Quantum Noise in Large-Scale Coherent Nonlinear Photonic Circuits
NASA Astrophysics Data System (ADS)
Santori, Charles; Pelc, Jason S.; Beausoleil, Raymond G.; Tezak, Nikolas; Hamerly, Ryan; Mabuchi, Hideo
2014-06-01
A semiclassical simulation approach is presented for studying quantum noise in large-scale photonic circuits incorporating an ideal Kerr nonlinearity. A circuit solver is used to generate matrices defining a set of stochastic differential equations, in which the resonator field variables represent random samplings of the Wigner quasiprobability distributions. Although the semiclassical approach involves making a large-photon-number approximation, tests on one- and two-resonator circuits indicate satisfactory agreement between the semiclassical and full-quantum simulation results in the parameter regime of interest. The semiclassical model is used to simulate random errors in a large-scale circuit that contains 88 resonators and hundreds of components in total and functions as a four-bit ripple counter. The error rate as a function of on-state photon number is examined, and it is observed that the quantum fluctuation amplitudes do not increase as signals propagate through the circuit, an important property for scalability.
Operating quantum waveguide circuits with superconducting single-photon detectors
NASA Astrophysics Data System (ADS)
Natarajan, C. M.; Peruzzo, A.; Miki, S.; Sasaki, M.; Wang, Z.; Baek, B.; Nam, S.; Hadfield, R. H.; O'Brien, J. L.
2010-05-01
Advanced quantum information science and technology (QIST) applications place exacting demands on optical components. Quantum waveguide circuits offer a route to scalable QIST on a chip. Superconducting single-photon detectors (SSPDs) provide infrared single-photon sensitivity combined with low dark counts and picosecond timing resolution. In this study, we bring these two technologies together. Using SSPDs we observe a two-photon interference visibility of 92.3±1.0% in a silica-on-silicon waveguide directional coupler at λ =804 nm—higher than that measured with silicon detectors (89.9±0.3%). We further operated controlled-NOT gate and quantum metrology circuits with SSPDs. These demonstrations present a clear path to telecom-wavelength quantum waveguide circuits.
Photonic Circuits with Time Delays and Quantum Feedback.
Pichler, Hannes; Zoller, Peter
2016-03-01
We study the dynamics of photonic quantum circuits consisting of nodes coupled by quantum channels. We are interested in the regime where the time delay in communication between the nodes is significant. This includes the problem of quantum feedback, where a quantum signal is fed back on a system with a time delay. We develop a matrix product state approach to solve the quantum stochastic Schrödinger equation with time delays, which accounts in an efficient way for the entanglement of nodes with the stream of emitted photons in the waveguide, and thus the non-Markovian character of the dynamics. We illustrate this approach with two paradigmatic quantum optical examples: two coherently driven distant atoms coupled to a photonic waveguide with a time delay, and a driven atom coupled to its own output field with a time delay as an instance of a quantum feedback problem. PMID:26991174
Photonic Circuits with Time Delays and Quantum Feedback
NASA Astrophysics Data System (ADS)
Pichler, Hannes; Zoller, Peter
2016-03-01
We study the dynamics of photonic quantum circuits consisting of nodes coupled by quantum channels. We are interested in the regime where the time delay in communication between the nodes is significant. This includes the problem of quantum feedback, where a quantum signal is fed back on a system with a time delay. We develop a matrix product state approach to solve the quantum stochastic Schrödinger equation with time delays, which accounts in an efficient way for the entanglement of nodes with the stream of emitted photons in the waveguide, and thus the non-Markovian character of the dynamics. We illustrate this approach with two paradigmatic quantum optical examples: two coherently driven distant atoms coupled to a photonic waveguide with a time delay, and a driven atom coupled to its own output field with a time delay as an instance of a quantum feedback problem.
Specification of photonic circuits using quantum hardware description language
Tezak, Nikolas; Niederberger, Armand; Pavlichin, Dmitri S.; Sarma, Gopal; Mabuchi, Hideo
2012-01-01
Following the simple observation that the interconnection of a set of quantum optical input–output devices can be specified using structural mode VHSIC hardware description language, we demonstrate a computer-aided schematic capture workflow for modelling and simulating multi-component photonic circuits. We describe an algorithm for parsing circuit descriptions to derive quantum equations of motion, illustrate our approach using simple examples based on linear and cavity-nonlinear optical components, and demonstrate a computational approach to hierarchical model reduction. PMID:23091208
Specification of photonic circuits using quantum hardware description language.
Tezak, Nikolas; Niederberger, Armand; Pavlichin, Dmitri S; Sarma, Gopal; Mabuchi, Hideo
2012-11-28
Following the simple observation that the interconnection of a set of quantum optical input-output devices can be specified using structural mode VHSIC hardware description language, we demonstrate a computer-aided schematic capture workflow for modelling and simulating multi-component photonic circuits. We describe an algorithm for parsing circuit descriptions to derive quantum equations of motion, illustrate our approach using simple examples based on linear and cavity-nonlinear optical components, and demonstrate a computational approach to hierarchical model reduction. PMID:23091208
Quantum interference in heterogeneous superconducting-photonic circuits on a silicon chip
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
Quantum interference in heterogeneous superconducting-photonic circuits on a silicon chip
NASA Astrophysics Data System (ADS)
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.
Quantum interference in heterogeneous superconducting-photonic circuits on a silicon chip.
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
Quantum nondemolition photon detection in circuit QED and the quantum Zeno effect
Helmer, Ferdinand; Marquardt, Florian; Mariantoni, Matteo; Solano, Enrique
2009-05-15
We analyze the detection of itinerant photons using a quantum nondemolition measurement. An important example is the dispersive detection of microwave photons in circuit quantum electrodynamics, which can be realized via the nonlinear interaction between photons inside a superconducting transmission line resonator. We show that the back action due to the continuous measurement imposes a limit on the detector efficiency in such a scheme. We illustrate this using a setup where signal photons have to enter a cavity in order to be detected dispersively. In this approach, the measurement signal is the phase shift imparted to an intense beam passing through a second cavity mode. The restrictions on the fidelity are a consequence of the quantum Zeno effect, and we discuss both analytical results and quantum trajectory simulations of the measurement process.
NASA Astrophysics Data System (ADS)
Heilmann, R.; Keil, R.; Gräfe, M.; Nolte, S.; Szameit, A.
2014-08-01
We present an innovative approach for ultra-precise phase manipulation in integrated photonic quantum circuits. To this end, we employ generalized directional couplers that utilize a detuning of the propagation constant in optical waveguides by the overlap of adjacent waveguide modes. We demonstrate our findings in experiments with classical as well as quantum light.
NASA Astrophysics Data System (ADS)
Barz, Stefanie
2015-04-01
Quantum physics has revolutionized our understanding of information processing and enables computational speed-ups that are unattainable using classical computers. This tutorial reviews the fundamental tools of photonic quantum information processing. The basics of theoretical quantum computing are presented and the quantum circuit model as well as measurement-based models of quantum computing are introduced. Furthermore, it is shown how these concepts can be implemented experimentally using photonic qubits, where information is encoded in the photons’ polarization.
Recursive multiport schemes for implementing quantum algorithms with photonic integrated circuits
NASA Astrophysics Data System (ADS)
Tabia, Gelo Noel M.
2016-01-01
We present recursive multiport schemes for implementing quantum Fourier transforms and the inversion step in Grover's algorithm on an integrated linear optics device. In particular, each scheme shows how to execute a quantum operation on 2 d modes using a pair of circuits for the same operation on d modes. The circuits operate on path-encoded qudits and realize d -dimensional unitary transformations on these states using linear optical networks with O (d2) optical elements. To evaluate the schemes against realistic errors, we ran simulations of proof-of-principle experiments using a simple fabrication model of silicon-based photonic integrated devices that employ directional couplers and thermo-optic modulators for beam splitters and phase shifters, respectively. We find that high-fidelity performance is achievable with our multiport circuits for 2-qubit and 3-qubit quantum Fourier transforms, and for quantum search on four-item and eight-item databases.
High-fidelity quantum state evolution in imperfect photonic integrated circuits
NASA Astrophysics Data System (ADS)
Mower, Jacob; Harris, Nicholas C.; Steinbrecher, Gregory R.; Lahini, Yoav; Englund, Dirk
2015-09-01
We propose and analyze the design of a programmable photonic integrated circuit for high-fidelity quantum computation and simulation. We demonstrate that the reconfigurability of our design allows us to overcome two major impediments to quantum optics on a chip: it removes the need for a full fabrication cycle for each experiment and allows for compensation of fabrication errors using numerical optimization techniques. Under a pessimistic fabrication model for the silicon-on-insulator process, we demonstrate a dramatic fidelity improvement for the linear optics controlled-not and controlled-phase gates and, showing the scalability of this approach, the iterative phase estimation algorithm built from individually optimized gates. We also propose and simulate an experiment that the programmability of our system would enable: a statistically robust study of the evolution of entangled photons in disordered quantum walks. Overall, our results suggest that existing fabrication processes are sufficient to build a quantum photonic processor capable of high-fidelity operation.
NASA Astrophysics Data System (ADS)
Englund, Dirk R.
2015-09-01
A central goal of quantum information science is the entanglement of multiple quantum memories that can be individually controlled. Here, we discuss progress towards photonic integrated circuits designed to enable efficient optical interactions between multiple spin qubits in nitrogen vacancy (NV) centers in diamond. We describe NV-nanocavity systems in the strong Purcell regime with optical quality factors approaching 10,000 and electron spin coherence times exceeding 200 μs implantation of NVs with nanometer-scale apertures, including into cavity field maxima; hybrid on-chip networks for integration of multiple functional NV-cavity systems; and scalable integration of superconducting nanowire single photon detectors on-chip.
Nano-photonics in III-V semiconductors for integrated quantum optical circuits
NASA Astrophysics Data System (ADS)
Wasley, Nicholas Andrew
This thesis describes the optical spectroscopic measurements of III-V semiconductors used to investigate a number of issues related to the development of integrated quantum optical circuits. The disorder-limited propagation of photons in photonic crystal waveguides in the slow-light regime is investigated. The analysis of Fabry-Perot resonances is used to map the mode dispersion and extract the photon localisation length. Andersonlocalised modes are observed at high group indices, when the localisation lengths are shorter than the waveguide lengths, consistent with the Fabry-Perot analysis. A spin-photon interface based on two orthogonal waveguides is introduced, where the polarisation emitted by a quantum dot is mapped to a path-encoded photon. Operation is demonstrated by deducing the spin using the interference of in-plane photons. A second device directly maps right and left circular polarisations to anti-parallel waveguides, surprising for a non-chiral structure but consistent with an off-centre dot. Two dimensional photonic crystal cavities in GaInP and full control over the spontaneous emission rate of InP quantum dots is demonstrated by spectrally tuning the exciton emission energy into resonance with the fundamental cavity mode. Fourier transform spectroscopy is used to investigate the short coherence times of InP quantum dots in GaInP photonic crystal cavities. Additional technological developments are also presented including a quantum dot registration technique, electrical tuning of quantum dot emission and uniaxial strain tuning of H1 cavity modes.
An optimized photon pair source for quantum circuits.
Harder, Georg; Ansari, Vahid; Brecht, Benjamin; Dirmeier, Thomas; Marquardt, Christoph; Silberhorn, Christine
2013-06-17
We implement an ultrafast pulsed type-II parametric down conversion source in a periodically poled KTP waveguide at telecommunication wavelengths with almost identical properties between signal and idler. As such, our source resembles closely a pure, genuine single mode photon pair source with indistinguishable modes. We measure the joint spectral intensity distribution and second order correlation functions of the marginal beams and find with both methods very low effective mode numbers corresponding to a Schmidt number below 1.16. We further demonstrate the indistinguishability as well as the purity of signal and idler photons by Hong-Ou-Mandel interferences between signal and idler and between signal/idler and a coherent field, respectively. Without using narrowband spectral filtering, we achieve a visibility for the interference between signal and idler of 94.8% and determine a purity of more than 80% for the heralded single photon states. Moreover, we measure raw heralding efficiencies of 20.5% and 15.5% for the signal and idler beams corresponding to detector-loss corrected values of 80% and 70%. PMID:23787587
NASA Astrophysics Data System (ADS)
Liu, YiMin; Jin, WuYin; You, JiaBin
2014-11-01
A hybrid quantum architecture was proposed to engineer a localization-delocalization phase transition of light in a two-dimension square lattices of superconducting coplanar waveguide resonators, which are interconnected by current-biased Josephson junction phase qubits. We find that the competition between the on-site repulsion and the nonlocal photonic hopping leads to the Mott insulator-superfluid transition. By using the mean-field approach and the quantum master equation, the phase boundary between these two different phases could be obtained when the dissipative effects of superconducting resonators and phase qubit are considered. The good tunability of the effective on-site repulsion and photon-hopping strengths enable quantum simulation on condensed matter physics and many-body models using such a superconducting resonator lattice system. The experimental feasibility is discussed using the currently available technology in the circuit QED.
The Photon Shell Game and the Quantum von Neumann Architecture with Superconducting Circuits
NASA Astrophysics Data System (ADS)
Mariantoni, Matteo
2012-02-01
Superconducting quantum circuits have made significant advances over the past decade, allowing more complex and integrated circuits that perform with good fidelity. We have recently implemented a machine comprising seven quantum channels, with three superconducting resonators, two phase qubits, and two zeroing registers. I will explain the design and operation of this machine, first showing how a single microwave photon | 1 > can be prepared in one resonator and coherently transferred between the three resonators. I will also show how more exotic states such as double photon states | 2 > and superposition states | 0 >+ | 1 > can be shuffled among the resonators as well [1]. I will then demonstrate how this machine can be used as the quantum-mechanical analog of the von Neumann computer architecture, which for a classical computer comprises a central processing unit and a memory holding both instructions and data. The quantum version comprises a quantum central processing unit (quCPU) that exchanges data with a quantum random-access memory (quRAM) integrated on one chip, with instructions stored on a classical computer. I will also present a proof-of-concept demonstration of a code that involves all seven quantum elements: (1), Preparing an entangled state in the quCPU, (2), writing it to the quRAM, (3), preparing a second state in the quCPU, (4), zeroing it, and, (5), reading out the first state stored in the quRAM [2]. Finally, I will demonstrate that the quantum von Neumann machine provides one unit cell of a two-dimensional qubit-resonator array that can be used for surface code quantum computing. This will allow the realization of a scalable, fault-tolerant quantum processor with the most forgiving error rates to date. [4pt] [1] M. Mariantoni et al., Nature Physics 7, 287-293 (2011.)[0pt] [2] M. Mariantoni et al., Science 334, 61-65 (2011).
Quantum dash based single section mode locked lasers for photonic integrated circuits.
Joshi, Siddharth; Calò, Cosimo; Chimot, Nicolas; Radziunas, Mindaugas; Arkhipov, Rostislav; Barbet, Sophie; Accard, Alain; Ramdane, Abderrahim; Lelarge, Francois
2014-05-01
We present the first demonstration of an InAs/InP Quantum Dash based single-section frequency comb generator designed for use in photonic integrated circuits (PICs). The laser cavity is closed using a specifically designed Bragg reflector without compromising the mode-locking performance of the self pulsating laser. This enables the integration of single-section mode-locked laser in photonic integrated circuits as on-chip frequency comb generators. We also investigate the relations between cavity modes in such a device and demonstrate how the dispersion of the complex mode frequencies induced by the Bragg grating implies a violation of the equi-distance between the adjacent mode frequencies and, therefore, forbids the locking of the modes in a classical Bragg Device. Finally we integrate such a Bragg Mirror based laser with Semiconductor Optical Amplifier (SOA) to demonstrate the monolithic integration of QDash based low phase noise sources in PICs. PMID:24921823
Fast universal quantum gates on microwave photons with all-resonance operations in circuit QED.
Hua, Ming; Tao, Ming-Jie; Deng, Fu-Guo
2015-01-01
Stark shift on a superconducting qubit in circuit quantum electrodynamics (QED) has been used to construct universal quantum entangling gates on superconducting resonators in previous works. It is a second-order coupling effect between the resonator and the qubit in the dispersive regime, which leads to a slow state-selective rotation on the qubit. Here, we present two proposals to construct the fast universal quantum gates on superconducting resonators in a microwave-photon quantum processor composed of multiple superconducting resonators coupled to a superconducting transmon qutrit, that is, the controlled-phase (c-phase) gate on two microwave-photon resonators and the controlled-controlled phase (cc-phase) gates on three resonators, resorting to quantum resonance operations, without any drive field. Compared with previous works, our universal quantum gates have the higher fidelities and shorter operation times in theory. The numerical simulation shows that the fidelity of our c-phase gate is 99.57% within about 38.1 ns and that of our cc-phase gate is 99.25% within about 73.3 ns. PMID:25787147
Realizing and characterizing chiral photon flow in a circuit quantum electrodynamics necklace
NASA Astrophysics Data System (ADS)
Wang, Yan-Pu; Wang, Wei; Xue, Zheng-Yuan; Yang, Wan-Li; Hu, Yong; Wu, Ying
2015-02-01
Gauge theory plays the central role in modern physics. Here we propose a scheme of implementing artificial Abelian gauge fields via the parametric conversion method in a necklace of superconducting transmission line resonators (TLRs) coupled by superconducting quantum interference devices (SQUIDs). The motivation is to synthesize an extremely strong effective magnetic field for charge-neutral bosons which can hardly be achieved in conventional solid-state systems. The dynamic modulations of the SQUIDs can induce effective magnetic fields for the microwave photons in the TLR necklace through the generation of the nontrivial hopping phases of the photon hopping between neighboring TLRs. To demonstrate the synthetic magnetic field, we study the realization and detection of the chiral photon flow dynamics in this architecture under the influence of decoherence. Taking the advantages of its simplicity and flexibility, this parametric scheme is feasible with state-of-the-art technology and may pave an alternative way for investigating the gauge theories with superconducting quantum circuits. We further propose a quantitative measure for the chiral property of the photon flow. Beyond the level of qualitative description, the dependence of the chiral flow on external pumping parameters and cavity decay is characterized.
Realizing and characterizing chiral photon flow in a circuit quantum electrodynamics necklace
Wang, Yan-Pu; Wang, Wei; Xue, Zheng-Yuan; Yang, Wan-Li; Hu, Yong; Wu, Ying
2015-01-01
Gauge theory plays the central role in modern physics. Here we propose a scheme of implementing artificial Abelian gauge fields via the parametric conversion method in a necklace of superconducting transmission line resonators (TLRs) coupled by superconducting quantum interference devices (SQUIDs). The motivation is to synthesize an extremely strong effective magnetic field for charge-neutral bosons which can hardly be achieved in conventional solid-state systems. The dynamic modulations of the SQUIDs can induce effective magnetic fields for the microwave photons in the TLR necklace through the generation of the nontrivial hopping phases of the photon hopping between neighboring TLRs. To demonstrate the synthetic magnetic field, we study the realization and detection of the chiral photon flow dynamics in this architecture under the influence of decoherence. Taking the advantages of its simplicity and flexibility, this parametric scheme is feasible with state-of-the-art technology and may pave an alternative way for investigating the gauge theories with superconducting quantum circuits. We further propose a quantitative measure for the chiral property of the photon flow. Beyond the level of qualitative description, the dependence of the chiral flow on external pumping parameters and cavity decay is characterized. PMID:25666884
Realizing and characterizing chiral photon flow in a circuit quantum electrodynamics necklace.
Wang, Yan-Pu; Wang, Wei; Xue, Zheng-Yuan; Yang, Wan-Li; Hu, Yong; Wu, Ying
2015-01-01
Gauge theory plays the central role in modern physics. Here we propose a scheme of implementing artificial Abelian gauge fields via the parametric conversion method in a necklace of superconducting transmission line resonators (TLRs) coupled by superconducting quantum interference devices (SQUIDs). The motivation is to synthesize an extremely strong effective magnetic field for charge-neutral bosons which can hardly be achieved in conventional solid-state systems. The dynamic modulations of the SQUIDs can induce effective magnetic fields for the microwave photons in the TLR necklace through the generation of the nontrivial hopping phases of the photon hopping between neighboring TLRs. To demonstrate the synthetic magnetic field, we study the realization and detection of the chiral photon flow dynamics in this architecture under the influence of decoherence. Taking the advantages of its simplicity and flexibility, this parametric scheme is feasible with state-of-the-art technology and may pave an alternative way for investigating the gauge theories with superconducting quantum circuits. We further propose a quantitative measure for the chiral property of the photon flow. Beyond the level of qualitative description, the dependence of the chiral flow on external pumping parameters and cavity decay is characterized. PMID:25666884
NASA Astrophysics Data System (ADS)
Oda, H.; Yamanaka, A.; Ozaki, N.; Ikeda, N.; Sugimoto, Y.
2016-06-01
The development of small sized laser operating above room temperature is important in the realization of optical integrated circuits. Recently, micro-lasers consisting of photonic crystals (PhCs) and whispering gallery mode cavities have been demonstrated. Optically pumped laser devices could be easily designed using photonic crystal-slab waveguides (PhC-WGs) with an air-bridge type structure. In this study, we observe lasing at 1.3μm from two-photon pumped InAs-quantum-dots embedded GaAs PhC-WGs above room temperature. This type of compact laser shows promise as a new light source in ultra-compact photonics integrated circuits.
Design and characterization of integrated components for SiN photonic quantum circuits.
Poot, Menno; Schuck, Carsten; Ma, Xiao-Song; Guo, Xiang; Tang, Hong X
2016-04-01
The design, fabrication, and detailed calibration of essential building blocks towards fully integrated linear-optics quantum computation are discussed. Photonic devices are made from silicon nitride rib waveguides, where measurements on ring resonators show small propagation losses. Directional couplers are designed to be insensitive to fabrication variations. Their offset and coupling lengths are measured, as well as the phase difference between the transmitted and reflected light. With careful calibrations, the insertion loss of the directional couplers is found to be small. Finally, an integrated controlled-NOT circuit is characterized by measuring the transmission through different combinations of inputs and outputs. The gate fidelity for the CNOT operation with this circuit is estimated to be 99.81% after post selection. This high fidelity is due to our robust design, good fabrication reproducibility, and extensive characterizations. PMID:27136982
Design and characterization of integrated components for SiN photonic quantum circuits
NASA Astrophysics Data System (ADS)
Poot, Menno; Schuck, Carsten; Ma, Xiao-song; Guo, Xiang; Tang, Hong X.
2016-04-01
The design, fabrication, and detailed calibration of essential building blocks towards fully integrated linear-optics quantum computation are discussed. Photonic devices are made from silicon nitride rib waveguides, where measurements on ring resonators show small propagation losses. Directional couplers are designed to be insensitive to fabrication variations. Their offset and coupling lengths are measured, as well as the phase difference between the transmitted and reflected light. With careful calibrations, the insertion loss of the directional couplers is found to be small. Finally, an integrated controlled-NOT circuit is characterized by measuring the transmission through different combinations of inputs and outputs. The gate fidelity for the CNOT operation with this circuit is estimated to be 99.81% after post selection. This high fidelity is due to our robust design, good fabrication reproducibility, and extensive characterizations.
NASA Astrophysics Data System (ADS)
O'Brien, Jeremy
2013-03-01
Of the approaches to quantum computing, photons are appealing for their low-noise properties and ease of manipulation, and relevance to other quantum technologies, including communication, metrology and measurement. We report an integrated waveguide approach to photonic quantum circuits for high performance, miniaturization and scalability [6-10]. We address the challenges of scaling up quantum circuits using new insights into how controlled operations can be efficiently realised, demonstrating Shor's algorithm with consecutive CNOT gates and the iterative phase estimation algorithm. We have shown how quantum circuits can be reconfigured, using thermo-optic phase shifters to realise a highly reconfigurable quantum circuit, and electro-optic phase shifters in lithium niobate to rapidly manipulate the path and polarisation of telecomm wavelength single photons. We have addressed miniaturisation using multimode interference architectures to directly implement NxN Hadamard operations, and by using high refractive index contrast materials such as SiOxNy, in which we have implemented quantum walks of correlated photons, and Si, in which we have demonstrated generation of orbital angular momentum states of light. We have incorporated microfluidic channels for the delivery of samples to measure the concentration of a blood protein with entangled states of light. We have begun to address the integration of superconducting single photon detectors and diamond and non-linear single photon sources. Finally, we give an overview of recent work on fundamental aspects of quantum measurement, including a quantum version of Wheeler's delayed choice experiment.
NASA Astrophysics Data System (ADS)
Hwang, Myung-Joong; Kim, M. S.; Choi, Mahn-Soo
2016-04-01
We explore the photon population dynamics in two coupled circuit QED systems. For a sufficiently weak intercavity photon hopping, as the photon-cavity coupling increases, the dynamics undergoes double transitions first from a delocalized to a localized phase and then from the localized to another delocalized phase. The latter delocalized phase is distinguished from the former one; instead of oscillating between the two cavities, the photons rapidly quasiequilibrate over the two cavities. These intriguing features are attributed to an interplay between two qualitatively distinctive nonlinear behaviors of the circuit QED systems in the utrastrong coupling regime, whose distinction has been widely overlooked.
Hwang, Myung-Joong; Kim, M S; Choi, Mahn-Soo
2016-04-15
We explore the photon population dynamics in two coupled circuit QED systems. For a sufficiently weak intercavity photon hopping, as the photon-cavity coupling increases, the dynamics undergoes double transitions first from a delocalized to a localized phase and then from the localized to another delocalized phase. The latter delocalized phase is distinguished from the former one; instead of oscillating between the two cavities, the photons rapidly quasiequilibrate over the two cavities. These intriguing features are attributed to an interplay between two qualitatively distinctive nonlinear behaviors of the circuit QED systems in the utrastrong coupling regime, whose distinction has been widely overlooked. PMID:27127967
Quantum Optics with Superconducting Circuits: From Single Photons to Schrodinger Cats
Schoelkopf, Rob
2013-01-09
Over the last decade and a half, superconducting circuits have advanced to the point where we can generate and detect highly-entangled states, and perform universal quantum gates. Meanwhile, the coherence properties of these systems have improved more than 10,000-fold. I will describe recent experiments, such as the latest advance in coherence using a three-dimensional implementation of qubits interacting with microwave cavities, called “3D circuit QED.” The control and strong interactions possible in superconducting circuits make it possible to generate non-classical states of light, including large superpositions known as “Schrodinger cat” states. This field has many interesting prospects both for applications in quantum information processing, and fundamental investigations of the boundary between the macroscopic classical world and the microscopic world of the quantum.
Driven superconducting quantum circuits
NASA Astrophysics Data System (ADS)
Nakamura, Yasunobu
2014-03-01
Driven nonlinear quantum systems show rich phenomena in various fields of physics. Among them, superconducting quantum circuits have very attractive features such as well-controlled quantum states with design flexibility, strong nonlinearity of Josephson junctions, strong coupling to electromagnetic driving fields, little internal dissipation, and tailored coupling to the electromagnetic environment. We have investigated properties and functionalities of driven superconducting quantum circuits. A transmon qubit coupled to a transmission line shows nearly perfect spatial mode matching between the incident and scattered microwave field in the 1D mode. Dressed states under a driving field are studied there and also in a semi-infinite 1D mode terminated by a resonator containing a flux qubit. An effective Λ-type three-level system is realized under an appropriate driving condition. It allows ``impedance-matched'' perfect absorption of incident probe photons and down conversion into another frequency mode. Finally, the weak signal from the qubit is read out using a Josephson parametric amplifier/oscillator which is another nonlinear circuit driven by a strong pump field. This work was partly supported by the Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST), Project for Developing Innovation Systems of MEXT, MEXT KAKENHI ``Quantum Cybernetics,'' and the NICT Commissioned Research.
NASA Technical Reports Server (NTRS)
Merritt, Scott; Krainak, Michael
2016-01-01
Integrated photonics generally is the integration of multiple lithographically defined photonic and electronic components and devices (e.g. lasers, detectors, waveguides passive structures, modulators, electronic control and optical interconnects) on a single platform with nanometer-scale feature sizes. The development of photonic integrated circuits permits size, weight, power and cost reductions for spacecraft microprocessors, optical communication, processor buses, advanced data processing, and integrated optic science instrument optical systems, subsystems and components. This is particularly critical for small spacecraft platforms. We will give an overview of some NASA applications for integrated photonics.
Decoherence-protected spin-photon quantum gates in a hybrid semiconductor-superconductor circuit
NASA Astrophysics Data System (ADS)
Wang, Li; Tu, Tao; Gong, Bo; Guo, Guang-Can
2015-12-01
High-fidelity gate operations are a crucial function for quantum information processing. This problem is particularly challenging for hybrid systems where coherence and control time scales greatly differ by orders of magnitude among different elements. Here we propose decoherence-protected gate operations in an important class of hybrid system in the context of a spin qubit in semiconductor quantum dots coupled to a superconductor resonator. Our scheme is able to generate complex photon states for various applications even in the presence of practical imperfections: limited available control of the spin-photon hybrid system and demanding spin decoherence in current state-of-the-art devices.
