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Sample records for single spin control

  1. Quantum Control over Single Spins in Diamond

    NASA Astrophysics Data System (ADS)

    Dobrovitski, V. V.; Fuchs, G. D.; Falk, A. L.; Santori, C.; Awschalom, D. D.

    2013-04-01

    Nitrogen-vacancy (NV) centers in diamond have recently emerged as a unique platform for fundamental studies in quantum information and nanoscience. The special properties of these impurity centers allow robust, room-temperature operation of solid-state qubits and have enabled several remarkable demonstrations in quantum information processing and precision nanoscale sensing. This article reviews the recent advances in magnetic and optical manipulation of the NV center’s quantum spin and their importance for prospective applications. We discuss how quantum control of individual centers can be harnessed for the protection of NV-center spin coherence, for multiqubit quantum operations in the presence of decoherence, and for high-fidelity initialization and readout. We also discuss the progress in resonant optical control, which has led to interfaces between spin and photonic qubits and may lead to spin networks based on diamond photonics. Many of these recently developed diamond-based technologies constitute critical components for the future leap toward practical multiqubit devices.

  2. Feedback control of nuclear spin bath for a single hole spin in a quantum dot

    NASA Astrophysics Data System (ADS)

    Pang, Hongliang; Gong, Zhirui; Yao, Wang

    2014-03-01

    In a semiconductor quantum dot, the nuclear spin bath plays an important role as the ultimate environment of an electron or hole spin at low temperature. Through dynamic nuclear spin polarization driven by an oscillating electric field, we show that feedback controls can be implemented on the nuclear spin bath of a single hole spin. The feedback controls utilize the anisotropic hyperfine interaction between the hole spin and the nuclear spins. The negative feedback can suppress the statistical fluctuations of the nuclear hyperfine field and lead to longer coherence time of the hole spin. Positive feedback can possibly lead to cat like state of nuclear spin bath. The efficiency of the controls schemes is investigated under different parameters and control strategies. The work is supported by the Croucher Foundation under the Croucher Innovation Award, and the Research Grant Council of Hong Kong (HKU706309P, HKU8/CRF/11G).

  3. Heralded Control of Mechanical Motion by Single Spins.

    PubMed

    Rao, D D Bhaktavatsala; Momenzadeh, S Ali; Wrachtrup, Jörg

    2016-08-12

    We propose a method to achieve a high degree of control of nanomechanical oscillators by coupling their mechanical motion to single spins. Manipulating the spin alone and measuring its quantum state heralds the cooling or squeezing of the oscillator even for weak spin-oscillator couplings. We analytically show that the asymptotic behavior of the oscillator is determined by a spin-induced thermal filter function whose overlap with the initial thermal distribution of the oscillator determines its cooling, heating, or squeezing. Counterintuitively, the rate of cooling dependence on the instantaneous thermal occupancy of the oscillator renders robust cooling or squeezing even for high initial temperatures and damping rates. We further estimate how the proposed scheme can be used to control the motion of a thin diamond cantilever by coupling it to its defect centers at low temperature. PMID:27563995

  4. Heralded Control of Mechanical Motion by Single Spins

    NASA Astrophysics Data System (ADS)

    Rao, D. D. Bhaktavatsala; Momenzadeh, S. Ali; Wrachtrup, Jörg

    2016-08-01

    We propose a method to achieve a high degree of control of nanomechanical oscillators by coupling their mechanical motion to single spins. Manipulating the spin alone and measuring its quantum state heralds the cooling or squeezing of the oscillator even for weak spin-oscillator couplings. We analytically show that the asymptotic behavior of the oscillator is determined by a spin-induced thermal filter function whose overlap with the initial thermal distribution of the oscillator determines its cooling, heating, or squeezing. Counterintuitively, the rate of cooling dependence on the instantaneous thermal occupancy of the oscillator renders robust cooling or squeezing even for high initial temperatures and damping rates. We further estimate how the proposed scheme can be used to control the motion of a thin diamond cantilever by coupling it to its defect centers at low temperature.

  5. Quantum control and engineering of single spins in diamond

    NASA Astrophysics Data System (ADS)

    Toyli, David M.

    The past two decades have seen intensive research efforts aimed at creating quantum technologies that leverage phenomena such as coherence and entanglement to achieve device functionalities surpassing those attainable with classical physics. While the range of applications for quantum devices is typically limited by their cryogenic operating temperatures, in recent years point defects in semiconductors have emerged as potential candidates for room temperature quantum technologies. In particular, the nitrogen vacancy (NV) center in diamond has gained prominence for the ability to measure and control its spin under ambient conditions and for its potential applications in magnetic sensing. Here we describe experiments that probe the thermal limits to the measurement and control of single NV centers to identify the origin of the system's unique temperature dependence and that define novel thermal sensing applications for single spins. We demonstrate the optical measurement and coherent control of the spin at temperatures exceeding 600 K and show that its addressability is eventually limited by thermal quenching of the optical spin readout. These measurements provide important information for the electronic structure responsible for the optical spin initialization and readout processes and, moreover, suggest that the coherence of the NV center's spin states could be harnessed for thermometry applications. To that end, we develop novel quantum control techniques that selectively probe thermally induced shifts in the spin resonance frequencies while minimizing the defect's interactions with nearby nuclear spins. We use these techniques to extend the NV center's spin coherence for thermometry by 45-fold to achieve thermal sensitivities approaching 10 mK Hz-1/2 . We show the versatility of these techniques by performing measurements in a range of magnetic environments and at temperatures as high as 500 K. Together with diamond's ideal thermal, mechanical, and chemical

  6. All-electric spin control in interference single electron transistors.

    PubMed

    Donarini, Andrea; Begemann, Georg; Grifoni, Milena

    2009-08-01

    Single particle interference lies at the heart of quantum mechanics. The archetypal double-slit experiment(1) has been repeated with electrons in vacuum(2,3) up to the more massive C(60) molecules.(4) Mesoscopic rings threaded by a magnetic flux provide the solid-state analogues.(5,6) Intramolecular interference has been recently discussed in molecular junctions.(7-11) Here we propose to exploit interference to achieve all-electrical control of a single electron spin in quantum dots, a highly desirable property for spintronics(12-14) and spin-qubit applications.(15-19) The device consists of an interference single electron transistor,(10,11) where destructive interference between orbitally degenerate electronic states produces current blocking at specific bias voltages. We show that in the presence of parallel polarized ferromagnetic leads the interplay between interference and the exchange interaction on the system generates an effective energy renormalization yielding different blocking biases for majority and minority spins. Hence, by tuning the bias voltage full control over the spin of the trapped electron is achieved.

  7. Controlling superconducting spin flow with spin-flip immunity using a single homogeneous ferromagnet

    PubMed Central

    Jacobsen, Sol H.; Kulagina, Iryna; Linder, Jacob

    2016-01-01

    Spin transport via electrons is typically plagued by Joule heating and short decay lengths due to spin-flip scattering. It is known that dissipationless spin currents can arise when using conventional superconducting contacts, yet this has only been experimentally demonstrated when using intricate magnetically inhomogeneous multilayers, or in extreme cases such as half-metals with interfacial magnetic disorder. Moreover, it is unknown how such spin supercurrents decay in the presence of spin-flip scattering. Here, we present a method for generating a spin supercurrent by using only a single homogeneous magnetic element. Remarkably, the spin supercurrent generated in this way does not decay spatially, in stark contrast to normal spin currents that remain polarized only up to the spin relaxation length. We also expose the existence of a superconductivity-mediated torque even without magnetic inhomogeneities, showing that the different components of the spin supercurrent polarization respond fundamentally differently to a change in the superconducting phase difference. This establishes a mechanism for tuning dissipationless spin and charge flow separately, and confirms the advantage that superconductors can offer in spintronics. PMID:27045733

  8. Controlling superconducting spin flow with spin-flip immunity using a single homogeneous ferromagnet

    NASA Astrophysics Data System (ADS)

    Jacobsen, Sol H.; Kulagina, Iryna; Linder, Jacob

    2016-04-01

    Spin transport via electrons is typically plagued by Joule heating and short decay lengths due to spin-flip scattering. It is known that dissipationless spin currents can arise when using conventional superconducting contacts, yet this has only been experimentally demonstrated when using intricate magnetically inhomogeneous multilayers, or in extreme cases such as half-metals with interfacial magnetic disorder. Moreover, it is unknown how such spin supercurrents decay in the presence of spin-flip scattering. Here, we present a method for generating a spin supercurrent by using only a single homogeneous magnetic element. Remarkably, the spin supercurrent generated in this way does not decay spatially, in stark contrast to normal spin currents that remain polarized only up to the spin relaxation length. We also expose the existence of a superconductivity-mediated torque even without magnetic inhomogeneities, showing that the different components of the spin supercurrent polarization respond fundamentally differently to a change in the superconducting phase difference. This establishes a mechanism for tuning dissipationless spin and charge flow separately, and confirms the advantage that superconductors can offer in spintronics.

  9. Coherent control of a single ²⁹Si nuclear spin qubit.

    PubMed

    Pla, Jarryd J; Mohiyaddin, Fahd A; Tan, Kuan Y; Dehollain, Juan P; Rahman, Rajib; Klimeck, Gerhard; Jamieson, David N; Dzurak, Andrew S; Morello, Andrea

    2014-12-12

    Magnetic fluctuations caused by the nuclear spins of a host crystal are often the leading source of decoherence for many types of solid-state spin qubit. In group-IV semiconductor materials, the spin-bearing nuclei are sufficiently rare that it is possible to identify and control individual host nuclear spins. This Letter presents the first experimental detection and manipulation of a single ²⁹Si nuclear spin. The quantum nondemolition single-shot readout of the spin is demonstrated, and a Hahn echo measurement reveals a coherence time of T₂=6.3(7)  ms—in excellent agreement with bulk experiments. Atomistic modeling combined with extracted experimental parameters provides possible lattice sites for the ²⁹Si atom under investigation. These results demonstrate that single ²⁹Si nuclear spins could serve as a valuable resource in a silicon spin-based quantum computer.

  10. Active Morphology Control for Concomitant Long Distance Spin Transport and Photoresponse in a Single Organic Device.

    PubMed

    Sun, Xiangnan; Bedoya-Pinto, Amilcar; Mao, Zupan; Gobbi, Marco; Yan, Wenjing; Guo, Yunlong; Atxabal, Ainhoa; Llopis, Roger; Yu, Gui; Liu, Yunqi; Chuvilin, Andrey; Casanova, Felix; Hueso, Luis E

    2016-04-01

    Long distance spin transport and photoresponse are demonstrated in a single F16 CuPc spin valve. By introducing a low-temperature strategy for controlling the morphology of the organic layer during the fabrication of a molecular spin valve, a large spin-diffusion length up to 180 nm is achieved at room temperature. Magnetoresistive and photoresponsive signals are simultaneously observed even in an air atmosphere. PMID:26823157

  11. Single spin magnetic resonance

    NASA Astrophysics Data System (ADS)

    Wrachtrup, Jörg; Finkler, Amit

    2016-08-01

    Different approaches have improved the sensitivity of either electron or nuclear magnetic resonance to the single spin level. For optical detection it has essentially become routine to observe a single electron spin or nuclear spin. Typically, the systems in use are carefully designed to allow for single spin detection and manipulation, and of those systems, diamond spin defects rank very high, being so robust that they can be addressed, read out and coherently controlled even under ambient conditions and in a versatile set of nanostructures. This renders them as a new type of sensor, which has been shown to detect single electron and nuclear spins among other quantities like force, pressure and temperature. Adapting pulse sequences from classic NMR and EPR, and combined with high resolution optical microscopy, proximity to the target sample and nanoscale size, the diamond sensors have the potential to constitute a new class of magnetic resonance detectors with single spin sensitivity. As diamond sensors can be operated under ambient conditions, they offer potential application across a multitude of disciplines. Here we review the different existing techniques for magnetic resonance, with a focus on diamond defect spin sensors, showing their potential as versatile sensors for ultra-sensitive magnetic resonance with nanoscale spatial resolution.

  12. Single spin magnetic resonance.

    PubMed

    Wrachtrup, Jörg; Finkler, Amit

    2016-08-01

    Different approaches have improved the sensitivity of either electron or nuclear magnetic resonance to the single spin level. For optical detection it has essentially become routine to observe a single electron spin or nuclear spin. Typically, the systems in use are carefully designed to allow for single spin detection and manipulation, and of those systems, diamond spin defects rank very high, being so robust that they can be addressed, read out and coherently controlled even under ambient conditions and in a versatile set of nanostructures. This renders them as a new type of sensor, which has been shown to detect single electron and nuclear spins among other quantities like force, pressure and temperature. Adapting pulse sequences from classic NMR and EPR, and combined with high resolution optical microscopy, proximity to the target sample and nanoscale size, the diamond sensors have the potential to constitute a new class of magnetic resonance detectors with single spin sensitivity. As diamond sensors can be operated under ambient conditions, they offer potential application across a multitude of disciplines. Here we review the different existing techniques for magnetic resonance, with a focus on diamond defect spin sensors, showing their potential as versatile sensors for ultra-sensitive magnetic resonance with nanoscale spatial resolution.

  13. Coherent control of single spins in silicon carbide at room temperature.

    PubMed

    Widmann, Matthias; Lee, Sang-Yun; Rendler, Torsten; Son, Nguyen Tien; Fedder, Helmut; Paik, Seoyoung; Yang, Li-Ping; Zhao, Nan; Yang, Sen; Booker, Ian; Denisenko, Andrej; Jamali, Mohammad; Momenzadeh, S Ali; Gerhardt, Ilja; Ohshima, Takeshi; Gali, Adam; Janzén, Erik; Wrachtrup, Jörg

    2015-02-01

    Spins in solids are cornerstone elements of quantum spintronics. Leading contenders such as defects in diamond or individual phosphorus dopants in silicon have shown spectacular progress, but either lack established nanotechnology or an efficient spin/photon interface. Silicon carbide (SiC) combines the strength of both systems: it has a large bandgap with deep defects and benefits from mature fabrication techniques. Here, we report the characterization of photoluminescence and optical spin polarization from single silicon vacancies in SiC, and demonstrate that single spins can be addressed at room temperature. We show coherent control of a single defect spin and find long spin coherence times under ambient conditions. Our study provides evidence that SiC is a promising system for atomic-scale spintronics and quantum technology. PMID:25437256

  14. Single-spin CCD

    NASA Astrophysics Data System (ADS)

    Baart, T. A.; Shafiei, M.; Fujita, T.; Reichl, C.; Wegscheider, W.; Vandersypen, L. M. K.

    2016-04-01

    Spin-based electronics or spintronics relies on the ability to store, transport and manipulate electron spin polarization with great precision. In its ultimate limit, information is stored in the spin state of a single electron, at which point quantum information processing also becomes a possibility. Here, we demonstrate the manipulation, transport and readout of individual electron spins in a linear array of three semiconductor quantum dots. First, we demonstrate single-shot readout of three spins with fidelities of 97% on average, using an approach analogous to the operation of a charge-coupled device (CCD). Next, we perform site-selective control of the three spins, thereby writing the content of each pixel of this ‘single-spin charge-coupled device’. Finally, we show that shuttling an electron back and forth in the array hundreds of times, covering a cumulative distance of 80 μm, has negligible influence on its spin projection. Extrapolating these results to the case of much larger arrays points at a diverse range of potential applications, from quantum information to imaging and sensing.

  15. Addressable single-spin control in multiple quantum dots coupled in series

    NASA Astrophysics Data System (ADS)

    Nakajima, Takashi

    2015-03-01

    Electron spin in semiconductor quantum dots (QDs) is promising building block of quantum computers for its controllability and potential scalability. Recent experiments on GaAs QDs have demonstrated necessary ingredients of universal quantum gate operations: single-spin rotations by electron spin resonance (ESR) which is virtually free from the effect of nuclear spin fluctuation, and pulsed control of two-spin entanglement. The scalability of this architecture, however, has remained to be demonstrated in the real world. In this talk, we will present our recent results on implementing single-spin-based qubits in triple, quadruple, and quintuple QDs based on a series coupled architecture defined by gate electrodes. Deterministic initialization of individual spin states and spin-state readout were performed by the pulse operation of detuning between two neighboring QDs. The spin state was coherently manipulated by ESR, where each spin in different QDs is addressed by the shift of the resonance frequency due to the inhomogeneous magnetic field induced by the micro magnet deposited on top of the QDs. Control of two-spin entanglement was also demonstrated. We will discuss key issues for implementing quantum algorithms based on three or more qubits, including the effect of a nuclear spin bath, single-shot readout fidelity, and tuning of multiple qubit devices. Our approaches to these issues will be also presented. This research is supported by Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST) from JSPS, IARPA project ``Multi-Qubit Coherent Operations'' through Copenhagen University, and Grant-in-Aid for Scientific Research from JSPS.

  16. Coherent control of single spins in a silicon carbide pn junction device at room temperature

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Yun; Widmann, Matthias; Booker, Ian; Niethammer, Matthias; Ohshima, Takeshi; Gali, Adam; Son, Nguyen T.; Janzén, Erik; Wrachtrup, Joerg

    Spins in single defects have been studied for quantum information science and quantum metrology. It has been proven that spins of the single nitrogen-vacancy (NV) centers in diamond can be used as a quantum bit, and a single spin sensor operating at ambient conditions. Recently, there has been a growing interest in a new material in which color centers similar to NV centers can be created and whose electrical properties can also be well controlled, thus existing electronic devices can easily be adapted as a platform for quantum applications. We recently reported that single spins of negatively charged silicon vacancies in SiC can be coherently controlled and long-lived at room temperature. As a next step, we isolated single silicon vacancies in a SiC pn junction device and investigated how the change in Fermi level, induced by applying bias, alters the charge state of silicon vacancies, thus affects the spin state control. This study will allow us to envision quantum applications based on single defects incorporated in modern electronic devices.

  17. Controlled Rephasing of Single Collective Spin Excitations in a Cold Atomic Quantum Memory.

    PubMed

    Albrecht, Boris; Farrera, Pau; Heinze, Georg; Cristiani, Matteo; de Riedmatten, Hugues

    2015-10-16

    We demonstrate active control of inhomogeneous dephasing and rephasing for single collective atomic spin excitations (spin waves) created by spontaneous Raman scattering in a quantum memory based on cold 87Rb atoms. The control is provided by a reversible external magnetic field gradient inducing an inhomogeneous broadening of the atomic hyperfine levels. We demonstrate experimentally that active rephasing preserves the single photon nature of the retrieved photons. Finally, we show that the control of the inhomogeneous dephasing enables the creation of time-separated spin waves in a single ensemble followed by a selective read-out in time. This is an important step towards the implementation of a functional temporally multiplexed quantum repeater node.

  18. All-electrical control of a singlet-triplet qubit coupled to a single nuclear spin

    NASA Astrophysics Data System (ADS)

    Jacobson, N. Tobias; Harvey-Collard, Patrick; Baczewski, Andrew; Gamble, John; Rudolph, Martin; Nielsen, Erik; Muller, Richard; Carroll, Malcolm

    Donor nuclear spins in isotopically purified silicon have very long coherence times, suggesting that they may form high-quality quantum memories. We propose that coupling these nuclear spins to few-electron quantum dots could enable nuclear spin readout and two-qubit operations of the joint quantum dot and nuclear spin system without the need for electron spin resonance. As a step towards this goal, our group recently demonstrated coherent singlet/triplet electron spin rotations induced by the hyperfine interaction between electronic spin degrees of freedom and a single nuclear spin in isotopically purified silicon. In this talk, I will discuss the feasibility of universal all-electrical control of such a singlet/triplet electron spin qubit and explore the decoherence mechanisms that we expect to dominate. Finally, I will examine the relative merits of AC and pulsed DC gating schemes. Sandia is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy National Nuclear Security Administration under Contract No. DE-AC04- 94AL85000.

  19. Voltage control of electron-nuclear spin correlation time in a single quantum dot

    NASA Astrophysics Data System (ADS)

    Nilsson, J.; Bouet, L.; Bennett, A. J.; Amand, T.; Stevenson, R. M.; Farrer, I.; Ritchie, D. A.; Kunz, S.; Marie, X.; Shields, A. J.; Urbaszek, B.

    2013-08-01

    We demonstrate bias control of the efficiency of the hyperfine coupling between a single electron in an InAs quantum dot and the surrounding nuclear spins monitored through the positively charged exciton X+ emission. In applied longitudinal magnetic fields, we vary simultaneously the correlation time of the hyperfine interaction and the nuclear spin relaxation time and thereby the amplitude of the achieved dynamic nuclear polarization under optical pumping conditions. In applied transverse magnetic fields, a change in the applied bias allows a switch from the anomalous Hanle effect to the standard electron spin depolarization curves.

  20. Controlled rephasing of single spin-waves in a quantum memory based on cold atoms

    NASA Astrophysics Data System (ADS)

    Farrera, Pau; Albrecht, Boris; Heinze, Georg; Cristiani, Matteo; de Riedmatten, Hugues; Quantum Photonics With Solids; Atoms Team

    2015-05-01

    Quantum memories for light allow a reversible transfer of quantum information between photons and long lived matter quantum bits. In atomic ensembles, this information is commonly stored in the form of single collective spin excitations (spin-waves). In this work we demonstrate that we can actively control the dephasing of the spin-waves created in a quantum memory based on a cold Rb87 atomic ensemble. The control is provided by an external magnetic field gradient, which induces an inhomogeneous broadening of the atomic hyperfine levels. We show that acting on this gradient allows to control the dephasing of individual spin-waves and to induce later a rephasing. The spin-waves are then mapped into single photons, and we demonstrate experimentally that the active rephasing preserves the sub-Poissonian statistics of the retrieved photons. Finally we show that this rephasing control enables the creation and storage of multiple spin-waves in different temporal modes, which can be selectively readout. This is an important step towards the implementation of a functional temporally multiplexed quantum memory for quantum repeaters. We acknowledge support from the ERC starting grant, the Spanish Ministry of Economy and Competitiveness, the Fondo Europeo de Desarrollo Regional, and the International PhD- fellowship program ``la Caixa''-Severo Ochoa @ICFO.

  1. Measurement and control of single spins in diamond above 600 K

    NASA Astrophysics Data System (ADS)

    Toyli, David M.

    2013-03-01

    The nitrogen vacancy (NV) center in diamond stands out among spin qubit systems in large part because its spin can be controlled under ambient conditions whereas most other solid state qubits operate only at cryogenic temperatures. However, despite the intense interest in the NV center's room temperature properties for nanoscale sensing and quantum information applications, the ultimate thermal limits to its measurement and control have been largely unknown. We demonstrate that the NV center's spin can be optically addressed and coherently controlled at temperatures exceeding 600 K and show that its addressability is eventually limited by thermal quenching of the optical spin readout. These measurements, in combination with computational studies, provide important information about the electronic states that facilitate the optical spin measurement and, moreover, suggest that the coherence of the NV center's spin states could be utilized for thermometry. We infer that single spins in diamond offer temperature sensitivities better than 100 mK/√{ Hz} up to 600 K using conventional sensing techniques and show that advanced measurement schemes provide a pathway to reach 10 mK/√{ Hz} sensitivities. Together with diamond's ideal thermal and mechanical properties, these results suggest that NV center thermometers could be applied in cellular thermometry and scanning thermal microscopy. This work was funded by AFOSR, ARO, and DARPA.

  2. Controlled Complete Suppression of Single-Atom Inelastic Spin and Orbital Cotunneling.

    PubMed

    Bryant, Benjamin; Toskovic, Ranko; Ferrón, Alejandro; Lado, José L; Spinelli, Anna; Fernández-Rossier, Joaquín; Otte, Alexander F

    2015-10-14

    The inelastic portion of the tunnel current through an individual magnetic atom grants unique access to read out and change the atom's spin state, but it also provides a path for spontaneous relaxation and decoherence. Controlled closure of the inelastic channel would allow for the latter to be switched off at will, paving the way to coherent spin manipulation in single atoms. Here, we demonstrate complete closure of the inelastic channels for both spin and orbital transitions due to a controlled geometric modification of the atom's environment, using scanning tunneling microscopy (STM). The observed suppression of the excitation signal, which occurs for Co atoms assembled into chains on a Cu2N substrate, indicates a structural transition affecting the dz(2) orbital, effectively cutting off the STM tip from the spin-flip cotunneling path.

  3. Controlled Complete Suppression of Single-Atom Inelastic Spin and Orbital Cotunneling.

    PubMed

    Bryant, Benjamin; Toskovic, Ranko; Ferrón, Alejandro; Lado, José L; Spinelli, Anna; Fernández-Rossier, Joaquín; Otte, Alexander F

    2015-10-14

    The inelastic portion of the tunnel current through an individual magnetic atom grants unique access to read out and change the atom's spin state, but it also provides a path for spontaneous relaxation and decoherence. Controlled closure of the inelastic channel would allow for the latter to be switched off at will, paving the way to coherent spin manipulation in single atoms. Here, we demonstrate complete closure of the inelastic channels for both spin and orbital transitions due to a controlled geometric modification of the atom's environment, using scanning tunneling microscopy (STM). The observed suppression of the excitation signal, which occurs for Co atoms assembled into chains on a Cu2N substrate, indicates a structural transition affecting the dz(2) orbital, effectively cutting off the STM tip from the spin-flip cotunneling path. PMID:26366713

  4. Electrically controlling single-spin qubits in a continuous microwave field

    PubMed Central

    Laucht, Arne; Muhonen, Juha T.; Mohiyaddin, Fahd A.; Kalra, Rachpon; Dehollain, Juan P.; Freer, Solomon; Hudson, Fay E.; Veldhorst, Menno; Rahman, Rajib; Klimeck, Gerhard; Itoh, Kohei M.; Jamieson, David N.; McCallum, Jeffrey C.; Dzurak, Andrew S.; Morello, Andrea

    2015-01-01

    Large-scale quantum computers must be built upon quantum bits that are both highly coherent and locally controllable. We demonstrate the quantum control of the electron and the nuclear spin of a single 31P atom in silicon, using a continuous microwave magnetic field together with nanoscale electrostatic gates. The qubits are tuned into resonance with the microwave field by a local change in electric field, which induces a Stark shift of the qubit energies. This method, known as A-gate control, preserves the excellent coherence times and gate fidelities of isolated spins, and can be extended to arbitrarily many qubits without requiring multiple microwave sources. PMID:26601166

  5. Electrically controlling single-spin qubits in a continuous microwave field.

    PubMed

    Laucht, Arne; Muhonen, Juha T; Mohiyaddin, Fahd A; Kalra, Rachpon; Dehollain, Juan P; Freer, Solomon; Hudson, Fay E; Veldhorst, Menno; Rahman, Rajib; Klimeck, Gerhard; Itoh, Kohei M; Jamieson, David N; McCallum, Jeffrey C; Dzurak, Andrew S; Morello, Andrea

    2015-04-01

    Large-scale quantum computers must be built upon quantum bits that are both highly coherent and locally controllable. We demonstrate the quantum control of the electron and the nuclear spin of a single (31)P atom in silicon, using a continuous microwave magnetic field together with nanoscale electrostatic gates. The qubits are tuned into resonance with the microwave field by a local change in electric field, which induces a Stark shift of the qubit energies. This method, known as A-gate control, preserves the excellent coherence times and gate fidelities of isolated spins, and can be extended to arbitrarily many qubits without requiring multiple microwave sources. PMID:26601166

  6. Controlling electronic access to the spin excitations of a single molecule in a tunnel junction

    NASA Astrophysics Data System (ADS)

    Hirjibehedin, Cyrus F.; Warner, Ben; El Hallak, Fadi; Prueser, Henning; Ajibade, Afolabi; Gill, Tobias G.; Fisher, Andrew J.; Persson, Mats

    Spintronic phenomena can be utilized to create new devices with applications in data storage and sensing. Scaling these down to the single molecule level requires controlling the properties of the current-carrying orbitals to enable access to spin states through phenomena such as inelastic electron tunneling. Here we show that the spintronic properties of a tunnel junction containing a single molecule can be controlled by their coupling to the local environment. For tunneling through iron phthalocyanine (FePc) on an insulating copper nitride (Cu2N) monolayer above Cu(001), we find that spin transitions may be strongly excited depending on the binding site of the central Fe atom. Different interactions between the Fe and the underlying Cu or N atoms shift the Fe d-orbitals with respect to the Fermi energy, and control the relative strength of the spin excitations, an effect that can described in a simple co-tunneling model. This work demonstrates the importance of the atomic-scale environment in the development of single molecule spintronic devices.

  7. Doping controlled spin reorientation in dysprosium-samarium orthoferrite single crystals

    NASA Astrophysics Data System (ADS)

    Cao, Shixun; Zhao, Weiyao; Kang, Baojuan; Zhang, Jincang; Ren, Wei

    2015-03-01

    As one of the most important phase transitions, spin reorientation (SR) in rare earth transition metal oxides draws much attention of emerging materials technologies. The origin of SR is the competition between different spin configurations which possess different free energy. We report the control of spin reorientation (SR) transition in perovskite rare earth orthoferrite Dy1-xSmxFeO3, a whole family of single crystals grown by optical floating zone method from x =0 to 1. Temperature dependence of the magnetizations under zero-field-cooling (ZFC) and field-cooling (FC) processes are studied. We have found a remarkable linear change of SR transition temperature in Sm-rich samples for x>0.2, which covers an extremely wide temperature range including room temperature. The a-axis magnetization curves under FCC process bifurcate from and then jump down to that of warming process (ZFC and FCW curves) in single crystals when x =0.5-0.9, suggesting complicated 4f-3d electron interactions among Dy3+-Sm3+, Dy3+-Fe3+, and Sm3+-Fe3+ sublattices of diverse magnetic configurations for materials physics and design. The magnetic properties and the doping effect on SR transition temperature in these single crystals might be useful in the spintronics device application. This work is supported by the National Key Basic Research Program of China (Grant No. 2015CB921600), and the National Natural Science Foundation of China (NSFC, Nos. 51372149, 50932003, 11274222).

  8. Analysis of state-of-the-art single-thruster attitude control techniques for spinning penetrator

    NASA Astrophysics Data System (ADS)

    Raus, Robin; Gao, Yang; Wu, Yunhua; Watt, Mark

    2012-07-01

    The attitude dynamics and manoeuvre survey in this paper is performed for a mission scenario involving a penetrator-type spacecraft: an axisymmetric prolate spacecraft spinning around its minor axis of inertia performing a 90° spin axis reorientation manoeuvre. In contrast to most existing spacecraft only one attitude control thruster is available, providing a control torque perpendicular to the spin axis. Having only one attitude thruster on a spinning spacecraft could be preferred for spacecraft simplicity (lower mass, lower power consumption etc.), or it could be imposed in the context of redundancy/contingency operations. This constraint does yield restrictions on the thruster timings, depending on the ratio of minor to major moments of inertia among other parameters. The Japanese Lunar-A penetrator spacecraft proposal is a good example of such a single-thruster spin-stabilised prolate spacecraft. The attitude dynamics of a spinning rigid body are first investigated analytically, then expanded for the specific case of a prolate and axisymmetric rigid body and finally a cursory exploration of non-rigid body dynamics is made. Next two well-known techniques for manoeuvring a spin-stabilised spacecraft, the Half-cone/Multiple Half-cone and the Rhumb line slew, are compared with two new techniques, the Sector-Arc Slew developed by Astrium Satellites and the Dual-cone developed at Surrey Space Centre. Each technique is introduced and characterised by means of simulation results and illustrations based on the penetrator mission scenario and a brief robustness analysis is performed against errors in moments of inertia and spin rate. Also, the relative benefits of each slew algorithm are discussed in terms of slew accuracy, energy (propellant) efficiency and time efficiency. For example, a sequence of half-cone manoeuvres (a Multi-half-cone manoeuvre) tends to be more energy-efficient than one half-cone for the same final slew angle, but more time-consuming. As another

  9. Control of coherence among the spins of a single electron and the three nearest neighbor {sup 13}C nuclei of a nitrogen-vacancy center in diamond

    SciTech Connect

    Shimo-Oka, T.; Miwa, S.; Suzuki, Y.; Mizuochi, N.; Kato, H.; Yamasaki, S.; Jelezko, F.

    2015-04-13

    Individual nuclear spins in diamond can be optically detected through hyperfine couplings with the electron spin of a single nitrogen-vacancy (NV) center; such nuclear spins have outstandingly long coherence times. Among the hyperfine couplings in the NV center, the nearest neighbor {sup 13}C nuclear spins have the largest coupling strength. Nearest neighbor {sup 13}C nuclear spins have the potential to perform fastest gate operations, providing highest fidelity in quantum computing. Herein, we report on the control of coherences in the NV center where all three nearest neighbor carbons are of the {sup 13}C isotope. Coherence among the three and four qubits are generated and analyzed at room temperature.

  10. Magnetoelectric control of spin currents

    NASA Astrophysics Data System (ADS)

    Gómez, J. E.; Vargas, J. M.; Avilés-Félix, L.; Butera, A.

    2016-06-01

    The ability to control the spin current injection has been explored on a hybrid magnetoelectric system consisting of a (011)-cut ferroelectric lead magnesium niobate-lead titanate (PMNT) single crystal, a ferromagnetic FePt alloy, and a metallic Pt. With this PMNT/FePt/Pt structure we have been able to control the magnetic field position or the microwave excitation frequency at which the spin pumping phenomenon between FePt and Pt occurs. We demonstrate that the magnetoelectric heterostructure operating in the L-T (longitudinal magnetized-transverse polarized) mode couples the PMNT crystal to the magnetostrictive FePt/Pt bilayer, displaying a strong magnetoelectric coefficient of ˜140 Oe cm kV-1. Our results show that this mechanism can be effectively exploited as a tunable spin current intensity emitter and open the possibility to create an oscillating or a bistable switch to effectively manipulate spin currents.

  11. Manipulation of single nanodiamonds to ultrathin fiber-taper nanofibers and control of NV-spin states toward fiber-integrated λ-systems

    NASA Astrophysics Data System (ADS)

    Fujiwara, Masazumi; Yoshida, Kazuma; Noda, Tetsuya; Takashima, Hideaki; Schell, Andreas W.; Mizuochi, Norikazu; Takeuchi, Shigeki

    2016-11-01

    We report on the coupling of single nitrogen vacancy (NV) centers to ultrathin fiber-taper nanofibers by the manipulation of single diamond nanocrystals on the nanofibers under real-time observation of nanodiamond fluorescence. Spin-dependent fluorescence of the single NV centers is efficiently detected through the nanofiber. We show control of the spin sub-level structure of the electronic ground state using an external magnetic field and clearly observe a frequency fine tuning of {m}{{S}}=| +/- 1> . This observation demonstrates a possibility of realizing fiber-integrated quantum λ-systems, which can be used for various quantum information devices including push–pull quantum memory and quantum gates.

  12. Electrical control of quantum dot spin qubits

    NASA Astrophysics Data System (ADS)

    Laird, Edward Alexander

    This thesis presents experiments exploring the interactions of electron spins with electric fields in devices of up to four quantum dots. These experiments are particularly motivated by the prospect of using electric fields to control spin qubits. A novel hyperfine effect on a single spin in a quantum dot is presented in Chapter 2. Fluctuations of the nuclear polarization allow single-spin resonance to be driven by an oscillating electric field. Spin resonance spectroscopy revealed a nuclear polarization built up inside the quantum dot device by driving the resonance. The evolution of two coupled spins is controlled by the combination of hyperfine interaction, which tends to cause spin dephasing, and exchange, which tends to prevent it. In Chapter 3, dephasing is studied in a device with tunable exchange, probing the crossover between exchange-dominated and hyperfine-dominated regimes. In agreement with theoretical predictions, oscillations of the spin conversion probability and saturation of dephasing are observed. Chapter 4 deals with a three-dot device, suggested as a potential qubit controlled entirely by exchange. Preparation and readout of the qubit state are demonstrated, together with one out of two coherent exchange operations needed for arbitrary manipulations. A new readout technique allowing rapid device measurement is described. In Chapter 5, an attempt to make a two-qubit gate using a four-dot device is presented. Although spin qubit operation has not yet been possible, the electrostatic interaction between pairs of dots was measured to be sufficient in principle for coherent qubit coupling.

