using thermally expanded core fibers and adiabatically reduced mode-field diameters at the waveguide facets. This demonstration underlines the feasibility of integrated quantum gates for all-optical quantum networks and quantum repeaters.

Layered Architectures for Quantum Computers and Quantum Repeaters

NASA Astrophysics Data System (ADS)

Jones, Nathan C.

This chapter examines how to organize quantum computers and repeaters using a systematic framework known as layered architecture, where machine control is organized in layers associated with specialized tasks. The framework is flexible and could be used for analysis and comparison of quantum information systems. To demonstrate the design principles in practice, we develop architectures for quantum computers and quantum repeaters based on optically controlled quantum dots, showing how a myriad of technologies must operate synchronously to achieve fault-tolerance. Optical control makes information processing in this system very fast, scalable to large problem sizes, and extendable to quantum communication.

Thermooptic two-mode interference device for reconfigurable quantum optic circuits

NASA Astrophysics Data System (ADS)

Sahu, Partha Pratim

2018-06-01

Reconfigurable large-scale integrated quantum optic circuits require compact component having capability of accurate manipulation of quantum entanglement for quantum communication and information processing applications. Here, a thermooptic two-mode interference coupler has been introduced as a compact component for generation of reconfigurable complex multi-photons quantum interference. Both theoretical and experimental approaches are used for the demonstration of two-photon and four-photon quantum entanglement manipulated with thermooptic phase change in TMI region. Our results demonstrate complex multi-photon quantum interference with high fabrication tolerance and quantum fidelity in smaller dimension than previous thermooptic Mach-Zehnder implementations.

III-V quantum light source and cavity-QED on silicon.

PubMed

Luxmoore, I J; Toro, R; Del Pozo-Zamudio, O; Wasley, N A; Chekhovich, E A; Sanchez, A M; Beanland, R; Fox, A M; Skolnick, M S; Liu, H Y; Tartakovskii, A I

2013-01-01

Non-classical light sources offer a myriad of possibilities in both fundamental science and commercial applications. Single photons are the most robust carriers of quantum information and can be exploited for linear optics quantum information processing. Scale-up requires miniaturisation of the waveguide circuit and multiple single photon sources. Silicon photonics, driven by the incentive of optical interconnects is a highly promising platform for the passive optical components, but integrated light sources are limited by silicon's indirect band-gap. III-V semiconductor quantum-dots, on the other hand, are proven quantum emitters. Here we demonstrate single-photon emission from quantum-dots coupled to photonic crystal nanocavities fabricated from III-V material grown directly on silicon substrates. The high quality of the III-V material and photonic structures is emphasized by observation of the strong-coupling regime. This work opens-up the advantages of silicon photonics to the integration and scale-up of solid-state quantum optical systems.

An on-chip coupled resonator optical waveguide single-photon buffer

PubMed Central

Takesue, Hiroki; Matsuda, Nobuyuki; Kuramochi, Eiichi; Munro, William J.; Notomi, Masaya

2013-01-01

Integrated quantum optical circuits are now seen as one of the most promising approaches with which to realize single-photon quantum information processing. Many of the core elements for such circuits have been realized, including sources, gates and detectors. However, a significant missing function necessary for photonic quantum information processing on-chip is a buffer, where single photons are stored for a short period of time to facilitate circuit synchronization. Here we report an on-chip single-photon buffer based on coupled resonator optical waveguides (CROW) consisting of 400 high-Q photonic crystal line-defect nanocavities. By using the CROW, a pulsed single photon is successfully buffered for 150 ps with 50-ps tunability while maintaining its non-classical properties. Furthermore, we show that our buffer preserves entanglement by storing and retrieving one photon from a time-bin entangled state. This is a significant step towards an all-optical integrated quantum information processor. PMID:24217422

Photonic Quantum Networks formed from NV− centers

PubMed Central

Nemoto, Kae; Trupke, Michael; Devitt, Simon J.; Scharfenberger, Burkhard; Buczak, Kathrin; Schmiedmayer, Jörg; Munro, William J.

2016-01-01

In this article we present a simple repeater scheme based on the negatively-charged nitrogen vacancy centre in diamond. Each repeater node is built from modules comprising an optical cavity containing a single NV−, with one nuclear spin from 15N as quantum memory. The module uses only deterministic processes and interactions to achieve high fidelity operations (>99%), and modules are connected by optical fiber. In the repeater node architecture, the processes between modules by photons can be in principle deterministic, however current limitations on optical components lead the processes to be probabilistic but heralded. Our resource-modest repeater architecture contains two modules at each node, and the repeater nodes are then connected by entangled photon pairs. We discuss the performance of such a quantum repeater network with modest resources and then incorporate more resource-intense strategies step by step. Our architecture should allow large-scale quantum information networks with existing or near future technology. PMID:27215433

Photonic Quantum Networks formed from NV(-) centers.

PubMed

Nemoto, Kae; Trupke, Michael; Devitt, Simon J; Scharfenberger, Burkhard; Buczak, Kathrin; Schmiedmayer, Jörg; Munro, William J

2016-05-24

In this article we present a simple repeater scheme based on the negatively-charged nitrogen vacancy centre in diamond. Each repeater node is built from modules comprising an optical cavity containing a single NV(-), with one nuclear spin from (15)N as quantum memory. The module uses only deterministic processes and interactions to achieve high fidelity operations (>99%), and modules are connected by optical fiber. In the repeater node architecture, the processes between modules by photons can be in principle deterministic, however current limitations on optical components lead the processes to be probabilistic but heralded. Our resource-modest repeater architecture contains two modules at each node, and the repeater nodes are then connected by entangled photon pairs. We discuss the performance of such a quantum repeater network with modest resources and then incorporate more resource-intense strategies step by step. Our architecture should allow large-scale quantum information networks with existing or near future technology.

Control of optical bistability and third-order nonlinearity via tunneling induced quantum interference in triangular quantum dot molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Si-Cong, E-mail: tiansicong@ciomp.ac.cn; Tong, Cun-Zhu, E-mail: tongcz@ciomp.ac.cn; Zhang, Jin-Long

The optical bistability of a triangular quantum dot molecules embedded inside a unidirectional ring cavity is studied. The type, the threshold and the hysteresis loop of the optical bistability curves can be modified by the tunneling parameters, as well as the probe laser field. The linear and nonlinear susceptibilities of the medium are also studied to interpret the corresponding results. The physical interpretation is that the tunneling can induce the quantum interference, which modifies the linear and the nonlinear response of the medium. As a consequence, the characteristics of the optical bistability are changed. The scheme proposed here can bemore » utilized for optimizing and controlling the optical switching process.« less

Novel optoelectronic devices; Proceedings of the Meeting, The Hague, Netherlands, Mar. 31-Apr. 2, 1987

NASA Technical Reports Server (NTRS)

Adams, Michael J. (Editor)

1987-01-01

The present conference on novel optoelectronics discusses topics in the state-of-the-art in this field in the Netherlands, quantum wells, integrated optics, nonlinear optical devices and fiber-optic-based devices, ultrafast optics, and nonlinear optics and optical bistability. Attention is given to the production of fiber-optics for telecommunications by means of PCVD, lifetime broadening in quantum wells, nonlinear multiple quantum well waveguide devices, tunable single-wavelength lasers, an Si integrated waveguiding polarimeter, and an electrooptic light modulator using long-range surface plasmons. Also discussed are backward-wave couplers and reflectors, a wavelength-selective all-fiber switching matrix, the impact of ultrafast optics in high-speed electronics, the physics of low energy optical switching, and all-optical logical elements for optical processing.

Carrier-envelope phase-controlled quantum interference in optical poling.

PubMed

Adachi, Shunsuke; Kobayashi, Takayoshi

2005-04-22

We demonstrate the efficiency of the optical poling process that depends on the CE phase-controlled quantum interference. For the experiment we employed our noncollinear optical parametric amplifier system for the self-stabilization of the CE phase, with the f-to-2f spectral interferometry system to control the CE phase.

Terahertz Optical Gain Based on Intersubband Transitions in Optically-Pumped Semiconductor Quantum Wells: Coherent Pumped-Probe Interactions

NASA Technical Reports Server (NTRS)

Liu, Ansheng; Ning, Cun-Zheng

1999-01-01

Terahertz optical gain due to intersubband transitions in optically-pumped semiconductor quantum wells (QW's) is calculated nonperturbatively. We solve the pump- field-induced nonequilibrium distribution function for each subband of the QW system from a set of rate equations that include both intrasubband and intersubband relaxation processes. The gain arising from population inversion and stimulated Raman processes is calculated in a unified manner. We show that the coherent pump and signal wave interactions contribute significantly to the THz gain. Because of the optical Stark effect and pump-induced population redistribution, optical gain saturation at larger pump intensities is predicted.

EDITORIAL: The 15th Central European Workshop on Quantum Optics The 15th Central European Workshop on Quantum Optics

NASA Astrophysics Data System (ADS)

Bozic, Mirjana; Man'ko, Margarita; Arsenovic, Dusan

2009-07-01

The development of quantum optics was part and parcel of the formation of modern physics following the fundamental work of Max Planck and Albert Einstein, which gave rise to quantum mechanics. The possibility of working with pure quantum objects, like single atoms and single photons, has turned quantum optics into the main tool for testing the fundamentals of quantum physics. Thus, despite a long history, quantum optics nowadays remains an extremely important branch of physics. It represents a natural base for the development of advanced technologies, like quantum information processing and quantum computing. Previous Central European Workshops on Quantum Optics (CEWQO) took place in Palermo (2007), Vienna (2006), Ankara (2005), Trieste (2004), Rostock (2003), Szeged (2002), Prague (2001), Balatonfüred (2000), Olomouc (1999), Prague (1997), Budmerice (1995, 1996), Budapest (1994) and Bratislava (1993). Those meetings offered excellent opportunities for the exchange of knowledge and ideas between leading scientists and young researchers in quantum optics, foundations of quantum mechanics, cavity quantum electrodynamics, photonics, atom optics, condensed matter optics, and quantum informatics, etc. The collaborative spirit and tradition of CEWQO were a great inspiration and help to the Institute of Physics, Belgrade, and the Serbian Academy of Sciences and Arts, as the organizers of CEWQO 2008. The 16th CEWQO will take place in 2009 in Turku, Finland, and the 17th CEWQO will be organized in 2010 in St Andrews, United Kingdom. The 15th CEWQO was organized under the auspices and support of the Ministry of Science of the Republic of Serbia, the Serbian Physical Society, the European Physical Society with sponsorship from the University of Belgrade, the Central European Initiative, the FP6 Program of the European Commission under INCO project QUPOM No 026322, the FP7 Program of the European Commission under project NANOCHARM, Europhysics Letters (EPL), The European Physical Journal (EPJ), and John Wiley and Sons.

Scalable ion-photon quantum interface based on integrated diffractive mirrors

NASA Astrophysics Data System (ADS)

Ghadimi, Moji; Blūms, Valdis; Norton, Benjamin G.; Fisher, Paul M.; Connell, Steven C.; Amini, Jason M.; Volin, Curtis; Hayden, Harley; Pai, Chien-Shing; Kielpinski, David; Lobino, Mirko; Streed, Erik W.

2017-12-01

Quantum networking links quantum processors through remote entanglement for distributed quantum information processing and secure long-range communication. Trapped ions are a leading quantum information processing platform, having demonstrated universal small-scale processors and roadmaps for large-scale implementation. Overall rates of ion-photon entanglement generation, essential for remote trapped ion entanglement, are limited by coupling efficiency into single mode fibers and scaling to many ions. Here, we show a microfabricated trap with integrated diffractive mirrors that couples 4.1(6)% of the fluorescence from a 174Yb+ ion into a single mode fiber, nearly triple the demonstrated bulk optics efficiency. The integrated optic collects 5.8(8)% of the π transition fluorescence, images the ion with sub-wavelength resolution, and couples 71(5)% of the collected light into the fiber. Our technology is suitable for entangling multiple ions in parallel and overcomes mode quality limitations of existing integrated optical interconnects.

Unconditional room-temperature quantum memory

NASA Astrophysics Data System (ADS)

Hosseini, M.; Campbell, G.; Sparkes, B. M.; Lam, P. K.; Buchler, B. C.

2011-10-01

Just as classical information systems require buffers and memory, the same is true for quantum information systems. The potential that optical quantum information processing holds for revolutionizing computation and communication is therefore driving significant research into developing optical quantum memory. A practical optical quantum memory must be able to store and recall quantum states on demand with high efficiency and low noise. Ideally, the platform for the memory would also be simple and inexpensive. Here, we present a complete tomographic reconstruction of quantum states that have been stored in the ground states of rubidium in a vapour cell operating at around 80°C. Without conditional measurements, we show recall fidelity up to 98% for coherent pulses containing around one photon. To unambiguously verify that our memory beats the quantum no-cloning limit we employ state-independent verification using conditional variance and signal-transfer coefficients.

Quantum optical circulator controlled by a single chirally coupled atom

NASA Astrophysics Data System (ADS)

Scheucher, Michael; Hilico, Adèle; Will, Elisa; Volz, Jürgen; Rauschenbeutel, Arno

2016-12-01

Integrated nonreciprocal optical components, which have an inherent asymmetry between their forward and backward propagation direction, are key for routing signals in photonic circuits. Here, we demonstrate a fiber-integrated quantum optical circulator operated by a single atom. Its nonreciprocal behavior arises from the chiral interaction between the atom and the transversally confined light. We demonstrate that the internal quantum state of the atom controls the operation direction of the circulator and that it features a strongly nonlinear response at the single-photon level. This enables, for example, photon number-dependent routing and novel quantum simulation protocols. Furthermore, such a circulator can in principle be prepared in a coherent superposition of its operational states and may become a key element for quantum information processing in scalable integrated optical circuits.

Efficient quantum computing using coherent photon conversion.

PubMed

Langford, N K; Ramelow, S; Prevedel, R; Munro, W J; Milburn, G J; Zeilinger, A

2011-10-12

Single photons are excellent quantum information carriers: they were used in the earliest demonstrations of entanglement and in the production of the highest-quality entanglement reported so far. However, current schemes for preparing, processing and measuring them are inefficient. For example, down-conversion provides heralded, but randomly timed, single photons, and linear optics gates are inherently probabilistic. Here we introduce a deterministic process--coherent photon conversion (CPC)--that provides a new way to generate and process complex, multiquanta states for photonic quantum information applications. The technique uses classically pumped nonlinearities to induce coherent oscillations between orthogonal states of multiple quantum excitations. One example of CPC, based on a pumped four-wave-mixing interaction, is shown to yield a single, versatile process that provides a full set of photonic quantum processing tools. This set satisfies the DiVincenzo criteria for a scalable quantum computing architecture, including deterministic multiqubit entanglement gates (based on a novel form of photon-photon interaction), high-quality heralded single- and multiphoton states free from higher-order imperfections, and robust, high-efficiency detection. It can also be used to produce heralded multiphoton entanglement, create optically switchable quantum circuits and implement an improved form of down-conversion with reduced higher-order effects. Such tools are valuable building blocks for many quantum-enabled technologies. Finally, using photonic crystal fibres we experimentally demonstrate quantum correlations arising from a four-colour nonlinear process suitable for CPC and use these measurements to study the feasibility of reaching the deterministic regime with current technology. Our scheme, which is based on interacting bosonic fields, is not restricted to optical systems but could also be implemented in optomechanical, electromechanical and superconducting systems with extremely strong intrinsic nonlinearities. Furthermore, exploiting higher-order nonlinearities with multiple pump fields yields a mechanism for multiparty mediation of the complex, coherent dynamics.

Implementation and characterization of active feed-forward for deterministic linear optics quantum computing

NASA Astrophysics Data System (ADS)

Böhi, P.; Prevedel, R.; Jennewein, T.; Stefanov, A.; Tiefenbacher, F.; Zeilinger, A.

2007-12-01

In general, quantum computer architectures which are based on the dynamical evolution of quantum states, also require the processing of classical information, obtained by measurements of the actual qubits that make up the computer. This classical processing involves fast, active adaptation of subsequent measurements and real-time error correction (feed-forward), so that quantum gates and algorithms can be executed in a deterministic and hence error-free fashion. This is also true in the linear optical regime, where the quantum information is stored in the polarization state of photons. The adaptation of the photon’s polarization can be achieved in a very fast manner by employing electro-optical modulators, which change the polarization of a trespassing photon upon appliance of a high voltage. In this paper we discuss techniques for implementing fast, active feed-forward at the single photon level and we present their application in the context of photonic quantum computing. This includes the working principles and the characterization of the EOMs as well as a description of the switching logics, both of which allow quantum computation at an unprecedented speed.

Coherent Spin Control at the Quantum Level in an Ensemble-Based Optical Memory.

PubMed

Jobez, Pierre; Laplane, Cyril; Timoney, Nuala; Gisin, Nicolas; Ferrier, Alban; Goldner, Philippe; Afzelius, Mikael

2015-06-12

Long-lived quantum memories are essential components of a long-standing goal of remote distribution of entanglement in quantum networks. These can be realized by storing the quantum states of light as single-spin excitations in atomic ensembles. However, spin states are often subjected to different dephasing processes that limit the storage time, which in principle could be overcome using spin-echo techniques. Theoretical studies suggest this to be challenging due to unavoidable spontaneous emission noise in ensemble-based quantum memories. Here, we demonstrate spin-echo manipulation of a mean spin excitation of 1 in a large solid-state ensemble, generated through storage of a weak optical pulse. After a storage time of about 1 ms we optically read-out the spin excitation with a high signal-to-noise ratio. Our results pave the way for long-duration optical quantum storage using spin-echo techniques for any ensemble-based memory.

High-Efficiency and High-Power Mid-Wave Infrared Cascade Lasers

DTIC Science & Technology

2012-10-01

internal quantum efficiency () and factor (2) is usually called the optical extraction efficiency (). The optical extraction efficiency ... quantum efficiency involves more fundamental parameters corresponding to the microscopic processes of the device operation, nevertheless, it can be...deriving parameters such as the internal quantum efficiency of a QC laser, the entire injector miniband can be treated as a single virtual state

Effects of rapid thermal annealing on the optical properties of strain-free quantum ring solar cells

PubMed Central

2013-01-01

Strain-free GaAs/Al0.33Ga0.67As quantum rings are fabricated by droplet epitaxy. Both photoresponse and photoluminescence spectra confirm optical transitions in quantum rings, suggesting that droplet epitaxial nanomaterials are applicable to intermediate band solar cells. The effects of post-growth annealing on the quantum ring solar cells are investigated, and the optical properties of the solar cells with and without thermal treatment are characterized by photoluminescence technique. Rapid thermal annealing treatment has resulted in the significant improvement of material quality, which can be served as a standard process for quantum structure solar cells grown by droplet epitaxy. PMID:23281811

Nonadiabatic quantum path analysis of high-order harmonic generation: Role of the carrier-envelope phase on short and long paths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sansone, G.; Stagira, S.; Nisoli, M.

2004-07-01

High-order harmonic generation process in the few- and multiple-optical-cycle regime is theoretically investigated, using the saddle-point method generalized to account for nonadiabatic effects. The influence of the carrier-envelope phase of the driving pulses on the various electron quantum paths is analyzed. We demonstrate that the short and long quantum paths are influenced in different ways by the carrier-envelope phase. In particular, we show that clear phase effects are visible on the long quantum paths even in the multiple-optical-cycle regime, while the short quantum paths are significantly influenced by the carrier-envelope phase only in the few-optical-cycle regime.

Multimode entanglement in reconfigurable graph states using optical frequency combs

PubMed Central

Cai, Y.; Roslund, J.; Ferrini, G.; Arzani, F.; Xu, X.; Fabre, C.; Treps, N.

2017-01-01

Multimode entanglement is an essential resource for quantum information processing and quantum metrology. However, multimode entangled states are generally constructed by targeting a specific graph configuration. This yields to a fixed experimental setup that therefore exhibits reduced versatility and scalability. Here we demonstrate an optical on-demand, reconfigurable multimode entangled state, using an intrinsically multimode quantum resource and a homodyne detection apparatus. Without altering either the initial squeezing source or experimental architecture, we realize the construction of thirteen cluster states of various sizes and connectivities as well as the implementation of a secret sharing protocol. In particular, this system enables the interrogation of quantum correlations and fluctuations for any multimode Gaussian state. This initiates an avenue for implementing on-demand quantum information processing by only adapting the measurement process and not the experimental layout. PMID:28585530

III–V quantum light source and cavity-QED on Silicon

PubMed Central

Luxmoore, I. J.; Toro, R.; Pozo-Zamudio, O. Del; Wasley, N. A.; Chekhovich, E. A.; Sanchez, A. M.; Beanland, R.; Fox, A. M.; Skolnick, M. S.; Liu, H. Y.; Tartakovskii, A. I.

2013-01-01

Non-classical light sources offer a myriad of possibilities in both fundamental science and commercial applications. Single photons are the most robust carriers of quantum information and can be exploited for linear optics quantum information processing. Scale-up requires miniaturisation of the waveguide circuit and multiple single photon sources. Silicon photonics, driven by the incentive of optical interconnects is a highly promising platform for the passive optical components, but integrated light sources are limited by silicon's indirect band-gap. III–V semiconductor quantum-dots, on the other hand, are proven quantum emitters. Here we demonstrate single-photon emission from quantum-dots coupled to photonic crystal nanocavities fabricated from III–V material grown directly on silicon substrates. The high quality of the III–V material and photonic structures is emphasized by observation of the strong-coupling regime. This work opens-up the advantages of silicon photonics to the integration and scale-up of solid-state quantum optical systems. PMID:23393621

A photon-photon quantum gate based on a single atom in an optical resonator.

PubMed

Hacker, Bastian; Welte, Stephan; Rempe, Gerhard; Ritter, Stephan

2016-08-11

That two photons pass each other undisturbed in free space is ideal for the faithful transmission of information, but prohibits an interaction between the photons. Such an interaction is, however, required for a plethora of applications in optical quantum information processing. The long-standing challenge here is to realize a deterministic photon-photon gate, that is, a mutually controlled logic operation on the quantum states of the photons. This requires an interaction so strong that each of the two photons can shift the other's phase by π radians. For polarization qubits, this amounts to the conditional flipping of one photon's polarization to an orthogonal state. So far, only probabilistic gates based on linear optics and photon detectors have been realized, because "no known or foreseen material has an optical nonlinearity strong enough to implement this conditional phase shift''. Meanwhile, tremendous progress in the development of quantum-nonlinear systems has opened up new possibilities for single-photon experiments. Platforms range from Rydberg blockade in atomic ensembles to single-atom cavity quantum electrodynamics. Applications such as single-photon switches and transistors, two-photon gateways, nondestructive photon detectors, photon routers and nonlinear phase shifters have been demonstrated, but none of them with the ideal information carriers: optical qubits in discriminable modes. Here we use the strong light-matter coupling provided by a single atom in a high-finesse optical resonator to realize the Duan-Kimble protocol of a universal controlled phase flip (π phase shift) photon-photon quantum gate. We achieve an average gate fidelity of (76.2 ± 3.6) per cent and specifically demonstrate the capability of conditional polarization flipping as well as entanglement generation between independent input photons. This photon-photon quantum gate is a universal quantum logic element, and therefore could perform most existing two-photon operations. The demonstrated feasibility of deterministic protocols for the optical processing of quantum information could lead to new applications in which photons are essential, especially long-distance quantum communication and scalable quantum computing.

Nanophotonic rare-earth quantum memory with optically controlled retrieval.

PubMed

Zhong, Tian; Kindem, Jonathan M; Bartholomew, John G; Rochman, Jake; Craiciu, Ioana; Miyazono, Evan; Bettinelli, Marco; Cavalli, Enrico; Verma, Varun; Nam, Sae Woo; Marsili, Francesco; Shaw, Matthew D; Beyer, Andrew D; Faraon, Andrei

2017-09-29

Optical quantum memories are essential elements in quantum networks for long-distance distribution of quantum entanglement. Scalable development of quantum network nodes requires on-chip qubit storage functionality with control of the readout time. We demonstrate a high-fidelity nanophotonic quantum memory based on a mesoscopic neodymium ensemble coupled to a photonic crystal cavity. The nanocavity enables >95% spin polarization for efficient initialization of the atomic frequency comb memory and time bin-selective readout through an enhanced optical Stark shift of the comb frequencies. Our solid-state memory is integrable with other chip-scale photon source and detector devices for multiplexed quantum and classical information processing at the network nodes. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Large conditional single-photon cross-phase modulation

NASA Astrophysics Data System (ADS)

Beck, Kristin; Hosseini, Mahdi; Duan, Yiheng; Vuletic, Vladan

2016-05-01

Deterministic optical quantum logic requires a nonlinear quantum process that alters the phase of a quantum optical state by π through interaction with only one photon. Here, we demonstrate a large conditional cross-phase modulation between a signal field, stored inside an atomic quantum memory, and a control photon that traverses a high-finesse optical cavity containing the atomic memory. This approach avoids fundamental limitations associated with multimode effects for traveling optical photons. We measure a conditional cross-phase shift of up to π / 3 between the retrieved signal and control photons, and confirm deterministic entanglement between the signal and control modes by extracting a positive concurrence. With a moderate improvement in cavity finesse, our system can reach a coherent phase shift of p at low loss, enabling deterministic and universal photonic quantum logic. Preprint: arXiv:1512.02166 [quant-ph

Quantum nonlinear optics without photons

NASA Astrophysics Data System (ADS)

Stassi, Roberto; Macrı, Vincenzo; Kockum, Anton Frisk; Di Stefano, Omar; Miranowicz, Adam; Savasta, Salvatore; Nori, Franco

2017-08-01

Spontaneous parametric down-conversion is a well-known process in quantum nonlinear optics in which a photon incident on a nonlinear crystal spontaneously splits into two photons. Here we propose an analogous physical process where one excited atom directly transfers its excitation to a pair of spatially separated atoms with probability approaching 1. The interaction is mediated by the exchange of virtual rather than real photons. This nonlinear atomic process is coherent and reversible, so the pair of excited atoms can transfer the excitation back to the first one: the atomic analog of sum-frequency generation of light. The parameters used to investigate this process correspond to experimentally demonstrated values in ultrastrong circuit quantum electrodynamics. This approach can be extended to realize other nonlinear interatomic processes, such as four-atom mixing, and is an attractive architecture for the realization of quantum devices on a chip. We show that four-qubit mixing can efficiently implement quantum repetition codes and, thus, can be used for error-correction codes.

Teleportation of a Toffoli gate among distant solid-state qubits with quantum dots embedded in optical microcavities

PubMed Central

Hu, Shi; Cui, Wen-Xue; Wang, Dong-Yang; Bai, Cheng-Hua; Guo, Qi; Wang, Hong-Fu; Zhu, Ai-Dong; Zhang, Shou

2015-01-01

Teleportation of unitary operations can be viewed as a quantum remote control. The remote realization of robust multiqubit logic gates among distant long-lived qubit registers is a key challenge for quantum computation and quantum information processing. Here we propose a simple and deterministic scheme for teleportation of a Toffoli gate among three spatially separated electron spin qubits in optical microcavities by using local linear optical operations, an auxiliary electron spin, two circularly-polarized entangled photon pairs, photon measurements, and classical communication. We assess the feasibility of the scheme and show that the scheme can be achieved with high average fidelity under the current technology. The scheme opens promising perspectives for constructing long-distance quantum communication and quantum computation networks with solid-state qubits. PMID:26225781

Teleportation of a Toffoli gate among distant solid-state qubits with quantum dots embedded in optical microcavities.

PubMed

Hu, Shi; Cui, Wen-Xue; Wang, Dong-Yang; Bai, Cheng-Hua; Guo, Qi; Wang, Hong-Fu; Zhu, Ai-Dong; Zhang, Shou

2015-07-30

Teleportation of unitary operations can be viewed as a quantum remote control. The remote realization of robust multiqubit logic gates among distant long-lived qubit registers is a key challenge for quantum computation and quantum information processing. Here we propose a simple and deterministic scheme for teleportation of a Toffoli gate among three spatially separated electron spin qubits in optical microcavities by using local linear optical operations, an auxiliary electron spin, two circularly-polarized entangled photon pairs, photon measurements, and classical communication. We assess the feasibility of the scheme and show that the scheme can be achieved with high average fidelity under the current technology. The scheme opens promising perspectives for constructing long-distance quantum communication and quantum computation networks with solid-state qubits.

Biological measurement beyond the quantum limit

NASA Astrophysics Data System (ADS)

Taylor, Michael; Janousek, Jiri; Daria, Vincent; Knittel, Joachim; Hage, Boris; Bachor, Hans; Bowen, Warwick

2013-05-01

Biology is an important frontier for quantum metrology, with quantum enhanced sensitivity allowing optical intensities to be lowered, and a consequent reduction in specimen damage and photochemical intrusion upon biological processes. Here we demonstrate the first biological measurement with precision surpassing the quantum noise limit. Naturally occurring lipid granules within living yeast cells were tracked in real time with sensitivity surpassing the quantum noise limit by 42% as they diffuse through the cytoplasm and interact with embedded polymer networks. This allowed dynamic mechanical properties of the cytoplasm to be determined with a 64% higher measurement rate than possible classically. To enable this, a new microscopy system was developed which is compatible with squeezed light, and which utilized a novel optical lock-in technique to allow quantum enhancement down to 10 Hz. This method is widely applicable, extending the reach of quantum enhanced measurement to many dynamic biological processes.

Reconfigurable optical implementation of quantum complex networks

NASA Astrophysics Data System (ADS)

Nokkala, J.; Arzani, F.; Galve, F.; Zambrini, R.; Maniscalco, S.; Piilo, J.; Treps, N.; Parigi, V.

2018-05-01

Network theory has played a dominant role in understanding the structure of complex systems and their dynamics. Recently, quantum complex networks, i.e. collections of quantum systems arranged in a non-regular topology, have been theoretically explored leading to significant progress in a multitude of diverse contexts including, e.g., quantum transport, open quantum systems, quantum communication, extreme violation of local realism, and quantum gravity theories. Despite important progress in several quantum platforms, the implementation of complex networks with arbitrary topology in quantum experiments is still a demanding task, especially if we require both a significant size of the network and the capability of generating arbitrary topology—from regular to any kind of non-trivial structure—in a single setup. Here we propose an all optical and reconfigurable implementation of quantum complex networks. The experimental proposal is based on optical frequency combs, parametric processes, pulse shaping and multimode measurements allowing the arbitrary control of the number of the nodes (optical modes) and topology of the links (interactions between the modes) within the network. Moreover, we also show how to simulate quantum dynamics within the network combined with the ability to address its individual nodes. To demonstrate the versatility of these features, we discuss the implementation of two recently proposed probing techniques for quantum complex networks and structured environments.

On-chip continuous-variable quantum entanglement

NASA Astrophysics Data System (ADS)

Masada, Genta; Furusawa, Akira

2016-09-01

Entanglement is an essential feature of quantum theory and the core of the majority of quantum information science and technologies. Quantum computing is one of the most important fruits of quantum entanglement and requires not only a bipartite entangled state but also more complicated multipartite entanglement. In previous experimental works to demonstrate various entanglement-based quantum information processing, light has been extensively used. Experiments utilizing such a complicated state need highly complex optical circuits to propagate optical beams and a high level of spatial interference between different light beams to generate quantum entanglement or to efficiently perform balanced homodyne measurement. Current experiments have been performed in conventional free-space optics with large numbers of optical components and a relatively large-sized optical setup. Therefore, they are limited in stability and scalability. Integrated photonics offer new tools and additional capabilities for manipulating light in quantum information technology. Owing to integrated waveguide circuits, it is possible to stabilize and miniaturize complex optical circuits and achieve high interference of light beams. The integrated circuits have been firstly developed for discrete-variable systems and then applied to continuous-variable systems. In this article, we review the currently developed scheme for generation and verification of continuous-variable quantum entanglement such as Einstein-Podolsky-Rosen beams using a photonic chip where waveguide circuits are integrated. This includes balanced homodyne measurement of a squeezed state of light. As a simple example, we also review an experiment for generating discrete-variable quantum entanglement using integrated waveguide circuits.

Room temperature single photon source using fiber-integrated hexagonal boron nitride

NASA Astrophysics Data System (ADS)

Vogl, Tobias; Lu, Yuerui; Lam, Ping Koy

2017-07-01

Single photons are a key resource for quantum optics and optical quantum information processing. The integration of scalable room temperature quantum emitters into photonic circuits remains to be a technical challenge. Here we utilize a defect center in hexagonal boron nitride (hBN) attached by Van der Waals force onto a multimode fiber as a single photon source. We perform an optical characterization of the source in terms of spectrum, state lifetime, power saturation and photostability. A special feature of our source is that it allows for easy switching between fiber-coupled and free space single photon generation modes. In order to prove the quantum nature of the emission we measure the second-order correlation function {{g}(2)}≤ft(τ \\right) . For both fiber-coupled and free space emission, the {{g}(2)}≤ft(τ \\right) dips below 0.5 indicating operation in the single photon regime. The results so far demonstrate the feasibility of 2D material single photon sources for scalable photonic quantum information processing.

Direct optical state preparation of the dark exciton in a quantum dot

NASA Astrophysics Data System (ADS)

Lüker, S.; Kuhn, T.; Reiter, D. E.

2015-11-01

Because of their weak coupling to the electromagnetic field, dark excitons in semiconductor quantum dots possess extremely long lifetimes, which makes them attractive candidates for quantum information processing. On the other hand, the preparation and manipulation of dark states is challenging, because commonly used optical excitation mechanisms are not applicable. We propose an efficient mechanism for the deterministic preparation of the dark exciton exploiting the application of a tilted magnetic field and the optical excitation with a chirped, i.e., frequency modulated, laser pulse.

A single-atom quantum memory.

PubMed

Specht, Holger P; Nölleke, Christian; Reiserer, Andreas; Uphoff, Manuel; Figueroa, Eden; Ritter, Stephan; Rempe, Gerhard

2011-05-12

The faithful storage of a quantum bit (qubit) of light is essential for long-distance quantum communication, quantum networking and distributed quantum computing. The required optical quantum memory must be able to receive and recreate the photonic qubit; additionally, it must store an unknown quantum state of light better than any classical device. So far, these two requirements have been met only by ensembles of material particles that store the information in collective excitations. Recent developments, however, have paved the way for an approach in which the information exchange occurs between single quanta of light and matter. This single-particle approach allows the material qubit to be addressed, which has fundamental advantages for realistic implementations. First, it enables a heralding mechanism that signals the successful storage of a photon by means of state detection; this can be used to combat inevitable losses and finite efficiencies. Second, it allows for individual qubit manipulations, opening up avenues for in situ processing of the stored quantum information. Here we demonstrate the most fundamental implementation of such a quantum memory, by mapping arbitrary polarization states of light into and out of a single atom trapped inside an optical cavity. The memory performance is tested with weak coherent pulses and analysed using full quantum process tomography. The average fidelity is measured to be 93%, and low decoherence rates result in qubit coherence times exceeding 180  microseconds. This makes our system a versatile quantum node with excellent prospects for applications in optical quantum gates and quantum repeaters.

Synchronization of optical photons for quantum information processing.

PubMed

Makino, Kenzo; Hashimoto, Yosuke; Yoshikawa, Jun-Ichi; Ohdan, Hideaki; Toyama, Takeshi; van Loock, Peter; Furusawa, Akira

2016-05-01

A fundamental element of quantum information processing with photonic qubits is the nonclassical quantum interference between two photons when they bunch together via the Hong-Ou-Mandel (HOM) effect. Ultimately, many such photons must be processed in complex interferometric networks. For this purpose, it is essential to synchronize the arrival times of the flying photons and to keep their purities high. On the basis of the recent experimental success of single-photon storage with high purity, we demonstrate for the first time the HOM interference of two heralded, nearly pure optical photons synchronized through two independent quantum memories. Controlled storage times of up to 1.8 μs for about 90 events per second were achieved with purities that were sufficiently high for a negative Wigner function confirmed with homodyne measurements.

Synchronization of optical photons for quantum information processing

PubMed Central

Makino, Kenzo; Hashimoto, Yosuke; Yoshikawa, Jun-ichi; Ohdan, Hideaki; Toyama, Takeshi; van Loock, Peter; Furusawa, Akira

2016-01-01

A fundamental element of quantum information processing with photonic qubits is the nonclassical quantum interference between two photons when they bunch together via the Hong-Ou-Mandel (HOM) effect. Ultimately, many such photons must be processed in complex interferometric networks. For this purpose, it is essential to synchronize the arrival times of the flying photons and to keep their purities high. On the basis of the recent experimental success of single-photon storage with high purity, we demonstrate for the first time the HOM interference of two heralded, nearly pure optical photons synchronized through two independent quantum memories. Controlled storage times of up to 1.8 μs for about 90 events per second were achieved with purities that were sufficiently high for a negative Wigner function confirmed with homodyne measurements. PMID:27386536

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendrickson, Scott M.; Foster, Amy C.; Camacho, Ryan M.

In this paper, we provide a review of recent progress in integrated nonlinear photonics with a focus on emerging applications in all-optical signal processing, ultra-low-power all-optical switching, and quantum information processing.

Controlled exciton transfer between quantum dots with acoustic phonons taken into account

DOE Office of Scientific and Technical Information (OSTI.GOV)

Golovinski, P. A., E-mail: golovinski@bk.ru

2015-09-15

A system of excitons in two quantum dots coupled by the dipole–dipole interaction is investigated. The excitation transfer process controlled by the optical Stark effect at nonresonant frequencies is considered and the effect of the interaction between excitons and acoustic phonons in a medium on this process is taken into account. The system evolution is described using quantum Heisenberg equations. A truncated set of equations is obtained and the transfer dynamics is numerically simulated. High-efficiency picosecond switching of the excitation transfer by a laser pulse with a rectangular envelope is demonstrated. The dependence of picosecond switching on the quantum-dot parametersmore » and optical-pulse length is presented.« less

Underlying Information Technology Tailored Quantum Error Correction

DTIC Science & Technology

2006-07-28

typically constructed by using an optical beam splitter . • We used a decoherence-free-subspace encoding to reduce the sensitivity of an optical Deutsch...simplification of design constraints in solid state QC (incl. quantum dots and superconducting qubits), hybrid quantum error correction and prevention methods...process tomography on one- and two-photon polarisation states, from full and partial data "• Accomplished complete two-photon QPT. "• Discovered surprising

Towards a Quantum Interface between Diamond Spin Qubits and Phonons in an Optical Trap

NASA Astrophysics Data System (ADS)

Ji, Peng; Momeen, M. Ummal; Hsu, Jen-Feng; D'Urso, Brian; Dutt, Gurudev

2014-05-01

We introduce a method to optically levitate a pre-selected nanodiamond crystal in air or vacuum. The nanodiamond containing nitrogen-vacancy (NV) centers is suspended on a monolayer of graphene transferred onto a patterned substrate. Laser light is focused onto the sample, using a home-built confocal microscope with a high numerical aperture (NA = 0.9) objective, simultaneously burning the graphene and creating a 3D optical trap that captures the falling nano-diamond at the beam waist. The trapped diamond is an ultra-high-Q mechanical oscillator, allowing us to engineer strong linear and quadratic coupling between the spin of the NV center and the phonon mode. The system could result in an ideal quantum interface between a spin qubit and vibrational phonon mode, potentially enabling applications in quantum information processing and sensing the development of quantum information storage and processing.

Large conditional single-photon cross-phase modulation

PubMed Central

Hosseini, Mahdi; Duan, Yiheng; Vuletić, Vladan

2016-01-01

Deterministic optical quantum logic requires a nonlinear quantum process that alters the phase of a quantum optical state by π through interaction with only one photon. Here, we demonstrate a large conditional cross-phase modulation between a signal field, stored inside an atomic quantum memory, and a control photon that traverses a high-finesse optical cavity containing the atomic memory. This approach avoids fundamental limitations associated with multimode effects for traveling optical photons. We measure a conditional cross-phase shift of π/6 (and up to π/3 by postselection on photons that remain in the system longer than average) between the retrieved signal and control photons, and confirm deterministic entanglement between the signal and control modes by extracting a positive concurrence. By upgrading to a state-of-the-art cavity, our system can reach a coherent phase shift of π at low loss, enabling deterministic and universal photonic quantum logic. PMID:27519798

Heralded high-efficiency quantum repeater with atomic ensembles assisted by faithful single-photon transmission

NASA Astrophysics Data System (ADS)

Li, Tao; Deng, Fu-Guo

2015-10-01

Quantum repeater is one of the important building blocks for long distance quantum communication network. The previous quantum repeaters based on atomic ensembles and linear optical elements can only be performed with a maximal success probability of 1/2 during the entanglement creation and entanglement swapping procedures. Meanwhile, the polarization noise during the entanglement distribution process is harmful to the entangled channel created. Here we introduce a general interface between a polarized photon and an atomic ensemble trapped in a single-sided optical cavity, and with which we propose a high-efficiency quantum repeater protocol in which the robust entanglement distribution is accomplished by the stable spatial-temporal entanglement and it can in principle create the deterministic entanglement between neighboring atomic ensembles in a heralded way as a result of cavity quantum electrodynamics. Meanwhile, the simplified parity-check gate makes the entanglement swapping be completed with unity efficiency, other than 1/2 with linear optics. We detail the performance of our protocol with current experimental parameters and show its robustness to the imperfections, i.e., detuning and coupling variation, involved in the reflection process. These good features make it a useful building block in long distance quantum communication.

Heralded high-efficiency quantum repeater with atomic ensembles assisted by faithful single-photon transmission.

PubMed

Li, Tao; Deng, Fu-Guo

2015-10-27

Quantum repeater is one of the important building blocks for long distance quantum communication network. The previous quantum repeaters based on atomic ensembles and linear optical elements can only be performed with a maximal success probability of 1/2 during the entanglement creation and entanglement swapping procedures. Meanwhile, the polarization noise during the entanglement distribution process is harmful to the entangled channel created. Here we introduce a general interface between a polarized photon and an atomic ensemble trapped in a single-sided optical cavity, and with which we propose a high-efficiency quantum repeater protocol in which the robust entanglement distribution is accomplished by the stable spatial-temporal entanglement and it can in principle create the deterministic entanglement between neighboring atomic ensembles in a heralded way as a result of cavity quantum electrodynamics. Meanwhile, the simplified parity-check gate makes the entanglement swapping be completed with unity efficiency, other than 1/2 with linear optics. We detail the performance of our protocol with current experimental parameters and show its robustness to the imperfections, i.e., detuning and coupling variation, involved in the reflection process. These good features make it a useful building block in long distance quantum communication.

Heralded high-efficiency quantum repeater with atomic ensembles assisted by faithful single-photon transmission

PubMed Central

Li, Tao; Deng, Fu-Guo

2015-01-01

Quantum repeater is one of the important building blocks for long distance quantum communication network. The previous quantum repeaters based on atomic ensembles and linear optical elements can only be performed with a maximal success probability of 1/2 during the entanglement creation and entanglement swapping procedures. Meanwhile, the polarization noise during the entanglement distribution process is harmful to the entangled channel created. Here we introduce a general interface between a polarized photon and an atomic ensemble trapped in a single-sided optical cavity, and with which we propose a high-efficiency quantum repeater protocol in which the robust entanglement distribution is accomplished by the stable spatial-temporal entanglement and it can in principle create the deterministic entanglement between neighboring atomic ensembles in a heralded way as a result of cavity quantum electrodynamics. Meanwhile, the simplified parity-check gate makes the entanglement swapping be completed with unity efficiency, other than 1/2 with linear optics. We detail the performance of our protocol with current experimental parameters and show its robustness to the imperfections, i.e., detuning and coupling variation, involved in the reflection process. These good features make it a useful building block in long distance quantum communication. PMID:26502993

Telecom-Wavelength Atomic Quantum Memory in Optical Fiber for Heralded Polarization Qubits.

PubMed

Jin, Jeongwan; Saglamyurek, Erhan; Puigibert, Marcel lí Grimau; Verma, Varun; Marsili, Francesco; Nam, Sae Woo; Oblak, Daniel; Tittel, Wolfgang

2015-10-02

Polarization-encoded photons at telecommunication wavelengths provide a compelling platform for practical realizations of photonic quantum information technologies due to the ease of performing single qubit manipulations, the availability of polarization-entangled photon-pair sources, and the possibility of leveraging existing fiber-optic links for distributing qubits over long distances. An optical quantum memory compatible with this platform could serve as a building block for these technologies. Here we present the first experimental demonstration of an atomic quantum memory that directly allows for reversible mapping of quantum states encoded in the polarization degree of freedom of a telecom-wavelength photon. We show that heralded polarization qubits at a telecom wavelength are stored and retrieved with near-unity fidelity by implementing the atomic frequency comb protocol in an ensemble of erbium atoms doped into an optical fiber. Despite remaining limitations in our proof-of-principle demonstration such as small storage efficiency and storage time, our broadband light-matter interface reveals the potential for use in future quantum information processing.

MURI Center for Photonic Quantum Information Systems

DTIC Science & Technology

2009-10-16

conversion; solid- state quantum gates based on quantum dots in semiconductors and on NV centers in diamond; quantum memories using optical storage...of our high-speed quantum cryptography systems, and also by continuing to work on quantum information encoding into transverse spatial modes. 14...make use of cavity QED effects for quantum information processing, the quantum dot needs to be addressed coherently . We have probed the QD-cavity

Demonstration of spatial-light-modulation-based four-wave mixing in cold atoms

NASA Astrophysics Data System (ADS)

Juo, Jz-Yuan; Lin, Jia-Kang; Cheng, Chin-Yao; Liu, Zi-Yu; Yu, Ite A.; Chen, Yong-Fan

2018-05-01

Long-distance quantum optical communications usually require efficient wave-mixing processes to convert the wavelengths of single photons. Many quantum applications based on electromagnetically induced transparency (EIT) have been proposed and demonstrated at the single-photon level, such as quantum memories, all-optical transistors, and cross-phase modulations. However, EIT-based four-wave mixing (FWM) in a resonant double-Λ configuration has a maximum conversion efficiency (CE) of 25% because of absorptive loss due to spontaneous emission. An improved scheme using spatially modulated intensities of two control fields has been theoretically proposed to overcome this conversion limit. In this study, we first demonstrate wavelength conversion from 780 to 795 nm with a 43% CE by using this scheme at an optical density (OD) of 19 in cold 87Rb atoms. According to the theoretical model, the CE in the proposed scheme can further increase to 96% at an OD of 240 under ideal conditions, thereby attaining an identical CE to that of the previous nonresonant double-Λ scheme at half the OD. This spatial-light-modulation-based FWM scheme can achieve a near-unity CE, thus providing an easy method of implementing an efficient quantum wavelength converter for all-optical quantum information processing.

A multiplexed light-matter interface for fibre-based quantum networks

PubMed Central

Saglamyurek, Erhan; Grimau Puigibert, Marcelli; Zhou, Qiang; Giner, Lambert; Marsili, Francesco; Verma, Varun B.; Woo Nam, Sae; Oesterling, Lee; Nippa, David; Oblak, Daniel; Tittel, Wolfgang

2016-01-01

Processing and distributing quantum information using photons through fibre-optic or free-space links are essential for building future quantum networks. The scalability needed for such networks can be achieved by employing photonic quantum states that are multiplexed into time and/or frequency, and light-matter interfaces that are able to store and process such states with large time-bandwidth product and multimode capacities. Despite important progress in developing such devices, the demonstration of these capabilities using non-classical light remains challenging. Here, employing the atomic frequency comb quantum memory protocol in a cryogenically cooled erbium-doped optical fibre, we report the quantum storage of heralded single photons at a telecom-wavelength (1.53 μm) with a time-bandwidth product approaching 800. Furthermore, we demonstrate frequency-multimode storage and memory-based spectral-temporal photon manipulation. Notably, our demonstrations rely on fully integrated quantum technologies operating at telecommunication wavelengths. With improved storage efficiency, our light-matter interface may become a useful tool in future quantum networks. PMID:27046076

A multiplexed light-matter interface for fibre-based quantum networks.

PubMed

Saglamyurek, Erhan; Grimau Puigibert, Marcelli; Zhou, Qiang; Giner, Lambert; Marsili, Francesco; Verma, Varun B; Woo Nam, Sae; Oesterling, Lee; Nippa, David; Oblak, Daniel; Tittel, Wolfgang

2016-04-05

Processing and distributing quantum information using photons through fibre-optic or free-space links are essential for building future quantum networks. The scalability needed for such networks can be achieved by employing photonic quantum states that are multiplexed into time and/or frequency, and light-matter interfaces that are able to store and process such states with large time-bandwidth product and multimode capacities. Despite important progress in developing such devices, the demonstration of these capabilities using non-classical light remains challenging. Here, employing the atomic frequency comb quantum memory protocol in a cryogenically cooled erbium-doped optical fibre, we report the quantum storage of heralded single photons at a telecom-wavelength (1.53 μm) with a time-bandwidth product approaching 800. Furthermore, we demonstrate frequency-multimode storage and memory-based spectral-temporal photon manipulation. Notably, our demonstrations rely on fully integrated quantum technologies operating at telecommunication wavelengths. With improved storage efficiency, our light-matter interface may become a useful tool in future quantum networks.

Fano Effect and Quantum Entanglement in Hybrid Semiconductor Quantum Dot-Metal Nanoparticle System.

PubMed

He, Yong; Zhu, Ka-Di

2017-06-20

In this paper, we review the investigation for the light-matter interaction between surface plasmon field in metal nanoparticle (MNP) and the excitons in semiconductor quantum dots (SQDs) in hybrid SQD-MNP system under the full quantum description. The exciton-plasmon interaction gives rise to the modified decay rate and the exciton energy shift which are related to the exciton energy by using a quantum transformation method. We illustrate the responses of the hybrid SQD-MNP system to external field, and reveal Fano effect shown in the absorption spectrum. We demonstrate quantum entanglement between two SQD mediated by surface plasmon field. In the absence of a laser field, concurrence of quantum entanglement will disappear after a few ns. If the laser field is present, the steady states appear, so that quantum entanglement produced will reach a steady-state entanglement. Because one of all optical pathways to induce Fano effect refers to the generation of quantum entangled states, It is shown that the concurrence of quantum entanglement can be obtained by observation for Fano effect. In a hybrid system including two MNP and a SQD, because the two Fano quantum interference processes share a segment of all optical pathways, there is correlation between the Fano effects of the two MNP. The investigations for the light-matter interaction in hybrid SQD-MNP system can pave the way for the development of the optical processing devices and quantum information based on the exciton-plasmon interaction.

Fano Effect and Quantum Entanglement in Hybrid Semiconductor Quantum Dot-Metal Nanoparticle System

PubMed Central

He, Yong; Zhu, Ka-Di

2017-01-01

In this paper, we review the investigation for the light-matter interaction between surface plasmon field in metal nanoparticle (MNP) and the excitons in semiconductor quantum dots (SQDs) in hybrid SQD-MNP system under the full quantum description. The exciton-plasmon interaction gives rise to the modified decay rate and the exciton energy shift which are related to the exciton energy by using a quantum transformation method. We illustrate the responses of the hybrid SQD-MNP system to external field, and reveal Fano effect shown in the absorption spectrum. We demonstrate quantum entanglement between two SQD mediated by surface plasmon field. In the absence of a laser field, concurrence of quantum entanglement will disappear after a few ns. If the laser field is present, the steady states appear, so that quantum entanglement produced will reach a steady-state entanglement. Because one of all optical pathways to induce Fano effect refers to the generation of quantum entangled states, It is shown that the concurrence of quantum entanglement can be obtained by observation for Fano effect. In a hybrid system including two MNP and a SQD, because the two Fano quantum interference processes share a segment of all optical pathways, there is correlation between the Fano effects of the two MNP. The investigations for the light-matter interaction in hybrid SQD-MNP system can pave the way for the development of the optical processing devices and quantum information based on the exciton-plasmon interaction. PMID:28632165

Simultaneous parametric generation and up-conversion of entangled optical images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saygin, M. Yu., E-mail: mihasyu@gmail.com; Chirkin, A. S., E-mail: aschirkin@rambler.r

A quantum theory of parametric amplification and frequency conversion of an optical image in coupled nonlinear optical processes that include one parametric amplification process at high-frequency pumping and two up-conversion processes in the same pump field is developed. The field momentum operator that takes into account the diffraction and group velocities of the waves is used to derive the quantum equations related to the spatial dynamics of the images during the interaction. An optical scheme for the amplification and conversion of a close image is considered. The mean photon number density and signal-to-noise ratio are calculated in the fixed-pump-field approximationmore » for images at various frequencies. It has been established that the signal-to-noise ratio decreases with increasing interaction length in the amplified image and increases in the images at the generated frequencies, tending to asymptotic values for all interacting waves. The variance of the difference of the numbers of photons is calculated for various pairs of frequencies. The quantum entanglement of the optical images formed in a high-frequency pump field is shown to be converted to higher frequencies during the generation of sum frequencies. Thus, two pairs of entangled optical images are produced in the process considered.« less

Photodissociation of quantum state-selected diatomic molecules yields new insight into ultracold chemistry

NASA Astrophysics Data System (ADS)

McDonald, Mickey; McGuyer, Bart H.; Lee, Chih-Hsi; Apfelbeck, Florian; Zelevinsky, Tanya

2016-05-01

When a molecule is subjected to a sufficiently energetic photon it can break apart into fragments through a process called ``photodissociation''. For over 70 years this simple chemical reaction has served as a vital experimental tool for acquiring information about molecular structure, since the character of the photodissociative transition can be inferred by measuring the 3D photofragment angular distribution (PAD). While theoretical understanding of this process has gradually evolved from classical considerations to a fully quantum approach, experiments to date have not yet revealed the full quantum nature of this process. In my talk I will describe recent experiments involving the photodissociation of ultracold, optical lattice-trapped, and fully quantum state-resolved 88Sr2 molecules. Optical absorption images of the PADs produced in these experiments reveal features which are inherently quantum mechanical in nature, such as matter-wave interference between output channels, and are sensitive to the quantum statistics of the molecular wavefunctions. The results of these experiments cannot be predicted using quasiclassical methods. Instead, we describe our results with a fully quantum mechanical model yielding new intuition about ultracold chemistry.

Investigation of quadratic electro-optic effects and electro-absorption process in GaN/AlGaN spherical quantum dot

PubMed Central

2014-01-01

Quadratic electro-optic effects (QEOEs) and electro-absorption (EA) process in a GaN/AlGaN spherical quantum dot are theoretically investigated. It is found that the magnitude and resonant position of third-order nonlinear optical susceptibility depend on the nanostructure size and aluminum mole fraction. With increase of the well width and barrier potential, quadratic electro-optic effect and electro-absorption process nonlinear susceptibilities are decreased and blueshifted. The results show that the DC Kerr effect in this case is much larger than that in the bulk case. Finally, it is observed that QEOEs and EA susceptibilities decrease and broaden with the decrease of relaxation time. PMID:24646318

Nonlinear optical switching and optical limiting in colloidal CdSe quantum dots investigated by nanosecond Z-scan measurement

NASA Astrophysics Data System (ADS)

Valligatla, Sreeramulu; Haldar, Krishna Kanta; Patra, Amitava; Desai, Narayana Rao

2016-10-01

The semiconductor nanocrystals are found to be promising class of third order nonlinear optical materials because of quantum confinement effects. Here, we highlight the nonlinear optical switching and optical limiting of cadmium selenide (CdSe) quantum dots (QDs) using nanosecond Z-scan measurement. The intensity dependent nonlinear absorption and nonlinear refraction of CdSe QDs were investigated by applying the Z-scan technique with 532 nm, nanosecond laser pulses. At lower intensities, the nonlinear process is dominated by saturable absorption (SA) and it is changed to reverse saturable absorption (RSA) at higher intensities. The SA behaviour is attributed to the ground state bleaching and the RSA is ascribed to free carrier absorption (FCA) of CdSe QDs. The nonlinear optical switching behaviour and reverse saturable absorption makes CdSe QDs are good candidate for all-optical device and optical limiting applications.

Nanodiamonds with photostable, sub-gigahertz linewidth quantum emitters

NASA Astrophysics Data System (ADS)

Tran, Toan Trong; Kianinia, Mehran; Bray, Kerem; Kim, Sejeong; Xu, Zai-Quan; Gentle, Angus; Sontheimer, Bernd; Bradac, Carlo; Aharonovich, Igor

2017-11-01

Single-photon emitters with narrow linewidths are highly sought after for applications in quantum information processing and quantum communications. In this letter, we report on a bright, highly polarized near infrared single photon emitter embedded in diamond nanocrystals with a narrow, sub-GHz optical linewidth at 10 K. The observed zero-phonon line at ˜780 nm is optically stable under low power excitation and blue shifts as the excitation power increases. Our results highlight the prospect for using new near infrared color centers in nanodiamonds for quantum applications.

Modeling of THz Lasers Based on Intersubband Transitions in Semiconductor Quantum Wells

NASA Technical Reports Server (NTRS)

Liu, Ansheng; Woo, Alex C. (Technical Monitor)

1999-01-01

In semiconductor quantum well structures, the intersubband energy separation can be adjusted to the terahertz (THz) frequency range by changing the well width and material combinations. The electronic and optical properties of these nanostructures can also be controlled by an applied dc electric field. These unique features lead to a large frequency tunability of the quantum well devices. In the on-going project of modeling of the THz lasers, we investigate the possibility of using optical pumping to generate THz radiation based on intersubband transitions in semiconductor quantum wells. We choose the optical pumping because in the electric current injection it is difficult to realize population inversion in the THz frequency range due to the small intersubband separation (4-40 meV). We considered both small conduction band offset (GaAs/AlGaAs) and large band offset (InGaAs/AlAsSb) quantum well structures. For GaAs/AlGaAs quantum wells, mid-infrared C02 lasers are used as pumping sources. For InGaAs/AlAsSb quantum wells, the resonant intersubband transitions can be excited by the near-infrared diode lasers. For three- and four-subband quantum wells, we solve the pumpfield-induced nonequilibrium distribution function for each subband of the quantum well system from a set of rate equations that include both intrasubband and intersubband relaxation processes. Taking into account the coherent interactions between pump and THz (signal) waves, we calculate the optical gain for the THz field. The gain arising from population inversion and stimulated Raman processes is calculated in a unified manner. A graph shows the calculated THz gain spectra for three-subband GaAs/AlGaAs quantum wells. We see that the coherent pump and signal wave interactions contribute significantly to the gain. The pump intensity dependence of the THz gain is also studied. The calculated results are shown. Because of the optical Stark effect and pump-induced population redistribution, the maximum THz gain saturates at larger pump intensities.

Quantum state detection and state preparation based on cavity-enhanced nonlinear interaction of atoms with single photon

NASA Astrophysics Data System (ADS)

Hosseini, Mahdi

Our ability to engineer quantum states of light and matter has significantly advanced over the past two decades, resulting in the production of both Gaussian and non-Gaussian optical states. The resulting tailored quantum states enable quantum technologies such as quantum optical communication, quantum sensing as well as quantum photonic computation. The strong nonlinear light-atom interaction is the key to deterministic quantum state preparation and quantum photonic processing. One route to enhancing the usually weak nonlinear light-atom interactions is to approach the regime of cavity quantum electrodynamics (cQED) interaction by means of high finesse optical resonators. I present results from the MIT experiment of large conditional cross-phase modulation between a signal photon, stored inside an atomic quantum memory, and a control photon that traverses a high-finesse optical cavity containing the atomic memory. I also present a scheme to probabilistically change the amplitude and phase of a signal photon qubit to, in principle, arbitrary values by postselection on a control photon that has interacted with that state. Notably, small changes of the control photon polarization measurement basis by few degrees can substantially change the amplitude and phase of the signal state. Finally, I present our ongoing effort at Purdue to realize similar peculiar quantum phenomena at the single photon level on chip scale photonic systems.

On the theory of quantum measurement

NASA Technical Reports Server (NTRS)

Haus, Hermann A.; Kaertner, Franz X.

1994-01-01

Many so called paradoxes of quantum mechanics are clarified when the measurement equipment is treated as a quantized system. Every measurement involves nonlinear processes. Self consistent formulations of nonlinear quantum optics are relatively simple. Hence optical measurements, such as the quantum nondemolition (QND) measurement of photon number, are particularly well suited for such a treatment. It shows that the so called 'collapse of the wave function' is not needed for the interpretation of the measurement process. Coherence of the density matrix of the signal is progressively reduced with increasing accuracy of the photon number determination. If the QND measurement is incorporated into the double slit experiment, the contrast ratio of the fringes is found to decrease with increasing information on the photon number in one of the two paths.

Coherent Pump-Probe Interactions and Terahertz Intersubband Gain in Semiconductor Quantum Wells

NASA Technical Reports Server (NTRS)

Liu, Ansheng; Ning, Cun-Zheng

1999-01-01

In recent years there has been considerable interest in intersubband-transition-based infrared semiconductor quantum well (QW) lasers because of their potential applications. In the mid-infrared range, both electrically-injected quantum cascade lasers [1] and optically-pumped multiple QW lasers [2] have been experimentally realized. In these studies, optical gain is due to population inversion between the lasing subbands. It was also proposed that stimulated Raman scattering in QW systems can produce net infrared optical gain [3j. In such a nonlinear optical scheme, the appearance of optical gain that may lead to intersubband Raman lasers does not rely on the population inversion. Since, in tile resonant Raman process (Raman gain is the largest in this case), the pump field induces population redistribution among subbands in the QW s ystem, it seems that a realistic estimate of the optical gain has to include this effect. Perturbative calculations used in the previous work [3] may overestimate the Raman gain. In this paper we present a nonperturbative calculation of terahertz gain of optically-pumped semiconductor step quantum wells. Limiting optical transitions within the conduction band of QW, we solve the pump-field-induced nonequilibrium distribution function for each subband of the QW system from a set of coupled rate equations. Both intrasubband and intersubband relaxation processes in the quantum well system are included. Taking into account the coherent interactions between pump and THz (signal) waves, we we derive the susceptibility of the QW system for the THz field. For a GaAs/AlGaAs step QW, we calculate the Thz gain spectrum for different pump frequencies and intensities. Under moderately strong pumping (approximately 0.3 MW/sq cm), a significant THz gain (approximately 300/m) is predicted. It is also shown that the coherent wave interactions (resonant stimulated Raman processes) contribute significantly to the THz gain.

Quantum-dot based nanothermometry in optical plasmonic recording media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maestro, Laura Martinez; Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122; Zhang, Qiming

2014-11-03

We report on the direct experimental determination of the temperature increment caused by laser irradiation in a optical recording media constituted by a polymeric film in which gold nanorods have been incorporated. The incorporation of CdSe quantum dots in the recording media allowed for single beam thermal reading of the on-focus temperature from a simple analysis of the two-photon excited fluorescence of quantum dots. Experimental results have been compared with numerical simulations revealing an excellent agreement and opening a promising avenue for further understanding and optimization of optical writing processes and media.

Two-dimensional spectroscopy: An approach to distinguish Förster and Dexter transfer processes in coupled nanostructures

NASA Astrophysics Data System (ADS)

Specht, Judith F.; Knorr, Andreas; Richter, Marten

2015-04-01

The linear and two-dimensional coherent optical spectra of Coulomb-coupled quantum emitters are discussed with respect to the underlying coupling processes. We present a theoretical analysis of the two different resonance energy transfer mechanisms between coupled nanostructures: Förster and Dexter interaction. Our investigation shows that the features visible in optical spectra of coupled quantum dots can be traced back to the nature of the underlying coupling mechanism (Förster or Dexter). Therefore, we discuss how the excitation transfer pathways can be controlled by choosing particular laser polarizations and mutual orientations of the quantum emitters in coherent two-dimensional spectroscopy. In this context, we analyze to what extent the delocalized double-excitonic states are bound to the optical selection rules of the uncoupled system.

Optically controlled reflection modulator using GaAs-AlGaAs n-i-p-i/multiple-quantum-well structures

NASA Technical Reports Server (NTRS)

Law, K.-K.; Simes, R. J.; Coldren, L. A.; Gossard, A. C.; Maserjian, J.

1989-01-01

An optically controlled reflection modulator has been demonstrated that consists of a combination of a GaAs-AlGaAs n-i-p-i doping structure with a multiple-quantum-well structures on top of a distributed Bragg reflector, all grown by MBE. A modulation of approximately 60 percent is obtained on the test structure, corresponding to a differential change of absorption coefficient in the quantum wells of approximately 7500/cm. Changes in reflectance can be observed with a control beam power as low as 1.5 microW. This device structure has the potential of being developed as an optically addressed spatial light modulator for optical information processing.