Microwave-Controlled Generation of Shaped Single Photons in Circuit Quantum Electrodynamics
NASA Astrophysics Data System (ADS)
Pechal, M.; Huthmacher, L.; Eichler, C.; Zeytinoǧlu, S.; Abdumalikov, A. A.; Berger, S.; Wallraff, A.; Filipp, S.
2014-10-01
Large-scale quantum information processors or quantum communication networks will require reliable exchange of information between spatially separated nodes. The links connecting these nodes can be established using traveling photons that need to be absorbed at the receiving node with high efficiency. This is achievable by shaping the temporal profile of the photons and absorbing them at the receiver by time reversing the emission process. Here, we demonstrate a scheme for creating shaped microwave photons using a superconducting transmon-type three-level system coupled to a transmission line resonator. In a second-order process induced by a modulated microwave drive, we controllably transfer a single excitation from the third level of the transmon to the resonator and shape the emitted photon. We reconstruct the density matrices of the created single-photon states and show that the photons are antibunched. We also create multipeaked photons with a controlled amplitude and phase. In contrast to similar existing schemes, the one we present here is based solely on microwave drives, enabling operation with fixed frequency transmons.
NASA Astrophysics Data System (ADS)
Reagor, Matthew; Pfaff, Wolfgang; Heeres, Reinier; Ofek, Nissim; Chou, Kevin; Blumoff, Jacob; Leghtas, Zaki; Touzard, Steven; Sliwa, Katrina; Holland, Eric; Albert, Victor V.; Frunzio, Luigi; Devoret, Michel H.; Jiang, Liang; Schoelkopf, Robert J.
2015-03-01
Recent advances in circuit QED have shown great potential for using microwave resonators as quantum memories. In particular, it is possible to encode the state of a quantum bit in non-classical photonic states inside a high-Q linear resonator. An outstanding challenge is to perform controlled operations on such a photonic state. We demonstrate experimentally how a continuous drive on a transmon qubit coupled to a high-Q storage resonator can be used to induce non-linear dynamics of the resonator. Tailoring the drive properties allows us to cancel or enhance non-linearities in the system such that we can manipulate the state stored in the cavity. This approach can be used to either counteract undesirable evolution due to the bare Hamiltonian of the system or, ultimately, to perform logical operations on the state encoded in the cavity field. Our method provides a promising pathway towards performing universal control for quantum states stored in high-coherence resonators in the circuit QED platform.
Deterministic photon-emitter coupling in chiral photonic circuits.
Söllner, Immo; Mahmoodian, Sahand; Hansen, Sofie Lindskov; Midolo, Leonardo; Javadi, Alisa; Kiršanskė, Gabija; Pregnolato, Tommaso; El-Ella, Haitham; Lee, Eun Hye; Song, Jin Dong; Stobbe, Søren; Lodahl, Peter
2015-09-01
Engineering photon emission and scattering is central to modern photonics applications ranging from light harvesting to quantum-information processing. To this end, nanophotonic waveguides are well suited as they confine photons to a one-dimensional geometry and thereby increase the light-matter interaction. In a regular waveguide, a quantum emitter interacts equally with photons in either of the two propagation directions. This symmetry is violated in nanophotonic structures in which non-transversal local electric-field components imply that photon emission and scattering may become directional. Here we show that the helicity of the optical transition of a quantum emitter determines the direction of single-photon emission in a specially engineered photonic-crystal waveguide. We observe single-photon emission into the waveguide with a directionality that exceeds 90% under conditions in which practically all the emitted photons are coupled to the waveguide. The chiral light-matter interaction enables deterministic and highly directional photon emission for experimentally achievable on-chip non-reciprocal photonic elements. These may serve as key building blocks for single-photon optical diodes, transistors and deterministic quantum gates. Furthermore, chiral photonic circuits allow the dissipative preparation of entangled states of multiple emitters for experimentally achievable parameters, may lead to novel topological photon states and could be applied for directional steering of light. PMID:26214251
Deterministic photon-emitter coupling in chiral photonic circuits
NASA Astrophysics Data System (ADS)
Söllner, Immo; Mahmoodian, Sahand; Hansen, Sofie Lindskov; Midolo, Leonardo; Javadi, Alisa; Kiršanskė, Gabija; Pregnolato, Tommaso; El-Ella, Haitham; Lee, Eun Hye; Song, Jin Dong; Stobbe, Søren; Lodahl, Peter
2015-09-01
Engineering photon emission and scattering is central to modern photonics applications ranging from light harvesting to quantum-information processing. To this end, nanophotonic waveguides are well suited as they confine photons to a one-dimensional geometry and thereby increase the light-matter interaction. In a regular waveguide, a quantum emitter interacts equally with photons in either of the two propagation directions. This symmetry is violated in nanophotonic structures in which non-transversal local electric-field components imply that photon emission and scattering may become directional. Here we show that the helicity of the optical transition of a quantum emitter determines the direction of single-photon emission in a specially engineered photonic-crystal waveguide. We observe single-photon emission into the waveguide with a directionality that exceeds 90% under conditions in which practically all the emitted photons are coupled to the waveguide. The chiral light-matter interaction enables deterministic and highly directional photon emission for experimentally achievable on-chip non-reciprocal photonic elements. These may serve as key building blocks for single-photon optical diodes, transistors and deterministic quantum gates. Furthermore, chiral photonic circuits allow the dissipative preparation of entangled states of multiple emitters for experimentally achievable parameters, may lead to novel topological photon states and could be applied for directional steering of light.
Photonic quantum information: science and technology.
Takeuchi, Shigeki
2016-01-01
Recent technological progress in the generation, manipulation and detection of individual single photons has opened a new scientific field of photonic quantum information. This progress includes the realization of single photon switches, photonic quantum circuits with specific functions, and the application of novel photonic states to novel optical metrology beyond the limits of standard optics. In this review article, the recent developments and current status of photonic quantum information technology are overviewed based on the author's past and recent works. PMID:26755398
Photonic quantum technologies (Presentation Recording)
NASA Astrophysics Data System (ADS)
O'Brien, Jeremy L.
2015-09-01
The impact of quantum technology will be profound and far-reaching: secure communication networks for consumers, corporations and government; precision sensors for biomedical technology and environmental monitoring; quantum simulators for the design of new materials, pharmaceuticals and clean energy devices; and ultra-powerful quantum computers for addressing otherwise impossibly large datasets for machine learning and artificial intelligence applications. However, engineering quantum systems and controlling them is an immense technological challenge: they are inherently fragile; and information extracted from a quantum system necessarily disturbs the system itself. Of the various approaches to quantum technologies, photons are particularly appealing for their low-noise properties and ease of manipulation at the single qubit level. We have developed an integrated waveguide approach to photonic quantum circuits for high performance, miniaturization and scalability. We will described our latest progress in generating, manipulating and interacting single photons in waveguide circuits on silicon chips.
NASA Astrophysics Data System (ADS)
Thylen, Lars
2010-03-01
Nanophotonics and plasmonics have received much attention recently, fuelled by a general interest in nanotechnology but also by rapid advances in integrated photonics, mainly brought about by using silicon, with larger refractive index difference than previously employed [L. Thylen et al, J. Zhejiang Univ. SCIENCE 2006 7(12)]. Plasmonics offers a possibility for devices with field sizes much smaller than the wavelength of light in aa host medium. But the tighter the field confinement, the greater are generally the optical losses, determined by the imaginary part of epsilon. This remains a critical issue. Dissipative losses impede the ubiquitous usefulness of nanophotonics light wave circuits. Recently, optical gain in quantum dots for reducing or compensate losses was analyzed [A Bratkovsky et al, Applied Physics Letters 93, 193106 (2008)]. However, the concomitant effects of the high (but not unreachable) gain required for this are high power dissipation and signal to noise ratio degradation. Power dissipation is primarily due to the losses of the metal structures and Auger recombination in the quantum dots. A general and square chip size independent expression for the information capacity of a lossless (by amplification) plasmonic chip is given, using the allowed values for integrated electronics power dissipation. In conclusion, with amplification and with current understanding, it appears possible to sizewise come close to CMOS dimensions for isolated integrated photonic devices, but not in integration density. This is due to power dissipation in currently employed negative epsilon materials.
Quantum interference in plasmonic circuits.
Heeres, Reinier W; Kouwenhoven, Leo P; Zwiller, Valery
2013-10-01
Surface plasmon polaritons (plasmons) are a combination of light and a collective oscillation of the free electron plasma at metal/dielectric interfaces. This interaction allows subwavelength confinement of light beyond the diffraction limit inherent to dielectric structures. As a result, the intensity of the electromagnetic field is enhanced, with the possibility to increase the strength of the optical interactions between waveguides, light sources and detectors. Plasmons maintain non-classical photon statistics and preserve entanglement upon transmission through thin, patterned metallic films or weakly confining waveguides. For quantum applications, it is essential that plasmons behave as indistinguishable quantum particles. Here we report on a quantum interference experiment in a nanoscale plasmonic circuit consisting of an on-chip plasmon beamsplitter with integrated superconducting single-photon detectors to allow efficient single plasmon detection. We demonstrate a quantum-mechanical interaction between pairs of indistinguishable surface plasmons by observing Hong-Ou-Mandel (HOM) interference, a hallmark non-classical interference effect that is the basis of linear optics-based quantum computation. Our work shows that it is feasible to shrink quantum optical experiments to the nanoscale and offers a promising route towards subwavelength quantum optical networks. PMID:23934097
Quantum interference in plasmonic circuits
NASA Astrophysics Data System (ADS)
Heeres, Reinier W.; Kouwenhoven, Leo P.; Zwiller, Valery
2013-10-01
Surface plasmon polaritons (plasmons) are a combination of light and a collective oscillation of the free electron plasma at metal/dielectric interfaces. This interaction allows subwavelength confinement of light beyond the diffraction limit inherent to dielectric structures. As a result, the intensity of the electromagnetic field is enhanced, with the possibility to increase the strength of the optical interactions between waveguides, light sources and detectors. Plasmons maintain non-classical photon statistics and preserve entanglement upon transmission through thin, patterned metallic films or weakly confining waveguides. For quantum applications, it is essential that plasmons behave as indistinguishable quantum particles. Here we report on a quantum interference experiment in a nanoscale plasmonic circuit consisting of an on-chip plasmon beamsplitter with integrated superconducting single-photon detectors to allow efficient single plasmon detection. We demonstrate a quantum-mechanical interaction between pairs of indistinguishable surface plasmons by observing Hong-Ou-Mandel (HOM) interference, a hallmark non-classical interference effect that is the basis of linear optics-based quantum computation. Our work shows that it is feasible to shrink quantum optical experiments to the nanoscale and offers a promising route towards subwavelength quantum optical networks.
A scheme for two-photon lasing with two coupled flux qubits in circuit quantum electrodynamics
NASA Astrophysics Data System (ADS)
Huang, Wen; Zou, Xu-Bo; Guo, Guang-Can
2015-06-01
We theoretically study the system of a superconducting transmission line resonator coupled to two interacting superconducting flux qubits. It is shown that under certain conditions the resonator mode can be tuned to two-photon resonance between the ground state and the highest excited state while the middle excited states are far-off resonance. Furthermore, we study the steady-state properties of the flux qubits and resonator, such as the photon statistics, the spectrum and squeezing of the resonator, and demonstrate that two-photon laser can be implemented with current experimental technology. Project supported by the National Fundamental Research Program of China (Grant No. 2011cba00200), the National Natural Science Foundation of China (Grant No. 11274295), and the Doctor Foundation of Education Ministry of China (Grant No. 20113402110059).
Wang, Ruijun; Sprengel, Stephan; Muneeb, Muhammad; Boehm, Gerhard; Baets, Roel; Amann, Markus-Christian; Roelkens, Gunther
2015-10-01
The heterogeneous integration of InP-based type-II quantum well photodiodes on silicon photonic integrated circuits for the 2 µm wavelength range is presented. A responsivity of 1.2 A/W at a wavelength of 2.32 µm and 0.6 A/W at 2.4 µm wavelength is demonstrated. The photodiodes have a dark current of 12 nA at -0.5 V at room temperature. The absorbing active region of the integrated photodiodes consists of six periods of a "W"-shaped quantum well, also allowing for laser integration on the same platform. PMID:26480194
Automated Design of Quantum Circuits
NASA Technical Reports Server (NTRS)
Williams, C.; Gray, G.
1998-01-01
In order to design a quantum circuit that performs a desired quantum computation, it is necessary to find a decomposition of the unitary matrix that represents that computation in terms of a sequence of quantum gate operations.
Quantum Computing using Photons
NASA Astrophysics Data System (ADS)
Elhalawany, Ahmed; Leuenberger, Michael
2013-03-01
In this work, we propose a theoretical model of two-quantum bit gates for quantum computation using the polarization states of two photons in a microcavity. By letting the two photons interact non-resonantly with four quantum dots inside the cavity, we obtain an effective photon-photon interaction which we exploit for the implementation of an universal XOR gate. The two-photon Hamiltonian is written in terms of the photons' total angular momentum operators and their states are written using the Schwinger representation of the total angular momentum.
Waveguide-QED-Based Photonic Quantum Computation
NASA Astrophysics Data System (ADS)
Zheng, Huaixiu; Gauthier, Daniel J.; Baranger, Harold U.
2013-08-01
We propose a new scheme for quantum computation using flying qubits—propagating photons in a one-dimensional waveguide interacting with matter qubits. Photon-photon interactions are mediated by the coupling to a four-level system, based on which photon-photon π-phase gates (controlled-not) can be implemented for universal quantum computation. We show that high gate fidelity is possible, given recent dramatic experimental progress in superconducting circuits and photonic-crystal waveguides. The proposed system can be an important building block for future on-chip quantum networks.
Photonic quantum information: science and technology
TAKEUCHI, Shigeki
2016-01-01
Recent technological progress in the generation, manipulation and detection of individual single photons has opened a new scientific field of photonic quantum information. This progress includes the realization of single photon switches, photonic quantum circuits with specific functions, and the application of novel photonic states to novel optical metrology beyond the limits of standard optics. In this review article, the recent developments and current status of photonic quantum information technology are overviewed based on the author’s past and recent works. PMID:26755398
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. PMID:20588656
Automated Design of Quantum Circuits
NASA Technical Reports Server (NTRS)
Williams, Colin P.; Gray, Alexander G.
2000-01-01
In order to design a quantum circuit that performs a desired quantum computation, it is necessary to find a decomposition of the unitary matrix that represents that computation in terms of a sequence of quantum gate operations. To date, such designs have either been found by hand or by exhaustive enumeration of all possible circuit topologies. In this paper we propose an automated approach to quantum circuit design using search heuristics based on principles abstracted from evolutionary genetics, i.e. using a genetic programming algorithm adapted specially for this problem. We demonstrate the method on the task of discovering quantum circuit designs for quantum teleportation. We show that to find a given known circuit design (one which was hand-crafted by a human), the method considers roughly an order of magnitude fewer designs than naive enumeration. In addition, the method finds novel circuit designs superior to those previously known.
Quantum photonics hybrid integration platform
Murray, E.; Floether, F. F.; Ellis, D. J. P.; Meany, T.; Bennett, A. J. Shields, A. J.; Lee, J. P.; Griffiths, J. P.; Jones, G. A. C.; Farrer, I.; Ritchie, D. A.
2015-10-26
Fundamental to integrated photonic quantum computing is an on-chip method for routing and modulating quantum light emission. We demonstrate a hybrid integration platform consisting of arbitrarily designed waveguide circuits and single-photon sources. InAs quantum dots (QD) embedded in GaAs are bonded to a SiON waveguide chip such that the QD emission is coupled to the waveguide mode. The waveguides are SiON core embedded in a SiO{sub 2} cladding. A tuneable Mach Zehnder interferometer (MZI) modulates the emission between two output ports and can act as a path-encoded qubit preparation device. The single-photon nature of the emission was verified using the on-chip MZI as a beamsplitter in a Hanbury Brown and Twiss measurement.
Circuit electromechanics with single photon strong coupling
Xue, Zheng-Yuan Yang, Li-Na; Zhou, Jian
2015-07-13
In circuit electromechanics, the coupling strength is usually very small. Here, replacing the capacitor in circuit electromechanics by a superconducting flux qubit, we show that the coupling among the qubit and the two resonators can induce effective electromechanical coupling which can attain the strong coupling regime at the single photon level with feasible experimental parameters. We use dispersive couplings among two resonators and the qubit while the qubit is also driven by an external classical field. These couplings form a three-wave mixing configuration among the three elements where the qubit degree of freedom can be adiabatically eliminated, and thus results in the enhanced coupling between the two resonators. Therefore, our work constitutes the first step towards studying quantum nonlinear effect in circuit electromechanics.
NASA Astrophysics Data System (ADS)
Barz, Stefanie
2013-05-01
Quantum physics has revolutionized our understanding of information processing and enables computational speed-ups that are unattainable using classical computers. In this talk I will present a series of experiments in the field of photonic quantum computing. The first experiment is in the field of photonic state engineering and realizes the generation of heralded polarization-entangled photon pairs. It overcomes the limited applicability of photon-based schemes for quantum information processing tasks, which arises from the probabilistic nature of photon generation. The second experiment uses polarization-entangled photonic qubits to implement ``blind quantum computing,'' a new concept in quantum computing. Blind quantum computing enables a nearly-classical client to access the resources of a more computationally-powerful quantum server without divulging the content of the requested computation. Finally, the concept of blind quantum computing is applied to the field of verification. A new method is developed and experimentally demonstrated, which verifies the entangling capabilities of a quantum computer based on a blind Bell test.
Quantum teleportation on a photonic chip
NASA Astrophysics Data System (ADS)
Metcalf, Benjamin J.; Spring, Justin B.; Humphreys, Peter C.; Thomas-Peter, Nicholas; Barbieri, Marco; Kolthammer, W. Steven; Jin, Xian-Min; Langford, Nathan K.; Kundys, Dmytro; Gates, James C.; Smith, Brian J.; Smith, Peter G. R.; Walmsley, Ian A.
2014-10-01
Quantum teleportation is a fundamental concept in quantum physics that now finds important applications at the heart of quantum technology, including quantum relays, quantum repeaters and linear optics quantum computing. Photonic implementations have largely focused on achieving long-distance teleportation for decoherence-free quantum communication. Teleportation also plays a vital role in photonic quantum computing, for which large linear optical networks will probably require an integrated architecture. Here, we report a fully integrated implementation of quantum teleportation in which all key parts of the circuit—entangled state preparation, Bell-state analysis and tomographic state measurement—are performed on a reconfigurable photonic chip. We also show that a novel element-wise characterization method is critical to the mitigation of component errors, a key technique that will become increasingly important as integrated circuits reach the higher complexities necessary for quantum enhanced operation.
A quantum photonic dissipative transport theory
NASA Astrophysics Data System (ADS)
Lei, Chan U.; Zhang, Wei-Min
2012-05-01
In this paper, a quantum transport theory for describing photonic dissipative transport dynamics in nanophotonics is developed. The nanophotonic devices concerned in this paper consist of on-chip all-optical integrated circuits incorporating photonic bandgap waveguides and driven resonators embedded in nanostructured photonic crystals. The photonic transport through waveguides is entirely determined from the exact master equation of the driven resonators, which is obtained by explicitly eliminating all the degrees of freedom of the waveguides (treated as reservoirs). Back-reactions from the reservoirs are fully taken into account. The relation between the driven photonic dynamics and photocurrents is obtained explicitly. The non-Markovian memory structure and quantum decoherence dynamics in photonic transport can then be fully addressed. As an illustration, the theory is utilized to study the transport dynamics of a photonic transistor consisting of a nanocavity coupled to two waveguides in photonic crystals. The controllability of photonic transport through the external driven field is demonstrated.
Photonic realization of the quantum Rabi model.
Crespi, A; Longhi, S; Osellame, R
2012-04-20
We realize a photonic analog simulator of the quantum Rabi model, based on light transport in femtosecond-laser-written waveguide superlattices, which provides an experimentally accessible test bed to explore the physics of light-matter interaction in the deep strong coupling regime. Our optical setting enables us to visualize dynamical regimes not yet accessible in cavity or circuit quantum electrodynamics, such as the bouncing of photon number wave packets in parity chains of Hilbert space. PMID:22680717
All-photonic quantum repeaters
NASA Astrophysics Data System (ADS)
Azuma, Koji; Tamaki, Kiyoshi; Lo, Hoi-Kwong
2015-04-01
Quantum communication holds promise for unconditionally secure transmission of secret messages and faithful transfer of unknown quantum states. Photons appear to be the medium of choice for quantum communication. Owing to photon losses, robust quantum communication over long lossy channels requires quantum repeaters. It is widely believed that a necessary and highly demanding requirement for quantum repeaters is the existence of matter quantum memories. Here we show that such a requirement is, in fact, unnecessary by introducing the concept of all-photonic quantum repeaters based on flying qubits. In particular, we present a protocol based on photonic cluster-state machine guns and a loss-tolerant measurement equipped with local high-speed active feedforwards. We show that, with such all-photonic quantum repeaters, the communication efficiency scales polynomially with the channel distance. Our result paves a new route towards quantum repeaters with efficient single-photon sources rather than matter quantum memories.
All-photonic quantum repeaters.
Azuma, Koji; Tamaki, Kiyoshi; Lo, Hoi-Kwong
2015-01-01
Quantum communication holds promise for unconditionally secure transmission of secret messages and faithful transfer of unknown quantum states. Photons appear to be the medium of choice for quantum communication. Owing to photon losses, robust quantum communication over long lossy channels requires quantum repeaters. It is widely believed that a necessary and highly demanding requirement for quantum repeaters is the existence of matter quantum memories. Here we show that such a requirement is, in fact, unnecessary by introducing the concept of all-photonic quantum repeaters based on flying qubits. In particular, we present a protocol based on photonic cluster-state machine guns and a loss-tolerant measurement equipped with local high-speed active feedforwards. We show that, with such all-photonic quantum repeaters, the communication efficiency scales polynomially with the channel distance. Our result paves a new route towards quantum repeaters with efficient single-photon sources rather than matter quantum memories. PMID:25873153
All-photonic quantum repeaters
Azuma, Koji; Tamaki, Kiyoshi; Lo, Hoi-Kwong
2015-01-01
Quantum communication holds promise for unconditionally secure transmission of secret messages and faithful transfer of unknown quantum states. Photons appear to be the medium of choice for quantum communication. Owing to photon losses, robust quantum communication over long lossy channels requires quantum repeaters. It is widely believed that a necessary and highly demanding requirement for quantum repeaters is the existence of matter quantum memories. Here we show that such a requirement is, in fact, unnecessary by introducing the concept of all-photonic quantum repeaters based on flying qubits. In particular, we present a protocol based on photonic cluster-state machine guns and a loss-tolerant measurement equipped with local high-speed active feedforwards. We show that, with such all-photonic quantum repeaters, the communication efficiency scales polynomially with the channel distance. Our result paves a new route towards quantum repeaters with efficient single-photon sources rather than matter quantum memories. PMID:25873153
Design methodologies for silicon photonic integrated circuits
NASA Astrophysics Data System (ADS)
Chrostowski, Lukas; Flueckiger, Jonas; Lin, Charlie; Hochberg, Michael; Pond, James; Klein, Jackson; Ferguson, John; Cone, Chris
2014-03-01
This paper describes design methodologies developed for silicon photonics integrated circuits. The approach presented is inspired by methods employed in the Electronics Design Automation (EDA) community. This is complemented by well established photonic component design tools, compact model synthesis, and optical circuit modelling. A generic silicon photonics design kit, as described here, is available for download at http://www.siepic.ubc.ca/GSiP.
Quantum efficiency of a double quantum dot microwave photon detector
NASA Astrophysics Data System (ADS)
Wong, Clement; Vavilov, Maxim
Motivated by recent interest in implementing circuit quantum electrodynamics with semiconducting quantum dots, we study charge transfer through a double quantum dot (DQD) capacitively coupled to a superconducting cavity subject to a microwave field. We analyze the DQD current response using input-output theory and determine the optimal parameter regime for complete absorption of radiation and efficient conversion of microwave photons to electric current. For experimentally available DQD systems, we show that the cavity-coupled DQD operates as a photon-to-charge converter with quantum efficiencies up to 80% C.W. acknowledges support by the Intelligence Community Postdoctoral Research Fellowship Program.
Yamashita, Taro; Miki, Shigehito; Terai, Hirotaka; Makise, Kazumasa; Wang, Zhen
2012-07-15
We demonstrate the successful operation of a multielement superconducting nanowire single-photon detector (SSPD) array integrated with a single-flux-quantum (SFQ) readout circuit in a compact 0.1 W Gifford-McMahon cryocooler. A time-resolved readout technique, where output signals from each element enter the SFQ readout circuit with finite time intervals, revealed crosstalk-free operation of the four-element SSPD array connected with the SFQ readout circuit. The timing jitter and the system detection efficiency were measured to be 50 ps and 11.4%, respectively, which were comparable to the performance of practical single-pixel SSPD systems. PMID:22825199
Wang, Ruijun; Sprengel, Stephan; Boehm, Gerhard; Muneeb, Muhammad; Baets, Roel; Amann, Markus-Christian; Roelkens, Gunther
2016-09-01
Heterogeneously integrated InP-based type-II quantum well Fabry-Perot lasers on a silicon waveguide circuit emitting in the 2.3 µm wavelength range are demonstrated. The devices consist of a "W"-shaped InGaAs/GaAsSb multi-quantum-well gain section, III-V/silicon spot size converters and two silicon Bragg grating reflectors to form the laser cavity. In continuous-wave (CW) operation, we obtain a threshold current density of 2.7 kA/cm^{2} and output power of 1.3 mW at 5 °C for 2.35 μm lasers. The lasers emit over 3.7 mW of peak power with a threshold current density of 1.6 kA/cm^{2} in pulsed regime at room temperature. This demonstration of heterogeneously integrated lasers indicates that the material system and heterogeneous integration method are promising to realize fully integrated III-V/silicon photonics spectroscopic sensors in the 2 µm wavelength range. PMID:27607711
Tunable resonant structures for photonic integrated circuits
NASA Astrophysics Data System (ADS)
Ptasinski, Joanna Nina
Photonics is an evolving field allowing for optical devices to be made cost effectively using standard semiconductor fabrication techniques, which in turn enables integration with microelectronic chips. Chip scale photonics will play an increasing role in the future of communications as the demand for bandwidth and reduced power consumption per bit continues to grow. Tunable optical circuit components are one of the essential technologies in the development of photonic analogues for classical electronic devices, where tunable photonic resonant structures allow for altering of their electromagnetic spectrum and find applications in optical switching, filtering, buffering, lasers and biosensors. The scope of this work is focused on tunable resonant structures for photonic integrated circuits. Specifically, this work demonstrates active tuning of silicon photonic resonant structures using the properties of dye doped nematic liquid crystals, temperature stabilization of silicon photonics using the passive properties of liquid crystals, and the effects of low density plasma enhanced chemical vapor deposition (PECVD) claddings on ring resonator device performance.
Decoupling with Random Quantum Circuits
NASA Astrophysics Data System (ADS)
Brown, Winton; Fawzi, Omar
2015-12-01
Decoupling has become a central concept in quantum information theory, with applications including proving coding theorems, randomness extraction and the study of conditions for reaching thermal equilibrium. However, our understanding of the dynamics that lead to decoupling is limited. In fact, the only families of transformations that are known to lead to decoupling are (approximate) unitary two-designs, i.e., measures over the unitary group that behave like the Haar measure as far as the first two moments are concerned. Such families include for example random quantum circuits with O( n 2) gates, where n is the number of qubits in the system under consideration. In fact, all known constructions of decoupling circuits use Ω( n 2) gates. Here, we prove that random quantum circuits with O( n log2 n) gates satisfy an essentially optimal decoupling theorem. In addition, these circuits can be implemented in depth O(log3 n). This proves that decoupling can happen in a time that scales polylogarithmically in the number of particles in the system, provided all the particles are allowed to interact. Our proof does not proceed by showing that such circuits are approximate two-designs in the usual sense, but rather we directly analyze the decoupling property.
Optical coupling to monolithic integrated photonic circuits
NASA Astrophysics Data System (ADS)
Palen, Edward
2007-02-01
Methods of coupling optical fiber and light sources to monolithic integrated photonic circuits are needed to expand future photonics communications markets. Requirements are low cost, high coupling efficiencies, and scalability to high volume production rates. Key features of the different optical coupling options will be discussed along with implementation examples. Requirements for low cost optical coupling and high volume production scalability will be shared.