  13. Single-parameter spin-pumping in driven metallic rings with spin-orbit coupling

    SciTech Connect

    Ramos, J. P.; Apel, V. M.; Foa Torres, L. E. F.; Orellana, P. A.

    2014-03-28

    We consider the generation of a pure spin-current at zero bias voltage with a single time-dependent potential. To such end we study a device made of a mesoscopic ring connected to electrodes and clarify the interplay between a magnetic flux, spin-orbit coupling, and non-adiabatic driving in the production of a spin and electrical current. By using Floquet theory, we show that the generated spin to charge current ratio can be controlled by tuning the spin-orbit coupling.

  14. Detection and Control of Individual Nuclear Spins Using a Weakly Coupled Electron Spin

    SciTech Connect

    Taminiau, T.H.; Wagenaar, J.J.T.; van der Sar, T.; Jelezko, F.; Dobrovitski, Viatcheslav V.; Hanson, R.

    2012-09-28

    We experimentally isolate, characterize, and coherently control up to six individual nuclear spins that are weakly coupled to an electron spin in diamond. Our method employs multipulse sequences on the electron spin that resonantly amplify the interaction with a selected nuclear spin and at the same time dynamically suppress decoherence caused by the rest of the spin bath. We are able to address nuclear spins with interaction strengths that are an order of magnitude smaller than the electron spin dephasing rate. Our results provide a route towards tomography with single-nuclear-spin sensitivity and greatly extend the number of available quantum bits for quantum information processing in diamond.

  15. Single-electron Spin Resonance in a Quadruple Quantum Dot

    PubMed Central

    Otsuka, Tomohiro; Nakajima, Takashi; Delbecq, Matthieu R.; Amaha, Shinichi; Yoneda, Jun; Takeda, Kenta; Allison, Giles; Ito, Takumi; Sugawara, Retsu; Noiri, Akito; Ludwig, Arne; Wieck, Andreas D.; Tarucha, Seigo

    2016-01-01

    Electron spins in semiconductor quantum dots are good candidates of quantum bits for quantum information processing. Basic operations of the qubit have been realized in recent years: initialization, manipulation of single spins, two qubit entanglement operations, and readout. Now it becomes crucial to demonstrate scalability of this architecture by conducting spin operations on a scaled up system. Here, we demonstrate single-electron spin resonance in a quadruple quantum dot. A few-electron quadruple quantum dot is formed within a magnetic field gradient created by a micro-magnet. We oscillate the wave functions of the electrons in the quantum dots by applying microwave voltages and this induces electron spin resonance. The resonance energies of the four quantum dots are slightly different because of the stray field created by the micro-magnet and therefore frequency-resolved addressable control of each electron spin resonance is possible. PMID:27550534

  16. Single-electron Spin Resonance in a Quadruple Quantum Dot.

    PubMed

    Otsuka, Tomohiro; Nakajima, Takashi; Delbecq, Matthieu R; Amaha, Shinichi; Yoneda, Jun; Takeda, Kenta; Allison, Giles; Ito, Takumi; Sugawara, Retsu; Noiri, Akito; Ludwig, Arne; Wieck, Andreas D; Tarucha, Seigo

    2016-01-01

    Electron spins in semiconductor quantum dots are good candidates of quantum bits for quantum information processing. Basic operations of the qubit have been realized in recent years: initialization, manipulation of single spins, two qubit entanglement operations, and readout. Now it becomes crucial to demonstrate scalability of this architecture by conducting spin operations on a scaled up system. Here, we demonstrate single-electron spin resonance in a quadruple quantum dot. A few-electron quadruple quantum dot is formed within a magnetic field gradient created by a micro-magnet. We oscillate the wave functions of the electrons in the quantum dots by applying microwave voltages and this induces electron spin resonance. The resonance energies of the four quantum dots are slightly different because of the stray field created by the micro-magnet and therefore frequency-resolved addressable control of each electron spin resonance is possible. PMID:27550534

  17. Single-electron Spin Resonance in a Quadruple Quantum Dot.

    PubMed

    Otsuka, Tomohiro; Nakajima, Takashi; Delbecq, Matthieu R; Amaha, Shinichi; Yoneda, Jun; Takeda, Kenta; Allison, Giles; Ito, Takumi; Sugawara, Retsu; Noiri, Akito; Ludwig, Arne; Wieck, Andreas D; Tarucha, Seigo

    2016-08-23

    Electron spins in semiconductor quantum dots are good candidates of quantum bits for quantum information processing. Basic operations of the qubit have been realized in recent years: initialization, manipulation of single spins, two qubit entanglement operations, and readout. Now it becomes crucial to demonstrate scalability of this architecture by conducting spin operations on a scaled up system. Here, we demonstrate single-electron spin resonance in a quadruple quantum dot. A few-electron quadruple quantum dot is formed within a magnetic field gradient created by a micro-magnet. We oscillate the wave functions of the electrons in the quantum dots by applying microwave voltages and this induces electron spin resonance. The resonance energies of the four quantum dots are slightly different because of the stray field created by the micro-magnet and therefore frequency-resolved addressable control of each electron spin resonance is possible.

  18. Single-electron Spin Resonance in a Quadruple Quantum Dot

    NASA Astrophysics Data System (ADS)

    Otsuka, Tomohiro; Nakajima, Takashi; Delbecq, Matthieu R.; Amaha, Shinichi; Yoneda, Jun; Takeda, Kenta; Allison, Giles; Ito, Takumi; Sugawara, Retsu; Noiri, Akito; Ludwig, Arne; Wieck, Andreas D.; Tarucha, Seigo

    2016-08-01

    Electron spins in semiconductor quantum dots are good candidates of quantum bits for quantum information processing. Basic operations of the qubit have been realized in recent years: initialization, manipulation of single spins, two qubit entanglement operations, and readout. Now it becomes crucial to demonstrate scalability of this architecture by conducting spin operations on a scaled up system. Here, we demonstrate single-electron spin resonance in a quadruple quantum dot. A few-electron quadruple quantum dot is formed within a magnetic field gradient created by a micro-magnet. We oscillate the wave functions of the electrons in the quantum dots by applying microwave voltages and this induces electron spin resonance. The resonance energies of the four quantum dots are slightly different because of the stray field created by the micro-magnet and therefore frequency-resolved addressable control of each electron spin resonance is possible.

  19. Single-Spin Asymmetries at CLAS

    SciTech Connect

    Avakian, Harutyun

    2003-05-01

    Single spin asymmetries (SSA) are crucial tools in the study of the spin structure of hadrons in pion electroproduction, since they are directly related to some hot topics,including transverse polarization distribution functions, fragmentation of polarized quarks and generalized parton distribution functions. At low beam energies, when the virtual photon has a relatively large angle with respect to the initial spin direction, the measured single-target spin-dependent sin φ moment in the cross section for the longitudinally polarized target contain contributions from the target spin components, both longitudinal and transverse with respect to the photon direction.This contribution presents preliminary results from Jefferson Lab's CLAS detector on beam and target SSA in pion azimuthal distributions in one particle inclusive electroproduction in the DIS regime (Q2 > 1GeV 2,W > 2GeV ) off a polarized NH3 target.

  20. Resolution of Single Spin Flips of a Single Proton

    NASA Astrophysics Data System (ADS)

    Mooser, A.; Kracke, H.; Blaum, K.; Bräuninger, S. A.; Franke, K.; Leiteritz, C.; Quint, W.; Rodegheri, C. C.; Ulmer, S.; Walz, J.

    2013-04-01

    The spin magnetic moment of a single proton in a cryogenic Penning trap was coupled to the particle’s axial motion with a superimposed magnetic bottle. Jumps in the oscillation frequency indicate spin flips and were identified using a Bayesian analysis.

  1. Single spin asymmetries in electroproduction at CLAS

    SciTech Connect

    Harut Avakian; Latifa Elouadrhiri

    2004-06-02

    We present measurements of spin asymmetries in semi-inclusive processes in hard scattering kinematics using a 5.7 GeV electron beam and the CEBAF Large Acceptance Spectrometer (CLAS) at JLab. Scattering of longitudinally polarized electrons of an unpolarized liquid-hydrogen and off a polarized NH{sub 3} targets was studied over a wide range of kinematics. Non-zero single-beam and single-target spin asymmetries have been observed in semi-inclusive pion production in hard-scattering kinematics (Q{sup 2} > 1.2 GeV{sup 2}, W{sup 4} > 4 GeV{sup 2}). Systematic studies of factorization of x and z dependences have been done for different spin-dependent and spin-independent observables. No significant x/z dependence has been observed within statistical uncertainties, which is consistent with factorization of hard scattering and fragmentation processes.

  2. Nanoscale imaging of paramagnetic spin labels using a single spin in diamond

    NASA Astrophysics Data System (ADS)

    Ariyaratne, Amila; Myers, Bryan; Pelliccione, Matthew; Jayich, Ania

    Spin-labeling molecules with paramagnetic species is a powerful technique for probing molecular structure. However, current techniques are ensemble measurements, inherently lacking the sensitivity to detect a single spin or the conformational properties of a single biomolecule. In this talk, we demonstrate an imaging technique that has the promise of single-spin imaging and ultimately molecular structure imaging. We present two-dimensional nanoscale imaging of a monolayer of gadolinium (Gd) atomic spin labels at ambient conditions. The sensing element is a single nitrogen-vacancy (NV) center in diamond. A patterned monolayer of Gd atoms self-assembled on a Si atomic force microscopy tip is controllably interacted with and detected by the NV center. The fluctuating magnetic field generated by GHz-scale Gd spin flips relaxes the NV center in a manner that depends strongly on the Gd-NV separation. Using this technique, we demonstrate a Gd-induced reduction of the T1 relaxation time of the NV center with nm spatial resolution. Our results indicate that nanometer-scale imaging of individual electronic spins at ambient conditions is within reach. This will ultimately enable the study of structural and functional studies of single biomolecules in their native, folded state.

  3. A single-atom electron spin qubit in silicon.

    PubMed

    Pla, Jarryd J; Tan, Kuan Y; Dehollain, Juan P; Lim, Wee H; Morton, John J L; Jamieson, David N; Dzurak, Andrew S; Morello, Andrea

    2012-09-27

    A single atom is the prototypical quantum system, and a natural candidate for a quantum bit, or qubit--the elementary unit of a quantum computer. Atoms have been successfully used to store and process quantum information in electromagnetic traps, as well as in diamond through the use of the nitrogen-vacancy-centre point defect. Solid-state electrical devices possess great potential to scale up such demonstrations from few-qubit control to larger-scale quantum processors. Coherent control of spin qubits has been achieved in lithographically defined double quantum dots in both GaAs (refs 3-5) and Si (ref. 6). However, it is a formidable challenge to combine the electrical measurement capabilities of engineered nanostructures with the benefits inherent in atomic spin qubits. Here we demonstrate the coherent manipulation of an individual electron spin qubit bound to a phosphorus donor atom in natural silicon, measured electrically via single-shot read-out. We use electron spin resonance to drive Rabi oscillations, and a Hahn echo pulse sequence reveals a spin coherence time exceeding 200 µs. This time should be even longer in isotopically enriched (28)Si samples. Combined with a device architecture that is compatible with modern integrated circuit technology, the electron spin of a single phosphorus atom in silicon should be an excellent platform on which to build a scalable quantum computer. PMID:22992519

  4. Controlling spin relaxation with a cavity.

    PubMed

    Bienfait, A; Pla, J J; Kubo, Y; Zhou, X; Stern, M; Lo, C C; Weis, C D; Schenkel, T; Vion, D; Esteve, D; Morton, J J L; Bertet, P

    2016-03-01

    Spontaneous emission of radiation is one of the fundamental mechanisms by which an excited quantum system returns to equilibrium. For spins, however, spontaneous emission is generally negligible compared to other non-radiative relaxation processes because of the weak coupling between the magnetic dipole and the electromagnetic field. In 1946, Purcell realized that the rate of spontaneous emission can be greatly enhanced by placing the quantum system in a resonant cavity. This effect has since been used extensively to control the lifetime of atoms and semiconducting heterostructures coupled to microwave or optical cavities, and is essential for the realization of high-efficiency single-photon sources. Here we report the application of this idea to spins in solids. By coupling donor spins in silicon to a superconducting microwave cavity with a high quality factor and a small mode volume, we reach the regime in which spontaneous emission constitutes the dominant mechanism of spin relaxation. The relaxation rate is increased by three orders of magnitude as the spins are tuned to the cavity resonance, demonstrating that energy relaxation can be controlled on demand. Our results provide a general way to initialize spin systems into their ground state and therefore have applications in magnetic resonance and quantum information processing. They also demonstrate that the coupling between the magnetic dipole of a spin and the electromagnetic field can be enhanced up to the point at which quantum fluctuations have a marked effect on the spin dynamics; as such, they represent an important step towards the coherent magnetic coupling of individual spins to microwave photons. PMID:26878235

  5. Nonlinear Single Spin Spectrum Analyzer

    NASA Astrophysics Data System (ADS)

    Kotler, Shlomi; Akerman, Nitzan; Glickman, Yinnon; Ozeri, Roee

    2014-03-01

    Qubits have been used as linear spectrum analyzers of their environments, through the use of decoherence spectroscopy. Here we solve the problem of nonlinear spectral analysis, required for discrete noise induced by a strongly coupled environment. Our nonperturbative analytical model shows a nonlinear signal dependence on noise power, resulting in a spectral resolution beyond the Fourier limit as well as frequency mixing. We develop a noise characterization scheme adapted to this nonlinearity. We then apply it using a single trapped ion as a sensitive probe of strong, non-Gaussian, discrete magnetic field noise. Finally, we experimentally compared the performance of equidistant vs Uhrig modulation schemes for spectral analysis. Phys. Rev. Lett. 110, 110503 (2013). Synopsis at http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.110.110503 Current position: NIST, Boulder, CO.

  6. Nonlinear Single Spin Spectrum Analayzer

    NASA Astrophysics Data System (ADS)

    Kotler, Shlomi; Akerman, Nitzan; Glickman, Yinnon; Ozeri, Roee

    2014-05-01

    Qubits are excellent probes of their environment. When operating in the linear regime, they can be used as linear spectrum analyzers of the noise processes surrounding them. These methods fail for strong non-Gaussian noise where the qubit response is no longer linear. Here we solve the problem of nonlinear spectral analysis, required for strongly coupled environments. Our non-perturbative analytic model shows a nonlinear signal dependence on noise power, resulting in a spectral resolution beyond the Fourier limit as well as frequency mixing. We developed a noise characterization scheme adapted to this non-linearity. We then applied it using a single trapped 88Sr+ ion as the a sensitive probe of strong, non-Gaussian, discrete magnetic field noise. With this method, we attained a ten fold improvement over the standard Fourier limit. Finally, we experimentally compared the performance of equidistant vs. Uhrig modulation schemes for spectral analysis. Phys. Rev. Lett. 110, 110503 (2013), Synopsis at http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.110.110503 Current position: National Institute of Standards and Tehcnology, Boulder, CO.

  7. Quantum control of proximal spins using nanoscale magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Grinolds, M. S.; Maletinsky, P.; Hong, S.; Lukin, M. D.; Walsworth, R. L.; Yacoby, A.

    2011-09-01

    Quantum control of individual spins in condensed-matter systems is an emerging field with wide-ranging applications in spintronics, quantum computation and sensitive magnetometry. Recent experiments have demonstrated the ability to address and manipulate single electron spins through either optical or electrical techniques. However, it is a challenge to extend individual-spin control to nanometre-scale multi-electron systems, as individual spins are often irresolvable with existing methods. Here we demonstrate that coherent individual-spin control can be achieved with few- nanometre resolution for proximal electron spins by carrying out single-spin magnetic resonance imaging (MRI), which is realized using a scanning-magnetic-field gradient that is both strong enough to achieve nanometre spatial resolution and sufficiently stable for coherent spin manipulations. We apply this scanning-field-gradient MRI technique to electronic spins in nitrogen-vacancy (NV) centres in diamond and achieve nanometre resolution in imaging, characterization and manipulation of individual spins. For NV centres, our results in individual-spin control demonstrate an improvement of nearly two orders of magnitude in spatial resolution when compared with conventional optical diffraction-limited techniques. This scanning-field-gradient microscope enables a wide range of applications including materials characterization, spin entanglement and nanoscale magnetometry.

  8. Single-spin stochastic optical reconstruction microscopy

    PubMed Central

    Pfender, Matthias; Aslam, Nabeel; Waldherr, Gerald; Neumann, Philipp; Wrachtrup, Jörg

    2014-01-01

    We experimentally demonstrate precision addressing of single-quantum emitters by combined optical microscopy and spin resonance techniques. To this end, we use nitrogen vacancy (NV) color centers in diamond confined within a few ten nanometers as individually resolvable quantum systems. By developing a stochastic optical reconstruction microscopy (STORM) technique for NV centers, we are able to simultaneously perform sub–diffraction-limit imaging and optically detected spin resonance (ODMR) measurements on NV spins. This allows the assignment of spin resonance spectra to individual NV center locations with nanometer-scale resolution and thus further improves spatial discrimination. For example, we resolved formerly indistinguishable emitters by their spectra. Furthermore, ODMR spectra contain metrology information allowing for sub–diffraction-limit sensing of, for instance, magnetic or electric fields with inherently parallel data acquisition. As an example, we have detected nuclear spins with nanometer-scale precision. Finally, we give prospects of how this technique can evolve into a fully parallel quantum sensor for nanometer resolution imaging of delocalized quantum correlations. PMID:25267655

  9. Collins Mechanism Contributions to Single Spin Asymmetry

    SciTech Connect

    Yuan,F.

    2009-05-26

    We present recent developments on the single transverse spin physics, in particular, the Collins mechanism contributions in various hadronic reactions, such as semi-inclusive hadron production in DIS process, azimuthal distribution of hadron in high energy jet in pp collisions. We will demonstrate that the transverse momentum dependent and collinear factorization approaches are consistent with each other in the description of the Collins effects in the semi-inclusive hadron production in DIS process.

  10. Collins Mechanism Contributions to Single Spin Asymmetry

    SciTech Connect

    Yuan,F.

    2009-05-25

    We present recent developments on the single transverse spin physics, in particular, the Collins mechanism contributions in various hadronic reactions, such as semi-inclusive hadron production in DIS process, azimuthal distribution of hadron in high energy jet in pp collisions. We will demonstrate that the transverse momentum dependent and collinear factorization approaches are consistent with each other in the description of the Collins effects in the semi-inclusive hadron production in DIS process.

  11. Collins Mechanism Contributions to Single Spin Asymmetry

    SciTech Connect

    Yuan, Feng

    2009-09-11

    We present recent developments on the single transverse spin physics,in particular, the Collins mechanism contributions in various hadronic reactions,such as semi-inclusive hadron production in DIS process, azimuthal distributionof hadron in high energy jet in pp collisions. We will demonstrate thatthe transverse momentum dependent and collinear factorization approaches areconsistentwith each other in the description of the Collins effects in the semi-inclusivehadron production in DIS process.

  12. Single spins in diamond for quantum networks and magnetic sensing

    NASA Astrophysics Data System (ADS)

    Dutt, M. V. Gurudev

    2010-06-01

    Building scalable quantum information systems is a central challenge facing modern science. Single spins in diamond are a promising platform for distributed quantum information networks and precision measurements. I will discuss recent progress in this field demonstrating coherent operations with coupled electron-nuclear spin quantum registers and nanoscale precision magnetometry. Our experiments demonstrate addressing, preparation, and coherent control of individual nuclear spin qubits in the diamond lattice at room temperature. We have measured spin coherence times exceeding milliseconds, and observed coherent coupling to nearby electronic and nuclear spins. Robust initialization of a two-qubit register and transfer of arbitrary quantum states between electron and nuclear spin qubits has been achieved. Our results show that coherent operations are possible with individual solid-state qubits whose coherence properties approach those for isolated atoms and ions. The resulting electron-nuclear few-qubit registers can potentially serve as small processor nodes in a quantum network where the electron spins are coupled by optical photons.

  13. Nutation control during precession of a spin-stabilized spacecraft

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Precession maneuver control laws for single-spin spacecraft are investigated so that nutation is concurrently controlled. Analysis has led to the development of two types of control laws employing precession modulation for concurrent nutation control. Results were verified through digital simulation of a Synchronous Meteorological Satellite (SMS) configuration. An addition research effort was undertaken to investigate the cause and elimination of nutation anomalies in dual-spin spacecraft. A literature search was conducted and a dual-spin configuration was simulated to verify that nutational anomalies are not predicted by the existing nonlinear model. No conclusions were drawn as to the cause of the observed nutational anomalies in dual-spin spacecraft.

  14. Single Spin Asymmetries from a Single Wilson Loop.

    PubMed

    Boer, Daniël; Echevarria, Miguel G; Mulders, Piet J; Zhou, Jian

    2016-03-25

    We study the leading-power gluon transverse-momentum-dependent distributions (TMDs) of relevance to the study of asymmetries in the scattering off transversely polarized hadrons. Next-to-leading-order perturbative calculations of these TMDs show that at large transverse momentum they have common dynamical origins but that in the limit of a small longitudinal momentum fraction x, only one origin remains. We find that in this limit, only the dipole-type gluon TMDs survive and become identical to each other. At small x, they are all given by the expectation value of a single Wilson loop inside the transversely polarized hadron, the so-called spin-dependent odderon. This universal origin of transverse spin asymmetries at small x is of importance to current and future experimental studies, paving the way to a better understanding of the role of gluons in the three-dimensional structure of spin-polarized protons. PMID:27058070

  15. Ultrafast optical control of individual quantum dot spin qubits.

    PubMed

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

    2013-09-01

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

  16. Ultrafast optical control of individual quantum dot spin qubits.

    PubMed

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

    2013-09-01

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

  17. Measuring mechanical motion with a single spin

    NASA Astrophysics Data System (ADS)

    Bennett, S. D.; Kolkowitz, S.; Unterreithmeier, Q. P.; Rabl, P.; Bleszynski Jayich, A. C.; Harris, J. G. E.; Lukin, M. D.

    2012-12-01

    We study theoretically the measurement of a mechanical oscillator using a single two-level system as a detector. In a recent experiment, we used a single electronic spin associated with a nitrogen-vacancy center in diamond to probe the thermal motion of a magnetized cantilever at room temperature (Kolkowitz et al 2012 Science 335 1603). Here, we present a detailed analysis of the sensitivity limits of this technique, as well as the possibility to measure the zero-point motion of the oscillator. Further, we discuss the issue of measurement backaction in sequential measurements and find that although backaction heating can occur, it does not prohibit the detection of zero-point motion. Throughout the paper, we focus on the experimental implementation of a nitrogen-vacancy center coupled to a magnetic cantilever; however, our results are applicable to a wide class of spin-oscillator systems. The implications for the preparation of nonclassical states of a mechanical oscillator are also discussed.

  18. Theoretical Study of Interaction between Photons and Single Spins

    NASA Astrophysics Data System (ADS)

    Chen, Ting

    Spin is a promising candidate for new resources of information technology. The major applications of spin-based technology are quantum computation, quantum communication and high-sensitive magnetometry. Optical control and detection of spin coherence are important techniques for such applications. In quantum communication and distributed quantum computing, quantum networks consisting of local nodes which are connected by quantum channels are essential. They provide platforms for transmission of flying qubits from one node to another. Within physical implementation of such networks, local nodes consist of clusters of stationary qubits. A single photon can form the flying qubit. The quantum information carried by the flying qubits can be conducted between local nodes through waveguides. Therefore quantum interfacing is the key element for the scalability in the quantum network. In the first two chapters of the thesis, we focus on the strong coupling region of the quantum interfacing. Solid-state systems have the advantages of stability and integratability. In solid-state systems, one-dimensional waveguides serve as an outstanding medium for transporting photons. Waveguides provide suitable circumstance for the strong interaction between photons and atoms for the small interaction section. This strong coupling between the atom and waveguide allows the photons to be directionally emitted into one optical channel connecting different quantum nodes. First, we follow the control scheme of the interplay between a stationary qubit and a flying qubit at an interface, which is composed of a Λ-type system coupled to a one-dimensional waveguide. It shows that the sending and receiving process can be independently controlled by changing the driving laser pulses. We extend a general control scheme of a spin-photon quantum interface. Our scheme removes the constraints of Markovian process and therefore can be applied to the atom-waveguide devices for quantum network applications

  19. Ultrahigh spin thermopower and pure spin current in a single-molecule magnet

    PubMed Central

    Luo, Bo; Liu, Juan; Lü, Jing-Tao; Gao, Jin-Hua; Yao, Kai-Lun

    2014-01-01

    Using the non-equilibrium Green's function (NEGF) formalism within the sequential regime, we studied ultrahigh spin thermopower and pure spin current in single-molecule magnet(SMM), which is attached to nonmagnetic metal wires with spin bias and angle (θ) between the easy axis of SMM and the spin orientation in the electrodes. A pure spin current can be generated by tuning the gate voltage and temperature difference with finite spin bias and the arbitrary angle except of . In the linear regime, large thermopower can be obtained by modifying Vg and the angles (θ). These results are useful in fabricating and advantaging SMM devices based on spin caloritronics. PMID:24549224

  20. Nanosecond spin relaxation times in single layer graphene spin valves with hexagonal boron nitride tunnel barriers

    NASA Astrophysics Data System (ADS)

    Singh, Simranjeet; Katoch, Jyoti; Xu, Jinsong; Tan, Cheng; Zhu, Tiancong; Amamou, Walid; Hone, James; Kawakami, Roland

    2016-09-01

    We present an experimental study of spin transport in single layer graphene using atomic sheets of hexagonal boron nitride (h-BN) as a tunnel barrier for spin injection. While h-BN is expected to be favorable for spin injection, previous experimental studies have been unable to achieve spin relaxation times in the nanosecond regime, suggesting potential problems originating from the contacts. Here, we investigate spin relaxation in graphene spin valves with h-BN barriers and observe room temperature spin lifetimes in excess of a nanosecond, which provides experimental confirmation that h-BN is indeed a good barrier material for spin injection into graphene. By carrying out measurements with different thicknesses of h-BN, we show that few layer h-BN is a better choice than monolayer for achieving high non-local spin signals and longer spin relaxation times in graphene.

  1. Inelastic electron tunneling spectroscopy of a single nuclear spin.

    PubMed

    Delgado, F; Fernández-Rossier, J

    2011-08-12

    Detection of a single nuclear spin constitutes an outstanding problem in different fields of physics such as quantum computing or magnetic imaging. Here we show that the energy levels of a single nuclear spin can be measured by means of inelastic electron tunneling spectroscopy (IETS). We consider two different systems, a magnetic adatom probed with scanning tunneling microscopy and a single Bi dopant in a silicon nanotransistor. We find that the hyperfine coupling opens new transport channels which can be resolved at experimentally accessible temperatures. Our simulations evince that IETS yields information about the occupations of the nuclear spin states, paving the way towards transport-detected single nuclear spin resonance.

  2. Single transverse-spin asymmetry in QCD

    NASA Astrophysics Data System (ADS)

    Koike, Yuji

    2014-09-01

    So far large single transverse-spin asymmetries (SSA) have been observed in many high-energy processes such as semi-inclusive deep inelastic scattering and proton-proton collisions. Since the conventional parton model and perturbative QCD can not accomodate such large SSAs, the framework for QCD hard processes had to be extended to understand the mechanism of SSA. In this extended frameworks of QCD, intrinsic transverse momentum of partons and the multi-parton (quark-gluon and pure-gluonic) correlations in the hadrons, which were absent in the conventional framework, play a crucial role to cause SSAs, and well-defined formulation of these effects has been a big challenge for QCD theorists. Study on these effects has greatly promoted our understanding on QCD dynamics and hadron structure. In this talk, I will present an overview on these theoretical activity, emphasizing the important role of the Drell-Yan process.

  3. Spin Hall controlled magnonic microwaveguides

    SciTech Connect

    Demidov, V. E.; Urazhdin, S.; Rinkevich, A. B.; Reiss, G.; Demokritov, S. O.

    2014-04-14

    We use space-resolved magneto-optical spectroscopy to study the influence of spin Hall effect on the excitation and propagation of spin waves in microscopic magnonic waveguides. We find that the spin Hall effect not only increases the spin-wave propagation length, but also results in an increased excitation efficiency due to the increase of the dynamic susceptibility in the vicinity of the inductive antenna. We show that the efficiency of the propagation length enhancement is strongly dependant on the type of the excited spin-wave mode and its wavelength.

  4. Single spin magnetometry with nitrogen-vacancy centers in diamond

    NASA Astrophysics Data System (ADS)

    Chisholm, Nicholas Edward Kennedy

    The nitrogen-vacancy (NV) center in diamond is a solid-state point defect with an electronic spin that has accessible quantum mechanical properties. At room temperature, the electronic ground state sub-levels of the NV center can be initialized and read out using optical pumping, as well as coherently controlled using microwave frequency fields. This thesis focuses on using the spin state of the NV center for highly-sensitive magnetometry under ambient conditions. In particular, when the diamond surface is properly prepared, we demonstrate that NV centers can be used to measure the magnetic fluctuations stemming from individual molecules and ions attached or adsorbed to the surface. This thesis begins by introducing the physical and electronic structure of the NV center at room temperature, followed by the fundamental measurements that allow us to use the NV center as a sensitive magnetometer. Combining our sensitive NV center magnetometer with techniques from chemistry and atomic force microscopy (AFM), we demonstrate the all-optical detection of a single-molecule electron spin at room temperature. Finally, we discuss the time-resolved detection of individual electron spins adsorbing onto the surface of nano-diamonds. By extending our techniques to nano-diamonds, we move closer towards textit{in vitro} magnetic field sensing that could be pivotal for better disease diagnosis and drug development.

  5. RHIC spin flipper AC dipole controller

    SciTech Connect

    Oddo, P.; Bai, M.; Dawson, C.; Gassner, D.; Harvey, M.; Hayes, T.; Mernick, K.; Minty, M.; Roser, T.; Severino, F.; Smith, K.

    2011-03-28

    The RHIC Spin Flipper's five high-Q AC dipoles which are driven by a swept frequency waveform require precise control of phase and amplitude during the sweep. This control is achieved using FPGA based feedback controllers. Multiple feedback loops are used to and dynamically tune the magnets. The current implementation and results will be presented. Work on a new spin flipper for RHIC (Relativistic Heavy Ion Collider) incorporating multiple dynamically tuned high-Q AC-dipoles has been developed for RHIC spin-physics experiments. A spin flipper is needed to cancel systematic errors by reversing the spin direction of the two colliding beams multiple times during a store. The spin flipper system consists of four DC-dipole magnets (spin rotators) and five AC-dipole magnets. Multiple AC-dipoles are needed to localize the driven coherent betatron oscillation inside the spin flipper. Operationally the AC-dipoles form two swept frequency bumps that minimize the effect of the AC-dipole dipoles outside of the spin flipper. Both AC bumps operate at the same frequency, but are phase shifted from each other. The AC-dipoles therefore require precise control over amplitude and phase making the implementation of the AC-dipole controller the central challenge.

  6. Macroscopic rotation of photon polarization induced by a single spin.

    PubMed

    Arnold, Christophe; Demory, Justin; Loo, Vivien; Lemaître, Aristide; Sagnes, Isabelle; Glazov, Mikhaïl; Krebs, Olivier; Voisin, Paul; Senellart, Pascale; Lanco, Loïc

    2015-01-01

    Entangling a single spin to the polarization of a single incoming photon, generated by an external source, would open new paradigms in quantum optics such as delayed-photon entanglement, deterministic logic gates or fault-tolerant quantum computing. These perspectives rely on the possibility that a single spin induces a macroscopic rotation of a photon polarization. Such polarization rotations induced by single spins were recently observed, yet limited to a few 10(-3) degrees due to poor spin-photon coupling. Here we report the enhancement by three orders of magnitude of the spin-photon interaction, using a cavity quantum electrodynamics device. A single hole spin in a semiconductor quantum dot is deterministically coupled to a micropillar cavity. The cavity-enhanced coupling between the incoming photons and the solid-state spin results in a polarization rotation by ± 6° when the spin is optically initialized in the up or down state. These results open the way towards a spin-based quantum network. PMID:25687134

  7. Pumped Spin-Current in Single Quantum Dot with Spin-Dependent Electron Temperature

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Wang, Song; Du, Xiaohong

    2016-09-01

    Spin-dependent electron temperature effect on the spin pump in a single quantum dot connected to Normal and/or Ferromagnetic leads are investigated with the help of master equation method. Results show that spin heat accumulation breaks the tunneling rates balance at the thermal equilibrium state thus the charge current and the spin current are affected to some extent. Pure spin current can be obtained by adjusting pumping intensity or chemical potential of the lead. Spin heat accumulation of certain material can be detected by measuring the charge current strength in symmetric leads architectures. In practical devices, spin-dependent electron temperature effect is quite significant and our results should be useful in quantum information processing and spin Caloritronics.

  8. Spin control of light with hyperbolic metasurfaces

    NASA Astrophysics Data System (ADS)

    Yermakov, Oleh Y.; Ovcharenko, Anton I.; Bogdanov, Andrey A.; Iorsh, Ivan V.; Bliokh, Konstantin Y.; Kivshar, Yuri S.

    2016-08-01

    Transverse spin angular momentum is an inherent feature of evanescent waves which may have applications in nanoscale optomechanics, spintronics, and quantum information technology due to the robust spin-directional coupling. Here we analyze local spin angular momentum density of hybrid surface waves propagating along anisotropic hyperbolic metasurfaces. We reveal that, in contrast to bulk plane waves and conventional surface plasmons at isotropic interfaces, the spin of the hybrid surface waves can be engineered to have an arbitrary angle with the propagation direction. This property allows us to tailor directivity of surface waves via the magnetic control of the spin projection of quantum emitters, and it can be useful for optically controlled spin transfer.

  9. Precise quantum control on solid-state spins

    NASA Astrophysics Data System (ADS)

    Geng, Jianpei

    Precise quantum control is of great importance for quantum information processing, high resolution spectroscopy, and quantum metrology. One of the key obstacles to realizing precise quantum control on solid-state spins is the noises arising from both environment and control field. Here, we design a composite pulse to realize precise quantum control on a single electron spin in diamond by suppressing the effect of both noises simultaneously. The control is experimentally demonstrated to be with a low error rate of 4.8E-5. We improve quantum optimal control method to realize precise two-qubit quantum control on a system comprised by a single electron spin and 14N nuclear spin. With the improved quantum optimal control method, we design a pulse sequence for CNOT gate to suppress the noises simultaneously. The error rate of CNOT gate is measured to be 8E-3. To the best of our knowledge, the control we have realized stands for the state of art in precise quantum control on solid-state spins.

  10. Clocked single-spin source based on a spin-split superconductor

    NASA Astrophysics Data System (ADS)

    Dittmann, Niklas; Splettstoesser, Janine; Giazotto, Francesco

    2016-08-01

    We propose an accurate clocked single-spin source for ac-spintronic applications. Our device consists of a superconducting island covered by a ferromagnetic insulator (FI) layer through which it is coupled to superconducting leads. Single-particle transfer relies on the energy gaps and the island's charging energy, and is enabled by a bias and a time-periodic gate voltage. Accurate spin transfer is achieved by the FI layer which polarizes the island, provides spin-selective tunneling barriers and improves the precision by suppressing Andreev reflection. We analyze realistic material combinations and experimental requirements which allow for a clocked spin current in the MHz regime.