Generation of multiphoton entangled quantum states by means of integrated frequency combs.

PubMed

Reimer, Christian; Kues, Michael; Roztocki, Piotr; Wetzel, Benjamin; Grazioso, Fabio; Little, Brent E; Chu, Sai T; Johnston, Tudor; Bromberg, Yaron; Caspani, Lucia; Moss, David J; Morandotti, Roberto

2016-03-11

Complex optical photon states with entanglement shared among several modes are critical to improving our fundamental understanding of quantum mechanics and have applications for quantum information processing, imaging, and microscopy. We demonstrate that optical integrated Kerr frequency combs can be used to generate several bi- and multiphoton entangled qubits, with direct applications for quantum communication and computation. Our method is compatible with contemporary fiber and quantum memory infrastructures and with chip-scale semiconductor technology, enabling compact, low-cost, and scalable implementations. The exploitation of integrated Kerr frequency combs, with their ability to generate multiple, customizable, and complex quantum states, can provide a scalable, practical, and compact platform for quantum technologies. Copyright © 2016, American Association for the Advancement of Science.

Multipulse addressing of a Raman quantum memory: configurable beam splitting and efficient readout.

PubMed

Reim, K F; Nunn, J; Jin, X-M; Michelberger, P S; Champion, T F M; England, D G; Lee, K C; Kolthammer, W S; Langford, N K; Walmsley, I A

2012-06-29

Quantum memories are vital to the scalability of photonic quantum information processing (PQIP), since the storage of photons enables repeat-until-success strategies. On the other hand, the key element of all PQIP architectures is the beam splitter, which allows us to coherently couple optical modes. Here, we show how to combine these crucial functionalities by addressing a Raman quantum memory with multiple control pulses. The result is a coherent optical storage device with an extremely large time bandwidth product, that functions as an array of dynamically configurable beam splitters, and that can be read out with arbitrarily high efficiency. Networks of such devices would allow fully scalable PQIP, with applications in quantum computation, long distance quantum communications and quantum metrology.

Continuous-variable quantum computation with spatial degrees of freedom of photons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tasca, D. S.; Gomes, R. M.; Toscano, F.

2011-05-15

We discuss the use of the transverse spatial degrees of freedom of photons propagating in the paraxial approximation for continuous-variable information processing. Given the wide variety of linear optical devices available, a diverse range of operations can be performed on the spatial degrees of freedom of single photons. Here we show how to implement a set of continuous quantum logic gates which allow for universal quantum computation. In contrast with the usual quadratures of the electromagnetic field, the entire set of single-photon gates for spatial degrees of freedom does not require optical nonlinearity and, in principle, can be performed withmore » a single device: the spatial light modulator. Nevertheless, nonlinear optical processes, such as four-wave mixing, are needed in the implementation of two-photon gates. The efficiency of these gates is at present very low; however, small-scale investigations of continuous-variable quantum computation are within the reach of current technology. In this regard, we show how novel cluster states for one-way quantum computing can be produced using spontaneous parametric down-conversion.« less

Towards quantum networks of single spins: analysis of a quantum memory with an optical interface in diamond.

PubMed

Blok, M S; Kalb, N; Reiserer, A; Taminiau, T H; Hanson, R

2015-01-01

Single defect centers in diamond have emerged as a powerful platform for quantum optics experiments and quantum information processing tasks. Connecting spatially separated nodes via optical photons into a quantum network will enable distributed quantum computing and long-range quantum communication. Initial experiments on trapped atoms and ions as well as defects in diamond have demonstrated entanglement between two nodes over several meters. To realize multi-node networks, additional quantum bit systems that store quantum states while new entanglement links are established are highly desirable. Such memories allow for entanglement distillation, purification and quantum repeater protocols that extend the size, speed and distance of the network. However, to be effective, the memory must be robust against the entanglement generation protocol, which typically must be repeated many times. Here we evaluate the prospects of using carbon nuclear spins in diamond as quantum memories that are compatible with quantum networks based on single nitrogen vacancy (NV) defects in diamond. We present a theoretical framework to describe the dephasing of the nuclear spins under repeated generation of NV spin-photon entanglement and show that quantum states can be stored during hundreds of repetitions using typical experimental coupling parameters. This result demonstrates that nuclear spins with weak hyperfine couplings are promising quantum memories for quantum networks.

A scalable quantum computer with ions in an array of microtraps

PubMed

Cirac; Zoller

2000-04-06

Quantum computers require the storage of quantum information in a set of two-level systems (called qubits), the processing of this information using quantum gates and a means of final readout. So far, only a few systems have been identified as potentially viable quantum computer models--accurate quantum control of the coherent evolution is required in order to realize gate operations, while at the same time decoherence must be avoided. Examples include quantum optical systems (such as those utilizing trapped ions or neutral atoms, cavity quantum electrodynamics and nuclear magnetic resonance) and solid state systems (using nuclear spins, quantum dots and Josephson junctions). The most advanced candidates are the quantum optical and nuclear magnetic resonance systems, and we expect that they will allow quantum computing with about ten qubits within the next few years. This is still far from the numbers required for useful applications: for example, the factorization of a 200-digit number requires about 3,500 qubits, rising to 100,000 if error correction is implemented. Scalability of proposed quantum computer architectures to many qubits is thus of central importance. Here we propose a model for an ion trap quantum computer that combines scalability (a feature usually associated with solid state proposals) with the advantages of quantum optical systems (in particular, quantum control and long decoherence times).

Quantum size and magnesium composition effects on the optical absorption in the MgxZn(1-x)O/ZnO quantum well

NASA Astrophysics Data System (ADS)

Dakhlaoui, Hassen ben Bechir; Mouna, Nefzi

2018-02-01

In this work, we investigated the effects of polarizations and structural parameters on the optical absorption coefficient (OAC) and the intersubband transition between the three lowest energy levels E1,E2 , and E3 in the MgxZn(1-x)O/ZnO single quantum well. The energy of the electron in each level and its respective wavefunction are calculated by the numerical solution of Schrödinger and Poisson equations self-consistently using an effective mass approximation. Our findings exhibit that the intersubband transitions, ΔE12 and ΔE13 , can be altered and controlled by varying the quantum well width and the magnesium composition, x. Moreover, our results suggest that the optical absorption coefficients, α12 and α13 , can be modulated principally by adjusting the quantum well width, especially the optical absorption coefficient (α12), which presents a red shift by raising the quantum well thickness. Contrary to α12 , the optical absorption coefficient, α13 , can present either a red or a blue shift by increasing the quantum well width. The process responsible for this behavior, which can be suitable for optoelectronic device applications, is discussed here in detail.

Quantum Optics Models of EIT Noise and Power Broadening

NASA Astrophysics Data System (ADS)

Snider, Chad; Crescimanno, Michael; O'Leary, Shannon

2011-04-01

When two coherent beams of light interact with an atom they tend to drive the atom to a non-absorbing state through a process called Electromagnetically Induced Transparency (EIT). If the light's frequency dithers, the atom's state stochastically moves in and out of this non-absorbing state. We describe a simple quantum optics model of this process that captures the essential experimentally observed statistical features of this EIT noise, with a particular emphasis on understanding power broadening.

Two-step frequency conversion for connecting distant quantum memories by transmission through an optical fiber

NASA Astrophysics Data System (ADS)

Tamura, Shuhei; Ikeda, Kohei; Okamura, Kotaro; Yoshii, Kazumichi; Hong, Feng-Lei; Horikiri, Tomoyuki; Kosaka, Hideo

2018-06-01

Long-distance quantum communication requires entanglement between distant quantum memories. For this purpose, photon transmission is necessary to connect the distant memories. Here, for the first time, we develop a two-step frequency conversion process (from a visible wavelength to a telecommunication wavelength and back) involving the use of independent two-frequency conversion media where the target quantum memories are nitrogen-vacancy centers in diamonds (with an emission/absorption wavelength of 637.2 nm), and experimentally characterize the performance of this process acting on light from an attenuated CW laser. A total conversion efficiency of approximately 7% is achieved. The noise generated in the frequency conversion processes is measured, and the signal-to-noise ratio is estimated for a single photon signal emitted by a nitrogen-vacancy (NV) center. The developed frequency conversion system has future applications via transmission through a long optical fiber channel at a telecommunication wavelength for a quantum repeater network.

Time reversal of arbitrary photonic temporal modes via nonlinear optical frequency conversion

NASA Astrophysics Data System (ADS)

Raymer, Michael G.; Reddy, Dileep V.; van Enk, Steven J.; McKinstrie, Colin J.

2018-05-01

Single-photon wave packets can carry quantum information between nodes of a quantum network. An important general operation in photon-based quantum information systems is ‘blind’ reversal of a photon’s temporal wave packet envelope, that is, the ability to reverse an envelope without knowing the temporal state of the photon. We present an all-optical means for doing so, using nonlinear-optical frequency conversion driven by a short pump pulse. The process used may be sum-frequency generation or four-wave Bragg scattering. This scheme allows for quantum operations such as a temporal-mode parity sorter. We also verify that the scheme works for arbitrary states (not only single-photon ones) of an unknown wave packet.

Signatures of Förster and Dexter transfer processes in coupled nanostructures for linear and two-dimensional coherent optical spectroscopy

NASA Astrophysics Data System (ADS)

Specht, Judith F.; Richter, Marten

2015-03-01

In this manuscript, we study the impact of the two Coulomb induced resonance energy transfer processes, Förster and Dexter coupling, on the spectral signatures obtained by double quantum coherence spectroscopy. We show that the specific coupling characteristics allow us to identify the underlying excitation transfer mechanism by means of specific signatures in coherent spectroscopy. Therefore, we control the microscopic calculated coupling strength of spin preserving and spin flipping Förster transfer processes by varying the mutual orientation of the two quantum emitters. The calculated spectra reveal the optical selection rules altered by Förster and Dexter coupling between two semiconductor quantum dots. We show that Dexter coupling between bright and dark two-exciton states occurs.

Optical Vector Receiver Operating Near the Quantum Limit

NASA Astrophysics Data System (ADS)

Vilnrotter, V. A.; Lau, C.-W.

2005-05-01

An optical receiver concept for binary signals with performance approaching the quantum limit at low average-signal energies is developed and analyzed. A conditionally nulling receiver that reaches the quantum limit in the absence of background photons has been devised by Dolinar. However, this receiver requires ideal optical combining and complicated real-time shaping of the local field; hence, it tends to be difficult to implement at high data rates. A simpler nulling receiver that approaches the quantum limit without complex optical processing, suitable for high-rate operation, had been suggested earlier by Kennedy. Here we formulate a vector receiver concept that incorporates the Kennedy receiver with a physical beamsplitter, but it also utilizes the reflected signal component to improve signal detection. It is found that augmenting the Kennedy receiver with classical coherent detection at the auxiliary beamsplitter output, and optimally processing the vector observations, always improves on the performance of the Kennedy receiver alone, significantly so at low average-photon rates. This is precisely the region of operation where modern codes approach channel capacity. It is also shown that the addition of background radiation has little effect on the performance of the coherent receiver component, suggesting a viable approach for near-quantum-limited performance in high background environments.

Proceedings for the Alaska Meeting on Fundamental Optical Processes in Semiconductors (AMFOPS 󈧅) Held in Girdwood, Alaska on August 5-10, 2001

DTIC Science & Technology

2002-05-31

Arizona Jagdeep Shah Lucent Technologies Advisory Committee Yasuhiko Arakawa University of Tokyo David Citrin Washington State University Hartmut...the dipole moment of the exciton in the dot. WA2 Fabrication and Optical Properties of Quantum Dots: GaN-Based and InAs Quantum Dots Yasuhiko

Deterministic reshaping of single-photon spectra using cross-phase modulation.

PubMed

Matsuda, Nobuyuki

2016-03-01

The frequency conversion of light has proved to be a crucial technology for communication, spectroscopy, imaging, and signal processing. In the quantum regime, it also offers great potential for realizing quantum networks incorporating disparate physical systems and quantum-enhanced information processing over a large computational space. The frequency conversion of quantum light, such as single photons, has been extensively investigated for the last two decades using all-optical frequency mixing, with the ultimate goal of realizing lossless and noiseless conversion. I demonstrate another route to this target using frequency conversion induced by cross-phase modulation in a dispersion-managed photonic crystal fiber. Owing to the deterministic and all-optical nature of the process, the lossless and low-noise spectral reshaping of a single-photon wave packet in the telecommunication band has been readily achieved with a modulation bandwidth as large as 0.4 THz. I further demonstrate that the scheme is applicable to manipulations of a nonclassical frequency correlation, wave packet interference, and entanglement between two photons. This approach presents a new coherent frequency interface for photons for quantum information processing.

Deterministic reshaping of single-photon spectra using cross-phase modulation

PubMed Central

Matsuda, Nobuyuki

2016-01-01

The frequency conversion of light has proved to be a crucial technology for communication, spectroscopy, imaging, and signal processing. In the quantum regime, it also offers great potential for realizing quantum networks incorporating disparate physical systems and quantum-enhanced information processing over a large computational space. The frequency conversion of quantum light, such as single photons, has been extensively investigated for the last two decades using all-optical frequency mixing, with the ultimate goal of realizing lossless and noiseless conversion. I demonstrate another route to this target using frequency conversion induced by cross-phase modulation in a dispersion-managed photonic crystal fiber. Owing to the deterministic and all-optical nature of the process, the lossless and low-noise spectral reshaping of a single-photon wave packet in the telecommunication band has been readily achieved with a modulation bandwidth as large as 0.4 THz. I further demonstrate that the scheme is applicable to manipulations of a nonclassical frequency correlation, wave packet interference, and entanglement between two photons. This approach presents a new coherent frequency interface for photons for quantum information processing. PMID:27051862

Strongly Cavity-Enhanced Spontaneous Emission from Silicon-Vacancy Centers in Diamond

DOE PAGES

Zhang, Jingyuan Linda; Sun, Shuo; Burek, Michael J.; ...

2018-01-29

Quantum emitters are an integral component for a broad range of quantum technologies, including quantum communication, quantum repeaters, and linear optical quantum computation. Solid-state color centers are promising candidates for scalable quantum optics due to their long coherence time and small inhomogeneous broadening. However, once excited, color centers often decay through phonon-assisted processes, limiting the efficiency of single-photon generation and photon-mediated entanglement generation. Herein, we demonstrate strong enhancement of spontaneous emission rate of a single silicon-vacancy center in diamond embedded within a monolithic optical cavity, reaching a regime in which the excited-state lifetime is dominated by spontaneous emission into themore » cavity mode. We observe 10-fold lifetime reduction and 42-fold enhancement in emission intensity when the cavity is tuned into resonance with the optical transition of a single silicon-vacancy center, corresponding to 90% of the excited-state energy decay occurring through spontaneous emission into the cavity mode. Here, we also demonstrate the largest coupling strength ( g/2π = 4.9 ± 0.3 GHz) and cooperativity ( C = 1.4) to date for color-center-based cavity quantum electrodynamics systems, bringing the system closer to the strong coupling regime.« less

Strongly Cavity-Enhanced Spontaneous Emission from Silicon-Vacancy Centers in Diamond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jingyuan Linda; Sun, Shuo; Burek, Michael J.

Quantum emitters are an integral component for a broad range of quantum technologies, including quantum communication, quantum repeaters, and linear optical quantum computation. Solid-state color centers are promising candidates for scalable quantum optics due to their long coherence time and small inhomogeneous broadening. However, once excited, color centers often decay through phonon-assisted processes, limiting the efficiency of single-photon generation and photon-mediated entanglement generation. Herein, we demonstrate strong enhancement of spontaneous emission rate of a single silicon-vacancy center in diamond embedded within a monolithic optical cavity, reaching a regime in which the excited-state lifetime is dominated by spontaneous emission into themore » cavity mode. We observe 10-fold lifetime reduction and 42-fold enhancement in emission intensity when the cavity is tuned into resonance with the optical transition of a single silicon-vacancy center, corresponding to 90% of the excited-state energy decay occurring through spontaneous emission into the cavity mode. Here, we also demonstrate the largest coupling strength ( g/2π = 4.9 ± 0.3 GHz) and cooperativity ( C = 1.4) to date for color-center-based cavity quantum electrodynamics systems, bringing the system closer to the strong coupling regime.« less

Optical investigation of carrier tunneling in semiconductor nanostructures

NASA Astrophysics Data System (ADS)

Emiliani, V.; Ceccherini, S.; Bogani, F.; Colocci, M.; Frova, A.; Shi, Song Stone

1997-08-01

The tunneling dynamics of excitons and free carriers in AlxGa1-xAs/GaAs asymmetric double quantum well and near-surface quantum well structures has been investigated by means of time-resolved optical techniques. The competing processes of carrier tunneling out of the quantum well and exciton formation and recombination inside the quantum well have been thoroughly studied in the range of the excitation densities relevant to device applications. A consistent picture capable of fully describing the carrier and exciton-tunneling mechanisms in both types of structures has been obtained and apparently contrasting results in the recent literature are clarified.

Theoretical Investigation of Optical Detection and Recognition of Single Biological Molecules Using Coherent Dynamics of Exciton-Plasmon Coupling

PubMed Central

Sadeghi, S. M.; Hood, B.; Patty, K. D.; Mao, C.-B.

2013-01-01

We use quantum coherence in a system consisting of one metallic nanorod and one semi-conductor quantum dot to investigate a plasmonic nanosensor capable of digital optical detection and recognition of single biological molecules. In such a sensor the adsorption of a specific molecule to the nanorod turns off the emission of the system when it interacts with an optical pulse having a certain intensity and temporal width. The proposed quantum sensors can count the number of molecules of the same type or differentiate between molecule types with digital optical signals that can be measured with high certainty. We show that these sensors are based on the ultrafast upheaval of coherent dynamics of the system and the removal of coherent blockage of energy transfer from the quantum dot to the nanorod once the adsorption process has occurred. PMID:24040424

Remote creation of hybrid entanglement between particle-like and wave-like optical qubits

NASA Astrophysics Data System (ADS)

Morin, Olivier; Huang, Kun; Liu, Jianli; Le Jeannic, Hanna; Fabre, Claude; Laurat, Julien

2014-07-01

The wave-particle duality of light has led to two different encodings for optical quantum information processing. Several approaches have emerged based either on particle-like discrete-variable states (that is, finite-dimensional quantum systems) or on wave-like continuous-variable states (that is, infinite-dimensional systems). Here, we demonstrate the generation of entanglement between optical qubits of these different types, located at distant places and connected by a lossy channel. Such hybrid entanglement, which is a key resource for a variety of recently proposed schemes, including quantum cryptography and computing, enables information to be converted from one Hilbert space to the other via teleportation and therefore the connection of remote quantum processors based upon different encodings. Beyond its fundamental significance for the exploration of entanglement and its possible instantiations, our optical circuit holds promise for implementations of heterogeneous network, where discrete- and continuous-variable operations and techniques can be efficiently combined.

Hybrid Toffoli gate on photons and quantum spins

PubMed Central

Luo, Ming-Xing; Ma, Song-Ya; Chen, Xiu-Bo; Wang, Xiaojun

2015-01-01

Quantum computation offers potential advantages in solving a number of interesting and difficult problems. Several controlled logic gates, the elemental building blocks of quantum computer, have been realized with various physical systems. A general technique was recently proposed that significantly reduces the realization complexity of multiple-control logic gates by harnessing multi-level information carriers. We present implementations of a key quantum circuit: the three-qubit Toffoli gate. By exploring the optical selection rules of one-sided optical microcavities, a Toffoli gate may be realized on all combinations of photon and quantum spins in the QD-cavity. The three general controlled-NOT gates are involved using an auxiliary photon with two degrees of freedom. Our results show that photons and quantum spins may be used alternatively in quantum information processing. PMID:26568078

Hybrid Toffoli gate on photons and quantum spins.

PubMed

Luo, Ming-Xing; Ma, Song-Ya; Chen, Xiu-Bo; Wang, Xiaojun

2015-11-16

Quantum computation offers potential advantages in solving a number of interesting and difficult problems. Several controlled logic gates, the elemental building blocks of quantum computer, have been realized with various physical systems. A general technique was recently proposed that significantly reduces the realization complexity of multiple-control logic gates by harnessing multi-level information carriers. We present implementations of a key quantum circuit: the three-qubit Toffoli gate. By exploring the optical selection rules of one-sided optical microcavities, a Toffoli gate may be realized on all combinations of photon and quantum spins in the QD-cavity. The three general controlled-NOT gates are involved using an auxiliary photon with two degrees of freedom. Our results show that photons and quantum spins may be used alternatively in quantum information processing.

Frequency-domain Hong-Ou-Mandel interference with linear optics.

PubMed

Imany, Poolad; Odele, Ogaga D; Alshaykh, Mohammed S; Lu, Hsuan-Hao; Leaird, Daniel E; Weiner, Andrew M

2018-06-15

The Hong-Ou-Mandel (HOM) interference is one of the most fundamental quantum-mechanical effects that reveal a nonclassical behavior of single photons. Two identical photons that are incident on the input ports of an unbiased beam splitter always exit the beam splitter together from the same output port, an effect referred to as photon bunching. In this Letter, we utilize a single electro-optic phase modulator as a probabilistic frequency beam splitter, which we exploit to observe HOM interference between two photons that are in different spectral modes, yet are identical in other characteristics. Our approach enables linear optical quantum information processing protocols using the frequency degree of freedom in photons such as quantum computing techniques with linear optics.

Absorption spectra and optical transitions in InAs/GaAs self-assembled quantum dots

NASA Astrophysics Data System (ADS)

Cusack, M. A.; Briddon, P. R.; Jaros, M.

1997-08-01

We have applied the multiband effective mass/valence force field method to the calculation of optical transitions and absorption spectra in InAs/GaAs self-organized dots of different sizes. We have found that the apparently conflicting assignments of luminescence features to optical transitions in different experiments are in fact entirely compatible with each other. Whether the optical signature of a dot is constructed from transitions between states of the same quantum numbers, or via additional processes between the ground conduction state and a low-lying valence state depends on the aspect ratio of the quantum dot radius and height. The states involved can be predicted from a simple particle in a rigid rectangular box model.

How to decompose arbitrary continuous-variable quantum operations.

PubMed

Sefi, Seckin; van Loock, Peter

2011-10-21

We present a general, systematic, and efficient method for decomposing any given exponential operator of bosonic mode operators, describing an arbitrary multimode Hamiltonian evolution, into a set of universal unitary gates. Although our approach is mainly oriented towards continuous-variable quantum computation, it may be used more generally whenever quantum states are to be transformed deterministically, e.g., in quantum control, discrete-variable quantum computation, or Hamiltonian simulation. We illustrate our scheme by presenting decompositions for various nonlinear Hamiltonians including quartic Kerr interactions. Finally, we conclude with two potential experiments utilizing offline-prepared optical cubic states and homodyne detections, in which quantum information is processed optically or in an atomic memory using quadratic light-atom interactions. © 2011 American Physical Society

Quantum filtering for multiple diffusive and Poissonian measurements

NASA Astrophysics Data System (ADS)

Emzir, Muhammad F.; Woolley, Matthew J.; Petersen, Ian R.

2015-09-01

We provide a rigorous derivation of a quantum filter for the case of multiple measurements being made on a quantum system. We consider a class of measurement processes which are functions of bosonic field operators, including combinations of diffusive and Poissonian processes. This covers the standard cases from quantum optics, where homodyne detection may be described as a diffusive process and photon counting may be described as a Poissonian process. We obtain a necessary and sufficient condition for any pair of such measurements taken at different output channels to satisfy a commutation relationship. Then, we derive a general, multiple-measurement quantum filter as an extension of a single-measurement quantum filter. As an application we explicitly obtain the quantum filter corresponding to homodyne detection and photon counting at the output ports of a beam splitter.

Light sensitive memristor with bi-directional and wavelength-dependent conductance control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maier, P.; Hartmann, F., E-mail: fabian.hartmann@physik.uni-wuerzburg.de; Emmerling, M.

2016-07-11

We report the optical control of localized charge on positioned quantum dots in an electro-photo-sensitive memristor. Interband absorption processes in the quantum dot barrier matrix lead to photo-generated electron-hole-pairs that, depending on the applied bias voltage, charge or discharge the quantum dots and hence decrease or increase the conductance. Wavelength-dependent conductance control is observed by illumination with red and infrared light, which leads to charging via interband and discharging via intraband absorption. The presented memristor enables optical conductance control and may thus be considered for sensory applications in artificial neural networks as light-sensitive synapses or optically tunable memories.

Quantum Computation Using Optically Coupled Quantum Dot Arrays

NASA Technical Reports Server (NTRS)

Pradhan, Prabhakar; Anantram, M. P.; Wang, K. L.; Roychowhury, V. P.; Saini, Subhash (Technical Monitor)

1998-01-01

A solid state model for quantum computation has potential advantages in terms of the ease of fabrication, characterization, and integration. The fundamental requirements for a quantum computer involve the realization of basic processing units (qubits), and a scheme for controlled switching and coupling among the qubits, which enables one to perform controlled operations on qubits. We propose a model for quantum computation based on optically coupled quantum dot arrays, which is computationally similar to the atomic model proposed by Cirac and Zoller. In this model, individual qubits are comprised of two coupled quantum dots, and an array of these basic units is placed in an optical cavity. Switching among the states of the individual units is done by controlled laser pulses via near field interaction using the NSOM technology. Controlled rotations involving two or more qubits are performed via common cavity mode photon. We have calculated critical times, including the spontaneous emission and switching times, and show that they are comparable to the best times projected for other proposed models of quantum computation. We have also shown the feasibility of accessing individual quantum dots using the NSOM technology by calculating the photon density at the tip, and estimating the power necessary to perform the basic controlled operations. We are currently in the process of estimating the decoherence times for this system; however, we have formulated initial arguments which seem to indicate that the decoherence times will be comparable, if not longer, than many other proposed models.

Testing ultrafast mode-locking at microhertz relative optical linewidth.

PubMed

Martin, Michael J; Foreman, Seth M; Schibli, T R; Ye, Jun

2009-01-19

We report new limits on the phase coherence of the ultrafast mode-locking process in an octave-spanning Ti:sapphire comb.We find that the mode-locking mechanism correlates optical phase across a full optical octave with less than 2.5 microHZ relative linewidth. This result is at least two orders of magnitude below recent predictions for quantum-limited individual comb-mode linewidths, verifying that the mode-locking mechanism strongly correlates quantum noise across the comb spectrum.

Quantum storage of entangled telecom-wavelength photons in an erbium-doped optical fibre

NASA Astrophysics Data System (ADS)

Saglamyurek, Erhan; Jin, Jeongwan; Verma, Varun B.; Shaw, Matthew D.; Marsili, Francesco; Nam, Sae Woo; Oblak, Daniel; Tittel, Wolfgang

2015-02-01

The realization of a future quantum Internet requires the processing and storage of quantum information at local nodes and interconnecting distant nodes using free-space and fibre-optic links. Quantum memories for light are key elements of such quantum networks. However, to date, neither an atomic quantum memory for non-classical states of light operating at a wavelength compatible with standard telecom fibre infrastructure, nor a fibre-based implementation of a quantum memory, has been reported. Here, we demonstrate the storage and faithful recall of the state of a 1,532 nm wavelength photon entangled with a 795 nm photon, in an ensemble of cryogenically cooled erbium ions doped into a 20-m-long silica fibre, using a photon-echo quantum memory protocol. Despite its currently limited efficiency and storage time, our broadband light-matter interface brings fibre-based quantum networks one step closer to reality.

Complete quantum control of a single quantum dot spin using ultrafast optical pulses.

PubMed

Press, David; Ladd, Thaddeus D; Zhang, Bingyang; Yamamoto, Yoshihisa

2008-11-13

A basic requirement for quantum information processing systems is the ability to completely control the state of a single qubit. For qubits based on electron spin, a universal single-qubit gate is realized by a rotation of the spin by any angle about an arbitrary axis. Driven, coherent Rabi oscillations between two spin states can be used to demonstrate control of the rotation angle. Ramsey interference, produced by two coherent spin rotations separated by a variable time delay, demonstrates control over the axis of rotation. Full quantum control of an electron spin in a quantum dot has previously been demonstrated using resonant radio-frequency pulses that require many spin precession periods. However, optical manipulation of the spin allows quantum control on a picosecond or femtosecond timescale, permitting an arbitrary rotation to be completed within one spin precession period. Recent work in optical single-spin control has demonstrated the initialization of a spin state in a quantum dot, as well as the ultrafast manipulation of coherence in a largely unpolarized single-spin state. Here we demonstrate complete coherent control over an initialized electron spin state in a quantum dot using picosecond optical pulses. First we vary the intensity of a single optical pulse to observe over six Rabi oscillations between the two spin states; then we apply two sequential pulses to observe high-contrast Ramsey interference. Such a two-pulse sequence realizes an arbitrary single-qubit gate completed on a picosecond timescale. Along with the spin initialization and final projective measurement of the spin state, these results demonstrate a complete set of all-optical single-qubit operations.

Coherent all-optical control of ultracold atoms arrays in permanent magnetic traps.

PubMed

Abdelrahman, Ahmed; Mukai, Tetsuya; Häffner, Hartmut; Byrnes, Tim

2014-02-10

We propose a hybrid architecture for quantum information processing based on magnetically trapped ultracold atoms coupled via optical fields. The ultracold atoms, which can be either Bose-Einstein condensates or ensembles, are trapped in permanent magnetic traps and are placed in microcavities, connected by silica based waveguides on an atom chip structure. At each trapping center, the ultracold atoms form spin coherent states, serving as a quantum memory. An all-optical scheme is used to initialize, measure and perform a universal set of quantum gates on the single and two spin-coherent states where entanglement can be generated addressably between spatially separated trapped ultracold atoms. This allows for universal quantum operations on the spin coherent state quantum memories. We give detailed derivations of the composite cavity system mediated by a silica waveguide as well as the control scheme. Estimates for the necessary experimental conditions for a working hybrid device are given.

A homodyne detector integrated onto a photonic chip for measuring quantum states and generating random numbers

NASA Astrophysics Data System (ADS)

Raffaelli, Francesco; Ferranti, Giacomo; Mahler, Dylan H.; Sibson, Philip; Kennard, Jake E.; Santamato, Alberto; Sinclair, Gary; Bonneau, Damien; Thompson, Mark G.; Matthews, Jonathan C. F.

2018-04-01

Optical homodyne detection has found use as a characterisation tool in a range of quantum technologies. So far implementations have been limited to bulk optics. Here we present the optical integration of a homodyne detector onto a silicon photonics chip. The resulting device operates at high speed, up 150 MHz, it is compact and it operates with low noise, quantified with 11 dB clearance between shot noise and electronic noise. We perform on-chip quantum tomography of coherent states with the detector and show that it meets the requirements for characterising more general quantum states of light. We also show that the detector is able to produce quantum random numbers at a rate of 1.2 Gbps, by measuring the vacuum state of the electromagnetic field and applying off-line post processing. The produced random numbers pass all the statistical tests provided by the NIST test suite.

RADIANCE AND PHOTON NOISE: Imaging in geometrical optics, physical optics, quantum optics and radiology.

PubMed

Barrett, Harrison H; Myers, Kyle J; Caucci, Luca

2014-08-17

A fundamental way of describing a photon-limited imaging system is in terms of a Poisson random process in spatial, angular and wavelength variables. The mean of this random process is the spectral radiance. The principle of conservation of radiance then allows a full characterization of the noise in the image (conditional on viewing a specified object). To elucidate these connections, we first review the definitions and basic properties of radiance as defined in terms of geometrical optics, radiology, physical optics and quantum optics. The propagation and conservation laws for radiance in each of these domains are reviewed. Then we distinguish four categories of imaging detectors that all respond in some way to the incident radiance, including the new category of photon-processing detectors. The relation between the radiance and the statistical properties of the detector output is discussed and related to task-based measures of image quality and the information content of a single detected photon.

RADIANCE AND PHOTON NOISE: Imaging in geometrical optics, physical optics, quantum optics and radiology

PubMed Central

Barrett, Harrison H.; Myers, Kyle J.; Caucci, Luca

2016-01-01

A fundamental way of describing a photon-limited imaging system is in terms of a Poisson random process in spatial, angular and wavelength variables. The mean of this random process is the spectral radiance. The principle of conservation of radiance then allows a full characterization of the noise in the image (conditional on viewing a specified object). To elucidate these connections, we first review the definitions and basic properties of radiance as defined in terms of geometrical optics, radiology, physical optics and quantum optics. The propagation and conservation laws for radiance in each of these domains are reviewed. Then we distinguish four categories of imaging detectors that all respond in some way to the incident radiance, including the new category of photon-processing detectors. The relation between the radiance and the statistical properties of the detector output is discussed and related to task-based measures of image quality and the information content of a single detected photon. PMID:27478293

Selective Processing Techniques for Electronics and Opto-Electronic Applications: Quantum-Well Devices and Integrated Optic Circuits

DTIC Science & Technology

1993-02-10

new technology is to have sufficient control of processing to *- describable by an appropriate elecromagnetic model . build useful devices. For example...3. W aveguide Modulators .................................. 7 B. Integrated Optical Device and Circuit Modeling ... ................... .. 10 C...following categories: A. Integrated Optical Devices and Technology B. Integrated Optical Device and Circuit Modeling C. Cryogenic Etching for Low

Low-photon-number optical switch and AND/OR logic gates based on quantum dot-bimodal cavity coupling system.

PubMed

Ma, Shen; Ye, Han; Yu, Zhong-Yuan; Zhang, Wen; Peng, Yi-Wei; Cheng, Xiang; Liu, Yu-Min

2016-01-11

We propose a new scheme based on quantum dot-bimodal cavity coupling system to realize all-optical switch and logic gates in low-photon-number regime. Suppression of mode transmission due to the destructive interference effect is theoretically demonstrated by driving the cavity with two orthogonally polarized pulsed lasers at certain pulse delay. The transmitted mode can be selected by designing laser pulse sequence. The optical switch with high on-off ratio emerges when considering one driving laser as the control. Moreover, the AND/OR logic gates based on photon polarization are achieved by cascading the coupling system. Both proposed optical switch and logic gates work well in ultra-low energy magnitude. Our work may enable various applications of all-optical computing and quantum information processing.

Low-photon-number optical switch and AND/OR logic gates based on quantum dot-bimodal cavity coupling system

PubMed Central

Ma, Shen; Ye, Han; Yu, Zhong-Yuan; Zhang, Wen; Peng, Yi-Wei; Cheng, Xiang; Liu, Yu-Min

2016-01-01

We propose a new scheme based on quantum dot-bimodal cavity coupling system to realize all-optical switch and logic gates in low-photon-number regime. Suppression of mode transmission due to the destructive interference effect is theoretically demonstrated by driving the cavity with two orthogonally polarized pulsed lasers at certain pulse delay. The transmitted mode can be selected by designing laser pulse sequence. The optical switch with high on-off ratio emerges when considering one driving laser as the control. Moreover, the AND/OR logic gates based on photon polarization are achieved by cascading the coupling system. Both proposed optical switch and logic gates work well in ultra-low energy magnitude. Our work may enable various applications of all-optical computing and quantum information processing. PMID:26750557

Trapping photons on the line: controllable dynamics of a quantum walk

NASA Astrophysics Data System (ADS)

Xue, Peng; Qin, Hao; Tang, Bao

2014-04-01

Optical interferometers comprising birefringent-crystal beam displacers, wave plates, and phase shifters serve as stable devices for simulating quantum information processes such as heralded coined quantum walks. Quantum walks are important for quantum algorithms, universal quantum computing circuits, quantum transport in complex systems, and demonstrating intriguing nonlinear dynamical quantum phenomena. We introduce fully controllable polarization-independent phase shifters in optical pathes in order to realize site-dependent phase defects. The effectiveness of our interferometer is demonstrated through realizing single-photon quantum-walk dynamics in one dimension. By applying site-dependent phase defects, the translational symmetry of an ideal standard quantum walk is broken resulting in localization effect in a quantum walk architecture. The walk is realized for different site-dependent phase defects and coin settings, indicating the strength of localization signature depends on the level of phase due to site-dependent phase defects and coin settings and opening the way for the implementation of a quantum-walk-based algorithm.

Integrated nonlinear photonics. Emerging applications and ongoing challenges - A mini review

DOE PAGES

Hendrickson, Scott M.; Foster, Amy C.; Camacho, Ryan M.; ...

2014-11-26

In this paper, we provide a review of recent progress in integrated nonlinear photonics with a focus on emerging applications in all-optical signal processing, ultra-low-power all-optical switching, and quantum information processing.

Holographic storage of biphoton entanglement.

PubMed

Dai, Han-Ning; Zhang, Han; Yang, Sheng-Jun; Zhao, Tian-Ming; Rui, Jun; Deng, You-Jin; Li, Li; Liu, Nai-Le; Chen, Shuai; Bao, Xiao-Hui; Jin, Xian-Min; Zhao, Bo; Pan, Jian-Wei

2012-05-25

Coherent and reversible storage of multiphoton entanglement with a multimode quantum memory is essential for scalable all-optical quantum information processing. Although a single photon has been successfully stored in different quantum systems, storage of multiphoton entanglement remains challenging because of the critical requirement for coherent control of the photonic entanglement source, multimode quantum memory, and quantum interface between them. Here we demonstrate a coherent and reversible storage of biphoton Bell-type entanglement with a holographic multimode atomic-ensemble-based quantum memory. The retrieved biphoton entanglement violates the Bell inequality for 1 μs storage time and a memory-process fidelity of 98% is demonstrated by quantum state tomography.

Quantum optical measurement with tripartite entangled photons generated by triple parametric down-conversion

NASA Astrophysics Data System (ADS)

Cho, Minhaeng

2018-05-01

Parametric down-conversion is a second-order nonlinear optical process annihilating a pump photon and creating a pair of photons in the signal and idler modes. Then, by using two parametric down-converters and introducing a path indistinguishability for the two generated idler modes, a quantum coherence between two conjugate signal beams can be induced. Such a double spontaneous or stimulated parametric down-conversion scheme has been used to demonstrate quantum spectroscopy and imaging with undetected idler photons via measuring one-photon interference between their correlated signal beams. Recently, we considered another quantum optical measurement scheme utilizing W-type tripartite entangled signal photons that can be generated by employing three spontaneous parametric down-conversion crystals and by inducing coherences or path-indistinguishabilities between their correlated idler beams and between quantum vacuum fields. Here, we consider an extended triple stimulated parametric down-conversion scheme for quantum optical measurement of sample properties with undetected idler and photons. Noting the real effect of vacuum field indistinguishability on the fringe visibility as well as the role of zero-point field energy in the interferometry, we show that this scheme is an ideal and efficient way to create a coherent state of W-type entangled signal photons. We anticipate that this scheme would be of critical use in further developing quantum optical measurements in spectroscopy and microscopy with undetected photons.

Quantum optical measurement with tripartite entangled photons generated by triple parametric down-conversion.

PubMed

Cho, Minhaeng

2018-05-14

Parametric down-conversion is a second-order nonlinear optical process annihilating a pump photon and creating a pair of photons in the signal and idler modes. Then, by using two parametric down-converters and introducing a path indistinguishability for the two generated idler modes, a quantum coherence between two conjugate signal beams can be induced. Such a double spontaneous or stimulated parametric down-conversion scheme has been used to demonstrate quantum spectroscopy and imaging with undetected idler photons via measuring one-photon interference between their correlated signal beams. Recently, we considered another quantum optical measurement scheme utilizing W-type tripartite entangled signal photons that can be generated by employing three spontaneous parametric down-conversion crystals and by inducing coherences or path-indistinguishabilities between their correlated idler beams and between quantum vacuum fields. Here, we consider an extended triple stimulated parametric down-conversion scheme for quantum optical measurement of sample properties with undetected idler and photons. Noting the real effect of vacuum field indistinguishability on the fringe visibility as well as the role of zero-point field energy in the interferometry, we show that this scheme is an ideal and efficient way to create a coherent state of W-type entangled signal photons. We anticipate that this scheme would be of critical use in further developing quantum optical measurements in spectroscopy and microscopy with undetected photons.

Polarized linewidth-controllable double-trapping electromagnetically induced transparency spectra in a resonant plasmon nanocavity

PubMed Central

Wang, Luojia; Gu, Ying; Chen, Hongyi; Zhang, Jia-Yu; Cui, Yiping; Gerardot, Brian D.; Gong, Qihuang

2013-01-01

Surface plasmons with ultrasmall optical mode volume and strong near field enhancement can be used to realize nanoscale light-matter interaction. Combining surface plasmons with the quantum system provides the possibility of nanoscale realization of important quantum optical phenomena, including the electromagnetically induced transparency (EIT), which has many applications in nonlinear quantum optics and quantum information processing. Here, using a custom-designed resonant plasmon nanocavity, we demonstrate polarized position-dependent linewidth-controllable EIT spectra at the nanoscale. We analytically obtain the double coherent population trapping conditions in a double-Λ quantum system with crossing damping, which give two transparent points in the EIT spectra. The linewidths of the three peaks are extremely sensitive to the level spacing of the excited states, the Rabi frequencies and detunings of pump fields, and the Purcell factors. In particular the linewidth of the central peak is exceptionally narrow. The hybrid system may have potential applications in ultra-compact plasmon-quantum devices. PMID:24096943

Complete quantum control of exciton qubits bound to isoelectronic centres.

PubMed

Éthier-Majcher, G; St-Jean, P; Boso, G; Tosi, A; Klem, J F; Francoeur, S

2014-05-30

In recent years, impressive demonstrations related to quantum information processing have been realized. The scalability of quantum interactions between arbitrary qubits within an array remains however a significant hurdle to the practical realization of a quantum computer. Among the proposed ideas to achieve fully scalable quantum processing, the use of photons is appealing because they can mediate long-range quantum interactions and could serve as buses to build quantum networks. Quantum dots or nitrogen-vacancy centres in diamond can be coupled to light, but the former system lacks optical homogeneity while the latter suffers from a low dipole moment, rendering their large-scale interconnection challenging. Here, through the complete quantum control of exciton qubits, we demonstrate that nitrogen isoelectronic centres in GaAs combine both the uniformity and predictability of atomic defects and the dipole moment of semiconductor quantum dots. This establishes isoelectronic centres as a promising platform for quantum information processing.

The Physics of Ultracold Sr2 Molecules: Optical Production and Precision Measurement

NASA Astrophysics Data System (ADS)

Osborn, Christopher Butler

Colloidal quantum dots have desirable optical properties which can be exploited to realize a variety of photonic devices and functionalities. However, colloidal dots have not had a pervasive utility in photonic devices because of the absence of patterning methods. The electronic chip industry is highly successful due to the well-established lithographic procedures. In this thesis we borrow ideas from the semiconductor industry to develop lithographic techniques that can be used to pattern colloidal quantum dots while ensuring that the optical properties of the quantum dots are not affected by the process. In this thesis we have developed colloidal quantum dot based waveguide structures for amplification and switching applications for all-optical signal processing. We have also developed colloidal quantum dot based light emitting diodes. We successfully introduced CdSe/ZnS quantum dots into a UV curable photo-resist, which was then patterned to realize active devices. In addition, "passive" devices (devices without quantum dots) were integrated to "active" devices via waveguide couplers. Use of photo-resist devices offers two distinct advantages. First, they have low scattering loss and secondly, they allow good fiber to waveguide coupling efficiency due to the low refractive index which allows for large waveguide cross-sections while supporting single mode operation. Practical planar photonic devices and circuits incorporating both active and passive structures can now be realized, now that we have patterning capabilities of quantum dots while maintaining the original optical attributes of the system. In addition to the photo-resist host, we also explored the incorporation of colloidal quantum dots into a dielectric silicon dioxide and silicon nitride one-dimensional microcavity structures using low temperature plasma enhanced chemical vapor deposition. This material system can be used to realize microcavity light emitting diodes that can be realized on any substrate. As a proof of concept demonstration we show a 1550 nm emitting all-dielectric vertical cavity structure embedded with PbS quantum dots. Enhancement in spontaneous emission from the dots embedded in the microcavity is also demonstrated.

Quantum communication and information processing

NASA Astrophysics Data System (ADS)

Beals, Travis Roland

Quantum computers enable dramatically more efficient algorithms for solving certain classes of computational problems, but, in doing so, they create new problems. In particular, Shor's Algorithm allows for efficient cryptanalysis of many public-key cryptosystems. As public key cryptography is a critical component of present-day electronic commerce, it is crucial that a working, secure replacement be found. Quantum key distribution (QKD), first developed by C.H. Bennett and G. Brassard, offers a partial solution, but many challenges remain, both in terms of hardware limitations and in designing cryptographic protocols for a viable large-scale quantum communication infrastructure. In Part I, I investigate optical lattice-based approaches to quantum information processing. I look at details of a proposal for an optical lattice-based quantum computer, which could potentially be used for both quantum communications and for more sophisticated quantum information processing. In Part III, I propose a method for converting and storing photonic quantum bits in the internal state of periodically-spaced neutral atoms by generating and manipulating a photonic band gap and associated defect states. In Part II, I present a cryptographic protocol which allows for the extension of present-day QKD networks over much longer distances without the development of new hardware. I also present a second, related protocol which effectively solves the authentication problem faced by a large QKD network, thus making QKD a viable, information-theoretic secure replacement for public key cryptosystems.

Quantum measurement-induced dynamics of many-body ultracold bosonic and fermionic systems in optical lattices

NASA Astrophysics Data System (ADS)

Mazzucchi, Gabriel; Kozlowski, Wojciech; Caballero-Benitez, Santiago F.; Elliott, Thomas J.; Mekhov, Igor B.

2016-02-01

Trapping ultracold atoms in optical lattices enabled numerous breakthroughs uniting several disciplines. Coupling these systems to quantized light leads to a plethora of new phenomena and has opened up a new field of study. Here we introduce an unusual additional source of competition in a many-body strongly correlated system: We prove that quantum backaction of global measurement is able to efficiently compete with intrinsic short-range dynamics of an atomic system. The competition becomes possible due to the ability to change the spatial profile of a global measurement at a microscopic scale comparable to the lattice period without the need of single site addressing. In coherence with a general physical concept, where new competitions typically lead to new phenomena, we demonstrate nontrivial dynamical effects such as large-scale multimode oscillations, long-range entanglement, and correlated tunneling, as well as selective suppression and enhancement of dynamical processes beyond the projective limit of the quantum Zeno effect. We demonstrate both the breakup and protection of strongly interacting fermion pairs by measurement. Such a quantum optical approach introduces into many-body physics novel processes, objects, and methods of quantum engineering, including the design of many-body entangled environments for open systems.

EDITORIAL: Squeezed states and uncertainty relations

NASA Astrophysics Data System (ADS)

Jauregue-Renaud, Rocio; Kim, Young S.; Man'ko, Margarita A.; Moya-Cessa, Hector

2004-06-01

This special issue of Journal of Optics B: Quantum and Semiclassical Optics is composed mainly of extended versions of talks and papers presented at the Eighth International Conference on Squeezed States and Uncertainty Relations held in Puebla, Mexico on 9-13 June 2003. The Conference was hosted by Instituto de Astrofísica, Óptica y Electrónica, and the Universidad Nacional Autónoma de México. This series of meetings began at the University of Maryland, College Park, USA, in March 1991. The second and third workshops were organized by the Lebedev Physical Institute in Moscow, Russia, in 1992 and by the University of Maryland Baltimore County, USA, in 1993, respectively. Afterwards, it was decided that the workshop series should be held every two years. Thus the fourth meeting took place at the University of Shanxi in China and was supported by the International Union of Pure and Applied Physics (IUPAP). The next three meetings in 1997, 1999 and 2001 were held in Lake Balatonfüred, Hungary, in Naples, Italy, and in Boston, USA, respectively. All of them were sponsored by IUPAP. The ninth workshop will take place in Besançon, France, in 2005. The conference has now become one of the major international meetings on quantum optics and the foundations of quantum mechanics, where most of the active research groups throughout the world present their new results. Accordingly this conference has been able to align itself to the current trend in quantum optics and quantum mechanics. The Puebla meeting covered most extensively the following areas: quantum measurements, quantum computing and information theory, trapped atoms and degenerate gases, and the generation and characterization of quantum states of light. The meeting also covered squeeze-like transformations in areas other than quantum optics, such as atomic physics, nuclear physics, statistical physics and relativity, as well as optical devices. There were many new participants at this meeting, particularly from Latin American countries including, of course, Mexico. There were many talks on the subjects traditionally covered in this conference series, including quantum fluctuations, different forms of squeezing, unlike kinds of nonclassical states of light, and distinct representations of the quantum superposition principle, such as even and odd coherent states. The entanglement phenomenon, frequently in the form of the EPR paradox, is responsible for the main advantages of quantum engineering compared with classical methods. Even though entanglement has been known since the early days of quantum mechanics, its properties, such as the most appropriate entanglement measures, are still under current investigation. The phenomena of dissipations and decoherence of the initial pure states are very important because the fast decoherence can destroy all the advantages of quantum processes in teleportation, quantum computing and image processing. Due to this, methods of controlling the decoherence, such as by the use of different kinds of nonlinearities and deformations, are also under study. From the very beginning of quantum mechanics, the uncertainty relations were basic inequalities distinguishing the classical and quantum worlds. Among the theoretical methods for quantum optics and quantum mechanics, this conference covered phase space and group representations, such as the Wigner and probability distribution functions, which provide an alternative approach to the Schr\\"odinger or Heisenberg picture. Different forms of probability representations of quantum states are important tools to be applied in studying various quantum phenomena, such as quantum interference, decoherence and quantum tomography. They have been established also as a very useful tool in all branches of classical optics. From the mathematical point of view, it is well known that the coherent and squeezed states are representations of the Lorentz group. It was noted throughout the conference that another form of the Lorentz group, namely, the 2 x 2 representation of the SL(2,c) group, is becoming more prominent while providing the mathematical basis for the Poincaré sphere, entanglement, qubits and decoherence, as well as classical ray optics traditionally based on 2 x 2 `ABCD' matrices. The contributions of this special issue cover the most recent trends in all areas of quantum optics and the foundations of quantum mechanics.

Zero-phonon-line emission of single molecules for applications in quantum information processing

NASA Astrophysics Data System (ADS)

Kiraz, Alper; Ehrl, M.; Mustecaplioglu, O. E.; Hellerer, T.; Brauchle, C.; Zumbusch, A.

2005-07-01

A single photon source which generates transform limited single photons is highly desirable for applications in quantum optics. Transform limited emission guarantees the indistinguishability of the emitted single photons. This, in turn brings groundbreaking applications in linear optics quantum information processing within an experimental reach. Recently, self-assembled InAs quantum dots and trapped atoms have successfully been demonstrated as such sources for highly indistinguishable single photons. Here, we demonstrate that nearly transform limited zero-phonon-line (ZPL) emission from single molecules can be obtained by using vibronic excitation. Furthermore we report the results of coincidence detection experiments at the output of a Michelson-type interferometer. These experiments reveal Hong-Ou-Mandel correlations as a proof of the indistinguishability of the single photons emitted consecutively from a single molecule. Therefore, single molecules constitute an attractive alternative to single InAs quantum dots and trapped atoms for applications in linear optics quantum information processing. Experiments were performed with a home-built confocal microscope keeping the sample in a superfluid liquid Helium bath at 1.4K. We investigated terrylenediimide (TDI) molecules highly diluted in hexadecane (Shpol'skii matrix). A continuous wave single mode dye laser was used for excitation of vibronic transitions of individual molecules. From the integral fluorescence, the ZPL of single molecules was selected with a spectrally narrow interference filter. The ZPL emission was then sent to a scanning Fabry-Perot interferometer for linewidth measurements or a Michelson-type interferometer for coincidence detection.

Inherent polarization entanglement generated from a monolithic semiconductor chip

PubMed Central

Horn, Rolf T.; Kolenderski, Piotr; Kang, Dongpeng; Abolghasem, Payam; Scarcella, Carmelo; Frera, Adriano Della; Tosi, Alberto; Helt, Lukas G.; Zhukovsky, Sergei V.; Sipe, J. E.; Weihs, Gregor; Helmy, Amr S.; Jennewein, Thomas

2013-01-01

Creating miniature chip scale implementations of optical quantum information protocols is a dream for many in the quantum optics community. This is largely because of the promise of stability and scalability. Here we present a monolithically integratable chip architecture upon which is built a photonic device primitive called a Bragg reflection waveguide (BRW). Implemented in gallium arsenide, we show that, via the process of spontaneous parametric down conversion, the BRW is capable of directly producing polarization entangled photons without additional path difference compensation, spectral filtering or post-selection. After splitting the twin-photons immediately after they emerge from the chip, we perform a variety of correlation tests on the photon pairs and show non-classical behaviour in their polarization. Combined with the BRW's versatile architecture our results signify the BRW design as a serious contender on which to build large scale implementations of optical quantum processing devices. PMID:23896982

Surface ligands affect photoinduced modulation of the quantum dots optical performance

NASA Astrophysics Data System (ADS)

Krivenkov, Victor A.; Samokhvalov, Pavel S.; Linkov, Pavel A.; Solovyeva, Daria O.; Kotkovskii, Gennadii E.; Chistyakov, Alexander A.; Nabiev, Igor

2014-05-01

Changes of optical properties of the solutions of CdSe/ZnS quantum dots (QDs) covered with the trioctylphosphine oxide (TOPO) ligands under the pulsed ultraviolet (UV) laser irradiation are observed. The fluorescence quantum yield (QY) of QDs decreases by more than an order of magnitude when the radiation dose approaches 2 × 10-15 J per particle. This process is accompanied by a blue shift of both fluorescence and the first excitonic absorption peaks. The fluorescence quenching becomes less pronounced when the overall TOPO content in the solution is increased. When ТОРО ligands are replaced with n-hexadecylamine (HDA), QY and spectral properties are not changed at the same irradiation conditions. We assume that the above changes of the optical properties are associated with photooxidation of TOPO ligands by excited QD. Such process is less probable for the HDA ligand due to its different energy structure.

On the passive probing of fiber optic quantum communication channels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korol'kov, A. V., E-mail: sergei.kulik@gmail.co; Katamadze, K. G.; Kulik, S. P.

2010-04-15

Avalanche photodetectors based on InGaAs:P are the most sensitive and only detectors operating in the telecommunication wavelength range 1.30-1.55 {mu}m in the fiber optic quantum cryptography systems that can operate in the single photon count mode. In contrast to the widely used silicon photodetectors for wavelengths up to 1 {mu}m operating in a waiting mode, these detectors always operate in a gated mode. The production of an electron-hole pair in the process of the absorption of a photon and the subsequent appearance of an avalanche of carriers can be accompanied by the inverse processes of the recombination and emission ofmore » photons. Such a backward emission can present a potential serious problem for the stability of fiber optic quantum cryptography systems against passive probing. The results of analyzing the detection of backscattered radiation are reported. The probability of such an emission has been estimated.« less

High-fidelity quantum gates on quantum-dot-confined electron spins in low-Q optical microcavities

NASA Astrophysics Data System (ADS)

Li, Tao; Gao, Jian-Cun; Deng, Fu-Guo; Long, Gui-Lu

2018-04-01

We propose some high-fidelity quantum circuits for quantum computing on electron spins of quantum dots (QD) embedded in low-Q optical microcavities, including the two-qubit controlled-NOT gate and the multiple-target-qubit controlled-NOT gate. The fidelities of both quantum gates can, in principle, be robust to imperfections involved in a practical input-output process of a single photon by converting the infidelity into a heralded error. Furthermore, the influence of two different decay channels is detailed. By decreasing the quality factor of the present microcavity, we can largely increase the efficiencies of these quantum gates while their high fidelities remain unaffected. This proposal also has another advantage regarding its experimental feasibility, in that both quantum gates can work faithfully even when the QD-cavity systems are non-identical, which is of particular importance in current semiconductor QD technology.

50-GHz-spaced comb of high-dimensional frequency-bin entangled photons from an on-chip silicon nitride microresonator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Imany, Poolad; Jaramillo-Villegas, Jose A.; Odele, Ogaga D.

Quantum frequency combs from chip-scale integrated sources are promising candidates for scalable and robust quantum information processing (QIP). However, to use these quantum combs for frequency domain QIP, demonstration of entanglement in the frequency basis, showing that the entangled photons are in a coherent superposition of multiple frequency bins, is required. We present a verification of qubit and qutrit frequency-bin entanglement using an on-chip quantum frequency comb with 40 mode pairs, through a two-photon interference measurement that is based on electro-optic phase modulation. Our demonstrations provide an important contribution in establishing integrated optical microresonators as a source for high-dimensional frequency-binmore » encoded quantum computing, as well as dense quantum key distribution.« less

50-GHz-spaced comb of high-dimensional frequency-bin entangled photons from an on-chip silicon nitride microresonator

DOE PAGES

Imany, Poolad; Jaramillo-Villegas, Jose A.; Odele, Ogaga D.; ...

2018-01-18

Quantum frequency combs from chip-scale integrated sources are promising candidates for scalable and robust quantum information processing (QIP). However, to use these quantum combs for frequency domain QIP, demonstration of entanglement in the frequency basis, showing that the entangled photons are in a coherent superposition of multiple frequency bins, is required. We present a verification of qubit and qutrit frequency-bin entanglement using an on-chip quantum frequency comb with 40 mode pairs, through a two-photon interference measurement that is based on electro-optic phase modulation. Our demonstrations provide an important contribution in establishing integrated optical microresonators as a source for high-dimensional frequency-binmore » encoded quantum computing, as well as dense quantum key distribution.« less

Joining the quantum state of two photons into one

NASA Astrophysics Data System (ADS)

Vitelli, Chiara; Spagnolo, Nicolò; Aparo, Lorenzo; Sciarrino, Fabio; Santamato, Enrico; Marrucci, Lorenzo

2013-07-01

Photons are the ideal carriers of quantum information for communication. Each photon can have a single or multiple qubits encoded in its internal quantum state, as defined by optical degrees of freedom such as polarization, wavelength, transverse modes and so on. However, as photons do not interact, multiplexing and demultiplexing the quantum information across photons has not been possible hitherto. Here, we introduce and demonstrate experimentally a physical process, named `quantum joining', in which the two-dimensional quantum states (qubits) of two input photons are combined into a single output photon, within a four-dimensional Hilbert space. The inverse process is also proposed, in which the four-dimensional quantum state of a single photon is split into two photons, each carrying a qubit. Both processes can be iterated, and hence provide a flexible quantum interconnect to bridge multiparticle protocols of quantum information with multidegree-of-freedom ones, with possible applications in future quantum networking.

Broadband photon pair generation in green fluorescent proteins through spontaneous four-wave mixing

PubMed Central

Shi, Siyuan; Thomas, Abu; Corzo, Neil V.; Kumar, Prem; Huang, Yuping; Lee, Kim Fook

2016-01-01

Recent studies in quantum biology suggest that quantum mechanics help us to explore quantum processes in biological system. Here, we demonstrate generation of photon pairs through spontaneous four-wave mixing process in naturally occurring fluorescent proteins. We develop a general empirical method for analyzing the relative strength of nonlinear optical interaction processes in five different organic fluorophores. Our results indicate that the generation of photon pairs in green fluorescent proteins is subject to less background noises than in other fluorophores, leading to a coincidence-to-accidental ratio ~145. As such proteins can be genetically engineered and fused to many biological cells, our experiment enables a new platform for quantum information processing in a biological environment such as biomimetic quantum networks and quantum sensors. PMID:27076032

Influence of Fano interference and incoherent processes on optical bistability in a four-level quantum dot nanostructure

NASA Astrophysics Data System (ADS)

Seyyed, Hossein Asadpour; G, Solookinejad; M, Panahi; E Ahmadi, Sangachin

2016-03-01

Role of Fano interference and incoherent pumping field on optical bistability in a four-level designed InGaN/GaN quantum dot nanostructure embedded in a unidirectional ring cavity are analyzed. It is found that intensity threshold of optical bistability can be manipulated by Fano interference. It is shown that incoherent pumping fields make the threshold of optical bistability behave differently by Fano interference. Moreover, in the presence of Fano interference the medium becomes phase-dependent. Therefore, the relative phase of applied fields can affect the behaviors of optical bistability and intensity threshold can be controlled easily.

Quantum Noise Reduction with Pulsed Light in Optical Fibers.

NASA Astrophysics Data System (ADS)

Bergman, Keren

Optical fibers offer considerable advantages over bulk nonlinear media for the generation of squeezed states. This thesis reports on experimental investigations of reducing quantum noise by means of squeezing in nonlinear fiber optic interferometers. Fibers have low insertion loss which allows for long interaction lengths. High field intensities are easily achieved in the small cores of single mode fibers. Additionally, the nonlinear process employed is self phase modulation or the Kerr effect, whose broad band nature requires no phase matching and can be exploited with ultra-short pulses of high peak intensity. All these advantageous features of fibers result in easily obtained large nonlinear phase shifts and subsequently large squeezing parameters. By the self phase modulation process a correlation is produced between the phase and amplitude fluctuations of the optical field. The attenuated or squeezed quadrature has a lower noise level than the initial level associated with the coherent state field before propagation. The resulting reduced quantum noise quadrature can be utilized to improve the sensitivity of a phase measuring instrument such as an interferometer. Because the Kerr nonlinearity is a degenerate self pumping process, the squeezed noise is at the same frequency as the pump field. Classical pump noise can therefore interfere with the desired measurement of the quantum noise reduction. The most severe noise process is the phase noise caused by thermally induced index modulation of the fiber. This noise termed Guided Acoustic Wave Brillouin Scattering, or GAWBS, by previous researchers is studied and analyzed. Experiments performed to overcome GAWBS successfully with several schemes are described. An experimental demonstration of an interferometric measurement with better sensitivity than the standard quantum limit is described. The results lead to new understandings into the limitations of quantum noise reduction that can be achieved in the laboratory. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.).

Integrated source of tunable nonmaximally mode-entangled photons in a domain-engineered lithium niobate waveguide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ming, Yang; Wu, Zi-jian; Xu, Fei, E-mail: feixu@nju.edu.cn

The nonmaximally entangled state is a special kind of entangled state, which has important applications in quantum information processing. It has been generated in quantum circuits based on bulk optical elements. However, corresponding schemes in integrated quantum circuits have been rarely considered. In this Letter, we propose an effective solution for this problem. An electro-optically tunable nonmaximally mode-entangled photon state is generated in an on-chip domain-engineered lithium niobate (LN) waveguide. Spontaneous parametric down-conversion and electro-optic interaction are effectively combined through suitable domain design to transform the entangled state into our desired formation. Moreover, this is a flexible approach to entanglementmore » architectures. Other kinds of reconfigurable entanglements are also achievable through this method. LN provides a very promising platform for future quantum circuit integration.« less

Generation of Antibunched Light by Excited Molecules in a Microcavity Trap

NASA Technical Reports Server (NTRS)

DeMartini, F.; DiGiuseppe, G.; Marrocco, M.

1996-01-01

The active microcavity is adopted as an efficient source of non-classical light. By this device, excited by a mode-locked laser at a rate of 100 MHz, single-photons are generated over a single field mode with a nonclassical sub-poissonian distribution. The process of adiabatic recycling within a multi-step Franck-Condon molecular optical-pumping mechanism, characterized in our case by a quantum efficiency very close to one, implies a pump self-regularization process leading to a striking n-squeezing effect. By a replication of the basic single-atom excitation process a beam of quantum photon (Fock states) can be created. The new process represents a significant advance in the modern fields of basic quantum-mechanical investigation, quantum communication and quantum cryptography.

Towards scalable quantum communication and computation: Novel approaches and realizations

NASA Astrophysics Data System (ADS)

Jiang, Liang

Quantum information science involves exploration of fundamental laws of quantum mechanics for information processing tasks. This thesis presents several new approaches towards scalable quantum information processing. First, we consider a hybrid approach to scalable quantum computation, based on an optically connected network of few-qubit quantum registers. Specifically, we develop a novel scheme for scalable quantum computation that is robust against various imperfections. To justify that nitrogen-vacancy (NV) color centers in diamond can be a promising realization of the few-qubit quantum register, we show how to isolate a few proximal nuclear spins from the rest of the environment and use them for the quantum register. We also demonstrate experimentally that the nuclear spin coherence is only weakly perturbed under optical illumination, which allows us to implement quantum logical operations that use the nuclear spins to assist the repetitive-readout of the electronic spin. Using this technique, we demonstrate more than two-fold improvement in signal-to-noise ratio. Apart from direct application to enhance the sensitivity of the NV-based nano-magnetometer, this experiment represents an important step towards the realization of robust quantum information processors using electronic and nuclear spin qubits. We then study realizations of quantum repeaters for long distance quantum communication. Specifically, we develop an efficient scheme for quantum repeaters based on atomic ensembles. We use dynamic programming to optimize various quantum repeater protocols. In addition, we propose a new protocol of quantum repeater with encoding, which efficiently uses local resources (about 100 qubits) to identify and correct errors, to achieve fast one-way quantum communication over long distances. Finally, we explore quantum systems with topological order. Such systems can exhibit remarkable phenomena such as quasiparticles with anyonic statistics and have been proposed as candidates for naturally error-free quantum computation. We propose a scheme to unambiguously detect the anyonic statistics in spin lattice realizations using ultra-cold atoms in an optical lattice. We show how to reliably read and write topologically protected quantum memory using an atomic or photonic qubit.