Holonomic quantum computation on microwave photons with all resonant interactions
NASA Astrophysics Data System (ADS)
Dong, Ping; Yu, Long-Bao; Zhou, Jian
2016-08-01
The intrinsic difficulties of holonomic quantum computation on superconducting circuits are originated from the use of three levels in superconducting transmon qubits and the complicated dispersive interaction between them. Due to the limited anharmonicity of transmon qubits, the experimental realization seems to be very challenging. However, with recent experimental progress, coherent control over microwave photons in superconducting circuit cavities is well achieved, and thus provides a promising platform for quantum information processing with photonic qubits. Here, with all resonant inter-cavity photon–photon interactions, we propose a scheme for implementing scalable holonomic quantum computation on a circuit QED lattice. In our proposal, three cavities, connected by a SQUID, are used to encode a logical qubit. By tuning the inter-cavity photon–photon interaction, we can construct all the holonomies needed for universal quantum computation in a non-adiabatic way. Therefore, our scheme presents a promising alternative for robust quantum computation with microwave photons.
Quantum circuits for isometries
NASA Astrophysics Data System (ADS)
Iten, Raban; Colbeck, Roger; Kukuljan, Ivan; Home, Jonathan; Christandl, Matthias
2016-03-01
We consider the decomposition of arbitrary isometries into a sequence of single-qubit and controlled-not (cnot) gates. In many experimental architectures, the cnot gate is relatively costly and hence we aim to keep the number of these as low as possible. We derive a theoretical lower bound on the number of cnot gates required to decompose an arbitrary isometry from m to n qubits and give three explicit gate decompositions that achieve this bound up to a factor of about 2 in the leading order. We also perform some further optimizations for certain cases where m and n are small. In addition, we show how to apply our result for isometries to give a decomposition scheme for an arbitrary quantum operation via Stinespring's theorem and derive a lower bound on the number of cnot gates in this case too. These results will have an impact on experimental efforts to build a quantum computer, enabling them to go further with the same resources.
Planar Multilayer Circuit Quantum Electrodynamics
NASA Astrophysics Data System (ADS)
Minev, Z. K.; Serniak, K.; Pop, I. M.; Leghtas, Z.; Sliwa, K.; Hatridge, M.; Frunzio, L.; Schoelkopf, R. J.; Devoret, M. H.
2016-04-01
Experimental quantum information processing with superconducting circuits is rapidly advancing, driven by innovation in two classes of devices, one involving planar microfabricated (2D) resonators, and the other involving machined three-dimensional (3D) cavities. We demonstrate that circuit quantum electrodynamics can be implemented in a multilayer superconducting structure that combines 2D and 3D advantages. We employ standard microfabrication techniques to pattern each layer, and rely on a vacuum gap between the layers to store the electromagnetic energy. Planar qubits are lithographically defined as an aperture in a conducting boundary of the resonators. We demonstrate the aperture concept by implementing an integrated, two-cavity-mode, one-transmon-qubit system.
Towards Quantum Information Processing with Superconducting Circuits
NASA Astrophysics Data System (ADS)
Schoelkopf, Robert
2011-03-01
In the dozen years since the initial demonstrations that superconducting circuits based on Josephson junctions could be considered as qubits, there has been remarkable progress in the field. Several different ``species'' of these artificial atoms have been designed and tested, and coherence times have increased by more than 1,000, or a factor of 10 every three years. While real devices are still far from satisfying all the DiVincenzo criteria with fidelities that would meet the error correction threshold, one can nonetheless perform preparation, control, quantum logic, and measurement on multiple superconducting qubits, all with surprisingly high purity and precision given that these are man-made, solid-state systems. In recent years we have seen the preparation of highly-entangled multi-qubit states that violate the Bell and Mermin inequalities, as well as the demonstration of single quantum algorithms, which all benefit from the strong coupling, addressability, and all-electronic control that is possible with these systems. Many experiments employ the concept of a ``quantum bus,'' where qubits couple via superconducting transmission lines that form high-quality resonant cavities. A spinoff of this work is the advent of quantum optics on a chip: microwaves are photons too! The combination of qubits coupled to cavities has allowed the preparation and detection of single gigahertz photons, as well as other highly non-classical states of microwave light. Great progress has also been made in quantum measurement, and other Josephson circuits are now delivering amplifiers that operate at or beyond the Heisenberg limit. In this talk I will attempt to give an overview of some of the key concepts, some experimental highlights from recent years, and point out some possible directions for the future in this field. I would like to acknowledge all my collaborators at Yale, and funding from ARO, NSA/LPS, NSF, and IARPA.
Multimode quantum interference of photons in multiport integrated devices
Peruzzo, Alberto; Laing, Anthony; Politi, Alberto; Rudolph, Terry; O'Brien, Jeremy L.
2011-01-01
Photonics is a leading approach in realizing future quantum technologies and recently, optical waveguide circuits on silicon chips have demonstrated high levels of miniaturization and performance. Multimode interference (MMI) devices promise a straightforward implementation of compact and robust multiport circuits. Here, we show quantum interference in a 2×2 MMI coupler with visibility of V=95.6±0.9%. We further demonstrate the operation of a 4×4 port MMI device with photon pairs, which exhibits complex quantum interference behaviour. We have developed a new technique to fully characterize such multiport devices, which removes the need for phase-sensitive measurements and may find applications for a wide range of photonic devices. Our results show that MMI devices can operate in the quantum regime with high fidelity and promise substantial simplification and concatenation of photonic quantum circuits. PMID:21364563
Photonic crystal chips for optical communications and quantum information processing
NASA Astrophysics Data System (ADS)
Englund, Dirk; Fushman, Ilya; Faraon, Andrei; Ellis, Bryan; Vučković, Jelena
2008-08-01
We discuss recent our recent progress on functional photonic crystals devices and circuits for classical and quantum information processing. For classical applications, we have demonstrated a room-temperature-operated, low threshold, nanocavity laser with pulse width in the picosecond regime; and an all-optical switch controlled with 60 fJ pulses that shows switching time on the order of tens of picoseconds. For quantum information processing, we discuss the promise of quantum networks on multifunctional photonic crystals chips. We also discuss a new coherent probing technique of quantum dots coupled to photonic crystal nanocavities and demonstrate amplitude and phase nonlinearities realized with control beams at the single photon level.
Silicon nitride microwave photonic circuits.
Roeloffzen, Chris G H; Zhuang, Leimeng; Taddei, Caterina; Leinse, Arne; Heideman, René G; van Dijk, Paulus W L; Oldenbeuving, Ruud M; Marpaung, David A I; Burla, Maurizio; Boller, Klaus-J
2013-09-23
We present an overview of several microwave photonic processing functionalities based on combinations of Mach-Zehnder and ring resonator filters using the high index contrast silicon nitride (TriPleX™) waveguide technology. All functionalities are built using the same basic building blocks, namely straight waveguides, phase tuning elements and directional couplers. We recall previously shown measurements on high spurious free dynamic range microwave photonic (MWP) link, ultra-wideband pulse generation, instantaneous frequency measurements, Hilbert transformers, microwave polarization networks and demonstrate new measurements and functionalities on a 16 channel optical beamforming network and modulation format transformer as well as an outlook on future microwave photonic platform integration, which will lead to a significantly reduced footprint and thereby enables the path to commercially viable MWP systems. PMID:24104179
Atemporal diagrams for quantum circuits
Griffiths, Robert B.; Wu Shengjun; Yu Li; Cohen, Scott M.
2006-05-15
A system of diagrams is introduced that allows the representation of various elements of a quantum circuit, including measurements, in a form which makes no reference to time (hence 'atemporal'). It can be used to relate quantum dynamical properties to those of entangled states (map-state duality), and suggests useful analogies, such as the inverse of an entangled ket. Diagrams clarify the role of channel kets, transition operators, dynamical operators (matrices), and Kraus rank for noisy quantum channels. Positive (semidefinite) operators are represented by diagrams with a symmetry that aids in understanding their connection with completely positive maps. The diagrams are used to analyze standard teleportation and dense coding, and for a careful study of unambiguous (conclusive) teleportation. A simple diagrammatic argument shows that a Kraus rank of 3 is impossible for a one-qubit channel modeled using a one-qubit environment in a mixed state.
Physical synthesis of quantum circuits using templates
NASA Astrophysics Data System (ADS)
Mirkhani, Zahra; Mohammadzadeh, Naser
2016-06-01
Similar to traditional CMOS circuits, quantum circuit design flow is divided into two main processes: logic synthesis and physical design. Addressing the limitations imposed on optimization of the quantum circuit metrics because of no information sharing between logic synthesis and physical design processes, the concept of "physical synthesis" was introduced for quantum circuit flow, and a few techniques were proposed for it. Following that concept, in this paper a new approach for physical synthesis inspired by template matching idea in quantum logic synthesis is proposed to improve the latency of quantum circuits. Experiments show that by using template matching as a physical synthesis approach, the latency of quantum circuits can be improved by more than 23.55 % on average.
Detecting photon-photon interactions in a superconducting circuit
NASA Astrophysics Data System (ADS)
Jin, Li-Jing; Houzet, Manuel; Meyer, Julia S.; Baranger, Harold U.; Hekking, Frank W. J.
2015-10-01
A local interaction between photons can be engineered by coupling a nonlinear system to a transmission line. The required transmission line can be conveniently formed from a chain of Josephson junctions. The nonlinearity is generated by side-coupling this chain to a Cooper pair box. We propose to probe the resulting photon-photon interactions via their effect on the current-voltage characteristic of a voltage-biased Josephson junction connected to the transmission line. Considering the Cooper pair box to be in the weakly anharmonic regime, we find that the dc current through the probe junction yields features around the voltages 2 e V =n ℏ ωs , where ωs is the plasma frequency of the superconducting circuit. The features at n ≥2 are a direct signature of the photon-photon interaction in the system.
Two-photon tomography using on-chip quantum walks.
Titchener, James G; Solntsev, Alexander S; Sukhorukov, Andrey A
2016-09-01
We present an approach to quantum tomography based on first expanding a quantum state across extra degrees of freedom and then exploiting the introduced sparsity to perform reconstruction. We formulate its application to photonic circuits and show that measured spatial photon correlations at the output of a specially tailored discrete-continuous quantum walk can enable full reconstruction of any two-photon spatially entangled and mixed state at the input. This approach does not require any tunable elements, so it is well suited for integration with on-chip superconducting photon detectors. PMID:27607977
Integrated photonic quantum gates for polarization qubits
Crespi, Andrea; Ramponi, Roberta; Osellame, Roberto; Sansoni, Linda; Bongioanni, Irene; Sciarrino, Fabio; Vallone, Giuseppe; Mataloni, Paolo
2011-01-01
The ability to manipulate quantum states of light by integrated devices may open new perspectives both for fundamental tests of quantum mechanics and for novel technological applications. However, the technology for handling polarization-encoded qubits, the most commonly adopted approach, is still missing in quantum optical circuits. Here we demonstrate the first integrated photonic controlled-NOT (CNOT) gate for polarization-encoded qubits. This result has been enabled by the integration, based on femtosecond laser waveguide writing, of partially polarizing beam splitters on a glass chip. We characterize the logical truth table of the quantum gate demonstrating its high fidelity to the expected one. In addition, we show the ability of this gate to transform separable states into entangled ones and vice versa. Finally, the full accessibility of our device is exploited to carry out a complete characterization of the CNOT gate through a quantum process tomography. PMID:22127062
Reliable quantum certification of photonic state preparations
Aolita, Leandro; Gogolin, Christian; Kliesch, Martin; Eisert, Jens
2015-01-01
Quantum technologies promise a variety of exciting applications. Even though impressive progress has been achieved recently, a major bottleneck currently is the lack of practical certification techniques. The challenge consists of ensuring that classically intractable quantum devices perform as expected. Here we present an experimentally friendly and reliable certification tool for photonic quantum technologies: an efficient certification test for experimental preparations of multimode pure Gaussian states, pure non-Gaussian states generated by linear-optical circuits with Fock-basis states of constant boson number as inputs, and pure states generated from the latter class by post-selecting with Fock-basis measurements on ancillary modes. Only classical computing capabilities and homodyne or hetorodyne detection are required. Minimal assumptions are made on the noise or experimental capabilities of the preparation. The method constitutes a step forward in many-body quantum certification, which is ultimately about testing quantum mechanics at large scales. PMID:26577800
Developing A Quantum Circuit Simulator API
NASA Astrophysics Data System (ADS)
Mihai Dorian, Stancu; Emil Marin, Popa
2015-09-01
In this paper we propose the design and implementation of a quantum circuit simulator API. Currently the API allows users to implement, debug and test the following two quantum algorithms: Bernstein-Vazirani's algorithm and Simon's Algorithm. The goal is to create a framework that will allow quantum computer scientists to easily develop new quantum algorithms.
Deterministic Integration of Single Photon Sources in Silicon Based Photonic Circuits.
Zadeh, Iman Esmaeil; Elshaari, Ali W; Jöns, Klaus D; Fognini, Andreas; Dalacu, Dan; Poole, Philip J; Reimer, Michael E; Zwiller, Val
2016-04-13
A major step toward fully integrated quantum optics is the deterministic incorporation of high quality single photon sources in on-chip optical circuits. We show a novel hybrid approach in which preselected III-V single quantum dots in nanowires are transferred and integrated in silicon based photonic circuits. The quantum emitters maintain their high optical quality after integration as verified by measuring a low multiphoton probability of 0.07 ± 0.07 and emission line width as narrow as 3.45 ± 0.48 GHz. Our approach allows for optimum alignment of the quantum dot light emission to the fundamental waveguide mode resulting in very high coupling efficiencies. We estimate a coupling efficiency of 24.3 ± 1.7% from the studied single-photon source to the photonic channel and further show by finite-difference time-domain simulations that for an optimized choice of material and design the efficiency can exceed 90%. PMID:26954298
A scanning transmon qubit for strong coupling circuit quantum electrodynamics.
Shanks, W E; Underwood, D L; Houck, A A
2013-01-01
Like a quantum computer designed for a particular class of problems, a quantum simulator enables quantitative modelling of quantum systems that is computationally intractable with a classical computer. Superconducting circuits have recently been investigated as an alternative system in which microwave photons confined to a lattice of coupled resonators act as the particles under study, with qubits coupled to the resonators producing effective photon-photon interactions. Such a system promises insight into the non-equilibrium physics of interacting bosons, but new tools are needed to understand this complex behaviour. Here we demonstrate the operation of a scanning transmon qubit and propose its use as a local probe of photon number within a superconducting resonator lattice. We map the coupling strength of the qubit to a resonator on a separate chip and show that the system reaches the strong coupling regime over a wide scanning area. PMID:23744062
Programmable atom-photon quantum interface
NASA Astrophysics Data System (ADS)
Kurz, Christoph; Eich, Pascal; Schug, Michael; Müller, Philipp; Eschner, Jürgen
2016-06-01
We present the implementation of a programmable atom-photon quantum interface, employing a single trapped +40Ca ion and single photons. Depending on its mode of operation, the interface serves as a bidirectional atom-photon quantum-state converter, as a source of entangled atom-photon states, or as a quantum frequency converter of single photons. The interface lends itself particularly to interfacing ions with spontaneous parametric down-conversion-based single-photon or entangled-photon-pair sources.
Two-photon quantum walk in a multimode fiber
Defienne, Hugo; Barbieri, Marco; Walmsley, Ian A.; Smith, Brian J.; Gigan, Sylvain
2016-01-01
Multiphoton propagation in connected structures—a quantum walk—offers the potential of simulating complex physical systems and provides a route to universal quantum computation. Increasing the complexity of quantum photonic networks where the walk occurs is essential for many applications. We implement a quantum walk of indistinguishable photon pairs in a multimode fiber supporting 380 modes. Using wavefront shaping, we control the propagation of the two-photon state through the fiber in which all modes are coupled. Excitation of arbitrary output modes of the system is realized by controlling classical and quantum interferences. This report demonstrates a highly multimode platform for multiphoton interference experiments and provides a powerful method to program a general high-dimensional multiport optical circuit. This work paves the way for the next generation of photonic devices for quantum simulation, computing, and communication. PMID:27152325
Two-photon quantum walk in a multimode fiber.
Defienne, Hugo; Barbieri, Marco; Walmsley, Ian A; Smith, Brian J; Gigan, Sylvain
2016-01-01
Multiphoton propagation in connected structures-a quantum walk-offers the potential of simulating complex physical systems and provides a route to universal quantum computation. Increasing the complexity of quantum photonic networks where the walk occurs is essential for many applications. We implement a quantum walk of indistinguishable photon pairs in a multimode fiber supporting 380 modes. Using wavefront shaping, we control the propagation of the two-photon state through the fiber in which all modes are coupled. Excitation of arbitrary output modes of the system is realized by controlling classical and quantum interferences. This report demonstrates a highly multimode platform for multiphoton interference experiments and provides a powerful method to program a general high-dimensional multiport optical circuit. This work paves the way for the next generation of photonic devices for quantum simulation, computing, and communication. PMID:27152325
Josephson Circuits as Vector Quantum Spins
NASA Astrophysics Data System (ADS)
Samach, Gabriel; Kerman, Andrew J.
While superconducting circuits based on Josephson junction technology can be engineered to represent spins in the quantum transverse-field Ising model, no circuit architecture to date has succeeded in emulating the vector quantum spin models of interest for next-generation quantum annealers and quantum simulators. Here, we present novel Josephson circuits which may provide these capabilities. We discuss our rigorous quantum-mechanical simulations of these circuits, as well as the larger architectures they may enable. This research was funded by the Office of the Director of National Intelligence (ODNI) and the Intelligence Advanced Research Projects Activity (IARPA) under Air Force Contract No. FA8721-05-C-0002. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of ODNI, IARPA, or the US Government.
On-chip coherent conversion of photonic quantum entanglement between different degrees of freedom.
Feng, Lan-Tian; Zhang, Ming; Zhou, Zhi-Yuan; Li, Ming; Xiong, Xiao; Yu, Le; Shi, Bao-Sen; Guo, Guo-Ping; Dai, Dao-Xin; Ren, Xi-Feng; Guo, Guang-Can
2016-01-01
In the quantum world, a single particle can have various degrees of freedom to encode quantum information. Controlling multiple degrees of freedom simultaneously is necessary to describe a particle fully and, therefore, to use it more efficiently. Here we introduce the transverse waveguide-mode degree of freedom to quantum photonic integrated circuits, and demonstrate the coherent conversion of a photonic quantum state between path, polarization and transverse waveguide-mode degrees of freedom on a single chip. The preservation of quantum coherence in these conversion processes is proven by single-photon and two-photon quantum interference using a fibre beam splitter or on-chip beam splitters. These results provide us with the ability to control and convert multiple degrees of freedom of photons for quantum photonic integrated circuit-based quantum information process. PMID:27321821
On-chip coherent conversion of photonic quantum entanglement between different degrees of freedom
Feng, Lan-Tian; Zhang, Ming; Zhou, Zhi-Yuan; Li, Ming; Xiong, Xiao; Yu, Le; Shi, Bao-Sen; Guo, Guo-Ping; Dai, Dao-Xin; Ren, Xi-Feng; Guo, Guang-Can
2016-01-01
In the quantum world, a single particle can have various degrees of freedom to encode quantum information. Controlling multiple degrees of freedom simultaneously is necessary to describe a particle fully and, therefore, to use it more efficiently. Here we introduce the transverse waveguide-mode degree of freedom to quantum photonic integrated circuits, and demonstrate the coherent conversion of a photonic quantum state between path, polarization and transverse waveguide-mode degrees of freedom on a single chip. The preservation of quantum coherence in these conversion processes is proven by single-photon and two-photon quantum interference using a fibre beam splitter or on-chip beam splitters. These results provide us with the ability to control and convert multiple degrees of freedom of photons for quantum photonic integrated circuit-based quantum information process. PMID:27321821
Microwave Photon Detector in Circuit QED
NASA Astrophysics Data System (ADS)
Garcia-Ripoll, Juan Jose; Romero, Guillermo; Solano, Enrique
2009-03-01
In this work we propose a design for a microwave photodetector based on elements from circuit QED such as the ones used in qubit designs. Our proposal consists on a microwave guide in which we embed circuital elements that can absorb photons and irreversibly change state. These incoherent absorption processes constitute the measurement itself. We first model this design using a general master equation for the propagating photons and the absorbing elements. We find that the detection efficiency for a single absorber is limited to 50%, and that this efficiency can be quickly increased by adding more elements with a moderate separation, obtaining 80% and 90% for two and three absorbers. Our abstract design has at least one possible implementation in which the absorbers are current biased Josephson junction. We demonstrate that the coupling between the guide and the junctions is strong enough, irrespectively of the microwave guide size, and derivate realistic parameters for high fidelity operation with current experiments. Patent pending No. 200802933, Oficina Espanola de Patentes y Marcas, 17/10/2008.
Advanced active quenching circuits for single-photon avalanche photodiodes
NASA Astrophysics Data System (ADS)
Stipčević, M.; Christensen, B. G.; Kwiat, P. G.; Gauthier, D. J.
2016-05-01
Commercial photon-counting modules, often based on actively quenched solid-state avalanche photodiode sensors, are used in wide variety of applications. Manufacturers characterize their detectors by specifying a small set of parameters, such as detection efficiency, dead time, dark counts rate, afterpulsing probability and single photon arrival time resolution (jitter), however they usually do not specify the conditions under which these parameters are constant or present a sufficient description. In this work, we present an in-depth analysis of the active quenching process and identify intrinsic limitations and engineering challenges. Based on that, we investigate the range of validity of the typical parameters used by two commercial detectors. We identify an additional set of imperfections that must be specified in order to sufficiently characterize the behavior of single-photon counting detectors in realistic applications. The additional imperfections include rate-dependence of the dead time, jitter, detection delay shift, and "twilighting." Also, the temporal distribution of afterpulsing and various artifacts of the electronics are important. We find that these additional non-ideal behaviors can lead to unexpected effects or strong deterioration of the system's performance. Specifically, we discuss implications of these new findings in a few applications in which single-photon detectors play a major role: the security of a quantum cryptographic protocol, the quality of single-photon-based random number generators and a few other applications. Finally, we describe an example of an optimized avalanche quenching circuit for a high-rate quantum key distribution system based on time-bin entangled photons.
Hybrid Toffoli gate on photons and quantum spins
NASA Astrophysics Data System (ADS)
Luo, Ming-Xing; Ma, Song-Ya; Chen, Xiu-Bo; Wang, Xiaojun
2015-11-01
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.
Hybrid Toffoli gate on photons and quantum spins
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.
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
Implementing quantum Fourier transform with integrated photonic devices
NASA Astrophysics Data System (ADS)
Tabia, Gelo Noel
2014-03-01
Many quantum algorithms that exhibit exponential speedup over their classical counterparts employ the quantum Fourier transform, which is used to solve interesting problems such as prime factorization. Meanwhile, nonclassical interference of single photons achieved on integrated platforms holds the promise of achieving large-scale quantum computation with multiport devices. An optical multiport device can be built to realize any quantum circuit as a sequence of unitary operations performed by beam splitters and phase shifters on path-encoded qudits. In this talk, I will present a recursive scheme for implementing quantum Fourier transform with a multimode interference photonic integrated circuit. Research at Perimeter Institute is supported by the Government of Canada through Industry Canada and by the Province of Ontario through the Ministry of Research and Innovation.
Demonstration of digital readout circuit for superconducting nanowire single photon detector.
Ortlepp, T; Hofherr, M; Fritzsch, L; Engert, S; Ilin, K; Rall, D; Toepfer, H; Meyer, H-G; Siegel, M
2011-09-12
We demonstrate the transfer of single photon triggered electrical pulses from a superconducting nanowire single photon detector (SNSPD) to a single flux quantum (SFQ) pulse. We describe design and test of a digital SFQ based SNSPD readout circuit and demonstrate its correct operation. Both circuits (SNSPD and SFQ) operate under the same cryogenic conditions and are directly connected by wire bonds. A future integration of the present multi-chip configuration seems feasible because both fabrication process and materials are very similar. In contrast to commonly used semiconductor amplifiers, SFQ circuits combine very low power dissipation (a few microwatts) with very high operation speed, thus enabling count-rates of several gigahertz. The SFQ interface circuit simplifies the SNSPD readout and enables large numbers of detectors for future compact multi-pixel systems with single photon counting resolution. The demonstrated circuit has great potential for scaling the present interface solution to 1,000 detectors by using a single SFQ chip. PMID:21935228
Strong Single-Photon Coupling in Superconducting Quantum Magnetomechanics
NASA Astrophysics Data System (ADS)
Via, Guillem; Kirchmair, Gerhard; Romero-Isart, Oriol
2015-04-01
We show that the inductive coupling between the quantum mechanical motion of a superconducting microcantilever and a flux-dependent microwave quantum circuit can attain the strong single-photon nanomechanical coupling regime with feasible experimental parameters. We propose to use a superconducting strip, which is in the Meissner state, at the tip of a cantilever. A pickup coil collects the flux generated by the sheet currents induced by an external quadrupole magnetic field centered at the strip location. The position-dependent magnetic response of the superconducting strip, enhanced by both diamagnetism and demagnetizing effects, leads to a strong magnetomechanical coupling to quantum circuits.
Engineering integrated photonics for heralded quantum gates.
Meany, Thomas; Biggerstaff, Devon N; Broome, Matthew A; Fedrizzi, Alessandro; Delanty, Michael; Steel, M J; Gilchrist, Alexei; Marshall, Graham D; White, Andrew G; Withford, Michael J
2016-01-01
Scaling up linear-optics quantum computing will require multi-photon gates which are compact, phase-stable, exhibit excellent quantum interference, and have success heralded by the detection of ancillary photons. We investigate the design, fabrication and characterisation of the optimal known gate scheme which meets these requirements: the Knill controlled-Z gate, implemented in integrated laser-written waveguide arrays. We show device performance to be less sensitive to phase variations in the circuit than to small deviations in the coupler reflectivity, which are expected given the tolerance values of the fabrication method. The mode fidelity is also shown to be less sensitive to reflectivity and phase errors than the process fidelity. Our best device achieves a fidelity of 0.931 ± 0.001 with the ideal 4 × 4 unitary circuit and a process fidelity of 0.680 ± 0.005 with the ideal computational-basis process. PMID:27282928
Engineering integrated photonics for heralded quantum gates
Meany, Thomas; Biggerstaff, Devon N.; Broome, Matthew A.; Fedrizzi, Alessandro; Delanty, Michael; Steel, M. J.; Gilchrist, Alexei; Marshall, Graham D.; White, Andrew G.; Withford, Michael J.
2016-01-01
Scaling up linear-optics quantum computing will require multi-photon gates which are compact, phase-stable, exhibit excellent quantum interference, and have success heralded by the detection of ancillary photons. We investigate the design, fabrication and characterisation of the optimal known gate scheme which meets these requirements: the Knill controlled-Z gate, implemented in integrated laser-written waveguide arrays. We show device performance to be less sensitive to phase variations in the circuit than to small deviations in the coupler reflectivity, which are expected given the tolerance values of the fabrication method. The mode fidelity is also shown to be less sensitive to reflectivity and phase errors than the process fidelity. Our best device achieves a fidelity of 0.931 ± 0.001 with the ideal 4 × 4 unitary circuit and a process fidelity of 0.680 ± 0.005 with the ideal computational-basis process. PMID:27282928
Engineering integrated photonics for heralded quantum gates
NASA Astrophysics Data System (ADS)
Meany, Thomas; Biggerstaff, Devon N.; Broome, Matthew A.; Fedrizzi, Alessandro; Delanty, Michael; Steel, M. J.; Gilchrist, Alexei; Marshall, Graham D.; White, Andrew G.; Withford, Michael J.
2016-06-01
Scaling up linear-optics quantum computing will require multi-photon gates which are compact, phase-stable, exhibit excellent quantum interference, and have success heralded by the detection of ancillary photons. We investigate the design, fabrication and characterisation of the optimal known gate scheme which meets these requirements: the Knill controlled-Z gate, implemented in integrated laser-written waveguide arrays. We show device performance to be less sensitive to phase variations in the circuit than to small deviations in the coupler reflectivity, which are expected given the tolerance values of the fabrication method. The mode fidelity is also shown to be less sensitive to reflectivity and phase errors than the process fidelity. Our best device achieves a fidelity of 0.931 ± 0.001 with the ideal 4 × 4 unitary circuit and a process fidelity of 0.680 ± 0.005 with the ideal computational-basis process.
Accelerating commutation circuits in quantum computer networks
NASA Astrophysics Data System (ADS)
Jiang, Min; Huang, Xu; Chen, Xiaoping; Zhang, Zeng-ke
2012-12-01
In a high speed and packet-switched quantum computer network, a packet routing delay often leads to traffic jams, becoming a severe bottleneck for speeding up the transmission rate. Based on the delayed commutation circuit proposed in Phys. Rev. Lett. 97, 110502 (2006), we present an improved scheme for accelerating network transmission. For two more realistic scenarios, we utilize the characteristic of a quantum state to simultaneously implement a data switch and transmission that makes it possible to reduce the packet delay and route a qubit packet even before its address is determined. This circuit is further extended to the quantum network for the transmission of the unknown quantum information. The analysis demonstrates that quantum communication technology can considerably reduce the processing delay time and build faster and more efficient packet-switched networks.