  11. Electrons trapped in single crystals of sucrose: Induced spin densities

    SciTech Connect

    Box, H.C.; Budzinski, E.E.; Freund, H.G. )

    1990-07-01

    Electrons are trapped at intermolecular sites in single crystals of sucrose {ital X} irradiated at 4.2 K. The coupling tensors for the hyperfine couplings between the electron and surrounding protons have been deduced from electron-nuclear double resonance (ENDOR) data. Electron spin densities at nearby hydroxy protons are positive, whereas spin densities at the more remote protons of carbon-bound hydrogen atoms are negative. The origin of these negative spin densities is discussed.

  12. Electrons trapped in single crystals of sucrose: Induced spin densities

    NASA Astrophysics Data System (ADS)

    Box, Harold C.; Budzinski, Edwin E.; Freund, Harold G.

    1990-07-01

    Electrons are trapped at intermolecular sites in single crystals of sucrose X irradiated at 4.2 K. The coupling tensors for the hyperfine couplings between the electron and surrounding protons have been deduced from electron-nuclear double resonance (ENDOR) data. Electron spin densities at nearby hydroxy protons are positive, whereas spin densities at the more remote protons of carbon-bound hydrogen atoms are negative. The origin of these negative spin densities is discussed.

  13. Spin resonance strength calculation through single particle tracking for RHIC

    SciTech Connect

    Luo, Y.; Dutheil, Y.; Huang, H.; Meot, F.; Ranjbar, V.

    2015-05-03

    The strengths of spin resonances for the polarized-proton operation in the Relativistic Heavy Ion Collider are currently calculated with the code DEPOL, which numerically integrates through the ring based on an analytical approximate formula. In this article, we test a new way to calculate the spin resonance strengths by performing Fourier transformation to the actual transverse magnetic fields seen by a single particle traveling through the ring. Comparison of calculated spin resonance strengths is made between this method and DEPOL.

  14. Single Spin Asymmetry in Strongly Correlated Quark Model

    SciTech Connect

    Musulmanbekov, G.

    2007-06-13

    The Single Transverse - Spin Asymmetry (SSA) is analysed in the framework of the Strongly Correlated Quark Model proposed by author, where the proton spin emerges from the orbital momenta of quark and qluon condensates circulating around the valence quarks. It is shown that dominating factors of appearance of SSA are the orbiting around the valence quarks sea quark and qluon condensates and spin dependent quark-quark cross sections.

  15. Spin Parity effects in STM single magnetic atom manipulation

    NASA Astrophysics Data System (ADS)

    Delgado, Fernando; Fernández-Rossier, Joaquín

    2012-02-01

    Recent experimental work shows that a spin polarized scanning tunneling microscopy tip can be used both to read and write the spin orientation of a single magnetic spin [1]. Inelastic electron tunneling spectroscopy (IETS) shows that spin of the magnetic atom is quantized [2], like the spin of a molecular magnet. Here we discuss two fundamental problems that arise when a bit of classical information is stored on a quantized spin: quantum spin tunneling and back-action of the readout process. Quantum tunneling is responsible of the loss of information due to the relaxation of the spin coupled to the environment, while the detection induced back-action leads to an unwanted modification of the spin state. We find that fundamental differences exist between integer and semi-integer spins when it comes to both, read and write classical information in a quantized spin.[4pt] [1] S. Loth et al, Nature Physics 6, 340 (2010).[0pt] [2] C. Hirjibehedin et al, Science 317, 1199 (2007).

  16. Spin Stabilized Impulsively Controlled Missile (SSICM)

    NASA Astrophysics Data System (ADS)

    Crawford, J. I.; Howell, W. M.

    1985-12-01

    This patent is for the Spin Stabilized Impulsively Controlled Missile (SSICM). SSICM is a missile configuration which employs spin stabilization, nutational motion, and impulsive thrusting, and a body mounted passive or semiactive sensor to achieve very small miss distances against a high speed moving target. SSICM does not contain an autopilot, control surfaces, a control actuation system, nor sensor stabilization gimbals. SSICM spins at a rate sufficient to provide frequency separation between body motions and inertial target motion. Its impulsive thrusters provide near instantaneous changes in lateral velocity, whereas conventional missiles require a significant time delay to achieve lateral acceleration.

  17. Detection of atomic spin labels in a lipid bilayer using a single-spin nanodiamond probe

    PubMed Central

    Kaufmann, Stefan; Simpson, David A.; Hall, Liam T.; Perunicic, Viktor; Senn, Philipp; Steinert, Steffen; McGuinness, Liam P.; Johnson, Brett C.; Ohshima, Takeshi; Caruso, Frank; Wrachtrup, Jörg; Scholten, Robert E.; Mulvaney, Paul; Hollenberg, Lloyd

    2013-01-01

    Magnetic field fluctuations arising from fundamental spins are ubiquitous in nanoscale biology, and are a rich source of information about the processes that generate them. However, the ability to detect the few spins involved without averaging over large ensembles has remained elusive. Here, we demonstrate the detection of gadolinium spin labels in an artificial cell membrane under ambient conditions using a single-spin nanodiamond sensor. Changes in the spin relaxation time of the sensor located in the lipid bilayer were optically detected and found to be sensitive to near-individual (4 ± 2) proximal gadolinium atomic labels. The detection of such small numbers of spins in a model biological setting, with projected detection times of 1 s [corresponding to a sensitivity of ∼5 Gd spins per Hz1/2], opens a pathway for in situ nanoscale detection of dynamical processes in biology. PMID:23776230

  18. Quantum control and squeezing of collective spins

    NASA Astrophysics Data System (ADS)

    Montano, Enrique

    Quantum control of many body atomic spins is often pursued in the context of an atom-light quantum interface, where a quantized light field acts as a "quantum bus" that can be used to entangle distant atoms. One key challenge is to improve the coherence of the atom-light interface and the amount of atom-light entanglement it can generate, given the constraints of working with multilevel atoms and optical fields in a 3D geometry. We have explored new ways to achieve this, through rigorous optimization of the spatial geometry, and through control of the internal atomic state. Our basic setup consists of a quantized probe beam passing through an atom cloud held in a dipole trap, first generating spin-probe entanglement through the Faraday interaction, and then using backaction from a measurement of the probe polarization to squeeze the collective atomic spin. The relevant figure of merit is the metrologically useful spin squeezing determined by the enhancement in the resolution of rotations of the collective spin, relative to the commonly used spin coherent state. With an optimized free-space geometry, and by using a 2-color probe scheme to suppress tensor light shifts, we achieve 3(2) dB of metrologically useful spin squeezing. We can further increase atom-light coupling by implementing internal state control to prepare spin states with larger initial projection noise relative to the spin coherent state. Under the right conditions this increase in projection noise can lead to stronger measurement backaction and increased atom-atom entanglement. With further internal state control the increased atom-atom entanglement can then be mapped to a basis where it corresponds to improved squeezing of, e.g., the physical spin-angular momentum or the collective atomic clock pseudospin. In practice, controlling the collective spin of N ~ 106 atoms in this fashion is an extraordinarily difficult challenge because errors in the control of individual atoms tend to be highly

  19. Engineering near-infrared single-photon emitters with optically active spins in ultrapure silicon carbide

    NASA Astrophysics Data System (ADS)

    Fuchs, F.; Stender, B.; Trupke, M.; Simin, D.; Pflaum, J.; Dyakonov, V.; Astakhov, G. V.

    2015-07-01

    Vacancy-related centres in silicon carbide are attracting growing attention because of their appealing optical and spin properties. These atomic-scale defects can be created using electron or neutron irradiation; however, their precise engineering has not been demonstrated yet. Here, silicon vacancies are generated in a nuclear reactor and their density is controlled over eight orders of magnitude within an accuracy down to a single vacancy level. An isolated silicon vacancy serves as a near-infrared photostable single-photon emitter, operating even at room temperature. The vacancy spins can be manipulated using an optically detected magnetic resonance technique, and we determine the transition rates and absorption cross-section, describing the intensity-dependent photophysics of these emitters. The on-demand engineering of optically active spins in technologically friendly materials is a crucial step toward implementation of both maser amplifiers, requiring high-density spin ensembles, and qubits based on single spins.

  20. Engineering near-infrared single-photon emitters with optically active spins in ultrapure silicon carbide.

    PubMed

    Fuchs, F; Stender, B; Trupke, M; Simin, D; Pflaum, J; Dyakonov, V; Astakhov, G V

    2015-07-07

    Vacancy-related centres in silicon carbide are attracting growing attention because of their appealing optical and spin properties. These atomic-scale defects can be created using electron or neutron irradiation; however, their precise engineering has not been demonstrated yet. Here, silicon vacancies are generated in a nuclear reactor and their density is controlled over eight orders of magnitude within an accuracy down to a single vacancy level. An isolated silicon vacancy serves as a near-infrared photostable single-photon emitter, operating even at room temperature. The vacancy spins can be manipulated using an optically detected magnetic resonance technique, and we determine the transition rates and absorption cross-section, describing the intensity-dependent photophysics of these emitters. The on-demand engineering of optically active spins in technologically friendly materials is a crucial step toward implementation of both maser amplifiers, requiring high-density spin ensembles, and qubits based on single spins.

  1. Transverse single-spin asymmetries: Challenges and recent progress

    SciTech Connect

    Metz, Andreas; Pitonyak, Daniel; Schafer, Andreas; Schlegel, Marc; Vogelsang, Werner; Zhou, Jian

    2014-11-25

    In this study, transverse single-spin asymmetries are among the most intriguing observables in hadronic physics. Though such asymmetries were already measured for the first time about four decades ago, their origin is still under debate. Here we consider transverse single-spin asymmetries in semi-inclusive lepton–nucleon scattering, in nucleon–nucleon scattering, and in inclusive lepton–nucleon scattering. It is argued that, according to recent work, the single-spin asymmetries for those three processes may be simultaneously described in perturbative QCD, where the re-scattering of the active partons plays a crucial role. A comparison of single-spin asymmetries in different reactions can also shed light on the universality of transverse momentum dependent parton correlation functions. In particular, we discuss what existing data may tell us about the predicted process dependence of the Sivers function.

  2. Transverse single-spin asymmetries: Challenges and recent progress

    DOE PAGES

    Metz, Andreas; Pitonyak, Daniel; Schafer, Andreas; Schlegel, Marc; Vogelsang, Werner; Zhou, Jian

    2014-11-25

    In this study, transverse single-spin asymmetries are among the most intriguing observables in hadronic physics. Though such asymmetries were already measured for the first time about four decades ago, their origin is still under debate. Here we consider transverse single-spin asymmetries in semi-inclusive lepton–nucleon scattering, in nucleon–nucleon scattering, and in inclusive lepton–nucleon scattering. It is argued that, according to recent work, the single-spin asymmetries for those three processes may be simultaneously described in perturbative QCD, where the re-scattering of the active partons plays a crucial role. A comparison of single-spin asymmetries in different reactions can also shed light on themore » universality of transverse momentum dependent parton correlation functions. In particular, we discuss what existing data may tell us about the predicted process dependence of the Sivers function.« less

  3. Collins Fragmentation and the Single Transverse Spin Asymmetry

    SciTech Connect

    Yuan, Feng; Zhou, Jian

    2009-03-26

    We study the Collins mechanism for the single transverse spin asymmetry in the collinear factorization approach. The correspondent twist-three fragmentation function is identified. We show that the Collins function calculated in this approach is universal.We further examine its contribution to the single transverse spin asymmetry of semi-inclusive hadron production in deep inelastic scattering and demonstrate that the transverse momentum dependent and twist-three collinear approaches are consistent in the intermediate transverse momentum region where both apply.

  4. Large Conductance Switching in a Single-Molecule Device through Room Temperature Spin-Dependent Transport.

    PubMed

    Aragonès, Albert C; Aravena, Daniel; Cerdá, Jorge I; Acís-Castillo, Zulema; Li, Haipeng; Real, José Antonio; Sanz, Fausto; Hihath, Josh; Ruiz, Eliseo; Díez-Pérez, Ismael

    2016-01-13

    Controlling the spin of electrons in nanoscale electronic devices is one of the most promising topics aiming at developing devices with rapid and high density information storage capabilities. The interface magnetism or spinterface resulting from the interaction between a magnetic molecule and a metal surface, or vice versa, has become a key ingredient in creating nanoscale molecular devices with novel functionalities. Here, we present a single-molecule wire that displays large (>10000%) conductance switching by controlling the spin-dependent transport under ambient conditions (room temperature in a liquid cell). The molecular wire is built by trapping individual spin crossover Fe(II) complexes between one Au electrode and one ferromagnetic Ni electrode in an organic liquid medium. Large changes in the single-molecule conductance (>100-fold) are measured when the electrons flow from the Au electrode to either an α-up or a β-down spin-polarized Ni electrode. Our calculations show that the current flowing through such an interface appears to be strongly spin-polarized, thus resulting in the observed switching of the single-molecule wire conductance. The observation of such a high spin-dependent conductance switching in a single-molecule wire opens up a new door for the design and control of spin-polarized transport in nanoscale molecular devices at room temperature. PMID:26675052

  5. Nuclear magnetic resonance spectroscopy with single spin sensitivity.

    PubMed

    Müller, C; Kong, X; Cai, J-M; Melentijević, K; Stacey, A; Markham, M; Twitchen, D; Isoya, J; Pezzagna, S; Meijer, J; Du, J F; Plenio, M B; Naydenov, B; McGuinness, L P; Jelezko, F

    2014-08-22

    Nuclear magnetic resonance spectroscopy and magnetic resonance imaging at the ultimate sensitivity limit of single molecules or single nuclear spins requires fundamentally new detection strategies. The strong coupling regime, when interaction between sensor and sample spins dominates all other interactions, is one such strategy. In this regime, classically forbidden detection of completely unpolarized nuclei is allowed, going beyond statistical fluctuations in magnetization. Here we realize strong coupling between an atomic (nitrogen-vacancy) sensor and sample nuclei to perform nuclear magnetic resonance on four (29)Si spins. We exploit the field gradient created by the diamond atomic sensor, in concert with compressed sensing, to realize imaging protocols, enabling individual nuclei to be located with Angstrom precision. The achieved signal-to-noise ratio under ambient conditions allows single nuclear spin sensitivity to be achieved within seconds.

  6. Charge noise, spin-orbit coupling, and dephasing of single-spin qubits

    SciTech Connect

    Bermeister, Adam; Keith, Daniel; Culcer, Dimitrie

    2014-11-10

    Quantum dot quantum computing architectures rely on systems in which inversion symmetry is broken, and spin-orbit coupling is present, causing even single-spin qubits to be susceptible to charge noise. We derive an effective Hamiltonian for the combined action of noise and spin-orbit coupling on a single-spin qubit, identify the mechanisms behind dephasing, and estimate the free induction decay dephasing times T{sub 2}{sup *} for common materials such as Si and GaAs. Dephasing is driven by noise matrix elements that cause relative fluctuations between orbital levels, which are dominated by screened whole charge defects and unscreened dipole defects in the substrate. Dephasing times T{sub 2}{sup *} differ markedly between materials and can be enhanced by increasing gate fields, choosing materials with weak spin-orbit, making dots narrower, or using accumulation dots.

  7. Quantum Entanglement and Spin Control in Silicon Nanocrystal

    PubMed Central

    Berec, Vesna

    2012-01-01

    Selective coherence control and electrically mediated exchange coupling of single electron spin between triplet and singlet states using numerically derived optimal control of proton pulses is demonstrated. We obtained spatial confinement below size of the Bohr radius for proton spin chain FWHM. Precise manipulation of individual spins and polarization of electron spin states are analyzed via proton induced emission and controlled population of energy shells in pure 29Si nanocrystal. Entangled quantum states of channeled proton trajectories are mapped in transverse and angular phase space of 29Si axial channel alignment in order to avoid transversal excitations. Proton density and proton energy as impact parameter functions are characterized in single particle density matrix via discretization of diagonal and nearest off-diagonal elements. We combined high field and low densities (1 MeV/92 nm) to create inseparable quantum state by superimposing the hyperpolarizationed proton spin chain with electron spin of 29Si. Quantum discretization of density of states (DOS) was performed by the Monte Carlo simulation method using numerical solutions of proton equations of motion. Distribution of gaussian coherent states is obtained by continuous modulation of individual spin phase and amplitude. Obtained results allow precise engineering and faithful mapping of spin states. This would provide the effective quantum key distribution (QKD) and transmission of quantum information over remote distances between quantum memory centers for scalable quantum communication network. Furthermore, obtained results give insights in application of channeled protons subatomic microscopy as a complete versatile scanning-probe system capable of both quantum engineering of charged particle states and characterization of quantum states below diffraction limit linear and in-depth resolution. PACS numbers: 03.65.Ud, 03.67.Bg, 61.85.+p, 67.30.hj PMID:23028884

  8. Single molecule spin resonance spectroscopy and imaging by diamond-sensor

    NASA Astrophysics Data System (ADS)

    Du, Jiangfeng

    Single-molecule magnetic resonance spectroscopy and imaging is one of the ultimate goals in magnetic resonance and will has great applications in a broad range of scientific areas, from life science to physics and chemistry. The spin of a single nitrogen vacancy (NV) center in diamond is a highly sensitive magnetic-field sensor, which has been proposed for detection of single molecules or nanoscale targets. We and co-workers have successfully obtained the first single-protein spin resonance spectroscopy under ambient conditions, high-resolution vector microwave imaging, and realized atomic-scale structure analysis of single nuclear-spin clusters in diamond. Moreover, we have tried to improve the quantum control technique and succeed to achieve fault-tolerant universal quantum gates. As the last part, I will briefly introduce our most recently work on single protein imaging in situ in cell.

  9. Spectral control of spin qubits in diamond photonic structures

    NASA Astrophysics Data System (ADS)

    Acosta, Victor; Santori, Charles; Faraon, Andrei; Huang, Zhihong; Beausoleil, Raymond

    2012-06-01

    Integrated photonic networks based on cavity-coupled spin impurities offer a promising platform for scalable quantum computing. A key ingredient for this technology involves heralding entanglement by interfering indistinguishable photons emitted by pairs of identical spin qubits. The nitrogen-vacancy (NV) center in diamond is an attractive candidate for such a spin-photon interface, as it exhibits long-lived electronic spin coherence, rapid spin manipulation and readout, and the coexistence of both robust cycling and spin-altering Lambda-type transitions. We discuss current research in our lab to control the spectral properties of single NV centers by dynamic Stark tuning [1] and cavity Purcell enhancement [2]. In particular, we report progress on fabricating photonic structures in ultra-pure diamond, where NV centers are likely to have favorable optical properties. [4pt] [1] V. M. Acosta et al., Dynamic stabilization of the optical resonances of single nitrogen-vacancy centers in diamond, arXiv:1112.5490v1 [quant-ph]. [0pt] [2] A. Faraon et al., Coupling of nitrogen-vacancy centers to photonic crystal cavities in monocrystalline diamond, Submitted.

  10. Attitude orientation control for a spinning satellite

    NASA Astrophysics Data System (ADS)

    Frost, Gerald

    The Department of the Air Force, Headquarters Space Systems Division, and the National Aeronautics and Space Administration (NASA) are currently involved in litigation with Hughes Aircraft Company over the alledged infringement of the 'Williams patent,' which describes a method for attitude control of a spin-stabilized vehicle. Summarized here is pre-1960 RAND work on this subject and information obtained from RAND personnel knowledgeable on this subject. It was concluded that there is no RAND documentation that directly parallels the 'Williams patent' concept. Also, the TIROS II magnetic torque attitude control method is reviewed. The TIROS II meteorological satellite, launched on November 23, 1960, incorporated a magnetic actuation system for spin axis orientation control. The activation system was ground controlled to orient the satellite spin axis to obtain the desired pointing direction for optical and infrared sensor subsystems.

  11. Single hadron transverse spin asymmetries from COMPASS

    SciTech Connect

    Bradamante, Franco

    2007-06-13

    Transverse spin physics is an important part of the scientific programme of the COMPASS experiment at CERN. The analysis of the data taken with the target polarized orthogonally to the 160 GeV/c muon beam momentum has allowed to measure for the first time the Collins and Sivers asymmetries of the deuteron. Both for the positive and the negative hadrons produced in semi-inclusive DIS the measured asymmetries are small and, within errors, compatible with zero. New results for {pi}{+-} ans K{+-} are presented here.

  12. Observation of Spin Flips with a Single Trapped Proton

    SciTech Connect

    Ulmer, S.; Rodegheri, C. C.; Blaum, K.; Kracke, H.; Mooser, A.; Walz, J.; Quint, W.

    2011-06-24

    Radio-frequency induced spin transitions of one individual proton are observed. The spin quantum jumps are detected via the continuous Stern-Gerlach effect, which is used in an experiment with a single proton stored in a cryogenic Penning trap. This is an important milestone towards a direct high-precision measurement of the magnetic moment of the proton and a new test of the matter-antimatter symmetry in the baryon sector.

  13. High spin rate magnetic controller for nanosatellites

    NASA Astrophysics Data System (ADS)

    Slavinskis, A.; Kvell, U.; Kulu, E.; Sünter, I.; Kuuste, H.; Lätt, S.; Voormansik, K.; Noorma, M.

    2014-02-01

    This paper presents a study of a high rate closed-loop spin controller that uses only electromagnetic coils as actuators. The controller is able to perform spin rate control and simultaneously align the spin axis with the Earth's inertial reference frame. It is implemented, optimised and simulated for a 1-unit CubeSat ESTCube-1 to fulfil its mission requirements: spin the satellite up to 360 deg s-1 around the z-axis and align its spin axis with the Earth's polar axis with a pointing error of less than 3°. The attitude of the satellite is determined using a magnetic field vector, a Sun vector and angular velocity. It is estimated using an Unscented Kalman Filter and controlled using three electromagnetic coils. The algorithm is tested in a simulation environment that includes models of space environment and environmental disturbances, sensor and actuator emulation, attitude estimation, and a model to simulate the time delay caused by on-board calculations. In addition to the normal operation mode, analyses of reduced satellite functionality are performed: significant errors of attitude estimation due to non-operational Sun sensors; and limited actuator functionality due to two non-operational coils. A hardware-in-the-loop test is also performed to verify on-board software.

  14. Gaussian approximation and single-spin measurement in magnetic resonance force microscopy with spin noise

    SciTech Connect

    Raghunathan, Shesha; Brun, Todd A.; Goan, Hsi-Sheng

    2010-11-15

    A promising technique for measuring single electron spins is magnetic resonance force microscopy (MRFM), in which a microcantilever with a permanent magnetic tip is resonantly driven by a single oscillating spin. The most effective experimental technique is the oscillating cantilever-driven adiabatic reversals (OSCAR) protocol, in which the signal takes the form of a frequency shift. If the quality factor of the cantilever is high enough, this signal will be amplified over time to the point where it can be detected by optical or other techniques. An important requirement, however, is that this measurement process occurs on a time scale that is short compared to any noise which disturbs the orientation of the measured spin. We describe a model of spin noise for the MRFM system and show how this noise is transformed to become time dependent in going to the usual rotating frame. We simplify the description of the cantilever-spin system by approximating the cantilever wave function as a Gaussian wave packet and show that the resulting approximation closely matches the full quantum behavior. We then examine the problem of detecting the signal for a cantilever with thermal noise and spin with spin noise, deriving a condition for this to be a useful measurement.

  15. Nanoscale control of individual proximal NV spins via a scanning magnetic field-gradient

    NASA Astrophysics Data System (ADS)

    Grinolds, Michael; Maletinsky, Patrick; Hong, Sungkun; Lukin, Mikhail; Walsworth, Ronald; Yacoby, Amir

    2011-03-01

    Nanoscale ensembles of nitrogen-vacancy (NV) spins have been proposed for implementing quantum information protocols as well as performing sensitive nanoscale magnetometry. However, it has proven experimentally difficult to control individual NV spins without affecting the state of other, proximal spins, as spins are read-out optically and are often collectively driven by applied radio-frequency fields. We demonstrate that single-spin control in NV-spin ensembles can be achieved via a scanning magnetic field-gradient, which locally splits the electron spin resonances of proximal NVs. With this method, we achieve 9 nm spatial resolutions in imaging, characterization, and simultaneous manipulation of individual NVs, roughly two orders of magnitude better than the optical diffraction limit. We discuss applications of this individual control such as generating entangled spin-states and performing sensitive magnetometry.

  16. Enhanced Spin Hall Effect by Single Antidot Potential

    NASA Astrophysics Data System (ADS)

    Eto, Mikio; Yokoyama, Tomohiro

    2009-03-01

    We theoretically investigate an extrinsic spin Hall effect in semiconductor heterostructures due to the scattering by an artificial potential created by a single antidot, STM tip, etc. The strength of the potential is electrically tunable. First, we formulate the spin Hall effect in terms of phase shifts in the partial wave expansion for two-dimensional electron gas. For scattered electrons in θ direction, we obtain a spin polarization P(θ) perpendicular to the two-dimensional plane [P(-θ)=-P (θ)]. The spin polarization P(θ) is significantly enhanced by an attractive potential when the resonant condition of a partial wave is satisfied by tuning the potential strength. Second, we study the spin Hall effect in a three-terminal device with an antidot at the junction. The conductance and spin polarization are evaluated numerically.ootnotetextM. Yamamoto and B. Kramer, J. Appl. Phys. 103, 123703 (2008), for repulsive potential. We obtain a spin polarization of more than 50% due to the resonant scattering when the attractive potential is properly tuned.

  17. Controlling Spin Current in a Trapped Fermi Gas

    SciTech Connect

    Du, X.; Zhang, Y.; Petricka, J.; Thomas, J. E.

    2009-07-03

    We study fundamental features of spin current in a very weakly interacting Fermi gas of {sup 6}Li. By creating a spin current and then reversing its flow, we demonstrate control of the spin current. This reversal is predicted by a spin vector evolution equation in energy representation, which shows how the spin and energy of individual atoms become correlated in the nearly undamped regime of the experiments. The theory provides a simple physical description of the spin current and explains both the large amplitude and the slow temporal evolution of the data. Our results have applications in studying and controlling fundamental spin interactions and spin currents in ultracold gases.

  18. Single-Spin Asymmetries and Transversity in QCD

    SciTech Connect

    Brodsky, S.J.; /SLAC

    2005-12-14

    Initial- and final-state interactions from gluon exchange, normally neglected in the parton model, have a profound effect in QCD hard-scattering reactions, leading to leading-twist single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, as well as nuclear shadowing and antishadowing-leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. The physics of such processes thus require the understanding of QCD at the amplitude level; in particular, the physics of spin requires an understanding of the phase structure of final-state and initial-state interactions, as well as the structure of the basic wavefunctions of hadrons themselves. I also discuss transversity in exclusive channels, including how one can use single-spin asymmetries to determine the relative phases of the timelike baryon form factors, as well as the anomalous physics of the normal-normal spin-spin correlation observed in large-angle proton-proton elastic scattering. As an illustration of the utility of light-front wavefunctions, the transversity distribution of a single electron is computed, as defined from its two-particle QED quantum fluctuations.

  19. Spin-Orbit Twisted Spin Waves: Group Velocity Control

    NASA Astrophysics Data System (ADS)

    Perez, F.; Baboux, F.; Ullrich, C. A.; D'Amico, I.; Vignale, G.; Karczewski, G.; Wojtowicz, T.

    2016-09-01

    We present a theoretical and experimental study of the interplay between spin-orbit coupling (SOC), Coulomb interaction, and motion of conduction electrons in a magnetized two-dimensional electron gas. Via a transformation of the many-body Hamiltonian we introduce the concept of spin-orbit twisted spin waves, whose energy dispersions and damping rates are obtained by a simple wave-vector shift of the spin waves without SOC. These theoretical predictions are validated by Raman scattering measurements. With optical gating of the density, we vary the strength of the SOC to alter the group velocity of the spin wave. The findings presented here differ from that of spin systems subject to the Dzyaloshinskii-Moriya interaction. Our results pave the way for novel applications in spin-wave routing devices and for the realization of lenses for spin waves.

  20. Matrix Formalism for Spin Dynamics Near a Single Depolarization Resonance

    SciTech Connect

    Chao, Alexander W.; /SLAC

    2005-10-26

    A matrix formalism is developed to describe the spin dynamics in a synchrotron near a single depolarization resonance as the particle energy (and therefore its spin precession frequency) is varied in a prescribed pattern as a function of time such as during acceleration. This formalism is first applied to the case of crossing the resonance with a constant crossing speed and a finite total step size, and then applied also to other more involved cases when the single resonance is crossed repeatedly in a prescribed manner consisting of linear ramping segments or sudden jumps. How repeated crossings produce an interference behavior is discussed using the results obtained. For a polarized beam with finite energy spread, a spin echo experiment is suggested to explore this interference effect.

  1. Computational quantum chemistry for single Heisenberg spin couplings made simple: Just one spin flip required

    SciTech Connect

    Mayhall, Nicholas J.; Head-Gordon, Martin

    2014-10-07

    We highlight a simple strategy for computing the magnetic coupling constants, J, for a complex containing two multiradical centers. On the assumption that the system follows Heisenberg Hamiltonian physics, J is obtained from a spin-flip electronic structure calculation where only a single electron is excited (and spin-flipped), from the single reference with maximum S{sup ^}{sub z}, M, to the M − 1 manifold, regardless of the number of unpaired electrons, 2M, on the radical centers. In an active space picture involving 2M orbitals, only one β electron is required, together with only one α hole. While this observation is extremely simple, the reduction in the number of essential configurations from exponential in M to only linear provides dramatic computational benefits. This (M, M − 1) strategy for evaluating J is an unambiguous, spin-pure, wave function theory counterpart of the various projected broken symmetry density functional theory schemes, and likewise gives explicit energies for each possible spin-state that enable evaluation of properties. The approach is illustrated on five complexes with varying numbers of unpaired electrons, for which one spin-flip calculations are used to compute J. Some implications for further development of spin-flip methods are discussed.

  2. Resonant optical control of the electrically induced spin polarization by periodic excitation

    NASA Astrophysics Data System (ADS)

    Hernandez, F. G. G.; Gusev, G. M.; Bakarov, A. K.

    2014-07-01

    We show that the electron spin polarization generated by an electrical current may have its direction controlled and magnitude amplified by periodic optical excitation. The electrical and optical spin control methods were combined and implemented in a two-dimensional electron gas. By Kerr rotation in an external transverse magnetic field, we demonstrate unexpected long-lived coherent spin oscillations of the current-induced signal in a system with large spin-orbit interaction. Using a single linearly polarized pulse for spin manipulation and detection, we found a strong dependence on the pulse optical power and sample temperature indicating the relevance of the hole spin in the electron spin initialization. The signal was mapped in a Hall bar as function of the position relative to the injection contact. Finally, the presence of an in-plane spin polarization was directly verified by rotating the experimental geometry.

  3. Fast electron spin resonance controlled manipulation of spin injection into quantum dots

    SciTech Connect

    Merz, Andreas Siller, Jan; Schittny, Robert; Krämmer, Christoph; Kalt, Heinz; Hetterich, Michael

    2014-06-23

    In our spin-injection light-emitting diodes, electrons are spin-polarized in a semimagnetic ZnMnSe spin aligner and then injected into InGaAs quantum dots. The resulting electron spin state can be read out by measuring the circular polarization state of the emitted light. Here, we resonantly excite the Mn 3d electron spin system with microwave pulses and perform time-resolved measurements of the spin dynamics. We find that we are able to control the spin polarization of the injected electrons on a microsecond timescale. This electron spin resonance induced spin control could be one of the ingredients required to utilize the quantum dot electrons or the Mn spins as qubits.

  4. Single top quark production at the LHC: Understanding spin

    SciTech Connect

    Jensen, S.

    1999-12-22

    The authors show that the single top quarks produced in the Wg-fusion channel at a proton-proton collider at a center-of-mass energy {radical}s = 14 TeV posses a high degree of polarization in terms of a spin basis which decomposes the top quark spin in its rest frame along the direction of the spectator jet. A second useful spin basis is the {eta}-beamline basis, which decomposes the top quark spin along one of the two beam directions, depending on which hemisphere contains the spectator jet. The authors elucidate the interplay between the two- and three-body final states contributing to this production cross section in the context of determining the spin decomposition of the top quarks, and argue that the zero momentum frame helicity is undefined. The authors show that the usefulness of the spectator and {eta}-beamline spin bases is not adversely affected by the cuts required to separate the Wg-fusion signal from the background.

  5. Nonlinear Single-Spin Spectrum Analyzer

    NASA Astrophysics Data System (ADS)

    Kotler, Shlomi; Akerman, Nitzan; Glickman, Yinnon; Ozeri, Roee

    2013-03-01

    Qubits have been used as linear spectrum analyzers of their environments. Here we solve the problem of nonlinear spectral analysis, required for discrete noise induced by a strongly coupled environment. Our nonperturbative analytical model shows a nonlinear signal dependence on noise power, resulting in a spectral resolution beyond the Fourier limit as well as frequency mixing. We develop a noise characterization scheme adapted to this nonlinearity. We then apply it using a single trapped ion as a sensitive probe of strong, non-Gaussian, discrete magnetic field noise. Finally, we experimentally compared the performance of equidistant vs Uhrig modulation schemes for spectral analysis.

  6. Attitude control of a spinning rocket via thrust vectoring

    SciTech Connect

    White, J.E.

    1990-12-19

    Two controllers are developed to provide attitude control of a spinning rocket that has a thrust vectoring capability. The first controller has a single-input/single-output design that ignores the gyroscopic coupling between the control channels. The second controller has a multi-input/multi-output structure that is specifically intended to account for the gyroscopic coupling effects. A performance comparison between the two approached is conducted for a range of roll rates. Each controller is tested for the ability to track step commands, and for the amount of coupling impurity. Both controllers are developed via a linear-quadratic-regulator synthesis procedure, which is motivated by the multi-input/multi-output nature of second controller. Time responses and a singular value analysis are used to evaluate controller performance. This paper describes the development and comparison of two controllers that are designed to provide attitude control of a spinning rocket that is equipped with thrust vector control. 12 refs., 13 figs., 2 tabs.