Towards zero-threshold optical gain using charged semiconductor quantum dots

DOE PAGES

Wu, Kaifeng; Park, Young -Shin; Lim, Jaehoon; ...

2017-10-16

Colloidal semiconductor quantum dots are attractive materials for the realization of solution-processable lasers. However, their applications as optical-gain media are complicated by a non-unity degeneracy of band-edge states, because of which multiexcitons are required to achieve the lasing regime. This increases the lasing thresholds and leads to very short optical gain lifetimes limited by nonradiative Auger recombination. Here, we show that these problems can be at least partially resolved by employing not neutral but negatively charged quantum dots. By applying photodoping to specially engineered quantum dots with impeded Auger decay, we demonstrate a considerable reduction of the optical gain thresholdmore » due to suppression of ground-state absorption by pre-existing carriers. Moreover, by injecting approximately one electron per dot on average, we achieve a more than twofold reduction in the amplified spontaneous emission threshold, bringing it to the sub-single-exciton level. Furthermore, these measurements indicate the feasibility of ‘zero-threshold’ gain achievable by completely blocking the band-edge state with two electrons.« less

Towards zero-threshold optical gain using charged semiconductor quantum dots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Kaifeng; Park, Young -Shin; Lim, Jaehoon

Colloidal semiconductor quantum dots are attractive materials for the realization of solution-processable lasers. However, their applications as optical-gain media are complicated by a non-unity degeneracy of band-edge states, because of which multiexcitons are required to achieve the lasing regime. This increases the lasing thresholds and leads to very short optical gain lifetimes limited by nonradiative Auger recombination. Here, we show that these problems can be at least partially resolved by employing not neutral but negatively charged quantum dots. By applying photodoping to specially engineered quantum dots with impeded Auger decay, we demonstrate a considerable reduction of the optical gain thresholdmore » due to suppression of ground-state absorption by pre-existing carriers. Moreover, by injecting approximately one electron per dot on average, we achieve a more than twofold reduction in the amplified spontaneous emission threshold, bringing it to the sub-single-exciton level. Furthermore, these measurements indicate the feasibility of ‘zero-threshold’ gain achievable by completely blocking the band-edge state with two electrons.« less

Quantum information processing with a travelling wave of light

NASA Astrophysics Data System (ADS)

Serikawa, Takahiro; Shiozawa, Yu; Ogawa, Hisashi; Takanashi, Naoto; Takeda, Shuntaro; Yoshikawa, Jun-ichi; Furusawa, Akira

2018-02-01

We exploit quantum information processing on a traveling wave of light, expecting emancipation from thermal noise, easy coupling to fiber communication, and potentially high operation speed. Although optical memories are technically challenging, we have an alternative approach to apply multi-step operations on traveling light, that is, continuous-variable one-way computation. So far our achievement includes generation of a one-million-mode entangled chain in time-domain, mode engineering of nonlinear resource states, and real-time nonlinear feedforward. Although they are implemented with free space optics, we are also investigating photonic integration and performed quantum teleportation with a passive liner waveguide chip as a demonstration of entangling, measurement, and feedforward. We also suggest a loop-based architecture as another model of continuous-variable computing.

Two-Hierarchy Entanglement Swapping for a Linear Optical Quantum Repeater

NASA Astrophysics Data System (ADS)

Xu, Ping; Yong, Hai-Lin; Chen, Luo-Kan; Liu, Chang; Xiang, Tong; Yao, Xing-Can; Lu, He; Li, Zheng-Da; Liu, Nai-Le; Li, Li; Yang, Tao; Peng, Cheng-Zhi; Zhao, Bo; Chen, Yu-Ao; Pan, Jian-Wei

2017-10-01

Quantum repeaters play a significant role in achieving long-distance quantum communication. In the past decades, tremendous effort has been devoted towards constructing a quantum repeater. As one of the crucial elements, entanglement has been created in different memory systems via entanglement swapping. The realization of j -hierarchy entanglement swapping, i.e., connecting quantum memory and further extending the communication distance, is important for implementing a practical quantum repeater. Here, we report the first demonstration of a fault-tolerant two-hierarchy entanglement swapping with linear optics using parametric down-conversion sources. In the experiment, the dominant or most probable noise terms in the one-hierarchy entanglement swapping, which is on the same order of magnitude as the desired state and prevents further entanglement connections, are automatically washed out by a proper design of the detection setting, and the communication distance can be extended. Given suitable quantum memory, our techniques can be directly applied to implementing an atomic ensemble based quantum repeater, and are of significant importance in the scalable quantum information processing.

Analysis of quantum information processors using quantum metrology

NASA Astrophysics Data System (ADS)

Kandula, Mark J.; Kok, Pieter

2018-06-01

Physical implementations of quantum information processing devices are generally not unique, and we are faced with the problem of choosing the best implementation. Here, we consider the sensitivity of quantum devices to variations in their different components. To measure this, we adopt a quantum metrological approach and find that the sensitivity of a device to variations in a component has a particularly simple general form. We use the concept of cost functions to establish a general practical criterion to decide between two different physical implementations of the same quantum device consisting of a variety of components. We give two practical examples of sensitivities of quantum devices to variations in beam splitter transmittivities: the Knill-Laflamme-Milburn (KLM) and reverse nonlinear sign gates for linear optical quantum computing with photonic qubits, and the enhanced optical Bell detectors by Grice and Ewert and van Loock. We briefly compare the sensitivity to the diamond distance and find that the latter is less suited for studying the behavior of components embedded within the larger quantum device.

Two-Hierarchy Entanglement Swapping for a Linear Optical Quantum Repeater.

PubMed

Xu, Ping; Yong, Hai-Lin; Chen, Luo-Kan; Liu, Chang; Xiang, Tong; Yao, Xing-Can; Lu, He; Li, Zheng-Da; Liu, Nai-Le; Li, Li; Yang, Tao; Peng, Cheng-Zhi; Zhao, Bo; Chen, Yu-Ao; Pan, Jian-Wei

2017-10-27

Quantum repeaters play a significant role in achieving long-distance quantum communication. In the past decades, tremendous effort has been devoted towards constructing a quantum repeater. As one of the crucial elements, entanglement has been created in different memory systems via entanglement swapping. The realization of j-hierarchy entanglement swapping, i.e., connecting quantum memory and further extending the communication distance, is important for implementing a practical quantum repeater. Here, we report the first demonstration of a fault-tolerant two-hierarchy entanglement swapping with linear optics using parametric down-conversion sources. In the experiment, the dominant or most probable noise terms in the one-hierarchy entanglement swapping, which is on the same order of magnitude as the desired state and prevents further entanglement connections, are automatically washed out by a proper design of the detection setting, and the communication distance can be extended. Given suitable quantum memory, our techniques can be directly applied to implementing an atomic ensemble based quantum repeater, and are of significant importance in the scalable quantum information processing.

Quantum state conversion in opto-electro-mechanical systems via shortcut to adiabaticity

NASA Astrophysics Data System (ADS)

Zhou, Xiao; Liu, Bao-Jie; Shao, L.-B.; Zhang, Xin-Ding; Xue, Zheng-Yuan

2017-09-01

Adiabatic processes have found many important applications in modern physics, the distinct merit of which is that accurate control over process timing is not required. However, such processes are slow, which limits their application in quantum computation, due to the limited coherent times of typical quantum systems. Here, we propose a scheme to implement quantum state conversion in opto-electro-mechanical systems via a shortcut to adiabaticity, where the process can be greatly speeded up while precise timing control is still not necessary. In our scheme, by modifying only the coupling strength, we can achieve fast quantum state conversion with high fidelity, where the adiabatic condition does not need to be met. In addition, the population of the unwanted intermediate state can be further suppressed. Therefore, our protocol presents an important step towards practical state conversion between optical and microwave photons, and thus may find many important applications in hybrid quantum information processing.

Long-Distance Single Photon Transmission from a Trapped Ion via Quantum Frequency Conversion

NASA Astrophysics Data System (ADS)

Walker, Thomas; Miyanishi, Koichiro; Ikuta, Rikizo; Takahashi, Hiroki; Vartabi Kashanian, Samir; Tsujimoto, Yoshiaki; Hayasaka, Kazuhiro; Yamamoto, Takashi; Imoto, Nobuyuki; Keller, Matthias

2018-05-01

Trapped atomic ions are ideal single photon emitters with long-lived internal states which can be entangled with emitted photons. Coupling the ion to an optical cavity enables the efficient emission of single photons into a single spatial mode and grants control over their temporal shape. These features are key for quantum information processing and quantum communication. However, the photons emitted by these systems are unsuitable for long-distance transmission due to their wavelengths. Here we report the transmission of single photons from a single 40Ca+ ion coupled to an optical cavity over a 10 km optical fiber via frequency conversion from 866 nm to the telecom C band at 1530 nm. We observe nonclassical photon statistics of the direct cavity emission, the converted photons, and the 10 km transmitted photons, as well as the preservation of the photons' temporal shape throughout. This telecommunication-ready system can be a key component for long-distance quantum communication as well as future cloud quantum computation.

Schemes generating entangled states and entanglement swapping between photons and three-level atoms inside optical cavities for quantum communication

NASA Astrophysics Data System (ADS)

Heo, Jino; Kang, Min-Sung; Hong, Chang-Ho; Yang, Hyeon; Choi, Seong-Gon

2017-01-01

We propose quantum information processing schemes based on cavity quantum electrodynamics (QED) for quantum communication. First, to generate entangled states (Bell and Greenberger-Horne-Zeilinger [GHZ] states) between flying photons and three-level atoms inside optical cavities, we utilize a controlled phase flip (CPF) gate that can be implemented via cavity QED). Subsequently, we present an entanglement swapping scheme that can be realized using single-qubit measurements and CPF gates via optical cavities. These schemes can be directly applied to construct an entanglement channel for a communication system between two users. Consequently, it is possible for the trust center, having quantum nodes, to accomplish the linked channel (entanglement channel) between the two separate long-distance users via the distribution of Bell states and entanglement swapping. Furthermore, in our schemes, the main physical component is the CPF gate between the photons and the three-level atoms in cavity QED, which is feasible in practice. Thus, our schemes can be experimentally realized with current technology.

Demonstration of a quantum controlled-NOT gate in the telecommunications band.

PubMed

Chen, Jun; Altepeter, Joseph B; Medic, Milja; Lee, Kim Fook; Gokden, Burc; Hadfield, Robert H; Nam, Sae Woo; Kumar, Prem

2008-04-04

We present the first quantum controlled-not (cnot) gate realized using a fiber-based indistinguishable photon-pair source in the 1.55 microm telecommunications band. Using this free-space cnot gate, all four Bell states are produced and fully characterized by performing quantum-state tomography, demonstrating the gate's unambiguous entangling capability and high fidelity. Telecom-band operation makes this cnot gate particularly suitable for quantum-information-processing tasks that are at the interface of quantum communication and linear optical quantum computing.

Experimental simulation of monogamy relation between contextuality and nonlocality in classical light.

PubMed

Li, Tao; Zhang, Xiong; Zeng, Qiang; Wang, Bo; Zhang, Xiangdong

2018-04-30

The Clauser-Horne-Shimony-Holt (CHSH) inequality and the Klyachko-Can-Binicioglu-Shumovski (KCBS) inequality present a tradeoff on the no-disturbance (ND) principle. Recently, the fundamental monogamy relation between contextuality and nonlocality in quantum theory has been demonstrated experimentally. Here we show that such a relation and tradeoff can also be simulated in classical optical systems. Using polarization, path and orbital angular momentum of the classical optical beam, in classical optical experiment we have observed the stringent monogamy relation between the two inequalities by implementing the projection measurement. Our results show the application prospect of the concepts developed recently in quantum information science to classical optical system and optical information processing.

Enhancement of optical Kerr effect in quantum-cascade lasers with multiple resonance levels.

PubMed

Bai, Jing; Citrin, D S

2008-08-18

In this paper, we investigated the optical Kerr lensing effect in quantum-cascade lasers with multiple resonance levels. The Kerr refractive index n2 is obtained through the third-order susceptibility at the fundamental frequency chi(3)( omega; omega, omega,-omega). Resonant two-photon processes are found to have almost equal contributions to chi(3)( omega; omega, omega,-omega) as the single-photon processes, which result in the predicted enhancement of the positive nonlinear (Kerr) refractive index, and thus may enhance mode-locking of quantum-cascade lasers. Moreover, we also demonstrate an isospectral optimization strategy for further improving n2 through the band-structure design, in order to boost the multimode performance of quantum-cascade lasers. Simulation results show that the optimized stepwise multiple-quantum-well structure has n2 approximately 10-8 cm2/W, a twofold enhancement over the original flat quantum-well structure. This leads to a refractive-index change (delta)n of about 0.01, which is at the upper bound of those reported for typical Kerr medium. This stronger Kerr refractive index may be important for quantum-cascade lasers ultimately to demonstrate self-mode-locking.

Experimental entanglement of 25 individually accessible atomic quantum interfaces.

PubMed

Pu, Yunfei; Wu, Yukai; Jiang, Nan; Chang, Wei; Li, Chang; Zhang, Sheng; Duan, Luming

2018-04-01

A quantum interface links the stationary qubits in a quantum memory with flying photonic qubits in optical transmission channels and constitutes a critical element for the future quantum internet. Entanglement of quantum interfaces is an important step for the realization of quantum networks. Through heralded detection of photon interference, we generate multipartite entanglement between 25 (or 9) individually addressable quantum interfaces in a multiplexed atomic quantum memory array and confirm genuine 22-partite (or 9-partite) entanglement. This experimental entanglement of a record-high number of individually addressable quantum interfaces makes an important step toward the realization of quantum networks, long-distance quantum communication, and multipartite quantum information processing.

Semiconductor Quantum Dots for Biomedicial Applications

PubMed Central

Shao, Lijia; Gao, Yanfang; Yan, Feng

2011-01-01

Semiconductor quantum dots (QDs) are nanometre-scale crystals, which have unique photophysical properties, such as size-dependent optical properties, high fluorescence quantum yields, and excellent stability against photobleaching. These properties enable QDs as the promising optical labels for the biological applications, such as multiplexed analysis of immunocomplexes or DNA hybridization processes, cell sorting and tracing, in vivo imaging and diagnostics in biomedicine. Meanwhile, QDs can be used as labels for the electrochemical detection of DNA or proteins. This article reviews the synthesis and toxicity of QDs and their optical and electrochemical bioanalytical applications. Especially the application of QDs in biomedicine such as delivering, cell targeting and imaging for cancer research, and in vivo photodynamic therapy (PDT) of cancer are briefly discussed. PMID:22247690

On-chip generation of high-dimensional entangled quantum states and their coherent control

NASA Astrophysics Data System (ADS)

Kues, Michael; Reimer, Christian; Roztocki, Piotr; Cortés, Luis Romero; Sciara, Stefania; Wetzel, Benjamin; Zhang, Yanbing; Cino, Alfonso; Chu, Sai T.; Little, Brent E.; Moss, David J.; Caspani, Lucia; Azaña, José; Morandotti, Roberto

2017-06-01

Optical quantum states based on entangled photons are essential for solving questions in fundamental physics and are at the heart of quantum information science. Specifically, the realization of high-dimensional states (D-level quantum systems, that is, qudits, with D > 2) and their control are necessary for fundamental investigations of quantum mechanics, for increasing the sensitivity of quantum imaging schemes, for improving the robustness and key rate of quantum communication protocols, for enabling a richer variety of quantum simulations, and for achieving more efficient and error-tolerant quantum computation. Integrated photonics has recently become a leading platform for the compact, cost-efficient, and stable generation and processing of non-classical optical states. However, so far, integrated entangled quantum sources have been limited to qubits (D = 2). Here we demonstrate on-chip generation of entangled qudit states, where the photons are created in a coherent superposition of multiple high-purity frequency modes. In particular, we confirm the realization of a quantum system with at least one hundred dimensions, formed by two entangled qudits with D = 10. Furthermore, using state-of-the-art, yet off-the-shelf telecommunications components, we introduce a coherent manipulation platform with which to control frequency-entangled states, capable of performing deterministic high-dimensional gate operations. We validate this platform by measuring Bell inequality violations and performing quantum state tomography. Our work enables the generation and processing of high-dimensional quantum states in a single spatial mode.

On-chip generation of high-dimensional entangled quantum states and their coherent control.

PubMed

Kues, Michael; Reimer, Christian; Roztocki, Piotr; Cortés, Luis Romero; Sciara, Stefania; Wetzel, Benjamin; Zhang, Yanbing; Cino, Alfonso; Chu, Sai T; Little, Brent E; Moss, David J; Caspani, Lucia; Azaña, José; Morandotti, Roberto

2017-06-28

Optical quantum states based on entangled photons are essential for solving questions in fundamental physics and are at the heart of quantum information science. Specifically, the realization of high-dimensional states (D-level quantum systems, that is, qudits, with D > 2) and their control are necessary for fundamental investigations of quantum mechanics, for increasing the sensitivity of quantum imaging schemes, for improving the robustness and key rate of quantum communication protocols, for enabling a richer variety of quantum simulations, and for achieving more efficient and error-tolerant quantum computation. Integrated photonics has recently become a leading platform for the compact, cost-efficient, and stable generation and processing of non-classical optical states. However, so far, integrated entangled quantum sources have been limited to qubits (D = 2). Here we demonstrate on-chip generation of entangled qudit states, where the photons are created in a coherent superposition of multiple high-purity frequency modes. In particular, we confirm the realization of a quantum system with at least one hundred dimensions, formed by two entangled qudits with D = 10. Furthermore, using state-of-the-art, yet off-the-shelf telecommunications components, we introduce a coherent manipulation platform with which to control frequency-entangled states, capable of performing deterministic high-dimensional gate operations. We validate this platform by measuring Bell inequality violations and performing quantum state tomography. Our work enables the generation and processing of high-dimensional quantum states in a single spatial mode.

Integration of micro-/nano-/quantum-scale photonic devices: scientific and technological considerations

NASA Astrophysics Data System (ADS)

Lee, El-Hang; Lee, Seung-Gol; O, Beom Hoan; Park, Se Geun

2004-08-01

Scientific and technological issues and considerations regarding the integration of miniaturized microphotonic devices, circuits and systems in micron, submicron, and quantum scale, are presented. First, we examine the issues regarding the miniaturization of photonic devices including the size effect, proximity effect, energy confinement effect, microcavity effect, optical and quantum interference effect, high field effect, nonlinear effect, noise effect, quantum optical effect, and chaotic effect. Secondly, we examine the issues regarding the interconnection including the optical alignment, minimizing the interconnection losses, and maintaining optical modes. Thirdly, we address the issues regarding the two-dimensional or three-dimensional integration either in a hybrid format or in a monolithic format between active devices and passive devices of varying functions. We find that the concept of optical printed circuit board (O-PCB) that we propose is highly attractive as a platform for micro/nano/quantum-scale photonic integration. We examine the technological issues to be addressed in the process of fabrication, characterization, and packaging for actual implementation of the miniaturization, interconnection and integration. Devices that we have used for our study include: mode conversion schemes, micro-ring and micro-racetrack resonator devices, multimode interference devices, lasers, vertical cavity surface emitting microlasers, and their arrays. Future prospects are also discussed.

Role of magnetic and diamagnetic interactions in molecular optics and scattering

NASA Astrophysics Data System (ADS)

Forbes, Kayn A.

2018-05-01

This paper aims to explicitly clarify the role and interpretation of diamagnetic interactions between molecules and light in quantum electrodynamics. In contrast to their electric and magnetic counterparts, the diamagnetic couplings between light and matter have received relatively little interest in the field of molecular optics. This intriguing disregard of an interaction term is puzzling. The diamagnetic couplings possess unique physical properties that warrant their inclusion in any multiphoton process, and the lack of gauge invariance for paramagnetic and diamagnetic susceptibilities necessitates their inclusion. Their role and importance within nonrelativistic molecular quantum electrodynamics in the Coulomb gauge is illuminated, and it is highlighted how for any multiphoton process their inclusion should be implicit. As an indicative example of the theory presented, the diamagnetic contributions to both forward and nonforward Rayleigh scattering are derived and put into context alongside the electric and magnetic molecular responses. The work represents clarification of diamagnetic couplings in molecular quantum electrodynamics, which subsequently should proffer the study of diamagnetic interactions in molecular optics due to their unique physical attributes and necessary inclusion in multiphoton processes.

Quantum optics. All-optical routing of single photons by a one-atom switch controlled by a single photon.

PubMed

Shomroni, Itay; Rosenblum, Serge; Lovsky, Yulia; Bechler, Orel; Guendelman, Gabriel; Dayan, Barak

2014-08-22

The prospect of quantum networks, in which quantum information is carried by single photons in photonic circuits, has long been the driving force behind the effort to achieve all-optical routing of single photons. We realized a single-photon-activated switch capable of routing a photon from any of its two inputs to any of its two outputs. Our device is based on a single atom coupled to a fiber-coupled, chip-based microresonator. A single reflected control photon toggles the switch from high reflection (R ~ 65%) to high transmission (T ~ 90%), with an average of ~1.5 control photons per switching event (~3, including linear losses). No additional control fields are required. The control and target photons are both in-fiber and practically identical, making this scheme compatible with scalable architectures for quantum information processing. Copyright © 2014, American Association for the Advancement of Science.

Practical photon number detection with electric field-modulated silicon avalanche photodiodes.

PubMed

Thomas, O; Yuan, Z L; Shields, A J

2012-01-24

Low-noise single-photon detection is a prerequisite for quantum information processing using photonic qubits. In particular, detectors that are able to accurately resolve the number of photons in an incident light pulse will find application in functions such as quantum teleportation and linear optics quantum computing. More generally, such a detector will allow the advantages of quantum light detection to be extended to stronger optical signals, permitting optical measurements limited only by fluctuations in the photon number of the source. Here we demonstrate a practical high-speed device, which allows the signals arising from multiple photon-induced avalanches to be precisely discriminated. We use a type of silicon avalanche photodiode in which the lateral electric field profile is strongly modulated in order to realize a spatially multiplexed detector. Clearly discerned multiphoton signals are obtained by applying sub-nanosecond voltage gates in order to restrict the detector current.

Nonequilibrium Langevin approach to quantum optics in semiconductor microcavities

NASA Astrophysics Data System (ADS)

Portolan, S.; di Stefano, O.; Savasta, S.; Rossi, F.; Girlanda, R.

2008-01-01

Recently, the possibility of generating nonclassical polariton states by means of parametric scattering has been demonstrated. Excitonic polaritons propagate in a complex interacting environment and contain real electronic excitations subject to scattering events and noise affecting quantum coherence and entanglement. Here, we present a general theoretical framework for the realistic investigation of polariton quantum correlations in the presence of coherent and incoherent interaction processes. The proposed theoretical approach is based on the nonequilibrium quantum Langevin approach for open systems applied to interacting-electron complexes described within the dynamics controlled truncation scheme. It provides an easy recipe to calculate multitime correlation functions which are key quantities in quantum optics. As a first application, we analyze the buildup of polariton parametric emission in semiconductor microcavities including the influence of noise originating from phonon-induced scattering.

Coherent control of diamond defects for quantum information science and quantum sensing

NASA Astrophysics Data System (ADS)

Maurer, Peter

Quantum mechanics, arguably one of the greatest achievements of modern physics, has not only fundamentally changed our understanding of nature but is also taking an ever increasing role in engineering. Today, the control of quantum systems has already had a far-reaching impact on time and frequency metrology. By gaining further control over a large variety of different quantum systems, many potential applications are emerging. Those applications range from the development of quantum sensors and new quantum metrological approaches to the realization of quantum information processors and quantum networks. Unfortunately most quantum systems are very fragile objects that require tremendous experimental effort to avoid dephasing. Being able to control the interaction between a quantum system with its local environment embodies therefore an important aspect for application and hence is at the focus of this thesis. Nitrogen Vacancy (NV) color centers in diamond have recently attracted attention as a room temperature solid state spin system that expresses long coherence times. The electronic spin associated with NV centers can be efficiently manipulated, initialized and readout using microwave and optical techniques. Inspired by these extraordinary properties, much effort has been dedicated to use NV centers as a building block for scalable room temperature quantum information processing and quantum communication as well as a quantum sensing. In the first part of this thesis we demonstrate that by decoupling the spin from the local environment the coherence time of a NV quantum register can be extended by three order of magnitudes. Employing a novel dissipative mechanism in combination with dynamical decoupling, memory times exceeding one second are observed. The second part shows that, based on quantum control, NV centers in nano-diamonds provide a nanoscale temperature sensor with unprecedented accuracy enabling local temperature measurements in living biological cells. This opens the door for the engineering of nano-scaled chemical reactions to the study of temperature dependent biological processes. Finally, a novel technique is introduced that facilitates optical spin detection with nanoscale resolution based on an optical far-field technique; by combining this with a 'quantum Zeno' like effect coherent manipulation of nominally identical spins at a nanoscale is achieved.

Acoustically regulated optical emission dynamics from quantum dot-like emission centers in GaN/InGaN nanowire heterostructures

NASA Astrophysics Data System (ADS)

Lazić, S.; Chernysheva, E.; Hernández-Mínguez, A.; Santos, P. V.; van der Meulen, H. P.

2018-03-01

We report on experimental studies of the effects induced by surface acoustic waves on the optical emission dynamics of GaN/InGaN nanowire quantum dots. We employ stroboscopic optical excitation with either time-integrated or time-resolved photoluminescence detection. In the absence of the acoustic wave, the emission spectra reveal signatures originated from the recombination of neutral exciton and biexciton confined in the probed nanowire quantum dot. When the nanowire is perturbed by the propagating acoustic wave, the embedded quantum dot is periodically strained and its excitonic transitions are modulated by the acousto-mechanical coupling. Depending on the recombination lifetime of the involved optical transitions, we can resolve acoustically driven radiative processes over time scales defined by the acoustic cycle. At high acoustic amplitudes, we also observe distortions in the transmitted acoustic waveform, which are reflected in the time-dependent spectral response of our sensor quantum dot. In addition, the correlated intensity oscillations observed during temporal decay of the exciton and biexciton emission suggest an effect of the acoustic piezoelectric fields on the quantum dot charge population. The present results are relevant for the dynamic spectral and temporal control of photon emission in III-nitride semiconductor heterostructures.

From Three-Photon Greenberger-Horne-Zeilinger States to Ballistic Universal Quantum Computation.

PubMed

Gimeno-Segovia, Mercedes; Shadbolt, Pete; Browne, Dan E; Rudolph, Terry

2015-07-10

Single photons, manipulated using integrated linear optics, constitute a promising platform for universal quantum computation. A series of increasingly efficient proposals have shown linear-optical quantum computing to be formally scalable. However, existing schemes typically require extensive adaptive switching, which is experimentally challenging and noisy, thousands of photon sources per renormalized qubit, and/or large quantum memories for repeat-until-success strategies. Our work overcomes all these problems. We present a scheme to construct a cluster state universal for quantum computation, which uses no adaptive switching, no large memories, and which is at least an order of magnitude more resource efficient than previous passive schemes. Unlike previous proposals, it is constructed entirely from loss-detecting gates and offers a robustness to photon loss. Even without the use of an active loss-tolerant encoding, our scheme naturally tolerates a total loss rate ∼1.6% in the photons detected in the gates. This scheme uses only 3 Greenberger-Horne-Zeilinger states as a resource, together with a passive linear-optical network. We fully describe and model the iterative process of cluster generation, including photon loss and gate failure. This demonstrates that building a linear-optical quantum computer needs to be less challenging than previously thought.

Comparison of the Optical Properties of Graphene and Alkyl-terminated Si and Ge Quantum Dots.

PubMed

de Weerd, Chris; Shin, Yonghun; Marino, Emanuele; Kim, Joosung; Lee, Hyoyoung; Saeed, Saba; Gregorkiewicz, Tom

2017-10-31

Semiconductor quantum dots are widely investigated due to their size dependent energy structure. In particular, colloidal quantum dots represent a promising nanomaterial for optoelectronic devices, such as photodetectors and solar cells, but also luminescent markers for biotechnology, among other applications. Ideal materials for these applications should feature efficient radiative recombination and absorption transitions, altogether with spectral tunability over a wide range. Group IV semiconductor quantum dots can fulfill these requirements and serve as an alternative to the commonly used direct bandgap materials containing toxic and/or rare elements. Here, we present optical properties of butyl-terminated Si and Ge quantum dots and compare them to those of graphene quantum dots, finding them remarkably similar. We investigate their time-resolved photoluminescence emission as well as the photoluminescence excitation and linear absorption spectra. We contemplate that their emission characteristics indicate a (semi-) resonant activation of the emitting channel; the photoluminescence excitation shows characteristics similar to those of a molecule. The optical density is consistent with band-to-band absorption processes originating from core-related states. Hence, these observations strongly indicate a different microscopic origin for absorption and radiative recombination in the three investigated quantum dot systems.

Achieving nonlinear optical modulation via four-wave mixing in a four-level atomic system

NASA Astrophysics Data System (ADS)

Li, Hai-Chao; Ge, Guo-Qin; Zubairy, M. Suhail

2018-05-01

We propose an accessible scheme for implementing tunable nonlinear optical amplification and attenuation via a synergetic mechanism of four-wave mixing (FWM) and optical interference in a four-level ladder-type atomic system. By constructing a cyclic atom-field interaction, we show that two reverse FWM processes can coexist via optical transitions in different branches. In the suitable input-field conditions, strong interference effects between the input fields and the generated FWM fields can be induced and result in large amplification and deep attenuation of the output fields. Moreover, such an optical modulation from enhancement to suppression can be controlled by tuning the relative phase. The quantum system can be served as a switchable optical modulator with potential applications in quantum nonlinear optics.

Quantum memory Quantum memory

NASA Astrophysics Data System (ADS)

Le Gouët, Jean-Louis; Moiseev, Sergey

2012-06-01

Interaction of quantum radiation with multi-particle ensembles has sparked off intense research efforts during the past decade. Emblematic of this field is the quantum memory scheme, where a quantum state of light is mapped onto an ensemble of atoms and then recovered in its original shape. While opening new access to the basics of light-atom interaction, quantum memory also appears as a key element for information processing applications, such as linear optics quantum computation and long-distance quantum communication via quantum repeaters. Not surprisingly, it is far from trivial to practically recover a stored quantum state of light and, although impressive progress has already been accomplished, researchers are still struggling to reach this ambitious objective. This special issue provides an account of the state-of-the-art in a fast-moving research area that makes physicists, engineers and chemists work together at the forefront of their discipline, involving quantum fields and atoms in different media, magnetic resonance techniques and material science. Various strategies have been considered to store and retrieve quantum light. The explored designs belong to three main—while still overlapping—classes. In architectures derived from photon echo, information is mapped over the spectral components of inhomogeneously broadened absorption bands, such as those encountered in rare earth ion doped crystals and atomic gases in external gradient magnetic field. Protocols based on electromagnetic induced transparency also rely on resonant excitation and are ideally suited to the homogeneous absorption lines offered by laser cooled atomic clouds or ion Coulomb crystals. Finally off-resonance approaches are illustrated by Faraday and Raman processes. Coupling with an optical cavity may enhance the storage process, even for negligibly small atom number. Multiple scattering is also proposed as a way to enlarge the quantum interaction distance of light with matter. The quest for higher efficiency, better fidelity, broader bandwidth, multimode capacity and longer storage lifetime is pursued in all those approaches, as shown in this special issue. The improvement of quantum memory operation specifically requires in-depth study and control of numerous physical processes leading to atomic decoherence. The present issue reflects the development of rare earth ion doped matrices offering long lifetime superposition states, either as bulk crystals or as optical waveguides. The need for quantum sources and high efficiency detectors at the single photon level is also illustrated. Several papers address the networking of quantum memories either in long-haul cryptography or in the prospect of quantum processing. In this context, much attention has been paid recently to interfacing quantum light with superconducting qubits and with nitrogen-vacancy centers in diamond. Finally, the quantum interfacing of light with matter raises questions on entanglement. The last two papers are devoted to the generation of entanglement by dissipative processes. It is shown that long lifetime entanglement may be built in this way. We hope this special issue will help readers to become familiar with the exciting field of ensemble-based quantum memories and will stimulate them to bring deeper insights and new ideas to this area.

FIBRE AND INTEGRATED OPTICS. OPTICAL PROCESSING OF INFORMATION: Method for optical data processing based on a two-pulse photon echo

NASA Astrophysics Data System (ADS)

Zakharov, S. M.; Manykin, Eduard A.

1995-02-01

The principles of optical processing based on dynamic spatial—temporal properties of two-pulse photon echo signals are considered. The properties of a resonant medium as an on-line filter of temporal and spatial frequencies are discussed. These properties are due to the sensitivity of such a medium to the Fourier spectrum of the second exiting pulse. Degeneracy of quantum resonant systems, demonstrated by the coherent response dependence on the square of the amplitude of the second pulse, can be used for 'simultaneous' correlation processing of optical 'signals'. Various methods for the processing of the Fourier optical image are discussed.

Different valence Sn doping - A simple way to detect oxygen concentration variation of ZnO quantum dots synthesized under ultrasonic irradiation.

PubMed

Yang, Weimin; Zhang, Bing; Zhang, Qitu; Wang, Lixi; Song, Bo; Wu, Fan; Wong, C P

2017-09-01

An ultrasonic method is employed to synthesize the Sn doped Zn 0.95 Sn 0.05 O quantum dots with green light emission. Sn 2+ and Sn 4+ ions are used to create different optical defects inside Zn 0.95 Sn 0.05 O quantum dots and the changing trend of oxygen concentration under different ultrasonic irradiation power are investigated. The photoluminescence spectra are employed to characterize the optical defects of Zn 0.95 Sn 0.05 O quantum dots. The UV-vis spectra are used to study the band gap of Zn 0.95 Sn 0.05 O quantum dots, which is influenced by their sizes. The results indicate that ultrasonic power would influence the size of Zn 0.95 Sn 0.05 O quantum dots as well as the type and quantity of defects in ZnO quantum dots. Changing trends in size of Sn 2+ and Sn 4+ doped Zn 0.95 Sn 0.05 O quantum dots are quite similar with each other, while the changing trends in optical defects types and concentration of Sn 2+ and Sn 4+ doped Zn 0.95 Sn 0.05 O quantum dots are different. The difference of the optical defects concentration changing between Sn 2+ doped Zn 0.95 Sn 0.05 O quantum dots (V O defects) and Sn 4+ doped Zn 0.95 Sn 0.05 O quantum dots (O Zn and O i defects) shows that the formation process of ZnO under ultrasonic irradiation wiped oxygen out. Copyright © 2017 Elsevier B.V. All rights reserved.

Universal Quantum Computing with Measurement-Induced Continuous-Variable Gate Sequence in a Loop-Based Architecture.

PubMed

Takeda, Shuntaro; Furusawa, Akira

2017-09-22

We propose a scalable scheme for optical quantum computing using measurement-induced continuous-variable quantum gates in a loop-based architecture. Here, time-bin-encoded quantum information in a single spatial mode is deterministically processed in a nested loop by an electrically programmable gate sequence. This architecture can process any input state and an arbitrary number of modes with almost minimum resources, and offers a universal gate set for both qubits and continuous variables. Furthermore, quantum computing can be performed fault tolerantly by a known scheme for encoding a qubit in an infinite-dimensional Hilbert space of a single light mode.

Universal Quantum Computing with Measurement-Induced Continuous-Variable Gate Sequence in a Loop-Based Architecture

NASA Astrophysics Data System (ADS)

Takeda, Shuntaro; Furusawa, Akira

2017-09-01

We propose a scalable scheme for optical quantum computing using measurement-induced continuous-variable quantum gates in a loop-based architecture. Here, time-bin-encoded quantum information in a single spatial mode is deterministically processed in a nested loop by an electrically programmable gate sequence. This architecture can process any input state and an arbitrary number of modes with almost minimum resources, and offers a universal gate set for both qubits and continuous variables. Furthermore, quantum computing can be performed fault tolerantly by a known scheme for encoding a qubit in an infinite-dimensional Hilbert space of a single light mode.

Scalable Engineering of Quantum Optical Information Processing Architectures (SEQUOIA)

DTIC Science & Technology

2016-12-13

arrays. Figure 4: An 8-channel fiber-coupled SNSPD array. 1.4 Post -fabrication-tunable linear optic fabrication We have analyzed the...performance of the programmable nanophotonic processor (PNP) that is dynamically tunable via post -fabrication active phase tuning to predict the scaling of...various device losses. PACS numbers: 42.50. Ex , 03.67.Dd, 03.67.Lx, 42.50.Dv I. INTRODUCTION Quantum key distribution (QKD) enables two distant authenticated

Synthetic-lattice enabled all-optical devices based on orbital angular momentum of light.

PubMed

Luo, Xi-Wang; Zhou, Xingxiang; Xu, Jin-Shi; Li, Chuan-Feng; Guo, Guang-Can; Zhang, Chuanwei; Zhou, Zheng-Wei

2017-07-14

All-optical photonic devices are crucial for many important photonic technologies and applications, ranging from optical communication to quantum information processing. Conventional design of all-optical devices is based on photon propagation and interference in real space, which may rely on large numbers of optical elements, and the requirement of precise control makes this approach challenging. Here we propose an unconventional route for engineering all-optical devices using the photon's internal degrees of freedom, which form photonic crystals in such synthetic dimensions for photon propagation and interference. We demonstrate this design concept by showing how important optical devices such as quantum memory and optical filters can be realized using synthetic orbital angular momentum (OAM) lattices in degenerate cavities. The design route utilizing synthetic photonic lattices may significantly reduce the requirement for numerous optical elements and their fine tuning in conventional design, paving the way for realistic all-optical photonic devices with novel functionalities.

Cavity-based quantum networks with single atoms and optical photons

NASA Astrophysics Data System (ADS)

Reiserer, Andreas; Rempe, Gerhard

2015-10-01

Distributed quantum networks will allow users to perform tasks and to interact in ways which are not possible with present-day technology. Their implementation is a key challenge for quantum science and requires the development of stationary quantum nodes that can send and receive as well as store and process quantum information locally. The nodes are connected by quantum channels for flying information carriers, i.e., photons. These channels serve both to directly exchange quantum information between nodes and to distribute entanglement over the whole network. In order to scale such networks to many particles and long distances, an efficient interface between the nodes and the channels is required. This article describes the cavity-based approach to this goal, with an emphasis on experimental systems in which single atoms are trapped in and coupled to optical resonators. Besides being conceptually appealing, this approach is promising for quantum networks on larger scales, as it gives access to long qubit coherence times and high light-matter coupling efficiencies. Thus, it allows one to generate entangled photons on the push of a button, to reversibly map the quantum state of a photon onto an atom, to transfer and teleport quantum states between remote atoms, to entangle distant atoms, to detect optical photons nondestructively, to perform entangling quantum gates between an atom and one or several photons, and even provides a route toward efficient heralded quantum memories for future repeaters. The presented general protocols and the identification of key parameters are applicable to other experimental systems.

A quantum optical transistor with a single quantum dot in a photonic crystal nanocavity.

PubMed

Li, Jin-Jin; Zhu, Ka-Di

2011-02-04

Laser and strong coupling can coexist in a single quantum dot (QD) coupled to a photonic crystal nanocavity. This provides an important clue towards the realization of a quantum optical transistor. Using experimentally realistic parameters, in this work, theoretical analysis shows that such a quantum optical transistor can be switched on or off by turning on or off the pump laser, which corresponds to attenuation or amplification of the probe laser, respectively. Furthermore, based on this quantum optical transistor, an all-optical measurement of the vacuum Rabi splitting is also presented. The idea of associating a quantum optical transistor with this coupled QD-nanocavity system may achieve images of light controlling light in all-optical logic circuits and quantum computers.

Active temporal multiplexing of indistinguishable heralded single photons

PubMed Central

Xiong, C.; Zhang, X.; Liu, Z.; Collins, M. J.; Mahendra, A.; Helt, L. G.; Steel, M. J.; Choi, D. -Y.; Chae, C. J.; Leong, P. H. W.; Eggleton, B. J.

2016-01-01

It is a fundamental challenge in quantum optics to deterministically generate indistinguishable single photons through non-deterministic nonlinear optical processes, due to the intrinsic coupling of single- and multi-photon-generation probabilities in these processes. Actively multiplexing photons generated in many temporal modes can decouple these probabilities, but key issues are to minimize resource requirements to allow scalability, and to ensure indistinguishability of the generated photons. Here we demonstrate the multiplexing of photons from four temporal modes solely using fibre-integrated optics and off-the-shelf electronic components. We show a 100% enhancement to the single-photon output probability without introducing additional multi-photon noise. Photon indistinguishability is confirmed by a fourfold Hong–Ou–Mandel quantum interference with a 91±16% visibility after subtracting multi-photon noise due to high pump power. Our demonstration paves the way for scalable multiplexing of many non-deterministic photon sources to a single near-deterministic source, which will be of benefit to future quantum photonic technologies. PMID:26996317

Quantum-coherent coupling of a mechanical oscillator to an optical cavity mode.

PubMed

Verhagen, E; Deléglise, S; Weis, S; Schliesser, A; Kippenberg, T J

2012-02-01

Optical laser fields have been widely used to achieve quantum control over the motional and internal degrees of freedom of atoms and ions, molecules and atomic gases. A route to controlling the quantum states of macroscopic mechanical oscillators in a similar fashion is to exploit the parametric coupling between optical and mechanical degrees of freedom through radiation pressure in suitably engineered optical cavities. If the optomechanical coupling is 'quantum coherent'--that is, if the coherent coupling rate exceeds both the optical and the mechanical decoherence rate--quantum states are transferred from the optical field to the mechanical oscillator and vice versa. This transfer allows control of the mechanical oscillator state using the wide range of available quantum optical techniques. So far, however, quantum-coherent coupling of micromechanical oscillators has only been achieved using microwave fields at millikelvin temperatures. Optical experiments have not attained this regime owing to the large mechanical decoherence rates and the difficulty of overcoming optical dissipation. Here we achieve quantum-coherent coupling between optical photons and a micromechanical oscillator. Simultaneously, coupling to the cold photon bath cools the mechanical oscillator to an average occupancy of 1.7 ± 0.1 motional quanta. Excitation with weak classical light pulses reveals the exchange of energy between the optical light field and the micromechanical oscillator in the time domain at the level of less than one quantum on average. This optomechanical system establishes an efficient quantum interface between mechanical oscillators and optical photons, which can provide decoherence-free transport of quantum states through optical fibres. Our results offer a route towards the use of mechanical oscillators as quantum transducers or in microwave-to-optical quantum links.

Detection of Biochemical Pathogens, Laser Stand-off Spectroscopy, Quantum Coherence, and Many Body Quantum Optics

DTIC Science & Technology

2012-02-24

AND SUBTITLE Detection of Biochemical Pathogens, Laser Stand-off Spectroscopy, Quantum Coherence, and Many Body Quantum Optics 6. AUTHORS Marian O...Maximum 200 words) Results of our earlier research in the realm of quantum optics were extended in order to solve the challenging technical problems of...efficient methods of generating UV light via quantum coherence. 14. SUBJECT TERMS Quantum coherence, quantum optics, lasers 15. NUMBER OF PAGES 15

Hyper-branched CdTe nanostructures based on the self-assembling of quantum dots and their optical properties.

PubMed

Pan, Ling-Yun; Pan, Gen-Cai; Zhang, Yong-Lai; Gao, Bing-Rong; Dai, Zhen-Wen

2013-02-01

As the priority of interconnects and active components in nanoscale optical and electronic devices, three-dimensional hyper-branched nanostructures came into focus of research. Recently, a novel crystallization route, named as "nonclassical crystallization," has been reported for three-dimensional nanostructuring. In this process, Quantum dots are used as building blocks for the construction of the whole hyper-branched structures instead of ions or single-molecules in conventional crystallization. The specialty of these nanostructures is the inheritability of pristine quantum dots' physical integrity because of their polycrystalline structures, such as quantum confinement effect and thus the luminescence. Moreover, since a longer diffusion length could exist in polycrystalline nanostructures due to the dramatically decreased distance between pristine quantum dots, the exciton-exciton interaction would be different with well dispersed quantum dots and single crystal nanostructures. This may be a benefit for electron transport in solar cell application. Therefore, it is very necessary to investigate the exciton-exciton interaction in such kind of polycrystalline nanostructures and their optical properites for solar cell application. In this research, we report a novel CdTe hyper-branched nanostructures based on self-assembly of CdTe quantum dots. Each branch shows polycrystalline with pristine quantum dots as the building units. Both steady state and time-resolved spectroscopy were performed to investigate the properties of carrier transport. Steady state optical properties of pristine quantum dots are well inherited by formed structures. While a suppressed multi-exciton recombination rate was observed. This result supports the percolation of carriers through the branches' network.

Experimental teleportation of a quantum controlled-NOT gate.

PubMed

Huang, Yun-Feng; Ren, Xi-Feng; Zhang, Yong-Sheng; Duan, Lu-Ming; Guo, Guang-Can

2004-12-10

Teleportation of quantum gates is a critical step for the implementation of quantum networking and teleportation-based models of quantum computation. We report an experimental demonstration of teleportation of the prototypical quantum controlled-NOT (CNOT) gate. Assisted with linear optical manipulations, photon entanglement produced from parametric down-conversion, and postselection from the coincidence measurements, we teleport the quantum CNOT gate from acting on local qubits to acting on remote qubits. The quality of the quantum gate teleportation is characterized through the method of quantum process tomography, with an average fidelity of 0.84 demonstrated for the teleported gate.

Storage and retrieval of vector beams of light in a multiple-degree-of-freedom quantum memory.

PubMed

Parigi, Valentina; D'Ambrosio, Vincenzo; Arnold, Christophe; Marrucci, Lorenzo; Sciarrino, Fabio; Laurat, Julien

2015-07-13

The full structuration of light in the transverse plane, including intensity, phase and polarization, holds the promise of unprecedented capabilities for applications in classical optics as well as in quantum optics and information sciences. Harnessing special topologies can lead to enhanced focusing, data multiplexing or advanced sensing and metrology. Here we experimentally demonstrate the storage of such spatio-polarization-patterned beams into an optical memory. A set of vectorial vortex modes is generated via liquid crystal cell with topological charge in the optic axis distribution, and preservation of the phase and polarization singularities is demonstrated after retrieval, at the single-photon level. The realized multiple-degree-of-freedom memory can find applications in classical data processing but also in quantum network scenarios where structured states have been shown to provide promising attributes, such as rotational invariance.

Storage and retrieval of vector beams of light in a multiple-degree-of-freedom quantum memory

PubMed Central

Parigi, Valentina; D'Ambrosio, Vincenzo; Arnold, Christophe; Marrucci, Lorenzo; Sciarrino, Fabio; Laurat, Julien

2015-01-01

The full structuration of light in the transverse plane, including intensity, phase and polarization, holds the promise of unprecedented capabilities for applications in classical optics as well as in quantum optics and information sciences. Harnessing special topologies can lead to enhanced focusing, data multiplexing or advanced sensing and metrology. Here we experimentally demonstrate the storage of such spatio-polarization-patterned beams into an optical memory. A set of vectorial vortex modes is generated via liquid crystal cell with topological charge in the optic axis distribution, and preservation of the phase and polarization singularities is demonstrated after retrieval, at the single-photon level. The realized multiple-degree-of-freedom memory can find applications in classical data processing but also in quantum network scenarios where structured states have been shown to provide promising attributes, such as rotational invariance. PMID:26166257

Topics in linear optical quantum computation

NASA Astrophysics Data System (ADS)

Glancy, Scott Charles

This thesis covers several topics in optical quantum computation. A quantum computer is a computational device which is able to manipulate information by performing unitary operations on some physical system whose state can be described as a vector (or mixture of vectors) in a Hilbert space. The basic unit of information, called the qubit, is considered to be a system with two orthogonal states, which are assigned logical values of 0 and 1. Photons make excellent candidates to serve as qubits. They have little interactions with the environment. Many operations can be performed using very simple linear optical devices such as beam splitters and phase shifters. Photons can easily be processed through circuit-like networks. Operations can be performed in very short times. Photons are ideally suited for the long-distance communication of quantum information. The great difficulty in constructing an optical quantum computer is that photons naturally interact weakly with one another. This thesis first gives a brief review of two early approaches to optical quantum computation. It will describe how any discrete unitary operation can be performed using a single photon and a network of beam splitters, and how the Kerr effect can be used to construct a two photon logic gate. Second, this work provides a thorough introduction to the linear optical quantum computer developed by Knill, Laflamme, and Milburn. It then presents this author's results on the reliability of this scheme when implemented using imperfect photon detectors. This author finds that quantum computers of this sort cannot be built using current technology. Third, this dissertation describes a method for constructing a linear optical quantum computer using nearly orthogonal coherent states of light as the qubits. It shows how a universal set of logic operations can be performed, including calculations of the fidelity with which these operations may be accomplished. It discusses methods for reducing and correcting errors and recovering from failed operations. Lastly it describes an analysis of the long distance transmission of the coherent state qubits and shows how transmission errors can be corrected.

Quantum Nonlinear Optics without real Photons

NASA Astrophysics Data System (ADS)

Macrí, Vincenzo; Frisk Kockum, Anton; Stassi, Roberto; di Stefano, Omar; Savasta, Salvatore; Nori, Franco

We propose a physical process analogous to spontaneous parametric down-conversion, where one excited atom directly transfers its excitation to a couple of spatially-separated atoms with probability approaching one. The interaction is mediated by the exchange of virtual, rather than real, photons. This nonlinear optical process is coherent and reversible, so that the two excited atoms can transfer back the excitation to the first one: the atomic analogue of sum-frequency generation. The parameters used here correspond to experimentally-demonstrated values in circuit QED. This approach can be extended to consider other nonlinear interatomic processes, e.g. four-qubit mixing, and is an attractive architecture for the realization of quantum devices on a chip. Univ. of Michigan, USA.

Quantum Nonlinear Optics without Photons

NASA Astrophysics Data System (ADS)

Macrı, Vincenzo

Here we propose a physical process analogous to spontaneous parametric down-conversion, where one excited atom directly transfers its excitation to a couple of spatially separated atoms with probability approaching one. The interaction is mediated by the exchange of virtual rather than real photons. This nonlinear optical process is coherent and reversible, so that the couple of excited atoms can transfer back the excitation to the first one: the analogous for atoms of sum-frequency generation. The parameters used here correspond to experimentally-demonstrated values in circuit QED. This approach can be expanded to consider other nonlinear inter-atomic processes as the four-qubit mixing and is an attractive architecture for the realization of quantum devices on a chip.

Microscopic Modeling of Intersubband Optical Processes in Type II Semiconductor Quantum Wells: Linear Absorption

NASA Technical Reports Server (NTRS)

Li, Jian-Zhong; Kolokolov, Kanstantin I.; Ning, Cun-Zheng

2003-01-01

Linear absorption spectra arising from intersubband transitions in semiconductor quantum well heterostructures are analyzed using quantum kinetic theory by treating correlations to the first order within Hartree-Fock approximation. The resulting intersubband semiconductor Bloch equations take into account extrinsic dephasing contributions, carrier-longitudinal optical phonon interaction and carrier-interface roughness interaction which is considered with Ando s theory. As input for resonance lineshape calculation, a spurious-states-free 8-band kp Hamiltonian is used, in conjunction with the envelop function approximation, to compute self-consistently the energy subband structure of electrons in type II InAs/AlSb single quantum well structures. We demonstrate the interplay of nonparabolicity and many-body effects in the mid-infrared frequency range for such heterostructures.

Entanglement and Wigner Function Negativity of Multimode Non-Gaussian States

NASA Astrophysics Data System (ADS)

Walschaers, Mattia; Fabre, Claude; Parigi, Valentina; Treps, Nicolas

2017-11-01

Non-Gaussian operations are essential to exploit the quantum advantages in optical continuous variable quantum information protocols. We focus on mode-selective photon addition and subtraction as experimentally promising processes to create multimode non-Gaussian states. Our approach is based on correlation functions, as is common in quantum statistical mechanics and condensed matter physics, mixed with quantum optics tools. We formulate an analytical expression of the Wigner function after the subtraction or addition of a single photon, for arbitrarily many modes. It is used to demonstrate entanglement properties specific to non-Gaussian states and also leads to a practical and elegant condition for Wigner function negativity. Finally, we analyze the potential of photon addition and subtraction for an experimentally generated multimode Gaussian state.

Entanglement and Wigner Function Negativity of Multimode Non-Gaussian States.

PubMed

Walschaers, Mattia; Fabre, Claude; Parigi, Valentina; Treps, Nicolas

2017-11-03

Non-Gaussian operations are essential to exploit the quantum advantages in optical continuous variable quantum information protocols. We focus on mode-selective photon addition and subtraction as experimentally promising processes to create multimode non-Gaussian states. Our approach is based on correlation functions, as is common in quantum statistical mechanics and condensed matter physics, mixed with quantum optics tools. We formulate an analytical expression of the Wigner function after the subtraction or addition of a single photon, for arbitrarily many modes. It is used to demonstrate entanglement properties specific to non-Gaussian states and also leads to a practical and elegant condition for Wigner function negativity. Finally, we analyze the potential of photon addition and subtraction for an experimentally generated multimode Gaussian state.

Experimental entanglement of 25 individually accessible atomic quantum interfaces

PubMed Central

Jiang, Nan; Chang, Wei; Li, Chang; Zhang, Sheng

2018-01-01

A quantum interface links the stationary qubits in a quantum memory with flying photonic qubits in optical transmission channels and constitutes a critical element for the future quantum internet. Entanglement of quantum interfaces is an important step for the realization of quantum networks. Through heralded detection of photon interference, we generate multipartite entanglement between 25 (or 9) individually addressable quantum interfaces in a multiplexed atomic quantum memory array and confirm genuine 22-partite (or 9-partite) entanglement. This experimental entanglement of a record-high number of individually addressable quantum interfaces makes an important step toward the realization of quantum networks, long-distance quantum communication, and multipartite quantum information processing. PMID:29725621

Experimental demonstration of graph-state quantum secret sharing.

PubMed

Bell, B A; Markham, D; Herrera-Martí, D A; Marin, A; Wadsworth, W J; Rarity, J G; Tame, M S

2014-11-21

Quantum communication and computing offer many new opportunities for information processing in a connected world. Networks using quantum resources with tailor-made entanglement structures have been proposed for a variety of tasks, including distributing, sharing and processing information. Recently, a class of states known as graph states has emerged, providing versatile quantum resources for such networking tasks. Here we report an experimental demonstration of graph state-based quantum secret sharing--an important primitive for a quantum network with applications ranging from secure money transfer to multiparty quantum computation. We use an all-optical setup, encoding quantum information into photons representing a five-qubit graph state. We find that one can reliably encode, distribute and share quantum information amongst four parties, with various access structures based on the complex connectivity of the graph. Our results show that graph states are a promising approach for realising sophisticated multi-layered communication protocols in quantum networks.

Remote preparation of an atomic quantum memory.

PubMed

Rosenfeld, Wenjamin; Berner, Stefan; Volz, Jürgen; Weber, Markus; Weinfurter, Harald

2007-02-02

Storage and distribution of quantum information are key elements of quantum information processing and future quantum communication networks. Here, using atom-photon entanglement as the main physical resource, we experimentally demonstrate the preparation of a distant atomic quantum memory. Applying a quantum teleportation protocol on a locally prepared state of a photonic qubit, we realized this so-called remote state preparation on a single, optically trapped 87Rb atom. We evaluated the performance of this scheme by the full tomography of the prepared atomic state, reaching an average fidelity of 82%.

Ion-photon entanglement and quantum frequency conversion with trapped Ba⁺ ions.

PubMed

Siverns, J D; Li, X; Quraishi, Q

2017-01-20

Trapped ions are excellent candidates for quantum nodes, as they possess many desirable features of a network node including long lifetimes, on-site processing capability, and production of photonic flying qubits. However, unlike classical networks in which data may be transmitted in optical fibers and where the range of communication is readily extended with amplifiers, quantum systems often emit photons that have a limited propagation range in optical fibers and, by virtue of the nature of a quantum state, cannot be noiselessly amplified. Here, we first describe a method to extract flying qubits from a Ba⁺ trapped ion via shelving to a long-lived, low-lying D-state with higher entanglement probabilities compared with current strong and weak excitation methods. We show a projected fidelity of ≈89% of the ion-photon entanglement. We compare several methods of ion-photon entanglement generation, and we show how the fidelity and entanglement probability varies as a function of the photon collection optic's numerical aperture. We then outline an approach for quantum frequency conversion of the photons emitted by the Ba⁺ ion to the telecommunication range for long-distance networking and to 780 nm for potential entanglement with rubidium-based quantum memories. Our approach is significant for extending the range of quantum networks and for the development of hybrid quantum networks compromised of different types of quantum memories.

Multimodal properties and dynamics of gradient echo quantum memory.

PubMed

Hétet, G; Longdell, J J; Sellars, M J; Lam, P K; Buchler, B C

2008-11-14

We investigate the properties of a recently proposed gradient echo memory (GEM) scheme for information mapping between optical and atomic systems. We show that GEM can be described by the dynamic formation of polaritons in k space. This picture highlights the flexibility and robustness with regards to the external control of the storage process. Our results also show that, as GEM is a frequency-encoding memory, it can accurately preserve the shape of signals that have large time-bandwidth products, even at moderate optical depths. At higher optical depths, we show that GEM is a high fidelity multimode quantum memory.

Terahertz generation by difference frequency generation from a compact optical parametric oscillator

NASA Astrophysics Data System (ADS)

Li, Zhongyang; Wang, Silei; Wang, Mengtao; Wang, Weishu

2017-11-01

Terahertz (THz) generation by difference frequency generation (DFG) processes with dual idler waves is theoretically analyzed. The dual idler waves are generated by a compact optical parametric oscillator (OPO) with periodically poled lithium niobate (PPLN). The phase-matching conditions in a same PPLN for the optical parametric oscillation generating signal and idler waves and for the DFG generating THz waves can be simultaneously satisfied by selecting the poling period of PPLN. Moreover, 3-order cascaded DFG processes generating THz waves can be realized in the same PPLN. To take an example of 8.341 THz which locates in the vicinity of polariton resonances, THz intensities and quantum conversion efficiencies are calculated. Compared with non-cascaded DFG processes, THz intensities of 8.341 THz in 3-order cascaded DFG processes increase to 2.57 times. When the pump intensity equals to 20 MW/mm2, the quantum conversion efficiency of 106% in 3-order cascaded DFG processes can be realized, which exceeds the Manley-Rowe limit.

Hybrid quantum processors: molecular ensembles as quantum memory for solid state circuits.

PubMed

Rabl, P; DeMille, D; Doyle, J M; Lukin, M D; Schoelkopf, R J; Zoller, P

2006-07-21

We investigate a hybrid quantum circuit where ensembles of cold polar molecules serve as long-lived quantum memories and optical interfaces for solid state quantum processors. The quantum memory realized by collective spin states (ensemble qubit) is coupled to a high-Q stripline cavity via microwave Raman processes. We show that, for convenient trap-surface distances of a few microm, strong coupling between the cavity and ensemble qubit can be achieved. We discuss basic quantum information protocols, including a swap from the cavity photon bus to the molecular quantum memory, and a deterministic two qubit gate. Finally, we investigate coherence properties of molecular ensemble quantum bits.

Quantum-classical boundary for precision optical phase estimation

NASA Astrophysics Data System (ADS)

Birchall, Patrick M.; O'Brien, Jeremy L.; Matthews, Jonathan C. F.; Cable, Hugo

2017-12-01

Understanding the fundamental limits on the precision to which an optical phase can be estimated is of key interest for many investigative techniques utilized across science and technology. We study the estimation of a fixed optical phase shift due to a sample which has an associated optical loss, and compare phase estimation strategies using classical and nonclassical probe states. These comparisons are based on the attainable (quantum) Fisher information calculated per number of photons absorbed or scattered by the sample throughout the sensing process. We find that for a given number of incident photons upon the unknown phase, nonclassical techniques in principle provide less than a 20 % reduction in root-mean-square error (RMSE) in comparison with ideal classical techniques in multipass optical setups. Using classical techniques in a different optical setup that we analyze, which incorporates additional stages of interference during the sensing process, the achievable reduction in RMSE afforded by nonclassical techniques falls to only ≃4 % . We explain how these conclusions change when nonclassical techniques are compared to classical probe states in nonideal multipass optical setups, with additional photon losses due to the measurement apparatus.

Polarized electrons, trions, and nuclei in charged quantum dots

NASA Astrophysics Data System (ADS)

Bracker, A. S.; Tischler, J. G.; Korenev, V. L.; Gammon, D.

2003-07-01

We have investigated spin polarization in GaAs quantum dots. Excitons and trions are polarized directly by optical excitation and studied through polarization of photoluminescence. Electrons and nuclei are polarized indirectly through subsequent relaxation processes. Polarized electrons are identified by the Hanle effect for exciton and trion photoluminescence, while polarized nuclei are identified through the Overhauser effect in individual charged quantum dots.

Many-body exciton states in self-assembled quantum dots coupled to a Fermi sea

NASA Astrophysics Data System (ADS)

Kleemans, N. A. J. M.; van Bree, J.; Govorov, A. O.; Keizer, J. G.; Hamhuis, G. J.; Nötzel, R.; Silov, A. Yu.; Koenraad, P. M.

2010-07-01

Many-body interactions give rise to fascinating physics such as the X-ray Fermi-edge singularity in metals, the Kondo effect in the resistance of metals with magnetic impurities and the fractional quantum Hall effect. Here we report the observation of striking many-body effects in the optical spectra of a semiconductor quantum dot interacting with a degenerate electron gas. A semiconductor quantum dot is an artificial atom, the properties of which can be controlled by means of a tunnel coupling between a metallic contact and the quantum dot. Previous studies concern mostly the regime of weak tunnel coupling, whereas here we investigate the regime of strong coupling, which markedly modifies the optical spectra. In particular we observe two many-body exciton states: Mahan and hybrid excitons. These experimental results open the route towards the observation of a tunable Kondo effect in excited states of semiconductors and are of importance for the technological implementation of quantum dots in devices for quantum information processing.

Quantum optical emulation of molecular vibronic spectroscopy using a trapped-ion device.

PubMed

Shen, Yangchao; Lu, Yao; Zhang, Kuan; Zhang, Junhua; Zhang, Shuaining; Huh, Joonsuk; Kim, Kihwan

2018-01-28

Molecules are one of the most demanding quantum systems to be simulated by quantum computers due to their complexity and the emergent role of quantum nature. The recent theoretical proposal of Huh et al. (Nature Photon., 9, 615 (2015)) showed that a multi-photon network with a Gaussian input state can simulate a molecular spectroscopic process. Here, we present the first quantum device that generates a molecular spectroscopic signal with the phonons in a trapped ion system, using SO 2 as an example. In order to perform reliable Gaussian sampling, we develop the essential experimental technology with phonons, which includes the phase-coherent manipulation of displacement, squeezing, and rotation operations with multiple modes in a single realization. The required quantum optical operations are implemented through Raman laser beams. The molecular spectroscopic signal is reconstructed from the collective projection measurements for the two-phonon-mode. Our experimental demonstration will pave the way to large-scale molecular quantum simulations, which are classically intractable, but would be easily verifiable by real molecular spectroscopy.

A multiplexed quantum memory.

PubMed

Lan, S-Y; Radnaev, A G; Collins, O A; Matsukevich, D N; Kennedy, T A; Kuzmich, A

2009-08-03

A quantum repeater is a system for long-distance quantum communication that employs quantum memory elements to mitigate optical fiber transmission losses. The multiplexed quantum memory (O. A. Collins, S. D. Jenkins, A. Kuzmich, and T. A. B. Kennedy, Phys. Rev. Lett. 98, 060502 (2007)) has been shown theoretically to reduce quantum memory time requirements. We present an initial implementation of a multiplexed quantum memory element in a cold rubidium gas. We show that it is possible to create atomic excitations in arbitrary memory element pairs and demonstrate the violation of Bell's inequality for light fields generated during the write and read processes.