Efficient Toffoli Gate in Circuit Quantum Electrodynamics
NASA Astrophysics Data System (ADS)
Reed, Matthew; Dicarlo, Leonardo; Sun, Luyan; Frunzio, Luigi; Schoelkopf, Robert
2011-03-01
The fidelity of quantum gates in circuit quantum electrodynamics is typically limited by qubit decoherence. As such, significant improvements can be realized by shortening gate duration. The three-qubit Toffoli gate, also called the controlled-controlled NOT, is an important operation in basic quantum error correction. We report a scheme for a Toffoli gate that exploits interactions with non-computational excited states of transmon qubits which can be executed faster than an equivalent construction using one- and two-qubit gates. The application of this gate to efficient measurement-free quantum error correction will be discussed. Research supported by NSF, NSA, and ARO.
Quantum RLC circuits: Charge discreteness and resonance
NASA Astrophysics Data System (ADS)
Utreras-Díaz, Constantino A.
2008-10-01
In a recent article [C.A. Utreras-Díaz, Phys. Lett. A 372 (2008) 5059], we have advanced a semiclassical theory of quantum circuits with discrete charge and electrical resistance. In this work, we present a few elementary applications of this theory. For the zero resistance inductive circuit, we obtain the Stark ladder energies in yet another way; for the circuit driven by a combination d.c. plus a.c. electromotive force (emf) we generalize earlier results by Chandía et al. [K. Chandía, J.C. Flores, E. Lazo, Phys. Lett. A 359 (2006) 693]. As a second application, we investigate the effect of electrical resistance and charge discreteness, in the resonance conditions of a series RLC quantum circuit.
Electron-photon coupling in mesoscopic quantum electrodynamics
NASA Astrophysics Data System (ADS)
Cottet, A.; Kontos, T.; Douçot, B.
2015-05-01
Understanding the interaction between cavity photons and electronic nanocircuits is crucial for the development of mesoscopic quantum electrodynamics (QED). One has to combine ingredients from atomic cavity QED, such as orbital degrees of freedom, with tunneling physics and strong cavity field inhomogeneities, specific to superconducting circuit QED. It is therefore necessary to introduce a formalism which bridges between these two domains. We develop a general method based on a photonic pseudopotential to describe the electric coupling between electrons in a nanocircuit and cavity photons. In this picture, photons can induce simultaneously orbital energy shifts, tunneling, and local orbital transitions. We study in detail the elementary example of a single quantum dot with a single normal metal reservoir, coupled to a cavity. Photon-induced tunneling terms lead to a nonuniversal relation between the cavity frequency pull and the damping pull. Our formalism can also be applied to multiple quantum dot circuits, molecular circuits, quantum point contacts, metallic tunnel junctions, and superconducting nanostructures enclosing Andreev bound states or Majorana bound states, for instance.
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. PMID:23938640
Quantum-entangled photon interferometry
NASA Astrophysics Data System (ADS)
Richards, Roger K.
2004-08-01
A two-color quantum-entangled photon source is used to produce fourth-order interference. Because the period of the interference is produced by the frequency difference of the entangled photons, problems associated with counting fringes can be avoided. This also permits measurements at a virtual wavelength, which can prevent problems associated with transmission or absorption when such a longer wavelength may be needed. The interference wavelength can be varied with a geometry change in the beam path without any change in the source wavelength. The entangled photons are produced using an argon ion laser at 351 nanometers and a type I BBO crystal. The interference is detected in coincidence using four photomultiplier tubes.
Experimental Quantum Optics with Photons
NASA Astrophysics Data System (ADS)
Wu, Ling-An
2005-10-01
Our group is engaged primarily in experimental quantum optics and related research involving single photon detection that may have future applications. There are six graduate students involved, of whom three are women. We have recently completed the first successful demonstration of correlated two-photon imaging and sub-wavelength interference with true thermal light from a hollow cathode lamp. The object was a pair of pinholes, and the corresponding thin lens equation was well satisfied. Although the visibility is substantially lower than in the case of entangled photons, it is conceivable that if the background could be removed by some means (e.g., digitally), there could be many applications for correlated imaging with thermal light. We have also built a quantum key distribution system based on two polarization beam splitters that cancel out the phase modulator's polarization dependence. A high key generation rate has been obtained for the first time at 1310 nm transmitted over a 25-km-long fiber, with a fringe visibility of 99.4%. A sifted key rate of about 0.6 kbits/s and quantum bit error rate of about 0.5% have been obtained.
Entanglement distillation in circuit quantum electrodynamics
NASA Astrophysics Data System (ADS)
Oppliger, Markus; Heinsoo, Johannes; Salathe, Yves; Potocnik, Anton; Mondal, Mintu; Wallraff, Andreas; Paraoanu, Gheorghe Sorin
Entanglement is an essential resource for quantum information processing, such as quantum error correction, quantum teleportation and quantum communication. Such algorithms perform optimally with maximally entangled states. In practice entangled quantum states are very fragile due to a wide range of decoherence mechanisms. When two parties share degraded entangled states they are still able to generate an entangled state with higher fidelity using local operations and classical communication. This process is commonly referred to as entanglement distillation. Here we demonstrate distillation of highly entangled Bell states from two copies of less entangled states on a four transmon qubit device realized in the circuit-QED architecture. We characterize the output state for different degrees of entanglement at the input with quantum state tomography. A clear improvement of the entanglement measures is observed at the output.
Universal Quantum Cloning Machine in Circuit Quantum Electrodynamics
NASA Astrophysics Data System (ADS)
Lv, Dan-Dan; Lu, Hong; Yu, Ya-Fei; Feng, Xun-Li; Zhang, Zhi-Ming
2010-02-01
We propose a scheme for realizing the 1 → 2 universal quantum cloning machine (UQCM) with superconducting quantum interference device (SQUID) qubits in circuit quantum electrodynamics (circuit QED). In this scheme, in order to implement UQCM, we only need phase shift gate operation on SQUID qubits and the Raman transitions. The cavity number we need is only one. Thus our scheme is simple and has advantages in the experimental realization. Furthermore, both the cavity and the SQUID qubits are virtually excited, so the decoherence can be neglected.
One-way quantum computation with circuit quantum electrodynamics
Wu Chunwang; Han Yang; Chen Pingxing; Li Chengzu; Zhong Xiaojun
2010-03-15
In this Brief Report, we propose a potential scheme to implement one-way quantum computation with circuit quantum electrodynamics (QED). Large cluster states of charge qubits can be generated in just one step with a superconducting transmission line resonator (TLR) playing the role of a dispersive coupler. A single-qubit measurement in the arbitrary basis can be implemented using a single electron transistor with the help of one-qubit gates. By examining the main decoherence sources, we show that circuit QED is a promising architecture for one-way quantum computation.
Quantum fully homomorphic encryption scheme based on universal quantum circuit
NASA Astrophysics Data System (ADS)
Liang, Min
2015-08-01
Fully homomorphic encryption enables arbitrary computation on encrypted data without decrypting the data. Here it is studied in the context of quantum information processing. Based on universal quantum circuit, we present a quantum fully homomorphic encryption (QFHE) scheme, which permits arbitrary quantum transformation on any encrypted data. The QFHE scheme is proved to be perfectly secure. In the scheme, the decryption key is different from the encryption key; however, the encryption key cannot be revealed. Moreover, the evaluation algorithm of the scheme is independent of the encryption key, so it is suitable for delegated quantum computing between two parties.
Computational quantum-classical boundary of noisy commuting quantum circuits
Fujii, Keisuke; Tamate, Shuhei
2016-01-01
It is often said that the transition from quantum to classical worlds is caused by decoherence originated from an interaction between a system of interest and its surrounding environment. Here we establish a computational quantum-classical boundary from the viewpoint of classical simulatability of a quantum system under decoherence. Specifically, we consider commuting quantum circuits being subject to decoherence. Or equivalently, we can regard them as measurement-based quantum computation on decohered weighted graph states. To show intractability of classical simulation in the quantum side, we utilize the postselection argument and crucially strengthen it by taking noise effect into account. Classical simulatability in the classical side is also shown constructively by using both separable criteria in a projected-entangled-pair-state picture and the Gottesman-Knill theorem for mixed state Clifford circuits. We found that when each qubit is subject to a single-qubit complete-positive-trace-preserving noise, the computational quantum-classical boundary is sharply given by the noise rate required for the distillability of a magic state. The obtained quantum-classical boundary of noisy quantum dynamics reveals a complexity landscape of controlled quantum systems. This paves a way to an experimentally feasible verification of quantum mechanics in a high complexity limit beyond classically simulatable region. PMID:27189039
Computational quantum-classical boundary of noisy commuting quantum circuits
NASA Astrophysics Data System (ADS)
Fujii, Keisuke; Tamate, Shuhei
2016-05-01
It is often said that the transition from quantum to classical worlds is caused by decoherence originated from an interaction between a system of interest and its surrounding environment. Here we establish a computational quantum-classical boundary from the viewpoint of classical simulatability of a quantum system under decoherence. Specifically, we consider commuting quantum circuits being subject to decoherence. Or equivalently, we can regard them as measurement-based quantum computation on decohered weighted graph states. To show intractability of classical simulation in the quantum side, we utilize the postselection argument and crucially strengthen it by taking noise effect into account. Classical simulatability in the classical side is also shown constructively by using both separable criteria in a projected-entangled-pair-state picture and the Gottesman-Knill theorem for mixed state Clifford circuits. We found that when each qubit is subject to a single-qubit complete-positive-trace-preserving noise, the computational quantum-classical boundary is sharply given by the noise rate required for the distillability of a magic state. The obtained quantum-classical boundary of noisy quantum dynamics reveals a complexity landscape of controlled quantum systems. This paves a way to an experimentally feasible verification of quantum mechanics in a high complexity limit beyond classically simulatable region.
Computational quantum-classical boundary of noisy commuting quantum circuits.
Fujii, Keisuke; Tamate, Shuhei
2016-01-01
It is often said that the transition from quantum to classical worlds is caused by decoherence originated from an interaction between a system of interest and its surrounding environment. Here we establish a computational quantum-classical boundary from the viewpoint of classical simulatability of a quantum system under decoherence. Specifically, we consider commuting quantum circuits being subject to decoherence. Or equivalently, we can regard them as measurement-based quantum computation on decohered weighted graph states. To show intractability of classical simulation in the quantum side, we utilize the postselection argument and crucially strengthen it by taking noise effect into account. Classical simulatability in the classical side is also shown constructively by using both separable criteria in a projected-entangled-pair-state picture and the Gottesman-Knill theorem for mixed state Clifford circuits. We found that when each qubit is subject to a single-qubit complete-positive-trace-preserving noise, the computational quantum-classical boundary is sharply given by the noise rate required for the distillability of a magic state. The obtained quantum-classical boundary of noisy quantum dynamics reveals a complexity landscape of controlled quantum systems. This paves a way to an experimentally feasible verification of quantum mechanics in a high complexity limit beyond classically simulatable region. PMID:27189039
Quantum entanglement in circuit QED
Milburn, G. J.; Meaney, Charles
2008-11-07
We show that the ground state of a very strongly coupled two level system based on a superconducting island and a microwave cavity field can undergo a morphological change as the coupling strength is increased. This looks like a quantum phase transition and is characterized by the appearance of entanglement between the cavity field and the two level system.
Photonic Quantum Logic with Narrowband Light from Single Atoms
NASA Astrophysics Data System (ADS)
Rubenok, Allison; Holleczek, Annemarie; Barter, Oliver; Dilley, Jerome; Nisbet-Jones, Peter B. R.; Langfahl-Klabes, Gunnar; Kuhn, Axel; Sparrow, Chris; Marshall, Graham D.; O'Brien, Jeremy L.; Poulios, Konstantinos; Matthews, Jonathan C. F.
Atom-cavity sources of narrowband photons are a promising candidate for the future development of quantum technologies. Likewise, integrated photonic circuits have established themselves as a fore-running contender in quantum computing, security, and communication. Here we report on recent achievements to interface these two technologies: Atom-cavity sources coupled to integrated photonic circuits. Using narrow linewidth photons emitted from a single 87 Rb atom strongly coupled to a high-finesse cavity we demonstrate the successful operation of an integrated control-not gate. Furthermore, we are able to verify the generation of post-selected entanglement upon successful operation of the gate. We are able to see non-classical correlations in detection events that are up to three orders of magnitude farther apart than the time needed for light to travel across the chip. Our hybrid approach will facilitate the future development of technologies that benefit from the advantages of both integrated quantum circuits and atom-cavity photon sources. Now at: National Physics Laboratory.
Two-resonator circuit quantum electrodynamics: A superconducting quantum switch
NASA Astrophysics Data System (ADS)
Mariantoni, Matteo; Deppe, Frank; Marx, A.; Gross, R.; Wilhelm, F. K.; Solano, E.
2008-09-01
We introduce a systematic formalism for two-resonator circuit QED, where two on-chip microwave resonators are simultaneously coupled to one superconducting qubit. Within this framework, we demonstrate that the qubit can function as a quantum switch between the two resonators, which are assumed to be originally independent. In this three-circuit network, the qubit mediates a geometric second-order circuit interaction between the otherwise decoupled resonators. In the dispersive regime, it also gives rise to a dynamic second-order perturbative interaction. The geometric and dynamic coupling strengths can be tuned to be equal, thus permitting to switch on and off the interaction between the two resonators via a qubit population inversion or a shifting of the qubit operation point. We also show that our quantum switch represents a flexible architecture for the manipulation and generation of nonclassical microwave field states as well as the creation of controlled multipartite entanglement in circuit QED. In addition, we clarify the role played by the geometric interaction, which constitutes a fundamental property characteristic of superconducting quantum circuits without a counterpart in quantum-optical systems. We develop a detailed theory of the geometric second-order coupling by means of circuit transformations for superconducting charge and flux qubits. Furthermore, we show the robustness of the quantum switch operation with respect to decoherence mechanisms. Finally, we propose a realistic design for a two-resonator circuit QED setup based on a flux qubit and estimate all the related parameters. In this manner, we show that this setup can be used to implement a superconducting quantum switch with available technology.
Quantum state engineering with circuit electromechanical three-body interactions.
Abdi, Mehdi; Pernpeintner, Matthias; Gross, Rudolf; Huebl, Hans; Hartmann, Michael J
2015-05-01
We propose a hybrid system with quantum mechanical three-body interactions between photons, phonons, and qubit excitations. These interactions take place in a circuit quantum electrodynamical architecture with a superconducting microwave resonator coupled to a transmon qubit whose shunt capacitance is free to mechanically oscillate. We show that this system design features a three-mode polariton-mechanical mode and a nonlinear transmon-mechanical mode interaction in the strong coupling regime. Together with the strong resonator-transmon interaction, these properties provide intriguing opportunities for manipulations of this hybrid quantum system. We show, in particular, the feasibility of cooling the mechanical motion down to its ground state and preparing various nonclassical states including mechanical Fock and cat states and hybrid tripartite entangled states. PMID:25978232
Quantum State Engineering with Circuit Electromechanical Three-Body Interactions
NASA Astrophysics Data System (ADS)
Abdi, Mehdi; Pernpeintner, Matthias; Gross, Rudolf; Huebl, Hans; Hartmann, Michael J.
2015-05-01
We propose a hybrid system with quantum mechanical three-body interactions between photons, phonons, and qubit excitations. These interactions take place in a circuit quantum electrodynamical architecture with a superconducting microwave resonator coupled to a transmon qubit whose shunt capacitance is free to mechanically oscillate. We show that this system design features a three-mode polariton-mechanical mode and a nonlinear transmon-mechanical mode interaction in the strong coupling regime. Together with the strong resonator-transmon interaction, these properties provide intriguing opportunities for manipulations of this hybrid quantum system. We show, in particular, the feasibility of cooling the mechanical motion down to its ground state and preparing various nonclassical states including mechanical Fock and cat states and hybrid tripartite entangled states.
Quantum-limited Amplification via Dissipation in Superconducting Circuits
NASA Astrophysics Data System (ADS)
Metelmann, A.; Clerk, A. A.
2015-03-01
The development of parametric amplifiers based on superconducting circuits has led to an impressive improvement in the precision and sensitivity of measurements in the quantum regime. However, standard cavity-based parametric amplifiers suffer from a fixed gain-bandwidth product. Moreover they are reciprocal devices, i.e., they amplify in both directions, leading to the requirement of additional noisy elements as circulators in the measurement chain. In our recent work we discussed a phase-insensitive quantum amplifier which utilizes dissipative interactions in a parametrically-coupled three-mode bosonic system. The use of dissipative interactions provides a fundamental advantage over standard cavity-based parametric amplifiers: large photon number gains are possible with quantum-limited added noise, with no limitation on the gain-bandwidth product. In this talk we present how this can be extended to phase-sensitive amplifiers and discuss the possibilities of making the amplifier directional.
Pernice, W.H.P.; Schuck, C.; Minaeva, O.; Li, M.; Goltsman, G.N.; Sergienko, A.V.; Tang, H.X.
2012-01-01
Ultrafast, high-efficiency single-photon detectors are among the most sought-after elements in modern quantum optics and quantum communication. However, imperfect modal matching and finite photon absorption rates have usually limited their maximum attainable detection efficiency. Here we demonstrate superconducting nanowire detectors atop nanophotonic waveguides, which enable a drastic increase of the absorption length for incoming photons. This allows us to achieve high on-chip single-photon detection efficiency up to 91% at telecom wavelengths, repeatable across several fabricated chips. We also observe remarkably low dark count rates without significant compromise of the on-chip detection efficiency. The detectors are fully embedded in scalable silicon photonic circuits and provide ultrashort timing jitter of 18 ps. Exploiting this high temporal resolution, we demonstrate ballistic photon transport in silicon ring resonators. Our direct implementation of a high-performance single-photon detector on chip overcomes a major barrier in integrated quantum photonics. PMID:23271658
Parallel Quantum Circuit in a Tunnel Junction
NASA Astrophysics Data System (ADS)
Faizy Namarvar, Omid; Dridi, Ghassen; Joachim, Christian; GNS theory group Team
In between 2 metallic nanopads, adding identical and independent electron transfer paths in parallel increases the electronic effective coupling between the 2 nanopads through the quantum circuit defined by those paths. Measuring this increase of effective coupling using the tunnelling current intensity can lead for example for 2 paths in parallel to the now standard G =G1 +G2 + 2√{G1 .G2 } conductance superposition law (1). This is only valid for the tunnelling regime (2). For large electronic coupling to the nanopads (or at resonance), G can saturate and even decay as a function of the number of parallel paths added in the quantum circuit (3). We provide here the explanation of this phenomenon: the measurement of the effective Rabi oscillation frequency using the current intensity is constrained by the normalization principle of quantum mechanics. This limits the quantum conductance G for example to go when there is only one channel per metallic nanopads. This ef fect has important consequences for the design of Boolean logic gates at the atomic scale using atomic scale or intramolecular circuits. References: This has the financial support by European PAMS project.
In-plane emission of indistinguishable photons generated by an integrated quantum emitter
Kalliakos, Sokratis Bennett, Anthony J.; Ward, Martin B.; Ellis, David J. P.; Skiba-Szymanska, Joanna; Shields, Andrew J.; Brody, Yarden; Schwagmann, Andre; Farrer, Ian; Griffiths, Jonathan P.; Jones, Geb A. C.; Ritchie, David A.
2014-06-02
We demonstrate the emission of indistinguishable photons along a semiconductor chip originating from carrier recombination in an InAs quantum dot. The emitter is integrated in the waveguiding region of a photonic crystal structure, allowing for on-chip light propagation. We perform a Hong-Ou-Mandel-type of experiment with photons collected from the exit of the waveguide, and we observe two-photon interference under continuous wave excitation. Our results pave the way for the integration of quantum emitters in advanced photonic quantum circuits.
Superconducting circuit probe for analog quantum simulators
NASA Astrophysics Data System (ADS)
Du, Liang-Hui; You, J. Q.; Tian, Lin
2015-07-01
Analog quantum simulators can be used to study quantum correlation in novel many-body systems by emulating the Hamiltonian of these systems. One essential question in quantum simulation is to probe the properties of an emulated many-body system. Here we present a circuit QED scheme for probing such properties by measuring the spectrum of a superconducting resonator coupled to a quantum simulator. We first study a general framework of this approach and show that the spectrum of the resonator is directly related to the correlation function of the coupling operator between the resonator and the simulator. We then apply this scheme to a simulator of the transverse field Ising model implemented with superconducting qubits, where the resonance peaks in the resonator spectrum correspond to the frequencies of the elementary excitations. The effects of resonator damping, qubit decoherence, and resonator backaction are also discussed. This setup can be used to probe a broad range of many-body models.
Towards quantum thermodynamics in electronic circuits
NASA Astrophysics Data System (ADS)
Pekola, Jukka P.
2015-02-01
Electronic circuits operating at sub-kelvin temperatures are attractive candidates for studying classical and quantum thermodynamics: their temperature can be controlled and measured locally with exquisite precision, and they allow experiments with large statistical samples. The availability and rapid development of devices such as quantum dots, single-electron boxes and superconducting qubits only enhance their appeal. But although these systems provide fertile ground for studying heat transport, entropy production and work in the context of quantum mechanics, the field remains in its infancy experimentally. Here, we review some recent experiments on quantum heat transport, fluctuation relations and implementations of Maxwell's demon, revealing the rich physics yet to be fully probed in these systems.
Quantum simulations of relativistic quantum physics in circuit QED
NASA Astrophysics Data System (ADS)
Pedernales, J. S.; Di Candia, R.; Ballester, D.; Solano, E.
2013-05-01
We present a scheme for simulating relativistic quantum physics in circuit quantum electrodynamics. By using three classical microwave drives, we show that a superconducting qubit strongly coupled to a resonator field mode can be used to simulate the dynamics of the Dirac equation and Klein paradox in all regimes. Using the same setup we also propose the implementation of the Foldy-Wouthuysen canonical transformation, after which the time derivative of the position operator becomes a constant of the motion.
Quantum electrodynamics near a photonic band-gap
NASA Astrophysics Data System (ADS)
Liu, Yanbing; Houck, Andrew
Quantum electrodynamics predicts the localization of light around an atom in photonic band-gap (PBG) medium or photonic crystal. Here we report the first experimental realization of the strong coupling between a single artificial atom and an one dimensional PBG medium using superconducting circuits. In the photonic transport measurement, we observe an anomalous Lamb shift and a large band-edge avoided crossing when the artificial atom frequency is tuned across the band-edge. The persistent peak within the band-gap indicates the single photon bound state. Furthermore, we study the resonance fluorescence of this bound state, again demonstrating the breakdown of the Born-Markov approximation near the band-edge. This novel architecture can be directly generalized to study many-body quantum electrodynamics and to construct more complicated spin chain models.
Inelastic microwave photon scattering off a quantum impurity in a Josephson-junction array.
Goldstein, Moshe; Devoret, Michel H; Houzet, Manuel; Glazman, Leonid I
2013-01-01
Quantum fluctuations in an anharmonic superconducting circuit enable frequency conversion of individual incoming photons. This effect, linear in the photon beam intensity, leads to ramifications for the standard input-output circuit theory. We consider an extreme case of anharmonicity in which photons scatter off a small set of weak links within a Josephson junction array. We show that this quantum impurity displays Kondo physics and evaluate the elastic and inelastic photon scattering cross sections. These cross sections reveal many-body properties of the Kondo problem that are hard to access in its traditional fermionic version. PMID:23383827
Ultrafast single photon emitting quantum photonic structures based on a nano-obelisk
Kim, Je-Hyung; Ko, Young-Ho; Gong, Su-Hyun; Ko, Suk-Min; Cho, Yong-Hoon
2013-01-01
A key issue in a single photon source is fast and efficient generation of a single photon flux with high light extraction efficiency. Significant progress toward high-efficiency single photon sources has been demonstrated by semiconductor quantum dots, especially using narrow bandgap materials. Meanwhile, there are many obstacles, which restrict the use of wide bandgap semiconductor quantum dots as practical single photon sources in ultraviolet-visible region, despite offering free space communication and miniaturized quantum information circuits. Here we demonstrate a single InGaN quantum dot embedded in an obelisk-shaped GaN nanostructure. The nano-obelisk plays an important role in eliminating dislocations, increasing light extraction, and minimizing a built-in electric field. Based on the nano-obelisks, we observed nonconventional narrow quantum dot emission and positive biexciton binding energy, which are signatures of negligible built-in field in single InGaN quantum dots. This results in efficient and ultrafast single photon generation in the violet color region. PMID:23828558
Teleporting photonic qudits using multimode quantum scissors.
Goyal, Sandeep K; Konrad, Thomas
2013-01-01
Teleportation plays an important role in the communication of quantum information between the nodes of a quantum network and is viewed as an essential ingredient for long-distance Quantum Cryptography. We describe a method to teleport the quantum information carried by a photon in a superposition of a number d of light modes (a "qudit") by the help of d additional photons based on transcription. A qudit encoded into a single excitation of d light modes (in our case Laguerre-Gauss modes which carry orbital angular momentum) is transcribed to d single-rail photonic qubits, which are spatially separated. Each single-rail qubit consists of a superposition of vacuum and a single photon in each one of the modes. After successful teleportation of each of the d single-rail qubits by means of "quantum scissors" they are converted back into a qudit carried by a single photon which completes the teleportation scheme. PMID:24352610
Teleporting photonic qudits using multimode quantum scissors
NASA Astrophysics Data System (ADS)
Goyal, Sandeep K.; Konrad, Thomas
2013-12-01
Teleportation plays an important role in the communication of quantum information between the nodes of a quantum network and is viewed as an essential ingredient for long-distance Quantum Cryptography. We describe a method to teleport the quantum information carried by a photon in a superposition of a number d of light modes (a ``qudit'') by the help of d additional photons based on transcription. A qudit encoded into a single excitation of d light modes (in our case Laguerre-Gauss modes which carry orbital angular momentum) is transcribed to d single-rail photonic qubits, which are spatially separated. Each single-rail qubit consists of a superposition of vacuum and a single photon in each one of the modes. After successful teleportation of each of the d single-rail qubits by means of ``quantum scissors'' they are converted back into a qudit carried by a single photon which completes the teleportation scheme.
Quantum memory with millisecond coherence in circuit QED
NASA Astrophysics Data System (ADS)
Reagor, Matthew; Pfaff, Wolfgang; Axline, Christopher; Heeres, Reinier W.; Ofek, Nissim; Sliwa, Katrina; Holland, Eric; Wang, Chen; Blumoff, Jacob; Chou, Kevin; Hatridge, Michael J.; Frunzio, Luigi; Devoret, Michel H.; Jiang, Liang; Schoelkopf, Robert J.
2016-07-01
Significant advances in coherence render superconducting quantum circuits a viable platform for fault-tolerant quantum computing. To further extend capabilities, highly coherent quantum systems could act as quantum memories for these circuits. A useful quantum memory must be rapidly addressable by Josephson-junction-based artificial atoms, while maintaining superior coherence. We demonstrate a superconducting microwave cavity architecture that is highly robust against major sources of loss that are encountered in the engineering of circuit QED systems. The architecture allows for storage of quantum superpositions in a resonator on the millisecond scale, while strong coupling between the resonator and a transmon qubit enables control, encoding, and readout at MHz rates. This extends the maximum available coherence time attainable in superconducting circuits by almost an order of magnitude compared to earlier hardware. Our design is an ideal platform for studying coherent quantum optics and marks an important step towards hardware-efficient quantum computing in Josephson-junction-based quantum circuits.
Organic printed photonics: From microring lasers to integrated circuits.