  7. Single-proton spin detection by diamond magnetometry.

    PubMed

    Loretz, M; Rosskopf, T; Boss, J M; Pezzagna, S; Meijer, J; Degen, C L

    2014-10-16

    Extending magnetic resonance imaging to the atomic scale has been a long-standing aspiration, driven by the prospect of directly mapping atomic positions in molecules with three-dimensional spatial resolution. We report detection of individual, isolated proton spins by a nitrogen-vacancy (NV) center in a diamond chip covered by an inorganic salt. The single-proton identity was confirmed by the Zeeman effect and by a quantum coherent rotation of the weakly coupled nuclear spin. Using the hyperfine field of the NV center as an imaging gradient, we determined proton-NV distances of less than 1 nm. PMID:25323696

  8. Nanometre-scale probing of spin waves using single-electron spins

    PubMed Central

    van der Sar, Toeno; Casola, Francesco; Walsworth, Ronald; Yacoby, Amir

    2015-01-01

    Pushing the frontiers of condensed-matter magnetism requires the development of tools that provide real-space, few-nanometre-scale probing of correlated-electron magnetic excitations under ambient conditions. Here we present a practical approach to meet this challenge, using magnetometry based on single nitrogen-vacancy centres in diamond. We focus on spin-wave excitations in a ferromagnetic microdisc, and demonstrate local, quantitative and phase-sensitive detection of the spin-wave magnetic field at ∼50 nm from the disc. We map the magnetic-field dependence of spin-wave excitations by detecting the associated local reduction in the disc's longitudinal magnetization. In addition, we characterize the spin–noise spectrum by nitrogen-vacancy spin relaxometry, finding excellent agreement with a general analytical description of the stray fields produced by spin–spin correlations in a 2D magnetic system. These complementary measurement modalities pave the way towards imaging the local excitations of systems such as ferromagnets and antiferromagnets, skyrmions, atomically assembled quantum magnets, and spin ice. PMID:26249673

  9. Electron spin resonance and muon spin relaxation studies of single molecule magnets

    NASA Astrophysics Data System (ADS)

    Blundell, Stephen

    2005-03-01

    We use a combination of electron spin resonance, muon-spin relaxation and SQUID magnetometry to study polycrystalline and single crystal samples of various novel single molecule magnets (SMMs). We also describe a theoretical framework which can be used to analyse the results from each technique. Electron spin resonance measurements are performed using a millimetre vector network analyser and data are presented on several SMM systems using microwave frequencies from 40-300 GHz. Muon-spin relaxation measurements have been performed on several SMM systems in applied longitudinal magnetic field and in temperatures down to 20 mK. The results suggest that dynamic local magnetic field fluctuations are responsible for the relaxation of the muon spin ensemble. We discuss what can be learned from these experiments concerning SMMs and suggest experiments which can probe the quantum nature of SMMs. (Work in collaboration with S Sharmin, T Lancaster, A Ardavan, F L Pratt, E J L McInnes and R E P Winpenny) References: S. J. Blundell and F. L. Pratt, J. Phys.: Condens. Matter 16, R771 (2004); T. Lancaster et al., J. Phys.: Condens. Matter 16, S4563 (2004); S. Sharmin et al., Appl. Phys. Lett. in press.

  10. Entangled absorption of a single photon with a single spin in diamond.

    PubMed

    Kosaka, Hideo; Niikura, Naeko

    2015-02-01

    Quantum entanglement, a key resource for quantum information science, is inherent in a solid. It has been recently shown that entanglement between a single optical photon and a single spin qubit in a solid is generated via spontaneous emission. However, entanglement generation by measurement is rather essential for quantum operations. We here show that the physics behind the entangled emission can be time reversed to demonstrate entangled absorption mediated by an inherent spin-orbit entanglement in a single nitrogen vacancy center in diamond. Optical arbitrary spin state preparation and complete spin state tomography reveal the fidelity of the entangled absorption to be 95%. With the entangled emission and absorption of a photon, materials can be spontaneously entangled or swap their quantum state based on the quantum teleportation scheme. PMID:25699440

  11. Strong spin relaxation anisotropy in a single-electron quantum dot

    NASA Astrophysics Data System (ADS)

    Yu, Liuqi; Camenzind, L. C.; Biesinger, D. E. F.; Zimmerman, J.; Gossard, A. C.; Zumbühl, D. M.

    Spin coherence and relaxation is of crucial importance in operating spin based qubits. In a magnetic field, spins relax predominately through spin-phonon coupling mediated by spin-orbit interaction (SOI). Here we present measurements of the spin relaxation rate anisotropy in a gate defined single-electron GaAs quantum dot. The spin relaxation rate W is measured at applied magnetic fields of 4 T in the plane of the 2D electron gas. W exhibits strong anisotropy: a sinusoidal dependence on the B-field angle φ with a period of 180 degrees, as reported recently. The extrema are observed at fields pointing nearly along the [110] and [1-10] crystal axes, modulated by a factor of about 14 from minimum to maximum. The periodicity is attributed to the interplay of Rashba and Dresselhaus SOIs. To decipher the role of SOI, we perform pulsed-gate spectroscopy to extract orbital excited-state energies, and obtain very good agreement with theory also for the angular dependence W(φ) , indicating that α and β, Rashba and Dresselhaus coefficients respectively, have the same relative sign and are within 20% of each other. With controllable manipulations of the dot orbitals by varying gate voltages, it is possible to precisely extract values of α and β. Meanwhile, top- and back gates have been implemented on the device structure, which allows full electrical control over the Rashba SOI in the 2D electron gas

  12. Electrical control of spin in topological insulators

    NASA Astrophysics Data System (ADS)

    Chang, Kai

    2012-02-01

    All-electrical manipulation of electron spin in solids becomes a central issue of quantum information processing and quantum computing. The many previous proposals are based on spin-orbit interactions in semiconductors. Topological insulator, a strong spin-orbit coupling system, make it possible to control the spin transport electrically. Recent calculations proved that external electric fields can drive a HgTe quantum well from normal band insulator phase to topological insulator phase [1]. Since the topological edge states are robust against local perturbation, the controlling of edge states using local fields is a challenging task. We demonstrate that a p-n junction created electrically in HgTe quantum wells with inverted band structure exhibits interesting intraband and interband tunneling processes. We find a perfect intraband transmission for electrons injected perpendicularly to the interface of the p-n junction. The opacity and transparency of electrons through the p-n junction can be tuned by changing the incidence angle, the Fermi energy and the strength of the Rashba spin-orbit interaction (RSOI). The occurrence of a conductance plateau due to the formation of topological edge states in a quasi-one-dimensional p-n junction can be switched on and off by tuning the gate voltage. The spin orientation can be substantially rotated when the samples exhibit a moderately strong RSOI [2]. An electrical switching of the edge-state transport can also be realized using quantum point contacts in quantum spin Hall bars. The switch-on/off of the edge channel is caused by the finite size effect of the quantum point contact and therefore can be manipulated by tuning the voltage applied on the split gate [3,4]. The magnetic ions doped on the surface of 3D TI can be correlated through the helical electrons. The RKKY interaction mediated by the helical Dirac electrons consists of the Heisenberg-like, Ising-like, and Dzyaloshinskii-Moriya (DM)-like terms, which can be tuned

  13. Probing Spin Accumulation induced Magnetocapacitance in a Single Electron Transistor

    PubMed Central

    Lee, Teik-Hui; Chen, Chii-Dong

    2015-01-01

    The interplay between spin and charge in solids is currently among the most discussed topics in condensed matter physics. Such interplay gives rise to magneto-electric coupling, which in the case of solids was named magneto-electric effect, as predicted by Curie on the basis of symmetry considerations. This effect enables the manipulation of magnetization using electrical field or, conversely, the manipulation of electrical polarization by magnetic field. The latter is known as the magnetocapacitance effect. Here, we show that non-equilibrium spin accumulation can induce tunnel magnetocapacitance through the formation of a tiny charge dipole. This dipole can effectively give rise to an additional serial capacitance, which represents an extra charging energy that the tunneling electrons would encounter. In the sequential tunneling regime, this extra energy can be understood as the energy required for a single spin to flip. A ferromagnetic single-electron-transistor with tunable magnetic configuration is utilized to demonstrate the proposed mechanism. It is found that the extra threshold energy is experienced only by electrons entering the islands, bringing about asymmetry in the measured Coulomb diamond. This asymmetry is an unambiguous evidence of spin accumulation induced tunnel magnetocapacitance, and the measured magnetocapacitance value is as high as 40%. PMID:26348794

  14. Skyrmions and Single Spin-Flips in higher Landau levels

    NASA Astrophysics Data System (ADS)

    Melik-Alaverdian, V.; Bonesteel, N. E.; Ortiz, G.

    1998-03-01

    Skyrmions and single spin-flips in the integer and fractional quantum Hall states are studied numerically in the spherical geometry, including the effects of Landau Level Mixing (LLM) and Finite Thickness (FT). LLM is included by using a generalized Fixed-Phase Diffusion Monte Carlo (FPDMC) technique,(V. Melik-Alaverdian et al., Phys. Rev. Lett. 79) xxx (1997). and FT is included by modifying the short range part of the Coulomb potential. For trial phases in the FPDMC simulation of skyrmions we use the phases of hard-core skyrmion wave functions.(A.H. MacDonald et al., Phys. Rev. Lett. 76) 2153 (1996). We find that both, LLM and FT favor quasiparticles with reduced spins. For the ν=1 state our results for the crossover fields between quasiparticles with different spin polarization are consistent with experiment.(A. Schmeller et al., Phys. Rev. Lett. 75) 4290 (1995). For the ν=1/3 state we predict the range of fields when the skyrmions and single spin-flips become stable. Supported by DOE grant DE-FG0297ER45639. NEB acknowledges the support of an A.P. Sloan Fellowship.

  15. Electron spin resonance spectroscopy of small ensemble paramagnetic spins using a single nitrogen-vacancy center in diamond

    NASA Astrophysics Data System (ADS)

    Abeywardana, Chathuranga; Stepanov, Viktor; Cho, Franklin H.; Takahashi, Susumu

    2016-09-01

    A nitrogen-vacancy (NV) center in diamond is a promising sensor for nanoscale magnetic sensing. Here, we report on electron spin resonance (ESR) spectroscopy using a single NV center in diamond. First, using a 230 GHz ESR spectrometer, we performed ensemble ESR of a type-Ib sample crystal and identified a substitutional single nitrogen impurity as a major paramagnetic center in the sample crystal. Then, we carried out free-induction decay and spin echo measurements of the single NV center to study static and dynamic properties of nanoscale bath spins surrounding the NV center. We also measured ESR spectrum of the bath spins using double electron-electron resonance spectroscopy with the single NV center. The spectrum analysis of the NV-based ESR measurement identified that the detected spins are the nitrogen impurity spins. The experiment was also performed with several other single NV centers in the diamond sample and demonstrated that the properties of the bath spins are unique to the NV centers indicating the probe of spins in the microscopic volume using NV-based ESR. Finally, we discussed the number of spins detected by the NV-based ESR spectroscopy. By comparing the experimental result with simulation, we estimated the number of the detected spins to be ≤50 spins.

  16. Controlling spin-dependent localization and directed transport in a bipartite lattice

    NASA Astrophysics Data System (ADS)

    Luo, Yunrong; Lu, Gengbiao; Kong, Chao; Hai, Wenhua

    2016-04-01

    We study coherent control of spin-dependent dynamical localization (DL) and directed transport (DT) of a spin-orbit-coupled single atom held in a driven optical bipartite lattice. Under the high-frequency limit and nearest-neighbor tight-binding approximation, we find a new decoupling mechanism between states with the same (different) spins, which leads to two sets of analytical solutions describing DL and DT with (without) spin flipping. The analytical results are numerically confirmed, and perfect agreements are found. Extending the research to a system of spin-orbit-coupled single atoms, the spin current and quantum information transport with controllable propagation speed and distance are investigated. The results can be experimentally tested in the current setups and may be useful in quantum information processing.

  17. Time-dependent spin and transport properties of a single-molecule magnet in a tunnel junction

    NASA Astrophysics Data System (ADS)

    Hammar, H.; Fransson, J.

    2016-08-01

    In single-molecule magnets, the exchange between a localized spin moment and the electronic background provides a suitable laboratory for studies of dynamical aspects of both local spin and transport properties. Here we address the time evolution of a localized spin moment coupled to an electronic level in a molecular quantum dot embedded in a tunnel junction between metallic leads. The interactions between the localized spin moment and the electronic level generate an effective interaction between the spin moment at different instances in time. Therefore, we show that, despite being a single-spin system, there are effective contributions of isotropic Heisenberg and anisotropic Ising and Dzyaloshinski-Moriya character acting on the spin moment. The interactions can be controlled by gate voltage, voltage bias, the spin polarization in the leads, in addition to external magnetic fields. Signatures of the spin dynamics are found in the transport properties of the tunneling system, and we demonstrate that measurements of the spin current may be used for readout of the local spin moment orientation.

  18. High fidelity readout of a single electron spin

    NASA Astrophysics Data System (ADS)

    Keselman, Anna; Glickman, Yinnon; Akerman, Nitzan; Kotler, Shlomi; Dallal, Yehonatan; Ozeri, Roee

    2010-03-01

    We use the two spin states of the valence electron of a single trapped ^88Sr^+ ion as a physical qubit implementation. For qubit readout one of the qubit states is shelved to a metastable D level using a narrow linewidth 674nm diode laser followed by state-selective fluorescence detection. Careful analysis of the resulting photon detection statistics allows for a minimal detection error of 2 . 10-3, compatible with recent estimates of the fault-tolerance required error threshold.

  19. Gate-tuned spin to charge conversion in semiconducting single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Shigematsu, Ei; Nagano, Hiroshi; Dushenko, Sergey; Ando, Yuichiro; Tsuda, Tetsuya; Kuwabata, Susumu; Takenobu, Taishi; Tanaka, Takeshi; Kataura, Hiromichi; Shinjo, Teruya; Shiraishi, Masashi

    Interconversion of spin and charge current is a hot topic in the molecular spintronics. It was achieved for the first time in a conducting conjugated polymer 1, and shortly followed by spin-charge conversion in graphene. However, control over carrier type has not been shown yet. In this study we focused on single-walled carbon nanotubes (SWNT). Spin injection into semiconductor from metal ferromagnet is challenging due to the presence of Schottky barrier and conductance mismatch problem. To bypass it, we used ionic liquid electric gate and ferrimagnetic insulator. We prepared SWNT layer on top of ferrimagnetic yttrium iron garnet substrate. Using spin pumping we successfully observed spin-charge conversion in metallic SWNT. As for a semiconducting SWNT, we applied a top gate using ionic liquid. The drain-source current vs. gate voltage dependence showed tuning of the Fermi level and changing of carrier type. Under gate voltage application we measured electromotive force induced by spin pumping. Detected voltage changed its sign together with carrier type. This is first evidence of spin-charge conversion in carbon nanotubes 2. 1 K. Ando et al., Nature Mater. 12, 622 (2013). 2 E. Shigematsu et al., submitted.

  20. Controlling spin polarization in graphene by cloaking magnetic and spin-orbit scatterers

    NASA Astrophysics Data System (ADS)

    Oliver, Diego; Rappoport, Tatiana G.

    2016-07-01

    We consider spin-dependent scatterers with large scattering cross sections in graphene—a Zeeman-like and an intrinsic spin-orbit coupling impurity—and show that a gated ring around them can be engineered to produce an efficient control of the spin-dependent transport, like current spin polarization and spin Hall angle. Our analysis is based on a spin-dependent partial-waves expansion of the electronic wave functions in the continuum approximation, described by the Dirac equation.

  1. Control in Highly Focused Top-Spinning. Brief Report.

    ERIC Educational Resources Information Center

    Berkson, Gershon

    1998-01-01

    Three studies analyzed stimulus feedback and the concept of control with three children and two adults having autism. The first study explored feedback from spinning tops, while the second and third emphasized control of various stimuli including spinning tops. Results indicate that autistic individuals' common interest in spinning tops is…

  2. Coherent Population Trapping of a Single Nuclear Spin Under Ambient Conditions.

    PubMed

    Jamonneau, P; Hétet, G; Dréau, A; Roch, J-F; Jacques, V

    2016-01-29

    We demonstrate coherent population trapping of a single nuclear spin in a room-temperature solid. To this end, we exploit a three-level system with a Λ configuration in the microwave domain, which consists of nuclear spin states addressed through their hyperfine coupling to the electron spin of a single nitrogen-vacancy defect in diamond. Moreover, the Λ-scheme relaxation is externally controlled through incoherent optical pumping and separated in time from consecutive coherent microwave excitations. Such a scheme allows us (i) to monitor the sequential accumulation of population into the dark state and (ii) to reach a novel regime of coherent population trapping dynamics for which periodic arrays of dark resonances can be observed, owing to multiple constructive interferences. This Letter offers new prospects for quantum state preparation, information storage in hybrid quantum systems, and metrology. PMID:26871331

  3. Control of Single Wheel Robots

    NASA Astrophysics Data System (ADS)

    Xu, Yangsheng; Ou, Yongsheng

    This monograph presents a novel concept of a mobile robot, which is a single-wheel, gyroscopically stabilized robot. The robot is balanced by a spinning wheel attached through a two-link manipulator at the wheel bearing, and actuated by a drive motor. This configuration conveys significant advantages including insensitivity to attitude disturbances, high maneuverability, low rolling resistance, ability to recover from falls, and amphibious capability for potential applications on both land and water.

  4. Single transverse spin asymmetry of prompt photon production

    NASA Astrophysics Data System (ADS)

    Gamberg, Leonard; Kang, Zhong-Bo

    2012-11-01

    We study the single transverse spin asymmetry of prompt photon production in high energy proton-proton scattering. We include the contributions from both the direct and fragmentation photons. While the asymmetry for direct photon production receives only the Sivers type of contribution, the asymmetry for fragmentation photons receives both the Sivers and Collins types of contributions. We make a model calculation for quark-to-photon Collins function, which is then used to estimate the Collins asymmetry for fragmentation photons. We find that the Collins asymmetry for fragmentation photons is very small, thus the single transverse spin asymmetry of prompt photon production is mainly coming from the Sivers asymmetry in direct and fragmentation photons. We make predictions for the prompt photon spin asymmetry at RHIC energy, and emphasize the importance of such a measurement. The asymmetry of prompt photon production can provide a good measurement for the important twist-three quark-gluon correlation function, which is urgently needed in order to resolve the "sign mismatch" puzzle.

  5. Observation of a single spin by transferring its coherence to a high level macroscopic pure state

    SciTech Connect

    Kawamura, Minaru

    2014-12-04

    We discuss about quantum measurement of a single spin in a superconducting RF resonator, where amplification of coherence of the spin is enabled by transferring its coherence to the harmonic oscillator in an non-coherent state with high energy level. This quantum amplification allows that a single spin can induce macroscopic current to permits observation of a single spin state in the number and phase uncertainty relation.

  6. Nanomechanical single-qubit gates and iSWAP gate of single-electron spins in a carbon nanotube

    NASA Astrophysics Data System (ADS)

    Wang, Heng; Burkard, Guido

    2015-03-01

    A universal gate set for quantum computation can be built with one-qubit and iSWAP gates. We theoretically investigate mechanically-induced single-electron spin resonance in a quantum dot and a phonon mediated iSWAP gate of two separate single electron spins in two quantum dots on a suspended carbon nanotube which is driven by an external electric field. The intrinsic spin-phonon coupling between the spin and the mechanical mode is induced by the spin-orbit coupling. Arbitrary-angle rotations about arbitrary axes of the single electron spin can be achieved by varying the frequency and the strength of the external electric driving field. If two single-electron spins in two quantum dots couple to the same vibrational mode simultaneously, the two spins are indirectly coupled via phonon exchange. Both electron spin resonance and the iSWAP gate can be turned off by suppressing the spin-phonon coupling by electrostatically shifting the electron wave function on the nanotube. Combining iSWAP and single spin gates, maximally entangled states of two spins can be generated in a single step.

  7. Coherent control over diamond nitrogen-vacancy center spins with a mechanical resonator

    NASA Astrophysics Data System (ADS)

    Fuchs, Gregory

    2015-03-01

    We demonstrate coherent Rabi oscillations of diamond nitrogen-vacancy (NV) center spins driven directly by a mechanical resonator without mediation by a magnetic driving field. Using a bulk-mode acoustic resonator fabricated from single crystal diamond, we exert non-axial ac stress on NV centers positioned at an antinode of a gigahertz frequency mechanical mode. When the Δms = -1 to +1 spin state splitting energy is tuned into resonance with a driven mechanical mode, we observe Δms = +/-2 spin transitions, which are forbidden by the magnetic dipole selection rule. To rule out stray electric and magnetic fields as the origin of these spin transitions, we study the spin signal as a function depth within the diamond resonator. We find that the spin signal reproduces the periodicity of the acoustic standing wave, confirming the mechanical origin of the observed spin resonance. Using single-crystal diamond mechanical resonators with fQ products of 2 ×1012 , we observe coherent mechanically driven Rabi oscillations up to 4 MHz. For ensembles of NV centers coupled to the resonator, we analyze Rabi oscillations and their dephasing with a combination of spatially inhomogeneous mechanical driving and fluctuating magnetic fields from a noisy spin environment. Additionally, we examine the coherence of mechanically controlled NV center qubits and compare it to the coherence of magnetically controlled spin qubits in the NV center ground state spin manifold. This work demonstrates direct and coherent coupling between NV center spins and resonator phonons, which has potential for NV-based metrology using hybrid spin-mechanical sensors, fundamental research into spin-phonon interactions at the nanoscale, and as a platform for hybrid spin-mechanical quantum systems. Funding from ONR is gratefully acknowledged. In collaboration with E. R. MacQuarrie, T. A. Gosavi, A. M. Moehle, N. R. Jungwirth, and S. A. Bhave.

  8. Controlling spin-spin network dynamics by repeated projective measurements

    PubMed Central

    Bretschneider, Christian O.; Álvarez, Gonzalo A.; Kurizki, Gershon; Frydman, Lucio

    2016-01-01

    We show that coupled-spin network manipulations can be made highly effective by repeated “projections” of the evolving quantum states onto diagonal density-matrix states (populations). As opposed to the intricately crafted pulse trains that are often used to fine-tune a complex network’s evolution, the strategy hereby presented derives from the “quantum-Zeno effect” and provides a highly robust route to guide the evolution by destroying all unwanted correlations (coherences). We exploit these effects by showing that a relaxation-like behaviour is endowed to polarization transfers occurring within a N-spin coupled network. Experimental implementations yield coupling constant determinations for complex spin-coupling topologies, as demonstrated within the field of liquid-state nuclear magnetic resonance (NMR). PMID:22540774

  9. Nuclear-driven electron spin rotations in a coupled silicon quantum dot and single donor system

    NASA Astrophysics Data System (ADS)

    Harvey-Collard, Patrick; Jacobson, Noah Tobias; Rudolph, Martin; Ten Eyck, Gregory A.; Wendt, Joel R.; Pluym, Tammy; Lilly, Michael P.; Pioro-Ladrière, Michel; Carroll, Malcolm S.

    Single donors in silicon are very good qubits. However, a central challenge is to couple them to one another. To achieve this, many proposals rely on using a nearby quantum dot (QD) to mediate an interaction. In this work, we demonstrate the coherent coupling of electron spins between a single 31P donor and an enriched 28Si metal-oxide-semiconductor few-electron QD. We show that the electron-nuclear spin interaction can drive coherent rotations between singlet and triplet electron spin states. Moreover, we are able to tune electrically the exchange interaction between the QD and donor electrons. The combination of single-nucleus-driven rotations and voltage-tunable exchange provides all elements for future all-electrical control of a spin qubit, and requires only a single dot and no additional magnetic field gradients. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  10. Dynamic strain-mediated coupling of a single diamond spin to a mechanical resonator

    PubMed Central

    Ovartchaiyapong, Preeti; Lee, Kenneth W.; Myers, Bryan A.; Jayich, Ania C. Bleszynski

    2014-01-01

    The development of hybrid quantum systems is central to the advancement of emerging quantum technologies, including quantum information science and quantum-assisted sensing. The recent demonstration of high-quality single-crystal diamond resonators has led to significant interest in a hybrid system consisting of nitrogen–vacancy centre spins that interact with the resonant phonon modes of a macroscopic mechanical resonator through crystal strain. However, the nitrogen–vacancy spin–strain interaction has not been well characterized. Here, we demonstrate dynamic, strain-mediated coupling of the mechanical motion of a diamond cantilever to the spin of an embedded nitrogen–vacancy centre. Via quantum control of the spin, we quantitatively characterize the axial and transverse strain sensitivities of the nitrogen–vacancy ground-state spin. The nitrogen–vacancy centre is an atomic scale sensor and we demonstrate spin-based strain imaging with a strain sensitivity of 3 × 10−6 strain Hz−1/2. Finally, we show how this spin-resonator system could enable coherent spin–phonon interactions in the quantum regime. PMID:25034828

  11. Controlling Thermal Entanglement in a Three-qubit Spin System

    NASA Astrophysics Data System (ADS)

    Li, Jianping

    2016-09-01

    In this paper, thermal entanglement in three-qubit spin system has been addressed. The results show that spin-spin exchange interaction, the effective external magnetic field, next-nearest-neighbouring interaction have notable effects on the time evolution of the state and thermal entanglement So we can control thermal entanglement by changing the above parameters.

  12. Continuous control of spin polarization using a magnetic field

    NASA Astrophysics Data System (ADS)

    Gifford, J. A.; Zhao, G. J.; Li, B. C.; Tracy, Brian D.; Zhang, J.; Kim, D. R.; Smith, David J.; Chen, T. Y.

    2016-05-01

    The giant magnetoresistance (GMR) of a point contact between a Co/Cu multilayer and a superconductor tip varies for different bias voltage. Direct measurement of spin polarization by Andreev reflection spectroscopy reveals that the GMR change is due to a change in spin polarization. This work demonstrates that the GMR structure can be utilized as a spin source and that the spin polarization can be continuously controlled by using an external magnetic field.

  13. Single-spin magnetometry with multipulse sensing sequences.

    PubMed

    de Lange, G; Ristè, D; Dobrovitski, V V; Hanson, R

    2011-02-25

    We experimentally demonstrate single-spin magnetometry with multipulse sensing sequences. The use of multipulse sequences can greatly increase the sensing time per measurement shot, resulting in enhanced ac magnetic field sensitivity. We theoretically derive and experimentally verify the optimal number of sensing cycles, for which the effects of decoherence and increased sensing time are balanced. We perform these experiments for oscillating magnetic fields with fixed phase as well as for fields with random phase. Finally, by varying the phase and frequency of the ac magnetic field, we measure the full frequency-filtering characteristics of different multipulse schemes and discuss their use in magnetometry applications.

  14. Half-metallic properties, single-spin negative differential resistance, and large single-spin Seebeck effects induced by chemical doping in zigzag-edged graphene nanoribbons

    SciTech Connect

    Yang, Xi-Feng; Zhou, Wen-Qian; Hong, Xue-Kun; Liu, Yu-Shen Feng, Jin-Fu; Wang, Xue-Feng

    2015-01-14

    Ab initio calculations combining density-functional theory and nonequilibrium Green’s function are performed to investigate the effects of either single B atom or single N atom dopant in zigzag-edged graphene nanoribbons (ZGNRs) with the ferromagnetic state on the spin-dependent transport properties and thermospin performances. A spin-up (spin-down) localized state near the Fermi level can be induced by these dopants, resulting in a half-metallic property with 100% negative (positive) spin polarization at the Fermi level due to the destructive quantum interference effects. In addition, the highly spin-polarized electric current in the low bias-voltage regime and single-spin negative differential resistance in the high bias-voltage regime are also observed in these doped ZGNRs. Moreover, the large spin-up (spin-down) Seebeck coefficient and the very weak spin-down (spin-up) Seebeck effect of the B(N)-doped ZGNRs near the Fermi level are simultaneously achieved, indicating that the spin Seebeck effect is comparable to the corresponding charge Seebeck effect.

  15. Angstrom-Resolution Magnetic Resonance Imaging of Single Molecules via Wave-Function Fingerprints of Nuclear Spins

    NASA Astrophysics Data System (ADS)

    Ma, Wen-Long; Liu, Ren-Bao

    2016-08-01

    Single-molecule sensitivity of nuclear magnetic resonance (NMR) and angstrom resolution of magnetic resonance imaging (MRI) are the highest challenges in magnetic microscopy. Recent development in dynamical-decoupling- (DD) enhanced diamond quantum sensing has enabled single-nucleus NMR and nanoscale NMR. Similar to conventional NMR and MRI, current DD-based quantum sensing utilizes the "frequency fingerprints" of target nuclear spins. The frequency fingerprints by their nature cannot resolve different nuclear spins that have the same noise frequency or differentiate different types of correlations in nuclear-spin clusters, which limit the resolution of single-molecule MRI. Here we show that this limitation can be overcome by using "wave-function fingerprints" of target nuclear spins, which is much more sensitive than the frequency fingerprints to the weak hyperfine interaction between the targets and a sensor under resonant DD control. We demonstrate a scheme of angstrom-resolution MRI that is capable of counting and individually localizing single nuclear spins of the same frequency and characterizing the correlations in nuclear-spin clusters. A nitrogen-vacancy-center spin sensor near a diamond surface, provided that the coherence time is improved by surface engineering in the near future, may be employed to determine with angstrom resolution the positions and conformation of single molecules that are isotope labeled. The scheme in this work offers an approach to breaking the resolution limit set by the "frequency gradients" in conventional MRI and to reaching the angstrom-scale resolution.

  16. Multi-dimensional single-spin nano-optomechanics with a levitated nanodiamond

    NASA Astrophysics Data System (ADS)

    Neukirch, Levi P.; von Haartman, Eva; Rosenholm, Jessica M.; Nick Vamivakas, A.

    2015-10-01

    Considerable advances made in the development of nanomechanical and nano-optomechanical devices have enabled the observation of quantum effects, improved sensitivity to minute forces, and provided avenues to probe fundamental physics at the nanoscale. Concurrently, solid-state quantum emitters with optically accessible spin degrees of freedom have been pursued in applications ranging from quantum information science to nanoscale sensing. Here, we demonstrate a hybrid nano-optomechanical system composed of a nanodiamond (containing a single nitrogen-vacancy centre) that is levitated in an optical dipole trap. The mechanical state of the diamond is controlled by modulation of the optical trapping potential. We demonstrate the ability to imprint the multi-dimensional mechanical motion of the cavity-free mechanical oscillator into the nitrogen-vacancy centre fluorescence and manipulate the mechanical system's intrinsic spin. This result represents the first step towards a hybrid quantum system based on levitating nanoparticles that simultaneously engages optical, phononic and spin degrees of freedom.

  17. Spin-flip configuration interaction singles with exact spin-projection: Theory and applications to strongly correlated systems

    SciTech Connect

    Tsuchimochi, Takashi

    2015-10-14

    Spin-flip approaches capture static correlation with the same computational scaling as the ordinary single reference methods. Here, we extend spin-flip configuration interaction singles (SFCIS) by projecting out intrinsic spin-contamination to make it spin-complete, rather than by explicitly complementing it with spin-coupled configurations. We give a general formalism of spin-projection for SFCIS, applicable to any spin states. The proposed method is viewed as a natural unification of SFCIS and spin-projected CIS to achieve a better qualitative accuracy at a low computational cost. While our wave function ansatz is more compact than previously proposed spin-complete SF approaches, it successfully offers more general static correlation beyond biradicals without sacrificing good quantum numbers. It is also shown that our method is invariant with respect to open-shell orbital rotations, due to the uniqueness of spin-projection. We will report benchmark calculations to demonstrate its qualitative performance on strongly correlated systems, including conical intersections that appear both in ground-excited and excited-excited degeneracies.

  18. Observation of spin-charge conversion in chemical-vapor-deposition-grown single-layer graphene

    SciTech Connect

    Ohshima, Ryo; Sakai, Atsushi; Ando, Yuichiro; Shiraishi, Masashi; Shinjo, Teruya; Kawahara, Kenji; Ago, Hiroki

    2014-10-20

    Conversion of pure spin current to charge current in single-layer graphene (SLG) is investigated by using spin pumping. Large-area SLG grown by chemical vapor deposition is used for the conversion. Efficient spin accumulation in SLG by spin pumping enables observing an electromotive force produced by the inverse spin Hall effect (ISHE) of SLG. The spin Hall angle of SLG is estimated to be 6.1 × 10{sup −7}. The observed ISHE in SLG is ascribed to its non-negligible spin-orbit interaction in SLG.

  19. Completely independent electrical control of spin and valley in a silicene field effect transistor.

    PubMed

    Zhai, Xuechao; Jin, Guojun

    2016-09-01

    One-atom-thick silicene is a silicon-based hexagonal-lattice material with buckled structure, where an electron fuses multiple degrees of freedom including spin, sublattice pseudospin and valley. We here demonstrate that a valley-selective spin filter (VSSF) that supports single-valley and single-spin transport can be realized in a silicene field effect transistor constructed of an npn junction, where an antiferromagnetic exchange field and a perpendicular electric field are applied in the p-doped region. The nontrivial VSSF property benefits from an electrically controllable state of spin-polarized single-valley Dirac cone. By reversing the electric field direction, the device can operate as a spin-reversed but valley-unreversed filter due to the dependence of band gap on spin and valley. Further, we find that all the possible spin-valley configurations of VSSF can be achieved just by tuning the electric field. Our findings pave the way to the realization of completely independent electrical control of spin and valley in silicene circuits. PMID:27385325

  20. Completely independent electrical control of spin and valley in a silicene field effect transistor

    NASA Astrophysics Data System (ADS)

    Zhai, Xuechao; Jin, Guojun

    2016-09-01

    One-atom-thick silicene is a silicon-based hexagonal-lattice material with buckled structure, where an electron fuses multiple degrees of freedom including spin, sublattice pseudospin and valley. We here demonstrate that a valley-selective spin filter (VSSF) that supports single-valley and single-spin transport can be realized in a silicene field effect transistor constructed of an npn junction, where an antiferromagnetic exchange field and a perpendicular electric field are applied in the p-doped region. The nontrivial VSSF property benefits from an electrically controllable state of spin-polarized single-valley Dirac cone. By reversing the electric field direction, the device can operate as a spin-reversed but valley-unreversed filter due to the dependence of band gap on spin and valley. Further, we find that all the possible spin-valley configurations of VSSF can be achieved just by tuning the electric field. Our findings pave the way to the realization of completely independent electrical control of spin and valley in silicene circuits.

  1. Completely independent electrical control of spin and valley in a silicene field effect transistor.

    PubMed

    Zhai, Xuechao; Jin, Guojun

    2016-09-01

    One-atom-thick silicene is a silicon-based hexagonal-lattice material with buckled structure, where an electron fuses multiple degrees of freedom including spin, sublattice pseudospin and valley. We here demonstrate that a valley-selective spin filter (VSSF) that supports single-valley and single-spin transport can be realized in a silicene field effect transistor constructed of an npn junction, where an antiferromagnetic exchange field and a perpendicular electric field are applied in the p-doped region. The nontrivial VSSF property benefits from an electrically controllable state of spin-polarized single-valley Dirac cone. By reversing the electric field direction, the device can operate as a spin-reversed but valley-unreversed filter due to the dependence of band gap on spin and valley. Further, we find that all the possible spin-valley configurations of VSSF can be achieved just by tuning the electric field. Our findings pave the way to the realization of completely independent electrical control of spin and valley in silicene circuits.

  2. Rotary balance data for a typical single-engine general aviation design for an angle-of-attack range of 20 to 90 deg. 3: Influence of control deflection on predicted model D spin modes

    NASA Technical Reports Server (NTRS)

    Ralston, J. N.; Barnhart, B. P.

    1984-01-01

    The influence of control deflections on the rotational flow aerodynamics and on predicted spin modes is discussed for a 1/6-scale general aviation airplane model. The model was tested for various control settings at both zero and ten degree sideslip angles. Data were measured, using a rotary balance, over an angle-of-attack range of 30 deg to 90 deg, and for clockwise and counter-clockwise rotations covering an omegab/2V range of 0 to 0.5.