Entanglement distribution schemes employing coherent photon-to-spin conversion in semiconductor quantum dot circuits

NASA Astrophysics Data System (ADS)

Gaudreau, Louis; Bogan, Alex; Korkusinski, Marek; Studenikin, Sergei; Austing, D. Guy; Sachrajda, Andrew S.

2017-09-01

Long distance entanglement distribution is an important problem for quantum information technologies to solve. Current optical schemes are known to have fundamental limitations. A coherent photon-to-spin interface built with quantum dots (QDs) in a direct bandgap semiconductor can provide a solution for efficient entanglement distribution. QD circuits offer integrated spin processing for full Bell state measurement (BSM) analysis and spin quantum memory. Crucially the photo-generated spins can be heralded by non-destructive charge detection techniques. We review current schemes to transfer a polarization-encoded state or a time-bin-encoded state of a photon to the state of a spin in a QD. The spin may be that of an electron or that of a hole. We describe adaptations of the original schemes to employ heavy holes which have a number of attractive properties including a g-factor that is tunable to zero for QDs in an appropriately oriented external magnetic field. We also introduce simple throughput scaling models to demonstrate the potential performance advantage of full BSM capability in a QD scheme, even when the quantum memory is imperfect, over optical schemes relying on linear optical elements and ensemble quantum memories.

Pure sources and efficient detectors for optical quantum information processing

NASA Astrophysics Data System (ADS)

Zielnicki, Kevin

Over the last sixty years, classical information theory has revolutionized the understanding of the nature of information, and how it can be quantified and manipulated. Quantum information processing extends these lessons to quantum systems, where the properties of intrinsic uncertainty and entanglement fundamentally defy classical explanation. This growing field has many potential applications, including computing, cryptography, communication, and metrology. As inherently mobile quantum particles, photons are likely to play an important role in any mature large-scale quantum information processing system. However, the available methods for producing and detecting complex multi-photon states place practical limits on the feasibility of sophisticated optical quantum information processing experiments. In a typical quantum information protocol, a source first produces an interesting or useful quantum state (or set of states), perhaps involving superposition or entanglement. Then, some manipulations are performed on this state, perhaps involving quantum logic gates which further manipulate or entangle the intial state. Finally, the state must be detected, obtaining some desired measurement result, e.g., for secure communication or computationally efficient factoring. The work presented here concerns the first and last stages of this process as they relate to photons: sources and detectors. Our work on sources is based on the need for optimized non-classical states of light delivered at high rates, particularly of single photons in a pure quantum state. We seek to better understand the properties of spontaneous parameteric downconversion (SPDC) sources of photon pairs, and in doing so, produce such an optimized source. We report an SPDC source which produces pure heralded single photons with little or no spectral filtering, allowing a significant rate enhancement. Our work on detectors is based on the need to reliably measure single-photon states. We have focused on optimizing the detection efficiency of visible light photon counters (VLPCs), a single-photon detection technology that is also capable of resolving photon number states. We report a record-breaking quantum efficiency of 91 +/- 3% observed with our detection system. Both sources and detectors are independently interesting physical systems worthy of study, but together they promise to enable entire new classes and applications of information based on quantum mechanics.

Deterministic quantum nonlinear optics with single atoms and virtual photons

NASA Astrophysics Data System (ADS)

Kockum, Anton Frisk; Miranowicz, Adam; Macrı, Vincenzo; Savasta, Salvatore; Nori, Franco

2017-06-01

We show how analogs of a large number of well-known nonlinear-optics phenomena can be realized with one or more two-level atoms coupled to one or more resonator modes. Through higher-order processes, where virtual photons are created and annihilated, an effective deterministic coupling between two states of such a system can be created. In this way, analogs of three-wave mixing, four-wave mixing, higher-harmonic and -subharmonic generation (i.e., up- and down-conversion), multiphoton absorption, parametric amplification, Raman and hyper-Raman scattering, the Kerr effect, and other nonlinear processes can be realized. In contrast to most conventional implementations of nonlinear optics, these analogs can reach unit efficiency, only use a minimal number of photons (they do not require any strong external drive), and do not require more than two atomic levels. The strength of the effective coupling in our proposed setups becomes weaker the more intermediate transition steps are needed. However, given the recent experimental progress in ultrastrong light-matter coupling and improvement of coherence times for engineered quantum systems, especially in the field of circuit quantum electrodynamics, we estimate that many of these nonlinear-optics analogs can be realized with currently available technology.

Quantum-entanglement storage and extraction in quantum network node

NASA Astrophysics Data System (ADS)

Shan, Zhuoyu; Zhang, Yong

Quantum computing and quantum communication have become the most popular research topic. Nitrogen-vacancy (NV) centers in diamond have been shown the great advantage of implementing quantum information processing. The generation of entanglement between NV centers represents a fundamental prerequisite for all quantum information technologies. In this paper, we propose a scheme to realize the high-fidelity storage and extraction of quantum entanglement information based on the NV centers at room temperature. We store the entangled information of a pair of entangled photons in the Bell state into the nuclear spins of two NV centers, which can make these two NV centers entangled. And then we illuminate how to extract the entangled information from NV centers to prepare on-demand entangled states for optical quantum information processing. The strategy of engineering entanglement demonstrated here maybe pave the way towards a NV center-based quantum network.

Photoelectron transport tuning of self-assembled subbands

NASA Astrophysics Data System (ADS)

Xiong, Zhengwei; Wang, Xinmin; Wu, Weidong; Wang, Xuemin; Peng, Liping; Zhao, Yan; Yan, Dawei; Jiang, Tao; Shen, Changle; Zhan, Zhiqiang; Cao, Linhong; Li, Weihua

2016-02-01

Conventionally, electrical transport of quantum subbands occurs at very high electric fields, indicating that the medium is easy to break down. In the experiments and practical applications, the extreme condition is difficult to satisfy. For quantum information transmission, low power consumption and convenient implementation are what we expect. In this paper, we engineered a special quantum dot array (QDA) embedded in a single crystal matrix. By external optical field excitation, we found a series of subbands made of the self-assembled QDA discretely located in the matrix. Changing the spacing between the quantum dots leads to the variation of subband spacing. Artificially manipulating the microcosmic QDA system can bring interesting macroscopic effects, such as an enhanced absorption intensity in the ultraviolet range, a blue-shift of the surface plasmon resonance peak and nonlinear absorption changed from two-photon absorption to saturated absorption. The intrinsic mechanism of the subband optical response was revealed due to the strong quantum confinement effect and dominant intraband transitions. The weak surface plasmon resonance absorption of Ni QDA gave an excellent figure of merit of the order of 10-10. The composite films are expectation enough to become a prime candidate for nonlinear applications near 532 nm. Therefore with interplay of the weak optical field and subbands, we achieved a tunable photoelectron transport process.Conventionally, electrical transport of quantum subbands occurs at very high electric fields, indicating that the medium is easy to break down. In the experiments and practical applications, the extreme condition is difficult to satisfy. For quantum information transmission, low power consumption and convenient implementation are what we expect. In this paper, we engineered a special quantum dot array (QDA) embedded in a single crystal matrix. By external optical field excitation, we found a series of subbands made of the self-assembled QDA discretely located in the matrix. Changing the spacing between the quantum dots leads to the variation of subband spacing. Artificially manipulating the microcosmic QDA system can bring interesting macroscopic effects, such as an enhanced absorption intensity in the ultraviolet range, a blue-shift of the surface plasmon resonance peak and nonlinear absorption changed from two-photon absorption to saturated absorption. The intrinsic mechanism of the subband optical response was revealed due to the strong quantum confinement effect and dominant intraband transitions. The weak surface plasmon resonance absorption of Ni QDA gave an excellent figure of merit of the order of 10-10. The composite films are expectation enough to become a prime candidate for nonlinear applications near 532 nm. Therefore with interplay of the weak optical field and subbands, we achieved a tunable photoelectron transport process. Electronic supplementary information (ESI) available: Tables 1 and 2. See DOI: 10.1039/c5nr07861j

Quantum Information Processing with Ferroelectrically Coupled Quantum Dots

DTIC Science & Technology

2010-12-05

on a chip applications. (a) Papers published in peer-reviewed journals (N/A for none) Y. Xi, Y. S. Jung , and H. K. Kim, “Interaction of light with a...metal wedge: the role of diffraction in shaping energy flow”, Optics Express 18, 2588-2600 (2010). Y. S. Jung , J. Wuenschell, H. K. Kim, P. Kaur, and D...H. Waldeck, “Blue-shift of surface plasmon resonance in a metal nanoslit array structure”, Optics Express 17, 16081-16091 (2009). Y. S. Jung , Y. Xi

Generalized optical angular momentum sorter and its application to high-dimensional quantum cryptography.

PubMed

Larocque, Hugo; Gagnon-Bischoff, Jérémie; Mortimer, Dominic; Zhang, Yingwen; Bouchard, Frédéric; Upham, Jeremy; Grillo, Vincenzo; Boyd, Robert W; Karimi, Ebrahim

2017-08-21

The orbital angular momentum (OAM) carried by optical beams is a useful quantity for encoding information. This form of encoding has been incorporated into various works ranging from telecommunications to quantum cryptography, most of which require methods that can rapidly process the OAM content of a beam. Among current state-of-the-art schemes that can readily acquire this information are so-called OAM sorters, which consist of devices that spatially separate the OAM components of a beam. Such devices have found numerous applications in optical communications, a field that is in constant demand for additional degrees of freedom, such as polarization and wavelength, into which information can also be encoded. Here, we report the implementation of a device capable of sorting a beam based on its OAM and polarization content, which could be of use in works employing both of these degrees of freedom as information channels. After characterizing our fabricated device, we demonstrate how it can be used for quantum communications via a quantum key distribution protocol.

A semiconductor photon-sorter

NASA Astrophysics Data System (ADS)

Bennett, A. J.; Lee, J. P.; Ellis, D. J. P.; Farrer, I.; Ritchie, D. A.; Shields, A. J.

2016-10-01

Obtaining substantial nonlinear effects at the single-photon level is a considerable challenge that holds great potential for quantum optical measurements and information processing. Of the progress that has been made in recent years one of the most promising methods is to scatter coherent light from quantum emitters, imprinting quantum correlations onto the photons. We report effective interactions between photons, controlled by a single semiconductor quantum dot that is weakly coupled to a monolithic cavity. We show that the nonlinearity of a transition modifies the counting statistics of a Poissonian beam, sorting the photons in number. This is used to create strong correlations between detection events and to create polarization-correlated photons from an uncorrelated stream using a single spin. These results pave the way for semiconductor optical switches operated by single quanta of light.

Quantum mechanical modeling the emission pattern and polarization of nanoscale light emitting diodes.

PubMed

Wang, Rulin; Zhang, Yu; Bi, Fuzhen; Frauenheim, Thomas; Chen, GuanHua; Yam, ChiYung

2016-07-21

Understanding of the electroluminescence (EL) mechanism in optoelectronic devices is imperative for further optimization of their efficiency and effectiveness. Here, a quantum mechanical approach is formulated for modeling the EL processes in nanoscale light emitting diodes (LED). Based on non-equilibrium Green's function quantum transport equations, interactions with the electromagnetic vacuum environment are included to describe electrically driven light emission in the devices. The presented framework is illustrated by numerical simulations of a silicon nanowire LED device. EL spectra of the nanowire device under different bias voltages are obtained and, more importantly, the radiation pattern and polarization of optical emission can be determined using the current approach. This work is an important step forward towards atomistic quantum mechanical modeling of the electrically induced optical response in nanoscale systems.

Study of the self-organization processes in lead sulfide quantum dots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tarasov, S. A., E-mail: SATarasov@mail.ru; Aleksandrova, O. A.; Maksimov, A. I.

A procedure is described for the synthesis of nanoparticles based on lead chalcogenides. The procedure combines the synthesis of colloidal quantum dots (QDs) in aqueous solutions with simultaneous organization of the QDs into ordered arrays. The processes of the self-organization of QDs are analyzed at the nano- and microscopic levels by the photoluminescence method, atomic-force microscopy, and optical microscopy.

Quantum optical signatures in strong-field laser physics: Infrared photon counting in high-order-harmonic generation.

PubMed

Gonoskov, I A; Tsatrafyllis, N; Kominis, I K; Tzallas, P

2016-09-07

We analytically describe the strong-field light-electron interaction using a quantized coherent laser state with arbitrary photon number. We obtain a light-electron wave function which is a closed-form solution of the time-dependent Schrödinger equation (TDSE). This wave function provides information about the quantum optical features of the interaction not accessible by semi-classical theories. With this approach we can reveal the quantum optical properties of high harmonic generation (HHG) process in gases by measuring the photon statistics of the transmitted infrared (IR) laser radiation. This work can lead to novel experiments in high-resolution spectroscopy in extreme-ultraviolet (XUV) and attosecond science without the need to measure the XUV light, while it can pave the way for the development of intense non-classical light sources.

Quantum entanglement between an optical photon and a solid-state spin qubit.

PubMed

Togan, E; Chu, Y; Trifonov, A S; Jiang, L; Maze, J; Childress, L; Dutt, M V G; Sørensen, A S; Hemmer, P R; Zibrov, A S; Lukin, M D

2010-08-05

Quantum entanglement is among the most fascinating aspects of quantum theory. Entangled optical photons are now widely used for fundamental tests of quantum mechanics and applications such as quantum cryptography. Several recent experiments demonstrated entanglement of optical photons with trapped ions, atoms and atomic ensembles, which are then used to connect remote long-term memory nodes in distributed quantum networks. Here we realize quantum entanglement between the polarization of a single optical photon and a solid-state qubit associated with the single electronic spin of a nitrogen vacancy centre in diamond. Our experimental entanglement verification uses the quantum eraser technique, and demonstrates that a high degree of control over interactions between a solid-state qubit and the quantum light field can be achieved. The reported entanglement source can be used in studies of fundamental quantum phenomena and provides a key building block for the solid-state realization of quantum optical networks.

Editorial . Quantum fluctuations and coherence in optical and atomic structures

NASA Astrophysics Data System (ADS)

Eschner, Jürgen; Gatti, Alessandra; Maître, Agnès; Morigi, Giovanna

2003-03-01

From simple interference fringes, over molecular wave packets, to nonlinear optical patterns - the fundamental interaction between light and matter leads to the formation of structures in many areas of atomic and optical physics. Sophisticated technology in experimental quantum optics, as well as modern computational tools available to theorists, have led to spectacular achievements in the investigation of quantum structures. This special issue is dedicated to recent developments in this area. It presents a selection of examples where quantum dynamics, fluctuations, and coherence generate structures in time or in space or where such structures are observed experimentally. The examples range from coherence phenomena in condensed matter, over atoms in optical structures, entanglement in light and matter, to quantum patterns in nonlinear optics and quantum imaging. The combination of such seemingly diverse subjects formed the basis of a successful European TMR network, "Quantum Structures" (visit http://cnqo.phys.strath.ac.uk/~gianluca/QSTRUCT/). This special issue partly re.ects the results and collaborations of the network, going however well beyond its scope by including contributions from a global community and from many related topics which were not addressed directly in the network. The aim of this issue is to present side by side these di.erent topics, all of which are loosely summarized under quantum structures, to highlight their common aspects, their di.erences, and the progress which resulted from the mutual exchange of results, methods, and knowledge. To guide the reader, we have organized the articles into subsections which follow a rough division into structures in material systems and structures in optical .elds. Nevertheless, in the following introduction we point out connections between the contributions which go beyond these usual criteria, thus highlighting the truly interdisciplinary nature of quantum structures. Much of the progress in atom optics has been generated by the application of concepts from wave optics to matter waves. An example is the contribution by Franke-Arnold et al. The authors investigate the coherence properties of two trapped cold atoms using concepts developed in wave optics. Nevertheless, novel features appear in this system due to the quantum statistics - as atoms may be bosons or fermions - and due to interactions. Matter waves find a spectacular manifestation in Bose-Einstein condensates (BECs) of cold dilute atomic gases. Several concepts of wave optics, like the laser, have been discussed in relation to BECs, and the .eld of atom optics with BECs is rapidly developing. The similarity between the theoretical description of a weakly interacting BEC with that of a non-linear optical system has motivated a series of experiments that led to the observation of, e.g., solitons, vortices and vortex crystallization in matter waves. In this context, the paper by Josopait et al. describes the dynamics of a Bose-Einstein condensate containing a vortex. The vortex stability is discussed as a function of the interparticle interaction, which can be tuned using Feshbach resonances, and the dynamics of the BEC reflected by an atomic mirror is investigated. Non-linear optics merges with atomic physics also in a relatively new research area which aims at quantum non-linear optics with cold atomic gases. Labeyrie et al. use a dense, laser-cooled atomic gas as a non-linear medium for light propagation, and discuss the conditions for observing optical patterns in the transmitted beam. Pattern formation in non-linear optical media is one of the numerous forms of self-organization that these systems display, including also turbulence and optical solitons. With respects to other physical systems, where these phenomena are commonly observed, optical systems are however special: at optical frequencies thermal .uctuations are negligible and do not hide the presence of quantum .uctuations, even at room temperature. Remarkably, the interplay between non-linearity and quantum noise leads to novel phenomena, including optical patterns driven by quantum noise, quantum images, non-classical spatio-temporal correlations, and spatial quantum entanglement. Quantum images are an example of spatial structures dominated by quantum noise, where the structure is absent at a classical level and only proper correlation functions of quantum fluctuations reveal the presence of a regular spatial order. Hoyuelos et al. describe an example of such an image, which is formed in the cross section of the light emitted by an optical parametric oscillator, close to but below the threshold for a square pattern formation. The optical parametric oscillator is also studied in the paper by Rabbiosi et al. which describes the onset of a spatial structure consisting of arrays of localized peaks (cavity solitons) in the transverse cross section of the signal beam. This represents an example of a "disorder to order" transition mediated by quantum noise, where the ordered arrays of solitons are selected among the many possible stable states, only thanks to the presence of quantum noise. As the study of the dynamics of quantum .uctuations in spatially extended systems is a nontraditional subject in quantum optics, alternative techniques of theoretical analysis are needed. The paper by Zambrini et al. proposes an approach based on the use of phase-space representations, in particular of the Q-function with its associated nonlinear Langevin equations. This method provides a full description of the transition from a quantum image to a classical structure through a modulation instability. The Q-representation is also used in a different physical system, the dynamics of the electrons in a driven Helium atom, in the paper by Schlagheck and Buchleitner. Here the authors investigate the quantum manifestations of order and disorder in the motion of the electrons, identifying correspondences between features of the classical phase space and the quantum dynamics. In optical patterns the structure and stability are critically determined by the type of non-linearity of the medium where light propagates, and by the cavity geometry. In atom optics, spatial atomic patterns can be created by light potentials, in particular by arrangements of suitably polarized laser beams which form an optical lattice. The atoms experience mechanical forces arising from the gradient of the light potential. Depending on the tuning of the lasers with respect to the driven atomic transition, these light forces can have a strong or negligible dissipative component, leading to incoherent or coherent motional dynamics. Atomic motion in optical lattices is experimentally investigated in the contributions by Carminati et al. and Jersblad et al. The first article investigates motion-induced resonances in a three-dimensional optical lattice which are observed through pumpprobe laser spectroscopy. The latter contribution studies the effect of the lattice geometry on the atomic steady-state by measuring velocity distributions. The creation of more complex light structures is the subject of the paper by Ellmann et al., where the realization of a double optical lattice is discussed. Such lattices may open up the possibility of coherent manipulation of the atoms in the individual potential wells. An alternative way to structure atoms spatially is discussed by Grabowski and Pfau: here, a regular arrangement of magnetic and magneto-optical traps for ultracold atoms above a surface is described and experimentally observed, where the lattice con.guration is determined by the direction of currents in wire segments beneath the surface. In a different physical systems, semiconductor quantum dots, Jacak et al. study the coupling of arti.cial atoms with the collective excitations of the bulk material in which they are embedded, and investigate coherent and incoherent effects due to this interaction. The presence of correlations at the quantum level leads naturally to the issue of entanglement. This is an exclusive feature of the quantum world, which represents a valuable resource for quantum information processing and for high-precision measurements. The de.nition and criteria for measuring entanglement have been traditionally formulated within the Hilbert-space formalism (the quantum state formalism). However, quantum structures are intrinsically multi-mode systems, for which the Hilbert-space approach is often unpractical and cumbersome. More appealing are the "classical looking" phase space descriptions, where it is hence of great importance to reformulate concepts such as entanglement or Bell inequalities. The paper by Santos addresses the general problem of characterizing the entanglement properties of an electromagnetic field in the language of Q-representation. Entanglement involving the spatial modes of the electromagnetic field carrying orbital angular momentum provides new degrees of freedom and could play an important role in the field of quantum information, since such non-classical states enable the possibility of multichannel communications. The paper by Barbosa discusses quantum states of twin photons produced by parametric down-conversion and entangled in polarization and orbital angular momentum. The issue of entanglement is intrinsically connected to decoherence, and to the transition from the quantum to the classical world. In particular, massive systems are characterized by strong interactions with the environment, and at room temperature they usually exhibit classical behaviour. In this context, the paper by Karlsson discusses the decay of quantum correlations of protons and positive muons in condensed matter, a system characterized by strong coupling to the environment, and proposes experiments where such quantum correlations could be measured. Mancini et al. investigate macroscopic manifestations of quantum features, presenting a proposal for entangling the macroscopic oscillation modes of two cavity mirrors by coupling them to an optical cavity mode. This kind of continuous-variable quantum entanglement may find applications in highprecision measurements, like in atomic force microscopy or gravity wave detection. The question of entanglement for high-precision measurements is also addressed by the paper of Yurtsever et al. which discusses entanglement between matter waves, and proposes the use of entangled atom pairs for a highly sensitive quantum gravity gradiometer. Besides their fundamental interest as a manifestation of quantum .uctuations, spatial quantum correlations in optical beams find their most natural and promising applications in the field of image processing and, more in general, of parallel processing of information. This has opened a new chapter of quantum optics that has been given the name "quantum imaging". In this context, one of the .rst achievements have been the so-called entangled two-photon imaging experiments. This is a technique that exploits the quantum entanglement of a two-photon state to retrieve information about a remote object. In the typical set-up, one photon out of a pair produced by spontaneous parametric down-conversion is used to probe an object, while the other provides a reference. The image of the object emerges in the coincidence counting rate registered as a function of the second photon position. The paper by Shih offers an extensive review of fundamental aspects linked to the entangled two-photon imaging phenomena. It illustrates how quantum imaging techniques may improve classical spatial resolution and presents some of their potential applications for lithography and other microsystem fabrication technologies. A different view on the problem is offered by the paper of Tan et al., which reformulates the two-photon quantum imaging theory from the point of view of retrodictive quantum theory. Since long, quantum noise has been known to represent a limit in high-precision optical measurements. In this context, the contribution by Eschner discusses a single trapped atom probing an optical field and shows that the quantum noise in the atomic motion poses the ultimate limit to the achievable resolution. Recently, it was recognized that quantum noise affects also our ability to resolve an optical image or to detect a small displacement of an optical beam. Properly synthesized multi-mode quantum states are able to circumvent the quantum noise limit and to improve our resolution capabilities in measuring beam displacements. The paper by Barnett et al. shows the similarities between longitudinal phase shifts and transverse beam displacements measurements. Like in interferometry, the sensitivity in the transverse displacement measurement is ultimately limited by the quantum nature of light and can be improved by the use of specific non classical states. The problem of realizing a multi-mode squeezed state is addressed by the paper of Petsas et al. It discusses a realistic implementation of parametric down-conversion in a confocal cavity, able to produce a significant amount of squeezing in small portions of the signal beam cross section. Quantum imaging with macroscopic light beams is a rather new subject of investigation, which represents a non-trivial challenge from the point of view of experimental implementations. One of the main problems is posed by detectors, which should be able to resolve the spatial features of the detected beam with a sensitivity in the photon number measurement beyond the shot noise level. The calibrated CCD camera developed by Jiang et al. makes it possible to get rid of electronic noise or spatial inhomogeneities, a.ecting most of the spatially resolved detectors, and allows the retrieval of spatial shot noise in its full dynamic range. We hope that this special issue helps stimulating further collaborations and fruitful scientific exchange between and beyond the presented fields. We would like to thank the authors for their contributions and the referees for their time and their thoroughness. Our sincerest thanks go to Solange Guéhot in the EPJ D editorial office for very efficiently taking care of all administrative matters. Jürgen Eschner, Institut für Experimentalphysik, Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria Alessandra Gatti, Istituto Nazionale per la Fisica della Materia, Unitá di Como, Via Valleggio 11, 22100 Como, Italy Agnàs Maītre, Laboratoire Kastler-Brossel, Université Pierre et Marie Curie, 4 place Jussieu, 75252 Paris Cedex 05, France Giovanna Morigi, Abteilung Quantenphysik, Universitát Ulm, Albert-Einstein Allee 11, 89069 Ulm, Germany

Synthetic-lattice enabled all-optical devices based on orbital angular momentum of light

PubMed Central

Luo, Xi-Wang; Zhou, Xingxiang; Xu, Jin-Shi; Li, Chuan-Feng; Guo, Guang-Can; Zhang, Chuanwei; Zhou, Zheng-Wei

2017-01-01

All-optical photonic devices are crucial for many important photonic technologies and applications, ranging from optical communication to quantum information processing. Conventional design of all-optical devices is based on photon propagation and interference in real space, which may rely on large numbers of optical elements, and the requirement of precise control makes this approach challenging. Here we propose an unconventional route for engineering all-optical devices using the photon’s internal degrees of freedom, which form photonic crystals in such synthetic dimensions for photon propagation and interference. We demonstrate this design concept by showing how important optical devices such as quantum memory and optical filters can be realized using synthetic orbital angular momentum (OAM) lattices in degenerate cavities. The design route utilizing synthetic photonic lattices may significantly reduce the requirement for numerous optical elements and their fine tuning in conventional design, paving the way for realistic all-optical photonic devices with novel functionalities. PMID:28706215

Quantum walks and wavepacket dynamics on a lattice with twisted photons.

PubMed

Cardano, Filippo; Massa, Francesco; Qassim, Hammam; Karimi, Ebrahim; Slussarenko, Sergei; Paparo, Domenico; de Lisio, Corrado; Sciarrino, Fabio; Santamato, Enrico; Boyd, Robert W; Marrucci, Lorenzo

2015-03-01

The "quantum walk" has emerged recently as a paradigmatic process for the dynamic simulation of complex quantum systems, entanglement production and quantum computation. Hitherto, photonic implementations of quantum walks have mainly been based on multipath interferometric schemes in real space. We report the experimental realization of a discrete quantum walk taking place in the orbital angular momentum space of light, both for a single photon and for two simultaneous photons. In contrast to previous implementations, the whole process develops in a single light beam, with no need of interferometers; it requires optical resources scaling linearly with the number of steps; and it allows flexible control of input and output superposition states. Exploiting the latter property, we explored the system band structure in momentum space and the associated spin-orbit topological features by simulating the quantum dynamics of Gaussian wavepackets. Our demonstration introduces a novel versatile photonic platform for quantum simulations.

Quantum walks and wavepacket dynamics on a lattice with twisted photons

PubMed Central

Cardano, Filippo; Massa, Francesco; Qassim, Hammam; Karimi, Ebrahim; Slussarenko, Sergei; Paparo, Domenico; de Lisio, Corrado; Sciarrino, Fabio; Santamato, Enrico; Boyd, Robert W.; Marrucci, Lorenzo

2015-01-01

The “quantum walk” has emerged recently as a paradigmatic process for the dynamic simulation of complex quantum systems, entanglement production and quantum computation. Hitherto, photonic implementations of quantum walks have mainly been based on multipath interferometric schemes in real space. We report the experimental realization of a discrete quantum walk taking place in the orbital angular momentum space of light, both for a single photon and for two simultaneous photons. In contrast to previous implementations, the whole process develops in a single light beam, with no need of interferometers; it requires optical resources scaling linearly with the number of steps; and it allows flexible control of input and output superposition states. Exploiting the latter property, we explored the system band structure in momentum space and the associated spin-orbit topological features by simulating the quantum dynamics of Gaussian wavepackets. Our demonstration introduces a novel versatile photonic platform for quantum simulations. PMID:26601157

Fabrication of nanoscale heterostructures comprised of graphene-encapsulated gold nanoparticles and semiconducting quantum dots for photocatalysis.

PubMed

Li, Yuan; Chopra, Nitin

2015-05-21

Patterned growth of multilayer graphene shell encapsulated gold nanoparticles (GNPs) and their covalent linking with inorganic quantum dots are demonstrated. GNPs were grown using a xylene chemical vapor deposition process, where the surface oxidized gold nanoparticles catalyze the multilayer graphene shell growth in a single step process. The graphene shell encapsulating gold nanoparticles could be further functionalized with carboxylic groups, which were covalently linked to amine-terminated quantum dots resulting in GNP-quantum dot heterostructures. The compositions, morphologies, crystallinity, and surface functionalization of GNPs and their heterostructures with quantum dots were evaluated using microscopic, spectroscopic, and analytical methods. Furthermore, optical properties of the derived architectures were studied using both experimental methods and simulations. Finally, GNP-quantum dot heterostructures were studied for photocatalytic degradation of phenol.

Upconversion-based receivers for quantum hacking-resistant quantum key distribution

NASA Astrophysics Data System (ADS)

Jain, Nitin; Kanter, Gregory S.

2016-07-01

We propose a novel upconversion (sum frequency generation)-based quantum-optical system design that can be employed as a receiver (Bob) in practical quantum key distribution systems. The pump governing the upconversion process is produced and utilized inside the physical receiver, making its access or control unrealistic for an external adversary (Eve). This pump facilitates several properties which permit Bob to define and control the modes that can participate in the quantum measurement. Furthermore, by manipulating and monitoring the characteristics of the pump pulses, Bob can detect a wide range of quantum hacking attacks launched by Eve.

Memory for light as a quantum process.

PubMed

Lobino, M; Kupchak, C; Figueroa, E; Lvovsky, A I

2009-05-22

We report complete characterization of an optical memory based on electromagnetically induced transparency. We recover the superoperator associated with the memory, under two different working conditions, by means of a quantum process tomography technique that involves storage of coherent states and their characterization upon retrieval. In this way, we can predict the quantum state retrieved from the memory for any input, for example, the squeezed vacuum or the Fock state. We employ the acquired superoperator to verify the nonclassicality benchmark for the storage of a Gaussian distributed set of coherent states.

PREFACE: Quantum information processing

NASA Astrophysics Data System (ADS)

Briggs, Andrew; Ferry, David; Stoneham, Marshall

2006-05-01

Microelectronics and the classical information technologies transformed the physics of semiconductors. Photonics has given optical materials a new direction. Quantum information technologies, we believe, will have immense impact on condensed matter physics. The novel systems of quantum information processing need to be designed and made. Their behaviours must be manipulated in ways that are intrinsically quantal and generally nanoscale. Both in this special issue and in previous issues (see e.g., Spiller T P and Munro W J 2006 J. Phys.: Condens. Matter 18 V1-10) we see the emergence of new ideas that link the fundamentals of science to the pragmatism of market-led industry. We hope these papers will be followed by many others on quantum information processing in the Journal of Physics: Condensed Matter.

Remnants of semiclassical bistability in the few-photon regime of cavity QED.

PubMed

Kerckhoff, Joseph; Armen, Michael A; Mabuchi, Hideo

2011-11-21

Broadband homodyne detection of the light transmitted by a Fabry-Perot cavity containing a strongly-coupled (133)Cs atom is used to probe the dynamic optical response in a regime where semiclassical theory predicts bistability but strong quantum corrections should apply. While quantum fluctuations destabilize true equilibrium bistability, our observations confirm the existence of metastable states with finite lifetimes and a hysteretic response is apparent when the optical drive is modulated on comparable timescales. Our experiment elucidates remnant semiclassical behavior in the attojoule (~10 photon) regime of single-atom cavity QED, of potential significance for ultra-low power photonic signal processing. © 2011 Optical Society of America

All-optical control and super-resolution imaging of quantum emitters in layered materials.

PubMed

Kianinia, Mehran; Bradac, Carlo; Sontheimer, Bernd; Wang, Fan; Tran, Toan Trong; Nguyen, Minh; Kim, Sejeong; Xu, Zai-Quan; Jin, Dayong; Schell, Andreas W; Lobo, Charlene J; Aharonovich, Igor; Toth, Milos

2018-02-28

Layered van der Waals materials are emerging as compelling two-dimensional platforms for nanophotonics, polaritonics, valleytronics and spintronics, and have the potential to transform applications in sensing, imaging and quantum information processing. Among these, hexagonal boron nitride (hBN) is known to host ultra-bright, room-temperature quantum emitters, whose nature is yet to be fully understood. Here we present a set of measurements that give unique insight into the photophysical properties and level structure of hBN quantum emitters. Specifically, we report the existence of a class of hBN quantum emitters with a fast-decaying intermediate and a long-lived metastable state accessible from the first excited electronic state. Furthermore, by means of a two-laser repumping scheme, we show an enhanced photoluminescence and emission intensity, which can be utilized to realize a new modality of far-field super-resolution imaging. Our findings expand current understanding of quantum emitters in hBN and show new potential ways of harnessing their nonlinear optical properties in sub-diffraction nanoscopy.

Two-photon absorption and efficient encapsulation of near-infrared-emitting CdSexTe1-x quantum dots

NASA Astrophysics Data System (ADS)

Szeremeta, Janusz; Lamch, Lukasz; Wawrzynczyk, Dominika; Wilk, Kazimiera A.; Samoc, Marek; Nyk, Marcin

2015-07-01

Hydrophobic CdSexTe1-x quantum dots with near infrared emission in the 700-750 nm range were synthesized by a wet chemistry technique. Their nonlinear optical properties were studied using Z-scan technique with a tunable femtosecond laser system. The peak value of the two-photon absorption cross section was found to be ∼2400 GM at 1400 nm. To demonstrate a possible way of utilizing the CdSexTe1-x quantum dots in aqueous environment we describe here a convenient method of preparation of Brij 58® micellar systems loaded with the quantum dots. The obtained nanoconstructs were characterized using optical spectroscopy, TEM and DLS. The micelles colloidal stability, and the influence of the encapsulation process on the spectroscopic properties of the quantum dots are discussed. In particular, we have observed a 60 nm blue-shift of the emission maxima upon loading quantum dots inside the micelles.

Entanglement of Ince-Gauss Modes of Photons

NASA Astrophysics Data System (ADS)

Krenn, Mario; Fickler, Robert; Plick, William; Lapkiewicz, Radek; Ramelow, Sven; Zeilinger, Anton

2012-02-01

Ince-Gauss modes are solutions of the paraxial wave equation in elliptical coordinates [1]. They are natural generalizations both of Laguerre-Gauss and of Hermite-Gauss modes, which have been used extensively in quantum optics and quantum information processing over the last decade [2]. Ince-Gauss modes are described by one additional real parameter -- ellipticity. For each value of ellipticity, a discrete infinite-dimensional Hilbert space exists. This conceptually new degree of freedom could open up exciting possibilities for higher-dimensional quantum optical experiments. We present the first entanglement of non-trivial Ince-Gauss Modes. In our setup, we take advantage of a spontaneous parametric down-conversion process in a non-linear crystal to create entangled photon pairs. Spatial light modulators (SLMs) are used as analyzers. [1] Miguel A. Bandres and Julio C. Guti'errez-Vega ``Ince Gaussian beams", Optics Letters, Vol. 29, Issue 2, 144-146 (2004) [2] Adetunmise C. Dada, Jonathan Leach, Gerald S. Buller, Miles J. Padgett, and Erika Andersson, ``Experimental high-dimensional two-photon entanglement and violations of generalized Bell inequalities", Nature Physics 7, 677-680 (2011)

Teleportation-based realization of an optical quantum two-qubit entangling gate

PubMed Central

Gao, Wei-Bo; Goebel, Alexander M.; Lu, Chao-Yang; Dai, Han-Ning; Wagenknecht, Claudia; Zhang, Qiang; Zhao, Bo; Peng, Cheng-Zhi; Chen, Zeng-Bing; Chen, Yu-Ao; Pan, Jian-Wei

2010-01-01

In recent years, there has been heightened interest in quantum teleportation, which allows for the transfer of unknown quantum states over arbitrary distances. Quantum teleportation not only serves as an essential ingredient in long-distance quantum communication, but also provides enabling technologies for practical quantum computation. Of particular interest is the scheme proposed by D. Gottesman and I. L. Chuang [(1999) Nature 402:390–393], showing that quantum gates can be implemented by teleporting qubits with the help of some special entangled states. Therefore, the construction of a quantum computer can be simply based on some multiparticle entangled states, Bell-state measurements, and single-qubit operations. The feasibility of this scheme relaxes experimental constraints on realizing universal quantum computation. Using two different methods, we demonstrate the smallest nontrivial module in such a scheme—a teleportation-based quantum entangling gate for two different photonic qubits. One uses a high-fidelity six-photon interferometer to realize controlled-NOT gates, and the other uses four-photon hyperentanglement to realize controlled-Phase gates. The results clearly demonstrate the working principles and the entangling capability of the gates. Our experiment represents an important step toward the realization of practical quantum computers and could lead to many further applications in linear optics quantum information processing. PMID:21098305

Teleportation-based realization of an optical quantum two-qubit entangling gate.

PubMed

Gao, Wei-Bo; Goebel, Alexander M; Lu, Chao-Yang; Dai, Han-Ning; Wagenknecht, Claudia; Zhang, Qiang; Zhao, Bo; Peng, Cheng-Zhi; Chen, Zeng-Bing; Chen, Yu-Ao; Pan, Jian-Wei

2010-12-07

In recent years, there has been heightened interest in quantum teleportation, which allows for the transfer of unknown quantum states over arbitrary distances. Quantum teleportation not only serves as an essential ingredient in long-distance quantum communication, but also provides enabling technologies for practical quantum computation. Of particular interest is the scheme proposed by D. Gottesman and I. L. Chuang [(1999) Nature 402:390-393], showing that quantum gates can be implemented by teleporting qubits with the help of some special entangled states. Therefore, the construction of a quantum computer can be simply based on some multiparticle entangled states, Bell-state measurements, and single-qubit operations. The feasibility of this scheme relaxes experimental constraints on realizing universal quantum computation. Using two different methods, we demonstrate the smallest nontrivial module in such a scheme--a teleportation-based quantum entangling gate for two different photonic qubits. One uses a high-fidelity six-photon interferometer to realize controlled-NOT gates, and the other uses four-photon hyperentanglement to realize controlled-Phase gates. The results clearly demonstrate the working principles and the entangling capability of the gates. Our experiment represents an important step toward the realization of practical quantum computers and could lead to many further applications in linear optics quantum information processing.

Continuous-variable quantum computing in optical time-frequency modes using quantum memories.

PubMed

Humphreys, Peter C; Kolthammer, W Steven; Nunn, Joshua; Barbieri, Marco; Datta, Animesh; Walmsley, Ian A

2014-09-26

We develop a scheme for time-frequency encoded continuous-variable cluster-state quantum computing using quantum memories. In particular, we propose a method to produce, manipulate, and measure two-dimensional cluster states in a single spatial mode by exploiting the intrinsic time-frequency selectivity of Raman quantum memories. Time-frequency encoding enables the scheme to be extremely compact, requiring a number of memories that are a linear function of only the number of different frequencies in which the computational state is encoded, independent of its temporal duration. We therefore show that quantum memories can be a powerful component for scalable photonic quantum information processing architectures.

Controlled waveguide coupling for photon emission from colloidal PbS quantum dot using tunable microcavity made of optical polymer and silicon

NASA Astrophysics Data System (ADS)

Nozaka, Takahiro; Mukai, Kohki

2016-04-01

A tunable microcavity device composed of optical polymer and Si with a colloidal quantum dot (QD) is proposed as a single-photon source for planar optical circuit. Cavity size is controlled by electrostatic micromachine behavior with the air bridge structure to tune timing of photon injection into optical waveguide from QD. Three-dimensional positioning of a QD in the cavity structure is available using a nanohole on Si processed by scanning probe microscope lithography. We fabricated the prototype microcavity with PbS-QD-mixed polymenthyl methacrylate on a SOI (semiconductor-on-insulator) substrate to show the tunability of cavity size as the shift of emission peak wavelength of QD ensemble.

Ultralow-light-level all-optical transistor in rubidium vapor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jing, Jietai, E-mail: jtjing@phy.ecnu.edu.cn; Zhou, Zhifan; Liu, Cunjin

2014-04-14

An all-optical transistor (AOT) is a device in which one light beam can efficiently manipulate another. It is the foundational component of an all-optical communication network. An AOT that can operate at ultralow light levels is especially attractive for its potential application in the quantum information field. Here, we demonstrate an AOT driven by a weak light beam with an energy density of 2.5 × 10{sup −5} photons/(λ{sup 2}/2π) (corresponding to 6  yJ/(λ{sup 2}/2π) and about 800 total photons) using the double-Λ four-wave mixing process in hot rubidium vapor. This makes it a promising candidate for ultralow-light-level optical communication and quantum information science.

The Interplay of Quantum Confinement and Hydrogenation in Amorphous Silicon Quantum Dots.

PubMed

Askari, Sadegh; Svrcek, Vladmir; Maguire, Paul; Mariotti, Davide

2015-12-22

Hydrogenation in amorphous silicon quantum dots (QDs) has a dramatic impact on the corresponding optical properties and band energy structure, leading to a quantum-confined composite material with unique characteristics. The synthesis of a-Si:H QDs is demonstrated with an atmospheric-pressure plasma process, which allows for accurate control of a highly chemically reactive non-equilibrium environment with temperatures well below the crystallization temperature of Si QDs. © 2015 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Broadband enhancement of single photon emission and polarization dependent coupling in silicon nitride waveguides.

PubMed

Bisschop, Suzanne; Guille, Antoine; Van Thourhout, Dries; Hens, Zeger; Brainis, Edouard

2015-06-01

Single-photon (SP) sources are important for a number of optical quantum information processing applications. We study the possibility to integrate triggered solid-state SP emitters directly on a photonic chip. A major challenge consists in efficiently extracting their emission into a single guided mode. Using 3D finite-difference time-domain simulations, we investigate the SP emission from dipole-like nanometer-sized inclusions embedded into different silicon nitride (SiNx) photonic nanowire waveguide designs. We elucidate the effect of the geometry on the emission lifetime and the polarization of the emitted SP. The results show that highly efficient and polarized SP sources can be realized using suspended SiNx slot-waveguides. Combining this with the well-established CMOS-compatible processing technology, fully integrated and complex optical circuits for quantum optics experiments can be developed.

Electro-Optic Frequency Beam Splitters and Tritters for High-Fidelity Photonic Quantum Information Processing

DOE PAGES

Lu, Hsuan-Hao; Lukens, Joseph M.; Peters, Nicholas A.; ...

2018-01-18

In this paper, we report the experimental realization of high-fidelity photonic quantum gates for frequency-encoded qubits and qutrits based on electro-optic modulation and Fourier-transform pulse shaping. Our frequency version of the Hadamard gate offers near-unity fidelity (0.99998±0.00003), requires only a single microwave drive tone for near-ideal performance, functions across the entire C band (1530–1570 nm), and can operate concurrently on multiple qubits spaced as tightly as four frequency modes apart, with no observable degradation in the fidelity. For qutrits, we implement a 3×3 extension of the Hadamard gate: the balanced tritter. This tritter—the first ever demonstrated for frequency modes—attains fidelitymore » 0.9989±0.0004. Finally, these gates represent important building blocks toward scalable, high-fidelity quantum information processing based on frequency encoding.« less

Electro-Optic Frequency Beam Splitters and Tritters for High-Fidelity Photonic Quantum Information Processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Hsuan-Hao; Lukens, Joseph M.; Peters, Nicholas A.

In this paper, we report the experimental realization of high-fidelity photonic quantum gates for frequency-encoded qubits and qutrits based on electro-optic modulation and Fourier-transform pulse shaping. Our frequency version of the Hadamard gate offers near-unity fidelity (0.99998±0.00003), requires only a single microwave drive tone for near-ideal performance, functions across the entire C band (1530–1570 nm), and can operate concurrently on multiple qubits spaced as tightly as four frequency modes apart, with no observable degradation in the fidelity. For qutrits, we implement a 3×3 extension of the Hadamard gate: the balanced tritter. This tritter—the first ever demonstrated for frequency modes—attains fidelitymore » 0.9989±0.0004. Finally, these gates represent important building blocks toward scalable, high-fidelity quantum information processing based on frequency encoding.« less

Quantum frequency up-conversion of continuous variable entangled states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Wenyuan; Wang, Ning; Li, Zongyang

We demonstrate experimentally quantum frequency up-conversion of a continuous variable entangled optical field via sum-frequency-generation process. The two-color entangled state initially entangled at 806 and 1518 nm with an amplitude quadrature difference squeezing of 3.2 dB and phase quadrature sum squeezing of 3.1 dB is converted to a new entangled state at 530 and 1518 nm with the amplitude quadrature difference squeezing of 1.7 dB and phase quadrature sum squeezing of 1.8 dB. Our implementation enables the observation of entanglement between two light fields spanning approximately 1.5 octaves in optical frequency. The presented scheme is robust to the excess amplitude and phase noises of the pumpmore » field, making it a practical building block for quantum information processing and communication networks.« less

Biphoton optics

NASA Astrophysics Data System (ADS)

Strekalov, Dmitry Vladimirovich

1997-10-01

The subject of this dissertation is the study of the two- photon entanglement. This phenomenon has been paid a great deal of attention since 1935, when A. Einstein, B. Podolsky and N. Rosen asked their famous question, 'Can quantum-mechanical description of physical reality be considered complete?' An entangled system behavior is inconsistent with many classical concepts. Therefore, the understanding of two-photon entanglement is important for the foundations of quantum theory. A two-photon entangled sate represents a two-photon, or a biphoton, rather than two photons. The concept of biphoton as a single nonlocal quantum object is fundamentally different from the concept of a photon pair, as has been experimentally demonstrated in the present dissertation. Two-photon entanglement gives rise to unusual 'ghost' interference and diffraction, nonlocal geometrical phase, and other quantum phenomena originally studied in the present dissertation. The variety of available results calls for bringing them into a general system which we call Biphoton Optics. This is the main goal of this dissertation. Biphoton optics operate with two-photon wave packets, or with an equivalent concept of advanced wave. We show that in the framework of the advanced wave concept two-photon phenomena can be effectively described in terms of classical optics. Therefore the biphoton optics has the same structure as the classical optics. It includes two- photon geometrical optics, dispersion and frequency beating, polarization effects, interference, diffraction, and geometrical phase. All these two-photon effects are represented by experiments included in this dissertation. Our approach does not make two-photon quantum effects 'classical', however. It should be understood that the advanced wave model operates with counter-propagation in time which does not correspond to any real physical process. Therefore it is just a model, but it is clearly a great advantage to have such a model that is both simple and powerful, in terms of its ability to describe the known results and accurately predict the new ones. Therefore an important step is made in understanding and describing of the quantum phenomena of two-photon entanglement.

Observation of entanglement between a quantum dot spin and a single photon.

PubMed

Gao, W B; Fallahi, P; Togan, E; Miguel-Sanchez, J; Imamoglu, A

2012-11-15

Entanglement has a central role in fundamental tests of quantum mechanics as well as in the burgeoning field of quantum information processing. Particularly in the context of quantum networks and communication, a main challenge is the efficient generation of entanglement between stationary (spin) and propagating (photon) quantum bits. Here we report the observation of quantum entanglement between a semiconductor quantum dot spin and the colour of a propagating optical photon. The demonstration of entanglement relies on the use of fast, single-photon detection, which allows us to project the photon into a superposition of red and blue frequency components. Our results extend the previous demonstrations of single-spin/single-photon entanglement in trapped ions, neutral atoms and nitrogen-vacancy centres to the domain of artificial atoms in semiconductor nanostructures that allow for on-chip integration of electronic and photonic elements. As a result of its fast optical transitions and favourable selection rules, the scheme we implement could in principle generate nearly deterministic entangled spin-photon pairs at a rate determined ultimately by the high spontaneous emission rate. Our observation constitutes a first step towards implementation of a quantum network with nodes consisting of semiconductor spin quantum bits.

Accurate and agile digital control of optical phase, amplitude and frequency for coherent atomic manipulation of atomic systems.

PubMed

Thom, Joseph; Wilpers, Guido; Riis, Erling; Sinclair, Alastair G

2013-08-12

We demonstrate a system for fast and agile digital control of laser phase, amplitude and frequency for applications in coherent atomic systems. The full versatility of a direct digital synthesis radiofrequency source is faithfully transferred to laser radiation via acousto-optic modulation. Optical beatnotes are used to measure phase steps up to 2π, which are accurately implemented with a resolution of ≤ 10 mrad. By linearizing the optical modulation process, amplitude-shaped pulses of durations ranging from 500 ns to 500 ms, in excellent agreement with the programmed functional form, are demonstrated. Pulse durations are limited only by the 30 ns rise time of the modulation process, and a measured extinction ratio of > 5 × 10(11) is achieved. The system presented here was developed specifically for controlling the quantum state of trapped ions with sequences of multiple laser pulses, including composite and bichromatic pulses. The demonstrated techniques are widely applicable to other atomic systems ranging across quantum information processing, frequency metrology, atom interferometry, and single-photon generation.

Generalized Hofmann quantum process fidelity bounds for quantum filters

NASA Astrophysics Data System (ADS)

Sedlák, Michal; Fiurášek, Jaromír

2016-04-01

We propose and investigate bounds on the quantum process fidelity of quantum filters, i.e., probabilistic quantum operations represented by a single Kraus operator K . These bounds generalize the Hofmann bounds on the quantum process fidelity of unitary operations [H. F. Hofmann, Phys. Rev. Lett. 94, 160504 (2005), 10.1103/PhysRevLett.94.160504] and are based on probing the quantum filter with pure states forming two mutually unbiased bases. Determination of these bounds therefore requires far fewer measurements than full quantum process tomography. We find that it is particularly suitable to construct one of the probe bases from the right eigenstates of K , because in this case the bounds are tight in the sense that if the actual filter coincides with the ideal one, then both the lower and the upper bounds are equal to 1. We theoretically investigate the application of these bounds to a two-qubit optical quantum filter formed by the interference of two photons on a partially polarizing beam splitter. For an experimentally convenient choice of factorized input states and measurements we study the tightness of the bounds. We show that more stringent bounds can be obtained by more sophisticated processing of the data using convex optimization and we compare our methods for different choices of the input probe states.

Modeling techniques for quantum cascade lasers

NASA Astrophysics Data System (ADS)

Jirauschek, Christian; Kubis, Tillmann

2014-03-01

Quantum cascade lasers are unipolar semiconductor lasers covering a wide range of the infrared and terahertz spectrum. Lasing action is achieved by using optical intersubband transitions between quantized states in specifically designed multiple-quantum-well heterostructures. A systematic improvement of quantum cascade lasers with respect to operating temperature, efficiency, and spectral range requires detailed modeling of the underlying physical processes in these structures. Moreover, the quantum cascade laser constitutes a versatile model device for the development and improvement of simulation techniques in nano- and optoelectronics. This review provides a comprehensive survey and discussion of the modeling techniques used for the simulation of quantum cascade lasers. The main focus is on the modeling of carrier transport in the nanostructured gain medium, while the simulation of the optical cavity is covered at a more basic level. Specifically, the transfer matrix and finite difference methods for solving the one-dimensional Schrödinger equation and Schrödinger-Poisson system are discussed, providing the quantized states in the multiple-quantum-well active region. The modeling of the optical cavity is covered with a focus on basic waveguide resonator structures. Furthermore, various carrier transport simulation methods are discussed, ranging from basic empirical approaches to advanced self-consistent techniques. The methods include empirical rate equation and related Maxwell-Bloch equation approaches, self-consistent rate equation and ensemble Monte Carlo methods, as well as quantum transport approaches, in particular the density matrix and non-equilibrium Green's function formalism. The derived scattering rates and self-energies are generally valid for n-type devices based on one-dimensional quantum confinement, such as quantum well structures.

Modeling techniques for quantum cascade lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jirauschek, Christian; Kubis, Tillmann

2014-03-15

Quantum cascade lasers are unipolar semiconductor lasers covering a wide range of the infrared and terahertz spectrum. Lasing action is achieved by using optical intersubband transitions between quantized states in specifically designed multiple-quantum-well heterostructures. A systematic improvement of quantum cascade lasers with respect to operating temperature, efficiency, and spectral range requires detailed modeling of the underlying physical processes in these structures. Moreover, the quantum cascade laser constitutes a versatile model device for the development and improvement of simulation techniques in nano- and optoelectronics. This review provides a comprehensive survey and discussion of the modeling techniques used for the simulation ofmore » quantum cascade lasers. The main focus is on the modeling of carrier transport in the nanostructured gain medium, while the simulation of the optical cavity is covered at a more basic level. Specifically, the transfer matrix and finite difference methods for solving the one-dimensional Schrödinger equation and Schrödinger-Poisson system are discussed, providing the quantized states in the multiple-quantum-well active region. The modeling of the optical cavity is covered with a focus on basic waveguide resonator structures. Furthermore, various carrier transport simulation methods are discussed, ranging from basic empirical approaches to advanced self-consistent techniques. The methods include empirical rate equation and related Maxwell-Bloch equation approaches, self-consistent rate equation and ensemble Monte Carlo methods, as well as quantum transport approaches, in particular the density matrix and non-equilibrium Green's function formalism. The derived scattering rates and self-energies are generally valid for n-type devices based on one-dimensional quantum confinement, such as quantum well structures.« less

Quantum Optomechanics with Silicon Nanostructures

NASA Astrophysics Data System (ADS)

Safavi-Naeini, Amir H.

Mechanical resonators are the most basic and ubiquitous physical systems known. In on-chip form, they are used to process high frequency signals in every cell phone, television, and laptop. They have also been in the last few decades in different shapes and forms, a critical part of progress in quantum information sciences with kilogram scale mirrors for gravitational wave detection measuring motion at its quantum limits, and the motion of single ions being used to link qubits for quantum computation. Optomechanics is a field primarily concerned with coupling light to the motion of mechanical structures. This thesis contains descriptions of recent work with mechanical systems in the megahertz to gigahertz frequency range, formed by nanofabricating novel photonic/phononic structures on a silicon chip. These structures are designed to have both optical and mechanical resonances, and laser light is used to address and manipulate their motional degrees of freedom through radiation pressure forces. We laser cool these mechanical resonators to their ground states, and observe for the first time the quantum zero-point motion of a nanomechanical resonator. Conversely, we show that engineered mechanical resonances drastically modify the optical response of our structures, creating large effective optical nonlinearities not present in bulk silicon. We experimentally demonstrate aspects of these nonlinearities by proposing and observing ``electromagnetically induced transparency'' and light slowed down to 6 m/s, as well as wavelength conversion, and generation of nonclassical optical radiation. Finally, the application of optomechanics to longstanding problems in quantum and classical communications are proposed and investigated.

Emerging Connections: Quantum & Classical Optics Incubator Program Book

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lesky, Marcia

The Emerging Connections: Quantum & Classical Optics Incubator was a scientific meeting held in Washington, DC on 6-8 November 2016. This Incubator provided unique and focused experiences and valuable opportunities to discuss advances, challenges and opportunities regarding this important area of research. Quantum optics and classical optics have coexisted for nearly a century as two distinct, but consistent descriptions of light in their respective domains. Recently, a number of detailed examinations of the structure of classical light beams have revealed that effects widely thought to be solely quantum in origin also have a place in classical optics. These new quantum-classicalmore » connections are informing classical optics in meaningful ways specifically by expanding understanding of optical coherence. Simultaneously, relationships discovered with classical light beams now also serve as a vehicle to illuminate concepts that no longer solely belong to the quantum realm. Interference, polarization, coherence, complementarity and entanglement are a partial list of elementary notions that now appear to belong to both quantum and classical optics. The goal of this meeting was to bring emerging quantum-classical links into wider view and to indicate directions in which forthcoming and future work would promote discussion and lead to a more unified understanding of optics.« less

Non-Gaussian operations on bosonic modes of light: Photon-added Gaussian channels

NASA Astrophysics Data System (ADS)

Sabapathy, Krishna Kumar; Winter, Andreas

2017-06-01

We present a framework for studying bosonic non-Gaussian channels of continuous-variable systems. Our emphasis is on a class of channels that we call photon-added Gaussian channels, which are experimentally viable with current quantum-optical technologies. A strong motivation for considering these channels is the fact that it is compulsory to go beyond the Gaussian domain for numerous tasks in continuous-variable quantum information processing such as entanglement distillation from Gaussian states and universal quantum computation. The single-mode photon-added channels we consider are obtained by using two-mode beam splitters and squeezing operators with photon addition applied to the ancilla ports giving rise to families of non-Gaussian channels. For each such channel, we derive its operator-sum representation, indispensable in the present context. We observe that these channels are Fock preserving (coherence nongenerating). We then report two examples of activation using our scheme of photon addition, that of quantum-optical nonclassicality at outputs of channels that would otherwise output only classical states and of both the quantum and private communication capacities, hinting at far-reaching applications for quantum-optical communication. Further, we see that noisy Gaussian channels can be expressed as a convex mixture of these non-Gaussian channels. We also present other physical and information-theoretic properties of these channels.

Surface Plasmon Enhanced Sensitive Detection for Possible Signature of Majorana Fermions via a Hybrid Semiconductor Quantum Dot-Metal Nanoparticle System

PubMed Central

Chen, Hua-Jun; Zhu, Ka-Di

2015-01-01

In the present work, we theoretically propose an optical scheme to detect the possible signature of Majorana fermions via the optical pump-probe spectroscopy, which is very different from the current tunneling measurement based on electrical methods. The scheme consists of a metal nanoparticle and a semiconductor quantum dot coupled to a hybrid semiconductor/superconductor heterostructures. The results show that the probe absorption spectrum of the quantum dot presents a distinct splitting due to the existence of Majorana fermions. Owing to surface plasmon enhanced effect, this splitting will be more obvious, which makes Majorana fermions more easy to be detectable. The technique proposed here open the door for new applications ranging from robust manipulation of Majorana fermions to quantum information processing based on Majorana fermions. PMID:26310929

Quantum interference in heterogeneous superconducting-photonic circuits on a silicon chip.

PubMed

Schuck, C; Guo, X; Fan, L; Ma, X; Poot, M; Tang, H X

2016-01-21

Quantum information processing holds great promise for communicating and computing data efficiently. However, scaling current photonic implementation approaches to larger system size remains an outstanding challenge for realizing disruptive quantum technology. Two main ingredients of quantum information processors are quantum interference and single-photon detectors. Here we develop a hybrid superconducting-photonic circuit system to show how these elements can be combined in a scalable fashion on a silicon chip. We demonstrate the suitability of this approach for integrated quantum optics by interfering and detecting photon pairs directly on the chip with waveguide-coupled single-photon detectors. Using a directional coupler implemented with silicon nitride nanophotonic waveguides, we observe 97% interference visibility when measuring photon statistics with two monolithically integrated superconducting single-photon detectors. The photonic circuit and detector fabrication processes are compatible with standard semiconductor thin-film technology, making it possible to implement more complex and larger scale quantum photonic circuits on silicon chips.

Laser writing of coherent colour centres in diamond

NASA Astrophysics Data System (ADS)

Chen, Yu-Chen; Salter, Patrick S.; Knauer, Sebastian; Weng, Laiyi; Frangeskou, Angelo C.; Stephen, Colin J.; Ishmael, Shazeaa N.; Dolan, Philip R.; Johnson, Sam; Green, Ben L.; Morley, Gavin W.; Newton, Mark E.; Rarity, John G.; Booth, Martin J.; Smith, Jason M.

2017-02-01

Optically active point defects in crystals have gained widespread attention as photonic systems that could be applied in quantum information technologies. However, challenges remain in the placing of individual defects at desired locations, an essential element of device fabrication. Here we report the controlled generation of single negatively charged nitrogen-vacancy (NV-) centres in diamond using laser writing. Aberration correction in the writing optics allows precise positioning of the vacancies within the diamond crystal, and subsequent annealing produces single NV- centres with a probability of success of up to 45 ± 15%, located within about 200 nm of the desired position in the transverse plane. Selected NV- centres display stable, coherent optical transitions at cryogenic temperatures, a prerequisite for the creation of distributed quantum networks of solid-state qubits. The results illustrate the potential of laser writing as a new tool for defect engineering in quantum technologies, and extend laser processing to the single-defect domain.

Noise and correlations in a microwave-mechanical-optical transducer

NASA Astrophysics Data System (ADS)

Higginbotham, Andrew P.; Burns, Peter S.; Peterson, Robert W.; Urmey, Maxwell D.; Kampel, Nir S.; Menke, Timothy; Cicak, Katarina; Simmonds, Raymond W.; Regal, Cindy A.; Lehnert, Konrad W.

Viewed as resources for quantum information processing, microwave and optical fields offer complementary strengths. We simultaneously couple one mode of a micromechanical oscillator to a resonant microwave circuit and a high-finesse optical cavity. In previous work, this system was operated as a classical converter between microwave and optical signals at 4 K, operating with 10% efficiency and 1500 photons of added noise. To improve noise performance, we now operate the converter at 0.1 K. We have observed order-of-magnitude improvement in noise performance, and quantified effects from undesired interactions between the laser and superconducting circuit. Correlations between the microwave and optical fields have also been investigated, serving as a precursor to upcoming quantum operation. We acknowledge support from AFOSR MURI Grant FA9550-15-1-0015 and PFC National Science Foundation Grant 1125844.

Roadmap on quantum optical systems

NASA Astrophysics Data System (ADS)

Dumke, Rainer; Lu, Zehuang; Close, John; Robins, Nick; Weis, Antoine; Mukherjee, Manas; Birkl, Gerhard; Hufnagel, Christoph; Amico, Luigi; Boshier, Malcolm G.; Dieckmann, Kai; Li, Wenhui; Killian, Thomas C.

2016-09-01

This roadmap bundles fast developing topics in experimental optical quantum sciences, addressing current challenges as well as potential advances in future research. We have focused on three main areas: quantum assisted high precision measurements, quantum information/simulation, and quantum gases. Quantum assisted high precision measurements are discussed in the first three sections, which review optical clocks, atom interferometry, and optical magnetometry. These fields are already successfully utilized in various applied areas. We will discuss approaches to extend this impact even further. In the quantum information/simulation section, we start with the traditionally successful employed systems based on neutral atoms and ions. In addition the marvelous demonstrations of systems suitable for quantum information is not progressing, unsolved challenges remain and will be discussed. We will also review, as an alternative approach, the utilization of hybrid quantum systems based on superconducting quantum devices and ultracold atoms. Novel developments in atomtronics promise unique access in exploring solid-state systems with ultracold gases and are investigated in depth. The sections discussing the continuously fast-developing quantum gases include a review on dipolar heteronuclear diatomic gases, Rydberg gases, and ultracold plasma. Overall, we have accomplished a roadmap of selected areas undergoing rapid progress in quantum optics, highlighting current advances and future challenges. These exciting developments and vast advances will shape the field of quantum optics in the future.

Quantum Optics in Diamond Nanophotonic Chips

DTIC Science & Technology

2014-07-01

quantum cryptography , quantum teleportation, quantum computation. Springer-Verlag, London, UK, 2000. 8 [3] J. I. Cirac, P. Zoller, H. J. Kimble, and...AFRL-OSR-VA-TR-2014-0188 Quantum Optics in Diamond Nanophotonic Chips Dirk Englund THE TRUSTEES OF COLUMBIA UNIVERSITY IN THE CITY OF NEW YORK INC...Progress Report Program Manager: Dr. Gernot Pomrenke Quantum Optics in Diamond Nanophotonic Chips AFOSR Directorate: Physics and Electronics Research

Engineering two-photon high-dimensional states through quantum interference

PubMed Central

Zhang, Yingwen; Roux, Filippus S.; Konrad, Thomas; Agnew, Megan; Leach, Jonathan; Forbes, Andrew

2016-01-01

Many protocols in quantum science, for example, linear optical quantum computing, require access to large-scale entangled quantum states. Such systems can be realized through many-particle qubits, but this approach often suffers from scalability problems. An alternative strategy is to consider a lesser number of particles that exist in high-dimensional states. The spatial modes of light are one such candidate that provides access to high-dimensional quantum states, and thus they increase the storage and processing potential of quantum information systems. We demonstrate the controlled engineering of two-photon high-dimensional states entangled in their orbital angular momentum through Hong-Ou-Mandel interference. We prepare a large range of high-dimensional entangled states and implement precise quantum state filtering. We characterize the full quantum state before and after the filter, and are thus able to determine that only the antisymmetric component of the initial state remains. This work paves the way for high-dimensional processing and communication of multiphoton quantum states, for example, in teleportation beyond qubits. PMID:26933685

Continuous-wave infrared optical gain and amplified spontaneous emission at ultralow threshold by colloidal HgTe quantum dots.