Zhang, Chuang; Zou, Chang-Ling; Zhao, Yan; Dong, Chun-Hua; Wei, Cong; Wang, Hanlin; Liu, Yunqi; Guo, Guang-Can; Yao, Jiannian; Zhao, Yong Sheng
2015-09-01
A photonic integrated circuit (PIC) is the optical analogy of an electronic loop in which photons are signal carriers with high transport speed and parallel processing capability. Besides the most frequently demonstrated silicon-based circuits, PICs require a variety of materials for light generation, processing, modulation, and detection. With their diversity and flexibility, organic molecular materials provide an alternative platform for photonics; however, the versatile fabrication of organic integrated circuits with the desired photonic performance remains a big challenge. The rapid development of flexible electronics has shown that a solution printing technique has considerable potential for the large-scale fabrication and integration of microsized/nanosized devices. We propose the idea of soft photonics and demonstrate the function-directed fabrication of high-quality organic photonic devices and circuits. We prepared size-tunable and reproducible polymer microring resonators on a wafer-scale transparent and flexible chip using a solution printing technique. The printed optical resonator showed a quality (Q) factor higher than 4 × 10(5), which is comparable to that of silicon-based resonators. The high material compatibility of this printed photonic chip enabled us to realize low-threshold microlasers by doping organic functional molecules into a typical photonic device. On an identical chip, this construction strategy allowed us to design a complex assembly of one-dimensional waveguide and resonator components for light signal filtering and optical storage toward the large-scale on-chip integration of microscopic photonic units. Thus, we have developed a scheme for soft photonic integration that may motivate further studies on organic photonic materials and devices. PMID:26601256
Organic printed photonics: From microring lasers to integrated circuits
Zhang, Chuang; Zou, Chang-Ling; Zhao, Yan; Dong, Chun-Hua; Wei, Cong; Wang, Hanlin; Liu, Yunqi; Guo, Guang-Can; Yao, Jiannian; Zhao, Yong Sheng
2015-01-01
A photonic integrated circuit (PIC) is the optical analogy of an electronic loop in which photons are signal carriers with high transport speed and parallel processing capability. Besides the most frequently demonstrated silicon-based circuits, PICs require a variety of materials for light generation, processing, modulation, and detection. With their diversity and flexibility, organic molecular materials provide an alternative platform for photonics; however, the versatile fabrication of organic integrated circuits with the desired photonic performance remains a big challenge. The rapid development of flexible electronics has shown that a solution printing technique has considerable potential for the large-scale fabrication and integration of microsized/nanosized devices. We propose the idea of soft photonics and demonstrate the function-directed fabrication of high-quality organic photonic devices and circuits. We prepared size-tunable and reproducible polymer microring resonators on a wafer-scale transparent and flexible chip using a solution printing technique. The printed optical resonator showed a quality (Q) factor higher than 4 × 105, which is comparable to that of silicon-based resonators. The high material compatibility of this printed photonic chip enabled us to realize low-threshold microlasers by doping organic functional molecules into a typical photonic device. On an identical chip, this construction strategy allowed us to design a complex assembly of one-dimensional waveguide and resonator components for light signal filtering and optical storage toward the large-scale on-chip integration of microscopic photonic units. Thus, we have developed a scheme for soft photonic integration that may motivate further studies on organic photonic materials and devices. PMID:26601256
Photonic qubits for remote quantum information processing
NASA Astrophysics Data System (ADS)
Maunz, P.; Olmschenk, S.; Hayes, D.; Matsukevich, D. N.; Duan, L.-M.; Monroe, C.
2009-05-01
Quantum information processing between remote quantum memories relies on a fast and faithful quantum channel. Recent experiments employed both, the photonic polarization and frequency qubits, in order to entangle remote atoms [1, 2], to teleport quantum information [3] and to operate a quantum gate between distant atoms. Here, we compare the dierent schemes used in these experiments and analyze the advantages of the dierent choices of atomic and photonic qubits and their coherence properties. [4pt] [1] D. L. Moehring et al. Nature 449, 68 (2007).[0pt] [2] D. N. Matsukevich et al. Phys. Rev. Lett. 100, 150404 2008).[0pt] [3] S. Olmschenk et al. Science, 323, 486 (2009).
Multimode circuit optomechanics near the quantum limit
Massel, Francesco; Cho, Sung Un; Pirkkalainen, Juha-Matti; Hakonen, Pertti J.; Heikkilä, Tero T.; Sillanpää, Mika A.
2012-01-01
The coupling of distinct systems underlies nearly all physical phenomena. A basic instance is that of interacting harmonic oscillators, giving rise to, for example, the phonon eigenmodes in a lattice. Of particular importance are the interactions in hybrid quantum systems, which can combine the benefits of each part in quantum technologies. Here we investigate a hybrid optomechanical system having three degrees of freedom, consisting of a microwave cavity and two micromechanical beams with closely spaced frequencies around 32 MHz and no direct interaction. We record the first evidence of tripartite optomechanical mixing, implying that the eigenmodes are combinations of one photonic and two phononic modes. We identify an asymmetric dark mode having a long lifetime. Simultaneously, we operate the nearly macroscopic mechanical modes close to the motional quantum ground state, down to 1.8 thermal quanta, achieved by back-action cooling. These results constitute an important advance towards engineering of entangled motional states. PMID:22871806
Waveguide circuits in three-dimensional photonic crystals
Biswas, Rana; Christensen, C.; Muehlmeier, J.; Tuttle, G.; Ho, K.-M.
2008-04-07
Waveguide circuits in three-dimensional photonic crystals with complete photonic band gaps are simulated with finite difference time domain (FDTD) simulations, and compared with measurements on microwave scale photonic crystals. The transmission through waveguide bends critically depends on the photonic crystal architecture in the bend region. We have found experimentally and theoretically, a new waveguide bend configuration consisting of overlapping rods in the bend region, that performs better than the simple waveguide bend of terminated rods, especially in the higher frequency portion of the band. Efficient beam splitters with this junction geometry are also simulated.
Photonic crystals--a step towards integrated circuits for photonics.
Thylén, Lars; Qiu, Min; Anand, Srinivasan
2004-09-20
The field of photonic crystals has, over the past few years, received dramatically increased attention. Photonic crystals are artificially engineered structures that exhibit a periodic variation in one, two, or three dimensions of the dielectric constant, with a period of the order of the pertinent light wavelength. Such structures in three dimensions should exhibit properties similar to solid-state electronic crystals, such as bandgaps, in other words wavelength regions where light cannot propagate in any direction. By introducing defects into the periodic arrangement, the photonic crystals exhibit properties analogous to those of solid-state crystals. The basic feature of a photonic bandgap was indeed experimentally demonstrated in the beginning of the 1990s, and sparked a large interest in, and in many ways revitalized, photonics research. There are several reasons for this attention. One is that photonic crystals, in their own right, offer a proliferation of challenging research tasks, involving a multitude of disciplines, such as electromagnetic theory, nanofabrication, semi-conductor technology, materials science, biotechnology, to name a few. Another reason is given by the somewhat more down-to-earth expectations that photonics crystals will create unique opportunities for novel devices and applications, and contribute to solving some of the issues that have plagued photonics such as large physical sizes, comparatively low functionality, and high costs. Herein, we will treat some basics of photonic crystal structures and discuss the state-of-the-art in fabrication as well give some examples of devices with unique properties, due to the use of photonic crystals. We will also point out some of the problems that still remain to be solved, and give a view on where photonic crystals currently stand. PMID:15499844
High-speed bridge circuit for InGaAs avalanche photodiode single-photon detector
NASA Astrophysics Data System (ADS)
Hashimoto, Hirofumi; Tomita, Akihisa; Okamoto, Atsushi
2014-02-01
Because of low power consumption and small footprint, avalanche photodiodes (APD) have been commonly applied to photon detection. Recently, high speed quantum communication has been demonstrated for high bit-rate quantum key distribution. For the high speed quantum communication, photon detectors should operate at GHz-clock frequencies. We propose balanced detection circuits for GHz-clock operation of InGaAs-APD photon detectors. The balanced single photon detector operates with sinusoidal wave gating. The sinusoidal wave appearing in the output is removed by the subtraction from APD signal without sharp band-elimination filters. Omission of the sharp filters removes the constraint on the operating frequency of the single photon detector. We present two designs, one works with two identical APDs, the other with one APD and a low-pass filter. The sinusoidal gating enables to eliminate the gating noise even with the simple configuration of the latter design. We demonstrated the balanced single photon detector operating with 1.020GHz clock at 233 K, 193 K, and 186.5 K. The dark count probability was 4.0 x 10-4 counts/pulse with the quantum efficiency of 10% at 233K, and 1.6 x 10-4 counts/pulse at 186.5 K. These results were obtained with easily available APDs (NR8300FP-C.C, RENESASS) originally developed for optical time-domain reflectmeters.
Testing foundations of quantum mechanics with photons
NASA Astrophysics Data System (ADS)
Shadbolt, Peter; Mathews, Jonathan C. F.; Laing, Anthony; O'Brien, Jeremy L.
2014-04-01
Quantum mechanics continues to predict effects at odds with a classical understanding of nature. Experiments with light at the single-photon level have historically been at the forefront of fundamental tests of quantum theory and the current developments in photonic technologies enable the exploration of new directions. Here we review recent photonic experiments to test two important themes in quantum mechanics: wave-particle duality, which is central to complementarity and delayed-choice experiments; and Bell nonlocality, where the latest theoretical and technological advances have allowed all controversial loopholes to be separately addressed in different experiments.
A method of extracting operating parameters of a quantum circuit
NASA Astrophysics Data System (ADS)
Sete, Eyob A.; Block, Maxwell; Scheer, Michael; Zanoci, Cris; Vahidpour, Mehrnoosh; Thompson, Dane; Rigetti, Chad
Rigorous simulation-driven design methods are an essential component of traditional integrated circuit design. We adapt these techniques to the design and development of superconducting quantum integrated circuits by combining classical finite element analysis in the microwave domain with Brune circuit synthesis by Solgun [PhD thesis 2014] and BKD Hamiltonian analysis by Burkard et al. [Phys. Rev. B 69, 064503 (2004)]. Using the Hamiltonian of the quantum circuit, constructed using the synthesized equivalent linear circuit and the nonlinear Josephson junctions' contributions, we extract operating parameters of the quantum circuit such as resonance coupling strength, dispersive shift, qubit anharmonicitiy, and decoherence rates for single-and multi-port quantum circuits. This approach has been experimentally validated and allows the closed-loop iterative simulation-driven development of quantum information processing devices.
NASA Astrophysics Data System (ADS)
Joo, Jaewoo; Ginossar, Eran
2016-06-01
We propose a deterministic scheme for teleporting an unknown qubit state through continuous-variable entangled states in superconducting circuits. The qubit is a superconducting two-level system and the bipartite quantum channel is a microwave photonic entangled coherent state between two cavities. A Bell-type measurement performed on the hybrid state of solid and photonic states transfers a discrete-variable unknown electronic state to a continuous-variable photonic cat state in a cavity mode. In order to facilitate the implementation of such complex protocols we propose a design for reducing the self-Kerr nonlinearity in the cavity. The teleporation scheme enables quantum information processing operations with circuit-QED based on entangled coherent states. These include state verification and single-qubit operations with entangled coherent states. These are shown to be experimentally feasible with the state of the art superconducting circuits.
Joo, Jaewoo; Ginossar, Eran
2016-01-01
We propose a deterministic scheme for teleporting an unknown qubit state through continuous-variable entangled states in superconducting circuits. The qubit is a superconducting two-level system and the bipartite quantum channel is a microwave photonic entangled coherent state between two cavities. A Bell-type measurement performed on the hybrid state of solid and photonic states transfers a discrete-variable unknown electronic state to a continuous-variable photonic cat state in a cavity mode. In order to facilitate the implementation of such complex protocols we propose a design for reducing the self-Kerr nonlinearity in the cavity. The teleporation scheme enables quantum information processing operations with circuit-QED based on entangled coherent states. These include state verification and single-qubit operations with entangled coherent states. These are shown to be experimentally feasible with the state of the art superconducting circuits. PMID:27245775
Joo, Jaewoo; Ginossar, Eran
2016-01-01
We propose a deterministic scheme for teleporting an unknown qubit state through continuous-variable entangled states in superconducting circuits. The qubit is a superconducting two-level system and the bipartite quantum channel is a microwave photonic entangled coherent state between two cavities. A Bell-type measurement performed on the hybrid state of solid and photonic states transfers a discrete-variable unknown electronic state to a continuous-variable photonic cat state in a cavity mode. In order to facilitate the implementation of such complex protocols we propose a design for reducing the self-Kerr nonlinearity in the cavity. The teleporation scheme enables quantum information processing operations with circuit-QED based on entangled coherent states. These include state verification and single-qubit operations with entangled coherent states. These are shown to be experimentally feasible with the state of the art superconducting circuits. PMID:27245775
Hybrid quantum circuit with implanted erbium ions
Probst, S.; Rotzinger, H.; Tkalčec, A.; Kukharchyk, N.; Wieck, A. D.; Wünsch, S.; Siegel, M.; Ustinov, A. V.; Bushev, P. A.
2014-10-20
We report on hybrid circuit quantum electrodynamics experiments with focused ion beam implanted Er{sup 3+} ions in Y{sub 2}SiO{sub 5} coupled to an array of superconducting lumped element microwave resonators. The Y{sub 2}SiO{sub 5} crystal is divided into several areas with distinct erbium doping concentrations, each coupled to a separate resonator. The coupling strength is varied from 5 MHz to 18.7 MHz, while the linewidth ranges between 50 MHz and 130 MHz. We confirm the paramagnetic properties of the implanted spin ensemble by evaluating the temperature dependence of the coupling. The efficiency of the implantation process is analyzed and the results are compared to a bulk doped Er:Y{sub 2}SiO{sub 5} sample. We demonstrate the integration of these engineered erbium spin ensembles with superconducting circuits.
Superconducting circuits for quantum information: an outlook.
Devoret, M H; Schoelkopf, R J
2013-03-01
The performance of superconducting qubits has improved by several orders of magnitude in the past decade. These circuits benefit from the robustness of superconductivity and the Josephson effect, and at present they have not encountered any hard physical limits. However, building an error-corrected information processor with many such qubits will require solving specific architecture problems that constitute a new field of research. For the first time, physicists will have to master quantum error correction to design and operate complex active systems that are dissipative in nature, yet remain coherent indefinitely. We offer a view on some directions for the field and speculate on its future. PMID:23471399
Decoherence-free manipulation of photonic memories for quantum computation
Sangouard, N.
2006-02-15
We present a protocol to construct an arbitrary quantum circuit. The quantum bits (qubits) are encoded in polarization states of single photons. They are stored in spatially separated dense media deposed in an optical cavity. Specific sequences of pulses address individually the storage media to encode the qubits and to implement a universal set of gates. The proposed protocol is decoherence-free in the sense that spontaneous emission and cavity damping are avoided. We discuss a coupling scheme for experimental implementation in neon atoms.
Quantum Mesoscopic Physics of Electrons and Photons
NASA Astrophysics Data System (ADS)
Akkermans, Eric
2013-03-01
We first review basic notions of coherent quantum transport at the mesoscopic scale for both electronic and photonic systems. We then show that successful descriptions developed for coherent electronic transport (e.g. weak localization and UCF) and thermodynamics (persistent currents), noise and full counting statistics can be extended and applied to the study of Quantum Electrodynamics of quantum conductors and of quantum optics based on photons emitted by such conductors. In this context, we discuss the two following specific problems : (1) Ramsey fringes and time domain interference for particle creation form a quantum vacuum with a specific application to dynamical Coulomb blockade. In that setup, the current noise of a coherent conductor is biased by two successive voltage pulses. An interference pattern between photon assisted processes is observed which is explained by the contribution of several processes to the probability to emit photons after each pulse. Recent experiments in this context will be discussed. (2) Quantum emitter coupled to a fractal environment. A new and unexpected type of oscillatory structures for the probability of spontaneous emission has been obtained which results from the fractal nature of the quantum vacuum. When applied to the case of a tunnel junction as a quantum emitter of photons, the same oscillatory structure arises for the conductance of the tunnel junction. This work was supported by the Israel Science Foundation Grant No.924/09
Robust bidirectional links for photonic quantum networks
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
Robust bidirectional links for photonic quantum networks.
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
Generalized quantum interference of correlated photon pairs
Kim, Heonoh; Lee, Sang Min; Moon, Han Seb
2015-01-01
Superposition and indistinguishablility between probability amplitudes have played an essential role in observing quantum interference effects of correlated photons. The Hong-Ou-Mandel interference and interferences of the path-entangled photon number state are of special interest in the field of quantum information technologies. However, a fully generalized two-photon quantum interferometric scheme accounting for the Hong-Ou-Mandel scheme and path-entangled photon number states has not yet been proposed. Here we report the experimental demonstrations of the generalized two-photon interferometry with both the interferometric properties of the Hong-Ou-Mandel effect and the fully unfolded version of the path-entangled photon number state using photon-pair sources, which are independently generated by spontaneous parametric down-conversion. Our experimental scheme explains two-photon interference fringes revealing single- and two-photon coherence properties in a single interferometer setup. Using the proposed interferometric measurement, it is possible to directly estimate the joint spectral intensity of a photon pair source. PMID:25951143
Quantum memristor in a superconducting circuit
NASA Astrophysics Data System (ADS)
Salmilehto, Juha; Sanz, Mikel; di Ventra, Massimiliano; Solano, Enrique
Memristors, resistive elements that retain information of their past, have garnered interest due to their paradigm-changing potential in information processing and electronics. The emergent hysteretic behaviour allows for novel architectural applications and has recently been classically demonstrated in a simplified superconducting setup using the phase-dependent conductance in the tunnel-junction-microscopic model. In this contribution, we present a truly quantum model for a memristor constructed using established elements and techniques in superconducting nanoelectronics, and explore the parameters for feasible operation as well as refine the methods for quantifying the memory retention. In particular, the memristive behaviour is shown to arise from quasiparticle-induced tunneling in the full dissipative model and can be observed in the phase-driven tunneling current. The relevant hysteretic behaviour should be observable using current state-of-the-art measurements for detecting quasiparticle excitations. Our theoretical findings constitute the first quantum memristor in a superconducting circuit and act as the starting point for designing further circuit elements that have non-Markovian characteristics The authors acknowledge support from the CCQED EU project and the Finnish Cultural Foundation.
Deterministic amplification of Schrödinger cat states in circuit quantum electrodynamics
NASA Astrophysics Data System (ADS)
Joo, Jaewoo; Elliott, Matthew; Oi, Daniel K. L.; Ginossar, Eran; Spiller, Timothy P.
2016-02-01
Perfect deterministic amplification of arbitrary quantum states is prohibited by quantum mechanics, but determinism can be achieved by compromising between fidelity and amplification power. We propose a dynamical scheme for deterministically amplifying photonic Schrödinger cat states, which show great promise as a tool for quantum information processing. Our protocol is designed for strongly coupled circuit quantum electrodynamics and utilizes artificial atomic states and external microwave controls to engineer a set of optimal state transfers and achieve high fidelity amplification. We compare analytical results with full simulations of the open, driven Jaynes-Cummings model, using realistic device parameters for state of the art superconducting circuits. Amplification with a fidelity of 0.9 can be achieved for sizable cat states in the presence of cavity and atomic-level decoherence. This tool could be applied to practical continuous-variable information processing for the purification and stabilization of cat states in the presence of photon losses.
Digital Quantum Rabi and Dicke Models in Superconducting Circuits
NASA Astrophysics Data System (ADS)
Mezzacapo, A.; Las Heras, U.; Pedernales, J. S.; Dicarlo, L.; Solano, E.; Lamata, L.
2014-12-01
We propose the analog-digital quantum simulation of the quantum Rabi and Dicke models using circuit quantum electrodynamics (QED). We find that all physical regimes, in particular those which are impossible to realize in typical cavity QED setups, can be simulated via unitary decomposition into digital steps. Furthermore, we show the emergence of the Dirac equation dynamics from the quantum Rabi model when the mode frequency vanishes. Finally, we analyze the feasibility of this proposal under realistic superconducting circuit scenarios.
Lithography system using quantum entangled photons
NASA Technical Reports Server (NTRS)
Williams, Colin (Inventor); Dowling, Jonathan (Inventor); della Rossa, Giovanni (Inventor)
2002-01-01
A system of etching using quantum entangled particles to get shorter interference fringes. An interferometer is used to obtain an interference fringe. N entangled photons are input to the interferometer. This reduces the distance between interference fringes by n, where again n is the number of entangled photons.
Calkins, Brice; Mennea, Paolo L; Lita, Adriana E; Metcalf, Benjamin J; Kolthammer, W Steven; Lamas-Linares, Antia; Spring, Justin B; Humphreys, Peter C; Mirin, Richard P; Gates, James C; Smith, Peter G R; Walmsley, Ian A; Gerrits, Thomas; Nam, Sae Woo
2013-09-23
The integrated optical circuit is a promising architecture for the realization of complex quantum optical states and information networks. One element that is required for many of these applications is a high-efficiency photon detector capable of photon-number discrimination. We present an integrated photonic system in the telecom band at 1550 nm based on UV-written silica-on-silicon waveguides and modified transition-edge sensors capable of number resolution and over 40 % efficiency. Exploiting the mode transmission failure of these devices, we multiplex three detectors in series to demonstrate a combined 79 % ± 2 % detection efficiency with a single pass, and 88 % ± 3 % at the operating wavelength of an on-chip terminal reflection grating. Furthermore, our optical measurements clearly demonstrate no significant unexplained loss in this system due to scattering or reflections. This waveguide and detector design therefore allows the placement of number-resolving single-photon detectors of predictable efficiency at arbitrary locations within a photonic circuit - a capability that offers great potential for many quantum optical applications. PMID:24104153
An XQDD-Based Verification Method for Quantum Circuits
NASA Astrophysics Data System (ADS)
Wang, Shiou-An; Lu, Chin-Yung; Tsai, I.-Ming; Kuo, Sy-Yen
Synthesis of quantum circuits is essential for building quantum computers. It is important to verify that the circuits designed perform the correct functions. In this paper, we propose an algorithm which can be used to verify the quantum circuits synthesized by any method. The proposed algorithm is based on BDD (Binary Decision Diagram) and is called X-decomposition Quantum Decision Diagram (XQDD). In this method, quantum operations are modeled using a graphic method and the verification process is based on comparing these graphic diagrams. We also develop an algorithm to verify reversible circuits even if they have a different number of garbage qubits. In most cases, the number of nodes used in XQDD is less than that in other representations. In general, the proposed method is more efficient in terms of space and time and can be used to verify many quantum circuits in polynomial time.
Cavity State Reservoir Engineering in Circuit Quantum Electrodynamics
NASA Astrophysics Data System (ADS)
Holland, Eric T.
Engineered quantum systems are poised to revolutionize information science in the near future. A persistent challenge in applied quantum technology is creating controllable, quantum interactions while preventing information loss to the environment, decoherence. In this thesis, we realize mesoscopic superconducting circuits whose macroscopic collective degrees of freedom, such as voltages and currents, behave quantum mechanically. We couple these mesoscopic devices to microwave cavities forming a cavity quantum electrodynamics (QED) architecture comprised entirely of circuit elements. This application of cavity QED is dubbed Circuit QED and is an interdisciplinary field seated at the intersection of electrical engineering, superconductivity, quantum optics, and quantum information science. Two popular methods for taming active quantum systems in the presence of decoherence are discrete feedback conditioned on an ancillary system or quantum reservoir engineering. Quantum reservoir engineering maintains a desired subset of a Hilbert space through a combination of drives and designed entropy evacuation. Circuit QED provides a favorable platform for investigating quantum reservoir engineering proposals. A major advancement of this thesis is the development of a quantum reservoir engineering protocol which maintains the quantum state of a microwave cavity in the presence of decoherence. This thesis synthesizes strongly coupled, coherent devices whose solutions to its driven, dissipative Hamiltonian are predicted a priori. This work lays the foundation for future advancements in cavity centered quantum reservoir engineering protocols realizing hardware efficient circuit QED designs.
Flexible and tunable silicon photonic circuits on plastic substrates
Chen, Yu; Li, Huan; Li, Mo
2012-01-01
Flexible microelectronics has shown tremendous promise in a broad spectrum of applications, especially those that cannot be addressed by conventional microelectronics in rigid materials and constructions. These unconventional yet important applications range from flexible consumer electronics to conformal sensor arrays and biomedical devices. A recent paradigm shift in implementing flexible electronics is to physically transfer highly integrated devices made in high-quality, crystalline semiconductors on to plastic substrates. Here we demonstrate a flexible form of silicon photonics using the transfer-and-bond fabrication method. Photonic circuits including interferometers and resonators have been transferred onto flexible plastic substrates with preserved functionalities and performance. By mechanically deforming, the optical characteristics of the devices can be tuned reversibly over a remarkably large range. The demonstration of the new flexible photonic systems based on the silicon-on-plastic (SOP) platform could open the door to many future applications, including tunable photonics, optomechanical sensors and biomechanical and bio-photonic probes. PMID:22953043
SIMPEL: circuit model for photonic spike processing laser neurons.
Shastri, Bhavin J; Nahmias, Mitchell A; Tait, Alexander N; Wu, Ben; Prucnal, Paul R
2015-03-23
We propose an equivalent circuit model for photonic spike processing laser neurons with an embedded saturable absorber—a simulation model for photonic excitable lasers (SIMPEL). We show that by mapping the laser neuron rate equations into a circuit model, SPICE analysis can be used as an efficient and accurate engine for numerical calculations, capable of generalization to a variety of different types of laser neurons with saturable absorber found in literature. The development of this model parallels the Hodgkin-Huxley model of neuron biophysics, a circuit framework which brought efficiency, modularity, and generalizability to the study of neural dynamics. We employ the model to study various signal-processing effects such as excitability with excitatory and inhibitory pulses, binary all-or-nothing response, and bistable dynamics. PMID:25837141
Realization of Simple Quantum Algorithms with Circuit Quantum Electrodynamics
NASA Astrophysics Data System (ADS)
Dicarlo, Leonardo
2010-03-01
Superconducting circuits have made considerable progress in the requirements of quantum coherence, universal gate operations and qubit readout necessary to realize a quantum computer. However, simultaneously meeting these requirements makes the solid-state realization of few-qubit processors, as previously implemented in nuclear magnetic resonance, ion-trap and optical systems, an exciting challenge. We present the realization of a two-qubit superconducting processor based on circuit quantum electrodynamics (cQED), and report progress by the Yale cQED team towards a four-qubit upgrade. The architecture employs a microwave transmission-line cavity as a quantum bus coupling multiple transmon qubits. Unitary control is achieved by concatenation of high-fidelity single-qubit rotations induced via resonant microwave tones, and multi-qubit adiabatic phase gates realized by local flux control of qubit frequencies. Qubit readout uses the cavity as a quadratic detector, such that a single, calibrated measurement channel gives direct access to multi-qubit correlations. We present generation of Bell states; entanglement quantification by strong violation of Clauser-Horne-Shimony-Holt inequalities; and implementations of the Grover search and Deutsch-Jozsa algorithms. We report experimental progress in extending adiabatic phase gates and joint readout to four qubits, and improving qubit coherence on the road to realizing more complex quantum algorithms. Research done in collaboration with J. M. Chow, J. M. Gambetta, Lev S. Bishop, B. R. Johnson, D. I. Schuster, A. Nunnenkamp, J. Majer, A. Blais, L. Frunzio, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf.
Hybrid Circuit QED with Double Quantum Dots
NASA Astrophysics Data System (ADS)
Petta, Jason
2014-03-01
Cavity quantum electrodynamics explores quantum optics at the most basic level of a single photon interacting with a single atom. We have been able to explore cavity QED in a condensed matter system by placing a double quantum dot (DQD) inside of a high quality factor microwave cavity. Our results show that measurements of the cavity field are sensitive to charge and spin dynamics in the DQD.[2,3] We can explore non-equilibrium physics by applying a finite source-drain bias across the DQD, which results in sequential tunneling. Remarkably, we observe a gain as large as 15 in the cavity transmission when the DQD energy level detuning is matched to the cavity frequency. These results will be discussed in the context of single atom lasing.[4] I will also describe recent progress towards reaching the strong-coupling limit in cavity-coupled Si DQDs. In collaboration with Manas Kulkarni, Yinyu Liu, Karl Petersson, George Stehlik, Jacob Taylor, and Hakan Tureci. We acknowledge support from the Sloan and Packard Foundations, ARO, DARPA, and NSF.
Interacting Photons in Waveguide-QED and Applications in Quantum Information Processing
NASA Astrophysics Data System (ADS)
Zheng, Huaixiu
Strong coupling between light and matter has been demonstrated both in classical cavity quantum electrodynamics (QED) systems and in more recent circuit-QED experiments. This enables the generation of strong nonlinear photon-photon interactions at the single-photon level, which is of great interest for the observation of quantum nonlinear optical phenomena, the control of light quanta in quantum information protocols such as quantum networking, as well as the study of strongly correlated quantum many-body systems using light. Recently, strong coupling has also been realized in a variety of one-dimensional (1D) waveguide- QED experimental systems, which in turn makes them promising candidates for quantum information processing. Compared to cavity-QED systems, there are two new features in waveguide-QED: the existence of a continuum of states and the restricted 1D phase space, which together bring in new physical effects, such as the bound-state effects. This thesis consists of two parts: 1) understanding the fundamental interaction between local quantum objects, such as two-level systems and four-level systems, and photons confined in the waveguide; 2) exploring its implications in quantum information processing, in particular photonic quantum computation and quantum key distribution. First, we demonstrate that by coupling a two-level system (TLS) or three/four-level system to a 1D continuum, strongly-correlated photons can be generated inside the waveguide. Photon-photon bound states, which decay exponentially as a function of the relative coordinates of photons, appear in multiphoton scattering processes. As a result, photon bunching and antibunching can be observed in the photon-photon correlation function, and nonclassical light source can be generated on demand. In the case of an N-type four-level system, we show that the effective photon-photon interaction mediated by the four-level system, gives rise to a variety of nonlinear optical phenomena, including
Aharonov-Bohm phases in a quantum LC circuit
NASA Astrophysics Data System (ADS)
Cao, ChunJun; Yao, Yuan; Zhitnitsky, Ariel R.