  3. Decoherence imaging of spin ensembles using a scanning single-electron spin in diamond

    PubMed Central

    Luan, Lan; Grinolds, Michael S.; Hong, Sungkun; Maletinsky, Patrick; Walsworth, Ronald L.; Yacoby, Amir

    2015-01-01

    The nitrogen-vacancy (NV) defect center in diamond has demonstrated great capability for nanoscale magnetic sensing and imaging for both static and periodically modulated target fields. However, it remains a challenge to detect and image randomly fluctuating magnetic fields. Recent theoretical and numerical works have outlined detection schemes that exploit changes in decoherence of the detector spin as a sensitive measure for fluctuating fields. Here we experimentally monitor the decoherence of a scanning NV center in order to image the fluctuating magnetic fields from paramagnetic impurities on an underlying diamond surface. We detect a signal corresponding to roughly 800 μB in 2 s of integration time, without any control on the target spins, and obtain magnetic-field spectral information using dynamical decoupling techniques. The extracted spatial and temporal properties of the surface paramagnetic impurities provide insight to prolonging the coherence of near-surface qubits for quantum information and metrology applications. PMID:25631646

  4. Electric field controlled spin interference in a system with Rashba spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Ciftja, Orion

    2016-05-01

    There have been intense research efforts over the last years focused on understanding the Rashba spin-orbit coupling effect from the perspective of possible spintronics applications. An important component of this line of research is aimed at control and manipulation of electron's spin degrees of freedom in semiconductor quantum dot devices. A promising way to achieve this goal is to make use of the tunable Rashba effect that relies on the spin-orbit interaction in a two-dimensional electron system embedded in a host semiconducting material that lacks inversion-symmetry. This way, the Rashba spin-orbit coupling effect may potentially lead to fabrication of a new generation of spintronic devices where control of spin, thus magnetic properties, is achieved via an electric field and not a magnetic field. In this work we investigate theoretically the electron's spin interference and accumulation process in a Rashba spin-orbit coupled system consisting of a pair of two-dimensional semiconductor quantum dots connected to each other via two conducting semi-circular channels. The strength of the confinement energy on the quantum dots is tuned by gate potentials that allow "leakage" of electrons from one dot to another. While going through the conducting channels, the electrons are spin-orbit coupled to a microscopically generated electric field applied perpendicular to the two-dimensional system. We show that interference of spin wave functions of electrons travelling through the two channels gives rise to interference/conductance patterns that lead to the observation of the geometric Berry's phase. Achieving a predictable and measurable observation of Berry's phase allows one to control the spin dynamics of the electrons. It is demonstrated that this system allows use of a microscopically generated electric field to control Berry's phase, thus, enables one to tune the spin-dependent interference pattern and spintronic properties with no need for injection of spin

  5. Spin-dependent thermoelectronic transport of a single molecule magnet Mn(dmit){sub 2}

    SciTech Connect

    Su, Zhongbo; Wei, Xinyuan; Yang, Zhongqin; An, Yipeng

    2014-05-28

    We investigate spin-dependent thermoelectronic transport properties of a single molecule magnet Mn(dmit){sub 2} sandwiched between two Au electrodes using first-principles density functional theory combined with nonequilibrium Green's function method. By applying a temperature difference between the two Au electrodes, spin-up and spin-down currents flowing in opposite directions can be induced due to asymmetric distribution of the spin-up and spin-down transmission spectra around the Fermi level. A pure spin current and 100% spin polarization are achieved by tuning back-gate voltage to the system. The spin caloritronics of the molecule with a perpendicular conformation is also explored, where the spin-down current is blocked strongly. These results suggest that Mn(dmit){sub 2} is a promising material for spin caloritronic applications.

  6. Single-spin manipulation by electric fields and adsorption of molecules

    NASA Astrophysics Data System (ADS)

    Tao, Kun; Xue, Desheng; Polyakov, O. P.; Stepanyuk, V. S.

    2016-07-01

    Performing ab initio calculations, we reveal that the magnetic anisotropy (MA) and the spin direction of a single adatom can be manipulated with a combination of electric fields and adsorption of molecules. Choosing the Fe adatom on the Cu2N /Cu (001 ) surface as a typical model system, we show that the MA of the pristine Fe adatom and the Fe adatom with an additional H or F atom adsorption remarkably changes by applying an external electric field. Moreover, we show that the F adsorption leads to the spin-reorientation transition of the Fe adatom from in plane to out of plane. Controlling the magnetization dynamics of a single magnetic adatom by molecule adsorption is demonstrated.

  7. Controllable spin polarization and spin filtering in a zigzag silicene nanoribbon

    SciTech Connect

    Farokhnezhad, Mohsen Esmaeilzadeh, Mahdi Pournaghavi, Nezhat; Ahmadi, Somaieh

    2015-05-07

    Using non-equilibrium Green's function, we study the spin-dependent electron transport properties in a zigzag silicene nanoribbon. To produce and control spin polarization, it is assumed that two ferromagnetic strips are deposited on the both edges of the silicene nanoribbon and an electric field is perpendicularly applied to the nanoribbon plane. The spin polarization is studied for both parallel and anti-parallel configurations of exchange magnetic fields induced by the ferromagnetic strips. We find that complete spin polarization can take place in the presence of perpendicular electric field for anti-parallel configuration and the nanoribbon can work as a perfect spin filter. The spin direction of transmitted electrons can be easily changed from up to down and vice versa by reversing the electric field direction. For parallel configuration, perfect spin filtering can occur even in the absence of electric field. In this case, the spin direction can be changed by changing the electron energy. Finally, we investigate the effects of nonmagnetic Anderson disorder on spin dependent conductance and find that the perfect spin filtering properties of nanoribbon are destroyed by strong disorder, but the nanoribbon retains these properties in the presence of weak disorder.

  8. Single-spin precessing gravitational waveform in closed form

    NASA Astrophysics Data System (ADS)

    Lundgren, Andrew; O'Shaughnessy, R.

    2014-02-01

    In coming years, gravitational-wave detectors should find black hole-neutron star (BH-NS) binaries, potentially coincident with astronomical phenomena like short gamma ray bursts. These binaries are expected to precess. Gravitational-wave science requires a tractable model for precessing binaries, to disentangle precession physics from other phenomena like modified strong field gravity, tidal deformability, or Hubble flow; and to measure compact object masses, spins, and alignments. Moreover, current searches for gravitational waves from compact binaries use templates where the binary does not precess and are ill-suited for detection of generic precessing sources. In this paper we provide a closed-form representation of the single-spin precessing waveform in the frequency domain by reorganizing the signal as a sum over harmonics, each of which resembles a nonprecessing waveform. This form enables simple analytic calculations of the Fisher matrix for use in template bank generation and coincidence metrics, and jump proposals to improve the efficiency of Markov chain Monte Carlo sampling. We have verified that for generic BH-NS binaries, our model agrees with the time-domain waveform to 2%. Straightforward extensions of the derivations outlined here (and provided in full online) allow higher accuracy and error estimates.

  9. Electric control of spin in monolayer WSe₂ field effect transistors.

    PubMed

    Gong, Kui; Zhang, Lei; Liu, Dongping; Liu, Lei; Zhu, Yu; Zhao, Yonghong; Guo, Hong

    2014-10-31

    We report first-principles theoretical investigations of quantum transport in a monolayer WSe2 field effect transistor (FET). Due to strong spin-orbit interaction (SOI) and the atomic structure of the two-dimensional lattice, monolayer WSe2 has an electronic structure that exhibits Zeeman-like up-down spin texture near the K and K' points of the Brillouin zone. In a FET, the gate electric field induces an extra, externally tunable SOI that re-orients the spins into a Rashba-like texture thereby realizing electric control of the spin. The conductance of FET is modulated by the spin texture, namely by if the spin orientation of the carrier after the gated channel region, matches or miss-matches that of the FET drain electrode. The carrier current I(τ, s) in the FET is labelled by both the valley index and spin index, realizing valleytronics and spintronics in the same device. PMID:25287881

  10. Information transmission and control in a chaotically kicked spin chain

    NASA Astrophysics Data System (ADS)

    Aubourg, Lucile; Viennot, David

    2016-06-01

    We study spin chains submitted to disturbed kick trains described by classical dynamical processes. The spin chains are coupled by Heisenberg and Ising-Z models. We consider chaotic processes by using the kick irregularity in the multipartite system (the spin chain). We show that both couplings transmit the chaos disorder differently along the spin chain but conserve the horizon of coherence (when the disorder into the kick bath is transmitted to the spin chain). An example of information transmission between the spins of the chain coupled by a Heisenberg interaction shows the interest of the horizon of coherence. The use of some chosen stationary kicks disturbed by a chaotic environment makes it possible to modify the information transmission between the spins and to perform a free control during the horizon of coherence.

  11. Calculation of TMD Evolution for Transverse Single Spin Asymmetry Measurements

    SciTech Connect

    Mert Aybat, Ted Rogers, Alexey Prokudin

    2012-06-01

    In this letter, we show that it is necessary to include the full treatment of QCD evolution of Transverse Momentum Dependent parton densities to explain discrepancies between HERMES data and recent COMPASS data on a proton target for the Sivers transverse single spin asymmetry in Semi-Inclusive Deep Inelastic Scattering (SIDIS). Calculations based on existing fits to TMDs in SIDIS, and including evolution within the Collins-Soper-Sterman with properly defined TMD PDFs are shown to provide a good explanation for the discrepancy. The non-perturbative input needed for the implementation of evolution is taken from earlier analyses of unpolarized Drell-Yan (DY) scattering at high energy. Its success in describing the Sivers function in SIDIS data at much lower energies is strong evidence in support of the unifying aspect of the QCD TMD-factorization formalism.

  12. Scanning SQUID microscopy with single electron spin sensitivity

    NASA Astrophysics Data System (ADS)

    Vasyukov, Denis

    2014-03-01

    Superconducting interference devices (SQUIDs) have been traditionally used for studying fundamental properties of magnetic materials and superconductors. Although widely used in scanning magnetic microscopy, their progress towards detection of small magnetic moments was stagnating of late due to limitations imposed by conventional designs of planar SQUIDs and contemporary lithography techniques, restricting sample-to-sensor distance smaller than ~ 0.5 micron and SQUIDs diameters smaller than ~ 200 nm. These limitations were overcome by the invention of a SQUID-on-tip device, subsequent realization of a SQUID-on-tip microscope, and by creation of an ultra-small sensor with spatial resolution of 20 nm and sensitivity to a single electron spin per 1 Hz bandwidth. In this talk I will describe the principles of scanning SQUID magnetometry, its applications to study superconductors and its potential for magnetic nano-scale imaging of novel materials.

  13. Impact parameter dependent potentials and transverse single spin asymmetries

    NASA Astrophysics Data System (ADS)

    Alhalholy, Tareq

    Using the Eikonal approximation, we study single spin azimuthal asymmetry in elastic and in-elastic lepton-nucleon scattering for the case of transversely polarized nucleons with unpolarized lepton beam. We follow two different approaches to evaluate the asymmetry. In the first approach we utilize the convolution theory of Fourier transforms to express the nucleon potential that appears in the Coulomb phase formula in terms of the nucleon's Dirac and Pauli form factors in the nucleon current density for transversely polarized nucleons. In the second approach, we explicitly evaluate the potential due to transversely polarized nucleons in impact parameter space. The result shows that this potential is asymmetric about an axis normal to the transverse plane; a result that is consistent with the fact that the nucleon charge density (or the unpolarized impact parameter dependent parton distribution function) is transversely distorted for transverse nucleon polarization, which is not the case for longitudinal polarization of the nucleon. To further confirm this fact, we calculate the average transverse momentum experienced by the scattered electron. This quantity is zero considering scattering from a classical dipole moment while our results show a non-zero average transverse momentum even for scattering from a neutron; there we get a negative value for the average momentum, and a positive one (and larger in magnitude) for the case of a proton. The sign of the average transverse momentum is directly related to the sign of the single spin asymmetry, where it is negative in the case of a neutron target and positive for a proton. The expansion of the Eikonal amplitude reveals that the asymmetry is due to the interference of the one and two photon exchange Eikonal amplitudes. In both of the above mentioned approaches, we evaluate the one and two photon exchange amplitudes, from which the asymmetry is found for different parametrizations of the form factors.

  14. Protecting nickel with graphene spin-filtering membranes: A single layer is enough

    SciTech Connect

    Martin, M.-B.; Dlubak, B.; Piquemal-Banci, M.; Collin, S.; Petroff, F.; Anane, A.; Fert, A.; Seneor, P.; Yang, H.; Blume, R.; Schloegl, R.

    2015-07-06

    We report on the demonstration of ferromagnetic spin injectors for spintronics which are protected against oxidation through passivation by a single layer of graphene. The graphene monolayer is directly grown by catalytic chemical vapor deposition on pre-patterned nickel electrodes. X-ray photoelectron spectroscopy reveals that even with its monoatomic thickness, monolayer graphene still efficiently protects spin sources against oxidation in ambient air. The resulting single layer passivated electrodes are integrated into spin valves and demonstrated to act as spin polarizers. Strikingly, the atom-thick graphene layer is shown to be sufficient to induce a characteristic spin filtering effect evidenced through the sign reversal of the measured magnetoresistance.

  15. Protecting nickel with graphene spin-filtering membranes: A single layer is enough

    NASA Astrophysics Data System (ADS)

    Martin, M.-B.; Dlubak, B.; Weatherup, R. S.; Piquemal-Banci, M.; Yang, H.; Blume, R.; Schloegl, R.; Collin, S.; Petroff, F.; Hofmann, S.; Robertson, J.; Anane, A.; Fert, A.; Seneor, P.

    2015-07-01

    We report on the demonstration of ferromagnetic spin injectors for spintronics which are protected against oxidation through passivation by a single layer of graphene. The graphene monolayer is directly grown by catalytic chemical vapor deposition on pre-patterned nickel electrodes. X-ray photoelectron spectroscopy reveals that even with its monoatomic thickness, monolayer graphene still efficiently protects spin sources against oxidation in ambient air. The resulting single layer passivated electrodes are integrated into spin valves and demonstrated to act as spin polarizers. Strikingly, the atom-thick graphene layer is shown to be sufficient to induce a characteristic spin filtering effect evidenced through the sign reversal of the measured magnetoresistance.

  16. Electron spin echo and spin relaxation of low-symmetry Mn(2+)-complexes in ammonium oxalate monohydrate single crystal.

    PubMed

    Hoffmann, Stanisław K; Lijewski, Stefan; Goslar, Janina; Mielniczek-Brzóska, Ewa

    2014-09-01

    Pulse EPR experiments were performed on low concentration Mn(2+) ions in ammonium oxalate monohydrate single crystals at X-band, in the temperature range 4.2-60K at crystal orientation close to the D-tensor z-axis. Hyperfine lines of the resolved spin transitions were selectively excited by short nanosecond pulses. Electron spin echo signal was not observed for the low spin transition (+5/2↔+3/2) suggesting a magnetic field threshold for the echo excitation. Echo appears for higher spin transitions with amplitude, which grows with magnetic field. Opposite behavior displays amplitude of echo decay modulations, which is maximal at low field and negligible for high field spin transitions. Electron spin-lattice relaxation was measured by the pulse saturation method. After the critical analysis of possible relaxation processes it was concluded that the relaxation is governed by Raman T(7)-process. The relaxation is the same for all spin transitions except the lowest temperatures (below 20K) where the high field transitions (-3/2↔-1/2) and (-5/2↔-3/2) have a slower relaxation rate. Electron spin echo dephasing is produced by electron spectral diffusion mainly, with a small contribution from instantaneous diffusion for all spin transitions. For the highest field transition (-5/2↔-3/2) an additional contribution from nuclear spectral diffusion appears with resonance type enhancement at low temperatures.

  17. Internal Spin Control, Squeezing and Decoherence in Ensembles of Alkali Atomic Spins

    NASA Astrophysics Data System (ADS)

    Norris, Leigh Morgan

    Large atomic ensembles interacting with light are one of the most promising platforms for quantum information processing. In the past decade, novel applications for these systems have emerged in quantum communication, quantum computing, and metrology. Essential to all of these applications is the controllability of the atomic ensemble, which is facilitated by a strong coupling between the atoms and light. Non-classical spin squeezed states are a crucial step in attaining greater ensemble control. The degree of entanglement present in these states, furthermore, serves as a benchmark for the strength of the atom-light interaction. Outside the broader context of quantum information processing with atomic ensembles, spin squeezed states have applications in metrology, where their quantum correlations can be harnessed to improve the precision of magnetometers and atomic clocks. This dissertation focuses upon the production of spin squeezed states in large ensembles of cold trapped alkali atoms interacting with optical fields. While most treatments of spin squeezing consider only the case in which the ensemble is composed of two level systems or qubits, we utilize the entire ground manifold of an alkali atom with hyperfine spin f greater or equal to 1/2, a qudit. Spin squeezing requires non-classical correlations between the constituent atomic spins, which are generated through the atoms' collective coupling to the light. Either through measurement or multiple interactions with the atoms, the light mediates an entangling interaction that produces quantum correlations. Because the spin squeezing treated in this dissertation ultimately originates from the coupling between the light and atoms, conventional approaches of improving this squeezing have focused on increasing the optical density of the ensemble. The greater number of internal degrees of freedom and the controllability of the spin-f ground hyperfine manifold enable novel methods of enhancing squeezing. In

  18. Internal Spin Control, Squeezing and Decoherence in Ensembles of Alkali Atomic Spins

    NASA Astrophysics Data System (ADS)

    Norris, Leigh Morgan

    Large atomic ensembles interacting with light are one of the most promising platforms for quantum information processing. In the past decade, novel applications for these systems have emerged in quantum communication, quantum computing, and metrology. Essential to all of these applications is the controllability of the atomic ensemble, which is facilitated by a strong coupling between the atoms and light. Non-classical spin squeezed states are a crucial step in attaining greater ensemble control. The degree of entanglement present in these states, furthermore, serves as a benchmark for the strength of the atom-light interaction. Outside the broader context of quantum information processing with atomic ensembles, spin squeezed states have applications in metrology, where their quantum correlations can be harnessed to improve the precision of magnetometers and atomic clocks. This dissertation focuses upon the production of spin squeezed states in large ensembles of cold trapped alkali atoms interacting with optical fields. While most treatments of spin squeezing consider only the case in which the ensemble is composed of two level systems or qubits, we utilize the entire ground manifold of an alkali atom with hyperfine spin f greater than or equal to 1/2, a qudit. Spin squeezing requires non-classical correlations between the constituent atomic spins, which are generated through the atoms' collective coupling to the light. Either through measurement or multiple interactions with the atoms, the light mediates an entangling interaction that produces quantum correlations. Because the spin squeezing treated in this dissertation ultimately originates from the coupling between the light and atoms, conventional approaches of improving this squeezing have focused on increasing the optical density of the ensemble. The greater number of internal degrees of freedom and the controllability of the spin-f ground hyperfine manifold enable novel methods of enhancing squeezing. In

  19. Quantum interference of stored dual-channel spin-wave excitations in a single tripod system

    SciTech Connect

    Wang Hai; Li Shujing; Xu Zhongxiao; Zhao Xingbo; Zhang Lijun; Li Jiahua; Wu Yuelong; Xie Changde; Peng Kunchi; Xiao Min

    2011-04-15

    We present an experimental demonstration of dual-channel memory in a single tripod atomic system. The total readout signal exhibits either constructive or destructive interference when the dual-channel spin-wave excitations (SWEs) are retrieved by two reading beams with a controllable relative phase. When the two reading beams have opposite phases, the SWEs will remain in the medium, which can be retrieved later with two in-phase reading beams. Such a phase-sensitive storage and retrieval scheme can be used to measure and control the relative phase between the two SWEs in the memory medium, which may find applications in quantum-information processing.

  20. Single transverse spin asymmetries in semi-inclusive deep inelastic scattering in a spin-1 diquark model

    NASA Astrophysics Data System (ADS)

    Kumar, Narinder; Dahiya, Harleen

    2015-04-01

    The observed results for the azimuthal single spin asymmetries (SSAs) of the proton, measured in the semi-inclusive deep inelastic scattering (SIDIS), can be explained by the final-state interaction (FSI) from the gluon exchange between the outgoing quark and the target spectator system. SSAs require a phase difference between two amplitudes coupling the target with opposite spins to the same final state. We have used the model of light front wave functions (LFWFs) consisting of a spin- system as a composite of a spin- fermion and a spin-1 vector boson to estimate the SSAs. The implications of such a model have been investigated in detail by considering different coupling constants. The FSIs also produce a complex phase which can be included in the LFWFs to calculate the Sivers and Boer-Mulders distribution functions of the nucleon.

  1. Terahertz spin current pulses controlled by magnetic heterostructures.

    PubMed

    Kampfrath, T; Battiato, M; Maldonado, P; Eilers, G; Nötzold, J; Mährlein, S; Zbarsky, V; Freimuth, F; Mokrousov, Y; Blügel, S; Wolf, M; Radu, I; Oppeneer, P M; Münzenberg, M

    2013-04-01

    In spin-based electronics, information is encoded by the spin state of electron bunches. Processing this information requires the controlled transport of spin angular momentum through a solid, preferably at frequencies reaching the so far unexplored terahertz regime. Here, we demonstrate, by experiment and theory, that the temporal shape of femtosecond spin current bursts can be manipulated by using specifically designed magnetic heterostructures. A laser pulse is used to drive spins from a ferromagnetic iron thin film into a non-magnetic cap layer that has either low (ruthenium) or high (gold) electron mobility. The resulting transient spin current is detected by means of an ultrafast, contactless amperemeter based on the inverse spin Hall effect, which converts the spin flow into a terahertz electromagnetic pulse. We find that the ruthenium cap layer yields a considerably longer spin current pulse because electrons are injected into ruthenium d states, which have a much lower mobility than gold sp states. Thus, spin current pulses and the resulting terahertz transients can be shaped by tailoring magnetic heterostructures, which opens the door to engineering high-speed spintronic devices and, potentially, broadband terahertz emitters.

  2. Electron spin control of optically levitated nanodiamonds in vacuum

    NASA Astrophysics Data System (ADS)

    Hoang, Thai; Ahn, Jonghoon; Bang, Jaehoon; Li, Tongcang

    2016-05-01

    Electron spins of diamond nitrogen-vacancy (NV) centers are important quantum resources for nanoscale sensing and quantum information. Combining such NV spin systems with levitated optomechanical resonators will provide a hybrid quantum system for many novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centers in low vacuum. We observe that the strength of electron spin resonance (ESR) is enhanced when the air pressure is reduced. To better understand this novel system, we also investigate the effects of trap power and measure the absolute internal temperature of levitated nanodiamonds with ESR after calibration of the strain effect.

  3. Polarization Dependence of the Spin-Density-Wave Excitations in Single-Domain Chromium

    SciTech Connect

    Boeni, P.; Sternlieb, B.J.; Shirane, G.; Roessli, B.; Werner, S.A.; Lorenzo, J.E.

    1997-12-31

    A polarised neutron scattering experiment has been performed on a single-Q, single domain sample of Cr in a magnetic field of 4 T in the transverse spin-density-wave phase. It is confirmed that the longitudinal fluctuations are enhanced for energy transfers E {lt} 8 meV similarly as in the longitudinal spin-density-wave phase. The spin wave modes with deltaS parallel and perpendicular to Q are isotropic within the E-range investigated.

  4. Efficient spin filter and spin valve in a single-molecule magnet Fe{sub 4} between two graphene electrodes

    SciTech Connect

    Zu, Feng-Xia; Gao, Guo-Ying; Fu, Hua-Hua; Peng, Li; Yao, Kai-Lun; Xiong, Lun; Zhu, Si-Cong

    2015-12-21

    We propose a magnetic molecular junction consisting of a single-molecule magnet Fe{sub 4} connected two graphene electrodes and investigate transport properties, using the nonequilibrium Green's function method in combination with spin-polarized density-functional theory. The results show that the device can be used as a nearly perfect spin filter with efficiency approaching 100%. Our calculations provide crucial microscopic information how the four iron cores of the chemical structure are responsible for the spin-resolved transmissions. Moreover, it is also found that the device behaves as a highly efficient spin valve, which is an excellent candidate for spintronics of molecular devices. The idea of combining single-molecule magnets with graphene provides a direction in designing a new class of molecular spintronic devices.

  5. Nearly Perfect Spin Filter, Spin Valve and Negative Differential Resistance Effects in a Fe4-based Single-molecule Junction

    PubMed Central

    Zu, Fengxia; Liu, Zuli; Yao, Kailun; Gao, Guoying; Fu, Huahua; Zhu, Sicong; Ni, Yun; Peng, Li

    2014-01-01

    The spin-polarized transport in a single-molecule magnet Fe4 sandwiched between two gold electrodes is studied, using nonequilibrium Green's functions in combination with the density-functional theory. We predict that the device possesses spin filter effect (SFE), spin valve effect (SVE), and negative differential resistance (NDR) behavior. Moreover, we also find that the appropriate chemical ligand, coupling the single molecule to leads, is a key factor for manipulating spin-dependent transport. The device containing the methyl ligand behaves as a nearly perfect spin filter with efficiency approaching 100%, and the transport is dominated by transmission through the Fe4 metal center. However, in the case of phenyl ligand, the spin filter effect seems to be reduced, but the spin valve effect is significantly enhanced with a large magnetoresistance ratio, reaching 1800%. This may be attributed to the blocking effect of the phenyl ligands in mediating transport. Our findings suggest that such a multifunctional molecular device, possessing SVE, NDR and high SFE simultaneously, would be an excellent candidate for spintronics of molecular devices. PMID:24787446

  6. Nearly perfect spin filter, spin valve and negative differential resistance effects in a Fe4-based single-molecule junction.

    PubMed

    Zu, Fengxia; Liu, Zuli; Yao, Kailun; Gao, Guoying; Fu, Huahua; Zhu, Sicong; Ni, Yun; Peng, Li

    2014-01-01

    The spin-polarized transport in a single-molecule magnet Fe4 sandwiched between two gold electrodes is studied, using nonequilibrium Green's functions in combination with the density-functional theory. We predict that the device possesses spin filter effect (SFE), spin valve effect (SVE), and negative differential resistance (NDR) behavior. Moreover, we also find that the appropriate chemical ligand, coupling the single molecule to leads, is a key factor for manipulating spin-dependent transport. The device containing the methyl ligand behaves as a nearly perfect spin filter with efficiency approaching 100%, and the transport is dominated by transmission through the Fe4 metal center. However, in the case of phenyl ligand, the spin filter effect seems to be reduced, but the spin valve effect is significantly enhanced with a large magnetoresistance ratio, reaching 1800%. This may be attributed to the blocking effect of the phenyl ligands in mediating transport. Our findings suggest that such a multifunctional molecular device, possessing SVE, NDR and high SFE simultaneously, would be an excellent candidate for spintronics of molecular devices. PMID:24787446

  7. General Features of Single-Spin Asymmetry in Inclusive Pion Production in Fixed-Target Experiments

    SciTech Connect

    Vasiliev, A.N.; Mochalov, V.V.

    2004-12-01

    The results of various experiments that measured a single-spin asymmetry in inclusive pion production are analyzed in the energy range between 13 and 200 GeV. The experimental fact that the single-spin asymmetry begins increasing at one universal value of the pion energy in the c.m. frame is established.

  8. Dual-spin attitude control for outer planet missions

    NASA Technical Reports Server (NTRS)

    Ward, R. S.; Tauke, G. J.

    1977-01-01

    The applicability of dual-spin technology to a Jupiter orbiter with probe mission was investigated. Basic mission and system level attitude control requirements were established and preliminary mechanization and control concepts developed. A comprehensive 18-degree-of-freedom digital simulation was utilized extensively to establish control laws, study dynamic interactions, and determined key sensitivities. Fundamental system/subsystem constraints were identified, and the applicability of dual-spin technology to a Jupiter orbiter with probe mission was validated.

  9. Initialization of a spin qubit in a site-controlled nanowire quantum dot

    NASA Astrophysics Data System (ADS)

    Lagoudakis, Konstantinos G.; McMahon, Peter L.; Fischer, Kevin A.; Puri, Shruti; Müller, Kai; Dalacu, Dan; Poole, Philip J.; Reimer, Michael E.; Zwiller, Val; Yamamoto, Yoshihisa; Vučković, Jelena

    2016-05-01

    A fault-tolerant quantum repeater or quantum computer using solid-state spin-based quantum bits will likely require a physical implementation with many spins arranged in a grid. Self-assembled quantum dots (QDs) have been established as attractive candidates for building spin-based quantum information processing devices, but such QDs are randomly positioned, which makes them unsuitable for constructing large-scale processors. Recent efforts have shown that QDs embedded in nanowires can be deterministically positioned in regular arrays, can store single charges, and have excellent optical properties, but so far there have been no demonstrations of spin qubit operations using nanowire QDs. Here we demonstrate optical pumping of individual spins trapped in site-controlled nanowire QDs, resulting in high-fidelity spin-qubit initialization. This represents the next step towards establishing spins in nanowire QDs as quantum memories suitable for use in a large-scale, fault-tolerant quantum computer or repeater based on all-optical control of the spin qubits.

  10. Charge-Insensitive Single-Atom Spin-Orbit Qubit in Silicon.

    PubMed

    Salfi, Joe; Mol, Jan A; Culcer, Dimitrie; Rogge, Sven

    2016-06-17

    High fidelity entanglement of an on-chip array of spin qubits poses many challenges. Spin-orbit coupling (SOC) can ease some of these challenges by enabling long-ranged entanglement via electric dipole-dipole interactions, microwave photons, or phonons. However, SOC exposes conventional spin qubits to decoherence from electrical noise. Here, we propose an acceptor-based spin-orbit qubit in silicon offering long-range entanglement at a sweet spot where the qubit is protected from electrical noise. The qubit relies on quadrupolar SOC with the interface and gate potentials. As required for surface codes, 10^{5} electrically mediated single-qubit and 10^{4} dipole-dipole mediated two-qubit gates are possible in the predicted spin lifetime. Moreover, circuit quantum electrodynamics with single spins is feasible, including dispersive readout, cavity-mediated entanglement, and spin-photon entanglement. An industrially relevant silicon-based platform is employed. PMID:27367400

  11. Charge-Insensitive Single-Atom Spin-Orbit Qubit in Silicon

    NASA Astrophysics Data System (ADS)

    Salfi, Joe; Mol, Jan A.; Culcer, Dimitrie; Rogge, Sven

    2016-06-01

    High fidelity entanglement of an on-chip array of spin qubits poses many challenges. Spin-orbit coupling (SOC) can ease some of these challenges by enabling long-ranged entanglement via electric dipole-dipole interactions, microwave photons, or phonons. However, SOC exposes conventional spin qubits to decoherence from electrical noise. Here, we propose an acceptor-based spin-orbit qubit in silicon offering long-range entanglement at a sweet spot where the qubit is protected from electrical noise. The qubit relies on quadrupolar SOC with the interface and gate potentials. As required for surface codes, 105 electrically mediated single-qubit and 104 dipole-dipole mediated two-qubit gates are possible in the predicted spin lifetime. Moreover, circuit quantum electrodynamics with single spins is feasible, including dispersive readout, cavity-mediated entanglement, and spin-photon entanglement. An industrially relevant silicon-based platform is employed.

  12. A quantum phase switch between a single solid-state spin and a photon.

    PubMed

    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.

  13. Room temperature high-fidelity holonomic single-qubit gate on a solid-state spin

    PubMed Central

    Arroyo-Camejo, Silvia; Lazariev, Andrii; Hell, Stefan W.; Balasubramanian, Gopalakrishnan

    2014-01-01

    At its most fundamental level, circuit-based quantum computation relies on the application of controlled phase shift operations on quantum registers. While these operations are generally compromised by noise and imperfections, quantum gates based on geometric phase shifts can provide intrinsically fault-tolerant quantum computing. Here we demonstrate the high-fidelity realization of a recently proposed fast (non-adiabatic) and universal (non-Abelian) holonomic single-qubit gate, using an individual solid-state spin qubit under ambient conditions. This fault-tolerant quantum gate provides an elegant means for achieving the fidelity threshold indispensable for implementing quantum error correction protocols. Since we employ a spin qubit associated with a nitrogen-vacancy colour centre in diamond, this system is based on integrable and scalable hardware exhibiting strong analogy to current silicon technology. This quantum gate realization is a promising step towards viable, fault-tolerant quantum computing under ambient conditions. PMID:25216026

  14. Single-Molecule Spin Switch Based on Voltage-Triggered Distortion of the Coordination Sphere.

    PubMed

    Harzmann, Gero D; Frisenda, Riccardo; van der Zant, Herre S J; Mayor, Marcel

    2015-11-01

    Here, we report on a new single-molecule-switching concept based on the coordination-sphere-dependent spin state of Fe(II) species. The perpendicular arrangement of two terpyridine (tpy) ligands within heteroleptic complexes is distorted by the applied electric field. Whereas one ligand fixes the complex in the junction, the second one exhibits an intrinsic dipole moment which senses the E field and causes the distortion of the Fe(II) coordination sphere triggering the alteration of its spin state. A series of complexes with different dipole moments have been synthesized and their transport features were investigated via mechanically controlled break-junctions. Statistical analyses support the hypothesized switching mechanism with increasing numbers of junctions displaying voltage-dependent bistabilities upon increasing the Fe(II) complexes' intrinsic dipole moments. A constant threshold value of the E field required for switching corroborates the mechanism. PMID:26426777

  15. Active control of magnetoresistance of organic spin valves using ferroelectricity

    PubMed Central

    Sun, Dali; Fang, Mei; Xu, Xiaoshan; Jiang, Lu; Guo, Hangwen; Wang, Yanmei; Yang, Wenting; Yin, Lifeng; Snijders, Paul C.; Ward, T. Z.; Gai, Zheng; Zhang, X.-G.; Lee, Ho Nyung; Shen, Jian

    2014-01-01

    Organic spintronic devices have been appealing because of the long spin lifetime of the charge carriers in the organic materials and their low cost, flexibility and chemical diversity. In previous studies, the control of resistance of organic spin valves is generally achieved by the alignment of the magnetization directions of the two ferromagnetic electrodes, generating magnetoresistance. Here we employ a new knob to tune the resistance of organic spin valves by adding a thin ferroelectric interfacial layer between the ferromagnetic electrode and the organic spacer: the magnetoresistance of the spin valve depends strongly on the history of the bias voltage, which is correlated with the polarization of the ferroelectric layer; the magnetoresistance even changes sign when the electric polarization of the ferroelectric layer is reversed. These findings enable active control of resistance using both electric and magnetic fields, opening up possibility for multi-state organic spin valves. PMID:25008155

  16. Active control of magnetoresistance of organic spin valves using ferroelectricity.

    PubMed

    Sun, Dali; Fang, Mei; Xu, Xiaoshan; Jiang, Lu; Guo, Hangwen; Wang, Yanmei; Yang, Wenting; Yin, Lifeng; Snijders, Paul C; Ward, T Z; Gai, Zheng; Zhang, X-G; Lee, Ho Nyung; Shen, Jian

    2014-01-01

    Organic spintronic devices have been appealing because of the long spin lifetime of the charge carriers in the organic materials and their low cost, flexibility and chemical diversity. In previous studies, the control of resistance of organic spin valves is generally achieved by the alignment of the magnetization directions of the two ferromagnetic electrodes, generating magnetoresistance. Here we employ a new knob to tune the resistance of organic spin valves by adding a thin ferroelectric interfacial layer between the ferromagnetic electrode and the organic spacer: the magnetoresistance of the spin valve depends strongly on the history of the bias voltage, which is correlated with the polarization of the ferroelectric layer; the magnetoresistance even changes sign when the electric polarization of the ferroelectric layer is reversed. These findings enable active control of resistance using both electric and magnetic fields, opening up possibility for multi-state organic spin valves. PMID:25008155

  17. Active control of magnetoresistance of organic spin valves using ferroelectricity

    NASA Astrophysics Data System (ADS)

    Shen, Jian

    Organic spintronic devices have been appealing because of the long spin lifetime of the charge carriers in the organic materials and their low cost, flexibility and chemical diversity. In previous studies, the control of resistance of organic spin valves is generally achieved by the alignment of the magnetization directions of the two ferromagnetic electrodes, generating magnetoresistance. Here we employ a new knob to tune the resistance of organic spin valves by adding a thin ferroelectric interfacial layer between the ferromagnetic electrode and the organic spacer: the magnetoresistance of the spin valve depends strongly on the history of the bias voltage, which is correlated with the polarization of the ferroelectric layer; the magnetoresistance even changes sign when the electric polarization of the ferroelectric layer is reversed. These findings enable active control of resistance using both electric and magnetic fields, opening up possibility for multi-state organic spin valves.