PubMed

Geiregat, Pieter; Houtepen, Arjan J; Sagar, Laxmi Kishore; Infante, Ivan; Zapata, Felipe; Grigel, Valeriia; Allan, Guy; Delerue, Christophe; Van Thourhout, Dries; Hens, Zeger

2018-01-01

Colloidal quantum dots (QDs) raise more and more interest as solution-processable and tunable optical gain materials. However, especially for infrared active QDs, optical gain remains inefficient. Since stimulated emission involves multifold degenerate band-edge states, population inversion can be attained only at high pump power and must compete with efficient multi-exciton recombination. Here, we show that mercury telluride (HgTe) QDs exhibit size-tunable stimulated emission throughout the near-infrared telecom window at thresholds unmatched by any QD studied before. We attribute this unique behaviour to surface-localized states in the bandgap that turn HgTe QDs into 4-level systems. The resulting long-lived population inversion induces amplified spontaneous emission under continuous-wave optical pumping at power levels compatible with solar irradiation and direct current electrical pumping. These results introduce an alternative approach for low-threshold QD-based gain media based on intentional trap states that paves the way for solution-processed infrared QD lasers and amplifiers.

Continuous-wave infrared optical gain and amplified spontaneous emission at ultralow threshold by colloidal HgTe quantum dots

NASA Astrophysics Data System (ADS)

Geiregat, Pieter; Houtepen, Arjan J.; Sagar, Laxmi Kishore; Infante, Ivan; Zapata, Felipe; Grigel, Valeriia; Allan, Guy; Delerue, Christophe; van Thourhout, Dries; Hens, Zeger

2018-01-01

Colloidal quantum dots (QDs) raise more and more interest as solution-processable and tunable optical gain materials. However, especially for infrared active QDs, optical gain remains inefficient. Since stimulated emission involves multifold degenerate band-edge states, population inversion can be attained only at high pump power and must compete with efficient multi-exciton recombination. Here, we show that mercury telluride (HgTe) QDs exhibit size-tunable stimulated emission throughout the near-infrared telecom window at thresholds unmatched by any QD studied before. We attribute this unique behaviour to surface-localized states in the bandgap that turn HgTe QDs into 4-level systems. The resulting long-lived population inversion induces amplified spontaneous emission under continuous-wave optical pumping at power levels compatible with solar irradiation and direct current electrical pumping. These results introduce an alternative approach for low-threshold QD-based gain media based on intentional trap states that paves the way for solution-processed infrared QD lasers and amplifiers.

Novel applications of photonic signal processing: Temporal cloaking and biphoton pulse shaping

NASA Astrophysics Data System (ADS)

Lukens, Joseph M.

We experimentally demonstrate two innovative applications of photonic technologies previously solidified in the field of classical optical communications. In the first application, we exploit electro-optic modulator technology to develop a novel "time cloak,'' a device which hides events in time by manipulating the flow of a probing light beam. Our temporal cloak is capable of masking high-speed optical data from a receiver, greatly improving the feasibility of time cloaking and bringing such exotic concepts to the verge of practical application. In the second specialization, high-resolution Fourier-transform pulse shaping---perfected for multi-wavelength telecom networks---is applied to shape the correlations of entangled photon pairs, states which have received considerable attention in nonlocal tests of quantum theory and in quantum key distribution. Using nonlinear waveguides fabricated out of periodically poled lithium niobate, we are able to demonstrate ultrafast coincidence detection with record-high efficiency, which coupled with our pulse shaper allows us to realize for the first time several capabilities in biphoton control, including high-order dispersion cancellation, orthogonal spectral coding, correlation train generation, and tunable delay control. Each of these experiments represents an important advance in quantum state manipulation, with the potential to impact developments in quantum information. And more generally, our work introducing telecommunication technology into both temporal cloaking and biphoton control highlights the potential of such tools in more nascent outgrowths of classical and quantum optics.

Robust quantum network architectures and topologies for entanglement distribution

NASA Astrophysics Data System (ADS)

Das, Siddhartha; Khatri, Sumeet; Dowling, Jonathan P.

2018-01-01

Entanglement distribution is a prerequisite for several important quantum information processing and computing tasks, such as quantum teleportation, quantum key distribution, and distributed quantum computing. In this work, we focus on two-dimensional quantum networks based on optical quantum technologies using dual-rail photonic qubits for the building of a fail-safe quantum internet. We lay out a quantum network architecture for entanglement distribution between distant parties using a Bravais lattice topology, with the technological constraint that quantum repeaters equipped with quantum memories are not easily accessible. We provide a robust protocol for simultaneous entanglement distribution between two distant groups of parties on this network. We also discuss a memory-based quantum network architecture that can be implemented on networks with an arbitrary topology. We examine networks with bow-tie lattice and Archimedean lattice topologies and use percolation theory to quantify the robustness of the networks. In particular, we provide figures of merit on the loss parameter of the optical medium that depend only on the topology of the network and quantify the robustness of the network against intermittent photon loss and intermittent failure of nodes. These figures of merit can be used to compare the robustness of different network topologies in order to determine the best topology in a given real-world scenario, which is critical in the realization of the quantum internet.

Quantum Optics in Phase Space

NASA Astrophysics Data System (ADS)

Schleich, Wolfgang P.

2001-04-01

Quantum Optics in Phase Space provides a concise introduction to the rapidly moving field of quantum optics from the point of view of phase space. Modern in style and didactically skillful, Quantum Optics in Phase Space prepares students for their own research by presenting detailed derivations, many illustrations and a large set of workable problems at the end of each chapter. Often, the theoretical treatments are accompanied by the corresponding experiments. An exhaustive list of references provides a guide to the literature. Quantum Optics in Phase Space also serves advanced researchers as a comprehensive reference book. Starting with an extensive review of the experiments that define quantum optics and a brief summary of the foundations of quantum mechanics the author Wolfgang P. Schleich illustrates the properties of quantum states with the help of the Wigner phase space distribution function. His description of waves ala WKB connects semi-classical phase space with the Berry phase. These semi-classical techniques provide deeper insight into the timely topics of wave packet dynamics, fractional revivals and the Talbot effect. Whereas the first half of the book deals with mechanical oscillators such as ions in a trap or atoms in a standing wave the second half addresses problems where the quantization of the radiation field is of importance. Such topics extensively discussed include optical interferometry, the atom-field interaction, quantum state preparation and measurement, entanglement, decoherence, the one-atom maser and atom optics in quantized light fields. Quantum Optics in Phase Space presents the subject of quantum optics as transparently as possible. Giving wide-ranging references, it enables students to study and solve problems with modern scientific literature. The result is a remarkably concise yet comprehensive and accessible text- and reference book - an inspiring source of information and insight for students, teachers and researchers alike.

Adiabatic Quantum Computation: Coherent Control Back Action.

PubMed

Goswami, Debabrata

2006-11-22

Though attractive from scalability aspects, optical approaches to quantum computing are highly prone to decoherence and rapid population loss due to nonradiative processes such as vibrational redistribution. We show that such effects can be reduced by adiabatic coherent control, in which quantum interference between multiple excitation pathways is used to cancel coupling to the unwanted, non-radiative channels. We focus on experimentally demonstrated adiabatic controlled population transfer experiments wherein the details on the coherence aspects are yet to be explored theoretically but are important for quantum computation. Such quantum computing schemes also form a back-action connection to coherent control developments.

Quantum teleportation from light beams to vibrational states of a macroscopic diamond

PubMed Central

Hou, P.-Y.; Huang, Y.-Y.; Yuan, X.-X.; Chang, X.-Y.; Zu, C.; He, L.; Duan, L.-M.

2016-01-01

With the recent development of optomechanics, the vibration in solids, involving collective motion of trillions of atoms, gradually enters into the realm of quantum control. Here, building on the recent remarkable progress in optical control of motional states of diamonds, we report an experimental demonstration of quantum teleportation from light beams to vibrational states of a macroscopic diamond under ambient conditions. Through quantum process tomography, we demonstrate average teleportation fidelity (90.6±1.0)%, clearly exceeding the classical limit of 2/3. The experiment pushes the target of quantum teleportation to the biggest object so far, with interesting implications for optomechanical quantum control and quantum information science. PMID:27240553

Manipulating and probing angular momentum and quantized circulation in optical fields and matter waves

NASA Astrophysics Data System (ADS)

Lowney, Joseph Daniel

Methods to generate, manipulate, and measure optical and atomic fields with global or local angular momentum have a wide range of applications in both fundamental physics research and technology development. In optics, the engineering of angular momentum states of light can aid studies of orbital angular momentum (OAM) exchange between light and matter. The engineering of optical angular momentum states can also be used to increase the bandwidth of optical communications or serve as a means to distribute quantum keys, for example. Similar capabilities in Bose-Einstein condensates are being investigated to improve our understanding of superfluid dynamics, superconductivity, and turbulence, the last of which is widely considered to be one of most ubiquitous yet poorly understood subjects in physics. The first part of this two-part dissertation presents an analysis of techniques for measuring and manipulating quantized vortices in BECs. The second part of this dissertation presents theoretical and numerical analyses of new methods to engineer the OAM spectra of optical beams. The superfluid dynamics of a BEC are often well described by a nonlinear Schrodinger equation. The nonlinearity arises from interatomic scattering and enables BECs to support quantized vortices, which have quantized circulation and are fundamental structural elements of quantum turbulence. With the experimental tools to dynamically manipulate and measure quantized vortices, BECs are proving to be a useful medium for testing the theoretical predictions of quantum turbulence. In this dissertation we analyze a method for making minimally destructive in situ observations of quantized vortices in a BEC. Secondly, we numerically study a mechanism to imprint vortex dipoles in a BEC. With these advancements, more robust experiments of vortex dynamics and quantum turbulence will be within reach. A more complete understanding of quantum turbulence will enable principles of microscopic fluid flow to be related to the statistical properties of turbulence in a superfluid. In the second part of this dissertation we explore frequency mixing, a subset of nonlinear optical processes in which one or more input optical beam(s) are converted into one or more output beams with different optical frequencies. The ability of parametric nonlinear processes such as second harmonic generation or parametric amplification to manipulate the OAM spectra of optical beams is an active area of research. In a theoretical and numerical investigation, two complimentary methods for sculpting the OAM spectra are developed. The first method employs second harmonic generation with two non-collinear input beams to develop a broad spectrum of OAM states in an optical field. The second method utilizes parametric amplification with collinear input beams to develop an OAM-dependent gain or attenuation, termed dichroism for OAM, to effectively narrow the OAM spectrum of an optical beam. The theoretical principles developed in this dissertation enhance our understanding of how nonlinear processes can be used to engineer the OAM spectra of optical beams and could serve as methods to increase the bandwidth of an optical signal by multiplexing over a range of OAM states.

Time-reversal-symmetric single-photon wave packets for free-space quantum communication.

PubMed

Trautmann, N; Alber, G; Agarwal, G S; Leuchs, G

2015-05-01

Readout and retrieval processes are proposed for efficient, high-fidelity quantum state transfer between a matter qubit, encoded in the level structure of a single atom or ion, and a photonic qubit, encoded in a time-reversal-symmetric single-photon wave packet. They are based on controlling spontaneous photon emission and absorption of a matter qubit on demand in free space by stimulated Raman adiabatic passage. As these processes do not involve mode selection by high-finesse cavities or photon transport through optical fibers, they offer interesting perspectives as basic building blocks for free-space quantum-communication protocols.

Effect of growth interruption in 1.55 μm InAs/InAlGaAs quantum dots on InP grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Jung, Daehwan; Ironside, Daniel J.; Bank, Seth R.; Gossard, Arthur C.; Bowers, John E.

2018-05-01

We report the effect of growth interruptions on the structural and optical properties of InAs/InAlGaAs/InP quantum dots using molecular beam epitaxy. We find that the surface quantum dots experience an unintended ripening process during the sample cooling stage, which reshapes the uncapped InAs nanostructures. To prevent this, we performed a partial capping experiment to effectively inhibit structural reconfiguration of surface InAs nanostructures during the cooling stage, revealing that InAs nanostructures first form quantum dashes and then transform into quantum dots via a ripening process. Our result suggests that the appearance of buried InAs/InAlGaAs nanostructures can be easily misunderstood by surface analysis.

Experimental observation of spatial quantum noise reduction below the standard quantum limit with bright twin beams of light

NASA Astrophysics Data System (ADS)

Kumar, Ashok; Nunley, Hayden; Marino, Alberto

2016-05-01

Quantum noise reduction (QNR) below the standard quantum limit (SQL) has been a subject of interest for the past two to three decades due to its wide range of applications in quantum metrology and quantum information processing. To date, most of the attention has focused on the study of QNR in the temporal domain. However, many areas in quantum optics, specifically in quantum imaging, could benefit from QNR not only in the temporal domain but also in the spatial domain. With the use of a high quantum efficiency electron multiplier charge coupled device (EMCCD) camera, we have observed spatial QNR below the SQL in bright narrowband twin light beams generated through a four-wave mixing (FWM) process in hot rubidium atoms. Owing to momentum conservation in this process, the twin beams are momentum correlated. This leads to spatial quantum correlations and spatial QNR. Our preliminary results show a spatial QNR of over 2 dB with respect to the SQL. Unlike previous results on spatial QNR with faint and broadband photon pairs from parametric down conversion (PDC), we demonstrate spatial QNR with spectrally and spatially narrowband bright light beams. The results obtained will be useful for atom light interaction based quantum protocols and quantum imaging. Work supported by the W.M. Keck Foundation.

Coherent optical excitations in superconducting qubit chain

NASA Astrophysics Data System (ADS)

Ian, Hou; Liu, Yu-Xi

2012-06-01

In the recent years, the theories of quantum optics have been borrowed to study the flows of electron pairs and their interactions with the circuit photon in the superconducting qubit circuits. These studies bring about new theories of quantum optics, such as the tunable electromagnetically induced transparency effect, peculiar to the Cooper pairs in circuits. In this talk, we focus on a special type of superconducting qubit circuits: superconducting qubit chain (SQC), which comprises dozens of qubits linearly placed along a stripline resonator. Since the dimensions of the qubits and the stripline have made their interactions inhomogeneous, the SQC cannot be diagonalized using the usual Dicke model. We present a new theoretical method, the deformation-projection method, for the exact diagonalization of the collective excitations of the qubits. This method allows us to predict that these excitations emulate the behaviors of Wannier and Frenckel excitons in the solid-state systems. The spontaneous emissions from the individual qubits in SQC are relayed to their neighbors, eventually arriving at a coherent emission, known as superradiance. We present a quantum relay model, which is crucial to quantum information processing, based on this finding.

Study on spin and optical polarization in a coupled InGaN/GaN quantum well and quantum dots structure.

PubMed

Yu, Jiadong; Wang, Lai; Di Yang; Zheng, Jiyuan; Xing, Yuchen; Hao, Zhibiao; Luo, Yi; Sun, Changzheng; Han, Yanjun; Xiong, Bing; Wang, Jian; Li, Hongtao

2016-10-19

The spin and optical polarization based on a coupled InGaN/GaN quantum well (QW) and quantum dots (QDs) structure is investigated. In this structure, spin-electrons can be temporarily stored in QW, and spin injection from the QW into QDs via spin-conserved tunneling is enabled. Spin relaxation can be suppressed owing to the small energy difference between the initial state in the QW and the final states in the QDs. Photoluminescence (PL) and time-resolved photoluminescence (TRPL) measurements are carried out on optical spin-injection and -detection. Owing to the coupled structure, spin-conserved tunneling mechanism plays a significant role in preventing spin relaxation process. As a result, a higher circular polarization degree (CPD) (~49.1%) is achieved compared with conventional single layer of QDs structure. Moreover, spin relaxation time is also extended to about 2.43 ns due to the weaker state-filling effect. This coupled structure is believed an appropriate candidate for realization of spin-polarized light source.

Efficient quantum microwave-to-optical conversion using electro-optic nanophotonic coupled resonators

NASA Astrophysics Data System (ADS)

Soltani, Mohammad; Zhang, Mian; Ryan, Colm; Ribeill, Guilhem J.; Wang, Cheng; Loncar, Marko

2017-10-01

We propose a low-noise, triply resonant, electro-optic (EO) scheme for quantum microwave-to-optical conversion based on coupled nanophotonics resonators integrated with a superconducting qubit. Our optical system features a split resonance—a doublet—with a tunable frequency splitting that matches the microwave resonance frequency of the superconducting qubit. This is in contrast to conventional approaches, where large optical resonators with free-spectral range comparable to the qubit microwave frequency are used. In our system, EO mixing between the optical pump coupled into the low-frequency doublet mode and a resonance microwave photon results in an up-converted optical photon on resonance with high-frequency doublet mode. Importantly, the down-conversion process, which is the source of noise, is suppressed in our scheme as the coupled-resonator system does not support modes at that frequency. Our device has at least an order of magnitude smaller footprint than conventional devices, resulting in large overlap between optical and microwave fields and a large photon conversion rate (g /2 π ) in the range of ˜5 -15 kHz. Owing to a large g factor and doubly resonant nature of our device, microwave-to-optical frequency conversion can be achieved with optical pump powers in the range of tens of microwatts, even with moderate values for optical Q (˜106 ) and microwave Q (˜104 ). The performance metrics of our device, with substantial improvement over the previous EO-based approaches, promise a scalable quantum microwave-to-optical conversion and networking of superconducting processors via optical fiber communication.

Leveraging Nanocavity Harmonics for Control of Optical Processes in 2D Semiconductors

DOE PAGES

Akselrod, Gleb M.; Ming, Tian; Argyropoulos, Christos; ...

2015-04-07

Optical cavities with multiple tunable resonances have the potential to provide unique electromagnetic environments at two or more distinct wavelengths–critical for control of optical processes such as nonlinear generation, entangled photon generation, or photoluminescence (PL) enhancement. Here, we show a plasmonic nanocavity based on a nanopatch antenna design that has two tunable resonant modes in the visible spectrum separated by 350 nm and with line widths of ~60 nm. The importance of utilizing two resonances simultaneously is demonstrated by integrating monolayer MoS 2, a two-dimensional semiconductor, into the colloidally synthesized nanocavities. Here, we observe a 2000-fold enhancement in the PLmore » intensity of MoS 2– which has intrinsically low absorption and small quantum yield–at room temperature, enabled by the combination of tailored absorption enhancement at the first harmonic and PL quantum-yield enhancement at the fundamental resonance.« less

Engineered Quasi-Phase Matching for Nonlinear Quantum Optics in Waveguides

NASA Astrophysics Data System (ADS)

Van Camp, Mackenzie A.

Entanglement is the hallmark of quantum mechanics. Quantum entanglement--putting two or more identical particles into a non-factorable state--has been leveraged for applications ranging from quantum computation and encryption to high-precision metrology. Entanglement is a practical engineering resource and a tool for sidestepping certain limitations of classical measurement and communication. Engineered nonlinear optical waveguides are an enabling technology for generating entangled photon pairs and manipulating the state of single photons. This dissertation reports on: i) frequency conversion of single photons from the mid-infrared to 843nm as a tool for incorporating quantum memories in quantum networks, ii) the design, fabrication, and test of a prototype broadband source of polarization and frequency entangled photons; and iii) a roadmap for further investigations of this source, including applications in quantum interferometry and high-precision optical metrology. The devices presented herein are quasi-phase-matched lithium niobate waveguides. Lithium niobate is a second-order nonlinear optical material and can mediate optical energy conversion to different wavelengths. This nonlinear effect is the basis of both quantum frequency conversion and entangled photon generation, and is enhanced by i) confining light in waveguides to increase conversion efficiency, and ii) quasi-phase matching, a technique for engineering the second-order nonlinear response by locally altering the direction of a material's polarization vector. Waveguides are formed by diffusing titanium into a lithium niobate wafer. Quasi-phase matching is achieved by electric field poling, with multiple stages of process development and optimization to fabricate the delicate structures necessary for broadband entangled photon generation. The results presented herein update and optimize past fabrication techniques, demonstrate novel optical devices, and propose future avenues for device development. Quantum frequency conversion from 1848nm to 843nm is demonstrated for the first time, with >75% single-photon conversion efficiency. A new electric field poling methodology is presented, combining elements from multiple historical techniques with a new fast-feedback control system. This poling technique is used to fabricate the first chirped-and-apodized Type-II quasi-phase-matched structures in titanium-diffused lithium niobate waveguides, culminating in a measured phasematching spectrum that is predominantly Gaussian ( R2 = 0.80), nearly eight times broader than the unchirped spectrum, and agrees well with simulations.

CALL FOR PAPERS: Optical implementation of quantum computers

NASA Astrophysics Data System (ADS)

Rarity, John; Weinfurter, Harald

2004-09-01

A topical issue of Journal of Optics B: Quantum and Semiclassical Optics will be devoted to recent advances in optical implementation of quantum computers. The topics to be covered will include, but are not limited to: bullet Linear optics quantum gates bullet Progress towards nonlinear optics quantum gates bullet Interface between optical qubits and atomic/solid state qubits bullet Novel architectures bullet Single-photon sources and detectors bullet Photonic quantum networks bullet Few-qubit applications The DEADLINE for submission of contributions is 15 January 2005 to allow the topical issue to be published in about October 2005. All contributions will be peer-reviewed in accordance with the normal refereeing procedures and standards of Journal of Optics B: Quantum and Semiclassical Optics. Submissions should preferably be in either standard LaTeX form or Microsoft Word. Advice on publishing your work in the journal may be found at www.iop.org/journals/authors/jopb. There are no page charges for publication. The corresponding author of each paper published will receive a complimentary copy of the topical issue. Contributions to the topical issue should preferably be submitted electronically at www.iop.org/journals/authors/jopb or by e-mail to jopb@iop.org. Authors unable to submit online or by e-mail may send hard copy contributions (enclosing the electronic code) to: Dr Claire Bedrock (Publisher), Journal of Optics B: Quantum and Semiclassical Optics, Institute of Physics Publishing, Dirac House, Temple Back, Bristol BS1 6BE, UK. All contributions should be accompanied by a readme file or covering letter, quoting `JOPB Topical Issue - Optical implementation of quantum computers', giving the postal and e-mail addresses for correspondence. Any subsequent change of address should be notified to the publishing office. We look forward to receiving your contribution to this topical issue.

Gaussian error correction of quantum states in a correlated noisy channel.

PubMed

Lassen, Mikael; Berni, Adriano; Madsen, Lars S; Filip, Radim; Andersen, Ulrik L

2013-11-01

Noise is the main obstacle for the realization of fault-tolerant quantum information processing and secure communication over long distances. In this work, we propose a communication protocol relying on simple linear optics that optimally protects quantum states from non-Markovian or correlated noise. We implement the protocol experimentally and demonstrate the near-ideal protection of coherent and entangled states in an extremely noisy channel. Since all real-life channels are exhibiting pronounced non-Markovian behavior, the proposed protocol will have immediate implications in improving the performance of various quantum information protocols.

Quantum feedback cooling of a mechanical oscillator using variational measurements: tweaking Heisenberg’s microscope

NASA Astrophysics Data System (ADS)

Habibi, Hojat; Zeuthen, Emil; Ghanaatshoar, Majid; Hammerer, Klemens

2016-08-01

We revisit the problem of preparing a mechanical oscillator in the vicinity of its quantum-mechanical ground state by means of feedback cooling based on continuous optical detection of the oscillator position. In the parameter regime relevant to ground-state cooling, the optical back-action and imprecision noise set the bottleneck of achievable cooling and must be carefully balanced. This can be achieved by adapting the phase of the local oscillator in the homodyne detection realizing a so-called variational measurement. The trade-off between accurate position measurement and minimal disturbance can be understood in terms of Heisenberg’s microscope and becomes particularly relevant when the measurement and feedback processes happen to be fast within the quantum coherence time of the system to be cooled. This corresponds to the regime of large quantum cooperativity {C}{{q}}≳ 1, which was achieved in recent experiments on feedback cooling. Our method provides a simple path to further pushing the limits of current state-of-the-art experiments in quantum optomechanics.

Fundamental limits to single-photon detection determined by quantum coherence and backaction

NASA Astrophysics Data System (ADS)

Young, Steve M.; Sarovar, Mohan; Léonard, François

2018-03-01

Single-photon detectors have achieved impressive performance and have led to a number of new scientific discoveries and technological applications. Existing models of photodetectors are semiclassical in that the field-matter interaction is treated perturbatively and time-separated from physical processes in the absorbing matter. An open question is whether a fully quantum detector, whereby the optical field, the optical absorption, and the amplification are considered as one quantum system, could have improved performance. Here we develop a theoretical model of such photodetectors and employ simulations to reveal the critical role played by quantum coherence and amplification backaction in dictating the performance. We show that coherence and backaction lead to trade-offs between detector metrics and also determine optimal system designs through control of the quantum-classical interface. Importantly, we establish the design parameters that result in a ideal photodetector with 100% efficiency, no dark counts, and minimal jitter, thus paving the route for next-generation detectors.

Method for universal detection of two-photon polarization entanglement

NASA Astrophysics Data System (ADS)

Bartkiewicz, Karol; Horodecki, Paweł; Lemr, Karel; Miranowicz, Adam; Życzkowski, Karol

2015-03-01

Detecting and quantifying quantum entanglement of a given unknown state poses problems that are fundamentally important for quantum information processing. Surprisingly, no direct (i.e., without quantum tomography) universal experimental implementation of a necessary and sufficient test of entanglement has been designed even for a general two-qubit state. Here we propose an experimental method for detecting a collective universal witness, which is a necessary and sufficient test of two-photon polarization entanglement. It allows us to detect entanglement for any two-qubit mixed state and to establish tight upper and lower bounds on its amount. A different element of this method is the sequential character of its main components, which allows us to obtain relatively complicated information about quantum correlations with the help of simple linear-optical elements. As such, this proposal realizes a universal two-qubit entanglement test within the present state of the art of quantum optics. We show the optimality of our setup with respect to the minimal number of measured quantities.

Ultralow-power and ultrafast all-optical tunable plasmon-induced transparency in metamaterials at optical communication range.

PubMed

Zhu, Yu; Hu, Xiaoyong; Fu, Yulan; Yang, Hong; Gong, Qihuang

2013-01-01

Actively all-optical tunable plasmon-induced transparency in metamaterials paves the way for achieving ultrahigh-speed quantum information processing chips. Unfortunately, up to now, very small experimental progress has been made for all-optical tunable plasmon-induced transparency in metamaterials in the visible and near-infrared range because of small third-order optical nonlinearity of conventional materials. The achieved operating pump intensity was as high as several GW/cm(2) order. Here, we report an ultralow-power and ultrafast all-optical tunable plasmon-induced transparency in metamaterials coated on polycrystalline indium-tin oxide layer at the optical communication range. Compared with previous reports, the threshold pump intensity is reduced by four orders of magnitude, while an ultrafast response time of picoseconds order is maintained. This work not only offers a way to constructing photonic materials with large nonlinearity and ultrafast response, but also opens up the possibility for realizing quantum solid chips and ultrafast integrated photonic devices based on metamaterials.

Ultralow-power and ultrafast all-optical tunable plasmon-induced transparency in metamaterials at optical communication range

PubMed Central

Zhu, Yu; Hu, Xiaoyong; Fu, Yulan; Yang, Hong; Gong, Qihuang

2013-01-01

Actively all-optical tunable plasmon-induced transparency in metamaterials paves the way for achieving ultrahigh-speed quantum information processing chips. Unfortunately, up to now, very small experimental progress has been made for all-optical tunable plasmon-induced transparency in metamaterials in the visible and near-infrared range because of small third-order optical nonlinearity of conventional materials. The achieved operating pump intensity was as high as several GW/cm2 order. Here, we report an ultralow-power and ultrafast all-optical tunable plasmon-induced transparency in metamaterials coated on polycrystalline indium-tin oxide layer at the optical communication range. Compared with previous reports, the threshold pump intensity is reduced by four orders of magnitude, while an ultrafast response time of picoseconds order is maintained. This work not only offers a way to constructing photonic materials with large nonlinearity and ultrafast response, but also opens up the possibility for realizing quantum solid chips and ultrafast integrated photonic devices based on metamaterials. PMID:23903825

Stimulated Raman adiabatic passage in physics, chemistry, and beyond

NASA Astrophysics Data System (ADS)

Vitanov, Nikolay V.; Rangelov, Andon A.; Shore, Bruce W.; Bergmann, Klaas

2017-01-01

The technique of stimulated Raman adiabatic passage (STIRAP), which allows efficient and selective population transfer between quantum states without suffering loss due to spontaneous emission, was introduced in 1990 by Gaubatz et al.. Since then STIRAP has emerged as an enabling methodology with widespread successful applications in many fields of physics, chemistry, and beyond. This article reviews the many applications of STIRAP emphasizing the developments since 2001, the time when the last major review on the topic was written (Vitanov, Fleischhauer et al.). A brief introduction into the theory of STIRAP and the early applications for population transfer within three-level systems is followed by the discussion of several extensions to multilevel systems, including multistate chains and tripod systems. The main emphasis is on the wide range of applications in atomic and molecular physics (including atom optics, cavity quantum electrodynamics, formation of ultracold molecules, etc.), quantum information (including single- and two-qubit gates, entangled-state preparation, etc.), solid-state physics (including processes in doped crystals, nitrogen-vacancy centers, superconducting circuits, semiconductor quantum dots and wells), and even some applications in classical physics (including waveguide optics, polarization optics, frequency conversion, etc.). Promising new prospects for STIRAP are also presented (including processes in optomechanics, precision experiments, detection of parity violation in molecules, spectroscopy of core-nonpenetrating Rydberg states, population transfer with x-ray pulses, etc.).

High Photoluminescence Quantum Yield in Band Gap Tunable Bromide Containing Mixed Halide Perovskites.

PubMed

Sutter-Fella, Carolin M; Li, Yanbo; Amani, Matin; Ager, Joel W; Toma, Francesca M; Yablonovitch, Eli; Sharp, Ian D; Javey, Ali

2016-01-13

Hybrid organic-inorganic halide perovskite based semiconductor materials are attractive for use in a wide range of optoelectronic devices because they combine the advantages of suitable optoelectronic attributes and simultaneously low-cost solution processability. Here, we present a two-step low-pressure vapor-assisted solution process to grow high quality homogeneous CH3NH3PbI3-xBrx perovskite films over the full band gap range of 1.6-2.3 eV. Photoluminescence light-in versus light-out characterization techniques are used to provide new insights into the optoelectronic properties of Br-containing hybrid organic-inorganic perovskites as a function of optical carrier injection by employing pump-powers over a 6 orders of magnitude dynamic range. The internal luminescence quantum yield of wide band gap perovskites reaches impressive values up to 30%. This high quantum yield translates into substantial quasi-Fermi level splitting and high "luminescence or optically implied" open-circuit voltage. Most importantly, both attributes, high internal quantum yield and high optically implied open-circuit voltage, are demonstrated over the entire band gap range (1.6 eV ≤ Eg ≤ 2.3 eV). These results establish the versatility of Br-containing perovskite semiconductors for a variety of applications and especially for the use as high-quality top cell in tandem photovoltaic devices in combination with industry dominant Si bottom cells.

Quantum Storage of Three-Dimensional Orbital-Angular-Momentum Entanglement in a Crystal.

PubMed

Zhou, Zong-Quan; Hua, Yi-Lin; Liu, Xiao; Chen, Geng; Xu, Jin-Shi; Han, Yong-Jian; Li, Chuan-Feng; Guo, Guang-Can

2015-08-14

Here we present the quantum storage of three-dimensional orbital-angular-momentum photonic entanglement in a rare-earth-ion-doped crystal. The properties of the entanglement and the storage process are confirmed by the violation of the Bell-type inequality generalized to three dimensions after storage (S=2.152±0.033). The fidelity of the memory process is 0.993±0.002, as determined through complete quantum process tomography in three dimensions. An assessment of the visibility of the stored weak coherent pulses in higher-dimensional spaces demonstrates that the memory is highly reliable for 51 spatial modes. These results pave the way towards the construction of high-dimensional and multiplexed quantum repeaters based on solid-state devices. The multimode capacity of rare-earth-based optical processors goes beyond the temporal and the spectral degree of freedom, which might provide a useful tool for photonic information processing.

Requirements for fault-tolerant factoring on an atom-optics quantum computer.

PubMed

Devitt, Simon J; Stephens, Ashley M; Munro, William J; Nemoto, Kae

2013-01-01

Quantum information processing and its associated technologies have reached a pivotal stage in their development, with many experiments having established the basic building blocks. Moving forward, the challenge is to scale up to larger machines capable of performing computational tasks not possible today. This raises questions that need to be urgently addressed, such as what resources these machines will consume and how large will they be. Here we estimate the resources required to execute Shor's factoring algorithm on an atom-optics quantum computer architecture. We determine the runtime and size of the computer as a function of the problem size and physical error rate. Our results suggest that once the physical error rate is low enough to allow quantum error correction, optimization to reduce resources and increase performance will come mostly from integrating algorithms and circuits within the error correction environment, rather than from improving the physical hardware.

Exchange interaction and the tunneling induced transparency in coupled quantum dots

NASA Astrophysics Data System (ADS)

Borges, Halyne; Alcalde, Augusto; Ulloa, Sergio

2014-03-01

Stacked semiconductor quantum dots coupled by tunneling are unique ``quantum molecule'' where it is possible to create a multilevel structure of excitonic states. This structure allows the investigation of quantum interference processes and their control via electric external fields. In this work, we investigate the optical response of a quantum molecule coherently driven by a polarized laser, considering the splitting in excitonic levels caused by isotropic and anisotropic exchange interactions. In our model we consider interdot transitions mediated by the the hole tunneling between states with the same total spin and, between bright and dark exciton states. Using realistic experimental parameters, we demonstrate that the excitonic states coupled by tunneling exhibit an enriched and controllable optical response. Our results show that through the appropriate control of the external electric field and light polarization, the tunneling coupling establishes an efficient destructive quantum interference path that creates a transparency window in the absorption spectra, whenever states of appropriate symmetry are mixed by the hole tunneling. We explore the relevant parameters space that would allows with the experiments. CAPES, INCT-IQ and MWN/CIAM-NSF.

Synthetic Control of Exciton Behavior in Colloidal Quantum Dots.

PubMed

Pu, Chaodan; Qin, Haiyan; Gao, Yuan; Zhou, Jianhai; Wang, Peng; Peng, Xiaogang

2017-03-08

Colloidal quantum dots are promising optical and optoelectronic materials for various applications, whose performance is dominated by their excited-state properties. This article illustrates synthetic control of their excited states. Description of the excited states of quantum-dot emitters can be centered around exciton. We shall discuss that, different from conventional molecular emitters, ground-state structures of quantum dots are not necessarily correlated with their excited states. Synthetic control of exciton behavior heavily relies on convenient and affordable monitoring tools. For synthetic development of ideal optical and optoelectronic emitters, the key process is decay of band-edge excitons, which renders transient photoluminescence as important monitoring tool. On the basis of extensive synthetic developments in the past 20-30 years, synthetic control of exciton behavior implies surface engineering of quantum dots, including surface cation/anion stoichiometry, organic ligands, inorganic epitaxial shells, etc. For phosphors based on quantum dots doped with transition metal ions, concentration and location of the dopant ions within a nanocrystal lattice are found to be as important as control of the surface states in order to obtain bright dopant emission with monoexponential yet tunable photoluminescence decay dynamics.

Quantum Limits of Space-to-Ground Optical Communications

NASA Technical Reports Server (NTRS)

Hemmati, H.; Dolinar, S.

2012-01-01

Quantum limiting factors contributed by the transmitter, the optical channel, and the receiver of a space-to-ground optical communications link are described. Approaches to move toward the ultimate quantum limit are discussed.

On the photonic implementation of universal quantum gates, bell states preparation circuit and quantum LDPC encoders and decoders based on directional couplers and HNLF.

PubMed

Djordjevic, Ivan B

2010-04-12

The Bell states preparation circuit is a basic circuit required in quantum teleportation. We describe how to implement it in all-fiber technology. The basic building blocks for its implementation are directional couplers and highly nonlinear optical fiber (HNLF). Because the quantum information processing is based on delicate superposition states, it is sensitive to quantum errors. In order to enable fault-tolerant quantum computing the use of quantum error correction is unavoidable. We show how to implement in all-fiber technology encoders and decoders for sparse-graph quantum codes, and provide an illustrative example to demonstrate this implementation. We also show that arbitrary set of universal quantum gates can be implemented based on directional couplers and HNLFs.

Optical bandgap of semiconductor nanostructures: Methods for experimental data analysis

NASA Astrophysics Data System (ADS)

Raciti, R.; Bahariqushchi, R.; Summonte, C.; Aydinli, A.; Terrasi, A.; Mirabella, S.

2017-06-01

Determination of the optical bandgap (Eg) in semiconductor nanostructures is a key issue in understanding the extent of quantum confinement effects (QCE) on electronic properties and it usually involves some analytical approximation in experimental data reduction and modeling of the light absorption processes. Here, we compare some of the analytical procedures frequently used to evaluate the optical bandgap from reflectance (R) and transmittance (T) spectra. Ge quantum wells and quantum dots embedded in SiO2 were produced by plasma enhanced chemical vapor deposition, and light absorption was characterized by UV-Vis/NIR spectrophotometry. R&T elaboration to extract the absorption spectra was conducted by two approximated methods (single or double pass approximation, single pass analysis, and double pass analysis, respectively) followed by Eg evaluation through linear fit of Tauc or Cody plots. Direct fitting of R&T spectra through a Tauc-Lorentz oscillator model is used as comparison. Methods and data are discussed also in terms of the light absorption process in the presence of QCE. The reported data show that, despite the approximation, the DPA approach joined with Tauc plot gives reliable results, with clear advantages in terms of computational efforts and understanding of QCE.

Photoexcited escape probability, optical gain, and noise in quantum well infrared photodetectors

NASA Technical Reports Server (NTRS)

Levine, B. F.; Zussman, A.; Gunapala, S. D.; Asom, M. T.; Kuo, J. M.; Hobson, W. S.

1992-01-01

We present a detailed and thorough study of a wide variety of quantum well infrared photodetectors (QWIPs), which were chosen to have large differences in their optical and transport properties. Both n- and p-doped QWIPs, as well as intersubband transitions based on photoexcitation from bound-to-bound, bound-to-quasi-continuum, and bound-to-continuum quantum well states were investigated. The measurements and theoretical analysis included optical absorption, responsivity, dark current, current noise, optical gain, hot carrier mean free path; net quantum efficiency, quantum well escape probability, quantum well escape time, as well as detectivity. These results allow a better understanding of the optical and transport physics and thus a better optimization of the QWIP performance.

Range detection using entangled optical photons

NASA Astrophysics Data System (ADS)

Brandsema, Matthew J.; Narayanan, Ram M.; Lanzagorta, Marco

2015-05-01

Quantum radar is an emerging field that shows a lot of promise in providing significantly improved resolution compared to its classical radar counterpart. The key to this kind of resolution lies in the correlations created from the entanglement of the photons being used. Currently, the technology available only supports quantum radar implementation and validation in the optical regime, as opposed to the microwave regime, because microwave photons have very low energy compared to optical photons. Furthermore, there currently do not exist practical single photon detectors and generators in the microwave spectrum. Viable applications in the optical regime include deep sea target detection and high resolution detection in space. In this paper, we propose a conceptual architecture of a quantum radar which uses entangled optical photons based on Spontaneous Parametric Down Conversion (SPDC) methods. After the entangled photons are created and emerge from the crystal, the idler photon is detected very shortly thereafter. At the same time, the signal photon is sent out towards the target and upon its reflection will impinge on the detector of the radar. From these two measurements, correlation data processing is done to obtain the distance of the target away from the radar. Various simulations are then shown to display the resolution that is possible.

The Importance of Time and Frequency Reference in Quantum Astronomy and Quantum Communications

DTIC Science & Technology

2007-11-01

simulator, but the same general results are valid for optical fiber and also different quantum state transmission technologies (i.e. Entangled Photons ...protocols [6]). The Matlab simulation starts from a sequence of pulses of duration Ton; the number of photons per pulse has been implemented like a...astrophysical emission mechanisms or scattering processes by measuring the statistics of the arrival time of each incoming photon . This line of research will be

Quantum Confined Semiconductors

DTIC Science & Technology

2015-02-01

diodes [8-10], metamaterials [11-13], and solar cells [14,15]. As a consequence, the optical and electrical stability of colloidal quantum dots...PbS quantum dot solar cells with high fill factor,” ACS Nano, 4 (7), 3743–3752 (2010). [15] Gur, I., Fromer, N. A., Geier, M. L. and Alivisatos, A...P., “Air-stable all-inorganic nanocrystal solar cells processed from solution,” Sci. 310, 462–465 (2005). [16] Dai, Q., Wang, Y. N., Zhang, Y

Quantum Optical Transistor and Other Devices Based on Nanostructures

NASA Astrophysics Data System (ADS)

Li, Jin-Jin; Zhu, Ka-Di

Laser and strong coupling can coexist in a single quantum dot (QD) coupled to nanostructures. This provides an important clue toward the realization of quantum optical devices, such as quantum optical transistor, slow light device, fast light device, or light storage device. In contrast to conventional electronic transistor, a quantum optical transistor uses photons as signal carriers rather than electrons, which has a faster and more powerful transfer efficiency. Under the radiation of a strong pump laser, a signal laser can be amplified or attenuated via passing through a single quantum dot coupled to a photonic crystal (PC) nanocavity system. Such a switching and amplifying behavior can really implement the quantum optical transistor. By simply turning on or off the input pump laser, the amplified or attenuated signal laser can be obtained immediately. Based on this transistor, we further propose a method to measure the vacuum Rabi splitting of exciton in all-optical domain. Besides, we study the light propagation in a coupled QD and nanomechanical resonator (NR) system. We demonstrate that it is possible to achieve the slow light, fast light, and quantum memory for light on demand, which is based on the mechanically induced coherent population oscillation (MICPO) and exciton polaritons. These QD devices offer a route toward the use of all-optical technique to investigate the coupled QD systems and will make contributions to quantum internets and quantum computers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herbrych, Jacek W.; Feiguin, Adrian E.; Dagotto, Elbio R.

Here, we present a time-dependent density-matrix renormalization group investigation of the quantum distillation process within the Fermi-Hubbard model on a quasi-one-dimensional ladder geometry. The term distillation refers to the dynamical, spatial separation of singlons and doublons in the sudden expansion of interacting particles in an optical lattice, i.e., the release of a cloud of atoms from a trapping potential. Remarkably, quantum distillation can lead to a contraction of the doublon cloud, resulting in an increased density of the doublons in the core region compared to the initial state. As a main result, we show that this phenomenon is not limitedmore » to chains that were previously studied. Interestingly, there are additional dynamical processes on the two-leg ladder such as density oscillations and self-trapping of defects that lead to a less efficient distillation process. An investigation of the time evolution starting from product states provides an explanation for this behavior. Initial product states are also considered since in optical lattice experiments, such states are often used as the initial setup. We propose configurations that lead to a fast and efficient quantum distillation.« less

Quantum logic using correlated one-dimensional quantum walks

NASA Astrophysics Data System (ADS)

Lahini, Yoav; Steinbrecher, Gregory R.; Bookatz, Adam D.; Englund, Dirk

2018-01-01

Quantum Walks are unitary processes describing the evolution of an initially localized wavefunction on a lattice potential. The complexity of the dynamics increases significantly when several indistinguishable quantum walkers propagate on the same lattice simultaneously, as these develop non-trivial spatial correlations that depend on the particle's quantum statistics, mutual interactions, initial positions, and the lattice potential. We show that even in the simplest case of a quantum walk on a one dimensional graph, these correlations can be shaped to yield a complete set of compact quantum logic operations. We provide detailed recipes for implementing quantum logic on one-dimensional quantum walks in two general cases. For non-interacting bosons—such as photons in waveguide lattices—we find high-fidelity probabilistic quantum gates that could be integrated into linear optics quantum computation schemes. For interacting quantum-walkers on a one-dimensional lattice—a situation that has recently been demonstrated using ultra-cold atoms—we find deterministic logic operations that are universal for quantum information processing. The suggested implementation requires minimal resources and a level of control that is within reach using recently demonstrated techniques. Further work is required to address error-correction.

Quantum key distribution in a multi-user network at gigahertz clock rates

NASA Astrophysics Data System (ADS)

Fernandez, Veronica; Gordon, Karen J.; Collins, Robert J.; Townsend, Paul D.; Cova, Sergio D.; Rech, Ivan; Buller, Gerald S.

2005-07-01

In recent years quantum information research has lead to the discovery of a number of remarkable new paradigms for information processing and communication. These developments include quantum cryptography schemes that offer unconditionally secure information transport guaranteed by quantum-mechanical laws. Such potentially disruptive security technologies could be of high strategic and economic value in the future. Two major issues confronting researchers in this field are the transmission range (typically <100km) and the key exchange rate, which can be as low as a few bits per second at long optical fiber distances. This paper describes further research of an approach to significantly enhance the key exchange rate in an optical fiber system at distances in the range of 1-20km. We will present results on a number of application scenarios, including point-to-point links and multi-user networks. Quantum key distribution systems have been developed, which use standard telecommunications optical fiber, and which are capable of operating at clock rates of up to 2GHz. They implement a polarization-encoded version of the B92 protocol and employ vertical-cavity surface-emitting lasers with emission wavelengths of 850 nm as weak coherent light sources, as well as silicon single-photon avalanche diodes as the single photon detectors. The point-to-point quantum key distribution system exhibited a quantum bit error rate of 1.4%, and an estimated net bit rate greater than 100,000 bits-1 for a 4.2 km transmission range.

All-optical coherent population trapping with defect spin ensembles in silicon carbide.

PubMed

Zwier, Olger V; O'Shea, Danny; Onur, Alexander R; van der Wal, Caspar H

2015-06-05

Divacancy defects in silicon carbide have long-lived electronic spin states and sharp optical transitions. Because of the various polytypes of SiC, hundreds of unique divacancies exist, many with spin properties comparable to the nitrogen-vacancy center in diamond. If ensembles of such spins can be all-optically manipulated, they make compelling candidate systems for quantum-enhanced memory, communication, and sensing applications. We report here direct all-optical addressing of basal plane-oriented divacancy spins in 4H-SiC. By means of magneto-spectroscopy, we fully identify the spin triplet structure of both the ground and the excited state, and use this for tuning of transition dipole moments between particular spin levels. We also identify a role for relaxation via intersystem crossing. Building on these results, we demonstrate coherent population trapping -a key effect for quantum state transfer between spins and photons- for divacancy sub-ensembles along particular crystal axes. These results, combined with the flexibility of SiC polytypes and device processing, put SiC at the forefront of quantum information science in the solid state.

Quantum cascade lasers as metrological tools for space optics

NASA Astrophysics Data System (ADS)

Bartalini, S.; Borri, S.; Galli, I.; Mazzotti, D.; Cancio Pastor, P.; Giusfredi, G.; De Natale, P.

2017-11-01

A distributed-feedback quantum-cascade laser working in the 4.3÷4.4 mm range has been frequency stabilized to the Lamb-dip center of a CO2 ro-vibrational transition by means of first-derivative locking to the saturated absorption signal, and its absolute frequency counted with a kHz-level precision and an overall uncertainty of 75 kHz. This has been made possible by an optical link between the QCL and a near-IR Optical Frequency Comb Synthesizer, thanks to a non-linear sum-frequency generation process with a fiber-amplified Nd:YAG laser. The implementation of a new spectroscopic technique, known as polarization spectroscopy, provides an improved signal for the locking loop, and will lead to a narrower laser emission and a drastic improvement in the frequency stability, that in principle is limited only by the stability of the optical frequency comb synthesizer (few parts in 1013). These results confirm quantum cascade lasers as reliable sources not only for high-sensitivity, but also for highprecision measurements, ranking them as optimal laser sources for space applications.

Quantum Theory of Superresolution for Incoherent Optical Imaging

NASA Astrophysics Data System (ADS)

Tsang, Mankei

Rayleigh's criterion for resolving two incoherent point sources has been the most influential measure of optical imaging resolution for over a century. In the context of statistical image processing, violation of the criterion is especially detrimental to the estimation of the separation between the sources, and modern far-field superresolution techniques rely on suppressing the emission of close sources to enhance the localization precision. Using quantum optics, quantum metrology, and statistical analysis, here we show that, even if two close incoherent sources emit simultaneously, measurements with linear optics and photon counting can estimate their separation from the far field almost as precisely as conventional methods do for isolated sources, rendering Rayleigh's criterion irrelevant to the problem. Our results demonstrate that superresolution can be achieved not only for fluorophores but also for stars. Recent progress in generalizing our theory for multiple sources and spectroscopy will also be discussed. This work is supported by the Singapore National Research Foundation under NRF Grant No. NRF-NRFF2011-07 and the Singapore Ministry of Education Academic Research Fund Tier 1 Project R-263-000-C06-112.

Quantum Dots

NASA Astrophysics Data System (ADS)

Tartakovskii, Alexander

2012-07-01

Part I. Nanostructure Design and Structural Properties of Epitaxially Grown Quantum Dots and Nanowires: 1. Growth of III/V semiconductor quantum dots C. Schneider, S. Hofling and A. Forchel; 2. Single semiconductor quantum dots in nanowires: growth, optics, and devices M. E. Reimer, N. Akopian, M. Barkelid, G. Bulgarini, R. Heeres, M. Hocevar, B. J. Witek, E. Bakkers and V. Zwiller; 3. Atomic scale analysis of self-assembled quantum dots by cross-sectional scanning tunneling microscopy and atom probe tomography J. G. Keizer and P. M. Koenraad; Part II. Manipulation of Individual Quantum States in Quantum Dots Using Optical Techniques: 4. Studies of the hole spin in self-assembled quantum dots using optical techniques B. D. Gerardot and R. J. Warburton; 5. Resonance fluorescence from a single quantum dot A. N. Vamivakas, C. Matthiesen, Y. Zhao, C.-Y. Lu and M. Atature; 6. Coherent control of quantum dot excitons using ultra-fast optical techniques A. J. Ramsay and A. M. Fox; 7. Optical probing of holes in quantum dot molecules: structure, symmetry, and spin M. F. Doty and J. I. Climente; Part III. Optical Properties of Quantum Dots in Photonic Cavities and Plasmon-Coupled Dots: 8. Deterministic light-matter coupling using single quantum dots P. Senellart; 9. Quantum dots in photonic crystal cavities A. Faraon, D. Englund, I. Fushman, A. Majumdar and J. Vukovic; 10. Photon statistics in quantum dot micropillar emission M. Asmann and M. Bayer; 11. Nanoplasmonics with colloidal quantum dots V. Temnov and U. Woggon; Part IV. Quantum Dot Nano-Laboratory: Magnetic Ions and Nuclear Spins in a Dot: 12. Dynamics and optical control of an individual Mn spin in a quantum dot L. Besombes, C. Le Gall, H. Boukari and H. Mariette; 13. Optical spectroscopy of InAs/GaAs quantum dots doped with a single Mn atom O. Krebs and A. Lemaitre; 14. Nuclear spin effects in quantum dot optics B. Urbaszek, B. Eble, T. Amand and X. Marie; Part V. Electron Transport in Quantum Dots Fabricated by Lithographic Techniques: III-V Semiconductors and Carbon: 15. Electrically controlling single spin coherence in semiconductor nanostructures Y. Dovzhenko, K. Wang, M. D. Schroer and J. R. Petta; 16. Theory of electron and nuclear spins in III-V semiconductor and carbon-based dots H. Ribeiro and G. Burkard; 17. Graphene quantum dots: transport experiments and local imaging S. Schnez, J. Guettinger, F. Molitor, C. Stampfer, M. Huefner, T. Ihn and K. Ensslin; Part VI. Single Dots for Future Telecommunications Applications: 18. Electrically operated entangled light sources based on quantum dots R. M. Stevenson, A. J. Bennett and A. J. Shields; 19. Deterministic single quantum dot cavities at telecommunication wavelengths D. Dalacu, K. Mnaymneh, J. Lapointe, G. C. Aers, P. J. Poole, R. L. Williams and S. Hughes; Index.

Multiphoton Process and Anomalous Potential of Cell Membrane by Laser Radiation

NASA Technical Reports Server (NTRS)

Zhang, Kaixi; Zhao, Qingxun; Cui, Zhiyun; Zhar, Ping; Dong, Lifang

1996-01-01

In this paper, by the use of quantum biology and quantum optics, the laser induced potential variation of cell membrane has been studied. Theoretically, we have found a method of calculating the monophoton and multiphoton processes in the formation of the anomalous potential of cell membrane. In contrast with the experimental results, our numerical result is in the same order. Therefore, we have found the possibility of cancer caused by the laser induced anomalous cell potential.

Multitime correlation functions in nonclassical stochastic processes

NASA Astrophysics Data System (ADS)

Krumm, F.; Sperling, J.; Vogel, W.

2016-06-01

A general method is introduced for verifying multitime quantum correlations through the characteristic function of the time-dependent P functional that generalizes the Glauber-Sudarshan P function. Quantum correlation criteria are derived which identify quantum effects for an arbitrary number of points in time. The Magnus expansion is used to visualize the impact of the required time ordering, which becomes crucial in situations when the interaction problem is explicitly time dependent. We show that the latter affects the multi-time-characteristic function and, therefore, the temporal evolution of the nonclassicality. As an example, we apply our technique to an optical parametric process with a frequency mismatch. The resulting two-time-characteristic function yields full insight into the two-time quantum correlation properties of such a system.

Models of optical quantum computing

NASA Astrophysics Data System (ADS)

Krovi, Hari

2017-03-01

I review some work on models of quantum computing, optical implementations of these models, as well as the associated computational power. In particular, we discuss the circuit model and cluster state implementations using quantum optics with various encodings such as dual rail encoding, Gottesman-Kitaev-Preskill encoding, and coherent state encoding. Then we discuss intermediate models of optical computing such as boson sampling and its variants. Finally, we review some recent work in optical implementations of adiabatic quantum computing and analog optical computing. We also provide a brief description of the relevant aspects from complexity theory needed to understand the results surveyed.

Integrated generation of complex optical quantum states and their coherent control

NASA Astrophysics Data System (ADS)

Roztocki, Piotr; Kues, Michael; Reimer, Christian; Romero Cortés, Luis; Sciara, Stefania; Wetzel, Benjamin; Zhang, Yanbing; Cino, Alfonso; Chu, Sai T.; Little, Brent E.; Moss, David J.; Caspani, Lucia; Azaña, José; Morandotti, Roberto

2018-01-01

Complex optical quantum states based on entangled photons are essential for investigations of fundamental physics and are the heart of applications in quantum information science. Recently, integrated photonics has become a leading platform for the compact, cost-efficient, and stable generation and processing of optical quantum states. However, onchip sources are currently limited to basic two-dimensional (qubit) two-photon states, whereas scaling the state complexity requires access to states composed of several (<2) photons and/or exhibiting high photon dimensionality. Here we show that the use of integrated frequency combs (on-chip light sources with a broad spectrum of evenly-spaced frequency modes) based on high-Q nonlinear microring resonators can provide solutions for such scalable complex quantum state sources. In particular, by using spontaneous four-wave mixing within the resonators, we demonstrate the generation of bi- and multi-photon entangled qubit states over a broad comb of channels spanning the S, C, and L telecommunications bands, and control these states coherently to perform quantum interference measurements and state tomography. Furthermore, we demonstrate the on-chip generation of entangled high-dimensional (quDit) states, where the photons are created in a coherent superposition of multiple pure frequency modes. Specifically, we confirm the realization of a quantum system with at least one hundred dimensions. Moreover, using off-the-shelf telecommunications components, we introduce a platform for the coherent manipulation and control of frequencyentangled quDit states. Our results suggest that microcavity-based entangled photon state generation and the coherent control of states using accessible telecommunications infrastructure introduce a powerful and scalable platform for quantum information science.

Engineering quantum communication systems

NASA Astrophysics Data System (ADS)

Pinto, Armando N.; Almeida, Álvaro J.; Silva, Nuno A.; Muga, Nelson J.; Martins, Luis M.

2012-06-01

Quantum communications can provide almost perfect security through the use of quantum laws to detect any possible leak of information. We discuss critical issues in the implementation of quantum communication systems over installed optical fibers. We use stimulated four-wave mixing to generate single photons inside optical fibers, and by tuning the separation between the pump and the signal we adjust the average number of photons per pulse. We report measurements of the source statistics and show that it goes from a thermal to Poisson distribution with the increase of the pump power. We generate entangled photons pairs through spontaneous four-wave mixing. We report results for different type of fibers to approach the maximum value of the Bell inequality. We model the impact of polarization rotation, attenuation and Raman scattering and present optimum configurations to increase the degree of entanglement. We encode information in the photons polarization and assess the use of wavelength and time division multiplexing based control systems to compensate for the random rotation of the polarization during transmission. We show that time division multiplexing systems provide a more robust solution considering the values of PMD of nowadays installed fibers. We evaluate the impact on the quantum channel of co-propagating classical channels, and present guidelines for adding quantum channels to installed WDM optical communication systems without strongly penalizing the performance of the quantum channel. We discuss the process of retrieving information from the photons polarization. We identify the major impairments that limit the speed and distance of the quantum channel. Finally, we model theoretically the QBER and present results of an experimental performance assessment of the system quality through QBER measurements.

Experimental quantum information processing with the Talbot effect

NASA Astrophysics Data System (ADS)

Sawada, K.; Walborn, S. P.

2018-07-01

We report a proof of concept experiment illustrating the implementation of several simple quantum logic gates on D-level quantum systems (quDits) using the Talbot effect. A number of QuDit states are encoded into the transverse profile of a paraxial laser beam using a spatial light modulator. These states are transformed through a diagonal phase element and then free-propagation via the fractional Talbot effect, demonstrating the realization of some well-known single quDit gates in quantum computation. Our classical optics experiment allows us to identify several important technical details, and serves as a first experimental step in performing D-dimensional quantum operations with single photons or other quantum systems using this scheme.

Experimental demonstration of a quantum router

PubMed Central

Yuan, X. X.; Ma, J.-J.; Hou, P.-Y.; Chang, X.-Y.; Zu, C.; Duan, L.-M.

2015-01-01

The router is a key element for a network. We describe a scheme to realize genuine quantum routing of single-photon pulses based on cascading of conditional quantum gates in a Mach-Zehnder interferometer and report a proof-of-principle experiment for its demonstration using linear optics quantum gates. The polarization of the control photon routes in a coherent way the path of the signal photon while preserving the qubit state of the signal photon represented by its polarization. We demonstrate quantum nature of this router by showing entanglement generated between the initially unentangled control and signal photons, and confirm that the qubit state of the signal photon is well preserved by the router through quantum process tomography. PMID:26197928

Non-classical light generated by quantum-noise-driven cavity optomechanics.

PubMed

Brooks, Daniel W C; Botter, Thierry; Schreppler, Sydney; Purdy, Thomas P; Brahms, Nathan; Stamper-Kurn, Dan M

2012-08-23

Optomechanical systems, in which light drives and is affected by the motion of a massive object, will comprise a new framework for nonlinear quantum optics, with applications ranging from the storage and transduction of quantum information to enhanced detection sensitivity in gravitational wave detectors. However, quantum optical effects in optomechanical systems have remained obscure, because their detection requires the object’s motion to be dominated by vacuum fluctuations in the optical radiation pressure; so far, direct observations have been stymied by technical and thermal noise. Here we report an implementation of cavity optomechanics using ultracold atoms in which the collective atomic motion is dominantly driven by quantum fluctuations in radiation pressure. The back-action of this motion onto the cavity light field produces ponderomotive squeezing. We detect this quantum phenomenon by measuring sub-shot-noise optical squeezing. Furthermore, the system acts as a low-power, high-gain, nonlinear parametric amplifier for optical fluctuations, demonstrating a gain of 20 dB with a pump corresponding to an average of only seven intracavity photons. These findings may pave the way for low-power quantum optical devices, surpassing quantum limits on position and force sensing, and the control and measurement of motion in quantum gases.

Quantum Yield Heterogeneity among Single Nonblinking Quantum Dots Revealed by Atomic Structure-Quantum Optics Correlation

DOE PAGES

Orfield, Noah J.; McBride, James R.; Wang, Feng; ...

2016-02-05

Physical variations in colloidal nanostructures give rise to heterogeneity in expressed optical behavior. This correlation between nanoscale structure and function demands interrogation of both atomic structure and photophysics at the level of single nanostructures to be fully understood. In this paper, by conducting detailed analyses of fine atomic structure, chemical composition, and time-resolved single-photon photoluminescence data for the same individual nanocrystals, we reveal inhomogeneity in the quantum yields of single nonblinking “giant” CdSe/CdS core/shell quantum dots (g-QDs). We find that each g-QD possesses distinctive single exciton and biexciton quantum yields that result mainly from variations in the degree of charging,more » rather than from volume or structure inhomogeneity. We further establish that there is a very limited nonemissive “dark” fraction (<2%) among the studied g-QDs and present direct evidence that the g-QD core must lack inorganic passivation for the g-QD to be “dark”. Finally and therefore, in contrast to conventional QDs, ensemble photoluminescence quantum yield is principally defined by charging processes rather than the existence of dark g-QDs.« less

Exciton and intracenter radiative recombination in ZnMnTe and CdMnTe quantum wells with optically active manganese ions

NASA Astrophysics Data System (ADS)

Agekyan, V. F.; Akai, I.; Vasil'Ev, N. N.; Karasawa, T.; Karczewski, G.; Serov, A. Yu.; Filosofov, N. G.

2007-06-01

The emission spectra of Zn1-x Mn x Te/Zn0.6Mg0.4Te and Cd1-x Mn x Te/Cd0.5Mg0.5Te quantum-well structures with different manganese concentrations and quantum-well widths are studied at excitation power densities ranging from 105 to 107 W cm-2. Under strong optical pumping, intracenter luminescence of Mn2+ ions degrades as a result of the interaction of excited managanese ions with high-density excitons. This process is accompanied by a strong broadening of the emission band of quantum-well excitons due to the exciton-exciton interaction and saturation of the exciton ground state. Under pumping at a power density of 105 W cm-2, stimulated emission of quantum-well excitons arises in CdTe/Cd0.5Mg0.5Te. The luminescence kinetics of the quantum-well and barrier excitons is investigated with a high temporal resolution. The effect of the quantum-well width and the managanese concentration on the kinetics and band shape of the Mn2+ intracenter luminescence characterized by the contribution of the manganese interface ions is determined.

PREFACE: XVIII International Youth Scientific School "Coherent Optics and Optical Spectroscopy"

NASA Astrophysics Data System (ADS)

Salakhov, M. Kh; Samartsev, V. V.; Gainutdinov, R. Kh

2015-05-01

Kazan Federal University has held the annual International Youth School "Coherent Optics and Optical Spectroscopy" since 1997. The choice of the topic is not accidental. Kazan is the home of photon echo which was predicted at Kazan Physical-Technical Institute in 1963 by Prof. U.G. Kopvil'em and V.R. Nagibarov and observed in Columbia University by N.A. Kurnit, I.D. Abella, and S.R. Hartmann in 1964. Since then, photon echo has become a powerful tool of coherent optical spectroscopy and optical information processing, which have been developed here in Kazan in close collaboration between Kazan Physical-Technical Institute and Kazan Federal University. The main subjects of the XVIII International Youth School are: Nonlinear and coherent optics; Atomic and molecular spectroscopy; Coherent laser spectroscopy; Problems of quantum optics; Quantum theory of radiation; and Nanophotonics and Scanning Probe Microscopy. The unchallenged organizers of that school are Kazan Federal University and Kazan E.K. Zavoisky Physical-Technical Institute. The rector of the School is Professor Myakzyum Salakhov, and the vice-rector is Professor Vitaly Samartsev. The International Youth Scientific School "Coherent Optics and Optical Spectroscopy" follows the global pattern of comprehensive studies of matter properties and their interaction with electromagnetic fields. Since 1997 more than 100 famous scientists from the USA, Germany, Ukraine, Belarus and Russia have given plenary lecture presentations. Here over 1000 young scientists had an opportunity to participate in lively discussions about the latest scientific news. Many young people have submitted interesting reports on photonics, quantum electronics, laser physics, quantum optics, traditional optical and laser spectroscopy, non-linear optics, material science and nanotechnology. Here we are publishing the fullsize papers prepared from the most interesting lectures and reports selected by the Program Committee of the School. The International Youth Scientific School "Coherent Optics and Optical Spectroscopy" was greatly supported by The Optical Society of America, the Russian Foundation for Basic Research, the non-profit Dynasty Foundation, the Tatarstan Academy of Science, and the Ministry of Education and Science of the Russian Federation. It is a pleasure to thank the sponsors and all the participants and contributors who made the International School meeting possible and interesting.