2016-03-01
We study novel types of contributions to the partition function of the Maxwell system defined on a small compact manifold. These contributions, often not addressed in the perturbative treatment with physical photons, emerge as a result of tunneling transitions between topologically distinct but physically identical vacuum winding states. These new terms give an extra contribution to the Casimir pressure, yet to be measured. We argue that this effect is highly sensitive to a small external electric field, which should be contrasted with the conventional Casimir effect, where the vacuum photons are essentially unaffected by any external field. Furthermore, photons will be emitted from the vacuum in response to a time-dependent electric field, similar to the dynamical Casimir effect in which real particles are radiated from the vacuum due to the time-dependent boundary conditions. We also propose an experimental setup using a quantum LC circuit to detect this novel effect. We expect physical electric charges to appear on the capacitor plates when the system dimension is such that coherent Aharonov-Bohm phases can be maintained over macroscopically large distances.
Quantum description of a time-dependent mesoscopic RLC circuit
NASA Astrophysics Data System (ADS)
Pedrosa, I. A.
2012-11-01
In this paper, we present a comprehensive quantum description of a mesoscopic RLC circuit with time-dependent resistance, inductance and capacitance. Based on the dynamical invariant method and using quadratic invariants, we derive exact nonstationary quantum states for this circuit and write them in terms of solutions of the Milne-Pinney equation. Afterwards, we use quadratic invariants to construct coherent states for this quantized system and employ them to investigate quantum properties of the RLC circuit. In particular, we show that the product of the quantum fluctuations of the charge and the magnetic flux does not satisfy the minimum uncertainty relation.
Hyper-parallel photonic quantum computation with coupled quantum dots
NASA Astrophysics Data System (ADS)
Ren, Bao-Cang; Deng, Fu-Guo
2014-04-01
It is well known that a parallel quantum computer is more powerful than a classical one. So far, there are some important works about the construction of universal quantum logic gates, the key elements in quantum computation. However, they are focused on operating on one degree of freedom (DOF) of quantum systems. Here, we investigate the possibility of achieving scalable hyper-parallel quantum computation based on two DOFs of photon systems. We construct a deterministic hyper-controlled-not (hyper-CNOT) gate operating on both the spatial-mode and the polarization DOFs of a two-photon system simultaneously, by exploiting the giant optical circular birefringence induced by quantum-dot spins in double-sided optical microcavities as a result of cavity quantum electrodynamics (QED). This hyper-CNOT gate is implemented by manipulating the four qubits in the two DOFs of a two-photon system without auxiliary spatial modes or polarization modes. It reduces the operation time and the resources consumed in quantum information processing, and it is more robust against the photonic dissipation noise, compared with the integration of several cascaded CNOT gates in one DOF.
Quantum game simulator, using the circuit model of quantum computation
NASA Astrophysics Data System (ADS)
Vlachos, Panagiotis; Karafyllidis, Ioannis G.
2009-10-01
We present a general two-player quantum game simulator that can simulate any two-player quantum game described by a 2×2 payoff matrix (two strategy games).The user can determine the payoff matrices for both players, their strategies and the amount of entanglement between their initial strategies. The outputs of the simulator are the expected payoffs of each player as a function of the other player's strategy parameters and the amount of entanglement. The simulator also produces contour plots that divide the strategy spaces of the game in regions in which players can get larger payoffs if they choose to use a quantum strategy against any classical one. We also apply the simulator to two well-known quantum games, the Battle of Sexes and the Chicken game. Program summaryProgram title: Quantum Game Simulator (QGS) Catalogue identifier: AEED_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEED_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 3416 No. of bytes in distributed program, including test data, etc.: 583 553 Distribution format: tar.gz Programming language: Matlab R2008a (C) Computer: Any computer that can sufficiently run Matlab R2008a Operating system: Any system that can sufficiently run Matlab R2008a Classification: 4.15 Nature of problem: Simulation of two player quantum games described by a payoff matrix. Solution method: The program calculates the matrices that comprise the Eisert setup for quantum games based on the quantum circuit model. There are 5 parameters that can be altered. We define 3 of them as constant. We play the quantum game for all possible values for the other 2 parameters and store the results in a matrix. Unusual features: The software provides an easy way of simulating any two-player quantum games. Running time: Approximately
Theoretical design of photonic crystal devices for integrated optical circuits
NASA Astrophysics Data System (ADS)
Mekis, Attila
2000-12-01
In this thesis we investigate novel photonic crystal devices that can be used as building blocks of all- optical circuits. We contrast the behavior of light in photonic crystal systems and in their traditional counterparts. We exhibit that bends in photonic crystals are able to transmit light with over 90% efficiency for large bandwidths and with 100% efficiency for specific frequencies. In contrast to traditional waveguides, bound states in photonic crystal waveguides can also exist in constrictions and above the cutoff frequency. We discuss how to lower reflections encountered when photonic crystal waveguides are terminated, both in an experimental setup as well as in numerical simulations. We show that light can be very efficiently coupled into and out of photonic crystal waveguides using tapered dielectric waveguides. In time-domain simulations of photonic crystal waveguides, spurious reflections from cell edges can be eliminated by terminating the waveguide with a Bragg reflector waveguide. We demonstrate novel lasing action in two-dimensional photonic crystal slabs with gain media, where lasing occurs at saddle points in the band structure, in contrast to one-dimensional photonic crystals. We also design a photonic crystal slab with organic gain media that has a TE-like pseudogap. We demonstrate that such a slab can support a high- Q defect mode, enabling low threshold lasing, and we discuss how the quality factor depends on the design parameters. We also propose to use two- dimensional photonic crystal slabs as directionally efficient free-space couplers. We draft methods to calculate the coupling constant both numerically and analytically, using a finite-difference time-domain method and the volume current method with a Green's function approach, respectively. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)
Effect of Multiphoton Processes on Geometric Quantum Computation in Superconducting Circuit QED
NASA Astrophysics Data System (ADS)
Chen, Chang-Yong
2012-11-01
We study the influence of multi-photon processes on the geometric quantum computation in the systems of superconducting qubits based on the displacement-like and the general squeezed operator methods. As an example, we focus on the question about how to implement a two-qubit geometric phase gate using superconducting circuit quantum electrodynamics with both single- and two-photon interaction between the qubits and the cavity modes. We find that the multiphoton processes are not only controllable but also improve the gating speed. The comparison with other physical systems and experimental feasibility are discussed in detail.
GaN directional couplers for integrated quantum photonics
Zhang Yanfeng; McKnight, Loyd; Watson, Ian M.; Gu, Erdan; Calvez, Stephane; Dawson, Martin D.; Engin, Erman; Cryan, Martin J.; Thompson, Mark G.; O'Brien, Jeremy L.
2011-10-17
Large cross-section GaN waveguides are proposed as a suitable architecture to achieve integrated quantum photonic circuits. Directional couplers with this geometry have been designed with aid of the beam propagation method and fabricated using inductively coupled plasma etching. Scanning electron microscopy inspection shows high quality facets for end coupling and a well defined gap between rib pairs in the coupling region. Optical characterization at 800 nm shows single-mode operation and coupling-length-dependent splitting ratios. Two photon interference of degenerate photon pairs has been observed in the directional coupler by measurement of the Hong-Ou-Mandel dip [C. K. Hong, et al., Phys. Rev. Lett. 59, 2044 (1987)] with 96% visibility.
All-photonic intercity quantum key distribution
NASA Astrophysics Data System (ADS)
Azuma, Koji; Tamaki, Kiyoshi; Munro, William J.
2015-12-01
Recent field demonstrations of quantum key distribution (QKD) networks hold promise for unconditionally secure communication. However, owing to loss in optical fibres, the length of point-to-point links is limited to a hundred kilometers, restricting the QKD networks to intracity. A natural way to expand the QKD network in a secure manner is to connect it to another one in a different city with quantum repeaters. But, this solution is overengineered unless such a backbone connection is intercontinental. Here we present a QKD protocol that could supersede even quantum repeaters for connecting QKD networks in different cities below 800 km distant. Nonetheless, in contrast to quantum repeaters, this protocol uses only a single intermediate node with optical devices, requiring neither quantum memories nor quantum error correction. Our all-photonic `intercity' QKD protocol bridges large gaps between the conventional intracity QKD networks and the future intercontinental quantum repeaters, conceptually and technologically.
All-photonic intercity quantum key distribution
Azuma, Koji; Tamaki, Kiyoshi; Munro, William J.
2015-01-01
Recent field demonstrations of quantum key distribution (QKD) networks hold promise for unconditionally secure communication. However, owing to loss in optical fibres, the length of point-to-point links is limited to a hundred kilometers, restricting the QKD networks to intracity. A natural way to expand the QKD network in a secure manner is to connect it to another one in a different city with quantum repeaters. But, this solution is overengineered unless such a backbone connection is intercontinental. Here we present a QKD protocol that could supersede even quantum repeaters for connecting QKD networks in different cities below 800 km distant. Nonetheless, in contrast to quantum repeaters, this protocol uses only a single intermediate node with optical devices, requiring neither quantum memories nor quantum error correction. Our all-photonic ‘intercity' QKD protocol bridges large gaps between the conventional intracity QKD networks and the future intercontinental quantum repeaters, conceptually and technologically. PMID:26671044
Wei, Hai-Rui; Lu Long, Gui
2015-01-01
Hybrid quantum gates hold great promise for quantum information processing since they preserve the advantages of different quantum systems. Here we present compact quantum circuits to deterministically implement controlled-NOT, Toffoli, and Fredkin gates between a flying photon qubit and diamond nitrogen-vacancy (NV) centers assisted by microcavities. The target qubits of these universal quantum gates are encoded on the spins of the electrons associated with the diamond NV centers and they have long coherence time for storing information, and the control qubit is encoded on the polarizations of the flying photon and can be easily manipulated. Our quantum circuits are compact, economic, and simple. Moreover, they do not require additional qubits. The complexity of our schemes for universal three-qubit gates is much reduced, compared to the synthesis with two-qubit entangling gates. These schemes have high fidelities and efficiencies, and they are feasible in experiment. PMID:26271899
Controlled Photon Switch Assisted by Coupled Quantum Dots
Luo, Ming-Xing; Ma, Song-Ya; Chen, Xiu-Bo; Wang, Xiaojun
2015-01-01
Quantum switch is a primitive element in quantum network communication. In contrast to previous switch schemes on one degree of freedom (DOF) of quantum systems, we consider controlled switches of photon system with two DOFs. These controlled photon switches are constructed by exploring the optical selection rules derived from the quantum-dot spins in one-sided optical microcavities. Several double controlled-NOT gate on different joint systems are greatly simplified with an auxiliary DOF of the controlling photon. The photon switches show that two DOFs of photons can be independently transmitted in quantum networks. This result reduces the quantum resources for quantum network communication. PMID:26095049
Spying on photons with photons: quantum interference and information
NASA Astrophysics Data System (ADS)
Ataman, Stefan
2016-07-01
The quest to have both which-path knowledge and interference fringes in a double-slit experiment dates back to the inception of quantum mechanics (QM) and to the famous Einstein-Bohr debates. In this paper we propose and discuss an experiment able to spy on one photon's path with another photon. We modify the quantum state inside the interferometer as opposed to the traditional physical modification of the "wave-like" or "particle-like" experimental setup. We are able to show that it is the ability to harvest or not which-path information that finally limits the visibility of the interference pattern and not the "wave-like" or "particle-like" experimental setups. Remarkably, a full "particle-like" experimental setup is able to show interference fringes with 100% visibility if the quantum state is carefully engineered.
Non-unitary probabilistic quantum computing circuit and method
NASA Technical Reports Server (NTRS)
Williams, Colin P. (Inventor); Gingrich, Robert M. (Inventor)
2009-01-01
A quantum circuit performing quantum computation in a quantum computer. A chosen transformation of an initial n-qubit state is probabilistically obtained. The circuit comprises a unitary quantum operator obtained from a non-unitary quantum operator, operating on an n-qubit state and an ancilla state. When operation on the ancilla state provides a success condition, computation is stopped. When operation on the ancilla state provides a failure condition, computation is performed again on the ancilla state and the n-qubit state obtained in the previous computation, until a success condition is obtained.
Suppression law of quantum states in a 3D photonic fast Fourier transform chip.
Crespi, Andrea; Osellame, Roberto; Ramponi, Roberta; Bentivegna, Marco; Flamini, Fulvio; Spagnolo, Nicolò; Viggianiello, Niko; Innocenti, Luca; Mataloni, Paolo; Sciarrino, Fabio
2016-01-01
The identification of phenomena able to pinpoint quantum interference is attracting large interest. Indeed, a generalization of the Hong-Ou-Mandel effect valid for any number of photons and optical modes would represent an important leap ahead both from a fundamental perspective and for practical applications, such as certification of photonic quantum devices, whose computational speedup is expected to depend critically on multi-particle interference. Quantum distinctive features have been predicted for many particles injected into multimode interferometers implementing the Fourier transform over the optical modes. Here we develop a scalable approach for the implementation of the fast Fourier transform algorithm using three-dimensional photonic integrated interferometers, fabricated via femtosecond laser writing technique. We observe the suppression law for a large number of output states with four- and eight-mode optical circuits: the experimental results demonstrate genuine quantum interference between the injected photons, thus offering a powerful tool for diagnostic of photonic platforms. PMID:26843135
Suppression law of quantum states in a 3D photonic fast Fourier transform chip
Crespi, Andrea; Osellame, Roberto; Ramponi, Roberta; Bentivegna, Marco; Flamini, Fulvio; Spagnolo, Nicolò; Viggianiello, Niko; Innocenti, Luca; Mataloni, Paolo; Sciarrino, Fabio
2016-01-01
The identification of phenomena able to pinpoint quantum interference is attracting large interest. Indeed, a generalization of the Hong–Ou–Mandel effect valid for any number of photons and optical modes would represent an important leap ahead both from a fundamental perspective and for practical applications, such as certification of photonic quantum devices, whose computational speedup is expected to depend critically on multi-particle interference. Quantum distinctive features have been predicted for many particles injected into multimode interferometers implementing the Fourier transform over the optical modes. Here we develop a scalable approach for the implementation of the fast Fourier transform algorithm using three-dimensional photonic integrated interferometers, fabricated via femtosecond laser writing technique. We observe the suppression law for a large number of output states with four- and eight-mode optical circuits: the experimental results demonstrate genuine quantum interference between the injected photons, thus offering a powerful tool for diagnostic of photonic platforms. PMID:26843135
Circuit quantum electrodynamics simulator of flat band physics in a Lieb lattice
NASA Astrophysics Data System (ADS)
Yang, Zi-He; Wang, Yan-Pu; Xue, Zheng-Yuan; Yang, Wan-Li; Hu, Yong; Gao, Jin-Hua; Wu, Ying
2016-06-01
The concept of flat band plays an important role in strongly correlated many-body physics. However, the demonstration of the flat band physics is highly nontrivial due to intrinsic limitations in conventional condensed-matter materials. Here we propose a circuit quantum electrodynamics simulator of the two-dimensional (2D) Lieb lattice exhibiting a flat middle band. By exploiting the parametric conversion method, we design a photonic Lieb lattice with in situ tunable hopping strengths in a 2D array of coupled superconducting transmissionline resonators. Moreover, the flexibility of our proposal enables the incorporation of both the artificial gauge field and the strong photon-photon interaction in a time- and site-resolved manner. To unambiguously demonstrate the synthesized flat band, we further investigate the observation of the flat band localization of microwave photons through the pumping and the steady-state measurements of only a few sites on the lattice. Requiring only current level of technique and being robust against imperfections in realistic circuits, our scheme can be readily tested in experiment and may pave a new way towards the realization of exotic photonic quantum Hall fluids including anomalous quantum Hall effect and bosonic fractional quantum Hall effect without magnetic field.
Mapping of topological quantum circuits to physical hardware.
Paler, Alexandru; Devitt, Simon J; Nemoto, Kae; Polian, Ilia
2014-01-01
Topological quantum computation is a promising technique to achieve large-scale, error-corrected computation. Quantum hardware is used to create a large, 3-dimensional lattice of entangled qubits while performing computation requires strategic measurement in accordance with a topological circuit specification. The specification is a geometric structure that defines encoded information and fault-tolerant operations. The compilation of a topological circuit is one important aspect of programming a quantum computer, another is the mapping of the topological circuit into the operations performed by the hardware. Each qubit has to be controlled, and measurement results are needed to propagate encoded quantum information from input to output. In this work, we introduce an algorithm for mapping an topological circuit to the operations needed by the physical hardware. We determine the control commands for each qubit in the computer and the relevant measurements that are needed to track information as it moves through the circuit. PMID:24722360
Mapping of Topological Quantum Circuits to Physical Hardware
NASA Astrophysics Data System (ADS)
Paler, Alexandru; Devitt, Simon J.; Nemoto, Kae; Polian, Ilia
2014-04-01
Topological quantum computation is a promising technique to achieve large-scale, error-corrected computation. Quantum hardware is used to create a large, 3-dimensional lattice of entangled qubits while performing computation requires strategic measurement in accordance with a topological circuit specification. The specification is a geometric structure that defines encoded information and fault-tolerant operations. The compilation of a topological circuit is one important aspect of programming a quantum computer, another is the mapping of the topological circuit into the operations performed by the hardware. Each qubit has to be controlled, and measurement results are needed to propagate encoded quantum information from input to output. In this work, we introduce an algorithm for mapping an topological circuit to the operations needed by the physical hardware. We determine the control commands for each qubit in the computer and the relevant measurements that are needed to track information as it moves through the circuit.
Improved Classical Simulation of Quantum Circuits Dominated by Clifford Gates
NASA Astrophysics Data System (ADS)
Bravyi, Sergey; Gosset, David
2016-06-01
We present a new algorithm for classical simulation of quantum circuits over the Clifford+T gate set. The runtime of the algorithm is polynomial in the number of qubits and the number of Clifford gates in the circuit but exponential in the number of T gates. The exponential scaling is sufficiently mild that the algorithm can be used in practice to simulate medium-sized quantum circuits dominated by Clifford gates. The first demonstrations of fault-tolerant quantum circuits based on 2D topological codes are likely to be dominated by Clifford gates due to a high implementation cost associated with logical T gates. Thus our algorithm may serve as a verification tool for near-term quantum computers which cannot in practice be simulated by other means. To demonstrate the power of the new method, we performed a classical simulation of a hidden shift quantum algorithm with 40 qubits, a few hundred Clifford gates, and nearly 50 T gates.
Towards scalable photonics via quantum storage
NASA Astrophysics Data System (ADS)
Nunn, J.; Langford, N. K.; Kolthammer, W. S.; Champion, T. F. M.; Sprague, M. R.; Michelberger, P. S.; Jin, X.-M.; England, D. G.; Walmsley, I. A.
2013-03-01
Single photons are a vital resource for optical quantum information processing. Efficient and deterministic single photon sources do not yet exist, however. To date, experimental demonstrations of quantum processing primitives have been implemented using non-deterministic sources combined with heralding and/or postselection. Unfortunately, even for eight photons, the data rates are already so low as to make most experiments impracticable. It is well known that quantum memories, capable of storing photons until they are needed, are a potential solution to this `scaling catastrophe'. Here, we analyze in detail the benefits of quantum memories for producing multiphoton states, showing how the production rates can be enhanced by many orders of magnitude. We identify the quantity eta B as the most important figure of merit in this connection, where eta and B are the efficiency and time-bandwidth product of the memories, respectively. We go on to review our progress in implementing the most broadband memory to date, with B<1000, in room-temperature cesium vapour. We consider the noise properties for single photon storage and the integration of the memory using waveguides.
Photonic crystal slab quantum cascade detector
Reininger, Peter Schwarz, Benedikt; Harrer, Andreas; Zederbauer, Tobias; Detz, Hermann; Maxwell Andrews, Aaron; Gansch, Roman; Schrenk, Werner; Strasser, Gottfried
2013-12-09
In this Letter, we demonstrate the design, fabrication, and characterization of a photonic crystal slab quantum cascade detector (PCS-QCD). By employing a specifically designed resonant cavity, the performance of the photodetector is improved in three distinct ways. The PCS makes the QCD sensitive to surface normal incident light. It resonantly enhances the photon lifetime inside the active zone, thus increasing the photocurrent significantly. And, the construction form of the device inherently decreases the noise. Finally, we compare the characteristics of the PCS-QCD to a PCS - quantum well infrared photodetector and outline the advantages for certain fields of applications.
Photonic Nonlinearities via Quantum Zeno Blockade
NASA Astrophysics Data System (ADS)
Sun, Yu-Zhu; Huang, Yu-Ping; Kumar, Prem
2013-05-01
Realizing optical-nonlinear effects at a single-photon level is a highly desirable but also extremely challenging task, because of both fundamental and practical difficulties. We present an avenue to surmounting these difficulties by exploiting quantum Zeno blockade in nonlinear optical systems. Considering specifically a lithium-niobate microresonator, we find that a deterministic phase gate can be realized between single photons with near-unity fidelity. Supported by established techniques for fabricating and operating such devices, our approach can provide an enabling tool for all-optical applications in both classical and quantum domains.
Universal discrete Fourier optics RF photonic integrated circuit architecture.
Hall, Trevor J; Hasan, Mehedi
2016-04-01
This paper describes a coherent electro-optic circuit architecture that generates a frequency comb consisting of N spatially separated orders using a generalised Mach-Zenhder interferometer (MZI) with its N × 1 combiner replaced by an optical N × N Discrete Fourier Transform (DFT). Advantage may be taken of the tight optical path-length control, component and circuit symmetries and emerging trimming algorithms offered by photonic integration in any platform that offers linear electro-optic phase modulation such as LiNbO_{3,} silicon, III-V or hybrid technology. The circuit architecture subsumes all MZI-based RF photonic circuit architectures in the prior art given an appropriate choice of output port(s) and dimension N although the principal application envisaged is phase correlated subcarrier generation for all optical orthogonal frequency division multiplexing. A transfer matrix approach is used to model the operation of the architecture. The predictions of the model are validated by simulations performed using an industry standard software tool. Implementation is found to be practical. PMID:27137048
Moiseev, S. A.; Tittel, W.
2010-07-15
We study quantum compression and decompression of light pulses that carry quantum information using a photon-echo quantum memory technique with controllable inhomogeneous broadening of an isolated atomic absorption line. We investigate media with differently broadened absorption profiles, transverse and longitudinal, finding that the recall efficiency can be as large as unity and that the quantum information encoded into the photonic qubits can remain unperturbed. Our results provide insight into reversible light-atom interaction and are interesting in view of future quantum communication networks, where pulse compression and decompression may play an important role in increasing the qubit rate or in mapping quantum information from photonic carriers with large optical bandwidth into atomic memories with smaller bandwidth.
NASA Astrophysics Data System (ADS)
Moiseev, S. A.; Tittel, W.
2010-07-01
We study quantum compression and decompression of light pulses that carry quantum information using a photon-echo quantum memory technique with controllable inhomogeneous broadening of an isolated atomic absorption line. We investigate media with differently broadened absorption profiles, transverse and longitudinal, finding that the recall efficiency can be as large as unity and that the quantum information encoded into the photonic qubits can remain unperturbed. Our results provide insight into reversible light-atom interaction and are interesting in view of future quantum communication networks, where pulse compression and decompression may play an important role in increasing the qubit rate or in mapping quantum information from photonic carriers with large optical bandwidth into atomic memories with smaller bandwidth.
A quantum phase switch between a single solid-state spin and a photon.
Sun, Shuo; Kim, Hyochul; Solomon, Glenn S; Waks, Edo
2016-06-01
Interactions between single spins and photons are essential for quantum networks and distributed quantum computation. Achieving spin-photon interactions in a solid-state device could enable compact chip-integrated quantum circuits operating at gigahertz bandwidths. Many theoretical works have suggested using spins embedded in nanophotonic structures to attain this high-speed interface. These proposals implement a quantum switch where the spin flips the state of the photon and a photon flips the spin state. However, such a switch has not yet been realized using a solid-state spin system. Here, we report an experimental realization of a spin-photon quantum switch using a single solid-state spin embedded in a nanophotonic cavity. We show that the spin state strongly modulates the polarization of a reflected photon, and a single reflected photon coherently rotates the spin state. These strong spin-photon interactions open up a promising direction for solid-state implementations of high-speed quantum networks and on-chip quantum information processors using nanophotonic devices. PMID:26854569
A quantum phase switch between a single solid-state spin and a photon
NASA Astrophysics Data System (ADS)
Sun, Shuo; Kim, Hyochul; Solomon, Glenn S.; Waks, Edo
2016-06-01
Interactions between single spins and photons are essential for quantum networks and distributed quantum computation. Achieving spin–photon interactions in a solid-state device could enable compact chip-integrated quantum circuits operating at gigahertz bandwidths. Many theoretical works have suggested using spins embedded in nanophotonic structures to attain this high-speed interface. These proposals implement a quantum switch where the spin flips the state of the photon and a photon flips the spin state. However, such a switch has not yet been realized using a solid-state spin system. Here, we report an experimental realization of a spin–photon quantum switch using a single solid-state spin embedded in a nanophotonic cavity. We show that the spin state strongly modulates the polarization of a reflected photon, and a single reflected photon coherently rotates the spin state. These strong spin–photon interactions open up a promising direction for solid-state implementations of high-speed quantum networks and on-chip quantum information processors using nanophotonic devices.
Infrared transparent graphene heater for silicon photonic integrated circuits.
Schall, Daniel; Mohsin, Muhammad; Sagade, Abhay A; Otto, Martin; Chmielak, Bartos; Suckow, Stephan; Giesecke, Anna Lena; Neumaier, Daniel; Kurz, Heinrich
2016-04-18
Thermo-optical tuning of the refractive index is one of the pivotal operations performed in integrated silicon photonic circuits for thermal stabilization, compensation of fabrication tolerances, and implementation of photonic operations. Currently, heaters based on metal wires provide the temperature control in the silicon waveguide. The strong interaction of metal and light, however, necessitates a certain gap between the heater and the photonic structure to avoid significant transmission loss. Here we present a graphene heater that overcomes this constraint and enables an energy efficient tuning of the refractive index. We achieve a tuning power as low as 22 mW per free spectral range and fast response time of 3 µs, outperforming metal based waveguide heaters. Simulations support the experimental results and suggest that for graphene heaters the spacing to the silicon can be further reduced yielding the best possible energy efficiency and operation speed. PMID:27137229
Microwave cavity lattices for quantum simulation with photons
NASA Astrophysics Data System (ADS)
Underwood, Devin Lane
Historically our understanding of the microscopic world has been impeded by limitations in systems that behave classically. Even today, understanding simple problems in quantum mechanics remains a difficult task both computationally and experimentally. As a means of overcoming these classical limitations, the idea of using a controllable quantum system to simulate a less controllable quantum system has been proposed. This concept is known as quantum simulation and is the origin of the ideas behind quantum computing. In this thesis, experiments have been conducted that address the feasibility of using devices with a circuit quantum electrodynamics (cQED) architecture as a quantum simulator. In a cQED device, a superconducting qubit is capacitively coupled to a superconducting resonator resulting in coherent quantum behavior of the qubit when it interacts with photons inside the resonator. It has been shown theoretically that by forming a lattice of cQED elements, different quantum phases of photons will exist for dierent system parameters. In order to realize such a quantum simulator, the necessary experimental foundation must rst be developed. Here experimental eorts were focused on addressing two primary issues: 1) designing and fabricating low disorder lattices that are readily available to incorporate superconducting qubits, and 2) developing new measurement tools and techniques that can be used to characterize large lattices, and probe the predicted quantum phases within the lattice. Three experiments addressing these issues were performed. In the rst experiment a Kagome lattice of transmission line resonators was designed and fabricated, and a comprehensive study on the effects of random disorder in the lattice demonstrated that disorder was dependent on the resonator geometry. Subsequently a cryogenic 3-axis scanning stage was developed and the operation of the scanning stage was demonstrated in the final two experiments. The rst scanning experiment was
NASA Astrophysics Data System (ADS)
Luo, Ming-Xing; Li, Hui-Ran; Lai, Hong
2016-07-01
Most of previous quantum computations only take use of one degree of freedom (DoF) of photons. An experimental system may possess various DoFs simultaneously. In this paper, with the weak cross-Kerr nonlinearity, we investigate the parallel quantum computation dependent on photonic systems with two DoFs. We construct nearly deterministic controlled-not (CNOT) gates operating on the polarization spatial DoFs of the two-photon or one-photon system. These CNOT gates show that two photonic DoFs can be encoded as independent qubits without auxiliary DoF in theory. Only the coherent states are required. Thus one half of quantum simulation resources may be saved in quantum applications if more complicated circuits are involved. Hence, one may trade off the implementation complexity and simulation resources by using different photonic systems. These CNOT gates are also used to complete various applications including the quantum teleportation and quantum superdense coding.