  18. Control of propagating spin waves via spin transfer torque in a metallic bilayer waveguide

    NASA Astrophysics Data System (ADS)

    An, Kyongmo; Birt, Daniel R.; Pai, Chi-Feng; Olsson, Kevin; Ralph, Daniel C.; Buhrman, Robert A.; Li, Xiaoqin

    2014-04-01

    We investigate the effect of a direct current on propagating spin waves in a CoFeB/Ta bilayer structure. Using the micro-Brillouin light scattering technique, we observe that the spin-wave damping and amplitude may be attenuated or amplified depending on the direction of the current and the applied magnetic field. Our work suggests an effective approach for electrically controlling the propagation of spin waves in a magnetic waveguide and may be useful in a number of applications such as phase-locked nano-oscillators and hybrid information-processing devices.

  19. Spin-controlled mechanics in nanoelectromechanical systems

    NASA Astrophysics Data System (ADS)

    Radić, D.

    2015-03-01

    We consider a dc-electronic tunneling transport through a carbon nanotube suspended between normal-metal source and arbitrarily spin-polarized drain lead in the presence of an external magnetic field. We show that magnetomotive coupling between electrical current through the nanotube and its mechanical vibrations may lead to an electromechanical instability and give an onset of self-excited mechanical vibrations depending on spin polarization of the drain lead and frequency of vibrations. The self-excitation mechanism is based on correlation between the occupancy of quantized Zeeman-split electronic states in the nanotube and the direction of velocity of its mechanical motion. It is an effective gating effect by the presence of electron in the spin state which, through the Coulomb blockade, permits tunneling of electron to the drain predominantly only during a particular phase of mechanical vibration thus coherently changing mechanical momentum and leading into instability if mechanical damping is overcome.

  20. Experimental Study of Single Spin Asymmetries and TMDs

    NASA Astrophysics Data System (ADS)

    Chen, Jian-Ping

    2014-01-01

    Single Spin Asymmetries and Transverse Momentum Dependent (TMD) distribution study has been one of the main focuses of hadron physics in recent years. The initial exploratory Semi-Inclusive Deep-Inelastic-Scattering (SIDIS) experiments with transversely polarized proton and deuteron targets from HERMES and COMPASS attracted great attention and lead to very active efforts in both experiments and theory. A SIDIS experiment on the neutron with a polarized 3He target was performed at JLab. Recently published results as well as new preliminary results are shown. Precision TMD experiments are planned at JLab after the 12 GeV energy upgrade. Three approved experiments with a new SoLID spectrometer on both the proton and neutron will provide high precision TMD data in the valence quark region. In the long-term future, an Electron-Ion Collider (EIC) as proposed in US (MEIC@JLab and E-RHIC@BNL) will provide precision TMD data of the gluons and the sea. A new opportunity just emerged in China that a low-energy EIC (1st stage EIC@HIAF) may provide precision TMD data in the sea quark region, complementary to the proposed EIC in US.

  1. Spin-path entanglement in single-neutron interferometer experiments

    SciTech Connect

    Hasegawa, Yuji; Erdoesi, Daniel

    2011-09-23

    There are two powerful arguments against the possibility of extending quantum mechanics (QM) into a more fundamental theory yielding a deterministic description of nature. One is the experimental violation of Bell inequalities, which discards local hidden-variable theories as a possible extension to QM. The other is the Kochen-Specker (KS) theorem, which stresses the incompatibility of QM with a larger class of hidden-variable theories, known as noncontextual hidden-variable theories. We performed experiments with neutron interferometer, which exploits spin-path entanglements in single neutrons. A Bell-like state is generated to demonstrate a violation of the Bell-like inequality and phenomena in accordance with KS theorem: both experiments study quantum contextuality and show clear evidence of the incompatibility of noncontextual hidden variable theories with QM. The value S = 2.202{+-}0.007 Neither-Less-Than-Nor-Equal-To 2 is obtained in the new measurement of the Bell-like inequality, which shows a larger violation than the previous measurement. For the study of KS theorem, the obtained violation 2.291{+-}0.008 Neither-Less-Than-Nor-Equal-To 1 clearly shows that quantum mechanical predictions cannot be reproduced by noncontextual hidden variable theories.

  2. Global fitting of single spin asymmetry: An attempt

    NASA Astrophysics Data System (ADS)

    Kang, Zhong-Bo; Prokudin, Alexei

    2012-04-01

    We present an attempt of global analysis of semi-inclusive deep inelastic scattering ℓp↑→ℓ'πX data on single spin asymmetries and data on left-right asymmetry AN in p↑p→πX in order to simultaneously extract information on the Sivers function and the twist-three quark-gluon Efremov-Teryaev-Qiu-Sterman function. We explore different possibilities such as the node of the Sivers function in x or k⊥ in order to explain “sign mismatch” between these functions. We show that π± semi-inclusive deep inelastic scattering data and π0 STAR data can be well described in a combined fit based on both the transverse momentum dependent and collinear twist-three factorization formalisms; however, π± BRAHMS data are not described in a satisfactory way. This leaves the question open of a solution to the “sign mismatch.” Possible explanations are then discussed.

  3. Spin-controlled plasmonics via optical Rashba effect

    SciTech Connect

    Shitrit, Nir; Yulevich, Igor; Kleiner, Vladimir; Hasman, Erez

    2013-11-18

    Observation of the optical Rashba effect in plasmonics is reported. Polarization helicity degeneracy removal, associated with the inversion symmetry violation, is attributed to the surface symmetry design via anisotropic nanoantennas with space-variant orientations. By utilizing the Rashba-induced momentum in a nanoscale kagome metastructure, we demonstrated a spin-based surface plasmon multidirectional excitation under a normal-incidence illumination. The spin-controlled plasmonics via spinoptical metasurfaces provides a route for spin-based surface-integrated photonic nanodevices and light-matter interaction control, extending the light manipulation capabilities.

  4. Wide-band nanoscale magnetic resonance spectroscopy using quantum relaxation of a single spin in diamond

    NASA Astrophysics Data System (ADS)

    Wood, James D. A.; Broadway, David A.; Hall, Liam T.; Stacey, Alastair; Simpson, David A.; Tetienne, Jean-Philippe; Hollenberg, Lloyd C. L.

    2016-10-01

    We demonstrate an all-optical approach of nanoscale magnetic resonance (MR) spectroscopy whereby quantum relaxation (T1) of a single probe spin in diamond is monitored during a precise static magnetic field sweep to construct a spectrum of the surrounding spin environment. The method is inherently noninvasive as it involves no driving fields, and instead relies on the natural resonance between the quantum probe and target spins. As a proof of concept, we measure the T1-MR spectra across a wide band [megahertz (MHz) to gigahertz (GHz)] of a small ensemble of 14N impurities surrounding a single probe spin, providing information on both electron spin transitions (in the GHz range) and nuclear spin transitions (in the MHz range) of the 14N spin targets. Analysis of the T1-MR spectrum reveals that the electron spin transitions are probed via dipole interactions with the probe, while the relatively weak nuclear spin resonances are dramatically enhanced by hyperfine coupling in an electron-mediated process. With a projected sensitivity to external single-proton spins, this work establishes T1-MR as a powerful noninvasive wide-band technique for nanoscale MR spectroscopy.

  5. Quantum Control of Nuclear Spins Coupled to Nitrogen-Vacancy Centers in Diamond

    NASA Astrophysics Data System (ADS)

    Sangtawesin, Sorawis

    This dissertation presents experiments on nitrogen-vacancy (NV) defect centers in diamond. The NV center is an optically active color center formed by one substitutional nitrogen atom and an adjacent vacancy in the diamond lattice. Its ground state spin triplet transitions are accessible in the microwave regime and their corresponding excited state transitions exhibit spin-dependent fluorescence that allows for optical spin state readout. We present methods for the deterministic placement and the fine tuning of the NV center population in bulk diamond via ion implantation. We demonstrate quantum control of the nuclear spin in diamond through manipulation of the NV center electronic spin. By utilizing the hyperfine coupling between the electronic and nuclear spins, fast phase gates on the intrinsic nitrogen nuclear spin can be achieved within half a microsecond, a speed that far exceeds that of the gates performed with conventional nuclear magnetic resonance pulses. The hyperfine coupling also results in an enhancement of the effective nuclear gyromagnetic ratio. We demonstrate the tunability of this enhancement by changing the magnetic field. Finally, we discuss preliminary experiments aimed towards coupling a single NV center to higher nuclear spin systems.

  6. Spin-related thermoelectric conversion in lateral spin-valve devices with single-crystalline Co2FeSi electrodes

    NASA Astrophysics Data System (ADS)

    Yamasaki, Kento; Oki, Soichiro; Yamada, Shinya; Kanashima, Takeshi; Hamaya, Kohei

    2015-04-01

    We demonstrate the conversion between a heat current and a spin current in Cu-based lateral spin valves (LSVs) with single-crystalline Co2FeSi (CFS) electrodes. We can observe the thermally induced spin injection from CFS into Cu resulting from the spin-dependent Seebeck effect, and the heat current generated by the spin-dependent Peltier effect can be detected even in the LSV structures. This study is an important step toward understanding heat-spin conversion in single-crystalline materials with various electronic band structures.

  7. Spin Models for Packet Routing Control in Computer Networks

    NASA Astrophysics Data System (ADS)

    Horiguchi, T.

    We investigate packet flow in computer networks within the framework of statistical physics by using numerical simulations. As mathematical models for packet routing, we present a spin model with lattice gas spins and the one with Ising spins. Then we propose dynamic programming for optimal routing control of packet flow by using the two spin models. This is a kind of goal-directed learning for taking into account of time-dependent environment for the packets. Next we investigate a congestion problem by using the model with lattice gas spins when the packets are not sent to nodes at which their buffers are already full up with packets. Since we have found serious congestion in the packet flow, we then propose reinforcement learning for avoiding the congestion and have performed simulations on several networks including small world networks, scale free networks and so on.

  8. Electron spin control of optically levitated nanodiamonds in vacuum.

    PubMed

    Hoang, Thai M; Ahn, Jonghoon; Bang, Jaehoon; Li, Tongcang

    2016-01-01

    Electron spins of diamond nitrogen-vacancy (NV) centres are important quantum resources for nanoscale sensing and quantum information. Combining NV spins with levitated optomechanical resonators will provide a hybrid quantum system for novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centres in low vacuum. We observe that the strength of electron spin resonance (ESR) is enhanced when the air pressure is reduced. To better understand this system, we investigate the effects of trap power and measure the absolute internal temperature of levitated nanodiamonds with ESR after calibration of the strain effect. We also observe that oxygen and helium gases have different effects on both the photoluminescence and the ESR contrast of nanodiamond NV centres, indicating potential applications of NV centres in oxygen gas sensing. Our results pave the way towards a levitated spin-optomechanical system for studying macroscopic quantum mechanics. PMID:27432560

  9. Electron spin control of optically levitated nanodiamonds in vacuum

    NASA Astrophysics Data System (ADS)

    Hoang, Thai M.; Ahn, Jonghoon; Bang, Jaehoon; Li, Tongcang

    2016-07-01

    Electron spins of diamond nitrogen-vacancy (NV) centres are important quantum resources for nanoscale sensing and quantum information. Combining NV spins with levitated optomechanical resonators will provide a hybrid quantum system for novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centres in low vacuum. We observe that the strength of electron spin resonance (ESR) is enhanced when the air pressure is reduced. To better understand this system, we investigate the effects of trap power and measure the absolute internal temperature of levitated nanodiamonds with ESR after calibration of the strain effect. We also observe that oxygen and helium gases have different effects on both the photoluminescence and the ESR contrast of nanodiamond NV centres, indicating potential applications of NV centres in oxygen gas sensing. Our results pave the way towards a levitated spin-optomechanical system for studying macroscopic quantum mechanics.

  10. Gate-controlled electron spins in quantum dots

    SciTech Connect

    Prabhakar, Sanjay; Melnik, Roderick; Bonilla, Luis L.

    2013-12-16

    In this paper we study the properties of anisotropic semiconductor quantum dots (QDs) formed in the conduction band in the presence of the magnetic field. The Kane-type model is formulated and is analyzed by using both analytical and finite element techniques. Among other things, we demonstrate that in such quantum dots, the electron spin states in the phonon-induced spin-flip rate can be manipulated with the application of externally applied anisotropic gate potentials. More precisely, such potentials enhance the spin flip rates and reduce the level crossing points to lower quantum dot radii. This happens due to the suppression of the g-factor towards bulk crystal. We conclude that the phonon induced spin-flip rate can be controlled through the application of spin-orbit coupling. Numerical examples are shown to demonstrate these findings.

  11. Electric control of spin injection into a ferroelectric semiconductor.

    PubMed

    Liu, Xiaohui; Burton, J D; Zhuravlev, M Ye; Tsymbal, Evgeny Y

    2015-01-30

    Electric-field control of spin-dependent properties has become one of the most attractive phenomena in modern materials research due to the promise of new device functionalities. One of the paradigms in this approach is to electrically toggle the spin polarization of carriers injected into a semiconductor using ferroelectric polarization as a control parameter. Using first-principles density-functional calculations, we explore the effect of ferroelectric polarization of electron-doped BaTiO3 (n-BaTiO3) on the spin-polarized transmission across the SrRuO3/n-BaTiO3(001) interface. Our study reveals that, in this system, the interface transmission is negatively spin polarized and that ferroelectric polarization reversal leads to a change in the transport spin polarization from -65% to -98%. Analytical model calculations demonstrate that this is a general effect for ferromagnetic-metal-ferroelectric-semiconductor systems and, furthermore, that ferroelectric modulation can even reverse the sign of spin polarization. The predicted effect provides a nonvolatile mechanism to electrically control spin injection in semiconductor-based spintronics devices.

  12. Electric control of spin injection into a ferroelectric semiconductor.

    PubMed

    Liu, Xiaohui; Burton, J D; Zhuravlev, M Ye; Tsymbal, Evgeny Y

    2015-01-30

    Electric-field control of spin-dependent properties has become one of the most attractive phenomena in modern materials research due to the promise of new device functionalities. One of the paradigms in this approach is to electrically toggle the spin polarization of carriers injected into a semiconductor using ferroelectric polarization as a control parameter. Using first-principles density-functional calculations, we explore the effect of ferroelectric polarization of electron-doped BaTiO3 (n-BaTiO3) on the spin-polarized transmission across the SrRuO3/n-BaTiO3(001) interface. Our study reveals that, in this system, the interface transmission is negatively spin polarized and that ferroelectric polarization reversal leads to a change in the transport spin polarization from -65% to -98%. Analytical model calculations demonstrate that this is a general effect for ferromagnetic-metal-ferroelectric-semiconductor systems and, furthermore, that ferroelectric modulation can even reverse the sign of spin polarization. The predicted effect provides a nonvolatile mechanism to electrically control spin injection in semiconductor-based spintronics devices. PMID:25679900

  13. Periodic attitude control of a slowly spinning spacecraft.

    NASA Technical Reports Server (NTRS)

    Todosiev, E. P.

    1973-01-01

    A periodic attitude control system is presented which permits control of secular errors of a slowly spinning spacecraft operating in a high disturbance environment. Attitude errors of the spin-axis are detected by sun sensors (or rate gyros) and are controlled by a periodic control law which modulates external control torques generated by mass expulsion torquers. Attitude stability during the uncontrolled periods is obtained passively via the vehicle spin momentum. Equations of motion, a system block diagram, and design parameters are presented for a typical spacecraft application. Simulation results are included which demonstrate the feasibility of the novel control concept. Salient features of the periodic control approach are implementation simplicity, excellent response, and a propellant utilization efficiency greater than 75 percent.

  14. Longitudinal spin separation of light and its performance in three-dimensionally controllable spin-dependent focal shift.

    PubMed

    Liu, Sheng; Li, Peng; Zhang, Yi; Gan, Xuetao; Wang, Meirong; Zhao, Jianlin

    2016-01-01

    Spin Hall effect of light, which is normally explored as a transverse spin-dependent separation of a light beam, has attracted enormous research interests. However, it seems there is no indication for the existence of the longitudinal spin separation of light. In this paper, we propose and experimentally realize the spin separation along the propagation direction by modulating the Pancharatnam-Berry (PB) phase. Due to the spin-dependent divergence and convergence determined by the PB phase, a focused Gaussian beam could split into two opposite spin states, and focuses at different distances, representing the longitudinal spin separation. By combining this longitudinal spin separation with the transverse one, we experimentally achieve the controllable spin-dependent focal shift in three dimensional space. This work provides new insight on steering the spin photons, and is expected to explore novel applications of optical trapping, manipulating, and micromachining with higher degree of freedom. PMID:26882995

  15. Longitudinal spin separation of light and its performance in three-dimensionally controllable spin-dependent focal shift

    PubMed Central

    Liu, Sheng; Li, Peng; Zhang, Yi; Gan, Xuetao; Wang, Meirong; Zhao, Jianlin

    2016-01-01

    Spin Hall effect of light, which is normally explored as a transverse spin-dependent separation of a light beam, has attracted enormous research interests. However, it seems there is no indication for the existence of the longitudinal spin separation of light. In this paper, we propose and experimentally realize the spin separation along the propagation direction by modulating the Pancharatnam-Berry (PB) phase. Due to the spin-dependent divergence and convergence determined by the PB phase, a focused Gaussian beam could split into two opposite spin states, and focuses at different distances, representing the longitudinal spin separation. By combining this longitudinal spin separation with the transverse one, we experimentally achieve the controllable spin-dependent focal shift in three dimensional space. This work provides new insight on steering the spin photons, and is expected to explore novel applications of optical trapping, manipulating, and micromachining with higher degree of freedom. PMID:26882995

  16. Spatiotemporally controlled single cell sonoporation

    PubMed Central

    Fan, Zhenzhen; Liu, Haiyan; Mayer, Michael; Deng, Cheri X.

    2012-01-01

    This paper presents unique approaches to enable control and quantification of ultrasound-mediated cell membrane disruption, or sonoporation, at the single-cell level. Ultrasound excitation of microbubbles that were targeted to the plasma membrane of HEK-293 cells generated spatially and temporally controlled membrane disruption with high repeatability. Using whole-cell patch clamp recording combined with fluorescence microscopy, we obtained time-resolved measurements of single-cell sonoporation and quantified the size and resealing rate of pores. We measured the intracellular diffusion coefficient of cytoplasmic RNA/DNA from sonoporation-induced transport of an intercalating fluorescent dye into and within single cells. We achieved spatiotemporally controlled delivery with subcellular precision and calcium signaling in targeted cells by selective excitation of microbubbles. Finally, we utilized sonoporation to deliver calcein, a membrane-impermeant substrate of multidrug resistance protein-1 (MRP1), into HEK-MRP1 cells, which overexpress MRP1, and monitored the calcein efflux by MRP1. This approach made it possible to measure the efflux rate in individual cells and to compare it directly to the efflux rate in parental control cells that do not express MRP1. PMID:23012425

  17. Single-Quantum Coherence Filter for Strongly Coupled Spin Systems for Localized 1H NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Trabesinger, Andreas H.; Mueller, D. Christoph; Boesiger, Peter

    2000-08-01

    A pulse sequence for localized in vivo1H NMR spectroscopy is presented, which selectively filters single-quantum coherence built up by strongly coupled spin systems. Uncoupled and weakly coupled spin systems do not contribute to the signal output. Analytical calculations using a product operator description of the strongly coupled AB spin system as well as in vitro tests demonstrate that the proposed filter produces a signal output for a strongly coupled AB spin system, whereas the resonances of a weakly coupled AX spin system and of uncoupled spins are widely suppressed. As a potential application, the detection of the strongly coupled AA‧BB‧ spin system of taurine at 1.5 T is discussed.

  18. Detection of single electron spin resonance in a double quantum dota)

    NASA Astrophysics Data System (ADS)

    Koppens, F. H. L.; Buizert, C.; Vink, I. T.; Nowack, K. C.; Meunier, T.; Kouwenhoven, L. P.; Vandersypen, L. M. K.

    2007-04-01

    Spin-dependent transport measurements through a double quantum dot are a valuable tool for detecting both the coherent evolution of the spin state of a single electron, as well as the hybridization of two-electron spin states. In this article, we discuss a model that describes the transport cycle in this regime, including the effects of an oscillating magnetic field (causing electron spin resonance) and the effective nuclear fields on the spin states in the two dots. We numerically calculate the current flow due to the induced spin flips via electron spin resonance, and we study the detector efficiency for a range of parameters. The experimental data are compared with the model and we find a reasonable agreement.

  19. Coherent Control of Collective Atomic Spins

    NASA Astrophysics Data System (ADS)

    Trail, Collin M.

    2011-12-01

    In this thesis I explore the use of collective spin angular momentum as a platform for quantum information processing. In the limit of a large number of atoms, the collective variables of atomic systems have a natural connection to the bosonic algebra of light (known as the Holstein-Primakoff or HP approximation) where components of the collective spin angular momentum effectively act as quadratures, making them natural systems for coupling to light. I have sought to improve previous schemes for the spin squeezing of atomic ensembles, such as the proposal of Takeuchi et. al. based on coherent quantum feedback [39]. In this scheme a beam of linearly polarized light passes through the atomic ensemble (prepared in a coherent state), coupling to the atoms through a state-dependent index of refraction (the Faraday effect). The light is then passed through a wave-plate and reflected back through the atoms for a second pass. This double-pass scheme leads to an effective nonlinearity as the atomic fluctuations are mapped onto the light on the first pass and then back on to the atoms in the second pass. The light acts as a bus coupling each atom to each of the others. This nonlinear interaction forms a shearing of the atomic coherent state that results in squeezing. The light is entangled to the atoms through these interactions, and remains entangled as it escapes the system. This leads to decoherence of the atoms as the light is lost to the environment, reducing the amount of spin squeezing achieved. The first step towards improving the double-pass scheme was to add a quantum eraser step in which the light is disentangled from the squeezed atoms. By first measuring one quadrature of the light, and then performing a measurement-dependent rotation on the atomic ensemble, it is possible to decouple the atoms and light so that the loss of the light does not reduce the atomic squeezing. This results in an improvement of the rate of atomic spin squeezing. A complete model

  20. Spin state of spin-crossover complexes: From single molecules to ultrathin films

    NASA Astrophysics Data System (ADS)

    Gruber, Manuel; Davesne, Vincent; Bowen, Martin; Boukari, Samy; Beaurepaire, Eric; Wulfhekel, Wulf; Miyamachi, Toshio

    2014-05-01

    The growth of spin-crossover Fe(1,10-phenanthroline)2(NCS)2 molecules on Cu(100) surfaces in the coverage range from 0.1 to 1.8 molecular layers was studied using a scanning tunneling microscope (STM) operated in ultrahigh vacuum at low temperature (≈4 K). STM imaging allowed us to extract the molecular adsorption geometry. While the first-layer molecules point their NCS groups toward the surface and their phenanthroline groups upwards, the adsorption geometry is reversed for the molecules in the second layer. For submonolayer coverages, a coexistence of molecules in the high- and low-spin states was found that is not correlated with the coverage. This coexistence is reduced for second-layer molecules, leading to a dominant spin state at low temperatures. Differential conductance spectra acquired at negative bias voltage on first- and second-layer molecules suggest that second-layer molecules are in the high-spin state and are partially electronically decoupled from the substrate. Furthermore, increasing the tip-to-sample voltage reduces the distance between the two lobes of the molecule. The current dependence of this effect suggests that a smooth spin crossover from a high- to a low-spin state occurs with increasing sample voltage. This analog spin-state switching is well described within a simple transition-state model involving modifications to the energy barriers between low- and high-spin states due to a tip-induced electric field through the Stark effect.

  1. High-sensitivity single NV magnetometry by spin-to-charge state mapping

    NASA Astrophysics Data System (ADS)

    Jaskula, Jean-Christophe; Shields, Brendan; Bauch, Erik; Lukin, Mikhail; Walsworth, Ronald; Trifonov, Alexei

    2015-05-01

    Nitrogen-Vacancy (NV) centers in diamond are atom-like quantum system in a solid state matrix whom its structure allows optical readout of the electronic spin. However, the optimal duration of optical readout is limited by a singlet state lifetime making single shot spin readout out of reach. On the other side, the NV center charge state readout can be extremely efficient (up to 99% fidelity) by using excitation at 594 nm. We will present a new method of spin readout utilizing a spin-depending photoionization process to map the electronic spin state of the NV onto the its charge state. Moreover, pre-selection on the charged state allows to minimize data acquisition time. This scheme improves single NV AC magnetometry by a factor of 5 and will benefit other single NV center experiments as well.

  2. Study of an Active Control System for a Spinning Body

    NASA Technical Reports Server (NTRS)

    Adams, J. J.

    1961-01-01

    The mission requirements for some satellites require that they spin continuously and at the same time maintain a precise direction of the spin axis. An analog-computer study has been made of an attitude control system which is suitable for such a satellite. The control system provides the necessary attitude control through the use of a spinning wheel, which will provide precession torques, commanded by an automatic closed-loop servomechanism system. The sensors used in the control loop are rate gyroscopes for damping of any wobble motion and a sun seeker for attitude control. The results of the study show that the controller can eliminate the wobble motion of the satellite resulting from a rectangular pulse moment disturbance and then return the spin axis to the reference space axis. The motion is damped to half amplitude in less than one cycle of the wobble motion. The controller can also reduce the motion resulting from a step change in product of inertia both by causing the new principal axis to be steadily alined with the spin vector and by reducing the cone angle generated by the reference body axis. These methods will reduce the motion whether the satellite is a disk, sphere, or rod configuration.

  3. Optical control of a spin switch in the weak spin-orbit coupling limit

    SciTech Connect

    Sola, Ignacio R.; Gonzalez-Vazquez, Jesus; Malinovsky, Vladimir S.

    2006-10-15

    A method to optically control a dark transition, for instance, the coupling between different spin states, is proposed. The control is achieved by manipulating the direction, amplitude, and duration of dynamic Stark shifts. Laser-driven spin switches can be prepared by conveniently generalizing different optical techniques, such as {pi}-pulse schemes and adiabatic passage schemes. The efficiency and robustness of the schemes is analyzed for both two-level and multilevel systems, implying quantum state selective wave packet transfer between states of different multiplicity.

  4. Quantum gates controlled by spin chain soliton excitations

    SciTech Connect

    Cuccoli, Alessandro; Nuzzi, Davide; Vaia, Ruggero; Verrucchi, Paola

    2014-05-07

    Propagation of soliton-like excitations along spin chains has been proposed as a possible way for transmitting both classical and quantum information between two distant parties with negligible dispersion and dissipation. In this work, a somewhat different use of solitons is considered. Solitons propagating along a spin chain realize an effective magnetic field, well localized in space and time, which can be exploited as a means to manipulate the state of an external spin (i.e., a qubit) that is weakly coupled to the chain. We have investigated different couplings between the qubit and the chain, as well as different soliton shapes, according to a Heisenberg chain model. It is found that symmetry properties strongly affect the effectiveness of the proposed scheme, and the most suitable setups for implementing single qubit quantum gates are singled out.

  5. Stars Can't Spin Out of Control (Artist's Animation)

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Click on the image for QuickTime Movie of Stars Can't Spin Out of Control

    This artist's animation demonstrates how a dusty planet-forming disk can slow down a whirling young star, essentially saving the star from spinning itself to death. Evidence for this phenomenon comes from NASA's Spitzer Space Telescope.

    The movie begins by showing a developing star (red ball). The star is basically a giant ball of gas that is collapsing onto itself. As it shrinks, it spins faster and faster, like a skater folding in his or her arms. The green lines represent magnetic fields.

    As gravity continues to pull matter inward, the star spins so fast, it starts to flatten out. The same principle applies to the planet Saturn, whose spin has caused it to be slightly squashed or oblate.

    A forming star can theoretically whip around fast enough to overcome gravity and flatten itself into a state where it can no longer become a full-fledged star. But stars don't spin out of control, possibly because swirling disks of dust slow them down. Such disks can be found orbiting young stars, and are filled with dust that might ultimately stick together to form planets.

    The second half of the animation demonstrates how a disk is thought to keep its star's speed in check. A developing star is shown twirling inside its disk. As it turns, its magnetic fields pass through the disk and get bogged down like a spoon in molasses. This locks the star's rotation to the slower-turning disk, so the star, while continuing to shrink, does not spin faster.

    Spitzer found evidence for star-slowing disks in a survey of nearly 500 forming stars in the Orion nebula. It observed that slowly spinning stars are five times more likely to host disks than rapidly spinning stars.

  6. Quantum Control nd Measurement of Spins in Cold Atomic Gases

    NASA Astrophysics Data System (ADS)

    Deutsch, Ivan

    2014-03-01

    Spins are natural carriers of quantum information given their long coherence time and our ability to precisely control and measure them with magneto-optical fields. Spins in cold atomic gases provide a pristine environment for such quantum control and measurement, and thus this system can act as a test-bed for the development of quantum simulators. I will discuss the progress my group has made in collaboration with Prof. Jessen, University of Arizona, to develop the toolbox for this test-bed. Through its interactions with rf and microwave magnetic fields, whose waveforms are designed through optimal control techniques, we can implement arbitrary unitary control on the internal hyperfine spins of cesium atoms, a 16 dimensional Hilbert space (isomorphic to 4 qubits). Control of the collective spin of the ensemble of many atoms is performed via the mutual coupling of the atomic ensemble to a mode of the electromagnetic field that acts as a quantum data bus for entangling atoms with one another. Internal spin control can be used to enhance the entangling power of the atom-photon interface. Finally, both projective and weak-continuous measurements can be performed to tomograhically reconstruct quantum states and processes.

  7. Probing Johnson noise and ballistic transport in normal metals with a single-spin qubit

    NASA Astrophysics Data System (ADS)

    Kolkowitz, S.; Safira, A.; High, A. A.; Devlin, R. C.; Choi, S.; Unterreithmeier, Q. P.; Patterson, D.; Zibrov, A. S.; Manucharyan, V. E.; Park, H.; Lukin, M. D.

    2015-03-01

    Thermally induced electrical currents, known as Johnson noise, cause fluctuating electric and magnetic fields in proximity to a conductor. These fluctuations are intrinsically related to the conductivity of the metal. We use single-spin qubits associated with nitrogen-vacancy centers in diamond to probe Johnson noise in the vicinity of conductive silver films. Measurements of polycrystalline silver films over a range of distances (20 to 200 nanometers) and temperatures (10 to 300 kelvin) are consistent with the classically expected behavior of the magnetic fluctuations. However, we find that Johnson noise is markedly suppressed next to single-crystal films, indicative of a substantial deviation from Ohm’s law at length scales below the electron mean free path. Our results are consistent with a generalized model that accounts for the ballistic motion of electrons in the metal, indicating that under the appropriate conditions, nearby electrodes may be used for controlling nanoscale optoelectronic, atomic, and solid-state quantum systems.

  8. Experimental limits on the fidelity of adiabatic geometric phase gates in a single solid-state spin qubit

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Nusran, N. M.; Slezak, B. R.; Gurudev Dutt, M. V.

    2016-05-01

    While it is often thought that the geometric phase is less sensitive to fluctuations in the control fields, a very general feature of adiabatic Hamiltonians is the unavoidable dynamic phase that accompanies the geometric phase. The effect of control field noise during adiabatic geometric quantum gate operations has not been probed experimentally, especially in the canonical spin qubit system that is of interest for quantum information. We present measurement of the Berry phase and carry out adiabatic geometric phase gate in a single solid-state spin qubit associated with the nitrogen-vacancy center in diamond. We manipulate the spin qubit geometrically by careful application of microwave radiation that creates an effective rotating magnetic field, and observe the resulting Berry phase signal via spin echo interferometry. Our results show that control field noise at frequencies higher than the spin echo clock frequency causes decay of the quantum phase, and degrades the fidelity of the geometric phase gate to the classical threshold after a few (∼10) operations. This occurs inspite of the geometric nature of the state preparation, due to unavoidable dynamic contributions. We have carried out systematic analysis and numerical simulations to study the effects of the control field noise and imperfect driving waveforms on the quantum phase gate.

  9. Twist-3 spin observables for single-hadron production in DIS

    SciTech Connect

    Gamberg, Leonard P.; Kanazawa, Koichi; Kang, Zhong-Bo; Metz, Andreas; Pitonyak, Daniel A.; Prokudin, Alexei; Schlegel, Marc

    2015-09-01

    Recently, three twist-3 spin asymmetries for single-inclusive hadron production in deep-inelastic lepton-nucleon scattering have been computed using collinear factorization and the leading order approximation. Here we summarize the main findings of these studies.

  10. Magnetization dynamics in the presence of pure spin currents in magnetic single and double layers in spin ballistic and diffusive regimes.

    SciTech Connect

    Mosendz, O.; Woltersdorf, G.; Kardasz, B.; Heinrich, B.; Back, C. H.; Materials Science Division; Univ. Regensburg; Simon Fraser Univ.

    2009-01-01

    In this paper we study the spin transport by using the spin-pumping effect in epitaxial magnetic single and double layer film structures. For the magnetic single layer sample we show the spin-pumping-induced interface damping increases and saturates with the Au capping layer thickness. In addition magnetic double layer structures allowed us to investigate both the spin-pump and spin-sink effects. Coupling of pure spin currents to the magnetization via spin-sink effect is studied using time-resolved magneto-optical Kerr effect. These measurements were used to study the propagation of pure spin currents across a Au spacer layer between the two ferromagnets. The propagation of spin momentum density through the Au spacer layer was well described by spin-diffusion equation, which takes into account electron momentum and spin-flip scattering. The spin-diffusion theory was integrated into modified Landau-Lifshitz equations accounting in self-consistent manner for spin-pump/sink mechanism and spin momentum density propagation. Good agreement between theory and experimental data was found.

  11. 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.

  12. Metal-center exchange of tetrahedral cages: single crystal to single crystal and spin-crossover properties.

    PubMed

    Zhang, Feng-Li; Chen, Jia-Qian; Qin, Long-Fang; Tian, Lei; Li, Zaijun; Ren, Xuehong; Gu, Zhi-Guo

    2016-04-01

    An effective single crystal to single crystal transformation from a tetrahedral Ni cage to an FeNi cage was demonstrated. The iron(ii) centers of the FeNi cage can be induced to display spin crossover behaviors with an increasing amount of Fe(II) ions. The SCSC metal-center exchange provides a powerful approach to modify solid magnetic properties.