Phonon counting and intensity interferometry of a nanomechanical resonator

NASA Astrophysics Data System (ADS)

Cohen, Justin D.; Meenehan, Seán M.; Maccabe, Gregory S.; Gröblacher, Simon; Safavi-Naeini, Amir H.; Marsili, Francesco; Shaw, Matthew D.; Painter, Oskar

2015-04-01

In optics, the ability to measure individual quanta of light (photons) enables a great many applications, ranging from dynamic imaging within living organisms to secure quantum communication. Pioneering photon counting experiments, such as the intensity interferometry performed by Hanbury Brown and Twiss to measure the angular width of visible stars, have played a critical role in our understanding of the full quantum nature of light. As with matter at the atomic scale, the laws of quantum mechanics also govern the properties of macroscopic mechanical objects, providing fundamental quantum limits to the sensitivity of mechanical sensors and transducers. Current research in cavity optomechanics seeks to use light to explore the quantum properties of mechanical systems ranging in size from kilogram-mass mirrors to nanoscale membranes, as well as to develop technologies for precision sensing and quantum information processing. Here we use an optical probe and single-photon detection to study the acoustic emission and absorption processes in a silicon nanomechanical resonator, and perform a measurement similar to that used by Hanbury Brown and Twiss to measure correlations in the emitted phonons as the resonator undergoes a parametric instability formally equivalent to that of a laser. Owing to the cavity-enhanced coupling of light with mechanical motion, this effective phonon counting technique has a noise equivalent phonon sensitivity of 0.89 +/- 0.05. With straightforward improvements to this method, a variety of quantum state engineering tasks using mesoscopic mechanical resonators would be enabled, including the generation and heralding of single-phonon Fock states and the quantum entanglement of remote mechanical elements.

Optical gain for the interband optical transition in InAsP/InP quantum well wire in the influence of laser field intensity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saravanan, S.; Peter, A. John, E-mail: a.john.peter@gmail.com

Intense high frequency laser field induced electronic and optical properties of heavy hole exciton in the InAs{sub 0.8}P{sub 0.2}/InP quantum wire is studied taking into account the geometrical confinement effect. Laser field related exciton binding energies and the optical band gap in the InAs{sub 0.8}P{sub 0.2}/InP quantum well wire are investigated. The optical gain, for the interband optical transition, as a function of photon energy, in the InAs{sub 0.8}P{sub 0.2}/InP quantum wire, is obtained in the presence of intense laser field. The compact density matrix method is employed to obtain the optical gain. The obtained optical gain in group III-Vmore » narrow quantum wire can be applied for achieving the preferred telecommunication wavelength.« less

Observable measure of quantum coherence in finite dimensional systems.

PubMed

Girolami, Davide

2014-10-24

Quantum coherence is the key resource for quantum technology, with applications in quantum optics, information processing, metrology, and cryptography. Yet, there is no universally efficient method for quantifying coherence either in theoretical or in experimental practice. I introduce a framework for measuring quantum coherence in finite dimensional systems. I define a theoretical measure which satisfies the reliability criteria established in the context of quantum resource theories. Then, I present an experimental scheme implementable with current technology which evaluates the quantum coherence of an unknown state of a d-dimensional system by performing two programmable measurements on an ancillary qubit, in place of the O(d2) direct measurements required by full state reconstruction. The result yields a benchmark for monitoring quantum effects in complex systems, e.g., certifying nonclassicality in quantum protocols and probing the quantum behavior of biological complexes.

Quantum Optics in Astrophysics: The Potential of a New Window

NASA Astrophysics Data System (ADS)

Solomos, Nikolaos H.

2006-08-01

The entire optical astronomy relies upon the detection of light. In this contribution, we put emphasis to the fact that a new window to the universe could be opened with the obvious idea of applying the ...Quantum Theory to describe incoming light Quanta (!). It is clearly the appropriate approach but, nevertheless, it never deemed necessary in main stream astrophysics: Customarily, traditional astronomy not only prefers time-averaged quantities, (although fluctuations in time of a measurement can be a source of information which is getting entirely lost in any time-averaged value) but misses much more information content by continuing to use old semi-classical approaches to treat photon detection processes. Thus, we fail to describe and appreciate in full very important properties of cosmic light, like spatiotemporal coherence. Nevertheless, 45 years of knowledge accumulation in Quantum Optics and technology can now result to the development of instruments capable to extract intimate quantum information scrambled in the incoming optical light fields from celestial sources, provided their ability to detect light emission alterations in the

Collision models in quantum optics

NASA Astrophysics Data System (ADS)

Ciccarello, Francesco

2017-12-01

Quantum collision models (CMs) provide advantageous case studies for investigating major issues in open quantum systems theory, and especially quantum non-Markovianity. After reviewing their general definition and distinctive features, we illustrate the emergence of a CM in a familiar quantum optics scenario. This task is carried out by highlighting the close connection between the well-known input-output formalism and CMs. Within this quantum optics framework, usual assumptions in the CMs' literature - such as considering a bath of noninteracting yet initially correlated ancillas - have a clear physical origin.

Compact sub-kilohertz low-frequency quantum light source based on four-wave mixing in cesium vapor

NASA Astrophysics Data System (ADS)

Ma, Rong; Liu, Wei; Qin, Zhongzhong; Su, Xiaolong; Jia, Xiaojun; Zhang, Junxiang; Gao, Jiangrui

2018-03-01

Using a nondegenerate four-wave mixing (FWM) process based on a double-{\\Lambda} scheme in hot cesium vapor, we demonstrate a compact diode-laser-pumped quantum light source for the generation of quantum correlated twin beams with a maximum squeezing of 6.5 dB. The squeezing is observed at a Fourier frequency in the audio band down to 0.7 kHz which, to the best of our knowledge, is the first observation of sub-kilohertz intensity-difference squeezing in an atomic system so far. A phase-matching condition is also investigated in our system, which confirms the spatial-multi-mode characteristics of the FWM process. Our compact low-frequency squeezed light source may find applications in quantum imaging, quantum metrology, and the transfer of optical squeezing onto a matter wave.

Optical communication with two-photon coherent states. II - Photoemissive detection and structured receiver performance

NASA Technical Reports Server (NTRS)

Shapiro, J. H.; Yuen, H. P.; Machado Mata, J. A.

1979-01-01

In a previous paper (1978), the authors developed a method of analyzing the performance of two-photon coherent state (TCS) systems for free-space optical communications. General theorems permitting application of classical point process results to detection and estimation of signals in arbitrary quantum states were derived. The present paper examines the general problem of photoemissive detection statistics. On the basis of the photocounting theory of Kelley and Kleiner (1964) it is shown that for arbitrary pure state illumination, the resulting photocurrent is in general a self-exciting point process. The photocount statistics for first-order coherent fields reduce to those of a special class of Markov birth processes, which the authors term single-mode birth processes. These general results are applied to the structure of TCS radiation, and it is shown that the use of TCS radiation with direct or heterodyne detection results in minimal performance increments over comparable coherent-state systems. However, significant performance advantages are offered by use of TCS radiation with homodyne detection. The abstract quantum descriptions of homodyne and heterodyne detection are derived and a synthesis procedure for obtaining quantum measurements described by arbitrary TCS is given.

Scalable quantum information processing with photons and atoms

NASA Astrophysics Data System (ADS)

Pan, Jian-Wei

Over the past three decades, the promises of super-fast quantum computing and secure quantum cryptography have spurred a world-wide interest in quantum information, generating fascinating quantum technologies for coherent manipulation of individual quantum systems. However, the distance of fiber-based quantum communications is limited due to intrinsic fiber loss and decreasing of entanglement quality. Moreover, probabilistic single-photon source and entanglement source demand exponentially increased overheads for scalable quantum information processing. To overcome these problems, we are taking two paths in parallel: quantum repeaters and through satellite. We used the decoy-state QKD protocol to close the loophole of imperfect photon source, and used the measurement-device-independent QKD protocol to close the loophole of imperfect photon detectors--two main loopholes in quantum cryptograph. Based on these techniques, we are now building world's biggest quantum secure communication backbone, from Beijing to Shanghai, with a distance exceeding 2000 km. Meanwhile, we are developing practically useful quantum repeaters that combine entanglement swapping, entanglement purification, and quantum memory for the ultra-long distance quantum communication. The second line is satellite-based global quantum communication, taking advantage of the negligible photon loss and decoherence in the atmosphere. We realized teleportation and entanglement distribution over 100 km, and later on a rapidly moving platform. We are also making efforts toward the generation of multiphoton entanglement and its use in teleportation of multiple properties of a single quantum particle, topological error correction, quantum algorithms for solving systems of linear equations and machine learning. Finally, I will talk about our recent experiments on quantum simulations on ultracold atoms. On the one hand, by applying an optical Raman lattice technique, we realized a two-dimensional spin-obit (SO) coupling and topological bands with ultracold bosonic atoms. A controllable crossover between 2D and 1D SO couplings is studied, and the SO effects and nontrivial band topology are observe. On the other hand, utilizing a two-dimensional spin-dependent optical superlattice and a single layer of atom cloud, we directly observed the four-body ring-exchange coupling and the Anyonic fractional statistics.

A universal quantum module for quantum communication, computation, and metrology

NASA Astrophysics Data System (ADS)

Hanks, Michael; Lo Piparo, Nicolò; Trupke, Michael; Schmiedmayer, Jorg; Munro, William J.; Nemoto, Kae

2017-08-01

In this work, we describe a simple module that could be ubiquitous for quantum information based applications. The basic modules comprises a single NV- center in diamond embedded in an optical cavity, where the cavity mediates interactions between photons and the electron spin (enabling entanglement distribution and efficient readout), while the nuclear spins constitutes a long-lived quantum memories capable of storing and processing quantum information. We discuss how a network of connected modules can be used for distributed metrology, communication and computation applications. Finally, we investigate the possible use of alternative diamond centers (SiV/GeV) within the module and illustrate potential advantages.

EDITORIAL The 17th Central European Workshop on Quantum Optics

NASA Astrophysics Data System (ADS)

Man'ko, Margarita A.

2011-02-01

Although the origin of quantum optics can be traced back to the beginning of the 20th century, when the fundamental ideas about the quantum nature of the interaction between light and matter were put forward, the splendid blossoming of this part of physics began half a century later, after the invention of masers and lasers. It is remarkable that after another half a century the tree of quantum optics is not only very strong and spreading, but all its branches continue to grow, showing new beautiful blossoms and giving very useful fruits. A reflection of this progress has been the origin and development of the series of annual events called the Central European Workshops on Quantum Optics (CEWQO). They started at the beginning of the 1990s as rather small meetings of physicists from a few countries in central-eastern Europe, but in less than two decades they have transformed into important events, gathering 100 to 200 participants from practically all European countries. Moreover, many specialists from other continents like to attend these meetings, since they provide an excellent chance to hear about the latest results and new directions of research. Regarding this, it seems worth mentioning at least some of the most interesting and important areas of quantum optics that have attracted the attention of researchers for the past two decades. One of these areas is quantum information, which over the course of time has become an almost independent area of quantum physics. But it still maintains very close ties with quantum optics. The specific parts of this area are, in particular, quantum computing, quantum communication and quantum cryptography, and the problem of quantitative description of such genuine quantum phenomena as entanglement is one of the central items in the current stream of publications. Theory and experiment related to quantum tomography have also become important to contemporary quantum optics. They are closely related to the subject of so-called quantum-state engineering. Different schemes proposed within the framework of this new area enabled the creation in laboratories of various superpositions of quantum states which had previously existed only as beautiful mathematical constructions by theoreticians. Connected to this, recent experiments related to such old problems as decoherence and quantum-classical transition are quite impressive. The same can be said about the interrelations between quantum optics and physics of ultracold atoms and Bose-Einstein condensates. Great progress has been made in cavity quantum electrodynamics, and the past decade gave rise to the new area of circuit quantum electrodynamics. Nowadays, we are very close to the observation of the quantum behavior of macroscopic bodies (mirrors), and the methods used in quantum optics help to achieve this goal. Quantum optics over the past two decades has resulted in such impressive discoveries as the slowing down of light to extremely low velocities and the creation of photonic crystals. The new methods of achieving very strong coupling coefficients between quantized field modes and atomic degrees of freedom open new possibilities for storing and retrieving quantum information transmitted by light. New areas of terahertz, femto- and atto-second optics were born or were significantly developed during the past two decades. In addition, the tomographic-probability representation of photon-quantum states has created new possibilities both in theoretical and experimental aspects of quantum optics. Traditionally, measured optical tomograms of photon states were considered as a technical tool for reconstructing the Wigner functions of quantum states. It became clear that these measured tomograms are primary objects; one does not need to reconstruct the Wigner function to extract information on physical properties of the state, for example, on the state purity. Purity is experimentally obtained directly from measured optical tomograms of photon states. The uncertainty relations for photon quadratures were also checked for the thermal photon state using experimental values of optical tomograms and avoiding the reconstruction procedure of the Wigner function and its associated precision constrains. In the tomographic-probability representation of quantum mechanics and quantum optics, tomograms are used for the description of quantum states as an alternative to the wave function and density matrix. The purity, fidelity, entropy and photon temperature associated with quantum states are expressed in terms of tomograms. This provides the possibility of measuring these characteristics directly by taking optical tomograms and checking basic inequalities like entropic uncertainty relations, temperature-dependent quadrature uncertainty relations, etc. The better understanding that quantum states can be identified with measurable probability distributions like optical tomograms opens new prospects in quantum optics, for example, to check experimentally the uncertainty relations for higher quadrature momenta and to control the precision with which the fundamental inequalities of quantum mechanics are experimentally confirmed. This Topical Issue is a collection of papers presented at the 17th Central European Workshops on Quantum Optics (CEWQO10) held at the University of St Andrews, Scotland, UK, 6-11 June 2010. The other collaborators from different scientific centers who could not, due to different reasons, come to St Andrews but participated in the previous CEWQOs and plan to participate in future CEWQOs also contributed to this issue. The paper by Ulf Leonhardt and Natalia Korolkova, the CEWQO10 Organizers, opens this issue. The order of the following papers corresponds to the alphabetical order of the first author of the paper. The history of CEWQOs can be found in the Preface to the Proceedings of the 15th CEWQO (2009 Phys. Scr. T135 011005). The Proceedings of the 16th Central European Workshop on Quantum Optics (CEWQO09), held at the University of Turku, are also available (2010 Phys. Scr. T140). The 18th Central European Workshop on Quantum Optics (CEWQO11) will be held in Madrid, Spain on 30 May--3 June 2011. It will be chaired by Professor Luis Lorenzo Sanchez Soto from the Complutense University of Madrid. List of Papers The 17th Central European Workshop on Quantum Optics in St Andrews, Scotland Ulf Leonhardt and Natalia Korolkova Double self-Kerr scheme for optical Schrödinger-cat state preparation P Adam, Z Darázs, T Kiss and M Mechler Relations between scaling transformed Husimi functions, Wigner functions and symplectic tomograms describing corresponding physical states V A Andreev, D M Davidović, L D Davidović and M D Davidović Entanglement dynamics of two independent cavity-embedded quantum dots B Bellomo, G Compagno, R Lo Franco, A Ridolfo and S Savasta Dynamical stabilization of spin systems in time-dependent magnetic fields Yu V Bezvershenko, P I Holod and A Messina Entanglement dynamics of a bipartite system in squeezed vacuum reservoirs Smail Bougouffa and Awatif Hindi On Wheeler's delayed-choice Gedankenexperiment and its laboratory realization M Božić, L Vušković, M Davidović and Á S Sanz A smooth, holographically generated ring trap for the investigation of superfluidity in ultracold atoms Graham D Bruce, James Mayoh, Giuseppe Smirne, Lara Torralbo-Campo and Donatella Cassettari Parametric amplification of the classical field in cavities with photoexcited semiconductors V V Dodonov Mutually unbiased bases: tomography of spin states and the star-product scheme S N Filippov and V I Man'ko Quantum trajectory model for photon detectors and optoelectronic devices Teppo Häyrynen, Jani Oksanen and Jukka Tulkki Entanglement in two-mode continuous variable open quantum systems Aurelian Isar A classical field comeback? The classical field viewpoint on triparticle entanglement Andrei Khrennikov Experimental investigation of the enhancement factor and the cross-correlation function for graphs with and without time-reversal symmetry: the open system case Michał Ławniczak, Szymon Bauch, Oleh Hul and Leszek Sirko Independent nonclassical tests for states and measurements in the same experiment Alfredo Luis and Ángel Rivas On the classical capacity of quantum Gaussian channels Cosmo Lupo, Stefano Pirandola, Paolo Aniello and Stefano Mancini Entropic inequalities for center-of-mass tomograms Margarita A Man'ko Semiclassical dynamics for an ion confined within a nonlinear electromagnetic trap Bogdan M Mihalcea Zeno-like phenomena in STIRAP processes B Militello, M Scala, A Messina and N V Vitanov A beam splitter with second-order nonlinearity modeled as a nonlinear coupler V Peřinová, A Lukš and J Křepelka Energy-level shifts of a uniformly accelerated atom between two reflecting plates L Rizzuto and S Spagnolo Cross-Kerr nonlinearities in an optically dressed periodic medium K Słowik, A Raczyński, J Zaremba, S Zielińska-Kaniasty, M Artoni and G C La Rocca An approximate effective beamsplitter interaction between light and atomic ensembles Richard Tatham, David Menzies and Natalia Korolkova Stochastic simulation of long-time nonadiabatic dynamics Daniel A Uken, Alessandro Sergi and Francesco Petruccione

Electromagnetic Saturation of Angstrom-Sized Quantum Barriers at Terahertz Frequencies

NASA Astrophysics Data System (ADS)

Bahk, Young-Mi; Kang, Bong Joo; Kim, Yong Seung; Kim, Joon-Yeon; Kim, Won Tae; Kim, Tae Yun; Kang, Taehee; Rhie, Jiyeah; Han, Sanghoon; Park, Cheol-Hwan; Rotermund, Fabian; Kim, Dai-Sik

2015-09-01

Metal-graphene-metal hybrid structures allow angstrom-scale van der Waals gaps, across which electron tunneling occurs. We squeeze terahertz electromagnetic waves through these λ /10 000 000 gaps, accompanied by giant field enhancements. Unprecedented transmission reduction of 97% is achieved with the transient voltage across the gap saturating at 5 V. Electron tunneling facilitated by the transient electric field strongly modifies the gap index, starting a self-limiting process related to the barrier height. Our work enables greater interplay between classical optics and quantum tunneling, and provides optical indices to the van der Waals gaps.

Decoherence processes during optical manipulation of excitonic qubits in semiconductor quantum dots

NASA Astrophysics Data System (ADS)

Wang, Q. Q.; Muller, A.; Bianucci, P.; Rossi, E.; Xue, Q. K.; Takagahara, T.; Piermarocchi, C.; MacDonald, A. H.; Shih, C. K.

2005-07-01

Using photoluminescence spectroscopy, we have investigated the nature of Rabi oscillation damping during optical manipulation of excitonic qubits in self-assembled quantum dots. Rabi oscillations were recorded by varying the pulse amplitude for fixed pulse durations between 4ps and 10ps . Up to five periods are visible, making it possible to quantify the excitation dependent damping. We find that this damping is more pronounced for shorter pulse widths and show that its origin is the nonresonant excitation of carriers in the wetting layer, most likely involving bound-to-continuum and continuum-to-bound transitions.

Optical Nonlinearities in GaAs/GaAlAs Multiple Quantum Wells Fabricated by Metalorganic Chemical Vapor Deposition for Use in Optical Signal Processing.

DTIC Science & Technology

1987-12-01

larger energy separation of the terminal states. The spectra of the thicker wells show peaks due to transitions from the n=2 and n=3 electron states. The...are found in the theses of H. C. Lee (PhD) and M. Kawase (MS). Section III contains an invited paper submittted to Journal of Quantum Electronics ...steps are associated with the allowed energies of the "square well potential" and are a strong function of the dimensions of the well and the

Electromagnetic Saturation of Angstrom-Sized Quantum Barriers at Terahertz Frequencies.

PubMed

Bahk, Young-Mi; Kang, Bong Joo; Kim, Yong Seung; Kim, Joon-Yeon; Kim, Won Tae; Kim, Tae Yun; Kang, Taehee; Rhie, Jiyeah; Han, Sanghoon; Park, Cheol-Hwan; Rotermund, Fabian; Kim, Dai-Sik

2015-09-18

Metal-graphene-metal hybrid structures allow angstrom-scale van der Waals gaps, across which electron tunneling occurs. We squeeze terahertz electromagnetic waves through these λ/10 000 000 gaps, accompanied by giant field enhancements. Unprecedented transmission reduction of 97% is achieved with the transient voltage across the gap saturating at 5 V. Electron tunneling facilitated by the transient electric field strongly modifies the gap index, starting a self-limiting process related to the barrier height. Our work enables greater interplay between classical optics and quantum tunneling, and provides optical indices to the van der Waals gaps.

A Scalable Microfabricated Ion Trap for Quantum Information Processing

NASA Astrophysics Data System (ADS)

Maunz, Peter; Haltli, Raymond; Hollowell, Andrew; Lobser, Daniel; Mizrahi, Jonathan; Rembetski, John; Resnick, Paul; Sterk, Jonathan D.; Stick, Daniel L.; Blain, Matthew G.

2016-05-01

Trapped Ion Quantum Information Processing (QIP) relies on complex microfabricated trap structures to enable scaling of the number of quantum bits. Building on previous demonstrations of surface-electrode ion traps, we have designed and characterized the Sandia high-optical-access (HOA-2) microfabricated ion trap. This trap features high optical access, high trap frequencies, low heating rates, and negligible charging of dielectric trap components. We have observed trap lifetimes of more than 100h, measured trap heating rates for ytterbium of less than 40quanta/s, and demonstrated shuttling of ions from a slotted to an above surface region and through a Y-junction. Furthermore, we summarize demonstrations of high-fidelity single and two-qubit gates realized in this trap. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000. This work was supported by the Intelligence Advanced Research Projects Activity (IARPA).

Highly Efficient Coherent Optical Memory Based on Electromagnetically Induced Transparency

NASA Astrophysics Data System (ADS)

Hsiao, Ya-Fen; Tsai, Pin-Ju; Chen, Hung-Shiue; Lin, Sheng-Xiang; Hung, Chih-Chiao; Lee, Chih-Hsi; Chen, Yi-Hsin; Chen, Yong-Fan; Yu, Ite A.; Chen, Ying-Cheng

2018-05-01

Quantum memory is an important component in the long-distance quantum communication based on the quantum repeater protocol. To outperform the direct transmission of photons with quantum repeaters, it is crucial to develop quantum memories with high fidelity, high efficiency and a long storage time. Here, we achieve a storage efficiency of 92.0 (1.5)% for a coherent optical memory based on the electromagnetically induced transparency scheme in optically dense cold atomic media. We also obtain a useful time-bandwidth product of 1200, considering only storage where the retrieval efficiency remains above 50%. Both are the best record to date in all kinds of schemes for the realization of optical memory. Our work significantly advances the pursuit of a high-performance optical memory and should have important applications in quantum information science.

Highly Efficient Coherent Optical Memory Based on Electromagnetically Induced Transparency.

PubMed

Hsiao, Ya-Fen; Tsai, Pin-Ju; Chen, Hung-Shiue; Lin, Sheng-Xiang; Hung, Chih-Chiao; Lee, Chih-Hsi; Chen, Yi-Hsin; Chen, Yong-Fan; Yu, Ite A; Chen, Ying-Cheng

2018-05-04

Quantum memory is an important component in the long-distance quantum communication based on the quantum repeater protocol. To outperform the direct transmission of photons with quantum repeaters, it is crucial to develop quantum memories with high fidelity, high efficiency and a long storage time. Here, we achieve a storage efficiency of 92.0 (1.5)% for a coherent optical memory based on the electromagnetically induced transparency scheme in optically dense cold atomic media. We also obtain a useful time-bandwidth product of 1200, considering only storage where the retrieval efficiency remains above 50%. Both are the best record to date in all kinds of schemes for the realization of optical memory. Our work significantly advances the pursuit of a high-performance optical memory and should have important applications in quantum information science.

Synthesis and characterization of graphene quantum dots-silver nanocomposites

NASA Astrophysics Data System (ADS)

Vandana, M.; Ashokkumar, S. P.; Vijeth, H.; Niranjana, M.; Yesappa, L.; Devendrappa, H.

2018-04-01

A facile microwave assisted hydrothermal method is used to synthesise glucose derived water soluble crystalline graphene quantum dots (GQDs) andcitrate reduction method was used to synthesized silver nanoparticles (SNPs). The formation of graphene quantum dots-silver nanocomposites (GSC) was synthesized through a simple refluxing process and characterised using Fourier Transform Infrared (FT-IR) to study the chemical interaction, Surface morphology using FESEM, Optical properties were studied using UV-Visible spectroscopy. The absorption band shows at 249, 306 and 447 nm confirms the formation of GQDs and GSC. The electrochemical performance of GSC tested to determine the oxidation/reduction processes by cyclic voltammetry and linear sweep voltammetry.

Quantum interference in heterogeneous superconducting-photonic circuits on a silicon chip

PubMed Central

Schuck, C.; Guo, X.; Fan, L.; Ma, X.; Poot, M.; Tang, H. X.

2016-01-01

Quantum information processing holds great promise for communicating and computing data efficiently. However, scaling current photonic implementation approaches to larger system size remains an outstanding challenge for realizing disruptive quantum technology. Two main ingredients of quantum information processors are quantum interference and single-photon detectors. Here we develop a hybrid superconducting-photonic circuit system to show how these elements can be combined in a scalable fashion on a silicon chip. We demonstrate the suitability of this approach for integrated quantum optics by interfering and detecting photon pairs directly on the chip with waveguide-coupled single-photon detectors. Using a directional coupler implemented with silicon nitride nanophotonic waveguides, we observe 97% interference visibility when measuring photon statistics with two monolithically integrated superconducting single-photon detectors. The photonic circuit and detector fabrication processes are compatible with standard semiconductor thin-film technology, making it possible to implement more complex and larger scale quantum photonic circuits on silicon chips. PMID:26792424

Empirical Analysis of Optical Attenuator Performance in Quantum Key Distribution Systems Using a Particle Model

DTIC Science & Technology

2012-03-01

EMPIRICAL ANALYSIS OF OPTICAL ATTENUATOR PERFORMANCE IN QUANTUM KEY DISTRIBUTION SYSTEMS USING A...DISTRIBUTION IS UNLIMITED AFIT/GCS/ENG/12-01 EMPIRICAL ANALYSIS OF OPTICAL ATTENUATOR PERFORMANCE IN QUANTUM KEY DISTRIBUTION SYSTEMS USING ...challenging as the complexity of actual implementation specifics are considered. Two components common to most quantum key distribution

Optical storage with electromagnetically induced transparency in cold atoms at a high optical depth

NASA Astrophysics Data System (ADS)

Zhang, Shanchao; Zhou, Shuyu; Liu, Chang; Chen, J. F.; Wen, Jianming; Loy, M. M. T.; Wong, G. K. L.; Du, Shengwang

2012-06-01

We report experimental demonstration of efficient optical storage with electromagnetically induced transparency (EIT) in a dense cold ^85Rb atomic ensemble trapped in a two-dimensional magneto-optical trap. By varying the optical depth (OD) from 0 to 140, we observe that the optimal storage efficiency for coherent optical pulses has a saturation value of 50% as OD > 50. Our result is consistent with that obtained from hot vapor cell experiments which suggest that a four-wave mixing nonlinear process degrades the EIT storage coherence and efficiency. We apply this EIT quantum memory for narrow-band single photons with controllable waveforms, and obtain an optimal storage efficiency of 49±3% for single-photon wave packets. This is the highest single-photon storage efficiency reported up to today and brings the EIT atomic quantum memory close to practical application because an efficiency of above 50% is necessary to operate the memory within non-cloning regime and beat the classical limit.

Stimulated electronic transition concept for an erasable optical memory

NASA Technical Reports Server (NTRS)

Albin, Sacharia; Satira, James D.; Livingston, David L.; Shull, Thomas A.

1992-01-01

A new concept for an erasable optical memory is demonstrated using stimulated electronic transition (SET). Large bandgap semiconductors are suitable materials for the SET medium. The properties of MgS:Eu,Sm and SrS:Eu,Sm as possible media for the SET process are investigated. Quantum storage is achieved in the form of charges in deep levels in the medium and stimulated radiative recombination is used as the reading process. Unlike magneto-optic (M-O) and phase change (PC) processes, optical writing, reading and erasing are achieved without localized heating. The SET process will have an inherently faster data transfer rate and a higher storage density, and the medium will be more durable than the M-O and PC media. A possible application of the SET process in neural networks is also discussed.

Noise reduction in optically controlled quantum memory

NASA Astrophysics Data System (ADS)

Ma, Lijun; Slattery, Oliver; Tang, Xiao

2018-05-01

Quantum memory is an essential tool for quantum communications systems and quantum computers. An important category of quantum memory, called optically controlled quantum memory, uses a strong classical beam to control the storage and re-emission of a single-photon signal through an atomic ensemble. In this type of memory, the residual light from the strong classical control beam can cause severe noise and degrade the system performance significantly. Efficiently suppressing this noise is a requirement for the successful implementation of optically controlled quantum memories. In this paper, we briefly introduce the latest and most common approaches to quantum memory and review the various noise-reduction techniques used in implementing them.

Plasmonic Control of Radiation and Absorption Processes in Semiconductor Quantum Dots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paiella, Roberto; Moustakas, Theodore D.

This document reviews a research program funded by the DOE Office of Science, which has been focused on the control of radiation and absorption processes in semiconductor photonic materials (including III-nitride quantum wells and quantum dots), through the use of specially designed metallic nanoparticles (NPs). By virtue of their strongly confined plasmonic resonances (i.e., collective oscillations of the electron gas), these nanostructures can concentrate incident radiation into sub-wavelength “hot spots” of highly enhanced field intensity, thereby increasing optical absorption by suitably positioned absorbers. By reciprocity, the same NPs can also dramatically increase the spontaneous emission rate of radiating dipoles locatedmore » within their hot spots. The NPs can therefore be used as optical antennas to enhance the radiation output of the underlying active material and at the same time control the far-field pattern of the emitted light. The key accomplishments of the project include the demonstration of highly enhanced light emission efficiency as well as plasmonic collimation and beaming along geometrically tunable directions, using a variety of plasmonic excitations. Initial results showing the reverse functionality (i.e., plasmonic unidirectional absorption and photodetection) have also been generated with similar systems. Furthermore, a new paradigm for the near-field control of light emission has been introduced through rigorous theoretical studies, based on the use of gradient metasurfaces (i.e., optical nanoantenna arrays with spatially varying shape, size, and/or orientation). These activities have been complemented by materials development efforts aimed at the synthesis of suitable light-emitting samples by molecular beam epitaxy. In the course of these efforts, a novel technique for the growth of III-nitride quantum dots has also been developed (droplet heteroepitaxy), with several potential advantages in terms of compositional and geometrical control. The results of these studies provide fundamental new understanding of optical processes at the nanoscale, including near-field energy transfer between quantum emitters and photonic nanostructures, dissipation phenomena of plasmonic excitations, and radiation from nanoantennas. Furthermore, they may open the way to entirely new device concepts and applications, in a broad range of disciplines including optoelectronics, sensing, spectroscopy, photovoltaics, and quantum information science. A specific application of particularly strong relevance to the DOE mission is the development of energy efficient LED active materials for solid-state lighting, based on plasmonic enhancement effects.« less

Spins and photons: connecting quantum registers in diamond

NASA Astrophysics Data System (ADS)

Childress, Lily

2012-06-01

Long-lived electronic and nuclear spin states have made the nitrogen-vacancy (NV) defect in diamond a leading candidate for quantum information processing in the solid state. Multi-qubit quantum registers formed by single defects and nearby nuclear spins can currently be controlled and detected with high fidelity. Nevertheless, development of coherent connections between distant NVs remains an outstanding challenge. One advantage to working with solid-state defects is the opportunity to integrate them with microfabricated mechanical, electronic, or optical devices; in principle, such devices could mediate interactions between registers, turning them into nodes within a larger quantum network. In the last few months, several experiments have made key steps toward realizing a coherent quantum interface between individual NV centers using a mechanical quantum bus [1] or optical channels [2,3]. This talk will explore the current state of the art, and report on recent observation of two photon quantum interference between different gate-tunable defect centers [2]. These results pave the way towards measurement-based entanglement between remote NV centers and the realization of quantum networks with solid-state spins.[4pt] [1] Kolkowitz et al., Science 335, 1603 (2012)[2] Bernien et al., Phys. Rev. Lett. 108, 043604 (2012)[3] Sipahigil et al., http://lanl.arxiv.org/abs/1112.3975

Transfer of non-Gaussian quantum states of mechanical oscillator to light

NASA Astrophysics Data System (ADS)

Filip, Radim; Rakhubovsky, Andrey A.

2015-11-01

Non-Gaussian quantum states are key resources for quantum optics with continuous-variable oscillators. The non-Gaussian states can be deterministically prepared by a continuous evolution of the mechanical oscillator isolated in a nonlinear potential. We propose feasible and deterministic transfer of non-Gaussian quantum states of mechanical oscillators to a traveling light beam, using purely all-optical methods. The method relies on only basic feasible and high-quality elements of quantum optics: squeezed states of light, linear optics, homodyne detection, and electro-optical feedforward control of light. By this method, a wide range of novel non-Gaussian states of light can be produced in the future from the mechanical states of levitating particles in optical tweezers, including states necessary for the implementation of an important cubic phase gate.

Universal Behavior of Quantum Spin Liquid and Optical Conductivity in the Insulator Herbertsmithite

NASA Astrophysics Data System (ADS)

Shaginyan, V. R.; Msezane, A. Z.; Stephanovich, V. A.; Popov, K. G.; Japaridze, G. S.

2018-04-01

We analyze optical conductivity with the goal to demonstrate experimental manifestation of a new state of matter, the so-called fermion condensate. Fermion condensates are realized in quantum spin liquids, exhibiting typical behavior of heavy-fermion metals. Measurements of the low-frequency optical conductivity collected on the geometrically frustrated insulator herbertsmithite provide important experimental evidence of the nature of its quantum spin liquid composed of spinons. To analyze recent measurements of the herbertsmithite optical conductivity at different temperatures, we employ a model of strongly correlated quantum spin liquid located near the fermion condensation phase transition. Our theoretical analysis of the optical conductivity allows us to expose the physical mechanism of its temperature dependence. We also predict a dependence of the optical conductivity on a magnetic field. We consider an experimental manifestation (optical conductivity) of a new state of matter (so-called fermion condensate) realized in quantum spin liquids, for, in many ways, they exhibit typical behavior of heavy-fermion metals. Measurements of the low-frequency optical conductivity collected on the geometrically frustrated insulator herbertsmithite produce important experimental evidence of the nature of its quantum spin liquid composed of spinons. To analyze recent measurements of the herbertsmithite optical conductivity at different temperatures, we employ a model of a strongly correlated quantum spin liquid located near the fermion condensation phase transition. Our theoretical analysis of the optical conductivity allows us to reveal the physical mechanism of its temperature dependence. We also predict a dependence of the optical conductivity on a magnetic field.

Optical beams with embedded vortices: building blocks for atom optics and quantum information

NASA Astrophysics Data System (ADS)

Chattrapiban, N.; Arakelyan, I.; Mitra, S.; Hill, W. T., III

2006-05-01

Laser beams with embedded vortices, Bessel or Laguerre-Gaussian modes, provide a unique opportunity for creating elements for atom optics, entangling photons and, potentially, mediating novel quantum interconnects between photons and matter. High-order Bessel modes, for example, contain intensity voids and propagate nearly diffraction-free for tens of meters. These vortices can be exploited to produce dark channels oriented longitudinally (hollow beams) or transversely to the laser propagation direction. Such channels are ideal for generating networks or circuits to guide and manipulate cold neutral atoms, an essential requirement for realizing future applications associated with atom interferometry, atom lithography and even some neutral atom-based quantum computing architectures. Recently, we divided a thermal cloud of neutral atoms moving within a blue-detuned beam into two clouds with two different momenta by crossing two hollow beams. In this presentation, we will describe these results and discuss the prospects for extending the process to coherent ensembles of matter.

New insight into the spin-conserving excitation of the negatively charged nitrogen-vacancy center in diamond

PubMed Central

Deng, Bei; Zhang, R. Q.; Shi, X. Q.

2014-01-01

The negatively charged nitrogen-vacancy (N-V−) color center in diamond is an important solid-state single photon source for applications to quantum communication and distributed quantum computation. Its full usefulness relies on sufficient radiative emission of the optical photons which requires realizable control to enhance emission into the zero-phonon line (ZPL) but until now is still a challenge. Detailed understanding of the associated excitation process would be of essential importance for such objective. Here we report a theoretical work that probes the spin-conserving optical excitation of the N-V− center. Using density-functional-theory (DFT) calculations, we find that the ZPL and the phonon-side band (PSB) depend sensitively on the axial strain of the system. Besides, we find a relatively small PSB appearing at about 100 GPa in the emission spectrum at low temperatures, which provides a means to enhance the coherent emission of the N-V− center in quantum optical networks. PMID:24888367

1.55 µm InAs/GaAs Quantum Dots and High Repetition Rate Quantum Dot SESAM Mode-locked Laser

NASA Astrophysics Data System (ADS)

Zhang, Z. Y.; Oehler, A. E. H.; Resan, B.; Kurmulis, S.; Zhou, K. J.; Wang, Q.; Mangold, M.; Süedmeyer, T.; Keller, U.; Weingarten, K. J.; Hogg, R. A.

2012-06-01

High pulse repetition rate (>=10 GHz) diode-pumped solid-state lasers, modelocked using semiconductor saturable absorber mirrors (SESAMs) are emerging as an enabling technology for high data rate coherent communication systems owing to their low noise and pulse-to-pulse optical phase-coherence. Quantum dot (QD) based SESAMs offer potential advantages to such laser systems in terms of reduced saturation fluence, broader bandwidth, and wavelength flexibility. Here, we describe the development of an epitaxial process for the realization of high optical quality 1.55 µm In(Ga)As QDs on GaAs substrates, their incorporation into a SESAM, and the realization of the first 10 GHz repetition rate QD-SESAM modelocked laser at 1.55 µm, exhibiting ~2 ps pulse width from an Er-doped glass oscillator (ERGO). With a high areal dot density and strong light emission, this QD structure is a very promising candidate for many other applications, such as laser diodes, optical amplifiers, non-linear and photonic crystal based devices.

Monolithic integration of InGaAs/InP multiple quantum wells on SOI substrates for photonic devices

NASA Astrophysics Data System (ADS)

Li, Zhibo; Wang, Mengqi; Fang, Xin; Li, Yajie; Zhou, Xuliang; Yu, Hongyan; Wang, Pengfei; Wang, Wei; Pan, Jiaoqing

2018-02-01

A direct epitaxy of III-V nanowires with InGaAs/InP multiple quantum wells on v-shaped trenches patterned silicon on insulator (SOI) substrates was realized by combining the standard semiconductor fabrication process with the aspect ratio trapping growth technique. Silicon thickness as well as the width and gap of each nanowire were carefully designed to accommodate essential optical properties and appropriate growth conditions. The III-V element ingredient, crystalline quality, and surface topography of the grown nanowires were characterized by X-ray diffraction spectroscopy, photoluminescence, and scanning electron microscope. Geometrical details and chemical information of multiple quantum wells were revealed by transmission electron microscopy and energy dispersive spectroscopy. Numerical simulations confirmed that the optical guided mode supported by one single nanowire was able to propagate 50 μm with ˜30% optical loss. This proposed integration scheme opens up an alternative pathway for future photonic integrations of III-V devices on the SOI platform at nanoscale.

Photon wave function formalism for analysis of Mach–Zehnder interferometer and sum-frequency generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ritboon, Atirach, E-mail: atirach.3.14@gmail.com; Department of Physics, Faculty of Science, Prince of Songkla University, Hat Yai 90112; Daengngam, Chalongrat, E-mail: chalongrat.d@psu.ac.th

2016-08-15

Biakynicki-Birula introduced a photon wave function similar to the matter wave function that satisfies the Schrödinger equation. Its second quantization form can be applied to investigate nonlinear optics at nearly full quantum level. In this paper, we applied the photon wave function formalism to analyze both linear optical processes in the well-known Mach–Zehnder interferometer and nonlinear optical processes for sum-frequency generation in dispersive and lossless medium. Results by photon wave function formalism agree with the well-established Maxwell treatments and existing experimental verifications.

Multi-million atom electronic structure calculations for quantum dots

NASA Astrophysics Data System (ADS)

Usman, Muhammad

Quantum dots grown by self-assembly process are typically constructed by 50,000 to 5,000,000 structural atoms which confine a small, countable number of extra electrons or holes in a space that is comparable in size to the electron wavelength. Under such conditions quantum dots can be interpreted as artificial atoms with the potential to be custom tailored to new functionality. In the past decade or so, these nanostructures have attracted significant experimental and theoretical attention in the field of nanoscience. The new and tunable optical and electrical properties of these artificial atoms have been proposed in a variety of different fields, for example in communication and computing systems, medical and quantum computing applications. Predictive and quantitative modeling and simulation of these structures can help to narrow down the vast design space to a range that is experimentally affordable and move this part of nanoscience to nano-Technology. Modeling of such quantum dots pose a formidable challenge to theoretical physicists because: (1) Strain originating from the lattice mismatch of the materials penetrates deep inside the buffer surrounding the quantum dots and require large scale (multi-million atom) simulations to correctly capture its effect on the electronic structure, (2) The interface roughness, the alloy randomness, and the atomistic granularity require the calculation of electronic structure at the atomistic scale. Most of the current or past theoretical calculations are based on continuum approach such as effective mass approximation or k.p modeling capturing either no or one of the above mentioned effects, thus missing some of the essential physics. The Objectives of this thesis are: (1) to model and simulate the experimental quantum dot topologies at the atomistic scale; (2) to theoretically explore the essential physics i.e. long range strain, linear and quadratic piezoelectricity, interband optical transition strengths, quantum confined stark shift, coherent coupling of electronic states in a quantum dot molecule etc.; (3) to assess the potential use of the quantum dots in real device implementation and to provide physical insight to the experimentalists. Full three dimensional strain and electronic structure simulations of quantum dot structures containing multi-million atoms are done using NEMO 3-D. Both single and vertically stacked quantum dot structures are analyzed in detail. The results show that the strain and the piezoelectricity significantly impact the electronic structure of these devices. This work shows that the InAs quantum dots when placed in the InGaAs quantum well red shifts the emission wavelength. Such InAs/GaAs-based optical devices can be used for optical-fiber based communication systems at longer wavelengths (1.3um -- 1.5um). Our atomistic simulations of InAs/InGaAs/GaAs quantum dots quantitatively match with the experiment and give the critical insight of the physics involved in these structures. A single quantum dot molecule is studied for coherent quantum coupling of electronic states under the influence of static electric field applied in the growth direction. Such nanostructures can be used in the implementation of quantum information technologies. A close quantitative match with the experimental optical measurements allowed us to get a physical insight into the complex physics of quantum tunnel couplings of electronic states as the device operation switches between atomic and molecular regimes. Another important aspect is to design the quantum dots for a desired isotropic polarization of the optical emissions. Both single and coupled quantum dots are studied for TE/TM ratio engineering. The atomistic study provides a detailed physical analysis of these computationally expensive large nanostructures and serves as a guide for the experimentalists for the design of the polarization independent devices for the optical communication systems.

Squeezed light in an optical parametric oscillator network with coherent feedback quantum control.

PubMed

Crisafulli, Orion; Tezak, Nikolas; Soh, Daniel B S; Armen, Michael A; Mabuchi, Hideo

2013-07-29

We present squeezing and anti-squeezing spectra of the output from a degenerate optical parametric oscillator (OPO) network arranged in different coherent quantum feedback configurations. One OPO serves as a quantum plant, the other as a quantum controller. The addition of coherent feedback enables shaping of the output squeezing spectrum of the plant, and is found to be capable of pushing the frequency of maximum squeezing away from the optical driving frequency and broadening the spectrum over a wider frequency band. The experimental results are in excellent agreement with the developed theory, and illustrate the use of coherent quantum feedback to engineer the quantum-optical properties of the plant OPO output.

Quantum Dots and Their Multimodal Applications: A Review

PubMed Central

Bera, Debasis; Qian, Lei; Tseng, Teng-Kuan; Holloway, Paul H.

2010-01-01

Semiconducting quantum dots, whose particle sizes are in the nanometer range, have very unusual properties. The quantum dots have band gaps that depend in a complicated fashion upon a number of factors, described in the article. Processing-structure-properties-performance relationships are reviewed for compound semiconducting quantum dots. Various methods for synthesizing these quantum dots are discussed, as well as their resulting properties. Quantum states and confinement of their excitons may shift their optical absorption and emission energies. Such effects are important for tuning their luminescence stimulated by photons (photoluminescence) or electric field (electroluminescence). In this article, decoupling of quantum effects on excitation and emission are described, along with the use of quantum dots as sensitizers in phosphors. In addition, we reviewed the multimodal applications of quantum dots, including in electroluminescence device, solar cell and biological imaging.

A quantum optical firewall based on simple quantum devices

NASA Astrophysics Data System (ADS)

Amellal, H.; Meslouhi, A.; Hassouni, Y.; El Baz, M.

2015-07-01

In order to enhance the transmission security in quantum communications via coherent states, we propose a quantum optical firewall device to protect a quantum cryptosystem against eavesdropping through optical attack strategies. Similar to the classical model of the firewall, the proposed device gives legitimate users the possibility of filtering, controlling (input/output states) and making a decision (access or deny) concerning the traveling states. To prove the security and efficiency of the suggested optical firewall, we analyze its performances against the family of intercept and resend attacks, especially against one of the most prominent attack schemes known as "Faked State Attack."

Quantum optical tests of complementarity: Quantum eraser and the decoherence time of a local measurement process

NASA Astrophysics Data System (ADS)

Abranyos, Yonatan

1999-10-01

Quantum optical tests of the fundamental principles of quantum mechanics, in particular, complementarity, entanglement and non-locality, are the central themes of this dissertation. A which-path experiment is implemented based on a recent experiment by Eichmann et al. [1] involving two four-level atoms. In the version considered here a continuous Broad Band Excitation field drives the two trapped atoms and, depending on the type of scattering, information about which atom scattered the light is stored in the internal degrees of the atoms. Entanglement of the atoms-photon system is intimately connected to the availability of ``which way'' information. The quantum eraser disentangles the atoms-photon system and consequently ``which way'' information is lost leading to interference. Two different experimental schemes based on the Eichmann et al. experiment are proposed for the implementation of the quantum eraser. The quantum eraser schemes erase the ``which way'' information and interference is observed in the second order correlation function. With a slight modification of the experiment, a scheme that allows to verify recently derived inequalities by Englert [2] in connection with distinguishability and visibility in a two-way interferometer is proposed. These inequalities, in some sense, can be regarded as quantifying the notion of wave-particle duality. The visibility of interference depends on the detected polarization direction of the scattered light, and a reading out of the internal atomic states of one of the two atoms provides for partial ``which way'' information or distinguishability of the two different paths. Finally, the quantum eraser is used to measure the decoherence time of a local measurement process. The experiment proposed is similar to the quantum eraser setup and contains the complete measurement process of system-meter-environment interaction. The decoherence time is quantitatively expressed in the amount of reduction of the visibility in the second order correlation function. In addition, it explores how we can cast the question of quantum coherence of mesoscopic or macroscopic systems with a quantum eraser or in general interference experiments.

Production, Manipulation, and Applications of Ultracold Polar Molecules

DTIC Science & Technology

2015-04-30

molecules, cooling, trapping, photoassociation, feshbach resonances, quantum simulation , ultracold collisions, ultracold chemistry, optical lattices...been a multitude of less predictable outcomes: special quantum information processing schemes, uses of entanglement such a spin-squeezing for better...field seeing states to high-field-seeking states (and back) at key points in the magnetic field. The molecules spontaneously emit photons as they are

Magneto optical properties of self-assembled InAs quantum dots for quantum information processing

NASA Astrophysics Data System (ADS)

Tang, Jing; Xu, Xiu-Lai

2018-02-01

Not Available Project supported by the National Basic Research Program of China (Grant No. 2014CB921003), the National Natural Science Foundation of China (Grant Nos. 11721404, 51761145104, and 61675228), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant Nos. XDB07030200 and XDPB0803), and the CAS Interdisciplinary Innovation Team.

Parallel Photonic Quantum Computation Assisted by Quantum Dots in One-Side Optical Microcavities

PubMed Central

Luo, Ming-Xing; Wang, Xiaojun

2014-01-01

Universal quantum logic gates are important elements for a quantum computer. In contrast to previous constructions on one degree of freedom (DOF) of quantum systems, we investigate the possibility of parallel quantum computations dependent on two DOFs of photon systems. We construct deterministic hyper-controlled-not (hyper-CNOT) gates operating on the spatial-mode and the polarization DOFs of two-photon or one-photon systems by exploring the giant optical circular birefringence induced by quantum-dot spins in one-sided optical microcavities. These hyper-CNOT gates show that the quantum states of two DOFs can be viewed as independent qubits without requiring auxiliary DOFs in theory. This result can reduce the quantum resources by half for quantum applications with large qubit systems, such as the quantum Shor algorithm. PMID:25030424

Parallel photonic quantum computation assisted by quantum dots in one-side optical microcavities.

PubMed

Luo, Ming-Xing; Wang, Xiaojun

2014-07-17

Universal quantum logic gates are important elements for a quantum computer. In contrast to previous constructions on one degree of freedom (DOF) of quantum systems, we investigate the possibility of parallel quantum computations dependent on two DOFs of photon systems. We construct deterministic hyper-controlled-not (hyper-CNOT) gates operating on the spatial-mode and the polarization DOFs of two-photon or one-photon systems by exploring the giant optical circular birefringence induced by quantum-dot spins in one-sided optical microcavities. These hyper-CNOT gates show that the quantum states of two DOFs can be viewed as independent qubits without requiring auxiliary DOFs in theory. This result can reduce the quantum resources by half for quantum applications with large qubit systems, such as the quantum Shor algorithm.

Dissipative production of a maximally entangled steady state of two quantum bits.

PubMed

Lin, Y; Gaebler, J P; Reiter, F; Tan, T R; Bowler, R; Sørensen, A S; Leibfried, D; Wineland, D J

2013-12-19

Entangled states are a key resource in fundamental quantum physics, quantum cryptography and quantum computation. Introduction of controlled unitary processes--quantum gates--to a quantum system has so far been the most widely used method to create entanglement deterministically. These processes require high-fidelity state preparation and minimization of the decoherence that inevitably arises from coupling between the system and the environment, and imperfect control of the system parameters. Here we combine unitary processes with engineered dissipation to deterministically produce and stabilize an approximate Bell state of two trapped-ion quantum bits (qubits), independent of their initial states. Compared with previous studies that involved dissipative entanglement of atomic ensembles or the application of sequences of multiple time-dependent gates to trapped ions, we implement our combined process using trapped-ion qubits in a continuous time-independent fashion (analogous to optical pumping of atomic states). By continuously driving the system towards the steady state, entanglement is stabilized even in the presence of experimental noise and decoherence. Our demonstration of an entangled steady state of two qubits represents a step towards dissipative state engineering, dissipative quantum computation and dissipative phase transitions. Following this approach, engineered coupling to the environment may be applied to a broad range of experimental systems to achieve desired quantum dynamics or steady states. Indeed, concurrently with this work, an entangled steady state of two superconducting qubits was demonstrated using dissipation.

Fundamental rate-loss tradeoff for optical quantum key distribution.

PubMed

Takeoka, Masahiro; Guha, Saikat; Wilde, Mark M

2014-10-24

Since 1984, various optical quantum key distribution (QKD) protocols have been proposed and examined. In all of them, the rate of secret key generation decays exponentially with distance. A natural and fundamental question is then whether there are yet-to-be discovered optical QKD protocols (without quantum repeaters) that could circumvent this rate-distance tradeoff. This paper provides a major step towards answering this question. Here we show that the secret key agreement capacity of a lossy and noisy optical channel assisted by unlimited two-way public classical communication is limited by an upper bound that is solely a function of the channel loss, regardless of how much optical power the protocol may use. Our result has major implications for understanding the secret key agreement capacity of optical channels-a long-standing open problem in optical quantum information theory-and strongly suggests a real need for quantum repeaters to perform QKD at high rates over long distances.

The influence of the quantum dot/polymethylmethacrylate composite preparation method on the stability of its optical properties under laser radiation

NASA Astrophysics Data System (ADS)

Zvaigzne, M. A.; Martynov, I. L.; Krivenkov, V. A.; Samokhvalov, P. S.; Nabiev, I. R.

2017-01-01

Photoluminescent semiconductor nanocrystals, quantum dots (QDs), are nowadays one of the most promising materials for developing a new generation of fluorescent labels, new types of light-emitting devices and displays, flexible electronic components, and solar panels. In many areas the use of QDs is associated with an intense optical excitation, which, in the case of a prolonged exposure, often leads to changes in their optical characteristics. In the present work we examined how the method of preparation of quantum dot/polymethylmethacrylate (QD/PMMA) composite influenced the stability of the optical properties of QD inside the polymer matrix under irradiation by different laser harmonics in the UV (355 nm) and visible (532 nm) spectral regions. The composites were synthesized by spin-coating and radical polymerization methods. Experiments with the samples obtained by spin-coating showed that the properties of the QD/PMMA films remain almost constant at values of the radiation dose below 10 fJ per particle. Irradiating the composites prepared by the radical polymerization method, we observed a monotonic increase in the luminescence quantum yield (QY) accompanied by an increase in the luminescence decay time regardless of the wavelength of the incident radiation. We assume that the observed difference in the optical properties of the samples under exposure to laser radiation is associated with the processes occurring during radical polymerization, in particular, with charge transfer from the radical particles inside QDs. The results of this study are important for understanding photophysical properties of composites on the basis of QDs, as well as for selection of the type of polymer and the composite synthesis method with quantum dots that would allow one to avoid the degradation of their luminescence.

Arthur L. Schawlow Prize in Laser Science Talk: Trapped Ion Quantum Networks with Light

NASA Astrophysics Data System (ADS)

Monroe, Christopher

2015-05-01

Laser-cooled atomic ions are standards for quantum information science, acting as qubit memories with unsurpassed levels of quantum coherence while also allowing near-perfect measurement. When qubit state-dependent optical dipole forces are applied to a collection of trapped ions, their Coulomb interaction is modulated in a way that allows the entanglement of the qubits through quantum gates that can form the basis of a quantum computer. Similar optical forces allow the simulation of quantum many-body physics, where recent experiments are approaching a level of complexity that cannot be modelled with conventional computers. Scaling to much larger numbers of qubits can be accomplished by coupling trapped ion qubits through optical photons, where entanglement over remote distances can be used for quantum communication and large-scale distributed quantum computers. Laser sources and quantum optical techniques are the workhorse for such quantum networks, and will continue to lead the way as future quantum hardware is developed. This work is supported by the ARO with funding from the IARPA MQCO program, the DARPA Quiness Program, the ARO MURI on Hybrid Quantum Circuits, the AFOSR MURIs on Quantum Transduction and Quantum Verification, and the NSF Physics Frontier Center at JQI.

Optical emission of GaN/AlN quantum-wires - the role of charge transfer from a nanowire template.

PubMed

Müßener, Jan; Greif, Ludwig A Th; Kalinowski, Stefan; Callsen, Gordon; Hille, Pascal; Schörmann, Jörg; Wagner, Markus R; Schliwa, Andrei; Martí-Sánchez, Sara; Arbiol, Jordi; Hoffmann, Axel; Eickhoff, Martin

2018-03-28

We show that one-dimensional (1d) GaN quantum-wires (QWRs) exhibit intense and spectrally sharp emission lines. These QWRs are realized in an entirely self-assembled growth process by molecular beam epitaxy (MBE) on the side facets of GaN/AlN nanowire (NW) heterostructures. Time-integrated and time-resolved photoluminescence (PL) data in combination with numerical calculations allow the identification and assignment of the manifold emission features to three different spatial recombination centers within the NWs. The recombination processes in the QWRs are driven by efficient charge carrier transfer effects between the different optically active regions, providing high intense QWR luminescence despite their small volume. This is deduced by a fast rise time of the QWR PL, which is similar to the fast decay-time of adjacent carrier reservoirs. Such processes, feeding the ultra-narrow QWRs with carriers from the relatively large NWs, can be the key feature towards the realization of future QWR-based devices. While processing of single quantum structures with diameters in the nm range presents a serious obstacle with respect to their integration into electronic or photonic devices, the QWRs presented here can be analyzed and processed using existing techniques developed for single NWs.

CALL FOR PAPERS: Quantum control

NASA Astrophysics Data System (ADS)

Mancini, Stefano; Wiseman, Howard M.; Man'ko, Vladimir I.

2004-10-01

Over the last few decades, the achievements of highly precise technologies for manipulating systems at quantum scales have paved the way for the development of quantum control. Moreover, the proliferation of results in quantum information suggest that control theory might profitably be re-examined from this perspective. Journal of Optics B: Quantum and Semiclassical Optics will publish a topical issue devoted to quantum control. The Guest Editors invite contributions from researchers working in any area related to quantum control. Topics to be covered include: • Quantum Hamiltonian dynamics and programming control • Quantum decoherence control • Open loop control • Closed loop (feedback) control • Quantum measurement theory • Quantum noise and filtering • Estimation and decision theory • Quantum error correction • Group representation in quantum control • Coherent control in quantum optics and lasers • Coherent control in cavity QED and atom optics • Coherent control in molecular dynamics The topical issue is scheduled for publication in November 2005 and the DEADLINE for submission of contributions is 28 February 2005. All contributions will be peer-reviewed in accordance with the normal refereeing procedures and standards of Journal of Optics B: Quantum and Semiclassical Optics. Submissions should preferably be in either standard LaTeX form or Microsoft Word. Advice on publishing your work in the journal may be found at www.iop.org/journals/authors/jopb. Enquiries regarding this topical issue may be addressed to the Publisher, Dr Claire Bedrock (claire.bedrock@iop.org). There are no page charges for publication. The corresponding author of each paper published will receive a complimentary copy of the topical issue. Contributions to the topical issue should preferably be submitted electronically at www.iop.org/journals/authors/jopb or by e-mail to jopb@iop.org. Authors unable to submit online or by e-mail may send hard copy contributions (enclosing the electronic code) to: Journal of Optics B: Quantum and Semiclassical Optics, Institute of Physics Publishing, Dirac House, Temple Back, Bristol BS1 6BE, UK. All contributions should be accompanied by a readme file or covering letter, quoting `JOPB Topical Issue - Quantum control', giving the postal and e-mail addresses for correspondence. Any subsequent change of address should be notified to the publishing office. We look forward to receiving your contribution to this topical issue.

Experimental methods of molecular matter-wave optics.

PubMed

Juffmann, Thomas; Ulbricht, Hendrik; Arndt, Markus

2013-08-01

We describe the state of the art in preparing, manipulating and detecting coherent molecular matter. We focus on experimental methods for handling the quantum motion of compound systems from diatomic molecules to clusters or biomolecules.Molecular quantum optics offers many challenges and innovative prospects: already the combination of two atoms into one molecule takes several well-established methods from atomic physics, such as for instance laser cooling, to their limits. The enormous internal complexity that arises when hundreds or thousands of atoms are bound in a single organic molecule, cluster or nanocrystal provides a richness that can only be tackled by combining methods from atomic physics, chemistry, cluster physics, nanotechnology and the life sciences.We review various molecular beam sources and their suitability for matter-wave experiments. We discuss numerous molecular detection schemes and give an overview over diffraction and interference experiments that have already been performed with molecules or clusters.Applications of de Broglie studies with composite systems range from fundamental tests of physics up to quantum-enhanced metrology in physical chemistry, biophysics and the surface sciences.Nanoparticle quantum optics is a growing field, which will intrigue researchers still for many years to come. This review can, therefore, only be a snapshot of a very dynamical process.

Quantum information processing by weaving quantum Talbot carpets

NASA Astrophysics Data System (ADS)

Farías, Osvaldo Jiménez; de Melo, Fernando; Milman, Pérola; Walborn, Stephen P.

2015-06-01

Single-photon interference due to passage through a periodic grating is considered in a novel proposal for processing D -dimensional quantum systems (quDits) encoded in the spatial degrees of freedom of light. We show that free-space propagation naturally implements basic single-quDit gates by means of the Talbot effect: an intricate time-space carpet of light in the near-field diffraction regime. By adding a diagonal phase gate, we show that a complete set of single-quDit gates can be implemented. We then introduce a spatially dependent beam splitter that allows for projective measurements in the computational basis and can be used for the implementation of controlled operations between two quDits. Universal quantum information processing can then be implemented with linear optics and ancilla photons via postselection and feed-forward following the original proposal of Knill-Laflamme and Milburn. Although we consider photons, our scheme should be directly applicable to a number of other physical systems. Interpretation of the Talbot effect as a quantum logic operation provides a beautiful and interesting way to visualize quantum computation through wave propagation and interference.

Tunable room-temperature spin-selective optical Stark effect in solution-processed layered halide perovskites.

PubMed

Giovanni, David; Chong, Wee Kiang; Dewi, Herlina Arianita; Thirumal, Krishnamoorthy; Neogi, Ishita; Ramesh, Ramamoorthy; Mhaisalkar, Subodh; Mathews, Nripan; Sum, Tze Chien

2016-06-01

Ultrafast spin manipulation for opto-spin logic applications requires material systems that have strong spin-selective light-matter interaction. Conventional inorganic semiconductor nanostructures [for example, epitaxial II to VI quantum dots and III to V multiple quantum wells (MQWs)] are considered forerunners but encounter challenges such as lattice matching and cryogenic cooling requirements. Two-dimensional halide perovskite semiconductors, combining intrinsic tunable MQW structures and large oscillator strengths with facile solution processability, can offer breakthroughs in this area. We demonstrate novel room-temperature, strong ultrafast spin-selective optical Stark effect in solution-processed (C6H4FC2H4NH3)2PbI4 perovskite thin films. Exciton spin states are selectively tuned by ~6.3 meV using circularly polarized optical pulses without any external photonic cavity (that is, corresponding to a Rabi energy of ~55 meV and equivalent to applying a 70 T magnetic field), which is much larger than any conventional system. The facile halide and organic replacement in these perovskites affords control of the dielectric confinement and thus presents a straightforward strategy for tuning light-matter coupling strength.

Interaction-induced decay of a heteronuclear two-atom system

PubMed Central

Xu, Peng; Yang, Jiaheng; Liu, Min; He, Xiaodong; Zeng, Yong; Wang, Kunpeng; Wang, Jin; Papoular, D. J.; Shlyapnikov, G. V.; Zhan, Mingsheng

2015-01-01

Two-atom systems in small traps are of fundamental interest for understanding the role of interactions in degenerate cold gases and for the creation of quantum gates in quantum information processing with single-atom traps. One of the key quantities is the inelastic relaxation (decay) time when one of the atoms or both are in a higher hyperfine state. Here we measure this quantity in a heteronuclear system of 87Rb and 85Rb in a micro optical trap and demonstrate experimentally and theoretically the presence of both fast and slow relaxation processes, depending on the choice of the initial hyperfine states. This experimental method allows us to single out a particular relaxation process thus provides an extremely clean platform for collisional physics studies. Our results have also implications for engineering of quantum states via controlled collisions and creation of two-qubit quantum gates. PMID:26199051

A multistate pH-triggered nonlinear optical switch.