Individual carbon nanotubes for quantum electronic and quantum photonic devices
NASA Astrophysics Data System (ADS)
Ai, Nan
2011-12-01
Carbon nanotubes (CNTs) are promising materials since their unique one dimensional geometry leads to remarkable physical properties such as ballistic transport, long mean free path, large direct band gaps, high mechanical tensile strength and strong exciton binding energies, which make them attractive candidates for applications in high-performance nanoelectronics and nanophotonics. CNT-based field-effect transistors (CNT-FETs) are considered to be ideally suited for future nanoelectronics. Single CNT-FETs made by depositing metal electrodes on top of individual CNTs with E-beam lithography have achieved great performance but are limited for massive large area integrated circuit fabrication. Therefore, this thesis demonstrates characteristics of CNT-FETs made by registered in-plane growth utilizing tailored nanoscale catalyst patterns and chemical vapor deposition (CVD), resulting in CNT arrays directly bridging source and drain. The demonstrated access to individual CNTs with pronounced semiconducting behavior opens also the possibility to form more advanced nanoelectronic structures such as CNT quantum dots. CNT-based single electron transistors (CNT-SETS) are promising for quantum electronic devices operating with ultra-low power consumption and allow fundamental studies of electron transport. In addition to existing CNT-SETS based on individual CNTs, we have fabricated the first CNT-SETS based on in-plane grown CNTs using the CVD technique. The demonstrated utilization of registered in-plane growth opens possibilities to create novel SET device geometries which are more complex, i.e. laterally ordered and scalable, as required for advanced quantum electronic devices. Blinking and spectral diffusion are hallmarks of nanoscale light emitters and a challenge for creating stable fluorescent biomarkers or efficient nonclassical light sources. The studies of blinking of CNTs are still in the explorative stage. In this thesis, I show the first experimental
Chapter 12: Trapped Electrons as Electrical (Quantum) Circuits
NASA Astrophysics Data System (ADS)
Verdú, José
2014-01-01
In this chapter, we present a detailed model of the equivalent electric circuit of a single trapped particle in a coplanar-waveguide (CPW) Penning trap. The CPW-trap, which is essentially a section of coplanar-waveguide transmission-line, is designed to make it compatible with circuit-quantum electrodynamic architectures. This will enable a single trapped electron, or geonium atom, as a potential building block of microwave quantum circuits. The model of the trapped electron as an electric circuit was first introduced by Hans Dehmelt in the 1960s. It is essential for the description of the electronic detection using resonant tank circuits. It is also the basis for the description of the interaction of a geonium atom with other distant quantum systems through electrical (microwave) signals.
InP-based three-dimensional photonic integrated circuits
NASA Astrophysics Data System (ADS)
Tsou, Diana; Zaytsev, Sergey; Pauchard, Alexandre; Hummel, Steve; Lo, Yu-Hwa
2001-10-01
Fast-growing internet traffic volumes require high data communication bandwidth over longer distances than short wavelength (850 nm) multi-mode fiber systems can provide. Access network bottlenecks put pressure on short-range (SR) telecommunication systems. To effectively address these datacom and telecom market needs, low cost, high-speed laser modules at 1310 and 1550 nm wavelengths are required. The great success of GaAs 850 nm VCSELs for Gb/s Ethernet has motivated efforts to extend VCSEL technology to longer wavelengths in the 1310 and 1550 nm regimes. However, the technological challenges associated with available intrinsic materials for long wavelength VCSELs are tremendous. Even with recent advances in this area, it is believed that significant additional development is necessary before long wavelength VCSELs that meet commercial specifications will be widely available. In addition, the more stringent OC192 and OC768 specifications for single-mode fiber (SMF) datacom may require more than just a long wavelength laser diode, VCSEL or not, to address numerous cost and performance issues. We believe that photonic integrated circuits, which compactly integrate surface-emitting lasers with additional active and passive optical components with extended functionality, will provide the best solutions to today's problems. Photonic integrated circuits (PICs) have been investigated for more than a decade. However, they have produced limited commercial impact to date primarily because the highly complicated fabrication processes produce significant yield and device performance issues. In this presentation, we will discuss a new technology platform for fabricating InP-based photonic integrated circuits compatible with surface-emitting laser technology. Employing InP transparency at 1310 and 1550 nm wavelengths, we have created 3-D photonic integrated circuits (PICs) by utilizing light beams in both surface normal and in-plane directions within the InP-based structure
Photonic Quantum Networks formed from NV− centers
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.
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 (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. PMID:27215433
Photonic Quantum Networks formed from NV‑ centers
NASA Astrophysics Data System (ADS)
Nemoto, Kae; Trupke, Michael; Devitt, Simon J.; Scharfenberger, Burkhard; Buczak, Kathrin; Schmiedmayer, Jörg; Munro, William J.
2016-05-01
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.
Local Random Quantum Circuits are Approximate Polynomial-Designs
NASA Astrophysics Data System (ADS)
Brandão, Fernando G. S. L.; Harrow, Aram W.; Horodecki, Michał
2016-08-01
We prove that local random quantum circuits acting on n qubits composed of O(t 10 n 2) many nearest neighbor two-qubit gates form an approximate unitary t-design. Previously it was unknown whether random quantum circuits were a t-design for any t > 3. The proof is based on an interplay of techniques from quantum many-body theory, representation theory, and the theory of Markov chains. In particular we employ a result of Nachtergaele for lower bounding the spectral gap of frustration-free quantum local Hamiltonians; a quasi-orthogonality property of permutation matrices; a result of Oliveira which extends to the unitary group the path-coupling method for bounding the mixing time of random walks; and a result of Bourgain and Gamburd showing that dense subgroups of the special unitary group, composed of elements with algebraic entries, are ∞-copy tensor-product expanders. We also consider pseudo-randomness properties of local random quantum circuits of small depth and prove that circuits of depth O(t 10 n) constitute a quantum t-copy tensor-product expander. The proof also rests on techniques from quantum many-body theory, in particular on the detectability lemma of Aharonov, Arad, Landau, and Vazirani. We give applications of the results to cryptography, equilibration of closed quantum dynamics, and the generation of topological order. In particular we show the following pseudo-randomness property of generic quantum circuits: Almost every circuit U of size O(n k ) on n qubits cannot be distinguished from a Haar uniform unitary by circuits of size O(n (k-9)/11) that are given oracle access to U.
Basic structures of integrated photonic circuits for smart biosensor applications
NASA Astrophysics Data System (ADS)
Germer, S.; Cherkouk, C.; Rebohle, L.; Helm, M.; Skorupa, W.
2013-05-01
The breadth of opportunities for applied technologies for optical sensors ranges from environmental and biochemical control, medical diagnostics to process regulation. Thus the specified usage of the optical sensor system requires a particular design and functionalization. Especially biochemical sensors incorporate electronic and photonic devices for the detection of harmful substances e.g. in drinking water. Here we present recent developments in the integration of a Si-based light emitting device (LED) [1-3, 8] into a photonic circuit for an optical waveguide-based biodetection system. This concept includes the design, fabrication and characterization of the dielectric high contrast waveguide as an important component, beside the LED, in the photonic system circuit. First approaches involve simulations of Si3N4/SiO2-waveguides with the finite element method (FEM) and their fabrication by plasma enhanced chemical vapour deposition (PECVD), optical lithography and reactive ion etching (RIE). In addition, we characterized the deposited layers via ellipsometry and the etched structures by scanning electron microscopy (SEM). The obtained results establish a basis for optimized Si-based LED waveguide butt-coupling with adequate coupling efficiency, low attenuation loss and a high optical power throughput.
Quantum circuit for optimal eavesdropping in quantum key distribution using phase-time coding
Kronberg, D. A.; Molotkov, S. N.
2010-07-15
A quantum circuit is constructed for optimal eavesdropping on quantum key distribution proto- cols using phase-time coding, and its physical implementation based on linear and nonlinear fiber-optic components is proposed.
Photonic crystal ring resonator based optical filters for photonic integrated circuits
Robinson, S.
2014-10-15
In this paper, a two Dimensional (2D) Photonic Crystal Ring Resonator (PCRR) based optical Filters namely Add Drop Filter, Bandpass Filter, and Bandstop Filter are designed for Photonic Integrated Circuits (PICs). The normalized output response of the filters is obtained using 2D Finite Difference Time Domain (FDTD) method and the band diagram of periodic and non-periodic structure is attained by Plane Wave Expansion (PWE) method. The size of the device is minimized from a scale of few tens of millimeters to the order of micrometers. The overall size of the filters is around 11.4 μm × 11.4 μm which is highly suitable of photonic integrated circuits.
On-chip electrically controlled routing of photons from a single quantum dot
Bentham, C.; Coles, R. J.; Royall, B.; O'Hara, J.; Prtljaga, N.; Fox, A. M.; Skolnick, M. S.; Wilson, L. R.; Itskevich, I. E.; Clarke, E.
2015-06-01
Electrical control of on-chip routing of photons emitted by a single InAs/GaAs self-assembled quantum dot (SAQD) is demonstrated in a photonic crystal cavity-waveguide system. The SAQD is located inside an H1 cavity, which is coupled to two photonic crystal waveguides. The SAQD emission wavelength is electrically tunable by the quantum-confined Stark effect. When the SAQD emission is brought into resonance with one of two H1 cavity modes, it is preferentially routed to the waveguide to which that mode is selectively coupled. This proof of concept provides the basis for scalable, low-power, high-speed operation of single-photon routers for use in integrated quantum photonic circuits.
NASA Astrophysics Data System (ADS)
Vuckovic, Jelena
2009-05-01
Quantum dots in photonic crystals are interesting both as a testbed for fundamental cavity quantum electrodynamics (QED) experiments, as well as a platform for quantum and classical information processing. Quantum dot-photonic crystal cavity QED has been probed both in photoluminescence and coherently, by resonant light scattering from such a system [1]. In the latter case, both intensity and photon statistics of the reflected beam have been analyzed as a function of wavelength, leading to observation of effects such as photon blockade and photon induced tunneling - for the first time in solid state [2]. The system has also been employed to achieve a controlled phase and amplitude modulation between two modes of light at the single photon level [3] - nonlinearity observed so far only in atomic physics systems. These demonstrations lie at the core of a number of proposals for quantum information processing, and could also be employed to build novel devices, such as optical switches controlled at a single photon level. [4pt] [1] Dirk Englund, Andrei Faraon, Ilya Fushman, Nick Stoltz, Pierre Petroff, and Jelena Vuckovic, ``Controlling cavity reflectivity with a single quantum dot," Nature ,ol. 450, No. 7171, pp. 857-861, December 2007[0pt] [2] Andrei Faraon, Ilya Fushman, Dirk Englund, Nick Stoltz, Pierre Petroff, and Jelena Vuckovic, ``Coherent generation of nonclassical light on a chip via photon-induced tunneling and blockade," Nature Physics ,ol. 4, pp. 859 - 863 (2008)[0pt] [3] Ilya Fushman, Dirk Englund, Andrei Faraon, Nick Stoltz, Pierre Petroff, and Jelena Vuckovic, ``Controlled phase shift with a single quantum dot," Science ,ol. 320, number 5877, pp. 769-772 ( 2008)
Intrusion Detection with Quantum Mechanics: A Photonic Quantum Fence
Humble, Travis S; Bennink, Ryan S; Grice, Warren P; Owens, Israel J
2008-01-01
We describe the use of quantum-mechanically entangled photons for sensing intrusions across a physical perimeter. Our approach to intrusion detection uses the no-cloning principle of quantum information science as protection against an intruder s ability to spoof a sensor receiver using a classical intercept-resend attack. We explore the bounds on detection using quantum detection and estimation theory, and we experimentally demonstrate the underlying principle of entanglement-based detection using the visibility derived from polarization-correlation measurements.
Quantum information processing with narrow band two-photon state
NASA Astrophysics Data System (ADS)
Lu, Yajun
Application of quantum sources in communication and information processing are believed to bring a new revolution to the on-going information age. The generation of applicable quantum sources such as single photon state and two-photon state, appears to be one of the most difficult in experimental quantum optics. Spontaneous Parametric Down-Conversion (PDC) is known to generate two-photon state, but bandwidth problem makes it less applicable in quantum information processing. The aim of this work is to generate a narrow band two-photon state and apply it to quantum information processing. We start by developing a cavity enhanced PDC device to narrow the bandwidth of the two-photon state. Direct measurement of the bandwidth of the generated state has been made and the quantum theory of such a device has been investigated. An application of this narrow band two-photon state is to generate anti-bunched photons for quantum cryptography, based on the quantum interference between the two-photon state and a coherent state. The feasibility of this scheme for pulsed pump is also investigated. When applying the concept of mode locking in lasers to a two-photon state, we have mode-locked two-photon state which exhibits a comb-like correlation function and may be used for engineering of quantum states in time domain. Other applications such as demonstration of single photon nonlocality, nonlinear sign gate in quantum computation, and direct measurement of quantum beating, will also be addressed.
Efficient quantum circuits for Toeplitz and Hankel matrices
NASA Astrophysics Data System (ADS)
Mahasinghe, A.; Wang, J. B.
2016-07-01
Toeplitz and Hankel matrices have been a subject of intense interest in a wide range of science and engineering related applications. In this paper, we show that quantum circuits can efficiently implement sparse or Fourier-sparse Toeplitz and Hankel matrices. This provides an essential ingredient for solving many physical problems with Toeplitz or Hankel symmetry in the quantum setting with deterministic queries.
Ion photon networks for quantum computing and quantum repeaters
NASA Astrophysics Data System (ADS)
Clark, Susan; Hayes, David; Hucul, David; Inlek, I. Volkan; Monroe, Christopher
2013-03-01
Quantum information based on ion-trap technology is well regarded for its stability, high detection fidelity, and ease of manipulation. Here we demonstrate a proof of principle experiment for scaling this technology to large numbers of ions in separate traps by linking the ions via photons. We give results for entanglement between distant ions via probabilistic photonic gates that is then swapped between ions in the same trap via deterministic Coulombic gates. We report fidelities above 65% and show encouraging preliminary results for the next stage of experimental improvement. Such a system could be used for quantum computing requiring large numbers of qubits or for quantum repeaters requiring the qubits to be separated by large distances.
NASA Astrophysics Data System (ADS)
Castelletto, S. A.; Scholten, R. E.
2008-03-01
Single photon counting, based on single photon sources and detectors, is a key ingredient for certain applications aiming at new quantum information technologies. Quantum cryptography, quantum radiometry, distributed quantum computing, as well as adjacent technologies such as biomedical and astronomical imaging, and low power classical communication also rely on single-photon technology. This paper reviews the present status of single photon sources and related counting measurement techniques, based on correlated (or heralded) photons in parametric down-conversion, and their possible impact on the above mentioned technologies, as well as an assessment for photon standards in the future.
Heralded photon amplification for quantum communication
NASA Astrophysics Data System (ADS)
Osorio, C. I.; Bruno, N.; Sangouard, N.; Zbinden, H.; Gisin, N.; Thew, R. T.
2012-08-01
Heralded noiseless amplification based on single-photon sources and linear optics is ideally suited for long-distance quantum communication tasks based on discrete variables. We experimentally demonstrate such an amplifier, operating at telecommunication wavelengths. Coherent amplification is performed with a gain of G=1.98±0.20 for a state with a maximum expected gain G=2. We also demonstrate that there is no need for a stable phase reference between the initial signal state and the local auxiliary photons used by the amplifier. We discuss these results in the context of experimental device-independent quantum key distribution based on heralded qubit amplification, and we highlight several key challenges for its realization.
Advances in integrated photonic circuits for packet-switched interconnection
NASA Astrophysics Data System (ADS)
Williams, Kevin A.; Stabile, Ripalta
2014-03-01
Sustained increases in capacity and connectivity are needed to overcome congestion in a range of broadband communication network nodes. Packet routing and switching in the electronic domain are leading to unsustainable energy- and bandwidth-densities, motivating research into hybrid solutions: optical switching engines are introduced for massive-bandwidth data transport while the electronic domain is clocked at more modest GHz rates to manage routing. Commercially-deployed optical switching engines using MEMS technologies are unwieldy and too slow to reconfigure for future packet-based networking. Optoelectronic packet-compliant switch technologies have been demonstrated as laboratory prototypes, but they have so far mostly used discretely pigtailed components, which are impractical for control plane development and product assembly. Integrated photonics has long held the promise of reduced hardware complexity and may be the critical step towards packet-compliant optical switching engines. Recently a number of laboratories world-wide have prototyped optical switching circuits using monolithic integration technology with up to several hundreds of integrated optical components per chip. Our own work has focused on multi-input to multi-output switching matrices. Recently we have demonstrated 8×8×8λ space and wavelength selective switches using gated cyclic routers and 16×16 broadband switching chips using monolithic multi-stage networks. We now operate these advanced circuits with custom control planes implemented with FPGAs to explore real time packet routing in multi-wavelength, multi-port test-beds. We review our contributions in the context of state of the art photonic integrated circuit technology and packet optical switching hardware demonstrations.
Quantum Logic with Cavity Photons From Single Atoms.
Holleczek, Annemarie; Barter, Oliver; Rubenok, Allison; Dilley, Jerome; Nisbet-Jones, Peter B R; Langfahl-Klabes, Gunnar; Marshall, Graham D; Sparrow, Chris; O'Brien, Jeremy L; Poulios, Konstantinos; Kuhn, Axel; Matthews, Jonathan C F
2016-07-01
We demonstrate quantum logic using narrow linewidth photons that are produced with an a priori nonprobabilistic scheme from a single ^{87}Rb atom strongly coupled to a high-finesse cavity. We use a controlled-not gate integrated into a photonic chip to entangle these photons, and we observe nonclassical correlations between photon detection events separated by periods exceeding the travel time across the chip by 3 orders of magnitude. This enables quantum technology that will use the properties of both narrow-band single photon sources and integrated quantum photonics. PMID:27447506
Quantum Logic with Cavity Photons From Single Atoms
NASA Astrophysics Data System (ADS)
Holleczek, Annemarie; Barter, Oliver; Rubenok, Allison; Dilley, Jerome; Nisbet-Jones, Peter B. R.; Langfahl-Klabes, Gunnar; Marshall, Graham D.; Sparrow, Chris; O'Brien, Jeremy L.; Poulios, Konstantinos; Kuhn, Axel; Matthews, Jonathan C. F.
2016-07-01
We demonstrate quantum logic using narrow linewidth photons that are produced with an a priori nonprobabilistic scheme from a single 87Rb atom strongly coupled to a high-finesse cavity. We use a controlled-not gate integrated into a photonic chip to entangle these photons, and we observe nonclassical correlations between photon detection events separated by periods exceeding the travel time across the chip by 3 orders of magnitude. This enables quantum technology that will use the properties of both narrow-band single photon sources and integrated quantum photonics.
Information Thermodynamics applied to the MERA quantum circuit
NASA Astrophysics Data System (ADS)
Passias, Vasilios; Chua, Victor; Tiwari, Apoorv; Ryu, Shinsei
We interpret the MERA (Multiscale Entanglement Renormalization Ansatz) tensor network as a unitary quantum circuit to study excited states of quantum spin-chains. Contrary to the common use of MERA as a variational ground state ansatz, the quantum circuit defined by MERA - adapted to a fixed ground state - is employed as a diagnostic tool to study dynamically evolving excited state wavefunctions. Outputs of the quantum computation emanating from the isometry tensors, which are normally approximate tensor product states, now fluctuate strongly. These ``bulk'' degrees of freedom in the MERA which act as logical qubits are studied using tools from quantum information theory and information thermodynamics. A local temperature scale based on Landauer's information erasure principle is defined to measure their degree of fluctuation. We investigate properties of this temperature against the expectations of Luttinger's theorem which relates weak field gravity to heat flow. This work was supported by the Gordon and Betty Moore Foundation.
Quantum nanophotonics: Controlling a photon with a single spin
NASA Astrophysics Data System (ADS)
Waks, Edo
The implementation of quantum network and distributive quantum computation replies on strong interactions between stationary matter qubits and flying photons. The spin of a single electron confined in a quantum dot is considered as a promising matter qubit as it possesses microsecond coherence time and allows picosecond timescale control using optical pulses. The quantum dot spin can also interact with a photon by controlling the optical response of a strongly coupled cavity. In this talk I will discuss our recent work on an experimental realization of a spin-photon quantum phase switch using a single spin in a quantum dot strongly coupled to a photonic crystal cavity. We show large modulation of the cavity reflection spectrum by manipulating the spin states of the quantum dot, which enables us to control the quantum state of a reflected photon. We also show the complementary effect where the presence of a single photon switches the quantum state of the spin. The reported spin-photon quantum phase operation can switch spin or photon states in picoseconds timescale, representing an important step towards GHz semiconductor based quantum logic devices on-a-chip and solid-state implementations of quantum networks. Shuo Sun, Hyochul Kim, Glenn Solomon, co-authors.
NASA Astrophysics Data System (ADS)
Weng, Qianchun; An, Zhenghua; Zhang, Bo; Chen, Pingping; Chen, Xiaoshuang; Zhu, Ziqiang; Lu, Wei
2015-03-01
Low-noise single-photon detectors that can resolve photon numbers are used to monitor the operation of quantum gates in linear-optical quantum computation. Exactly 0, 1 or 2 photons registered in a detector should be distinguished especially in long-distance quantum communication and quantum computation. Here we demonstrate a photon-number-resolving detector based on quantum dot coupled resonant tunneling diodes (QD-cRTD). Individual quantum-dots (QDs) coupled closely with adjacent quantum well (QW) of resonant tunneling diode operate as photon-gated switches- which turn on (off) the RTD tunneling current when they trap photon-generated holes (recombine with injected electrons). Proposed electron-injecting operation fills electrons into coupled QDs which turn ``photon-switches'' to ``OFF'' state and make the detector ready for multiple-photons detection. With proper decision regions defined, 1-photon and 2-photon states are resolved in 4.2 K with excellent propabilities of accuracy of 90% and 98% respectively. Further, by identifying step-like photon responses, the photon-number-resolving capability is sustained to 77 K, making the detector a promising candidate for advanced quantum information applications where photon-number-states should be accurately distinguished.
Weng, Qianchun; An, Zhenghua; Zhang, Bo; Chen, Pingping; Chen, Xiaoshuang; Zhu, Ziqiang; Lu, Wei
2015-01-01
Low-noise single-photon detectors that can resolve photon numbers are used to monitor the operation of quantum gates in linear-optical quantum computation. Exactly 0, 1 or 2 photons registered in a detector should be distinguished especially in long-distance quantum communication and quantum computation. Here we demonstrate a photon-number-resolving detector based on quantum dot coupled resonant tunneling diodes (QD-cRTD). Individual quantum-dots (QDs) coupled closely with adjacent quantum well (QW) of resonant tunneling diode operate as photon-gated switches- which turn on (off) the RTD tunneling current when they trap photon-generated holes (recombine with injected electrons). Proposed electron-injecting operation fills electrons into coupled QDs which turn “photon-switches” to “OFF” state and make the detector ready for multiple-photons detection. With proper decision regions defined, 1-photon and 2-photon states are resolved in 4.2 K with excellent propabilities of accuracy of 90% and 98% respectively. Further, by identifying step-like photon responses, the photon-number-resolving capability is sustained to 77 K, making the detector a promising candidate for advanced quantum information applications where photon-number-states should be accurately distinguished. PMID:25797442
Weng, Qianchun; An, Zhenghua; Zhang, Bo; Chen, Pingping; Chen, Xiaoshuang; Zhu, Ziqiang; Lu, Wei
2015-01-01
Low-noise single-photon detectors that can resolve photon numbers are used to monitor the operation of quantum gates in linear-optical quantum computation. Exactly 0, 1 or 2 photons registered in a detector should be distinguished especially in long-distance quantum communication and quantum computation. Here we demonstrate a photon-number-resolving detector based on quantum dot coupled resonant tunneling diodes (QD-cRTD). Individual quantum-dots (QDs) coupled closely with adjacent quantum well (QW) of resonant tunneling diode operate as photon-gated switches- which turn on (off) the RTD tunneling current when they trap photon-generated holes (recombine with injected electrons). Proposed electron-injecting operation fills electrons into coupled QDs which turn "photon-switches" to "OFF" state and make the detector ready for multiple-photons detection. With proper decision regions defined, 1-photon and 2-photon states are resolved in 4.2 K with excellent propabilities of accuracy of 90% and 98% respectively. Further, by identifying step-like photon responses, the photon-number-resolving capability is sustained to 77 K, making the detector a promising candidate for advanced quantum information applications where photon-number-states should be accurately distinguished. PMID:25797442
Song, Guo-Zhu; Wu, Fang-Zhou; Zhang, Mei; Yang, Guo-Jian
2016-01-01
Quantum repeater is the key element in quantum communication and quantum information processing. Here, we investigate the possibility of achieving a heralded quantum repeater based on the scattering of photons off single emitters in one-dimensional waveguides. We design the compact quantum circuits for nonlocal entanglement generation, entanglement swapping, and entanglement purification, and discuss the feasibility of our protocols with current experimental technology. In our scheme, we use a parametric down-conversion source instead of ideal single-photon sources to realize the heralded quantum repeater. Moreover, our protocols can turn faulty events into the detection of photon polarization, and the fidelity can reach 100% in principle. Our scheme is attractive and scalable, since it can be realized with artificial solid-state quantum systems. With developed experimental technique on controlling emitter-waveguide systems, the repeater may be very useful in long-distance quantum communication. PMID:27350159
NASA Astrophysics Data System (ADS)
Song, Guo-Zhu; Wu, Fang-Zhou; Zhang, Mei; Yang, Guo-Jian
2016-06-01
Quantum repeater is the key element in quantum communication and quantum information processing. Here, we investigate the possibility of achieving a heralded quantum repeater based on the scattering of photons off single emitters in one-dimensional waveguides. We design the compact quantum circuits for nonlocal entanglement generation, entanglement swapping, and entanglement purification, and discuss the feasibility of our protocols with current experimental technology. In our scheme, we use a parametric down-conversion source instead of ideal single-photon sources to realize the heralded quantum repeater. Moreover, our protocols can turn faulty events into the detection of photon polarization, and the fidelity can reach 100% in principle. Our scheme is attractive and scalable, since it can be realized with artificial solid-state quantum systems. With developed experimental technique on controlling emitter-waveguide systems, the repeater may be very useful in long-distance quantum communication.
Song, Guo-Zhu; Wu, Fang-Zhou; Zhang, Mei; Yang, Guo-Jian
2016-01-01
Quantum repeater is the key element in quantum communication and quantum information processing. Here, we investigate the possibility of achieving a heralded quantum repeater based on the scattering of photons off single emitters in one-dimensional waveguides. We design the compact quantum circuits for nonlocal entanglement generation, entanglement swapping, and entanglement purification, and discuss the feasibility of our protocols with current experimental technology. In our scheme, we use a parametric down-conversion source instead of ideal single-photon sources to realize the heralded quantum repeater. Moreover, our protocols can turn faulty events into the detection of photon polarization, and the fidelity can reach 100% in principle. Our scheme is attractive and scalable, since it can be realized with artificial solid-state quantum systems. With developed experimental technique on controlling emitter-waveguide systems, the repeater may be very useful in long-distance quantum communication. PMID:27350159
Digital quantum simulation of fermionic models with a superconducting circuit
NASA Astrophysics Data System (ADS)
Barends, R.; Lamata, L.; Kelly, J.; García-Álvarez, L.; Fowler, A. G.; Megrant, A.; Jeffrey, E.; White, T. C.; Sank, D.; Mutus, J. Y.; Campbell, B.; Chen, Yu; Chen, Z.; Chiaro, B.; Dunsworth, A.; Hoi, I.-C.; Neill, C.; O'Malley, P. J. J.; Quintana, C.; Roushan, P.; Vainsencher, A.; Wenner, J.; Solano, E.; Martinis, John M.
2015-07-01
One of the key applications of quantum information is simulating nature. Fermions are ubiquitous in nature, appearing in condensed matter systems, chemistry and high energy physics. However, universally simulating their interactions is arguably one of the largest challenges, because of the difficulties arising from anticommutativity. Here we use digital methods to construct the required arbitrary interactions, and perform quantum simulation of up to four fermionic modes with a superconducting quantum circuit. We employ in excess of 300 quantum logic gates, and reach fidelities that are consistent with a simple model of uncorrelated errors. The presented approach is in principle scalable to a larger number of modes, and arbitrary spatial dimensions.