  13. Electron spin control of optically levitated nanodiamonds in vacuum

    PubMed Central

    Hoang, Thai M.; Ahn, Jonghoon; Bang, Jaehoon; Li, Tongcang

    2016-01-01

    Electron spins of diamond nitrogen-vacancy (NV) centres are important quantum resources for nanoscale sensing and quantum information. Combining NV spins with levitated optomechanical resonators will provide a hybrid quantum system for novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centres in low vacuum. We observe that the strength of electron spin resonance (ESR) is enhanced when the air pressure is reduced. To better understand this system, we investigate the effects of trap power and measure the absolute internal temperature of levitated nanodiamonds with ESR after calibration of the strain effect. We also observe that oxygen and helium gases have different effects on both the photoluminescence and the ESR contrast of nanodiamond NV centres, indicating potential applications of NV centres in oxygen gas sensing. Our results pave the way towards a levitated spin–optomechanical system for studying macroscopic quantum mechanics. PMID:27432560

  14. Transverse Single Spin and Azimuthal Asymmetries in Hadronic Collisions at STAR

    NASA Astrophysics Data System (ADS)

    Vossen, Anselm

    2015-01-01

    Hadronic collisions with transversely polarized protons are an important part of the quest to understand the transverse spin structure of the proton. Experiments at RHIC collected large datasets at center of mass energies of 200 GeV and 500 GeV, accessing a kinematic regime where factorization is expected to hold. The STAR detector at RHIC, due to its azimuthal symmetry, particle identification capabilities and large acceptance compared with other experiments with polarized protons, is in a unique position to study transverse spin phenomena in p + p↑. This contribution will highlight measurements of transversity using di-hadron correlations, transverse single spin asymmetries in jets, measurements sensitive to the origins of the large single spin asymmetries measured in the forward direction, transverse spin asymmetries in W production, which are sensitive to modified universality effects of Sivers function as well as short and long-term upgrades at STAR.

  15. Highly efficient spin polarizer based on individual heterometallic cubane single-molecule magnets

    NASA Astrophysics Data System (ADS)

    Dong, Damin

    2015-09-01

    The spin-polarized transport across a single-molecule magnet [Mn3Zn(hmp)3O(N3)3(C3H5O2)3].2CHCl3 has been investigated using a density functional theory combined with Keldysh non-equilibrium Green's function formalism. It is shown that this single-molecule magnet has perfect spin filter behaviour. By adsorbing Ni3 cluster onto non-magnetic Au electrode, a large magnetoresistance exceeding 172% is found displaying molecular spin valve feature. Due to the tunneling via discrete quantum-mechanical states, the I-V curve has a stepwise character and negative differential resistance behaviour.

  16. Temperature induced Spin Switching in SmFeO3 Single Crystal

    PubMed Central

    Cao, Shixun; Zhao, Huazhi; Kang, Baojuan; Zhang, Jincang; Ren, Wei

    2014-01-01

    The prospect of controlling the magnetization (M) of a material is of great importance from the viewpoints of fundamental physics and future applications of emerging spintronics. A class of rare-earth orthoferrites RFeO3 (R is rare-earth element) materials exhibit striking physical properties of spin switching and magnetization reversal induced by temperature and/or applied magnetic field. Furthermore, due to the novel magnetic, magneto-optic and multiferroic properties etc., RFeO3 materials are attracting more and more interests in recent years. We have prepared and investigated a prototype of RFeO3 materials, namely SmFeO3 single-crystal. And we report magnetic measurements upon both field cooling (FC) and zero-field cooling (ZFC) of the sample, as a function of temperature and applied magnetic field. The central findings of this study include that the magnetization of single-crystal SmFeO3 can be switched by temperature, and tuning the magnitude of applied magnetic field allows us to realize such spin switching even at room temperature. PMID:25091202

  17. Quantum Router for Single Photons Carrying Spin and Orbital Angular Momentum

    NASA Astrophysics Data System (ADS)

    Chen, Yuanyuan; Jiang, Dong; Xie, Ling; Chen, Lijun

    2016-06-01

    Quantum router is an essential element in the quantum network. Here, we present a fully quantum router based on interaction free measurement and quantum dots. The signal photonic qubit can be routed to different output ports according to one control electronic qubit. Besides, our scheme is an interferometric method capable of routing single photons carrying either spin angular momentum (SAM) or orbital angular momentum (OAM), or simultaneously carrying SAM and OAM. Then we describe a cascaded multi-level quantum router to construct a one-to-many quantum router. Subsequently we analyze the success probability by using a tunable controlled phase gate. The implementation issues are also discussed to show that this scheme is feasible.

  18. Quantum Router for Single Photons Carrying Spin and Orbital Angular Momentum

    PubMed Central

    Chen, Yuanyuan; Jiang, Dong; Xie, Ling; Chen, Lijun

    2016-01-01

    Quantum router is an essential element in the quantum network. Here, we present a fully quantum router based on interaction free measurement and quantum dots. The signal photonic qubit can be routed to different output ports according to one control electronic qubit. Besides, our scheme is an interferometric method capable of routing single photons carrying either spin angular momentum (SAM) or orbital angular momentum (OAM), or simultaneously carrying SAM and OAM. Then we describe a cascaded multi-level quantum router to construct a one-to-many quantum router. Subsequently we analyze the success probability by using a tunable controlled phase gate. The implementation issues are also discussed to show that this scheme is feasible. PMID:27256772

  19. Quantum Router for Single Photons Carrying Spin and Orbital Angular Momentum.

    PubMed

    Chen, Yuanyuan; Jiang, Dong; Xie, Ling; Chen, Lijun

    2016-06-03

    Quantum router is an essential element in the quantum network. Here, we present a fully quantum router based on interaction free measurement and quantum dots. The signal photonic qubit can be routed to different output ports according to one control electronic qubit. Besides, our scheme is an interferometric method capable of routing single photons carrying either spin angular momentum (SAM) or orbital angular momentum (OAM), or simultaneously carrying SAM and OAM. Then we describe a cascaded multi-level quantum router to construct a one-to-many quantum router. Subsequently we analyze the success probability by using a tunable controlled phase gate. The implementation issues are also discussed to show that this scheme is feasible.

  20. Control of Propagating Spin Waves via Spin Transfer Torque in a Metallic Bilayer Waveguide

    NASA Astrophysics Data System (ADS)

    An, Kyongmo; Birt, Daniel; Pai, Chi-Feng; Olsson, Kevin; Ralph, Daniel; Buhrman, Robert; Li, Xiaoqin

    2014-03-01

    We investigate the effect of a direct current on propagating spin waves in a CoFeB/Ta bilayer structure. Using the micro-Brillouin light scattering technique, we observe that the spin wave amplitude may be attenuated or amplified depending on the direction of the current and the applied magnetic field. Our work suggests an effective approach for electrically controlling the propagation of spin waves in a magnetic waveguide and may be useful in a number of applications such as phase locked nano-oscillators and hybrid information processing devices. AFOSR FA9550-08-1-0463, AFOSR FA-9550-08-1-0058 and the NSF-IGERT program via grant DGE-0549417.

  1. Spin transport in tantalum studied using magnetic single and double layers

    NASA Astrophysics Data System (ADS)

    Montoya, Eric; Omelchenko, Pavlo; Coutts, Chris; Lee-Hone, Nicholas R.; Hübner, René; Broun, David; Heinrich, Bret; Girt, Erol

    2016-08-01

    We report on spin transport in sputter-grown Ta films measured by ferromagnetic resonance. Spin diffusion length and spin mixing conductance are determined from magnetic damping measurements for a varying thickness of Ta layer 0 ≤dTa≤10 nm. The different boundary conditions of single- and double-magnetic-layer heterostructures Py |Ta and Py |Ta | [Py |Fe ] allow us to significantly narrow down the parameter space and test various models. We show that a common approach of using bulk resistivity value in the analysis yields inconsistent spin diffusion length and spin mixing conductance values for magnetic single- and double-layer structures. X-ray diffraction shows that bulk Ta is a combination of β -Ta and bcc-Ta . However, in the region of significant spin transport, ≲2 nm, there is an intermediate region of growth where the Ta lacks long-range structural order, as observed by transmission electron microscopy. Thickness-dependent resistivity measurements confirm that the bulk and intermediate regions have significantly different resistivity values. We find that the data can be well represented if the intermediate region resistivity value is used in the analysis. Additionally, the data can be fit if resistivity has the measured thickness dependence and spin diffusion length is restricted to be inversely proportional to resistivity. Finally, we rule out a model in which spin diffusion length is a constant, while the resistivity has the measured thickness dependence.

  2. Controlling spin polarization of a quantum dot via a helical edge state

    NASA Astrophysics Data System (ADS)

    Probst, Benedikt; Virtanen, Pauli; Recher, Patrik

    2015-07-01

    We investigate a Zeeman-split quantum dot (QD) containing a single spin 1 /2 weakly coupled to a helical Luttinger liquid (HLL) within a generalized master equation approach. The HLL induces a tunable magnetization direction on the QD controlled by an applied bias voltage when the quantization axes of the QD and the HLL are noncollinear. The backscattering conductance (BSC) in the HLL is finite and shows a resonance feature when the bias voltage equals the Zeeman energy in magnitude. The observed BSC asymmetry in bias voltage directly reflects the quantization axis of the HLL spin.

  3. Spin-orbit torque magnetization switching controlled by geometry.

    PubMed

    Safeer, C K; Jué, Emilie; Lopez, Alexandre; Buda-Prejbeanu, Liliana; Auffret, Stéphane; Pizzini, Stefania; Boulle, Olivier; Miron, Ioan Mihai; Gaudin, Gilles

    2016-02-01

    Magnetization reversal by an electric current is essential for future magnetic data storage technology, such as magnetic random access memories. Typically, an electric current is injected into a pillar-shaped magnetic element, and switching relies on the transfer of spin momentum from a ferromagnetic reference layer (an approach known as spin-transfer torque). Recently, an alternative technique has emerged that uses spin-orbit torque (SOT) and allows the magnetization to be reversed without a polarizing layer by transferring angular momentum directly from the crystal lattice. With spin-orbit torque, the current is no longer applied perpendicularly, but is in the plane of the magnetic thin film. Therefore, the current flow is no longer restricted to a single direction and can have any orientation within the film plane. Here, we use Kerr microscopy to examine spin-orbit torque-driven domain wall motion in Co/AlOx wires with different shapes and orientations on top of a current-carrying Pt layer. The displacement of the domain walls is found to be highly dependent on the angle between the direction of the current and domain wall motion, and asymmetric and nonlinear with respect to the current polarity. Using these insights, devices are fabricated in which magnetization switching is determined entirely by the geometry of the device. PMID:26551017

  4. Spin-orbit torque magnetization switching controlled by geometry

    NASA Astrophysics Data System (ADS)

    Safeer, C. K.; Jué, Emilie; Lopez, Alexandre; Buda-Prejbeanu, Liliana; Auffret, Stéphane; Pizzini, Stefania; Boulle, Olivier; Miron, Ioan Mihai; Gaudin, Gilles

    2016-02-01

    Magnetization reversal by an electric current is essential for future magnetic data storage technology, such as magnetic random access memories. Typically, an electric current is injected into a pillar-shaped magnetic element, and switching relies on the transfer of spin momentum from a ferromagnetic reference layer (an approach known as spin-transfer torque). Recently, an alternative technique has emerged that uses spin-orbit torque (SOT) and allows the magnetization to be reversed without a polarizing layer by transferring angular momentum directly from the crystal lattice. With spin-orbit torque, the current is no longer applied perpendicularly, but is in the plane of the magnetic thin film. Therefore, the current flow is no longer restricted to a single direction and can have any orientation within the film plane. Here, we use Kerr microscopy to examine spin-orbit torque-driven domain wall motion in Co/AlOx wires with different shapes and orientations on top of a current-carrying Pt layer. The displacement of the domain walls is found to be highly dependent on the angle between the direction of the current and domain wall motion, and asymmetric and nonlinear with respect to the current polarity. Using these insights, devices are fabricated in which magnetization switching is determined entirely by the geometry of the device.

  5. Photonic spin-controlled multifunctional shared-aperture antenna array

    NASA Astrophysics Data System (ADS)

    Maguid, Elhanan; Yulevich, Igor; Veksler, Dekel; Kleiner, Vladimir; Brongersma, Mark L.; Hasman, Erez

    2016-06-01

    The shared-aperture phased antenna array developed in the field of radar applications is a promising approach for increased functionality in photonics. The alliance between the shared-aperture concepts and the geometric phase phenomenon arising from spin-orbit interaction provides a route to implement photonic spin-control multifunctional metasurfaces. We adopted a thinning technique within the shared-aperture synthesis and investigated interleaved sparse nanoantenna matrices and the spin-enabled asymmetric harmonic response to achieve helicity-controlled multiple structured wavefronts such as vortex beams carrying orbital angular momentum. We used multiplexed geometric phase profiles to simultaneously measure spectrum characteristics and the polarization state of light, enabling integrated on-chip spectropolarimetric analysis. The shared-aperture metasurface platform opens a pathway to novel types of nanophotonic functionality.

  6. Photonic spin-controlled multifunctional shared-aperture antenna array.

    PubMed

    Maguid, Elhanan; Yulevich, Igor; Veksler, Dekel; Kleiner, Vladimir; Brongersma, Mark L; Hasman, Erez

    2016-06-01

    The shared-aperture phased antenna array developed in the field of radar applications is a promising approach for increased functionality in photonics. The alliance between the shared-aperture concepts and the geometric phase phenomenon arising from spin-orbit interaction provides a route to implement photonic spin-control multifunctional metasurfaces. We adopted a thinning technique within the shared-aperture synthesis and investigated interleaved sparse nanoantenna matrices and the spin-enabled asymmetric harmonic response to achieve helicity-controlled multiple structured wavefronts such as vortex beams carrying orbital angular momentum. We used multiplexed geometric phase profiles to simultaneously measure spectrum characteristics and the polarization state of light, enabling integrated on-chip spectropolarimetric analysis. The shared-aperture metasurface platform opens a pathway to novel types of nanophotonic functionality. PMID:27103668

  7. Absence of a spin-signature from a single Ho adatom as probed by spin-sensitive tunneling

    PubMed Central

    Steinbrecher, M.; Sonntag, A.; Dias, M. dos Santos; Bouhassoune, M.; Lounis, S.; Wiebe, J.; Wiesendanger, R.; Khajetoorians, A. A.

    2016-01-01

    Whether rare-earth materials can be used as single-atom magnetic memory is an ongoing debate in recent literature. Here we show, by inelastic and spin-resolved scanning tunnelling-based methods, that we observe a strong magnetic signal and excitation from Fe atoms adsorbed on Pt(111), but see no signatures of magnetic excitation or spin-based telegraph noise for Ho atoms. Moreover, we observe that the indirect exchange field produced by a single Ho atom is negligible, as sensed by nearby Fe atoms. We demonstrate, using ab initio methods, that this stems from a comparatively weak coupling of the Ho 4f electrons with both tunnelling electrons and substrate-derived itinerant electrons, making both magnetic coupling and detection very difficult when compared to 3d elements. We discuss these results in the context of ongoing disputes and clarify important controversies. PMID:26838811

  8. Absence of a spin-signature from a single Ho adatom as probed by spin-sensitive tunneling.

    PubMed

    Steinbrecher, M; Sonntag, A; dos Santos Dias, M; Bouhassoune, M; Lounis, S; Wiebe, J; Wiesendanger, R; Khajetoorians, A A

    2016-01-01

    Whether rare-earth materials can be used as single-atom magnetic memory is an ongoing debate in recent literature. Here we show, by inelastic and spin-resolved scanning tunnelling-based methods, that we observe a strong magnetic signal and excitation from Fe atoms adsorbed on Pt(111), but see no signatures of magnetic excitation or spin-based telegraph noise for Ho atoms. Moreover, we observe that the indirect exchange field produced by a single Ho atom is negligible, as sensed by nearby Fe atoms. We demonstrate, using ab initio methods, that this stems from a comparatively weak coupling of the Ho 4f electrons with both tunnelling electrons and substrate-derived itinerant electrons, making both magnetic coupling and detection very difficult when compared to 3d elements. We discuss these results in the context of ongoing disputes and clarify important controversies. PMID:26838811

  9. Absence of a spin-signature from a single Ho adatom as probed by spin-sensitive tunneling

    NASA Astrophysics Data System (ADS)

    Steinbrecher, M.; Sonntag, A.; Dias, M. Dos Santos; Bouhassoune, M.; Lounis, S.; Wiebe, J.; Wiesendanger, R.; Khajetoorians, A. A.

    2016-02-01

    Whether rare-earth materials can be used as single-atom magnetic memory is an ongoing debate in recent literature. Here we show, by inelastic and spin-resolved scanning tunnelling-based methods, that we observe a strong magnetic signal and excitation from Fe atoms adsorbed on Pt(111), but see no signatures of magnetic excitation or spin-based telegraph noise for Ho atoms. Moreover, we observe that the indirect exchange field produced by a single Ho atom is negligible, as sensed by nearby Fe atoms. We demonstrate, using ab initio methods, that this stems from a comparatively weak coupling of the Ho 4f electrons with both tunnelling electrons and substrate-derived itinerant electrons, making both magnetic coupling and detection very difficult when compared to 3d elements. We discuss these results in the context of ongoing disputes and clarify important controversies.

  10. Spin splitting anisotropy in single diluted magnetic nanowire heterostructures.

    PubMed

    Szymura, Małgorzata; Wojnar, Piotr; Kłopotowski, Łukasz; Suffczyński, Jan; Goryca, Mateusz; Smoleński, Tomasz; Kossacki, Piotr; Zaleszczyk, Wojciech; Wojciechowski, Tomasz; Karczewski, Grzegorz; Wojtowicz, Tomasz; Kossut, Jacek

    2015-03-11

    We study the impact of the nanowire shape anisotropy on the spin splitting of excitonic photoluminescence. The experiments are performed on individual ZnMnTe/ZnMgTe core/shell nanowires as well as on ZnTe/ZnMgTe core/shell nanowires containing optically active magnetic CdMnTe insertions. When the magnetic field is oriented parallel to the nanowire axis, the spin splitting is several times larger than for the perpendicular field. We interpret this pronounced anisotropy as an effect of mixing of valence band states arising from the strain present in the core/shell geometry. This interpretation is further supported by theoretical calculations which allow to reproduce experimental results.

  11. Entangling spin-spin interactions of ions in individually controlled potential wells

    NASA Astrophysics Data System (ADS)

    Wilson, Andrew; Colombe, Yves; Brown, Kenton; Knill, Emanuel; Leibfried, Dietrich; Wineland, David

    2014-03-01

    Physical systems that cannot be modeled with classical computers appear in many different branches of science, including condensed-matter physics, statistical mechanics, high-energy physics, atomic physics and quantum chemistry. Despite impressive progress on the control and manipulation of various quantum systems, implementation of scalable devices for quantum simulation remains a formidable challenge. As one approach to scalability in simulation, here we demonstrate an elementary building-block of a configurable quantum simulator based on atomic ions. Two ions are trapped in separate potential wells that can individually be tailored to emulate a number of different spin-spin couplings mediated by the ions' Coulomb interaction together with classical laser and microwave fields. We demonstrate deterministic tuning of this interaction by independent control of the local wells and emulate a particular spin-spin interaction to entangle the internal states of the two ions with 0.81(2) fidelity. Extension of the building-block demonstrated here to a 2D-network, which ion-trap micro-fabrication processes enable, may provide a new quantum simulator architecture with broad flexibility in designing and scaling the arrangement of ions and their mutual interactions. This research was funded by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA), ONR, and the NIST Quantum Information Program.

  12. Enhanced Spin Squeezing Through Quantum Control of Qudits

    NASA Astrophysics Data System (ADS)

    Norris, Leigh; Trail, Collin; Deutsch, Ivan; Jessen, Poul

    2012-10-01

    Spin squeezed states have applications in metrology and quantum information processing. Most spin squeezing research to date has focused on ensembles of qubit spins. We explore squeezed state production in an ensemble of spin f>1/2 alkali atoms (qudits). Collective interactions are achieved through coherent quantum feedback of a laser probe, interacting with the ensemble through Faraday interaction. This process is enhanced with control of the atomic qudits, both before and after the collective interaction. Initial preparation increases the collective squeezing parameter through enhancement of resolvable quantum fluctuations, but comes at the price of increased decoherence. We find an optimal state preparation, achieving an increased squeezing parameter while remaining robust to decoherence. After the collective interaction, qudit control maps generated entanglement to different pseudo-spin subspaces where it is metrologically useful, e.g., the clock transition or the stretched state for magnetometry. These considerations highlight the unique capabilities of our platform: we can transfer correlations between subspaces to explore a wider variety of nonclassical states, with ultimate application in sensors or quantum information processors.

  13. Enhanced Spin Squeezing Through Quantum Control of Qudits

    NASA Astrophysics Data System (ADS)

    Norris, Leigh; Trail, Collin; Jessen, Poul; Deutsch, Ivan

    2012-06-01

    Spin squeezed states have applications in metrology and quantum information processing. Most spin squeezing research to date has focused on ensembles of qubit spins. We explore squeezed state production in an ensemble of spin f>1/2 alkali atoms (qudits). Collective interactions are achieved through coherent quantum feedback of a laser probe, interacting with the ensemble through Faraday interaction. This process is enhanced with control of the atomic qudits, both before and after the collective interaction. Initial preparation increases the collective squeezing parameter through enhancement of resolvable quantum fluctuations, but comes at the price of increased decoherence. We find an optimal state preparation, achieving an increased squeezing parameter while remaining robust to decoherence. After the collective interaction, qudit control maps generated entanglement to different pseudo-spin subspaces where it is metrologically useful, e.g., the clock transition or the stretched state for magnetometry. These considerations highlight the unique capabilities of our platform: we can transfer correlations between subspaces to explore a wider variety of nonclassical states, with ultimate application in sensors or quantum information processors.

  14. Spin-orbit coupling and the static polarizability of single-wall carbon nanotubes

    SciTech Connect

    Diniz, Ginetom S. Ulloa, Sergio E.

    2014-07-14

    We calculate the static longitudinal polarizability of single-wall carbon tubes in the long wavelength limit taking into account spin-orbit effects. We use a four-orbital orthogonal tight-binding formalism to describe the electronic states and the random phase approximation to calculate the dielectric function. We study the role of both the Rashba as well as the intrinsic spin-orbit interactions on the longitudinal dielectric response, i.e., when the probing electric field is parallel to the nanotube axis. The spin-orbit interaction modifies the nanotube electronic band dispersions, which may especially result in a small gap opening in otherwise metallic tubes. The bandgap size and state features, the result of competition between Rashba and intrinsic spin-orbit interactions, result in drastic changes in the longitudinal static polarizability of the system. We discuss results for different nanotube types and the dependence on nanotube radius and spin-orbit couplings.

  15. Fluorescence thermometry enhanced by the quantum coherence of single spins in diamond

    PubMed Central

    Toyli, David M.; de las Casas, Charles F.; Christle, David J.; Dobrovitski, Viatcheslav V.; Awschalom, David D.

    2013-01-01

    We demonstrate fluorescence thermometry techniques with sensitivities approaching 10 mK⋅Hz−1/2 based on the spin-dependent photoluminescence of nitrogen vacancy (NV) centers in diamond. These techniques use dynamical decoupling protocols to convert thermally induced shifts in the NV center's spin resonance frequencies into large changes in its fluorescence. By mitigating interactions with nearby nuclear spins and facilitating selective thermal measurements, these protocols enhance the spin coherence times accessible for thermometry by 45-fold, corresponding to a 7-fold improvement in the NV center’s temperature sensitivity. Moreover, we demonstrate these techniques can be applied over a broad temperature range and in both finite and near-zero magnetic field environments. This versatility suggests that the quantum coherence of single spins could be practically leveraged for sensitive thermometry in a wide variety of biological and microscale systems. PMID:23650364

  16. Spin-orbit coupling and the static polarizability of single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Diniz, Ginetom S.; Ulloa, Sergio E.

    2014-07-01

    We calculate the static longitudinal polarizability of single-wall carbon tubes in the long wavelength limit taking into account spin-orbit effects. We use a four-orbital orthogonal tight-binding formalism to describe the electronic states and the random phase approximation to calculate the dielectric function. We study the role of both the Rashba as well as the intrinsic spin-orbit interactions on the longitudinal dielectric response, i.e., when the probing electric field is parallel to the nanotube axis. The spin-orbit interaction modifies the nanotube electronic band dispersions, which may especially result in a small gap opening in otherwise metallic tubes. The bandgap size and state features, the result of competition between Rashba and intrinsic spin-orbit interactions, result in drastic changes in the longitudinal static polarizability of the system. We discuss results for different nanotube types and the dependence on nanotube radius and spin-orbit couplings.

  17. Spin reorientation transition process in single crystal NdFeO3

    NASA Astrophysics Data System (ADS)

    Song, Gaibei; Jiang, Junjie; Kang, Baojuan; Zhang, Jincang; Cheng, Zhenxiang; Ma, Guohong; Cao, Shixun

    2015-06-01

    The spin reorientation transition in single crystal NdFeO3 is studied using AC magnetic susceptibility, hysteresis loops, and polarized terahertz (THz) time domain spectroscopy measurements. Different frequency dependence behaviors of AC susceptibility reflect that the dynamic response of magnetization inside the spin reorientation region differs from the phase outside the transition region. The magnetization hysteresis loops at different temperatures reveal that domains formed during the spin reorientation process, which coincides with the abrupt increase of AC magnetic susceptibility during the transition. In addition, temperature dependent THz wave excitation of quasi-antiferromagnetic mode indicates the process of spin reorientation as a continuous rotation of Fe3+ spins rather than a mixed phase of Γ4 and Γ2.

  18. Magnetoresistance effect of heat generation in a single-molecular spin-valve

    NASA Astrophysics Data System (ADS)

    Jiang, Feng; Yan, Yonghong; Wang, Shikuan; Yan, Yijing

    2016-02-01

    Based on non-equilibrium Green's functions' theory and small polaron transformation's technology, we study the heat generation by current through a single-molecular spin-valve. Numerical results indicate that the variation of spin polarization degree can change heat generation effectively, the spin-valve effect happens not only in electrical current but also in heat generation when Coulomb repulsion in quantum dot is smaller than phonon frequency and interestingly, when Coulomb repulsion is larger than phonon frequency, the inverse spin-valve effect appears by sweeping gate voltage and is enlarged with bias increasing. The inverse spin-valve effect will induce the unique heat magnetoresistance effect, which can be modulated from heat-resistance to heat-gain by gate voltage easily.

  19. Control of spinning flexible spacecraft by modal synthesis

    NASA Technical Reports Server (NTRS)

    Meirovitch, L.; Vanlandingham, H. F.; Oez, H.

    1976-01-01

    A procedure is presented for the active control of a spinning flexible spacecraft. Such a system exhibits gyroscopic effects. The design of the controller is based on modal decomposition of the gyroscopic system. This modal decoupling procedure leads to a control mechanism implemented in modular form, which represents a distinct computational advantage over the control of the coupled system. Design procedures are demonstrated for two types of control algorithms, linear and nonlinear. The first represents classical linear feedback approach, and the second represents an application of on-off control, both types made feasible by the modal decomposition scheme.

  20. Quantum Stirling heat engine and refrigerator with single and coupled spin systems

    NASA Astrophysics Data System (ADS)

    Huang, Xiao-Li; Niu, Xin-Ya; Xiu, Xiao-Ming; Yi, Xue-Xi

    2014-02-01

    We study the reversible quantum Stirling cycle with a single spin or two coupled spins as the working substance. With the single spin as the working substance, we find that under certain conditions the reversed cycle of a heat engine is NOT a refrigerator, this feature holds true for a Stirling heat engine with an ion trapped in a shallow potential as its working substance. The efficiency of quantum Stirling heat engine can be higher than the efficiency of the Carnot engine, but the performance coefficient of the quantum Stirling refrigerator is always lower than its classical counterpart. With two coupled spins as the working substance, we find that a heat engine can turn to a refrigerator due to the increasing of the coupling constant, this can be explained by the properties of the isothermal line in the magnetic field-entropy plane.

  1. Recent Results of Target Single-Spin Asymmetry Experiments at Jefferson Lab

    SciTech Connect

    Jiang, Xiaodong

    2013-08-01

    We report recent results from Jefferson Lab Hall A “Neutron Transversity” experiment (E06-010). Transversely polarized target single-spin asymmetry AUT and beam-target double-spin asymmetry A{sub LT} have been measured in semi-inclusive deep-inelastic scattering (SIDIS) reactions on a polarized neutron ({sup 3}He) target. Collins-type and Sivers-type asymmetries have been extracted from A{sub UT} for charged pion SIDIS productions, which are sensitive to quark transversity and Sivers distributions, correspondingly. Double spin asymmetry A{sub LT} is sensitive to a specific quark transverse momentum dependent parton distribution (TMD), the so-called “ transverse helicity” (g{sub 1T} ) distributions. In addition, target single-spin asymmetries A{sub y} in inclusive electron scattering on a transversely polarized {sup 3}He target in quasi-elastic and deep inelastic kinematics were also measured in Hall A.

  2. Nanoscale control of low-dimensional spin structures in manganites

    NASA Astrophysics Data System (ADS)

    Jing, Wang; Iftikhar, Ahmed Malik; Renrong, Liang; Wen, Huang; Renkui, Zheng; Jinxing, Zhang

    2016-06-01

    Due to the upcoming demands of next-generation electronic/magnetoelectronic devices with low-energy consumption, emerging correlated materials (such as superconductors, topological insulators and manganites) are one of the highly promising candidates for the applications. For the past decades, manganites have attracted great interest due to the colossal magnetoresistance effect, charge-spin-orbital ordering, and electronic phase separation. However, the incapable of deterministic control of those emerging low-dimensional spin structures at ambient condition restrict their possible applications. Therefore, the understanding and control of the dynamic behaviors of spin order parameters at nanoscale in manganites under external stimuli with low energy consumption, especially at room temperature is highly desired. In this review, we collected recent major progresses of nanoscale control of spin structures in manganites at low dimension, especially focusing on the control of their phase boundaries, domain walls as well as the topological spin structures (e.g., skyrmions). In addition, capacitor-based prototype spintronic devices are proposed by taking advantage of the above control methods in manganites. This capacitor-based structure may provide a new platform for the design of future spintronic devices with low-energy consumption. Project supported by the National Basic Research Program of China (Grant No. 2014CB920902), the National Natural Science Foundation of China (Grant Nos. 61306105 and 51572278), the Information Science and Technology (TNList) Cross-discipline Foundation from Tsinghua National Laboratory, China and the Fund from the State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China.

  3. Tunneling anisotropic magnetoresistance: a spin-valve-like tunnel magnetoresistance using a single magnetic layer.

    PubMed

    Gould, C; Rüster, C; Jungwirth, T; Girgis, E; Schott, G M; Giraud, R; Brunner, K; Schmidt, G; Molenkamp, L W

    2004-09-10

    We introduce a new class of spintronic devices in which a spin-valve-like effect results from strong spin-orbit coupling in a single ferromagnetic layer rather than from injection and detection of a spin-polarized current by two coupled ferromagnets. The effect is observed in a normal-metal-insulator-ferromagnetic-semiconductor tunneling device. This behavior is caused by the interplay of the anisotropic density of states in (Ga,Mn)As with respect to the magnetization direction and the two-step magnetization reversal process in this material. PMID:15447375

  4. Bimodal Latex Effect on Spin-Coated Thin Conductive Polymer-Single-Walled Carbon Nanotube Layers.

    PubMed

    Moradi, Mohammad-Amin; Larrakoetxea Angoitia, Katalin; van Berkel, Stefan; Gnanasekaran, Karthikeyan; Friedrich, Heiner; Heuts, Johan P A; van der Schoot, Paul; van Herk, Alex M

    2015-11-10

    We synthesize two differently sized poly(methyl methacrylate-co-tert-butyl acrylate) latexes by emulsion polymerization and mix these with a sonicated single-walled carbon nanotube (SWCNT) dispersion, in order to prepare 3% SWCNT composite mixtures. We spin-coat these mixtures at various spin-speed rates and spin times over a glass substrate, producing a thin, transparent, solid, conductive layer. Keeping the amount of SWCNTs constant, we vary the weight fraction of our smaller 30-nm latex particles relative to the larger 70-nm-sized ones. We find a maximum in the electrical conductivity up to 370 S/m as a function of the weight fraction of smaller particles, depending on the overall solid content, the spin speed, and the spin time. This maximum occurs at 3-5% of the smaller latex particles. We also find a more than 2-fold increase in conductivity parallel to the radius of spin-coating than perpendicular to it. Atomic force microscopy points at the existence of lanes of latex particles in the spin-coated thin layer, while large-area transmission electron microscopy demonstrates that the SWCNTs are aligned over a grid fixed on the glass substrate during the spin-coating process. We extract the conductivity distribution on the surface of the thin film and translate this into the direction of the SWCNTs in it. PMID:26491888

  5. Bimodal Latex Effect on Spin-Coated Thin Conductive Polymer-Single-Walled Carbon Nanotube Layers.

    PubMed

    Moradi, Mohammad-Amin; Larrakoetxea Angoitia, Katalin; van Berkel, Stefan; Gnanasekaran, Karthikeyan; Friedrich, Heiner; Heuts, Johan P A; van der Schoot, Paul; van Herk, Alex M

    2015-11-10

    We synthesize two differently sized poly(methyl methacrylate-co-tert-butyl acrylate) latexes by emulsion polymerization and mix these with a sonicated single-walled carbon nanotube (SWCNT) dispersion, in order to prepare 3% SWCNT composite mixtures. We spin-coat these mixtures at various spin-speed rates and spin times over a glass substrate, producing a thin, transparent, solid, conductive layer. Keeping the amount of SWCNTs constant, we vary the weight fraction of our smaller 30-nm latex particles relative to the larger 70-nm-sized ones. We find a maximum in the electrical conductivity up to 370 S/m as a function of the weight fraction of smaller particles, depending on the overall solid content, the spin speed, and the spin time. This maximum occurs at 3-5% of the smaller latex particles. We also find a more than 2-fold increase in conductivity parallel to the radius of spin-coating than perpendicular to it. Atomic force microscopy points at the existence of lanes of latex particles in the spin-coated thin layer, while large-area transmission electron microscopy demonstrates that the SWCNTs are aligned over a grid fixed on the glass substrate during the spin-coating process. We extract the conductivity distribution on the surface of the thin film and translate this into the direction of the SWCNTs in it.

  6. Flexible coherent control of plasmonic spin-Hall effect.

    PubMed

    Xiao, Shiyi; Zhong, Fan; Liu, Hui; Zhu, Shining; Li, Jensen

    2015-01-01

    The surface plasmon polariton is an emerging candidate for miniaturizing optoelectronic circuits. Recent demonstrations of polarization-dependent splitting using metasurfaces, including focal-spot shifting and unidirectional propagation, allow us to exploit the spin degree of freedom in plasmonics. However, further progress has been hampered by the inability to generate more complicated and independent surface plasmon profiles for two incident spins, which work coherently together for more flexible and tunable functionalities. Here by matching the geometric phases of the nano-slots on silver to specific superimpositions of the inward and outward surface plasmon profiles for the two spins, arbitrary spin-dependent orbitals can be generated in a slot-free region. Furthermore, motion pictures with a series of picture frames can be assembled and played by varying the linear polarization angle of incident light. This spin-enabled control of orbitals is potentially useful for tip-free near-field scanning microscopy, holographic data storage, tunable plasmonic tweezers, and integrated optical components. PMID:26415636

  7. Flexible coherent control of plasmonic spin-Hall effect

    PubMed Central

    Xiao, Shiyi; Zhong, Fan; Liu, Hui; Zhu, Shining; Li, Jensen

    2015-01-01

    The surface plasmon polariton is an emerging candidate for miniaturizing optoelectronic circuits. Recent demonstrations of polarization-dependent splitting using metasurfaces, including focal-spot shifting and unidirectional propagation, allow us to exploit the spin degree of freedom in plasmonics. However, further progress has been hampered by the inability to generate more complicated and independent surface plasmon profiles for two incident spins, which work coherently together for more flexible and tunable functionalities. Here by matching the geometric phases of the nano-slots on silver to specific superimpositions of the inward and outward surface plasmon profiles for the two spins, arbitrary spin-dependent orbitals can be generated in a slot-free region. Furthermore, motion pictures with a series of picture frames can be assembled and played by varying the linear polarization angle of incident light. This spin-enabled control of orbitals is potentially useful for tip-free near-field scanning microscopy, holographic data storage, tunable plasmonic tweezers, and integrated optical components. PMID:26415636

  8. Verification of Spin Magnetic Attitude Control System using air-bearing-based attitude control simulator

    NASA Astrophysics Data System (ADS)

    Ousaloo, H. S.; Nodeh, M. T.; Mehrabian, R.