PubMed

Castet, Frédéric; Champagne, Benoît; Pina, Fernando; Rodriguez, Vincent

2014-08-04

By using hyper-Rayleigh scattering experiments and quantum-chemical calculations, we demonstrate that nonlinear optics can be used to probe unequivocally, within a non-destructive process, the multiple electronic states that are activated upon pH- and light-triggered transformations of the 4'-hydroxyflavylium ion. These results open new perspectives in the design of molecular-scale high-density optical memory. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Robust bidirectional links for photonic quantum networks

PubMed Central

Xu, Jin-Shi; Yung, Man-Hong; Xu, Xiao-Ye; Tang, Jian-Shun; Li, Chuan-Feng; Guo, Guang-Can

2016-01-01

Optical fibers are widely used as one of the main tools for transmitting not only classical but also quantum information. We propose and report an experimental realization of a promising method for creating robust bidirectional quantum communication links through paired optical polarization-maintaining fibers. Many limitations of existing protocols can be avoided with the proposed method. In particular, the path and polarization degrees of freedom are combined to deterministically create a photonic decoherence-free subspace without the need for any ancillary photon. This method is input state–independent, robust against dephasing noise, postselection-free, and applicable bidirectionally. To rigorously quantify the amount of quantum information transferred, the optical fibers are analyzed with the tools developed in quantum communication theory. These results not only suggest a practical means for protecting quantum information sent through optical quantum networks but also potentially provide a new physical platform for enriching the structure of the quantum communication theory. PMID:26824069

High Photoluminescence Quantum Yield in Band Gap Tunable Bromide Containing Mixed Halide Perovskites

DOE PAGES

Sutter-Fella, Carolin M.; Li, Yanbo; Amani, Matin; ...

2015-12-21

Hybrid organic-inorganic halide perovskite based semiconductor materials are attractive for use in a wide range of optoelectronic devices because they combine the advantages of suitable optoelectronic attributes and simultaneously low-cost solution processability. Here, we present a two-step low-pressure vapor-assisted solution process to grow high quality homogeneous CH 3NH 3PbI 3-xBr x perovskite films over the full band gap range of 1.6-2.3 eV. Photoluminescence light-in versus light-out characterization techniques are used to provide new insights into the optoelectronic properties of Br-containing hybrid organic-inorganic perovskites as a function of optical carrier injection by employing pump-powers over a 6 orders of magnitude dynamicmore » range. The internal luminescence quantum yield of wide band gap perovskites reaches impressive values up to 30%. This high quantum yield translates into substantial quasi-Fermi level splitting and high "luminescence or optically implied" open-circuit voltage. Most importantly, both attributes, high internal quantum yield and high optically implied open-circuit voltage, are demonstrated over the entire band gap range (1.6 eV ≤ E g ≤ 2.3 eV). These results establish the versatility of Br-containing perovskite semiconductors for a variety of applications and especially for the use as high-quality top cell in tandem photovoltaic devices in combination with industry dominant Si bottom cells. (Figure Presented).« less

Transient Evolutional Dynamics of Quantum-Dot Molecular Phase Coherence for Sensitive Optical Switching

NASA Astrophysics Data System (ADS)

Shen, Jian Qi; Gu, Jing

2018-04-01

Atomic phase coherence (quantum interference) in a multilevel atomic gas exhibits a number of interesting phenomena. Such an atomic quantum coherence effect can be generalized to a quantum-dot molecular dielectric. Two quantum dots form a quantum-dot molecule, which can be described by a three-level Λ-configuration model { |0> ,|1> ,|2> } , i.e., the ground state of the molecule is the lower level |0> and the highly degenerate electronic states in the two quantum dots are the two upper levels |1> ,|2> . The electromagnetic characteristics due to the |0>-|1> transition can be controllably manipulated by a tunable gate voltage (control field) that drives the |2>-|1> transition. When the gate voltage is switched on, the quantum-dot molecular state can evolve from one steady state (i.e., |0>-|1> two-level dressed state) to another steady state (i.e., three-level coherent-population-trapping state). In this process, the electromagnetic characteristics of a quantum-dot molecular dielectric, which is modified by the gate voltage, will also evolve. In this study, the transient evolutional behavior of the susceptibility of a quantum-dot molecular thin film and its reflection spectrum are treated by using the density matrix formulation of the multilevel systems. The present field-tunable and frequency-sensitive electromagnetic characteristics of a quantum-dot molecular thin film, which are sensitive to the applied gate voltage, can be utilized to design optical switching devices.

PREFACE: International Conference on Quantum Optics and Quantum Information (icQoQi) 2013

NASA Astrophysics Data System (ADS)

2014-11-01

Quantum Information can be understood as being naturally derived from a new understanding of information theory when quantum systems become information carriers and quantum effects become non negligible. Experiments and the realization of various interesting phenomena in quantum information within the established field of quantum optics have been reported, which has provided a very convenient framework for the former. Together, quantum optics and quantum information are among the most exciting areas of interdisciplinary research in modern day science which cover a broad spectrum of topics, from the foundations of quantum mechanics and quantum information science to the introduction of new types of quantum technologies and metrology. The International Conference on Quantum Optics and Quantum Information (icQoQi) 2013 was organized by the Faculty of Science, International Islamic University Malaysia with the objective of bringing together leading academic scientists, researchers and scholars in the domain of interest from around the world to share their experiences and research results about all aspects of quantum optics and quantum information. While the event was organized on a somewhat modest scale, it was in fact a rather fruitful meeting for established researchers and students as well, especially for the local scene where the field is relatively new. We would therefore, like to thank the organizing committee, our advisors and all parties for having made this event successful and last but not least would extend our sincerest gratitude to IOP for publishing these selected papers from icQoQi2013 in Journal of Physics: Conference Series.

Quantum theory of phonon-mediated decoherence and relaxation of two-level systems in a structured electromagnetic reservoir

NASA Astrophysics Data System (ADS)

Roy, Chiranjeeb

In this thesis we study the role of nonradiative degrees of freedom on quantum optical properties of mesoscopic quantum dots placed in the structured electromagnetic reservoir of a photonic crystal. We derive a quantum theory of the role of acoustic and optical phonons in modifying the optical absorption lineshape, polarization dynamics, and population dynamics of a two-level atom (quantum dot) in the "colored" electromagnetic vacuum of a photonic band gap (PBG) material. This is based on a microscopic Hamiltonian describing both radiative and vibrational processes quantum mechanically. Phonon sidebands in an ordinary electromagnetic reservoir are recaptured in a simple model of optical phonons using a mean-field factorization of the atomic and lattice displacement operators. Our formalism is then used to treat the non-Markovian dynamics of the same system within the structured electromagnetic density of states of a photonic crystal. We elucidate the extent to which phonon-assisted decay limits the lifetime of a single photon-atom bound state and derive the modified spontaneous emission dynamics due to coupling to various phonon baths. We demonstrate that coherent interaction with undamped phonons can lead to enhanced lifetime of a photon-atom bound state in a PBG by (i) dephasing and reducing the transition electric dipole moment of the atom and (ii) reducing the quantum mechanical overlap of the state vectors of the excited and ground state (polaronic shift). This results in reduction of the steady-state atomic polarization but an increase in the fractionalized upper state population in the photon-atom bound state. We demonstrate, on the other hand, that the lifetime of the photon-atom bound state in a PBG is limited by the lifetime of phonons due to lattice anharmonicities (break-up of phonons into lower energy phonons) and purely nonradiative decay. We demonstrate how these additional damping effects limit the extent of the polaronic (Franck-Condon) shift of the atomic excited state. We also derive the modified polarization decay and dephasing rates in the presence of such damping. This leads to a microscopic, quantum theory of the optical absorption lineshapes. Our model and formalism provide a starting point for describing dephasing and relaxation in the presence of external coherent fields and multiple quantum dot interactions in electromagnetic reservoirs with radiative memory effects.

Quantum decoherence of phonons in Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Howl, Richard; Sabín, Carlos; Hackermüller, Lucia; Fuentes, Ivette

2018-01-01

We apply modern techniques from quantum optics and quantum information science to Bose-Einstein condensates (BECs) in order to study, for the first time, the quantum decoherence of phonons of isolated BECs. In the last few years, major advances in the manipulation and control of phonons have highlighted their potential as carriers of quantum information in quantum technologies, particularly in quantum processing and quantum communication. Although most of these studies have focused on trapped ion and crystalline systems, another promising system that has remained relatively unexplored is BECs. The potential benefits in using this system have been emphasized recently with proposals of relativistic quantum devices that exploit quantum states of phonons in BECs to achieve, in principle, superior performance over standard non-relativistic devices. Quantum decoherence is often the limiting factor in the practical realization of quantum technologies, but here we show that quantum decoherence of phonons is not expected to heavily constrain the performance of these proposed relativistic quantum devices.

Call for Papers: Cavity QED

NASA Astrophysics Data System (ADS)

Lange, W.; Gerard, J.-M.

2003-06-01

Cavity QED interactions of light and matter have been investigated in a wide range of systems covering the spectrum from microwaves to optical frequencies, using media as diverse as single atoms and semiconductors. Impressive progress has been achieved technologically as well as conceptually. This topical issue of Journal of Optics B: Quantum and Semiclassical Optics is intended to provide a comprehensive account of the current state of the art of cavity QED by uniting contributions from researchers active across this field. As Guest Editors of this topical issue, we invite manuscripts on current theoretical and experimental work on any aspects of cavity QED. The topics to be covered will include, but are not limited to: bulletCavity QED in optical microcavities bulletSemiconductor cavity QED bulletQuantum dot cavity QED bulletRydberg atoms in microwave cavities bulletPhotonic crystal cavity QED bulletMicrosphere resonators bulletMicrolasers and micromasers bulletMicrodroplets bulletDielectric cavity QED bulletCavity QED-based quantum information processing bulletQuantum state engineering in cavities The DEADLINE for submission of contributions is 31 July 2003 to allow the topical issue to appear in about February 2004. All papers will be peer-reviewed in accordance with the normal refereeing procedures and standards of Journal of Optics B: Quantum and Semiclassical Optics. Advice on publishing your work in the journal may be found at www.iop.org/journals/authors/jopb. Submissions should ideally be in either standard LaTeX form or Microsoft Word. There are no page charges for publication. In addition to the usual 50 free reprints, the corresponding author of each paper published will receive a complimentary copy of the topical issue. Contributions to the topical issue should if possible be submitted electronically at www.iop.org/journals/jopb. or by e-mail to jopb@iop.org. Authors unable to submit online or by e-mail may send hard copy contributions (enclosing the electronic code) to: Dr Claire Bedrock (Publisher), Journal of Optics B: Quantum and Semiclassical Optics, Institute of Physics Publishing, Dirac House, Temple Back, Bristol BS1 6BE, UK. All contributions should be accompanied by a readme file or covering letter, quoting `JOPB topical issue - Cavity QED', giving the postal and e-mail addresses for correspondence. Any subsequent change of address should be notified to the publishing office. We look forward to receiving your contribution to this topical issue.

Quantum Algorithmic Readout in Multi-Ion Clocks.

PubMed

Schulte, M; Lörch, N; Leroux, I D; Schmidt, P O; Hammerer, K

2016-01-08

Optical clocks based on ensembles of trapped ions promise record frequency accuracy with good short-term stability. Most suitable ion species lack closed transitions, so the clock signal must be read out indirectly by transferring the quantum state of the clock ions to cotrapped logic ions of a different species. Existing methods of quantum logic readout require a linear overhead in either time or the number of logic ions. Here we describe a quantum algorithmic readout whose overhead scales logarithmically with the number of clock ions in both of these respects. The scheme allows a quantum nondemolition readout of the number of excited clock ions using a single multispecies gate operation which can also be used in other areas of ion trap technology such as quantum information processing, quantum simulations, metrology, and precision spectroscopy.

InGaAs/InP quantum wires grown on silicon with adjustable emission wavelength at telecom bands

NASA Astrophysics Data System (ADS)

Han, Yu; Li, Qiang; Ng, Kar Wei; Zhu, Si; Lau, Kei May

2018-06-01

We report the growth of vertically stacked InGaAs/InP quantum wires on (001) Si substrates with adjustable room-temperature emission at telecom bands. Based on a self-limiting growth mode in selective area metal–organic chemical vapor deposition, crescent-shaped InGaAs quantum wires with variable dimensions are embedded within InP nano-ridges. With extensive transmission electron microscopy studies, the growth transition and morphology change from quantum wires to ridge quantum wells (QWs) have been revealed. As a result, we are able to decouple the quantum wires from ridge QWs and manipulate their dimensions by scaling the growth time. With minimized lateral dimension and their unique positioning, the InGaAs/InP quantum wires are more immune to dislocations and more efficient in radiative processes, as evidenced by their excellent optical quality at telecom-bands. These promising results thus highlight the potential of combining low-dimensional quantum wire structures with the aspect ratio trapping process for integrating III–V nano-light emitters on mainstream (001) Si substrates.

InGaAs/InP quantum wires grown on silicon with adjustable emission wavelength at telecom bands.

PubMed

Han, Yu; Li, Qiang; Ng, Kar Wei; Zhu, Si; Lau, Kei May

2018-06-01

We report the growth of vertically stacked InGaAs/InP quantum wires on (001) Si substrates with adjustable room-temperature emission at telecom bands. Based on a self-limiting growth mode in selective area metal-organic chemical vapor deposition, crescent-shaped InGaAs quantum wires with variable dimensions are embedded within InP nano-ridges. With extensive transmission electron microscopy studies, the growth transition and morphology change from quantum wires to ridge quantum wells (QWs) have been revealed. As a result, we are able to decouple the quantum wires from ridge QWs and manipulate their dimensions by scaling the growth time. With minimized lateral dimension and their unique positioning, the InGaAs/InP quantum wires are more immune to dislocations and more efficient in radiative processes, as evidenced by their excellent optical quality at telecom-bands. These promising results thus highlight the potential of combining low-dimensional quantum wire structures with the aspect ratio trapping process for integrating III-V nano-light emitters on mainstream (001) Si substrates.

Cryo-mediated exfoliation and fracturing of layered materials into 2D quantum dots

PubMed Central

Wang, Yan; Liu, Yang; Zhang, Jianfang; Wu, Jingjie; Xu, Hui; Wen, Xiewen; Zhang, Xiang; Tiwary, Chandra Sekhar; Yang, Wei; Vajtai, Robert; Zhang, Yong; Chopra, Nitin; Odeh, Ihab Nizar; Wu, Yucheng; Ajayan, Pulickel M.

2017-01-01

Atomically thin quantum dots from layered materials promise new science and applications, but their scalable synthesis and separation have been challenging. We demonstrate a universal approach for the preparation of quantum dots from a series of materials, such as graphite, MoS2, WS2, h-BN, TiS2, NbS2, Bi2Se3, MoTe2, Sb2Te3, etc., using a cryo-mediated liquid-phase exfoliation and fracturing process. The method relies on liquid nitrogen pretreatment of bulk layered materials before exfoliation and breakdown into atomically thin two-dimensional quantum dots of few-nanometer lateral dimensions, exhibiting size-confined optical properties. This process is efficient for a variety of common solvents with a wide range of surface tension parameters and eliminates the use of surfactants, resulting in pristine quantum dots without surfactant covering or chemical modification. PMID:29250597

Locality and universality of quantum memory effects.

PubMed

Liu, B-H; Wißmann, S; Hu, X-M; Zhang, C; Huang, Y-F; Li, C-F; Guo, G-C; Karlsson, A; Piilo, J; Breuer, H-P

2014-09-11

The modeling and analysis of the dynamics of complex systems often requires to employ non-Markovian stochastic processes. While there is a clear and well-established mathematical definition for non-Markovianity in the case of classical systems, the extension to the quantum regime recently caused a vivid debate, leading to many different proposals for the characterization and quantification of memory effects in the dynamics of open quantum systems. Here, we derive a mathematical representation for the non-Markovianity measure based on the exchange of information between the open system and its environment, which reveals the locality and universality of non-Markovianity in the quantum state space and substantially simplifies its numerical and experimental determination. We further illustrate the application of this representation by means of an all-optical experiment which allows the measurement of the degree of memory effects in a photonic quantum process with high accuracy.

Intrication temporelle et communication quantique

NASA Astrophysics Data System (ADS)

Bussieres, Felix

Quantum communication is the art of transferring a quantum state from one place to another and the study of tasks that can be accomplished with it. This thesis is devoted to the development of tools and tasks for quantum communication in a real-world setting. These were implemented using an underground optical fibre link deployed in an urban environment. The technological and theoretical innovations presented here broaden the range of applications of time-bin entanglement through new methods of manipulating time-bin qubits, a novel model for characterizing sources of photon pairs, new ways of testing non-locality and the design and the first implementation of a new loss-tolerant quantum coin-flipping protocol. Manipulating time-bin qubits. A single photon is an excellent vehicle in which a qubit, the fundamental unit of quantum information, can be encoded. In particular, the time-bin encoding of photonic qubits is well suited for optical fibre transmission. Before this thesis, the applications of quantum communication based on the time-bin encoding were limited due to the lack of methods to implement arbitrary operations and measurements. We have removed this restriction by proposing the first methods to realize arbitrary deterministic operations on time-bin qubits as well as single qubit measurements in an arbitrary basis. We applied these propositions to the specific case of optical measurement-based quantum computing and showed how to implement the feedforward operations, which are essential to this model. This therefore opens new possibilities for creating an optical quantum computer, but also for other quantum communication tasks. Characterizing sources of photon pairs. Experimental quantum communication requires the creation of single photons and entangled photons. These two ingredients can be obtained from a source of photon pairs based on non-linear spontaneous processes. Several tasks in quantum communication require a precise knowledge of the properties of the source being used. We developed and implemented a fast and simple method to characterize a source of photon pairs. This method is well suited for a realistic setting where experimental conditions, such as channel transmittance, may fluctuate, and for which the characterization of the source has to be done in real time. Testing the non-locality of time-bin entanglement. Entanglement is a resource needed for the realization of many important tasks in quantum communication. It also allows two physical systems to be correlated in a way that cannot be explained by classical physics; this manifestation of entanglement is called non-locality. We built a source of time-bin entangled photonic qubits and characterized it with the new methods implementing arbitrary single qubit measurements that we developed. This allowed us to reveal the non-local nature of our source of entanglement in ways that were never implemented before. It also opens the door to study previously untested features of non-locality using this source. Theses experiments were performed in a realistic setting where quantum (non-local) correlations were observed even after transmission of one of the entangled qubits over 12.4 km of an underground optical fibre. Flipping quantum coins. Quantum coin-flipping is a quantum cryptographic primitive proposed in 1984, that is when the very first steps of quantum communication were being taken, where two players alternate in sending classical and quantum information in order to generate a shared random bit. The use of quantum information is such that a potential cheater cannot force the outcome to his choice with certainty. Classically, however, one of the players can always deterministically choose the outcome. Unfortunately, the security of all previous quantum coin-flipping protocols is seriously compromised in the presence of losses on the transmission channel, thereby making this task impractical. We found a solution to this problem and obtained the first loss-tolerant quantum coin-flipping protocol whose security is independent of the amount of the losses. We have also experimentally demonstrated our loss-tolerant protocol using our source of time-bin entanglement combined with our arbitrary single qubit measurement methods. This experiment took place in a realistic setting where qubits travelled over an underground optical fibre link. This new task thus joins quantum key distribution as a practical application of quantum communication. Keywords. quantum communication, photonics, time-bin encoding, source of photon pairs, heralded single photon source, entanglement, non-locality, time-bin entanglement, hybrid entanglement, quantum network, quantum cryptography, quantum coin-flipping, measurement-based quantum computation, telecommunication, optical fibre, nonlinear optics.

Optical pumping and negative luminescence polarization in charged GaAs quantum dots

NASA Astrophysics Data System (ADS)

Shabaev, Andrew; Stinaff, Eric A.; Bracker, Allan S.; Gammon, Daniel; Efros, Alexander L.; Korenev, Vladimir L.; Merkulov, Igor

2009-01-01

Optical pumping of electron spins and negative photoluminescence polarization are observed when interface quantum dots in a GaAs quantum well are excited nonresonantly by circularly polarized light. Both observations can be explained by the formation of long-lived dark excitons through hole spin relaxation in the GaAs quantum well prior to exciton capture. In this model, optical pumping of resident electron spins is caused by capture of dark excitons and recombination in charged quantum dots. Negative polarization results from accumulation of dark excitons in the quantum well and is enhanced by optical pumping. The dark exciton model describes the experimental results very well, including intensity and bias dependence of the photoluminescence polarization and the Hanle effect.

Quantum cryptography over underground optical fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hughes, R.J.; Luther, G.G.; Morgan, G.L.

1996-05-01

Quantum cryptography is an emerging technology in which two parties may simultaneously generated shared, secret cryptographic key material using the transmission of quantum states of light whose security is based on the inviolability of the laws of quantum mechanics. An adversary can neither successfully tap the key transmissions, nor evade detection, owing to Heisenberg`s uncertainty principle. In this paper the authors describe the theory of quantum cryptography, and the most recent results from their experimental system with which they are generating key material over 14-km of underground optical fiber. These results show that optical-fiber based quantum cryptography could allow secure,more » real-time key generation over ``open`` multi-km node-to-node optical fiber communications links between secure ``islands.``« less

Quantum optical effective-medium theory and transformation quantum optics for metamaterials

NASA Astrophysics Data System (ADS)

Wubs, Martijn; Amooghorban, Ehsan; Zhang, Jingjing; Mortensen, N. Asger

2016-09-01

While typically designed to manipulate classical light, metamaterials have many potential applications for quantum optics as well. We argue why a quantum optical effective-medium theory is needed. We present such a theory for layered metamaterials that is valid for light propagation in all spatial directions, thereby generalizing earlier work for one-dimensional propagation. In contrast to classical effective-medium theory there is an additional effective parameter that describes quantum noise. Our results for metamaterials are based on a rather general Lagrangian theory for the quantum electrodynamics of media with both loss and gain. In the second part of this paper, we present a new application of transformation optics whereby local spontaneous-emission rates of quantum emitters can be designed. This follows from an analysis how electromagnetic Green functions trans- form under coordinate transformations. Spontaneous-emission rates can be either enhanced or suppressed using invisibility cloaks or gradient index lenses. Furthermore, the anisotropic material profile of the cloak enables the directional control of spontaneous emission.

SeaQuaKE: Sea-Optimized Quantum Key Exchange

DTIC Science & Technology

2014-08-01

which is led by Applied Communications Sciences under the ONR Free Space Optical Quantum Key Distribution Special Notice (13-SN-0004 under ONRBAA13...aerosol model scenarios. 15. SUBJECT TERMS Quantum communications, free - space optical communications 16. SECURITY CLASSIFICATION OF: 17...SeaQuaKE) project, which is led by Applied Communications Sciences under the ONR Free Space Optical Quantum Key Distribution Special Notice (13-SN

Quantum Error Correction with a Globally-Coupled Array of Neutral Atom Qubits

DTIC Science & Technology

2013-02-01

magneto - optical trap ) located at the center of the science cell. Fluorescence...Bottle beam trap GBA Gaussian beam array EMCCD electron multiplying charge coupled device microsec. microsecond MOT Magneto - optical trap QEC quantum error correction qubit quantum bit ...developed and implemented an array of neutral atom qubits in optical traps for studies of quantum error correction. At the end of the three year

Quantum entangled dark solitons formed by ultracold atoms in optical lattices.

PubMed

Mishmash, R V; Carr, L D

2009-10-02

Inspired by experiments on Bose-Einstein condensates in optical lattices, we study the quantum evolution of dark soliton initial conditions in the context of the Bose-Hubbard Hamiltonian. An extensive set of quantum measures is utilized in our analysis, including von Neumann and generalized quantum entropies, quantum depletion, and the pair correlation function. We find that quantum effects cause the soliton to fill in. Moreover, soliton-soliton collisions become inelastic, in strong contrast to the predictions of mean-field theory. These features show that the lifetime and collision properties of dark solitons in optical lattices provide clear signals of quantum effects.

Microscopic theory of multiple-phonon-mediated dephasing and relaxation of quantum dots near a photonic band gap

NASA Astrophysics Data System (ADS)

Roy, Chiranjeeb; John, Sajeev

2010-02-01

We derive a quantum theory of the role of acoustic and optical phonons in modifying the optical absorption line shape, polarization dynamics, and population dynamics of a two-level atom (quantum dot) in the “colored” electromagnetic vacuum of a photonic band-gap (PBG) material. This is based on a microscopic Hamiltonian describing both radiative and vibrational processes quantum mechanically. We elucidate the extent to which phonon-assisted decay limits the lifetime of a single photon-atom bound state and derive the modified spontaneous emission dynamics due to coupling to various phonon baths. We demonstrate that coherent interaction with undamped phonons can lead to an enhanced lifetime of a photon-atom bound state in a PBG. This results in reduction of the steady-state atomic polarization but an increase in the fractionalized upper state population in the photon-atom bound state. We demonstrate, on the other hand, that the lifetime of the photon-atom bound state in a PBG is limited by the lifetime of phonons due to lattice anharmonicities (breakup of phonons into lower energy phonons) and purely nonradiative decay. We also derive the modified polarization decay and dephasing rates in the presence of such damping. This leads to a microscopic, quantum theory of the optical absorption line shapes. Our model and formalism provide a starting point for describing dephasing and relaxation in the presence of external coherent fields and multiple quantum dot interactions in electromagnetic reservoirs with radiative memory effects.

The dynamics of the optically driven Lambda transition of the 15N-V- center in diamond.

PubMed

González, Gabriel; Leuenberger, Michael N

2010-07-09

Recent experimental results demonstrate the possibility of writing quantum information in the ground state triplet of the (15)N-V(-) center in diamond by means of an optically driven spin non-conserving two-photon Lambda transition in the presence of a strong applied electric field. Our calculations show that the hyperfine interaction in the (15)N-V(-) center is capable of mediating such a transition. We use a density matrix approach to describe the exact dynamics for the allowed optical spin non-conserving transitions between two sublevels of the ground state triplet. This approach allows us to calculate the Rabi oscillations, by means of which we obtain a Rabi frequency with an upper bound determined by the hyperfine interaction. This result is crucial for the success of implementing optically driven quantum information processing with the N-V center in diamond.

Quantum phases of two-component bosons with spin-orbit coupling in optical lattices

NASA Astrophysics Data System (ADS)

Yamamoto, Daisuke; Spielman, I. B.; Sá de Melo, C. A. R.

2017-12-01

Ultracold bosons in optical lattices are one of the few systems where bosonic matter is known to exhibit strong correlations. Here we push the frontier of our understanding of interacting bosons in optical lattices by adding synthetic spin-orbit coupling, and show that new kinds of density and chiral orders develop. The competition between the optical lattice period and the spin-orbit coupling length—which can be made comparable in experiments—along with the spin hybridization induced by a transverse field (i.e., Rabi coupling) and interparticle interactions create a rich variety of quantum phases including uniform, nonuniform, and phase-separated superfluids, as well as Mott insulators. The spontaneous symmetry-breaking phenomena at the transitions between them are explained by a two-order-parameter Ginzburg-Landau model with multiparticle umklapp processes. Finally, in order to characterize each phase, we calculated their experimentally measurable crystal momentum distributions.

A highly efficient silole-containing dithienylethene with excellent thermal stability and fatigue resistance: a promising candidate for optical memory storage materials.

PubMed

Chan, Jacky Chi-Hung; Lam, Wai Han; Yam, Vivian Wing-Wah

2014-12-10

Diarylethene compounds are potential candidates for applications in optical memory storage systems and photoswitchable molecular devices; however, they usually show low photocycloreversion quantum yields, which result in ineffective erasure processes. Here, we present the first highly efficient photochromic silole-containing dithienylethene with excellent thermal stability and fatigue resistance. The photochemical quantum yields for photocyclization and photocycloreversion of the compound are found to be high and comparable to each other; the latter of which is rarely found in diarylethene compounds. These would give rise to highly efficient photoswitchable material with effective writing and erasure processes. Incorporation of the silole moiety as a photochromic dithienylethene backbone also was demonstrated to enhance the thermal stability of the closed form, in which the thermal backward reaction to the open form was found to be negligible even at 100 °C, which leads to a promising candidate for use as photoswitchable materials and optical memory storage.

Quantum synchronization of chaotic oscillator behaviors among coupled BEC-optomechanical systems

NASA Astrophysics Data System (ADS)

Li, Wenlin; Li, Chong; Song, Heshan

2017-03-01

We consider and theoretically analyze a Bose-Einstein condensate (BEC) trapped inside an optomechanical system consisting of single-mode optical cavity with a moving end mirror. The BEC is formally analogous to a mirror driven by radiation pressure with strong nonlinear coupling. Such a nonlinear enhancement can make the oscillator display chaotic behavior. By establishing proper oscillator couplings, we find that this chaotic motion can be synchronized with other oscillators, even an oscillator network. We also discuss the scheme feasibility by analyzing recent experiment parameters. Our results provide a promising platform for the quantum signal transmission and quantum logic control, and they are of potential applications in quantum information processing and quantum networks.

Formation mechanism and optimization of highly luminescent N-doped graphene quantum dots

PubMed Central

Qu, Dan; Zheng, Min; Zhang, Ligong; Zhao, Haifeng; Xie, Zhigang; Jing, Xiabin; Haddad, Raid E.; Fan, Hongyou; Sun, Zaicheng

2014-01-01

Photoluminescent graphene quantum dots (GQDs) have received enormous attention because of their unique chemical, electronic and optical properties. Here a series of GQDs were synthesized under hydrothermal processes in order to investigate the formation process and optical properties of N-doped GQDs. Citric acid (CA) was used as a carbon precursor and self-assembled into sheet structure in a basic condition and formed N-free GQD graphite framework through intermolecular dehydrolysis reaction. N-doped GQDs were prepared using a series of N-containing bases such as urea. Detailed structural and property studies demonstrated the formation mechanism of N-doped GQDs for tunable optical emissions. Hydrothermal conditions promote formation of amide between –NH2 and –COOH with the presence of amine in the reaction. The intramoleculur dehydrolysis between neighbour amide and COOH groups led to formation of pyrrolic N in the graphene framework. Further, the pyrrolic N transformed to graphite N under hydrothermal conditions. N-doping results in a great improvement of PL quantum yield (QY) of GQDs. By optimized reaction conditions, the highest PL QY (94%) of N-doped GQDs was obtained using CA as a carbon source and ethylene diamine as a N source. The obtained N-doped GQDs exhibit an excitation-independent blue emission with single exponential lifetime decay. PMID:24938871

Magneto-optical properties of semi-parabolic plus semi-inverse squared quantum wells

NASA Astrophysics Data System (ADS)

Tung, Luong V.; Vinh, Pham T.; Phuc, Huynh V.

2018-06-01

We theoretically study the optical absorption in a quantum well with the semi-parabolic potential plus the semi-inverse squared potential (SPSIS) in the presence of a static magnetic field in which both one- and two-photon absorption processes have been taken into account. The expression of the magneto-optical absorption coefficient (MOAC) is expressed by the second-order golden rule approximation including the electron-LO phonon interaction. We also use the profile method to obtain the full width at half maximum (FWHM) of the absorption peaks. Our numerical results show that either MOAC or FWHM strongly depends on the confinement frequency, temperature, and magnetic field but their dependence on the parameter β is very weak. The temperature dependence of FWHM is consistent with the previous theoretical and experimental works.

Rare-earth-doped materials with application to optical signal processing, quantum information science, and medical imaging technology

NASA Astrophysics Data System (ADS)

Cone, R. L.; Thiel, C. W.; Sun, Y.; Böttger, Thomas; Macfarlane, R. M.

2012-02-01

Unique spectroscopic properties of isolated rare earth ions in solids offer optical linewidths rivaling those of trapped single atoms and enable a variety of recent applications. We design rare-earth-doped crystals, ceramics, and fibers with persistent or transient "spectral hole" recording properties for applications including high-bandwidth optical signal processing where light and our solids replace the high-bandwidth portion of the electronics; quantum cryptography and information science including the goal of storage and recall of single photons; and medical imaging technology for the 700-900 nm therapeutic window. Ease of optically manipulating rare-earth ions in solids enables capturing complex spectral information in 105 to 108 frequency bins. Combining spatial holography and spectral hole burning provides a capability for processing high-bandwidth RF and optical signals with sub-MHz spectral resolution and bandwidths of tens to hundreds of GHz for applications including range-Doppler radar and high bandwidth RF spectral analysis. Simply stated, one can think of these crystals as holographic recording media capable of distinguishing up to 108 different colors. Ultra-narrow spectral holes also serve as a vibration-insensitive sub-kHz frequency reference for laser frequency stabilization to a part in 1013 over tens of milliseconds. The unusual properties and applications of spectral hole burning of rare earth ions in optical materials are reviewed. Experimental results on the promising Tm3+:LiNbO3 material system are presented and discussed for medical imaging applications. Finally, a new application of these materials as dynamic optical filters for laser noise suppression is discussed along with experimental demonstrations and theoretical modeling of the process.

Single-exciton optical gain in semiconductor nanocrystals.

PubMed

Klimov, Victor I; Ivanov, Sergei A; Nanda, Jagjit; Achermann, Marc; Bezel, Ilya; McGuire, John A; Piryatinski, Andrei

2007-05-24

Nanocrystal quantum dots have favourable light-emitting properties. They show photoluminescence with high quantum yields, and their emission colours depend on the nanocrystal size--owing to the quantum-confinement effect--and are therefore tunable. However, nanocrystals are difficult to use in optical amplification and lasing. Because of an almost exact balance between absorption and stimulated emission in nanoparticles excited with single electron-hole pairs (excitons), optical gain can only occur in nanocrystals that contain at least two excitons. A complication associated with this multiexcitonic nature of light amplification is fast optical-gain decay induced by non-radiative Auger recombination, a process in which one exciton recombines by transferring its energy to another. Here we demonstrate a practical approach for obtaining optical gain in the single-exciton regime that eliminates the problem of Auger decay. Specifically, we develop core/shell hetero-nanocrystals engineered in such a way as to spatially separate electrons and holes between the core and the shell (type-II heterostructures). The resulting imbalance between negative and positive charges produces a strong local electric field, which induces a giant ( approximately 100 meV or greater) transient Stark shift of the absorption spectrum with respect to the luminescence line of singly excited nanocrystals. This effect breaks the exact balance between absorption and stimulated emission, and allows us to demonstrate optical amplification due to single excitons.

Tensor network states in time-bin quantum optics

NASA Astrophysics Data System (ADS)

Lubasch, Michael; Valido, Antonio A.; Renema, Jelmer J.; Kolthammer, W. Steven; Jaksch, Dieter; Kim, M. S.; Walmsley, Ian; García-Patrón, Raúl

2018-06-01

The current shift in the quantum optics community towards experiments with many modes and photons necessitates new classical simulation techniques that efficiently encode many-body quantum correlations and go beyond the usual phase-space formulation. To address this pressing demand we formulate linear quantum optics in the language of tensor network states. We extensively analyze the quantum and classical correlations of time-bin interference in a single fiber loop. We then generalize our results to more complex time-bin quantum setups and identify different classes of architectures for high-complexity and low-overhead boson sampling experiments.

A quantum mechanics-based approach to model incident-induced dynamic driver behavior

NASA Astrophysics Data System (ADS)

Sheu, Jiuh-Biing

2008-08-01

A better understanding of the psychological factors influencing drivers, and the resulting driving behavior responding to incident-induced lane traffic phenomena while passing by an incident site is vital to the improvement of road safety. This paper presents a microscopic driver behavior model to explain the dynamics of the instantaneous driver decision process under lane-blocking incidents on adjacent lanes. The proposed conceptual framework decomposes the corresponding driver decision process into three sequential phases: (1) initial stimulus, (2) glancing-around car-following, and (3) incident-induced driving behavior. The theorem of quantum mechanics in optical flows is applied in the first phase to explain the motion-related perceptual phenomena while vehicles approach the incident site in adjacent lanes, followed by the incorporation of the effect of quantum optical flows in modeling the induced glancing-around car-following behavior in the second phase. Then, an incident-induced driving behavior model is formulated to reproduce the dynamics of driver behavior conducted in the process of passing by an incident site in the adjacent lanes. Numerical results of model tests using video-based incident data indicate the validity of the proposed traffic behavior model in analyzing the incident-induced lane traffic phenomena. It is also expected that such a proposed quantum-mechanics based methodology can throw more light if applied to driver psychology and response in anomalous traffic environments in order to improve road safety.

Second-order nonlinearity induced transparency.

PubMed

Zhou, Y H; Zhang, S S; Shen, H Z; Yi, X X

2017-04-01

In analogy to electromagnetically induced transparency, optomechanically induced transparency was proposed recently in [Science330, 1520 (2010)SCIEAS0036-807510.1126/science.1195596]. In this Letter, we demonstrate another form of induced transparency enabled by second-order nonlinearity. A practical application of the second-order nonlinearity induced transparency is to measure the second-order nonlinear coefficient. Our scheme might find applications in quantum optics and quantum information processing.

Active learning machine learns to create new quantum experiments.

PubMed

Melnikov, Alexey A; Poulsen Nautrup, Hendrik; Krenn, Mario; Dunjko, Vedran; Tiersch, Markus; Zeilinger, Anton; Briegel, Hans J

2018-02-06

How useful can machine learning be in a quantum laboratory? Here we raise the question of the potential of intelligent machines in the context of scientific research. A major motivation for the present work is the unknown reachability of various entanglement classes in quantum experiments. We investigate this question by using the projective simulation model, a physics-oriented approach to artificial intelligence. In our approach, the projective simulation system is challenged to design complex photonic quantum experiments that produce high-dimensional entangled multiphoton states, which are of high interest in modern quantum experiments. The artificial intelligence system learns to create a variety of entangled states and improves the efficiency of their realization. In the process, the system autonomously (re)discovers experimental techniques which are only now becoming standard in modern quantum optical experiments-a trait which was not explicitly demanded from the system but emerged through the process of learning. Such features highlight the possibility that machines could have a significantly more creative role in future research.

Prospects and fundamental limitations of room temperature, non-avalanche, semiconductor photon-counting sensors (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ma, Jiaju; Zhang, Yang; Wang, Xiaoxin; Ying, Lei; Masoodian, Saleh; Wang, Zhiyuan; Starkey, Dakota A.; Deng, Wei; Kumar, Rahul; Wu, Yang; Ghetmiri, Seyed Amir; Yu, Zongfu; Yu, Shui-Qing; Salamo, Gregory J.; Fossum, Eric R.; Liu, Jifeng

2017-05-01

This research investigates the fundamental limits and trade-space of quantum semiconductor photodetectors using the Schrödinger equation and the laws of thermodynamics.We envision that, to optimize the metrics of single photon detection, it is critical to maximize the optical absorption in the minimal volume and minimize the carrier transit process simultaneously. Integration of photon management with quantum charge transport/redistribution upon optical excitation can be engineered to maximize the quantum efficiency (QE) and data rate and minimize timing jitter at the same time. Due to the ultra-low capacitance of these quantum devices, even a single photoelectron transfer can induce a notable change in the voltage, enabling non-avalanche single photon detection at room temperature as has been recently demonstrated in Si quanta image sensors (QIS). In this research, uniform III-V quantum dots (QDs) and Si QIS are used as model systems to test the theory experimentally. Based on the fundamental understanding, we also propose proof-of-concept, photon-managed quantum capacitance photodetectors. Built upon the concepts of QIS and single electron transistor (SET), this novel device structure provides a model system to synergistically test the fundamental limits and tradespace predicted by the theory for semiconductor detectors. This project is sponsored under DARPA/ARO's DETECT Program: Fundamental Limits of Quantum Semiconductor Photodetectors.

Investigation of the quantum efficiency of optical heterodyne detectors

NASA Technical Reports Server (NTRS)

Batchman, T. E.

1984-01-01

The frequency response and quantum efficiency of optical photodetectors for heterodyne receivers is investigated. The measurements utilized two spectral lines from the output of two lasers as input to the photodetectors. These lines are easily measurable in power and frequency and hence serve as known inputs. By measuring the output current of the photodetector the quantum efficiency is determined as a function of frequency separation between the two input signals. An investigation of the theoretical basis and accuracy of this type of measurement relative to similar measurements utilizing risetime is undertaken. A theoretical study of the heterodyne process in photodetectors based on semiconductor physics is included so that higher bandwidth detectors may be designed. All measurements are made on commercially available detectors and manufacturers' specifications for normal photodetector operation are compared to the measured heterodyne characteristics.

Efficient Entanglement Concentration of Nonlocal Two-Photon Polarization-Time-Bin Hyperentangled States

NASA Astrophysics Data System (ADS)

Wang, Zi-Hang; Yu, Wen-Xuan; Wu, Xiao-Yuan; Gao, Cheng-Yan; Alzahrani, Faris; Hobiny, Aatef; Deng, Fu-Guo

2018-03-01

We present two different hyperentanglement concentration protocols (hyper-ECPs) for two-photon systems in nonlocal polarization-time-bin hyperentangled states with known parameters, including Bell-like and cluster-like states, resorting to the parameter splitting method. They require only one of two parties in quantum communication to operate her photon in the process of entanglement concentration, not two, and they have the maximal success probability. They work with linear optical elements and have good feasibility in experiment, especially in the case that there are a big number of quantum data exchanged as the parties can obtain the information about the parameters of the nonlocal hyperentangled states by sampling a subset of nonlocal hyperentangled two-photon systems and measuring them. As the quantum state of photons in the time-bin degree of freedom suffers from less noise in an optical-fiber channel, these hyper-ECPs may have good applications in practical long-distance quantum communication in the future.

Periodically modulated single-photon transport in one-dimensional waveguide

NASA Astrophysics Data System (ADS)

Li, Xingmin; Wei, L. F.

2018-03-01

Single-photon transport along a one-dimension waveguide interacting with a quantum system (e.g., two-level atom) is a very useful and meaningful simplified model of the waveguide-based optical quantum devices. Thus, how to modulate the transport of the photons in the waveguide structures by adjusting certain external parameters should be particularly important. In this paper, we discuss how such a modulation could be implemented by periodically driving the energy splitting of the interacting atom and the atom-photon coupling strength. By generalizing the well developed time-independent full quantum mechanical theory in real space to the time-dependent one, we show that various sideband-transmission phenomena could be observed. This means that, with these modulations the photon has certain probabilities to transmit through the scattering atom in the other energy sidebands. Inversely, by controlling the sideband transmission the periodic modulations of the single photon waveguide devices could be designed for the future optical quantum information processing applications.

Redshift and blueshift of GaNAs/GaAs multiple quantum wells induced by rapid thermal annealing

NASA Astrophysics Data System (ADS)

Sun, Yijun; Cheng, Zhiyuan; Zhou, Qiang; Sun, Ying; Sun, Jiabao; Liu, Yanhua; Wang, Meifang; Cao, Zhen; Ye, Zhi; Xu, Mingsheng; Ding, Yong; Chen, Peng; Heuken, Michael; Egawa, Takashi

2018-02-01

The effects of rapid thermal annealing (RTA) on the optical properties of GaNAs/GaAs multiple quantum wells (MQWs) grown by chemical beam epitaxy (CBE) are studied by photoluminescence (PL) at 77 K. The results show that the optical quality of the MQWs improves significantly after RTA. With increasing RTA temperature, PL peak energy of the MQWs redshifts below 1023 K, while it blueshifts above 1023 K. Two competitive processes which occur simultaneously during RTA result in redshift at low temperature and blueshift at high temperature. It is also found that PL peak energy shift can be explained neither by nitrogen diffusion out of quantum wells nor by nitrogen reorganization inside quantum wells. PL peak energy shift can be quantitatively explained by a modified recombination coupling model in which redshift nonradiative recombination and blueshift nonradiative recombination coexist. The results obtained have significant implication on the growth and RTA of GaNAs material for high performance optoelectronic device application.

Plasmonic giant quantum dots: Hybrid nanostructures for truly simultaneous optical imaging, photothermal effect and thermometry

DOE PAGES

Karan, Niladri S.; Keller, Aaron M.; Sampat, Siddharth; ...

2015-02-09

Hybrid semiconductor–metal nanoscale constructs are of both fundamental and practical interest. Semiconductor nanocrystals are active emitters of photons when stimulated optically, while the interaction of light with nanosized metal objects results in scattering and ohmic damping due to absorption. In a combined structure, the properties of both components can be realized together. At the same time, metal–semiconductor coupling may intervene to modify absorption and/or emission processes taking place in the semiconductor, resulting in a range of effects from photoluminescence quenching to enhancement. We show here that photostable ‘giant’ quantum dots when placed at the center of an ultrathin gold shellmore » retain their key optical property of bright and blinking-free photoluminescence, while the metal shell imparts efficient photothermal transduction. The latter is despite the highly compact total particle size (40–60 nm “inorganic” diameter and <100 nm hydrodynamic diameter) and the very thin nature of the optically transparent Au shell. Furthermore, the sensitivity of the quantum dot emission to local temperature provides a novel internal thermometer for recording temperature during infrared irradiation-induced photothermal heating.« less

Piezoelectric Field Enhanced Second-Order Nonlinear Optical Susceptibilities in Wurtzite GaN/AlGaN Quantum Wells

NASA Technical Reports Server (NTRS)

Liu, Ansheng; Chuang, S.-L.; Ning, C. Z.; Woo, Alex (Technical Monitor)

1999-01-01

Second-order nonlinear optical processes including second-harmonic generation, optical rectification, and difference-frequency generation associated with intersubband transitions in wurtzite GaN/AlGaN quantum well (QW) are investigated theoretically. Taking into account the strain-induced piezoelectric (PZ) effects, we solve the electronic structure of the QW from coupled effective-mass Schrodinger equation and Poisson equation including the exchange-correlation effect under the local-density approximation. We show that the large PZ field in the QW breaks the symmetry of the confinement potential profile and leads to large second-order susceptibilities. We also show that the interband optical pump-induced electron-hole plasma results in an enhancement in the maximum value of the nonlinear coefficients and a redshift of the peak position in the nonlinear optical spectrum. By use of the difference-frequency generation, THz radiation can be generated from a GaN/Al(0.75)Ga(0.25)N with a pump laser of 1.55 micron.

Polarization tracking system for free-space optical communication, including quantum communication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nordholt, Jane Elizabeth; Newell, Raymond Thorson; Peterson, Charles Glen

Quantum communication transmitters include beacon lasers that transmit a beacon optical signal in a predetermined state of polarization such as one of the states of polarization of a quantum communication basis. Changes in the beacon polarization are detected at a receiver, and a retarder is adjusted so that the states of polarization in a received quantum communication optical signal are matched to basis polarizations. The beacon and QC signals can be at different wavelengths so that the beacon does not interfere with detection and decoding of the QC optical signal.

Quantum routing of single optical photons with a superconducting flux qubit

NASA Astrophysics Data System (ADS)

Xia, Keyu; Jelezko, Fedor; Twamley, Jason

2018-05-01

Interconnecting optical photons with superconducting circuits is a challenging problem but essential for building long-range superconducting quantum networks. We propose a hybrid quantum interface between the microwave and optical domains where the propagation of a single-photon pulse along a nanowaveguide is controlled in a coherent way by tuning the electromagnetically induced transparency window with the quantum state of a flux qubit mediated by the spin in a nanodiamond. The qubit can route a single-photon pulse using the nanodiamond into a quantum superposition of paths without the aid of an optical cavity—simplifying the setup. By preparing the flux qubit in a superposition state our cavityless scheme creates a hybrid state-path entanglement between a flying single optical photon and a static superconducting qubit.

Microscopic Studies of Quantum Phase Transitions in Optical Lattices

NASA Astrophysics Data System (ADS)

Bakr, Waseem S.

2011-12-01

In this thesis, I report on experiments that microscopically probe quantum phase transitions of ultracold atoms in optical lattices. We have developed a "quantum gas microscope" that allowed, for the first time, optical imaging and manipulation of single atoms in a quantum-degenerate gas on individual sites of an optical lattice. This system acts as a quantum simulator of strongly correlated materials, which are currently the subject of intense research because of the technological potential of high--T c superconductors and spintronic materials. We have used our microscope to study the superfluid to Mott insulator transition in bosons and a magnetic quantum phase transition in a spin system. In our microscopic study of the superfluid-insulator transition, we have characterized the on-site number statistics in a space- and time-resolved manner. We observed Mott insulators with fidelities as high as 99%, corresponding to entropies of 0.06kB per particle. We also measured local quantum dynamics and directly imaged the shell structure of the Mott insulator. I report on the first quantum magnetism experiments in optical lattices. We have realized a quantum Ising chain in a magnetic field, and observed a quantum phase transition between a paramagnet and antiferromagnet. We achieved strong spin interactions by encoding spins in excitations of a Mott insulator in a tilted lattice. We detected the transition by measuring the total magnetization of the system across the transition using in-situ measurements as well as the Neel ordering in the antiferromagnetic state using noise-correlation techniques. We characterized the dynamics of domain formation in the system. The spin mapping introduced opens up a new path to realizing more exotic states in optical lattices including spin liquids and quantum valence bond solids. As our system sizes become larger, simulating their physics on classical computers will require exponentially larger resources because of entanglement build-up near a quantum phase transition. We have demonstrated a quantum simulator in which all degrees of freedom can be read out microscopically, allowing the simulation of quantum many-body systems with manageable resources. More generally, the ability to image and manipulate individual atoms in optical lattices opens an avenue towards scalable quantum computation.

Trap elimination and reduction of size dispersion due to aging in CdS x Se1- x quantum dots

NASA Astrophysics Data System (ADS)

Verma, Abhishek; Nagpal, Swati; Pandey, Praveen K.; Bhatnagar, P. K.; Mathur, P. C.

2007-12-01

Quantum Dots of CdS x Se1- x embedded in borosilicate glass matrix have been grown using Double-Step annealing method. Optical characterization of the quantum dots has been done through the combinative analysis of optical absorption and photoluminescence spectroscopy at room temperature. Decreasing trend of photoluminescence intensity with aging has been observed and is attributed to trap elimination. The changes in particle size, size distribution, number of quantum dots, volume fraction, trap related phenomenon and Gibbs free energy of quantum dots, has been explained on the basis of the diffusion-controlled growth process, which continues with passage of time. For a typical case, it was found that after 24 months of aging, the average radii increased from 3.05 to 3.12 nm with the increase in number of quantum dots by 190% and the size-dispersion decreased from 10.8% to 9.9%. For this sample, the initial size range of the quantum dots was 2.85 to 3.18 nm. After that no significant change was found in these parameters for the next 12 months. This shows that the system attains almost a stable nature after 24 months of aging. It was also observed that the size-dispersion in quantum dots reduces with the increase in annealing duration, but at the cost of quantum confinement effect. Therefore, a trade off optimization has to be done between the size-dispersion and the quantum confinement.

Optical simulation of quantum algorithms using programmable liquid-crystal displays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puentes, Graciana; La Mela, Cecilia; Ledesma, Silvia

2004-04-01

We present a scheme to perform an all optical simulation of quantum algorithms and maps. The main components are lenses to efficiently implement the Fourier transform and programmable liquid-crystal displays to introduce space dependent phase changes on a classical optical beam. We show how to simulate Deutsch-Jozsa and Grover's quantum algorithms using essentially the same optical array programmed in two different ways.

Mode-Selective Photon Counting Via Quantum Frequency Conversion Using Spectrally-Engineered Pump Pulses

NASA Astrophysics Data System (ADS)

Manurkar, Paritosh

Most of the existing protocols for quantum communication operate in a two-dimensional Hilbert space where their manipulation and measurement have been routinely investigated. Moving to higher-dimensional Hilbert spaces is desirable because of advantages in terms of longer distance communication capabilities, higher channel capacity and better information security. We can exploit the spatio-temporal degrees of freedom for the quantum optical signals to provide the higher-dimensional signals. But this necessitates the need for measurement and manipulation of multidimensional quantum states. To that end, there have been significant theoretical studies based on quantum frequency conversion (QFC) in recent years even though the experimental progress has been limited. QFC is a process that allows preservation of the quantum information while changing the frequency of the input quantum state. It has deservedly garnered a lot of attention because it serves as the connecting bridge between the communications band (C-band near 1550 nm) where the fiber-optic infrastructure is already established and the visible spectrum where high efficiency single-photon detectors and optical memories have been demonstrated. In this experimental work, we demonstrate mode-selective frequency conversion as a means to measure and manipulate photonic signals occupying d -dimensional Hilbert spaces where d=2 and 4. In the d=2 case, we demonstrate mode contrast between two temporal modes (TMs) which serves as the proof-of-concept demonstration. In the d=4 version, we employ six different TMs for our detailed experimental study. These TMs also include superposition modes which are a crucial component in many quantum key distribution protocols. Our method is based on producing pump pulses which allow us to upconvert the TM of interest while ideally preserving the other modes. We use MATLAB simulations to determine the pump pulse shapes which are subsequently produced by controlling the amplitude and phase of each spectral frequency from an optical frequency comb. The latter is generated using a cascaded configuration of phase and amplitude modulators. We characterize the mode selectivity using classical signals by arranging the six TMs into two orthogonal signal sets. Furthermore, we also demonstrate that mode selectivity is preserved if we use sub-photon signals (weak coherent light). Thus, this work supports the idea that QFC has the basic properties needed for advanced multi-dimensional quantum measurements given that we have demonstrated for the first time the ability to move to high dimensions (d=4), measure coherent superposition modes, and measure sub-photon signal levels. In addition to mode-selective photon counting, we also experimentally demonstrate a method of reshaping optical pulses based on QFC. Such a method has the potential to serve as the interface between quantum memories and the existing fiber infrastructure. At the same time, it can be employed in all-optical systems for optical signal regeneration.

Downconversion quantum interface for a single quantum dot spin and 1550-nm single-photon channel.

PubMed

Pelc, Jason S; Yu, Leo; De Greve, Kristiaan; McMahon, Peter L; Natarajan, Chandra M; Esfandyarpour, Vahid; Maier, Sebastian; Schneider, Christian; Kamp, Martin; Höfling, Sven; Hadfield, Robert H; Forchel, Alfred; Yamamoto, Yoshihisa; Fejer, M M

2012-12-03

Long-distance quantum communication networks require appropriate interfaces between matter qubit-based nodes and low-loss photonic quantum channels. We implement a downconversion quantum interface, where the single photons emitted from a semiconductor quantum dot at 910 nm are downconverted to 1560 nm using a fiber-coupled periodically poled lithium niobate waveguide and a 2.2-μm pulsed pump laser. The single-photon character of the quantum dot emission is preserved during the downconversion process: we measure a cross-correlation g(2)(τ = 0) = 0.17 using resonant excitation of the quantum dot. We show that the downconversion interface is fully compatible with coherent optical control of the quantum dot electron spin through the observation of Rabi oscillations in the downconverted photon counts. These results represent a critical step towards a long-distance hybrid quantum network in which subsystems operating at different wavelengths are connected through quantum frequency conversion devices and 1.5-μm quantum channels.

Quantum plasmonic sensing

DOE PAGES

Fan, Wenjiang; Lawrie, Benjamin J.; Pooser, Raphael C.

2015-11-04

Surface plasmon resonance (SPR) sensors can reach the quantum noise limit of the optical readout field in various configurations. We demonstrate that two-mode intensity squeezed states produce a further enhancement in sensitivity compared with a classical optical readout when the quantum noise is used to transduce an SPR sensor signal in the Kretschmann configuration. The quantum noise reduction between the twin beams when incident at an angle away from the plasmonic resonance, combined with quantum noise resulting from quantum anticorrelations when on resonance, results in an effective SPR-mediated modulation that yields a measured sensitivity 5 dB better than that withmore » a classical optical readout in this configuration. Furthermore, the theoretical potential of this technique points to resolving particle concentrations with more accuracy than is possible via classical approaches to optical transduction.« less

Capacities of quantum amplifier channels

NASA Astrophysics Data System (ADS)

Qi, Haoyu; Wilde, Mark M.

2017-01-01

Quantum amplifier channels are at the core of several physical processes. Not only do they model the optical process of spontaneous parametric down-conversion, but the transformation corresponding to an amplifier channel also describes the physics of the dynamical Casimir effect in superconducting circuits, the Unruh effect, and Hawking radiation. Here we study the communication capabilities of quantum amplifier channels. Invoking a recently established minimum output-entropy theorem for single-mode phase-insensitive Gaussian channels, we determine capacities of quantum-limited amplifier channels in three different scenarios. First, we establish the capacities of quantum-limited amplifier channels for one of the most general communication tasks, characterized by the trade-off between classical communication, quantum communication, and entanglement generation or consumption. Second, we establish capacities of quantum-limited amplifier channels for the trade-off between public classical communication, private classical communication, and secret key generation. Third, we determine the capacity region for a broadcast channel induced by the quantum-limited amplifier channel, and we also show that a fully quantum strategy outperforms those achieved by classical coherent-detection strategies. In all three scenarios, we find that the capacities significantly outperform communication rates achieved with a naive time-sharing strategy.

Multi-functional quantum router using hybrid opto-electromechanics

NASA Astrophysics Data System (ADS)

Ma, Peng-Cheng; Yan, Lei-Lei; Chen, Gui-Bin; Li, Xiao-Wei; Liu, Shu-Jing; Zhan, You-Bang

2018-03-01

Quantum routers engineered with multiple frequency bands play a key role in quantum networks. We propose an experimentally accessible scheme for a multi-functional quantum router, using photon-phonon conversion in a hybrid opto-electromechanical system. Our proposed device functions as a bidirectional, tunable multi-channel quantum router, and demonstrates the possibility to route single optical photons bidirectionally and simultaneously to three different output ports, by adjusting the microwave power. Further, the device also behaves as an interswitching unit for microwave and optical photons, yielding probabilistic routing of microwave (optical) signals to optical (microwave) outports. With respect to potential application, we verify the insignificant influence from vacuum and thermal noises in the performance of the router under cryogenic conditions.

Continuous-Variable Triple-Photon States Quantum Entanglement

NASA Astrophysics Data System (ADS)

González, E. A. Rojas; Borne, A.; Boulanger, B.; Levenson, J. A.; Bencheikh, K.

2018-01-01

We investigate the quantum entanglement of the three modes associated with the three-photon states obtained by triple-photon generation in a phase-matched third-order nonlinear optical interaction. Although the second-order processes have been extensively dealt with, there is no direct analogy between the second and third-order mechanisms. We show, for example, the absence of quantum entanglement between the quadratures of the three modes in the case of spontaneous parametric triple-photon generation. However, we show robust, seeding-dependent, genuine triple-photon entanglement in the fully seeded case.

Continuous-Variable Triple-Photon States Quantum Entanglement.

PubMed

González, E A Rojas; Borne, A; Boulanger, B; Levenson, J A; Bencheikh, K

2018-01-26

We investigate the quantum entanglement of the three modes associated with the three-photon states obtained by triple-photon generation in a phase-matched third-order nonlinear optical interaction. Although the second-order processes have been extensively dealt with, there is no direct analogy between the second and third-order mechanisms. We show, for example, the absence of quantum entanglement between the quadratures of the three modes in the case of spontaneous parametric triple-photon generation. However, we show robust, seeding-dependent, genuine triple-photon entanglement in the fully seeded case.

Classical and quantum optical correlation effects between single quantum dots: The role of the hopping photon

NASA Astrophysics Data System (ADS)

Hughes, S.; Gotoh, H.; Kamada, H.

2006-09-01

We present a theoretical study of photon-coupled single quantum dots in a semiconductor. A series of optical effects are demonstrated, including a subradiant dark resonance, superradiance, reversible spontaneous emission decay, and pronounced exciton entanglement. Both classical and quantum optical approaches are presented using a self-consistent formalism that treats real and virtual photon exchange on an equal footing and can account for different quantum dot properties, surface effects, and retardation in the dipole-dipole coupling, all of which are shown to play a non-negligible role.

Non-local classical optical correlation and implementing analogy of quantum teleportation

PubMed Central

Sun, Yifan; Song, Xinbing; Qin, Hongwei; Zhang, Xiong; Yang, Zhenwei; Zhang, Xiangdong

2015-01-01

This study reports an experimental realization of non-local classical optical correlation from the Bell's measurement used in tests of quantum non-locality. Based on such a classical Einstein–Podolsky–Rosen optical correlation, a classical analogy has been implemented to the true meaning of quantum teleportation. In the experimental teleportation protocol, the initial teleported information can be unknown to anyone and the information transfer can happen over arbitrary distances. The obtained results give novel insight into quantum physics and may open a new field of applications in quantum information. PMID:25779977

All optical quantum control of a spin-quantum state and ultrafast transduction into an electric current.

PubMed

Müller, K; Kaldewey, T; Ripszam, R; Wildmann, J S; Bechtold, A; Bichler, M; Koblmüller, G; Abstreiter, G; Finley, J J

2013-01-01

The ability to control and exploit quantum coherence and entanglement drives research across many fields ranging from ultra-cold quantum gases to spin systems in condensed matter. Transcending different physical systems, optical approaches have proven themselves to be particularly powerful, since they profit from the established toolbox of quantum optical techniques, are state-selective, contact-less and can be extremely fast. Here, we demonstrate how a precisely timed sequence of monochromatic ultrafast (~ 2-5 ps) optical pulses, with a well defined polarisation can be used to prepare arbitrary superpositions of exciton spin states in a semiconductor quantum dot, achieve ultrafast control of the spin-wavefunction without an applied magnetic field and make high fidelity read-out the quantum state in an arbitrary basis simply by detecting a strong (~ 2-10 pA) electric current flowing in an external circuit. The results obtained show that the combined quantum state preparation, control and read-out can be performed with a near-unity (≥97%) fidelity.

Conceptual designs of onboard transceivers for ground-to-satellite quantum cryptography

NASA Astrophysics Data System (ADS)

Toyoshima, Morio; Shoji, Yozo; Takayama, Yoshihisa; Kunimori, Hiroo; Takeoka, Masahiro; Fujiwara, Mikio; Sasaki, Masahide

2009-05-01

A free-space quantum key distribution system is being developed by the National Institute of Information and Communications Technology (NICT) in Koganei, Japan. Quantum cryptography is a new technique for transmitting information where the security is guaranteed by the laws of physics. In such systems, a single photon is used for the quantum information. However, since the transmission distance in optical fibers is limited by the absorption of photons by the fiber, the maximum demonstrated range has been limited to about 100 km. Free-space quantum cryptography between an optical ground station and a satellite is a possible solution to extend the distance for a quantum network beyond the limits of optical fibers. At NICT, a laser communication demonstration between the NICT optical ground station and a low earth orbit satellite was successfully conducted in 2006. The use of free-space quantum key distribution for such space communication links is considered an important future application. This paper presents conceptual designs for the onboard transceivers for satellite quantum cryptography

Experimental demonstration of a flexible time-domain quantum channel.

PubMed

Xing, Xingxing; Feizpour, Amir; Hayat, Alex; Steinberg, Aephraim M

2014-10-20

We present an experimental realization of a flexible quantum channel where the Hilbert space dimensionality can be controlled electronically. Using electro-optical modulators (EOM) and narrow-band optical filters, quantum information is encoded and decoded in the temporal degrees of freedom of photons from a long-coherence-time single-photon source. Our results demonstrate the feasibility of a generic scheme for encoding and transmitting multidimensional quantum information over the existing fiber-optical telecommunications infrastructure.

Tunable Emission Wavelength Stacked InAs/GaAs Quantum Dots by Chemical Beam Epitaxy for Optical Coherence Tomography

PubMed Central

Ilahi, Bouraoui; Zribi, Jihene; Guillotte, Maxime; Arès, Richard; Aimez, Vincent; Morris, Denis

2016-01-01

We report on Chemical Beam Epitaxy (CBE) growth of wavelength tunable InAs/GaAs quantum dots (QD) based superluminescent diode’s active layer suitable for Optical Coherence Tomography (OCT). The In-flush technique has been employed to fabricate QD with controllable heights, from 5 nm down to 2 nm, allowing a tunable emission band over 160 nm. The emission wavelength blueshift has been ensured by reducing both dots’ height and composition. A structure containing four vertically stacked height-engineered QDs have been fabricated, showing a room temperature broad emission band centered at 1.1 µm. The buried QD layers remain insensitive to the In-flush process of the subsequent layers, testifying the reliability of the process for broadband light sources required for high axial resolution OCT imaging. PMID:28773633

Hybrid plasmonic systems: from optical transparencies to strong coupling and entanglement

NASA Astrophysics Data System (ADS)

Gray, Stephen K.

2018-02-01

Classical electrodynamics and quantum mechanical models of quantum dots and molecules interacting with plasmonic systems are discussed. Calculations show that just one quantum dot interacting with a plasmonic system can lead to interesting optical effects, including optical transparencies and more general Fano resonance features that can be tailored with ultrafast laser pulses. Such effects can occur in the limit of moderate coupling between quantum dot and plasmonic system. The approach to the strong coupling regime is also discussed. In cases with two or more quantum dots within a plasmonic system, the possibility of quantum entanglement mediated through the dissipative plasmonic structure arises.