Digital quantum simulation of fermionic models with a superconducting circuit.
Barends, R; Lamata, L; Kelly, J; García-Álvarez, L; Fowler, A G; Megrant, A; Jeffrey, E; White, T C; Sank, D; Mutus, J Y; Campbell, B; Chen, Yu; Chen, Z; Chiaro, B; Dunsworth, A; Hoi, I-C; Neill, C; O'Malley, P J J; Quintana, C; Roushan, P; Vainsencher, A; Wenner, J; Solano, E; Martinis, John M
2015-01-01
One of the key applications of quantum information is simulating nature. Fermions are ubiquitous in nature, appearing in condensed matter systems, chemistry and high energy physics. However, universally simulating their interactions is arguably one of the largest challenges, because of the difficulties arising from anticommutativity. Here we use digital methods to construct the required arbitrary interactions, and perform quantum simulation of up to four fermionic modes with a superconducting quantum circuit. We employ in excess of 300 quantum logic gates, and reach fidelities that are consistent with a simple model of uncorrelated errors. The presented approach is in principle scalable to a larger number of modes, and arbitrary spatial dimensions. PMID:26153660
Quantum chemistry and charge transport in biomolecules with superconducting circuits
García-Álvarez, L.; Las Heras, U.; Mezzacapo, A.; Sanz, M.; Solano, E.; Lamata, L.
2016-01-01
We propose an efficient protocol for digital quantum simulation of quantum chemistry problems and enhanced digital-analog quantum simulation of transport phenomena in biomolecules with superconducting circuits. Along these lines, we optimally digitize fermionic models of molecular structure with single-qubit and two-qubit gates, by means of Trotter-Suzuki decomposition and Jordan-Wigner transformation. Furthermore, we address the modelling of system-environment interactions of biomolecules involving bosonic degrees of freedom with a digital-analog approach. Finally, we consider gate-truncated quantum algorithms to allow the study of environmental effects. PMID:27324814
Quantum chemistry and charge transport in biomolecules with superconducting circuits
NASA Astrophysics Data System (ADS)
García-Álvarez, L.; Las Heras, U.; Mezzacapo, A.; Sanz, M.; Solano, E.; Lamata, L.
2016-06-01
We propose an efficient protocol for digital quantum simulation of quantum chemistry problems and enhanced digital-analog quantum simulation of transport phenomena in biomolecules with superconducting circuits. Along these lines, we optimally digitize fermionic models of molecular structure with single-qubit and two-qubit gates, by means of Trotter-Suzuki decomposition and Jordan-Wigner transformation. Furthermore, we address the modelling of system-environment interactions of biomolecules involving bosonic degrees of freedom with a digital-analog approach. Finally, we consider gate-truncated quantum algorithms to allow the study of environmental effects.
Quantum chemistry and charge transport in biomolecules with superconducting circuits.
García-Álvarez, L; Las Heras, U; Mezzacapo, A; Sanz, M; Solano, E; Lamata, L
2016-01-01
We propose an efficient protocol for digital quantum simulation of quantum chemistry problems and enhanced digital-analog quantum simulation of transport phenomena in biomolecules with superconducting circuits. Along these lines, we optimally digitize fermionic models of molecular structure with single-qubit and two-qubit gates, by means of Trotter-Suzuki decomposition and Jordan-Wigner transformation. Furthermore, we address the modelling of system-environment interactions of biomolecules involving bosonic degrees of freedom with a digital-analog approach. Finally, we consider gate-truncated quantum algorithms to allow the study of environmental effects. PMID:27324814
Solving search problems by strongly simulating quantum circuits
Johnson, T. H.; Biamonte, J. D.; Clark, S. R.; Jaksch, D.
2013-01-01
Simulating quantum circuits using classical computers lets us analyse the inner workings of quantum algorithms. The most complete type of simulation, strong simulation, is believed to be generally inefficient. Nevertheless, several efficient strong simulation techniques are known for restricted families of quantum circuits and we develop an additional technique in this article. Further, we show that strong simulation algorithms perform another fundamental task: solving search problems. Efficient strong simulation techniques allow solutions to a class of search problems to be counted and found efficiently. This enhances the utility of strong simulation methods, known or yet to be discovered, and extends the class of search problems known to be efficiently simulable. Relating strong simulation to search problems also bounds the computational power of efficiently strongly simulable circuits; if they could solve all problems in P this would imply that all problems in NP and #P could be solved in polynomial time. PMID:23390585
Photonic integrated circuits based on novel glass waveguides and devices
NASA Astrophysics Data System (ADS)
Zhang, Yaping; Zhang, Deng; Pan, Weijian; Rowe, Helen; Benson, Trevor; Loni, Armando; Sewell, Phillip; Furniss, David; Seddon, Angela B.
2006-04-01
Novel materials, micro-, nano-scale photonic devices, and 'photonic systems on a chip' have become important focuses for global photonics research and development. This interest is driven by the rapidly growing demand for broader bandwidth in optical communication networks, and higher connection density in the interconnection area, as well as a wider range of application areas in, for example, health care, environment monitoring and security. Taken together, chalcogenide, heavy metal fluoride and fluorotellurite glasses offer transmission from ultraviolet to mid-infrared, high optical non-linearity and the ability to include active dopants, offering the potential for developing optical components with a wide range of functionality. Moreover, using single-mode large cross-section glass-based waveguides as an optical integration platform is an elegant solution for the monolithic integration of optical components, in which the glass-based structures act both as waveguides and as an optical bench for integration. We have previously developed a array of techniques for making photonic integrated circuits and devices based on novel glasses. One is fibre-on-glass (FOG), in which the fibres can be doped with different active dopants and pressed onto a glass substrate with a different composition using low-temperature thermal bonding under mechanical compression. Another is hot-embossing, in which a silicon mould is placed on top of a glass sample, and hot-embossing is carried out by applying heat and pressure. In this paper the development of a fabrication technique that combines the FOG and hot-embossing procedures to good advantage is described. Simulation and experimental results are presented.
Telegraph noise in coupled quantum dot circuits induced by a quantum point contact.
Taubert, D; Pioro-Ladrière, M; Schröer, D; Harbusch, D; Sachrajda, A S; Ludwig, S
2008-05-01
Charge detection utilizing a highly biased quantum point contact has become the most effective probe for studying few electron quantum dot circuits. Measurements on double and triple quantum dot circuits is performed to clarify a back action role of charge sensing on the confined electrons. The quantum point contact triggers inelastic transitions, which occur quite generally. Under specific device and measurement conditions these transitions manifest themselves as bounded regimes of telegraph noise within a stability diagram. A nonequilibrium transition from artificial atomic to molecular behavior is identified. Consequences for quantum information applications are discussed. PMID:18518321
Observation of strongly entangled photon pairs from a nanowire quantum dot
Versteegh, Marijn A. M.; Reimer, Michael E.; Jöns, Klaus D.; Dalacu, Dan; Poole, Philip J.; Gulinatti, Angelo; Giudice, Andrea; Zwiller, Val
2014-01-01
A bright photon source that combines high-fidelity entanglement, on-demand generation, high extraction efficiency, directional and coherent emission, as well as position control at the nanoscale is required for implementing ambitious schemes in quantum information processing, such as that of a quantum repeater. Still, all of these properties have not yet been achieved in a single device. Semiconductor quantum dots embedded in nanowire waveguides potentially satisfy all of these requirements; however, although theoretically predicted, entanglement has not yet been demonstrated for a nanowire quantum dot. Here, we demonstrate a bright and coherent source of strongly entangled photon pairs from a position-controlled nanowire quantum dot with a fidelity as high as 0.859±0.006 and concurrence of 0.80±0.02. The two-photon quantum state is modified via the nanowire shape. Our new nanoscale entangled photon source can be integrated at desired positions in a quantum photonic circuit, single-electron devices and light-emitting diodes. PMID:25358656
Quantum Circuits for Measuring Levin-Wen Operators
NASA Astrophysics Data System (ADS)
Bonesteel, Nick; Divincenzo, David
2012-02-01
We give explicit quantum circuits (expressed in terms of Toffoli gates, CNOTs and single qubit rotations) which can be used to perform quantum non-demolition measurements of the commuting set of vertex and plaquette operators that appear in the Levin-Wen model [1] for the case of doubled Fibonacci anyons. Such measurements can be viewed as syndrome measurements for the quantum error correcting code defined by the ground states of the Levin-Wen model --- a scenario envisioned in [2]. A key component in our construction is a quantum circuit F that acts on 5 qubits at a time and carries out a so-called F-move, a unitary operation whose form is essentially fixed by a self-consistency condition known as the pentagon equation. In addition to our measurement circuits we also give an explicit 7 qubit circuit which can be used to verify that F satisfies the full pentagon equation as well as a simpler 2 qubit circuit which verifies the essential nontrivial content of this equation. [1] M.A. Levin and X.-G. Wen, Phys. Rev. B 71 045110 (2005). [2] R. Koenig, G. Kuperberg, and B.W. Reichardt, Ann. Phys 325, 2707 (2010).
Exact quantum Bayesian rule for qubit measurements in circuit QED.
Feng, Wei; Liang, Pengfei; Qin, Lupei; Li, Xin-Qi
2016-01-01
Developing efficient framework for quantum measurements is of essential importance to quantum science and technology. In this work, for the important superconducting circuit-QED setup, we present a rigorous and analytic solution for the effective quantum trajectory equation (QTE) after polaron transformation and converted to the form of Stratonovich calculus. We find that the solution is a generalization of the elegant quantum Bayesian approach developed in arXiv:1111.4016 by Korotokov and currently applied to circuit-QED measurements. The new result improves both the diagonal and off-diagonal elements of the qubit density matrix, via amending the distribution probabilities of the output currents and several important phase factors. Compared to numerical integration of the QTE, the resultant quantum Bayesian rule promises higher efficiency to update the measured state, and allows more efficient and analytical studies for some interesting problems such as quantum weak values, past quantum state, and quantum state smoothing. The method of this work opens also a new way to obtain quantum Bayesian formulas for other systems and in more complicated cases. PMID:26841968
Exact quantum Bayesian rule for qubit measurements in circuit QED
Feng, Wei; Liang, Pengfei; Qin, Lupei; Li, Xin-Qi
2016-01-01
Developing efficient framework for quantum measurements is of essential importance to quantum science and technology. In this work, for the important superconducting circuit-QED setup, we present a rigorous and analytic solution for the effective quantum trajectory equation (QTE) after polaron transformation and converted to the form of Stratonovich calculus. We find that the solution is a generalization of the elegant quantum Bayesian approach developed in arXiv:1111.4016 by Korotokov and currently applied to circuit-QED measurements. The new result improves both the diagonal and off-diagonal elements of the qubit density matrix, via amending the distribution probabilities of the output currents and several important phase factors. Compared to numerical integration of the QTE, the resultant quantum Bayesian rule promises higher efficiency to update the measured state, and allows more efficient and analytical studies for some interesting problems such as quantum weak values, past quantum state, and quantum state smoothing. The method of this work opens also a new way to obtain quantum Bayesian formulas for other systems and in more complicated cases. PMID:26841968
Exact quantum Bayesian rule for qubit measurements in circuit QED
NASA Astrophysics Data System (ADS)
Feng, Wei; Liang, Pengfei; Qin, Lupei; Li, Xin-Qi
2016-02-01
Developing efficient framework for quantum measurements is of essential importance to quantum science and technology. In this work, for the important superconducting circuit-QED setup, we present a rigorous and analytic solution for the effective quantum trajectory equation (QTE) after polaron transformation and converted to the form of Stratonovich calculus. We find that the solution is a generalization of the elegant quantum Bayesian approach developed in arXiv:1111.4016 by Korotokov and currently applied to circuit-QED measurements. The new result improves both the diagonal and off-diagonal elements of the qubit density matrix, via amending the distribution probabilities of the output currents and several important phase factors. Compared to numerical integration of the QTE, the resultant quantum Bayesian rule promises higher efficiency to update the measured state, and allows more efficient and analytical studies for some interesting problems such as quantum weak values, past quantum state, and quantum state smoothing. The method of this work opens also a new way to obtain quantum Bayesian formulas for other systems and in more complicated cases.
Engineering squeezed states of microwave radiation with circuit quantum electrodynamics
Li Pengbo; Li Fuli
2011-03-15
We introduce a squeezed state source for microwave radiation with tunable parameters in circuit quantum electrodynamics. We show that when a superconducting artificial multilevel atom interacting with a transmission line resonator is suitably driven by external classical fields, two-mode squeezed states of the cavity modes can be engineered in a controllable fashion from the vacuum state via adiabatic following of the ground state of the system. This scheme appears to be robust against decoherence and is realizable with present techniques in circuit quantum electrodynamics.
Quantum random number generator using photon-number path entanglement.
Kwon, Osung; Cho, Young-Wook; Kim, Yoon-Ho
2009-03-20
We report a quantum random number generator based on the photon-number-path entangled state that is prepared by means of two-photon quantum interference at a beam splitter. The randomness in our scheme is truly quantum mechanical in origin since it results from the projection measurement of the entangled two-photon state. The generated bit sequences satisfy the standard randomness test. PMID:19305476
Non-Markovian dynamics in chiral quantum networks with spins and photons
NASA Astrophysics Data System (ADS)
Ramos, Tomás; Vermersch, Benoît; Hauke, Philipp; Pichler, Hannes; Zoller, Peter
2016-06-01
We study the dynamics of chiral quantum networks consisting of nodes coupled by unidirectional or asymmetric bidirectional quantum channels. In contrast to familiar photonic networks where driven two-level atoms exchange photons via 1D photonic nanostructures, we propose and study a setup where interactions between the atoms are mediated by spin excitations (magnons) in 1D X X spin chains representing spin waveguides. While Markovian quantum network theory eliminates quantum channels as structureless reservoirs in a Born-Markov approximation to obtain a master equation for the nodes, we are interested in non-Markovian dynamics. This arises from the nonlinear character of the dispersion with band-edge effects, and from finite spin propagation velocities leading to time delays in interactions. To account for the non-Markovian dynamics we treat the quantum degrees of freedom of the nodes and connecting channel as a composite spin system with the surrounding of the quantum network as a Markovian bath, allowing for an efficient solution with time-dependent density matrix renormalization-group techniques. We illustrate our approach showing non-Markovian effects in the driven-dissipative formation of quantum dimers, and we present examples for quantum information protocols involving quantum state transfer with engineered elements as basic building blocks of quantum spintronic circuits.
Improved Classical Simulation of Quantum Circuits Dominated by Clifford Gates.
Bravyi, Sergey; Gosset, David
2016-06-24
We present a new algorithm for classical simulation of quantum circuits over the Clifford+T gate set. The runtime of the algorithm is polynomial in the number of qubits and the number of Clifford gates in the circuit but exponential in the number of T gates. The exponential scaling is sufficiently mild that the algorithm can be used in practice to simulate medium-sized quantum circuits dominated by Clifford gates. The first demonstrations of fault-tolerant quantum circuits based on 2D topological codes are likely to be dominated by Clifford gates due to a high implementation cost associated with logical T gates. Thus our algorithm may serve as a verification tool for near-term quantum computers which cannot in practice be simulated by other means. To demonstrate the power of the new method, we performed a classical simulation of a hidden shift quantum algorithm with 40 qubits, a few hundred Clifford gates, and nearly 50 T gates. PMID:27391708
Quantum structures for multiband photon detection
NASA Astrophysics Data System (ADS)
Perera, A. G. U.
2005-09-01
The work describes multiband photon detectors based on semiconductor micro- and nano-structures. The devices considered include quantum dot, homojunction, and heterojunction structures. In the quantum dot structures, transitions are from one state to another, while free carrier absorption and internal photoemission play the dominant role in homo or heterojunction detectors. Quantum Dots-in-a-Well (DWELL) detectors can tailor the response wavelength by varying the size of the well. A tunneling Quantum Dot Infrared Photodetector (T-QDIP) could operate at room temperature by blocking the dark current except in the case of resonance. Photoexcited carriers are selectively collected from InGaAs quantum dots by resonant tunneling, while the dark current is blocked by AlGaAs/InGaAs tunneling barriers placed in the structure. A two-color infrared detector with photoresponse peaks at ~6 and ~17 μm at room temperature will be discussed. A Homojunction or HEterojunction Interfacial Workfunction Internal Photoemission (HIWIP or HEIWIP) infrared detector, formed by a doped emitter layer, and an intrinsic layer acting as the barrier followed by another highly doped contact layer, can detect near infrared (NIR) photons due to interband transitions and mid/far infrared (MIR/FIR) radiation due to intraband transitions. The threshold wavelength of the interband response depends on the band gap of the barrier material, and the MIR/FIR response due to intraband transitions can be tailored by adjusting the band offset between the emitter and the barrier. GaAs/AlGaAs will provide NIR and MIR/FIR dual band response, and with GaN/AlGaN structures the detection capability can be extended into the ultraviolet region. These detectors are useful in numerous applications such as environmental monitoring, medical diagnosis, battlefield-imaging, space astronomy applications, mine detection, and remote-sensing.
Long-wavelength photonic integrated circuits and avalanche photodetectors
NASA Astrophysics Data System (ADS)
Tsou, Yi-Jen D.; Zaytsev, Sergey; Pauchard, Alexandre; Hummel, Steve; Lo, Yu-Hwa
2001-10-01
Fast-growing internet traffic volume require high data communication bandwidth over longer distances. Access network bottlenecks put pressure on short-range (SR) telecommunication systems. To effectively address these datacom and telecom market needs, low-cost, high-speed laser modules at 1310 to 1550 nm wavelengths and avalanche photodetectors are required. The great success of GaAs 850nm VCSEls for Gb/s Ethernet has motivated efforts to extend VCSEL technology to longer wavelengths in the 1310 and 1550 nm regimes. However, the technological challenges associated with materials for long wavelength VCSELs are tremendous. Even with recent advances in this area, it is believed that significant additional development is necessary before long wavelength VCSELs that meet commercial specifications will be widely available. In addition, the more stringent OC192 and OC768 specifications for single-mode fiber (SMF) datacom may require more than just a long wavelength laser diode, VCSEL or not, to address numerous cost and performance issues. We believe that photonic integrated circuits (PICs), which compactly integrate surface-emitting lasers with additional active and passive optical components with extended functionality, will provide the best solutions to today's problems. Photonic integrated circuits have been investigated for more than a decade. However, they have produced limited commercial impact to date primarily because the highly complicated fabrication processes produce significant yield and device performance issues. In this presentation, we will discuss a new technology platform of InP-based PICs compatible with surface-emitting laser technology, as well as a high data rate externally modulated laser module. Avalanche photodetectors (APDs) are the key component in the receiver to achieve high data rate over long transmission distance because of their high sensitivity and large gain- bandwidth product. We have used wafer fusion technology to achieve In
Entangling distant resonant exchange qubits via circuit quantum electrodynamics
NASA Astrophysics Data System (ADS)
Srinivasa, Vanita; Taylor, Jacob M.; Tahan, Charles
Enabling modularity within a quantum information processing device relies on robust entanglement of coherent qubits at macroscopic distances. To address this challenge, we investigate theoretically a hybrid quantum system consisting of spatially separated resonant exchange qubits, defined in three-electron semiconductor triple quantum dots, that are coupled via a superconducting transmission line resonator. By analyzing three specific approaches drawn from circuit quantum electrodynamics and Hartmann-Hahn double resonance techniques for implementing resonator-mediated two-qubit entangling gates in both dispersive and resonant regimes, we show that methods for entangling superconducting qubits map directly to resonant exchange qubits. We also calculate the rate of relaxation via phonons for resonant exchange qubits in silicon triple dots and show that such an implementation is particularly well-suited to achieving the strong coupling regime. Our approach combines the robustness of encoded spin qubits in silicon with the rapid and robust long-range entanglement provided by circuit QED systems.
Derandomizing Quantum Circuits with Measurement-Based Unitary Designs
NASA Astrophysics Data System (ADS)
Turner, Peter S.; Markham, Damian
2016-05-01
Entangled multipartite states are resources for universal quantum computation, but they can also give rise to ensembles of unitary transformations, a topic usually studied in the context of random quantum circuits. Using several graph state techniques, we show that these resources can "derandomize" circuit results by sampling the same kinds of ensembles quantum mechanically, analogously to a quantum random number generator. Furthermore, we find simple examples that give rise to new ensembles whose statistical moments exactly match those of the uniformly random distribution over all unitaries up to order t , while foregoing adaptive feedforward entirely. Such ensembles—known as t designs—often cannot be distinguished from the "truly" random ensemble, and so they find use in many applications that require this implied notion of pseudorandomness.
Derandomizing Quantum Circuits with Measurement-Based Unitary Designs.
Turner, Peter S; Markham, Damian
2016-05-20
Entangled multipartite states are resources for universal quantum computation, but they can also give rise to ensembles of unitary transformations, a topic usually studied in the context of random quantum circuits. Using several graph state techniques, we show that these resources can "derandomize" circuit results by sampling the same kinds of ensembles quantum mechanically, analogously to a quantum random number generator. Furthermore, we find simple examples that give rise to new ensembles whose statistical moments exactly match those of the uniformly random distribution over all unitaries up to order t, while foregoing adaptive feedforward entirely. Such ensembles-known as t designs-often cannot be distinguished from the "truly" random ensemble, and so they find use in many applications that require this implied notion of pseudorandomness. PMID:27258858
Quantum interference with photon pairs created in spatially separated sources
Riedmatten, H. de; Marcikic, I.; Zbinden, H.; Gisin, N.; Tittel, W.
2003-02-01
We report on a quantum interference experiment to probe the coherence between two photons coming from nondegenerate photon pairs at telecom wavelength created in spatially separated sources. The two photons are mixed on a beam splitter and we observe a reduction of up to 84% in the net coincidence count rate when the photons are made indistinguishable. This experiment constitutes an important step towards the realization of quantum teleportation and entanglement swapping with independent sources.
Efficient Synthesis of Universal Repeat-Until-Success Quantum Circuits
NASA Astrophysics Data System (ADS)
Bocharov, Alex; Roetteler, Martin; Svore, Krysta M.
2015-02-01
Recently it was shown that the resources required to implement unitary operations on a quantum computer can be reduced by using probabilistic quantum circuits called repeat-until-success (RUS) circuits. However, the previously best-known algorithm to synthesize a RUS circuit for a given target unitary requires exponential classical runtime. We present a probabilistically polynomial-time algorithm to synthesize a RUS circuit to approximate any given single-qubit unitary to precision ɛ over the Clifford+T basis. Surprisingly, the T count of the synthesized RUS circuit surpasses the theoretical lower bound of 3 log2(1 /ɛ ) that holds for purely unitary single-qubit circuit decomposition. By taking advantage of measurement and an ancilla qubit, RUS circuits achieve an expected T count of 1.15 log2(1 /ɛ ) for single-qubit z rotations. Our method leverages the fact that the set of unitaries implementable by RUS protocols has a higher density in the space of all unitaries compared to the density of purely unitary implementations.
Two-photon holographic optogenetics of neural circuits (Conference Presentation)
NASA Astrophysics Data System (ADS)
Yang, Weijian; Carrillo-Reid, Luis; Peterka, Darcy S.; Yuste, Rafael
2016-03-01
Optical manipulation of in vivo neural circuits with cellular resolution could be important for understanding cortical function. Despite recent progress, simultaneous optogenetic activation with cellular precision has either been limited to 2D planes, or a very small numbers of neurons over a limited volume. Here we demonstrate a novel paradigm for simultaneous 3D activation using a low repetition rate pulse-amplified fiber laser system and a spatial light modulator (SLM) to project 3D holographic excitation patterns on the cortex of mice in vivo for targeted volumetric 3D photoactivation. This method is compatible with two-photon imaging, and enables the simultaneous activation of multiple cells in 3D, using red-shifted opsins, such as C1V1 or ReaChR, while simultaneously imaging GFP-based sensors such as GCaMP6. This all-optical imaging and 3D manipulation approach achieves simultaneous reading and writing of cortical activity, and should be a powerful tool for the study of neuronal circuits.
Electronic-photonic integrated circuits on the CMOS platform
NASA Astrophysics Data System (ADS)
Kimerling, L. C.; Ahn, D.; Apsel, A. B.; Beals, M.; Carothers, D.; Chen, Y.-K.; Conway, T.; Gill, D. M.; Grove, M.; Hong, C.-Y.; Lipson, M.; Liu, J.; Michel, J.; Pan, D.; Patel, S. S.; Pomerene, A. T.; Rasras, M.; Sparacin, D. K.; Tu, K.-Y.; White, A. E.; Wong, C. W.
2006-02-01
The optical components industry stands at the threshold of a major expansion that will restructure its business processes and sustain its profitability for the next three decades. This growth will establish a cost effective platform for the partitioning of electronic and photonic functionality to extend the processing power of integrated circuits. BAE Systems, Lucent Technologies, Massachusetts Institute of Technology, and Applied Wave Research are participating in a high payoff research and development program for the Microsystems Technology Office (MTO) of DARPA. The goal of the program is the development of technologies and design tools necessary to fabricate an application-specific, electronicphotonic integrated circuit (AS-EPIC). As part of the development of this demonstration platform we are exploring selected functions normally associated with the front end of mixed signal receivers such as modulation, detection, and filtering. The chip will be fabricated in the BAE Systems CMOS foundry and at MIT's Microphotonics Center. We will present the latest results on the performance of multi-layer deposited High Index Contrast Waveguides, CMOS compatible modulators and detectors, and optical filter slices. These advances will be discussed in the context of the Communications Technology Roadmap that was recently released by the MIT Microphotonics Center Industry Consortium.
NASA Astrophysics Data System (ADS)
Ang, Kah-Wee; Liow, Tsung-Yang; Yu, Ming-Bin; Fang, Qing; Song, Junfeng; Lo, Guo Q.; Kwong, Dim-Lee
2010-05-01
In this paper, we report our design and fabrication approach towards realizing a monolithic integration of Ge photodetector and Si CMOS circuits on common SOI platform for integrated photonic applications. The approach, based on the Ge-on-SOI technology, enables the realization of high sensitivity and low noise photodetector that is capable of performing efficient optical-to-electrical encoding in the near-infrared wavelengths regime. When operated at a bias of -1.0V, a vertical PIN detector achieved a lower Idark of ~0.57μA as compared to a lateral PIN detector, a value that is below the typical ~1μA upper limit acceptable for high speed receiver design. Very high responsivity of ~0.92A/W was obtained in both detector designs for a wavelength of 1550nm, which corresponds to a quantum efficiency of ~73%. Impulse response measurements showed that a vertical PIN photodetector gives rise to a smaller FWHM of ~24.4ps, which corresponds to a -3dB bandwidth of ~11.3GHz where RC time delay is known to be the dominant factor limiting the speed performance. Eye patterns (PRBS 27-1) measurement further confirms the achievement of high speed and low noise photodetection at a bit-rate of 8.5Gb/s. In addition, we evaluate the DC characteristics of the monolithically fabricated Si CMOS inverter circuit. Excellent transfer and output characteristics were achieved by the integrated CMOS inverter circuits in addition to the well behaved logic functions. We also assess the impact of the additional thermal budget introduced by the Ge epitaxy growth on the threshold voltage variation of the short channel CMOS transistors and discuss the issues and potential for the seamless integration of electronic and photonic integrated circuits.
A Rydberg atom-photon-superconductor quantum interface
NASA Astrophysics Data System (ADS)
Isaacs, J. A.; Booth, D. W.; Beck, M. A.; Pritchard, J. D.; Xia, T.; McDermott, R.; Saffman, M.; UW Hybrid QC Collaboration
2016-05-01
Hybrid quantum computation bridges disparate quantum technologies in order to achieve fast gates with long coherence times. Our implementation combines superconducting circuit-QED with singly trapped Rydberg atoms. Introducing typical AMO techniques into cryogenic environments required the development of several novel approaches that we will discuss in our talk. Our current experiment involves trapping cesium atoms inside a 4 K cryostat, transporting them first horizontally and then vertically up to a superconducting coplanar waveguide resonator. After transport we use a novel two-photon Rydberg excitation via the 6S1 / 2 --> 5D5 / 2 quadrupole transition to enable direct excitation of nP3 / 2 states for strong electric-dipole coupling to the cavity. This excitation scheme significantly reduces the Doppler mismatch compared to previous two-photon excitation schemes to enable high fidelity operations. First optical spectroscopy and Rabi oscillation results will be shown along with microwave cavity coupling data. Experimental and theoretical efforts toward increasing fidelity of our operations by minimizing sensitivity of the Rydberg atoms to stray external electric fields will be discussed. This work is supported by an ARO DURIP award.