Spin-based single-photon transistor, dynamic random access memory, diodes, and routers in semiconductors

NASA Astrophysics Data System (ADS)

Hu, C. Y.

2016-12-01

The realization of quantum computers and quantum Internet requires not only quantum gates and quantum memories, but also transistors at single-photon levels to control the flow of information encoded on single photons. Single-photon transistor (SPT) is an optical transistor in the quantum limit, which uses a single photon to open or block a photonic channel. In sharp contrast to all previous SPT proposals which are based on single-photon nonlinearities, here I present a design for a high-gain and high-speed (up to THz) SPT based on a linear optical effect: giant circular birefringence induced by a single spin in a double-sided optical microcavity. A gate photon sets the spin state via projective measurement and controls the light propagation in the optical channel. This spin-cavity transistor can be directly configured as diodes, routers, DRAM units, switches, modulators, etc. Due to the duality as quantum gate and transistor, the spin-cavity unit provides a solid-state platform ideal for future Internet: a mixture of all-optical Internet with quantum Internet.

Stimulated Emission of Terahertz Radiation from Internal ExcitonTransitions in Cu2O

NASA Astrophysics Data System (ADS)

Schmid, B. A.; Huber, R.; Shen, Y. R.; Kaindl, R. A.; Chemla, D. S.

2006-03-01

Excitons are among the most fundamental optical excitation modes in semiconductors. Resonant infrared pulses have been used to sensitively probe absorptive transitions between hydrogen-like bound pair states [1,2]. We report the first observation of the reverse quantum process: stimulated emission of electromagnetic radiation from intra-excitonic transitions [3]. Broadband terahertz pulses monitor the far-infrared electromagnetic response of Cu2O after ultrafast resonant photogeneration of 3p excitons. Stimulated emission from the 3p to the energetically lower 2s bound level occurs at a photon energy of 6.6 meV, with a cross section of ˜10-14 cm^2. Simultaneous excitation of both exciton levels, in turn, drives quantum beats which lead to efficient terahertz emission sharply peaked at the difference frequency. Our results demonstrate a new fundamental process of THz quantum optics and highlight analogies and differences between excitonic and atomic systems. [1] R. A. Kaindl et al., Nature 423, 734 (2003). [2] M. Kubouchi et al., Phys. Rev. Lett. 94, 016403 (2005). [3] R. Huber et al., Phys. Rev. Lett., to appear.

Information trade-offs for optical quantum communication.

PubMed

Wilde, Mark M; Hayden, Patrick; Guha, Saikat

2012-04-06

Recent work has precisely characterized the achievable trade-offs between three key information processing tasks-classical communication (generation or consumption), quantum communication (generation or consumption), and shared entanglement (distribution or consumption), measured in bits, qubits, and ebits per channel use, respectively. Slices and corner points of this three-dimensional region reduce to well-known protocols for quantum channels. A trade-off coding technique can attain any point in the region and can outperform time sharing between the best-known protocols for accomplishing each information processing task by itself. Previously, the benefits of trade-off coding that had been found were too small to be of practical value (viz., for the dephasing and the universal cloning machine channels). In this Letter, we demonstrate that the associated performance gains are in fact remarkably high for several physically relevant bosonic channels that model free-space or fiber-optic links, thermal-noise channels, and amplifiers. We show that significant performance gains from trade-off coding also apply when trading photon-number resources between transmitting public and private classical information simultaneously over secret-key-assisted bosonic channels. © 2012 American Physical Society

The impact of quantum dot filling on dual-band optical transitions via intermediate quantum states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Jiang, E-mail: jiang.wu@ucl.ac.uk; Passmore, Brandon; Manasreh, M. O.

2015-08-28

InAs/GaAs quantum dot infrared photodetectors with different doping levels were investigated to understand the effect of quantum dot filling on both intraband and interband optical transitions. The electron filling of self-assembled InAs quantum dots was varied by direct doping of quantum dots with different concentrations. Photoresponse in the near infrared and middle wavelength infrared spectral region was observed from samples with low quantum dot filling. Although undoped quantum dots were favored for interband transitions with the absence of a second optical excitation in the near infrared region, doped quantum dots were preferred to improve intraband transitions in the middle wavelengthmore » infrared region. As a result, partial filling of quantum dot was required, to the extent of maintaining a low dark current, to enhance the dual-band photoresponse through the confined electron states.« less

On-Chip Single-Plasmon Nanocircuit Driven by a Self-Assembled Quantum Dot.

PubMed

Wu, Xiaofei; Jiang, Ping; Razinskas, Gary; Huo, Yongheng; Zhang, Hongyi; Kamp, Martin; Rastelli, Armando; Schmidt, Oliver G; Hecht, Bert; Lindfors, Klas; Lippitz, Markus

2017-07-12

Quantum photonics holds great promise for future technologies such as secure communication, quantum computation, quantum simulation, and quantum metrology. An outstanding challenge for quantum photonics is to develop scalable miniature circuits that integrate single-photon sources, linear optical components, and detectors on a chip. Plasmonic nanocircuits will play essential roles in such developments. However, for quantum plasmonic circuits, integration of stable, bright, and narrow-band single photon sources in the structure has so far not been reported. Here we present a plasmonic nanocircuit driven by a self-assembled GaAs quantum dot. Through a planar dielectric-plasmonic hybrid waveguide, the quantum dot efficiently excites narrow-band single plasmons that are guided in a two-wire transmission line until they are converted into single photons by an optical antenna. Our work demonstrates the feasibility of fully on-chip plasmonic nanocircuits for quantum optical applications.

Training Schrödinger's cat: quantum optimal control. Strategic report on current status, visions and goals for research in Europe

NASA Astrophysics Data System (ADS)

Glaser, Steffen J.; Boscain, Ugo; Calarco, Tommaso; Koch, Christiane P.; Köckenberger, Walter; Kosloff, Ronnie; Kuprov, Ilya; Luy, Burkhard; Schirmer, Sophie; Schulte-Herbrüggen, Thomas; Sugny, Dominique; Wilhelm, Frank K.

2015-12-01

It is control that turns scientific knowledge into useful technology: in physics and engineering it provides a systematic way for driving a dynamical system from a given initial state into a desired target state with minimized expenditure of energy and resources. As one of the cornerstones for enabling quantum technologies, optimal quantum control keeps evolving and expanding into areas as diverse as quantum-enhanced sensing, manipulation of single spins, photons, or atoms, optical spectroscopy, photochemistry, magnetic resonance (spectroscopy as well as medical imaging), quantum information processing and quantum simulation. In this communication, state-of-the-art quantum control techniques are reviewed and put into perspective by a consortium of experts in optimal control theory and applications to spectroscopy, imaging, as well as quantum dynamics of closed and open systems. We address key challenges and sketch a roadmap for future developments.

Deterministic quantum teleportation of atomic qubits.

PubMed

Barrett, M D; Chiaverini, J; Schaetz, T; Britton, J; Itano, W M; Jost, J D; Knill, E; Langer, C; Leibfried, D; Ozeri, R; Wineland, D J

2004-06-17

Quantum teleportation provides a means to transport quantum information efficiently from one location to another, without the physical transfer of the associated quantum-information carrier. This is achieved by using the non-local correlations of previously distributed, entangled quantum bits (qubits). Teleportation is expected to play an integral role in quantum communication and quantum computation. Previous experimental demonstrations have been implemented with optical systems that used both discrete and continuous variables, and with liquid-state nuclear magnetic resonance. Here we report unconditional teleportation of massive particle qubits using atomic (9Be+) ions confined in a segmented ion trap, which aids individual qubit addressing. We achieve an average fidelity of 78 per cent, which exceeds the fidelity of any protocol that does not use entanglement. This demonstration is also important because it incorporates most of the techniques necessary for scalable quantum information processing in an ion-trap system.

Quantum storage of heralded polarization qubits in birefringent and anisotropically absorbing materials.

PubMed

Clausen, Christoph; Bussières, Félix; Afzelius, Mikael; Gisin, Nicolas

2012-05-11

Storage of quantum information encoded into heralded single photons is an essential constituent of long-distance quantum communication based on quantum repeaters and of optical quantum information processing. The storage of photonic polarization qubits is, however, difficult because many materials are birefringent and have polarization-dependent absorption. Here we present a simple scheme that eliminates these polarization effects, and we demonstrate it by storing heralded polarization qubits into a solid-state quantum memory. The quantum memory is implemented with a biaxial yttrium orthosilicate (Y2SiO5) crystal doped with rare-earth ions. Heralded single photons generated from a filtered spontaneous parametric down-conversion source are stored, and quantum state tomography of the retrieved polarization state reveals an average fidelity of 97.5±0.4%, which is significantly higher than what is achievable with a measure-and-prepare strategy.

Quantum amplification and quantum optical tapping with squeezed states and correlated quantum states

NASA Technical Reports Server (NTRS)

Ou, Z. Y.; Pereira, S. F.; Kimble, H. J.

1994-01-01

Quantum fluctuations in a nondegenerate optical parametric amplifier (NOPA) are investigated experimentally with a squeezed state coupled into the internal idler mode of the NOPA. Reductions of the inherent quantum noise of the amplifier are observed with a minimum noise level 0.7 dB below the usual noise level of the amplifier with its idler mode in a vacuum state. With two correlated quantum fields as the amplifier's inputs and proper adjustment of the gain of the amplifier, it is shown that the amplifier's intrinsic quantum noise can be completely suppressed so that noise-free amplification is achieved. It is also shown that the NOPA, when coupled to either a squeezed state or a nonclassically correlated state, can realize quantum tapping of optical information.

Nuclear Spin Nanomagnet in an Optically Excited Quantum Dot

NASA Astrophysics Data System (ADS)

Korenev, V. L.

2007-12-01

Linearly polarized light tuned slightly below the optical transition of the negatively charged exciton (trion) in a single quantum dot causes the spontaneous nuclear spin polarization (self-polarization) at a level close to 100%. The effective magnetic field of spin-polarized nuclei shifts the optical transition energy close to resonance with photon energy. The resonantly enhanced Overhauser effect sustains the stability of the nuclear self-polarization even in the absence of spin polarization of the quantum dot electron. As a result the optically selected single quantum dot represents a tiny magnet with the ferromagnetic ordering of nuclear spins—the nuclear spin nanomagnet.

Optical pumping of the electronic and nuclear spin of single charge-tunable quantum dots.

PubMed

Bracker, A S; Stinaff, E A; Gammon, D; Ware, M E; Tischler, J G; Shabaev, A; Efros, Al L; Park, D; Gershoni, D; Korenev, V L; Merkulov, I A

2005-02-04

We present a comprehensive examination of optical pumping of spins in individual GaAs quantum dots as we change the net charge from positive to neutral to negative with a charge-tunable heterostructure. Negative photoluminescence polarization memory is enhanced by optical pumping of ground state electron spins, which we prove with the first measurements of the Hanle effect on an individual quantum dot. We use the Overhauser effect in a high longitudinal magnetic field to demonstrate efficient optical pumping of nuclear spins for all three charge states of the quantum dot.

Optical Pumping of the Electronic and Nuclear Spin of Single Charge-Tunable Quantum Dots

NASA Astrophysics Data System (ADS)

Bracker, A. S.; Stinaff, E. A.; Gammon, D.; Ware, M. E.; Tischler, J. G.; Shabaev, A.; Efros, Al. L.; Park, D.; Gershoni, D.; Korenev, V. L.; Merkulov, I. A.

2005-02-01

We present a comprehensive examination of optical pumping of spins in individual GaAs quantum dots as we change the net charge from positive to neutral to negative with a charge-tunable heterostructure. Negative photoluminescence polarization memory is enhanced by optical pumping of ground state electron spins, which we prove with the first measurements of the Hanle effect on an individual quantum dot. We use the Overhauser effect in a high longitudinal magnetic field to demonstrate efficient optical pumping of nuclear spins for all three charge states of the quantum dot.

Nuclear spin nanomagnet in an optically excited quantum dot.

PubMed

Korenev, V L

2007-12-21

Linearly polarized light tuned slightly below the optical transition of the negatively charged exciton (trion) in a single quantum dot causes the spontaneous nuclear spin polarization (self-polarization) at a level close to 100%. The effective magnetic field of spin-polarized nuclei shifts the optical transition energy close to resonance with photon energy. The resonantly enhanced Overhauser effect sustains the stability of the nuclear self-polarization even in the absence of spin polarization of the quantum dot electron. As a result the optically selected single quantum dot represents a tiny magnet with the ferromagnetic ordering of nuclear spins-the nuclear spin nanomagnet.

When quantum optics meets topology

NASA Astrophysics Data System (ADS)

Amo, Alberto

2018-02-01

Routing photons at the micrometer scale remains one of the greatest challenges of integrated quantum optics. The main difficulty is the scattering losses at bends and splitters in the photonic circuit. Current approaches imply elaborate designs, quite sensitive to fabrication details (1). Inspired by the physics underlying the one-way transport of electrons in topological insulators, on page 666 of this issue, Barik et al. (2) report a topological photonic crystal in which single photons are emitted and routed through bends with negligible loss. The marriage between quantum optics and topology promises new opportunities for compact quantum optics gating and manipulation.

Self-consistent projection operator theory in nonlinear quantum optical systems: A case study on degenerate optical parametric oscillators

NASA Astrophysics Data System (ADS)

Degenfeld-Schonburg, Peter; Navarrete-Benlloch, Carlos; Hartmann, Michael J.

2015-05-01

Nonlinear quantum optical systems are of paramount relevance for modern quantum technologies, as well as for the study of dissipative phase transitions. Their nonlinear nature makes their theoretical study very challenging and hence they have always served as great motivation to develop new techniques for the analysis of open quantum systems. We apply the recently developed self-consistent projection operator theory to the degenerate optical parametric oscillator to exemplify its general applicability to quantum optical systems. We show that this theory provides an efficient method to calculate the full quantum state of each mode with a high degree of accuracy, even at the critical point. It is equally successful in describing both the stationary limit and the dynamics, including regions of the parameter space where the numerical integration of the full problem is significantly less efficient. We further develop a Gaussian approach consistent with our theory, which yields sensibly better results than the previous Gaussian methods developed for this system, most notably standard linearization techniques.

Nanofiber quantum photonics

NASA Astrophysics Data System (ADS)

Nayak, Kali P.; Sadgrove, Mark; Yalla, Ramachandrarao; Le Kien, Fam; Hakuta, Kohzo

2018-07-01

Recent advances in the coherent control of single quanta of light, photons, is a topic of prime interest, and is discussed under the banner of quantum photonics. In the last decade, the subwavelength diameter waist of a tapered optical fiber, referred to as an optical nanofiber, has opened promising new avenues in the field of quantum optics, paving the way toward a versatile platform for quantum photonics applications. The key feature of the technique is that the optical field can be tightly confined in the transverse direction while propagating over long distances as a guided mode and enabling strong interaction with the surrounding medium in the evanescent region. This feature has led to surprising possibilities to manipulate single atoms and fiber-guided photons, e.g. the efficient channeling of emission from single atoms and solid-state quantum emitters into the fiber-guided modes, high optical depth with a few atoms around the nanofiber, trapping atoms around a nanofiber, and atomic memories for fiber-guided photons. Furthermore, implementing a moderate longitudinal confinement in nanofiber cavities has enabled the strong coupling regime of cavity quantum electrodynamics to be reached, and the long-range dipole–dipole interaction between quantum emitters mediated by the nanofiber offers a platform for quantum nonlinear optics with an ensemble of atoms. In addition, the presence of a longitudinal component of the guided field has led to unique capabilities for chiral light–matter interactions on nanofibers. In this article, we review the key developments of the nanofiber technology toward a vision for quantum photonics on an all-fiber interface.

High-Performance, Solution-Processed Quantum Dot Light-Emitting Field-Effect Transistors with a Scandium-Incorporated Indium Oxide Semiconductor.

PubMed

He, Penghui; Jiang, Congbiao; Lan, Linfeng; Sun, Sheng; Li, Yizhi; Gao, Peixiong; Zhang, Peng; Dai, Xingqiang; Wang, Jian; Peng, Junbiao; Cao, Yong

2018-05-22

Light-emitting field-effect transistors (LEFETs) have attained great attention due to their special characteristics of both the switching capacity and the electroluminescence capacity. However, high-performance LEFETs with high mobility, high brightness, and high efficiency have not been realized due to the difficulty in developing high electron and hole mobility materials with suitable band structures. In this paper, quantum dot hybrid LEFETs (QD-HLEFETs) combining high-luminous-efficiency quantum dots (QDs) and a solution-processed scandium-incorporated indium oxide (Sc:In 2 O 3 ) semiconductor were demonstrated. The red QD-HLEFET showed high electrical and optical performance with an electron mobility of 0.8 cm 2 V -1 s -1 , a maximum brightness of 13 400 cd/m 2 , and a maximum external quantum efficiency of 8.7%. The high performance of the QD-HLEFET is attributed to the good energy band matching between Sc:In 2 O 3 and QDs and the balanced hole and electron injection (less exciton nonradiative recombination). In addition, incorporation of Sc into In 2 O 3 can suppress the oxygen vacancy and free carrier generation and brings about excellent current and optical modulation (the on/off current ratio is 10 5 and the on/off brightness ratio is 10 6 ).

A comparison of the optical properties of InGaN/GaN multiple quantum well structures grown with and without Si-doped InGaN prelayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davies, M. J., E-mail: Matthew.Davies-2@Manchester.ac.uk; Hammersley, S.; Dawson, P.

In this paper, we report on a detailed spectroscopic study of the optical properties of InGaN/GaN multiple quantum well structures, both with and without a Si-doped InGaN prelayer. In photoluminescence and photoluminescence excitation spectroscopy, a 2nd emission band, occurring at a higher energy, was identified in the spectrum of the multiple quantum well structure containing the InGaN prelayer, originating from the first quantum well in the stack. Band structure calculations revealed that a reduction in the resultant electric field occurred in the quantum well immediately adjacent to the InGaN prelayer, therefore leading to a reduction in the strength of themore » quantum confined Stark effect in this quantum well. The partial suppression of the quantum confined Stark effect in this quantum well led to a modified (higher) emission energy and increased radiative recombination rate. Therefore, we ascribed the origin of the high energy emission band to recombination from the 1st quantum well in the structure. Study of the temperature dependent recombination dynamics of both samples showed that the decay time measured across the spectrum was strongly influenced by the 1st quantum well in the stack (in the sample containing the prelayer) leading to a shorter average room temperature lifetime in this sample. The room temperature internal quantum efficiency of the prelayer containing sample was found to be higher than the reference sample (36% compared to 25%) which was thus attributed to the faster radiative recombination rate of the 1st quantum well providing a recombination pathway that is more competitive with non-radiative recombination processes.« less

Quantum and classical properties of soliton propagation in optical fibers

NASA Astrophysics Data System (ADS)

Krylov, Dmitriy

2001-05-01

Quantum and classical aspects of nonlinear optical pulse propagation in optical fibers are studied with the emphasis on temporal solitons. The theoretical and experimental investigation focuses on phenomena that can fundamentally limit transmission and detection of optical signals in fiber-optic communication systems that employ solitons. In transmission experiments the first evidence is presented that a pre-chirped high-order soliton pulse propagating in a low anomalous dispersion optical fiber will irreversibly break up into an ordered train of fundamental (N = 1) solitons. The experimental results confirm previous analytical predictions and show excellent agreement with numerical simulations. This phenomenon presents a fundamental limitation on systems that utilize dispersion-management or pre-chirping of optical pulses, and has to be taken into consideration when designing such systems. The experiments also show that the breakup process can be repeated by cascading two independent breakup stages. Each stage accepts a single input pulse and produces two independent pulses. The stages are cascaded to produce a one-to-four breakup. Solitons are also shown to be ideally suited for investigating non-classical properties of light. Based on the general quantum theory of optical pulse propagation, a new scheme for generating amplitude-squeezed solitons is designed and implemented in a highly asymmetric fiber Sagnac interferometer. A record reduction of 5.7dB (73%) and, with correction for linear losses, 7.0dB (81%) in photon-number fluctuations below the shot-noise level is measured by direct detection. The same scheme is also shown to generate significant classical noise reduction and is limited by Raman effects in fiber. Such large squeezing levels can be employed in practical fiber optic communication systems to achieve noiseless amplification and better signal to noise ratios in direct detection. The photon number states can also be used in quantum non- demolition measurements and quantum communications. Amplitude squeezing is shown to be present in the normal- dispersion regime where no soliton formation is possible. In this case, a noise reduction of 1.7dB (33%) and, with correction for linear losses, 2.5dB (47%) below the shot- noise level is measured. The dependence of noise behavior on dispersion is investigated both experimentally and theoretically.

Quantum cryptography and applications in the optical fiber network

NASA Astrophysics Data System (ADS)

Luo, Yuhui

2005-09-01

Quantum cryptography, as part of quantum information and communications, can provide absolute security for information transmission because it is established on the fundamental laws of quantum theory, such as the principle of uncertainty, No-cloning theorem and quantum entanglement. In this thesis research, a novel scheme to implement quantum key distribution based on multiphoton entanglement with a new protocol is proposed. Its advantages are: a larger information capacity can be obtained with a longer transmission distance and the detection of multiple photons is easier than that of a single photon. The security and attacks pertaining to such a system are also studied. Next, a quantum key distribution over wavelength division multiplexed (WDM) optical fiber networks is realized. Quantum key distribution in networks is a long-standing problem for practical applications. Here we combine quantum cryptography and WDM to solve this problem because WDM technology is universally deployed in the current and next generation fiber networks. The ultimate target is to deploy quantum key distribution over commercial networks. The problems arising from the networks are also studied in this part. Then quantum key distribution in multi-access networks using wavelength routing technology is investigated in this research. For the first time, quantum cryptography for multiple individually targeted users has been successfully implemented in sharp contrast to that using the indiscriminating broadcasting structure. It overcomes the shortcoming that every user in the network can acquire the quantum key signals intended to be exchanged between only two users. Furthermore, a more efficient scheme of quantum key distribution is adopted, hence resulting in a higher key rate. Lastly, a quantum random number generator based on quantum optics has been experimentally demonstrated. This device is a key component for quantum key distribution as it can create truly random numbers, which is an essential requirement to perform quantum key distribution. This new generator is composed of a single optical fiber coupler with fiber pigtails, which can be easily used in optical fiber communications.

Linear Optics Simulation of Quantum Non-Markovian Dynamics

PubMed Central

Chiuri, Andrea; Greganti, Chiara; Mazzola, Laura; Paternostro, Mauro; Mataloni, Paolo

2012-01-01

The simulation of open quantum dynamics has recently allowed the direct investigation of the features of system-environment interaction and of their consequences on the evolution of a quantum system. Such interaction threatens the quantum properties of the system, spoiling them and causing the phenomenon of decoherence. Sometimes however a coherent exchange of information takes place between system and environment, memory effects arise and the dynamics of the system becomes non-Markovian. Here we report the experimental realisation of a non-Markovian process where system and environment are coupled through a simulated transverse Ising model. By engineering the evolution in a photonic quantum simulator, we demonstrate the role played by system-environment correlations in the emergence of memory effects. PMID:23236588

Method and apparatus for quantum information processing using entangled neutral-atom qubits

DOEpatents

Jau, Yuan Yu; Biedermann, Grant; Deutsch, Ivan

2018-04-03

A method for preparing an entangled quantum state of an atomic ensemble is provided. The method includes loading each atom of the atomic ensemble into a respective optical trap; placing each atom of the atomic ensemble into a same first atomic quantum state by impingement of pump radiation; approaching the atoms of the atomic ensemble to within a dipole-dipole interaction length of each other; Rydberg-dressing the atomic ensemble; during the Rydberg-dressing operation, exciting the atomic ensemble with a Raman pulse tuned to stimulate a ground-state hyperfine transition from the first atomic quantum state to a second atomic quantum state; and separating the atoms of the atomic ensemble by more than a dipole-dipole interaction length.

Optical Fiber Sensing Using Quantum Dots

PubMed Central

Jorge, Pedro; Martins, Manuel António; Trindade, Tito; Santos, José Luís; Farahi, Faramarz

2007-01-01

Recent advances in the application of semiconductor nanocrystals, or quantum dots, as biochemical sensors are reviewed. Quantum dots have unique optical properties that make them promising alternatives to traditional dyes in many luminescence based bioanalytical techniques. An overview of the more relevant progresses in the application of quantum dots as biochemical probes is addressed. Special focus will be given to configurations where the sensing dots are incorporated in solid membranes and immobilized in optical fibers or planar waveguide platforms. PMID:28903308

Development of a Strontium Magneto-Optical Trap for Probing Casimir-Polder Potentials

NASA Astrophysics Data System (ADS)

Martin, Paul J.

In recent years, cold atoms have been the centerpiece of many remarkably sensitive measurements, and much effort has been made to devise miniaturized quantum sensors and quantum information processing devices. At small distances, however, mechanical effects of the quantum vacuum begin to significantly impact the behavior of the cold-atom systems. A better understanding of how surface composition and geometry affect Casimir and Casimir-Polder potentials would benefit future engineering of small-scale devices. Unfortunately, theoretical solutions are limited and the number of experimental techniques that can accurately detect such short-range forces is relatively small. We believe the exemplary properties of atomic strontium--which have enabled unprecedented frequency metrology in optical lattice clocks--make it an ideal candidate for probing slight spectroscopic perturbations caused by vacuum fluctuations. To that end, we have constructed a magneto-optical trap for strontium to enable future study of atom-surface potentials, and the apparatus and proposed detection scheme are discussed herein. Of special note is a passively stable external-cavity diode laser we developed that is both affordable and competitive with high-end commercial options.

Nonradiating and radiating modes excited by quantum emitters in open epsilon-near-zero cavities

PubMed Central

Liberal, Iñigo; Engheta, Nader

2016-01-01

Controlling the emission and interaction properties of quantum emitters (QEs) embedded within an optical cavity is a key technique in engineering light-matter interactions at the nanoscale, as well as in the development of quantum information processing. State-of-the-art optical cavities are based on high quality factor photonic crystals and dielectric resonators. However, wealthier responses might be attainable with cavities carved in more exotic materials. We theoretically investigate the emission and interaction properties of QEs embedded in open epsilon-near-zero (ENZ) cavities. Using analytical methods and numerical simulations, we demonstrate that open ENZ cavities present the unique property of supporting nonradiating modes independently of the geometry of the external boundary of the cavity (shape, size, topology, etc.). Moreover, the possibility of switching between radiating and nonradiating modes enables a dynamic control of the emission by, and the interaction between, QEs. These phenomena provide unprecedented degrees of freedom in controlling and trapping fields within optical cavities, as well as in the design of cavity opto- and acoustomechanical systems. PMID:27819047

Nonradiating and radiating modes excited by quantum emitters in open epsilon-near-zero cavities.

PubMed

Liberal, Iñigo; Engheta, Nader

2016-10-01

Controlling the emission and interaction properties of quantum emitters (QEs) embedded within an optical cavity is a key technique in engineering light-matter interactions at the nanoscale, as well as in the development of quantum information processing. State-of-the-art optical cavities are based on high quality factor photonic crystals and dielectric resonators. However, wealthier responses might be attainable with cavities carved in more exotic materials. We theoretically investigate the emission and interaction properties of QEs embedded in open epsilon-near-zero (ENZ) cavities. Using analytical methods and numerical simulations, we demonstrate that open ENZ cavities present the unique property of supporting nonradiating modes independently of the geometry of the external boundary of the cavity (shape, size, topology, etc.). Moreover, the possibility of switching between radiating and nonradiating modes enables a dynamic control of the emission by, and the interaction between, QEs. These phenomena provide unprecedented degrees of freedom in controlling and trapping fields within optical cavities, as well as in the design of cavity opto- and acoustomechanical systems.

Complete coherent control of silicon vacancies in diamond nanopillars containing single defect centers

DOE PAGES

Zhang, Jingyuan Linda; Lagoudakis, Konstantinos G.; Tzeng, Yan -Kai; ...

2017-10-23

Arrays of identical and individually addressable qubits lay the foundation for the creation of scalable quantum hardware such as quantum processors and repeaters. Silicon-vacancy (SiV) centers in diamond offer excellent physical properties such as low inhomogeneous broadening, fast photon emission, and a large Debye–Waller factor. The possibility for all-optical ultrafast manipulation and techniques to extend the spin coherence times makes them promising candidates for qubits. Here, we have developed arrays of nanopillars containing single (SiV) centers with high yield, and we demonstrate ultrafast all-optical complete coherent control of the excited state population of a single SiV center at the opticalmore » transition frequency. The high quality of the chemical vapor deposition (CVD) grown SiV centers provides excellent spectral stability, which allows us to coherently manipulate and quasi-resonantly read out the excited state population of individual SiV centers on picosecond timescales using ultrafast optical pulses. Furthermore, this work opens new opportunities to create a scalable on-chip diamond platform for quantum information processing and scalable nanophotonics applications.« less

Complete coherent control of silicon vacancies in diamond nanopillars containing single defect centers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jingyuan Linda; Lagoudakis, Konstantinos G.; Tzeng, Yan -Kai

Arrays of identical and individually addressable qubits lay the foundation for the creation of scalable quantum hardware such as quantum processors and repeaters. Silicon-vacancy (SiV) centers in diamond offer excellent physical properties such as low inhomogeneous broadening, fast photon emission, and a large Debye–Waller factor. The possibility for all-optical ultrafast manipulation and techniques to extend the spin coherence times makes them promising candidates for qubits. Here, we have developed arrays of nanopillars containing single (SiV) centers with high yield, and we demonstrate ultrafast all-optical complete coherent control of the excited state population of a single SiV center at the opticalmore » transition frequency. The high quality of the chemical vapor deposition (CVD) grown SiV centers provides excellent spectral stability, which allows us to coherently manipulate and quasi-resonantly read out the excited state population of individual SiV centers on picosecond timescales using ultrafast optical pulses. Furthermore, this work opens new opportunities to create a scalable on-chip diamond platform for quantum information processing and scalable nanophotonics applications.« less

Nanometric summation architecture based on optical near-field interaction between quantum dots.

PubMed

Naruse, Makoto; Miyazaki, Tetsuya; Kubota, Fumito; Kawazoe, Tadashi; Kobayashi, Kiyoshi; Sangu, Suguru; Ohtsu, Motoichi

2005-01-15

A nanoscale data summation architecture is proposed and experimentally demonstrated based on the optical near-field interaction between quantum dots. Based on local electromagnetic interactions between a few nanometric elements via optical near fields, we can combine multiple excitations at a certain quantum dot, which allows construction of a summation architecture. Summation plays a key role for content-addressable memory, which is one of the most important functions in optical networks.

Book Review:

NASA Astrophysics Data System (ADS)

Beenakker, C. W. J.

2005-08-01

Quantum Noise is advertised as a handbook, and this is indeed how it functions for me these days: it is a book that I keep within hand's reach, ready to be consulted on the proper use of quantum stochastic methods in the course of my research on quantum dots. I should point out that quantum optics, the target field for this book, is not my field by training. So I have much to learn, and find this handbook to be a reliable and helpful guide. Crispin Gardiner previously wrote the Handbook of Stochastic Methods (also published by Springer), which provides an overview of methods in classical statistical physics. Quantum Noise, written jointly with Peter Zoller, is the counterpart for quantum statistical physics, and indeed the two books rely on each other by frequent cross referencing. The fundamental problem addressed by Quantum Noise is how the quantum dynamics of an open system can be described statistically by treating the environment as a source of noise. This is a general problem in condensed matter physics (in particular in the context of Josephson junctions) and in quantum optics. The emphasis in this book in on the optical applications (for condensed matter applications one could consult Quantum Dissipative Systems by Ulrich Weiss, published by World Scientific). The optical applications centre around the interaction of light with atoms, where the atoms represent the open system and the light is the noisy environment. A complete description of the production and detection of non-classical states of radiation (such as squeezed states) can be obtained using one of the equivalent quantum stochastic formulations: the quantum Langevin equation for the field operators (in either the Ito or the Stratonovich form), the Master equation for the density matrix, or the stochastic Schrödinger equation for the wave functions. Each formulation is fully developed here (as one would expect from a handbook), with detailed instructions on how to go from one to the other. The development of the topic is precise and well-organized. The derivations are written out in sufficient detail, without frustrating comments like `it can be shown that'. The book is not quite self-contained, because it relies on the Handbook of Stochastic Methods for some background material (notably the issue of Ito versus Stratonovich). Still, one could very well use this book as a text for a course, supplying the background material to the students in some other form. Quantum Noise is now in its third edition. The second edition was a major expansion, including applications to laser cooling and quantum information processing. The third edition is a relatively minor upgrade, consisting mainly of pointers to recent literature. If you own the second edition, you might well skip this upgrade. If you do not yet own the book, or are still at edition 1, then I would enthusiastically recommend acquiring this handbook, regardless of whether you work in quantum optics or in another field of quantum physics. As I did, you might well find a new tool to attack your favourite problem.

Selective distillation phenomenon in two-species Bose-Einstein condensates in open boundary optical lattices.

PubMed

Bai, Xiao-Dong; Zhang, Mei; Xiong, Jun; Yang, Guo-Jian; Deng, Fu-Guo

2015-11-24

We investigate the formation of discrete breathers (DBs) and the dynamics of the mixture of two-species Bose-Einstein condensates (BECs) in open boundary optical lattices using the discrete nonlinear Schrödinger equations. The results show that the coupling of intra- and interspecies interaction can lead to the existence of pure single-species DBs and symbiotic DBs (i.e., two-species DBs). Furthermore, we find that there is a selective distillation phenomenon in the dynamics of the mixture of two-species BECs. One can selectively distil one species from the mixture of two-species BECs and can even control dominant species fraction by adjusting the intra- and interspecies interaction in optical lattices. Our selective distillation mechanism may find potential application in quantum information storage and quantum information processing based on multi-species atoms.

Selective distillation phenomenon in two-species Bose-Einstein condensates in open boundary optical lattices

PubMed Central

Bai, Xiao-Dong; Zhang, Mei; Xiong, Jun; Yang, Guo-Jian; Deng, Fu-Guo

2015-01-01

We investigate the formation of discrete breathers (DBs) and the dynamics of the mixture of two-species Bose-Einstein condensates (BECs) in open boundary optical lattices using the discrete nonlinear Schrödinger equations. The results show that the coupling of intra- and interspecies interaction can lead to the existence of pure single-species DBs and symbiotic DBs (i.e., two-species DBs). Furthermore, we find that there is a selective distillation phenomenon in the dynamics of the mixture of two-species BECs. One can selectively distil one species from the mixture of two-species BECs and can even control dominant species fraction by adjusting the intra- and interspecies interaction in optical lattices. Our selective distillation mechanism may find potential application in quantum information storage and quantum information processing based on multi-species atoms. PMID:26597592

Analysis of imperfections in the coherent optical excitation of single atoms to Rydberg states

NASA Astrophysics Data System (ADS)

de Léséleuc, Sylvain; Barredo, Daniel; Lienhard, Vincent; Browaeys, Antoine; Lahaye, Thierry

2018-05-01

We study experimentally various physical limitations and technical imperfections that lead to damping and finite contrast of optically driven Rabi oscillations between ground and Rydberg states of a single atom. Finite contrast is due to preparation and detection errors, and we show how to model and measure them accurately. Part of these errors originates from the finite lifetime of Rydberg states, and we observe its n3 scaling with the principal quantum number n . To explain the damping of Rabi oscillations, we use simple numerical models taking into account independently measured experimental imperfections and show that the observed damping actually results from the accumulation of several small effects, each at the level of a few percent. We discuss prospects for improving the coherence of ground-Rydberg Rabi oscillations in view of applications in quantum simulation and quantum information processing with arrays of single Rydberg atoms.

1.55 μm room-temperature lasing from subwavelength quantum-dot microdisks directly grown on (001) Si

NASA Astrophysics Data System (ADS)

Shi, Bei; Zhu, Si; Li, Qiang; Tang, Chak Wah; Wan, Yating; Hu, Evelyn L.; Lau, Kei May

2017-03-01

Miniaturized laser sources can benefit a wide variety of applications ranging from on-chip optical communications and data processing, to biological sensing. There is a tremendous interest in integrating these lasers with rapidly advancing silicon photonics, aiming to provide the combined strength of the optoelectronic integrated circuits and existing large-volume, low-cost silicon-based manufacturing foundries. Using III-V quantum dots as the active medium has been proven to lower power consumption and improve device temperature stability. Here, we demonstrate room-temperature InAs/InAlGaAs quantum-dot subwavelength microdisk lasers epitaxially grown on (001) Si, with a lasing wavelength of 1563 nm, an ultralow-threshold of 2.73 μW, and lasing up to 60 °C under pulsed optical pumping. This result unambiguously offers a promising path towards large-scale integration of cost-effective and energy-efficient silicon-based long-wavelength lasers.

Toward a compact fibered squeezing parametric source.

PubMed

Brieussel, Alexandre; Ott, Konstantin; Joos, Maxime; Treps, Nicolas; Fabre, Claude

2018-03-15

In this work, we investigate three different compact fibered systems generating vacuum squeezing that involve optical cavities limited by the end surface of a fiber and by a curved mirror and containing a thin parametric crystal. These systems have the advantage to couple squeezed states directly to a fiber, allowing the user to benefit from the flexibility of fibers in the use of squeezing. Three types of fibers are investigated: standard single-mode fibers, photonic-crystal large-mode-area single-mode fibers, and short multimode fibers taped to a single-mode fiber. The observed squeezing is modest (-0.56  dB, -0.9  dB, -1  dB), but these experiments open the way for miniaturized squeezing devices that could be a very interesting advantage in scaling up quantum systems for quantum processing, opening new perspectives in the domain of integrated quantum optics.

Hyperentanglement concentration for polarization-spatial-time-bin hyperentangled photon systems with linear optics

NASA Astrophysics Data System (ADS)

Wang, Hong; Ren, Bao-Cang; Alzahrani, Faris; Hobiny, Aatef; Deng, Fu-Guo

2017-10-01

Hyperentanglement has significant applications in quantum information processing. Here we present an efficient hyperentanglement concentration protocol (hyper-ECP) for partially hyperentangled Bell states simultaneously entangled in polarization, spatial-mode and time-bin degrees of freedom (DOFs) with the parameter-splitting method, where the parameters of the partially hyperentangled Bell states are known to the remote parties. In this hyper-ECP, only one remote party is required to perform some local operations on the three DOFs of a photon, only the linear optical elements are considered, and the success probability can achieve the maximal value. Our hyper-ECP can be easily generalized to concentrate the N-photon partially hyperentangled Greenberger-Horne-Zeilinger states with known parameters, where the multiple DOFs have largely improved the channel capacity of long-distance quantum communication. All of these make our hyper-ECP more practical and useful in high-capacity long-distance quantum communication.

InAs based terahertz quantum cascade lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandstetter, Martin, E-mail: martin.brandstetter@tuwien.ac.at; Kainz, Martin A.; Krall, Michael

2016-01-04

We demonstrate terahertz lasing emission from a quantum cascade structure, realized with InAs/AlAs{sub 0.16}Sb{sub 0.84} heterostructures. Due to the lower effective electron mass, InAs based active regions are expected to provide a higher optical gain compared to structures consisting of GaAs or InGaAs. The growth by molecular beam epitaxy enabled the fabrication of monolayer-thick barriers, required for the active region, which is based on a 3-well resonant phonon depletion design. Devices were processed in a double-metal waveguide geometry to ensure high mode confinement and low optical losses. Lasing emission at 3.8 THz was observed at liquid helium temperatures by applyingmore » a magnetic field perpendicular to the layered structure in order to suppress parasitic scattering channels. These results demonstrate the feasibility of InAs based active regions for terahertz quantum cascade lasers, potentially enabling higher operating temperatures.« less

Dynamic nuclear spin polarization in the resonant laser excitation of an InGaAs quantum dot.

PubMed

Högele, A; Kroner, M; Latta, C; Claassen, M; Carusotto, I; Bulutay, C; Imamoglu, A

2012-05-11

Resonant optical excitation of lowest-energy excitonic transitions in self-assembled quantum dots leads to nuclear spin polarization that is qualitatively different from the well-known optical orientation phenomena. By carrying out a comprehensive set of experiments, we demonstrate that nuclear spin polarization manifests itself in quantum dots subjected to finite external magnetic field as locking of the higher energy Zeeman transition to the driving laser field, as well as the avoidance of the resonance condition for the lower energy Zeeman branch. We interpret our findings on the basis of dynamic nuclear spin polarization originating from noncollinear hyperfine interaction and find excellent agreement between experiment and theory. Our results provide evidence for the significance of noncollinear hyperfine processes not only for nuclear spin diffusion and decay, but also for buildup dynamics of nuclear spin polarization in a coupled electron-nuclear spin system.

Two-photon interference of weak coherent laser pulses recalled from separate solid-state quantum memories

NASA Astrophysics Data System (ADS)

Jin, Jeongwan; Slater, Joshua A.; Saglamyurek, Erhan; Sinclair, Neil; George, Mathew; Ricken, Raimund; Oblak, Daniel; Sohler, Wolfgang; Tittel, Wolfgang

2013-08-01

Quantum memories allowing reversible transfer of quantum states between light and matter are central to quantum repeaters, quantum networks and linear optics quantum computing. Significant progress regarding the faithful transfer of quantum information has been reported in recent years. However, none of these demonstrations confirm that the re-emitted photons remain suitable for two-photon interference measurements, such as C-NOT gates and Bell-state measurements, which constitute another key ingredient for all aforementioned applications. Here, using pairs of laser pulses at the single-photon level, we demonstrate two-photon interference and Bell-state measurements after either none, one or both pulses have been reversibly mapped to separate thulium-doped lithium niobate waveguides. As the interference is always near the theoretical maximum, we conclude that our solid-state quantum memories, in addition to faithfully mapping quantum information, also preserve the entire photonic wavefunction. Hence, our memories are generally suitable for future applications of quantum information processing that require two-photon interference.

Two-photon interference of weak coherent laser pulses recalled from separate solid-state quantum memories.

PubMed

Jin, Jeongwan; Slater, Joshua A; Saglamyurek, Erhan; Sinclair, Neil; George, Mathew; Ricken, Raimund; Oblak, Daniel; Sohler, Wolfgang; Tittel, Wolfgang

2013-01-01

Quantum memories allowing reversible transfer of quantum states between light and matter are central to quantum repeaters, quantum networks and linear optics quantum computing. Significant progress regarding the faithful transfer of quantum information has been reported in recent years. However, none of these demonstrations confirm that the re-emitted photons remain suitable for two-photon interference measurements, such as C-NOT gates and Bell-state measurements, which constitute another key ingredient for all aforementioned applications. Here, using pairs of laser pulses at the single-photon level, we demonstrate two-photon interference and Bell-state measurements after either none, one or both pulses have been reversibly mapped to separate thulium-doped lithium niobate waveguides. As the interference is always near the theoretical maximum, we conclude that our solid-state quantum memories, in addition to faithfully mapping quantum information, also preserve the entire photonic wavefunction. Hence, our memories are generally suitable for future applications of quantum information processing that require two-photon interference.

Realization of a Cascaded Quantum System: Heralded Absorption of a Single Photon Qubit by a Single-Electron Charged Quantum Dot.

PubMed

Delteil, Aymeric; Sun, Zhe; Fält, Stefan; Imamoğlu, Atac

2017-04-28

Photonic losses pose a major limitation for the implementation of a quantum state transfer between nodes of a quantum network. A measurement that heralds a successful transfer without revealing any information about the qubit may alleviate this limitation. Here, we demonstrate the heralded absorption of a single photonic qubit, generated by a single neutral quantum dot, by a single-electron charged quantum dot that is located 5 m away. The transfer of quantum information to the spin degree of freedom takes place upon the emission of a photon; for a properly chosen or prepared quantum dot, the detection of this photon yields no information about the qubit. We show that this process can be combined with local operations optically performed on the destination node by measuring classical correlations between the absorbed photon color and the final state of the electron spin. Our work suggests alternative avenues for the realization of quantum information protocols based on cascaded quantum systems.

A variable partially polarizing beam splitter.

PubMed

Flórez, Jefferson; Carlson, Nathan J; Nacke, Codey H; Giner, Lambert; Lundeen, Jeff S

2018-02-01

We present designs for variably polarizing beam splitters. These are beam splitters allowing the complete and independent control of the horizontal and vertical polarization splitting ratios. They have quantum optics and quantum information applications, such as quantum logic gates for quantum computing and non-local measurements for quantum state estimation. At the heart of each design is an interferometer. We experimentally demonstrate one particular implementation, a displaced Sagnac interferometer configuration, that provides an inherent instability to air currents and vibrations. Furthermore, this design does not require any custom-made optics but only common components which can be easily found in an optics laboratory.

A variable partially polarizing beam splitter

NASA Astrophysics Data System (ADS)

Flórez, Jefferson; Carlson, Nathan J.; Nacke, Codey H.; Giner, Lambert; Lundeen, Jeff S.

2018-02-01

We present designs for variably polarizing beam splitters. These are beam splitters allowing the complete and independent control of the horizontal and vertical polarization splitting ratios. They have quantum optics and quantum information applications, such as quantum logic gates for quantum computing and non-local measurements for quantum state estimation. At the heart of each design is an interferometer. We experimentally demonstrate one particular implementation, a displaced Sagnac interferometer configuration, that provides an inherent instability to air currents and vibrations. Furthermore, this design does not require any custom-made optics but only common components which can be easily found in an optics laboratory.

Cavity Optomechanics at Millikelvin Temperatures

NASA Astrophysics Data System (ADS)

Meenehan, Sean Michael

The field of cavity optomechanics, which concerns the coupling of a mechanical object's motion to the electromagnetic field of a high finesse cavity, allows for exquisitely sensitive measurements of mechanical motion, from large-scale gravitational wave detection to microscale accelerometers. Moreover, it provides a potential means to control and engineer the state of a macroscopic mechanical object at the quantum level, provided one can realize sufficiently strong interaction strengths relative to the ambient thermal noise. Recent experiments utilizing the optomechanical interaction to cool mechanical resonators to their motional quantum ground state allow for a variety of quantum engineering applications, including preparation of non-classical mechanical states and coherent optical to microwave conversion. Optomechanical crystals (OMCs), in which bandgaps for both optical and mechanical waves can be introduced through patterning of a material, provide one particularly attractive means for realizing strong interactions between high-frequency mechanical resonators and near-infrared light. Beyond the usual paradigm of cavity optomechanics involving isolated single mechanical elements, OMCs can also be fashioned into planar circuits for photons and phonons, and arrays of optomechanical elements can be interconnected via optical and acoustic waveguides. Such coupled OMC arrays have been proposed as a way to realize quantum optomechanical memories, nanomechanical circuits for continuous variable quantum information processing and phononic quantum networks, and as a platform for engineering and studying quantum many-body physics of optomechanical meta-materials. However, while ground state occupancies (that is, average phonon occupancies less than one) have been achieved in OMC cavities utilizing laser cooling techniques, parasitic absorption and the concomitant degradation of the mechanical quality factor fundamentally limit this approach. On the other hand, the high mechanical frequency of these systems allows for the possibility of using a dilution refrigerator to simultaneously achieve low thermal occupancy and long mechanical coherence time by passively cooling the device to the millikelvin regime. This thesis describes efforts to realize the measurement of OMC cavities inside a dilution refrigerator, including the development of fridge-compatible optical coupling schemes and the characterization of the heating dynamics of the mechanical resonator at sub-kelvin temperatures. We will begin by summarizing the theoretical framework used to describe cavity optomechanical systems, as well as a handful of the quantum applications envisioned for such devices. Then, we will present background on the design of the nanobeam OMC cavities used for this work, along with details of the design and characterization of tapered fiber couplers for optical coupling inside the fridge. Finally, we will present measurements of the devices at fridge base temperatures of Tf = 10 mK, using both heterodyne spectroscopy and time-resolved sideband photon counting, as well as detailed analysis of the prospects for future quantum applications based on the observed optically-induced heating.

Feedback-induced bistability of an optically levitated nanoparticle: A Fokker-Planck treatment

NASA Astrophysics Data System (ADS)

Ge, Wenchao; Rodenburg, Brandon; Bhattacharya, M.

2016-08-01

Optically levitated nanoparticles have recently emerged as versatile platforms for investigating macroscopic quantum mechanics and enabling ultrasensitive metrology. In this paper we theoretically consider two damping regimes of an optically levitated nanoparticle cooled by cavityless parametric feedback. Our treatment is based on a generalized Fokker-Planck equation derived from the quantum master equation presented recently and shown to agree very well with experiment [B. Rodenburg, L. P. Neukirch, A. N. Vamivakas, and M. Bhattacharya, Quantum model of cooling and force sensing with an optically trapped nanoparticle, Optica 3, 318 (2016), 10.1364/OPTICA.3.000318]. For low damping, we find that the resulting Wigner function yields the single-peaked oscillator position distribution and recovers the appropriate energy distribution derived earlier using a classical theory and verified experimentally [J. Gieseler, R. Quidant, C. Dellago, and L. Novotny, Dynamic relaxation of a levitated nanoparticle from a non-equilibrium steady state, Nat. Nano. 9, 358 (2014), 10.1038/nnano.2014.40]. For high damping, in contrast, we predict a double-peaked position distribution, which we trace to an underlying bistability induced by feedback. Unlike in cavity-based optomechanics, stochastic processes play a major role in determining the bistable behavior. To support our conclusions, we present analytical expressions as well as numerical simulations using the truncated Wigner function approach. Our work opens up the prospect of developing bistability-based devices, characterization of phase-space dynamics, and investigation of the quantum-classical transition using levitated nanoparticles.

Theoretical model of dynamic spin polarization of nuclei coupled to paramagnetic point defects in diamond and silicon carbide

NASA Astrophysics Data System (ADS)

Ivády, Viktor; Szász, Krisztián; Falk, Abram L.; Klimov, Paul V.; Christle, David J.; Janzén, Erik; Abrikosov, Igor A.; Awschalom, David D.; Gali, Adam

2015-09-01

Dynamic nuclear spin polarization (DNP) mediated by paramagnetic point defects in semiconductors is a key resource for both initializing nuclear quantum memories and producing nuclear hyperpolarization. DNP is therefore an important process in the field of quantum-information processing, sensitivity-enhanced nuclear magnetic resonance, and nuclear-spin-based spintronics. DNP based on optical pumping of point defects has been demonstrated by using the electron spin of nitrogen-vacancy (NV) center in diamond, and more recently, by using divacancy and related defect spins in hexagonal silicon carbide (SiC). Here, we describe a general model for these optical DNP processes that allows the effects of many microscopic processes to be integrated. Applying this theory, we gain a deeper insight into dynamic nuclear spin polarization and the physics of diamond and SiC defects. Our results are in good agreement with experimental observations and provide a detailed and unified understanding. In particular, our findings show that the defect electron spin coherence times and excited state lifetimes are crucial factors in the entire DNP process.

LASER APPLICATIONS AND OTHER ASPECTS OF QUANTUM ELECTRONICS Measurement of angular parameters of divergent optical radiation by light diffraction on sound

NASA Astrophysics Data System (ADS)

Kotov, V. M.; Averin, S. V.; Shkerdin, G. N.

2010-12-01

A method is proposed to measure the scattering angle of optical radiation, the method employing two Bragg diffraction processes in which divergent optical radiation propagates close to the optical axis of a uniaxial crystal, while the acoustic wave — orthogonally to this axis. The method does not require additional angular tuning of the acousto-optic cell. We suggest using a mask to measure the light divergence that is larger than the angle of Bragg scattering. The method can be used to measure the size of the polished glass plate inhomogeneities.

Tunable room-temperature spin-selective optical Stark effect in solution-processed layered halide perovskites

PubMed Central

Giovanni, David; Chong, Wee Kiang; Dewi, Herlina Arianita; Thirumal, Krishnamoorthy; Neogi, Ishita; Ramesh, Ramamoorthy; Mhaisalkar, Subodh; Mathews, Nripan; Sum, Tze Chien

2016-01-01

Ultrafast spin manipulation for opto–spin logic applications requires material systems that have strong spin-selective light-matter interaction. Conventional inorganic semiconductor nanostructures [for example, epitaxial II to VI quantum dots and III to V multiple quantum wells (MQWs)] are considered forerunners but encounter challenges such as lattice matching and cryogenic cooling requirements. Two-dimensional halide perovskite semiconductors, combining intrinsic tunable MQW structures and large oscillator strengths with facile solution processability, can offer breakthroughs in this area. We demonstrate novel room-temperature, strong ultrafast spin-selective optical Stark effect in solution-processed (C6H4FC2H4NH3)2PbI4 perovskite thin films. Exciton spin states are selectively tuned by ~6.3 meV using circularly polarized optical pulses without any external photonic cavity (that is, corresponding to a Rabi energy of ~55 meV and equivalent to applying a 70 T magnetic field), which is much larger than any conventional system. The facile halide and organic replacement in these perovskites affords control of the dielectric confinement and thus presents a straightforward strategy for tuning light-matter coupling strength. PMID:27386583

Phase Recovery Acceleration of Quantum-Dot Semiconductor Optical Amplifiers by Optical Pumping to Quantum-Well Wetting Layer

NASA Astrophysics Data System (ADS)

Kim, Jungho

2013-11-01

We theoretically investigate the phase recovery acceleration of quantum-dot (QD) semiconductor optical amplifiers (SOAs) by means of the optical pump injection to the quantum-well (QW) wetting layer (WL). We compare the ultrafast gain and phase recovery responses of QD SOAs in either the electrical or the optical pumping scheme by numerically solving 1088 coupled rate equations. The ultrafast gain recovery responses on the order of sub-picosecond are nearly the same for the two pumping schemes. The ultrafast phase recovery is not significantly accelerated by increasing the electrical current density, but greatly improved by increasing the optical pumping power to the QW WL. Because the phase recovery time of QD SOAs with the optical pumping scheme can be reduced down to several picoseconds, the complete phase recovery can be achieved when consecutive pulse signals with a repetition rate of 100 GHz is injected.

A topological quantum optics interface

NASA Astrophysics Data System (ADS)

Barik, Sabyasachi; Karasahin, Aziz; Flower, Christopher; Cai, Tao; Miyake, Hirokazu; DeGottardi, Wade; Hafezi, Mohammad; Waks, Edo

2018-02-01

The application of topology in optics has led to a new paradigm in developing photonic devices with robust properties against disorder. Although considerable progress on topological phenomena has been achieved in the classical domain, the realization of strong light-matter coupling in the quantum domain remains unexplored. We demonstrate a strong interface between single quantum emitters and topological photonic states. Our approach creates robust counterpropagating edge states at the boundary of two distinct topological photonic crystals. We demonstrate the chiral emission of a quantum emitter into these modes and establish their robustness against sharp bends. This approach may enable the development of quantum optics devices with built-in protection, with potential applications in quantum simulation and sensing.

SU-E-T-191: First Principle Calculation of Quantum Yield in Photodynamic Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abolfath, R; Guo, F; Chen, Z

Purpose: We present a first-principle method to calculate the spin transfer efficiency in oxygen induced by any photon fields especially in MeV energy range. The optical pumping is mediated through photosensitizers, e.g., porphyrin and/or ensemble of quantum dots. Methods: Under normal conditions, oxygen molecules are in the relatively non-reactive triplet state. In the presence of certain photosensitizer compounds such as porphyrins, electromagnetic radiation of specific wavelengths can excite oxygen to highly reactive singlet state. With selective uptake of photosensitizers by certain malignant cells, photon irradiation of phosensitized tumors can lead to selective killing of cancer cells. This is the basismore » of photodynamic therapy (PDT). Despite several attempts, PDT has not been clinically successful except in limited superficial cancers. Many parameters such as photon energy, conjugation with quantum dots etc. can be potentially combined with PDT in order to extend the role of PDT in cancer management. The key quantity for this optimization is the spin transfer efficiency in oxygen by any photon field. The first principle calculation model presented here, is an attempt to fill this need. We employ stochastic density matrix description of the quantum jumps and the rate equation methods in quantum optics based on Markov/Poisson processes and calculate time evolution of the population of the optically pumped singlet oxygen. Results: The results demonstrate the feasibility of our model in showing the dependence of the optical yield in generating spin-singlet oxygen on the experimental conditions. The adjustable variables can be tuned to maximize the population of the singlet oxygen hence the efficacy of the photodynamic therapy. Conclusion: The present model can be employed to fit and analyze the experimental data and possibly to assist researchers in optimizing the experimental conditions in photodynamic therapy.« less

Quantum repeaters using continuous-variable teleportation

NASA Astrophysics Data System (ADS)

Dias, Josephine; Ralph, T. C.

2017-02-01

Quantum optical states are fragile and can become corrupted when passed through a lossy communication channel. Unlike for classical signals, optical amplifiers cannot be used to recover quantum signals. Quantum repeaters have been proposed as a way of reducing errors and hence increasing the range of quantum communications. Current protocols target specific discrete encodings, for example quantum bits encoded on the polarization of single photons. We introduce a more general approach that can reduce the effect of loss on any quantum optical encoding, including those based on continuous variables such as the field amplitudes. We show that in principle the protocol incurs a resource cost that scales polynomially with distance. We analyze the simplest implementation and find that while its range is limited it can still achieve useful improvements in the distance over which quantum entanglement of field amplitudes can be distributed.

Spin fine structure of optically excited quantum dot molecules

NASA Astrophysics Data System (ADS)

Scheibner, M.; Doty, M. F.; Ponomarev, I. V.; Bracker, A. S.; Stinaff, E. A.; Korenev, V. L.; Reinecke, T. L.; Gammon, D.

2007-06-01

The interaction between spins in coupled quantum dots is revealed in distinct fine structure patterns in the measured optical spectra of InAs/GaAs double quantum dot molecules containing zero, one, or two excess holes. The fine structure is explained well in terms of a uniquely molecular interplay of spin-exchange interactions, Pauli exclusion, and orbital tunneling. This knowledge is critical for converting quantum dot molecule tunneling into a means of optically coupling not just orbitals but also spins.

Quantum Dots Microstructured Optical Fiber for X-Ray Detection

NASA Technical Reports Server (NTRS)

DeHaven, Stan; Williams, Phillip; Burke, Eric

2015-01-01

Microstructured optical fibers containing quantum dots scintillation material comprised of zinc sulfide nanocrystals doped with magnesium sulfide are presented. These quantum dots are applied inside the microstructured optical fibers using capillary action. The x-ray photon counts of these fibers are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The results of the fiber light output and associated effects of an acrylate coating and the quantum dot application technique are discussed.

Constructions of secure entanglement channels assisted by quantum dots inside single-sided optical cavities

NASA Astrophysics Data System (ADS)

Heo, Jino; Kang, Min-Sung; Hong, Chang-Ho; Choi, Seong-Gon; Hong, Jong-Phil

2017-08-01

We propose quantum information processing schemes to generate and swap entangled states based on the interactions between flying photons and quantum dots (QDs) confined within optical cavities for quantum communication. To produce and distribute entangled states (Bell and Greenberger-Horne-Zeilinger [GHZ] states) between the photonic qubits of flying photons of consumers (Alice and Bob) and electron-spin qubits of a provider (trust center, or TC), the TC employs the interactions of the QD-cavity system, which is composed of a charged QD (negatively charged exciton) inside a single-sided cavity. Subsequently, the TC constructs an entanglement channel (Bell state and 4-qubit GHZ state) to link one consumer with another through entanglement swapping, which can be realized to exploit a probe photon with interactions of the QD-cavity systems and single-qubit measurements without Bell state measurement, for quantum communication between consumers. Consequently, the TC, which has quantum nodes (QD-cavity systems), can accomplish constructing the entanglement channel (authenticated channel) between two separated consumers from the distributions of entangled states and entanglement swapping. Furthermore, our schemes using QD-cavity systems, which are feasible with a certain probability of success and high fidelity, can be experimentally implemented with technology currently in use.

Photon pair generation with tailored frequency correlations in graded-index multimode fibers.

PubMed

Pourbeyram, Hamed; Mafi, Arash

2018-05-01

We study theoretically the generation of photon pairs with controlled spectral correlations via the four-wave mixing process in graded-index multimode optical fibers (GIMFs). We show that the quantum correlations of the generated photons in GIMFs can be preserved over a wide spectral range for a tunable pump source. Therefore, GIMFs can be utilized as quantum-state-preserving tunable sources of photons. In particular, we have shown that it is possible to generate factorable two-photon states, which allow for heralding of pure-state single photons without the need for narrowband spectral post filtering. We also elaborate on the possibility of simultaneously generating correlated and uncorrelated photon pairs in the same optical fiber.

Far-Field to Near-Field Coupling for Enhancing Light-Matter Interaction

NASA Astrophysics Data System (ADS)

Bonakdar, Alireza

This thesis reports on theoretical, modeling, and experimental research within the framework of a key scientific question, which is enhancing the coupling between diffraction-limited far-field and sub-wavelength quantum emitter/absorber. A typical optoelectronic device delivers an optical process such as light detection (e.g. photodetector) or light intensity modulation (e.g. electro-absorptive modulator). In conventional devices, optical process is in the form of far-field or guided wave modes. The main aim of this thesis is to show that converting these modes into near-field domain can enhance the performance of the optoelectronic device. Light in the form of far-field can be converted into near-field domain by the optical antenna. Among different optoelectronic devices, this thesis focuses mainly on integrating the optical antenna with infrared photodetectors. The available semiconductors have weak infrared absorption that reduces light detection efficiency. Integration of the optical antenna with infrared absorber (such as quantum wells in quantum well infrared photodetector (QWIP)) increases the infrared absorption. Particularly this integration is favorable as the optical antenna has low metallic loss in infrared region. The author of this thesis believes that optical antenna has unique properties in confining light on the scale of deep sub-wavelength, enhancing electric field intensity and delivering optical energy to semiconductor absorbers. These properties are reaching into practical applications only if overall optical performance is low loss, parameter free (independent of optical parameters such a polarization and angle of incident) and broadband. In this thesis, the integration of optical antenna with infrared photodetectors and thermophotovoltaic are researched and developed which satisfy the aforementioned criteria. In addition, several different optical antennas have been designed, fabricated and characterized in order to analyze and demonstrate the improvement of infrared absorption. In terms of design, novel optical antennas were simulated and proposed for a variety of infrared photodetectors such as a quantum well infrared photodetector, metal-insulator-metal detector, Schottky infrared photodetector, and two-photon absorption infrared detector. Antenna analyzes are not limited to light detection as a chapter of this thesis devoted on design and develop of a low power and ultrafast all-optical/optomechanical switchable antenna. The rest of the manuscript contains the novel lithography method in order to fabricate optical antennas with low cost and in cm-scale area. The method is based on the microsphere photolithography that expose photoresist underneath each microsphere with a focused intensive light -so called photonic nanojet. The developed lithography method takes advantage of microscopic range of optical path (micro-optics) in microsphere lenses that allows to push the exposure wavelength beyond deep UV region, where the refractive optics becomes impractical due to severe material absorption. The author believes that micro-optics lithography is an excellent candidate for large area and high throughput fabrication of sub-100-nm feature sizes in periodic array. In particular, this method facilitates the feasibility of metasurfaces and metamaterials, optical coating with efficient photon extraction/trapping, and highly sensitive bio-sensors in near IR and visible ranges of spectrum.

Electro-optic routing of photons from a single quantum dot in photonic integrated circuits

NASA Astrophysics Data System (ADS)

Midolo, Leonardo; Hansen, Sofie L.; Zhang, Weili; Papon, Camille; Schott, Rüdiger; Ludwig, Arne; Wieck, Andreas D.; Lodahl, Peter; Stobbe, Søren

2017-12-01

Recent breakthroughs in solid-state photonic quantum technologies enable generating and detecting single photons with near-unity efficiency as required for a range of photonic quantum technologies. The lack of methods to simultaneously generate and control photons within the same chip, however, has formed a main obstacle to achieving efficient multi-qubit gates and to harness the advantages of chip-scale quantum photonics. Here we propose and demonstrate an integrated voltage-controlled phase shifter based on the electro-optic effect in suspended photonic waveguides with embedded quantum emitters. The phase control allows building a compact Mach-Zehnder interferometer with two orthogonal arms, taking advantage of the anisotropic electro-optic response in gallium arsenide. Photons emitted by single self-assembled quantum dots can be actively routed into the two outputs of the interferometer. These results, together with the observed sub-microsecond response time, constitute a significant step towards chip-scale single-photon-source de-multiplexing, fiber-loop boson sampling, and linear optical quantum computing.