    2016-09-01

    This paper accomplishes one goal and it was to verify and to validate a Spin Magnetic Attitude Control System (SMACS) program and to perform Hardware-In-the-Loop (HIL) air-bearing experiments. A study of a closed-loop magnetic spin controller is presented using only magnetic rods as actuators. The magnetic spin rate control approach is able to perform spin rate control and it is verified with an Attitude Control System (ACS) air-bearing MATLAB® SIMULINK® model and a hardware-embedded LABVIEW® algorithm that controls the spin rate of the test platform on a spherical air bearing table. The SIMULINK® model includes dynamic model of air-bearing, its disturbances, actuator emulation and the time delays caused by on-board calculations. The air-bearing simulator is employed to develop, improve, and carry out objective tests of magnetic torque rods and spin rate control algorithm in the experimental framework and to provide a more realistic demonstration of expected performance of attitude control as compared with software-based architectures. Six sets of two torque rods are used as actuators for the SMACS. It is implemented and simulated to fulfill mission requirement including spin the satellite up to 12 degs-1 around the z-axis. These techniques are documented for the full nonlinear equations of motion of the system and the performances of these techniques are compared in several simulations.

  9. Thermal control of the spin pumping damping in ferromagnetic/normal metal interfaces

    NASA Astrophysics Data System (ADS)

    Rezende, S. M.; Rodríguez-Suárez, R. L.; Azevedo, A.

    2014-03-01

    A model is presented for the control of the magnetic relaxation in a ferromagnetic insulator (FMI) in contact with a normal metal (NM) under a thermal gradient applied across the thickness of the bilayer. We show that the thermal gradient modifies the spin pumping damping created by the contact of the NM with the FMI. This results from the bulk magnon spin current generated through the longitudinal spin Seebeck effect that superimposes to the spin pumping current at the FMI/NM interface, changing the FMI magnetic damping. The results of the model explain the experimental data on the control of the magnetic relaxation by thermal gradients measured by the linewidth of the ferromagnetic resonance absorption and by the attenuation of spin-wave packets propagating along a film of single-crystal yttrium iron garnet covered by a very thin platinum layer. Depending on the sign of the gradient, the relaxation rate can be increased or decreased, leading in the latter case to an apparent amplification.

  10. Rare-Earth Triangular Lattice Spin Liquid: A Single-Crystal Study of YbMgGaO4.

    PubMed

    Li, Yuesheng; Chen, Gang; Tong, Wei; Pi, Li; Liu, Juanjuan; Yang, Zhaorong; Wang, Xiaoqun; Zhang, Qingming

    2015-10-16

    YbMgGaO4, a structurally perfect two-dimensional triangular lattice with an odd number of electrons per unit cell and spin-orbit entangled effective spin-1/2 local moments for the Yb(3+) ions, is likely to experimentally realize the quantum spin liquid ground state. We report the first experimental characterization of single-crystal YbMgGaO4 samples. Because of the spin-orbit entanglement, the interaction between the neighboring Yb(3+) moments depends on the bond orientations and is highly anisotropic in the spin space. We carry out thermodynamic and the electron spin resonance measurements to confirm the anisotropic nature of the spin interaction as well as to quantitatively determine the couplings. Our result is a first step towards the theoretical understanding of the possible quantum spin liquid ground state in this system and sheds new light on the search for quantum spin liquids in strong spin-orbit coupled insulators.

  11. Generation and coherent control of pure spin currents via terahertz pulses

    SciTech Connect

    Schüler, Michael Berakdar, Jamal

    2014-04-21

    We inspect the time and spin-dependent, inelastic tunneling in engineered semiconductor-based double quantum well driven by time-structured terahertz pulses. An essential ingredient is an embedded spin-active structure with vibrational modes that scatter the pulse driven carriers. Due to the different time scales of the charge and spin dynamics, the spin-dependent electron-vibron coupling may result in pure net spin current (with negligible charge current). Heating the vibrational site may affect the resulting spin current. Furthermore, by controlling the charge dynamics, the spin dynamics and the generated spin current can be manipulated and switched on and off coherently.

  12. Generalized Momentum Control of the Spin-Stabilized Magnetospheric Multiscale (MMS) Formation

    NASA Technical Reports Server (NTRS)

    Benegalrao, Suyog; Queen, Steven; Shah, Neerav; Blackman, Kathleen

    2015-01-01

    Angular momentum control maneuvers required to keep spin-axis in science box. Traditional approach uses de-coupled modes for pointing, spin, nutation Impractical for MMS Frequency and Number of maneuvers (Orbit Control, Pointing, Nutation, Spin, four observatories, every 2-4 weeks). Difficult to implement de-coupled open-loop control with flexible wire booms. Desire a unified angular momentum controller. Comprehensively control pointing, spin, and nutation.

  13. Enhanced Spin Squeezing in Atomic Ensembles via Control of the Internal Spin States

    NASA Astrophysics Data System (ADS)

    Shojaee, Ezad; Norris, Leigh; Baragiola, Ben; Montano, Enrique; Hemmer, Daniel; Jessen, Poul; Deutsch, Ivan

    2015-05-01

    Abstract: We study the process by which the collective spin squeezing of an ensemble of Cesium atoms is enhanced by control of the internal spin state of the atoms. By increasing the initial atomic projection noise, one can enhance the Faraday interaction that entangles the atoms with a probe. The light acts as a quantum bus for creating atom-atom entanglement via measurement backaction. Further control can be used to transfer this entanglement to metrologically useful squeezing. We numerically simulate this protocol by a stochastic master equation, including QND measurement and optical pumping, which accounts for decoherence and transfer of coherences between magnetic sub-levels. We study the tradeoff between the enhanced entangling interaction and increased rates of decoherence for different initial state preparations. Under realistic conditions, we find that we can achieve squeezing with a ``CAT-State'' superpostion |F = 4, Mz = 4> + |F, Mz = -4> of ~ 9.9 dB and for the spin coherent state |F = 4, Mx = 4> of ~ 7.5 dB. The increased entanglement enabled by the CAT state preparation is partially, but not completely reduced by the increased fragility to decoherence. National Science Foundation.

  14. Single scale cluster expansions with applications to many Boson and unbounded spin systems

    NASA Astrophysics Data System (ADS)

    Lohmann, Martin

    2015-06-01

    We develop a cluster expansion to show exponential decay of correlations for quite general single scale spin systems, as they arise in lattice quantum field theory and discretized functional integral representations for observables of quantum statistical mechanics. We apply our results to the small field approximation to the coherent state correlation functions of the grand canonical Bose gas at negative chemical potential, constructed by Balaban et al. [Ann. Henri Poincaré 11, 151-350 (2010c)], and to N component unbounded spin systems with repulsive two body interaction and massive, possibly complex, covariance. Our cluster expansion is derived by a single application of the Brydges-Kennedy-Abdesselam-Rivasseau interpolation formula.

  15. Single scale cluster expansions with applications to many Boson and unbounded spin systems

    SciTech Connect

    Lohmann, Martin

    2015-06-15

    We develop a cluster expansion to show exponential decay of correlations for quite general single scale spin systems, as they arise in lattice quantum field theory and discretized functional integral representations for observables of quantum statistical mechanics. We apply our results to the small field approximation to the coherent state correlation functions of the grand canonical Bose gas at negative chemical potential, constructed by Balaban et al. [Ann. Henri Poincaré 11, 151–350 (2010c)], and to N component unbounded spin systems with repulsive two body interaction and massive, possibly complex, covariance. Our cluster expansion is derived by a single application of the Brydges-Kennedy-Abdesselam-Rivasseau interpolation formula.

  16. Electrically controllable spin conductance of zigzag silicene nanoribbons in the presence of anti-ferromagnetic exchange field

    NASA Astrophysics Data System (ADS)

    Pournaghavi, Nezhat; Esmaeilzadeh, Mahdi; Ahmadi, Somaieh; Farokhnezhad, Mohsen

    2016-01-01

    We study spin-dependent electron transport properties of zigzag silicene nanoribbons in the presence of anti-ferromagnetic exchange field using a nonequilibrium Green's function method. Applying a transverse electric field, spin splitting can take place and the silicene nanoribbon can work as a spin filter. The spin polarization is calculated and it is shown that the spin filtering is perfect and the spin states of electrons are fully coherent. The spin direction of transmitted electrons through the silicene filter can be easily controlled by changing the transverse electric field direction. Using Hubbard model, we take into account the electron-electron interaction and we find that although this interaction causes some changes in the electron conductance, it has no destructive effect on spin filtering properties. The effect of a single vacancy on electron transport is also investigated and it is found that, the vacancy causes to decrease the electron conductance; however, the spin-dependent properties remain the same. The vacancy in the near of the edges of nanoribbon has less destructive effect on electron conductance than that in the middle.

  17. Understanding spin structure in metallacrown single-molecule magnets using magnetic compton scattering.

    PubMed

    Deb, Aniruddha; Boron, Thaddeus T; Itou, Masayoshi; Sakurai, Yoshiharu; Mallah, Talal; Pecoraro, Vincent L; Penner-Hahn, James E

    2014-04-01

    The 3d-4f mixed metallacrowns frequently show single-molecule magnetic behavior. We have used magnetic Compton scattering to characterize the spin structure and orbital interactions in three isostructural metallacrowns: Gd2Mn4, Dy2Mn4, and Y2Mn4. These data allow the direct determination of the spin only contribution to the overall magnetic moment. We find that the lanthanide 4f spin in Gd2Mn4 and Dy2Mn4 is aligned parallel to the Mn 3d spin. For Y2Mn4 (manganese-only spin) we find evidence for spin delocalization into the O 2p orbitals. Comparing the magnetic Compton scattering data with SQUID studies that measure the total magnetic moment suggests that Gd2Mn4 and Y2Mn4 have only a small orbital contribution to the moment. In contrast, the total magnetic moment for Dy2Mn4 MCs is much larger than the spin-only moment, demonstrating a significant orbital contribution to the overall magnetic moment. Overall, these data provide direct insight into the correlation of molecular design with molecular magnetic properties.

  18. Spin wave dynamics in Heisenberg ferromagnetic/antiferromagnetic single-walled nanotubes

    NASA Astrophysics Data System (ADS)

    Mi, Bin-Zhou

    2016-09-01

    The spin wave dynamics, including the magnetization, spin wave dispersion relation, and energy level splitting, of Heisenberg ferromagnetic/antiferromagnetic single-walled nanotubes are systematically calculated by use of the double-time Green's function method within the random phase approximation. The role of temperature, diameter of the tube, and wave vector on spin wave energy spectrum and energy level splitting are carefully analyzed. There are two categories of spin wave modes, which are quantized and degenerate, and the total number of independent magnon branches is dependent on diameter of the tube, caused by the physical symmetry of nanotubes. Moreover, the number of flat spin wave modes increases with diameter of the tube rising. The spin wave energy and the energy level splitting decrease with temperature rising, and become zero as temperature reaches the critical point. At any temperature, the energy level splitting varies with wave vector, and for a larger wave vector it is smaller. When pb=π, the boundary of first Brillouin zone, spin wave energies are degenerate, and the energy level splittings are zero.

  19. Anisotropy: Spin order and magnetization of single-crystalline Cu4(OH) 6FBr barlowite

    NASA Astrophysics Data System (ADS)

    Han, Tian-Heng; Isaacs, Eric D.; Schlueter, John A.; Singleton, John

    2016-06-01

    Despite decades-long fascination, the difficulty of maintaining high lattice symmetry in frustrated nonbipartite S =1/2 materials that can also be made into high-quality single crystals has been a persistent challenge. Here we report magnetization studies of a single-crystal sample of barlowite, Cu4(OH) 6 FBr , which has a geometrically perfect kagome motif. At T ≤4.2 K and 35 ≤μ0H ≤65 T, the interlayer spins are fully polarized, and the kagome-intrinsic magnetization is consistent with a Heisenberg model having J /kB=-180 K. Several field-driven anomalies are observed, having varied scalings with temperature. At an applied field, kagome disorder caused by the interlayer spins is smaller than that in herbertsmithite. At T ≤ 15 K, the bulk magnetic moment comes from the interlayer spins. An almost coplanar spin order suggests that the magnitude of in-plane Dzyaloshinskii-Moriya interaction is smaller than 0.006(6) J . On the other hand, the possibility of a spin-liquid state in the kagome lattice coexisting with ordered interlayer spins is left open.

  20. Linear spin wave theory for single-Q incommensurate magnetic structures.

    PubMed

    Toth, S; Lake, B

    2015-04-29

    Linear spin wave theory provides the leading term in the calculation of the excitation spectra of long-range ordered magnetic systems as a function of 1/√S. This term is acquired using the Holstein-Primakoff approximation of the spin operator and valid for small δS fluctuations of the ordered moment. We propose an algorithm that allows magnetic ground states with general moment directions and single-Q incommensurate ordering wave vector using a local coordinate transformation for every spin and a rotating coordinate transformation for the incommensurability. Finally we show, how our model can determine the spin wave spectrum of the magnetic C-site langasites with incommensurate order. PMID:25817594

  1. Spin polarized surface resonance bands in single layer Bi on Ge(1 1 1)

    NASA Astrophysics Data System (ADS)

    Bottegoni, F.; Calloni, A.; Bussetti, G.; Camera, A.; Zucchetti, C.; Finazzi, M.; Duò, L.; Ciccacci, F.

    2016-05-01

    The spin features of surface resonance bands in single layer Bi on Ge(1 1 1) are studied by means of spin- and angle-resolved photoemission spectroscopy and inverse photoemission spectroscopy. We characterize the occupied and empty surface states of Ge(1 1 1) and show that the deposition of one monolayer of Bi on Ge(1 1 1) leads to the appearance of spin-polarized surface resonance bands. In particular, the C 3v symmetry, which Bi adatoms adopt on Ge(1 1 1), allows for the presence of Rashba-like occupied and unoccupied electronic states around the \\overline{\\text{M}} point of the Bi surface Brillouin zone with a giant spin-orbit constant |{α\\text{R}}| =≤ft(1.4+/- 0.1\\right) eV · Å.

  2. Protein carbon-13 spin systems by a single two-dimensional nuclear magnetic resonance experiment

    SciTech Connect

    Oh, B.H.; Westler, W.M.; Darba, P.; Markley, J.L.

    1988-05-13

    By applying a two-dimensional double-quantum carbon-13 nuclear magnetic resonance experiment to a protein uniformly enriched to 26% carbon-13, networks of directly bonded carbon atoms were identified by virtue of their one-bond spin-spin couplings and were classified by amino acid type according to their particular single- and double-quantum chemical shift patterns. Spin systems of 75 of the 98 amino acid residues in a protein, oxidized Anabaena 7120 ferredoxin (molecular weight 11,000), were identified by this approach, which represents a key step in an improved methodology for assigning protein nuclear magnetic resonance spectra. Missing spin systems corresponded primarily to residues located adjacent to the paramagnetic iron-sulfur cluster. 25 references, 2 figures.

  3. Electrostatic Spin Crossover in a Molecular Junction of a Single-Molecule Magnet Fe2

    NASA Astrophysics Data System (ADS)

    Hao, Hua; Zheng, Xiaohong; Song, Lingling; Wang, Ruining; Zeng, Zhi

    2012-01-01

    Spin crossover by means of an electric bias is investigated by spin-polarized density-functional theory calculations combined with the Keldysh nonequilibrium Green’s technique in a molecular junction, where an individual single-molecule magnet Fe2(acpybutO)(O2CMe)(NCS)2 is sandwiched between two infinite Au(100) nanoelectrodes. Our study demonstrates that the spin crossover, based on the Stark effect, is achieved in this molecular junction under an electric bias but not in the isolated molecule under external electric fields. The main reason is that the polarizability of the molecular junction has an opposite sign to that of the isolated molecule, and thus from the Stark effect the condition for the spin crossover in the molecular junction is contrary to that in the isolated molecule.

  4. Generalized Momentum Control of the Spin-Stabilized Magnetospheric Multiscale Formation

    NASA Technical Reports Server (NTRS)

    Queen, Steven Z.; Shah, Neerav; Benegalrao, Suyog S.; Blackman, Kathie

    2015-01-01

    The Magnetospheric Multiscale (MMS) mission consists of four identically instrumented, spin-stabilized observatories elliptically orbiting the Earth in a tetrahedron formation. The on-board attitude control system adjusts the angular momentum of the system using a generalized thruster-actuated control system that simultaneously manages precession, nutation and spin. Originally developed using Lyapunov control-theory with rate-feedback, a published algorithm has been augmented to provide a balanced attitude/rate response using a single weighting parameter. This approach overcomes an orientation sign-ambiguity in the existing formulation, and also allows for a smoothly tuned-response applicable to both a compact/agile spacecraft, as well as one with large articulating appendages.

  5. Circuit-quantum electrodynamics with direct magnetic coupling to single-atom spin qubits in isotopically enriched {sup 28}Si

    SciTech Connect

    Tosi, Guilherme Mohiyaddin, Fahd A.; Morello, Andrea; Huebl, Hans

    2014-08-15

    Recent advances in silicon nanofabrication have allowed the manipulation of spin qubits that are extremely isolated from noise sources, being therefore the semiconductor equivalent of single atoms in vacuum. We investigate the possibility of directly coupling an electron spin qubit to a superconducting resonator magnetic vacuum field. By using resonators modified to increase the vacuum magnetic field at the qubit location, and isotopically purified {sup 28}Si substrates, it is possible to achieve coupling rates faster than the single spin dephasing. This opens up new avenues for circuit-quantum electrodynamics with spins, and provides a pathway for dispersive read-out of spin qubits via superconducting resonators.

  6. Optimal control of two coupled spinning particles in the Euler-Lagrange picture

    NASA Astrophysics Data System (ADS)

    Delgado-Téllez, M.; Ibort, A.; Rodríguez de la Peña, T.; Salmoni, R.

    2016-01-01

    A family of optimal control problems for a single and two coupled spinning particles in the Euler-Lagrange formalism is discussed. A characteristic of such problems is that the equations controlling the system are implicit and a reduction procedure to deal with them must be carried out. The reduction of the implicit control equations arising in these problems will be discussed in the slightly more general setting of implicit equations defined by invariant one-forms on Lie groups. As an example the first order differential equations describing the extremal solutions of an optimal control problem for a single spinning particle, obtained by using Pontryagin’s Maximum Principle (PMP), will be found and shown to be completely integrable. Then, again using PMP, solutions for the problem of two coupled spinning particles will be characterized as solutions of a system of coupled non-linear matrix differential equations. The reduction of the implicit system will show that the reduced space for them is the product of the space of states for the independent systems, implying the absence of ‘entanglement’ in this instance. Finally, it will be shown that, in the case of identical systems, the degree three matrix polynomial differential equations determined by the optimal feedback law, constitute a completely integrable Hamiltonian system and some of its solutions are described explicitly.

  7. Spin-Controlled Photoluminescence in Hybrid Nanoparticles Purple Membrane System

    PubMed Central

    2016-01-01

    Spin-dependent photoluminescence (PL) quenching of CdSe nanoparticles (NPs) has been explored in the hybrid system of CdSe NP purple membrane, wild-type bacteriorhodopsin (bR) thin film on a ferromagnetic (Ni-alloy) substrate. A significant change in the PL intensity from the CdSe NPs has been observed when spin-specific charge transfer occurs between the retinal and the magnetic substrate. This feature completely disappears in a bR apo membrane (wild-type bacteriorhodopsin in which the retinal protein covalent bond was cleaved), a bacteriorhodopsin mutant (D96N), and a bacteriorhodopsin bearing a locked retinal chromophore (isomerization of the crucial C13=C14 retinal double bond was prevented by inserting a ring spanning this bond). The extent of spin-dependent PL quenching of the CdSe NPs depends on the absorption of the retinal, embedded in wild-type bacteriorhodopsin. Our result suggests that spin-dependent charge transfer between the retinal and the substrate controls the PL intensity from the NPs. PMID:27018195

  8. Controllable spin-charge transport in strained graphene nanoribbon devices

    NASA Astrophysics Data System (ADS)

    Diniz, Ginetom S.; Guassi, Marcos R.; Qu, Fanyao

    2014-09-01

    We theoretically investigate the spin-charge transport in two-terminal device of graphene nanoribbons in the presence of a uniform uniaxial strain, spin-orbit coupling, exchange field, and smooth staggered potential. We show that the direction of applied strain can efficiently tune strain-strength induced oscillation of band-gap of armchair graphene nanoribbon (AGNR). It is also found that electronic conductance in both AGNR and zigzag graphene nanoribbon (ZGNR) oscillates with Rashba spin-orbit coupling akin to the Datta-Das field effect transistor. Two distinct strain response regimes of electronic conductance as function of spin-orbit couplings magnitude are found. In the regime of small strain, conductance of ZGNR presents stronger strain dependence along the longitudinal direction of strain. Whereas for high values of strain shows larger effect for the transversal direction. Furthermore, the local density of states shows that depending on the smoothness of the staggered potential, the edge states of AGNR can either emerge or be suppressed. These emerging states can be determined experimentally by either spatially scanning tunneling microscope or by scanning tunneling spectroscopy. Our findings open up new paradigms of manipulation and control of strained graphene based nanostructure for application on novel topological quantum devices.

  9. Controllable spin-charge transport in strained graphene nanoribbon devices

    SciTech Connect

    Diniz, Ginetom S. Guassi, Marcos R.; Qu, Fanyao

    2014-09-21

    We theoretically investigate the spin-charge transport in two-terminal device of graphene nanoribbons in the presence of a uniform uniaxial strain, spin-orbit coupling, exchange field, and smooth staggered potential. We show that the direction of applied strain can efficiently tune strain-strength induced oscillation of band-gap of armchair graphene nanoribbon (AGNR). It is also found that electronic conductance in both AGNR and zigzag graphene nanoribbon (ZGNR) oscillates with Rashba spin-orbit coupling akin to the Datta-Das field effect transistor. Two distinct strain response regimes of electronic conductance as function of spin-orbit couplings magnitude are found. In the regime of small strain, conductance of ZGNR presents stronger strain dependence along the longitudinal direction of strain. Whereas for high values of strain shows larger effect for the transversal direction. Furthermore, the local density of states shows that depending on the smoothness of the staggered potential, the edge states of AGNR can either emerge or be suppressed. These emerging states can be determined experimentally by either spatially scanning tunneling microscope or by scanning tunneling spectroscopy. Our findings open up new paradigms of manipulation and control of strained graphene based nanostructure for application on novel topological quantum devices.

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

    PubMed

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

    2012-11-15

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

  11. Ferromagnetic spin-glass behaviour in single-crystalline U2 IrSi3.

    PubMed

    Szlawska, M; Majewicz, M; Kaczorowski, D

    2014-03-26

    A single crystal of the U-based ternary silicide U(2)IrSi(3) was investigated by means of magnetic, resistivity and heat-capacity measurements performed in wide ranges of temperature and external magnetic fields. The results hint at the formation of a non-trivial magnetic ground state in which ferromagnetic ordering coexists with spin-glass freezing. PMID:24594881

  12. 1020MHz single-channel proton fast magic angle spinning solid-state NMR spectroscopy.

    PubMed

    Pandey, Manoj Kumar; Zhang, Rongchun; Hashi, Kenjiro; Ohki, Shinobu; Nishijima, Gen; Matsumoto, Shinji; Noguchi, Takashi; Deguchi, Kenzo; Goto, Atsushi; Shimizu, Tadashi; Maeda, Hideaki; Takahashi, Masato; Yanagisawa, Yoshinori; Yamazaki, Toshio; Iguchi, Seiya; Tanaka, Ryoji; Nemoto, Takahiro; Miyamoto, Tetsuo; Suematsu, Hiroto; Saito, Kazuyoshi; Miki, Takashi; Ramamoorthy, Ayyalusamy; Nishiyama, Yusuke

    2015-12-01

    This study reports a first successful demonstration of a single channel proton 3D and 2D high-throughput ultrafast magic angle spinning (MAS) solid-state NMR techniques in an ultra-high magnetic field (1020MHz) NMR spectrometer comprised of HTS/LTS magnet. High spectral resolution is well demonstrated.

  13. Spin-1 atoms in optical superlattices: Single-atom tunneling and entanglement

    SciTech Connect

    Wagner, Andreas; Bruder, Christoph; Demler, Eugene

    2011-12-15

    We examine spinor Bose-Einstein condensates in optical superlattices theoretically using a Bose-Hubbard Hamiltonian that takes spin effects into account. Assuming that a small number of spin-1 bosons is loaded in an optical potential, we study single-particle tunneling that occurs when one lattice site is ramped up relative to a neighboring site. Spin-dependent effects modify the tunneling events in a qualitative and quantitative way. Depending on the asymmetry of the double well, different types of magnetic order occur, making the system of spin-1 bosons in an optical superlattice a model for mesoscopic magnetism. We use a double-well potential as a unit cell for a one-dimensional superlattice. Homogeneous and inhomogeneous magnetic fields are applied, and the effects of the linear and the quadratic Zeeman shifts are examined. We also investigate the bipartite entanglement between the sites and construct states of maximal entanglement. The entanglement in our system is due to both orbital and spin degrees of freedom. We calculate the contribution of orbital and spin entanglements and show that the sum of these two terms gives a lower bound for the total entanglement.

  14. Spin tests of a single-engine, high-wing light airplane

    NASA Technical Reports Server (NTRS)

    Stewart, E. C.; Suit, W. T.; Moul, T. M.; Brown, P. W.

    1982-01-01

    The airplane has a relatively steep spin mode (low angle of attack) with a high load factor and high velocity. The airplane recovers almost immediately after any deviation from the prospin control positions, except for one maneuver with reduced flexibility in the elevator control system.

  15. On the control of spin-boson systems

    SciTech Connect

    Boscain, Ugo; Mason, Paolo; Panati, Gianluca; Sigalotti, Mario

    2015-09-15

    In this paper, we study the so-called spin-boson system, namely, a two-level system in interaction with a distinguished mode of a quantized bosonic field. We give a brief description of the controlled Rabi and Jaynes–Cummings models and we discuss their appearance in the mathematics and physics literature. We then study the controllability of the Rabi model when the control is an external field acting on the bosonic part. Applying geometric control techniques to the Galerkin approximation and using perturbation theory to guarantee non-resonance of the spectrum of the drift operator, we prove approximate controllability of the system, for almost every value of the interaction parameter.

  16. Interactions between SAS-C spacecraft nutations and spin control system

    NASA Technical Reports Server (NTRS)

    Tossman, B. E.; Thayer, D. L.

    1974-01-01

    The SAS-C spacecraft is stabilized by a momentum biased reaction wheel and passive nutation damper. A closed-loop low-speed spacecraft spin rate control system is included which uses a single-axis gyro and a variable speed range on the reaction wheel. Dynamic instability can result from interactions among the gyro, damper, and spacecraft dynamic unbalance. This instability may be aggravated by gyro angular misalignment, gyro error signals, and spacecraft nutations. Analytic eigenvector, and digital computer analyses of the coupled systems are presented. Mechanisms for instability are described as well as the effects that gyro error signal, tilt, and spacecraft dynamic unbalance produce on control system performance.

  17. Electron-hole asymmetry of spin injection and transport in single-layer graphene.

    PubMed

    Han, Wei; Wang, W H; Pi, K; McCreary, K M; Bao, W; Li, Yan; Miao, F; Lau, C N; Kawakami, R K

    2009-04-01

    Spin-dependent properties of single-layer graphene (SLG) have been studied by nonlocal spin valve measurements at room temperature. Gate voltage dependence shows that the nonlocal magnetoresistance (MR) is proportional to the conductivity of the SLG, which is the predicted behavior for transparent ferromagnetic-nonmagnetic contacts. While the electron and hole bands in SLG are symmetric, gate voltage and bias dependence of the nonlocal MR reveal an electron-hole asymmetry in which the nonlocal MR is roughly independent of bias for electrons, but varies significantly with bias for holes. PMID:19392401

  18. Transverse single spin asymmetry in Drell-Yan production in polarized pA collisions

    NASA Astrophysics Data System (ADS)

    Zhou, Jian

    2015-07-01

    We study the transverse single spin asymmetry in Drell-Yan production in pA collisions with incoming protons being transversely polarized. We carry out the calculation using a newly developed hybrid approach. The polarized cross section computed in the hybrid approach is consistent with that obtained from the usual TMD factorization at low transverse momentum as expected, whereas at high transverse momentum, color entanglement effect is found to play a role in contributing to the spin asymmetry of Drell-Yan production, though it is a 1 /Nc2 suppressed effect.

  19. Transverse single spin asymmetry in direct photon production in polarized pA collisions

    NASA Astrophysics Data System (ADS)

    Schäfer, Andreas; Zhou, Jian

    2014-08-01

    We study the transverse single spin asymmetry in direct photon production in pA collisions with incoming protons being transversely polarized. To facilitate the calculation, we formulate a hybrid approach in which the nucleus is treated in the color glass condensate framework, while the collinear twist-3 formalism is applied on the proton side. It has been found that an additional term that arises from color entanglement shows up in the spin-dependent differential cross section. The fact that this additional term is perturbatively calculable allows us to quantitatively study color entanglement effects.

  20. Final-state interaction as origin of single-spin asymmetry in semi-inclusive DIS

    SciTech Connect

    Hwang, D.S.

    2005-05-06

    Recent measurements from the HERMES, SMC, CLAS and COMPASS collaborations show a remarkably large azimuthal single-spin asymmetries of the proton in semi-inclusive pion leptoproduction {gamma}*(q)p{up_arrow} {yields} {pi}X. The existence of such single-spin asymmetries requires a phase difference between two amplitudes coupling the proton target with J{sub p}{sup z} = {+-}(1/2) to the same final-state, the same amplitudes which are necessary to produce a nonzero proton anomalous magnetic moment. We show that the exchange of gauge particles between the outgoing quark and the proton spectators produces a Coulomb-like complex phase which depends on the angular momentum Lz of the proton's constituents and is thus distinct for different proton spin amplitudes. We then find that final-state interactions from gluon exchange between the outgoing quark and the target spectator system lead to single-spin asymmetries at leading twist in perturbative QCD; i.e., the rescattering corrections are not power-law suppressed at large photon virtuality Q2 at fixed xbj.

  1. Chip-Scale Nanofabrication of Single Spins and Spin Arrays in Diamond

    SciTech Connect

    Toyli, David M.; Weis, Christoph D.; Fuchs, D.; Schenkel, Thomas; Awschalom, David D.

    2010-07-02

    We demonstrate a technique to nanofabricate nitrogen vacancy (NV) centers in diamond based on broad-beam nitrogen implantation through apertures in electron beam lithography resist. This method enables high-throughput nanofabrication of single NV centers on sub-100-nm length scales. Secondary ion mass spectroscopy measurements facilitate depth profiling of the implanted nitrogen to provide three-dimensional characterization of the NV center spatial distribution. Measurements of NV center coherence with on-chip coplanar waveguides suggest a pathway for incorporating this scalable nanofabrication technique in future quantum applications.

  2. Large-spin and large-winding expansions of giant magnons and single spikes

    NASA Astrophysics Data System (ADS)

    Floratos, Emmanuel; Linardopoulos, Georgios

    2015-08-01

    We generalize the method of our recent paper on the large-spin expansions of Gubser-Klebanov-Polyakov (GKP) strings to the large-spin and large-winding expansions of finite-size giant magnons and finite-size single spikes. By expressing the energies of long open strings in R ×S2 in terms of Lambert's W-function, we compute the leading, subleading and next-to-subleading series of classical exponential corrections to the dispersion relations of Hofman-Maldacena giant magnons and infinite-winding single spikes. We also compute the corresponding expansions in the doubled regions of giant magnons and single spikes that are respectively obtained when their angular and linear velocities become smaller or greater than unity.

  3. Note: Time-gated 3D single quantum dot tracking with simultaneous spinning disk imaging

    SciTech Connect

    DeVore, M. S.; Stich, D. G.; Keller, A. M.; Phipps, M. E.; Hollingsworth, J. A.; Goodwin, P. M.; Werner, J. H.; Cleyrat, C.; Lidke, D. S.; Wilson, B. S.

    2015-12-15

    We describe recent upgrades to a 3D tracking microscope to include simultaneous Nipkow spinning disk imaging and time-gated single-particle tracking (SPT). Simultaneous 3D molecular tracking and spinning disk imaging enable the visualization of cellular structures and proteins around a given fluorescently labeled target molecule. The addition of photon time-gating to the SPT hardware improves signal to noise by discriminating against Raman scattering and short-lived fluorescence. In contrast to camera-based SPT, single-photon arrival times are recorded, enabling time-resolved spectroscopy (e.g., measurement of fluorescence lifetimes and photon correlations) to be performed during single molecule/particle tracking experiments.

  4. Note: Time-gated 3D single quantum dot tracking with simultaneous spinning disk imaging.

    PubMed

    DeVore, M S; Stich, D G; Keller, A M; Cleyrat, C; Phipps, M E; Hollingsworth, J A; Lidke, D S; Wilson, B S; Goodwin, P M; Werner, J H

    2015-12-01

    We describe recent upgrades to a 3D tracking microscope to include simultaneous Nipkow spinning disk imaging and time-gated single-particle tracking (SPT). Simultaneous 3D molecular tracking and spinning disk imaging enable the visualization of cellular structures and proteins around a given fluorescently labeled target molecule. The addition of photon time-gating to the SPT hardware improves signal to noise by discriminating against Raman scattering and short-lived fluorescence. In contrast to camera-based SPT, single-photon arrival times are recorded, enabling time-resolved spectroscopy (e.g., measurement of fluorescence lifetimes and photon correlations) to be performed during single molecule/particle tracking experiments.

  5. Theory of electrically controlled resonant tunneling spin devices

    NASA Technical Reports Server (NTRS)

    Ting, David Z. -Y.; Cartoixa, Xavier

    2004-01-01

    We report device concepts that exploit spin-orbit coupling for creating spin polarized current sources using nonmagnetic semiconductor resonant tunneling heterostructures, without external magnetic fields. The resonant interband tunneling psin filter exploits large valence band spin-orbit interaction to provide strong spin selectivity.

  6. High-fidelity transfer and storage of photon states in a single nuclear spin

    NASA Astrophysics Data System (ADS)

    Yang, Sen; Wang, Ya; Rao, D. D. Bhaktavatsala; Hien Tran, Thai; Momenzadeh, Ali S.; Markham, M.; Twitchen, D. J.; Wang, Ping; Yang, Wen; Stöhr, Rainer; Neumann, Philipp; Kosaka, Hideo; Wrachtrup, Jörg

    2016-08-01

    Long-distance quantum communication requires photons and quantum nodes that comprise qubits for interaction with light and good memory capabilities, as well as processing qubits for the storage and manipulation of photons. Owing to the unavoidable photon losses, robust quantum communication over lossy transmission channels requires quantum repeater networks. A necessary and highly demanding prerequisite for these networks is the existence of quantum memories with long coherence times to reliably store the incident photon states. Here we demonstrate the high-fidelity (˜98%) coherent transfer of a photon polarization state to a single solid-state nuclear spin that has a coherence time of over 10 s. The storage process is achieved by coherently transferring the polarization state of a photon to an entangled electron-nuclear spin state of a nitrogen-vacancy centre in diamond. The nuclear spin-based optical quantum memory demonstrated here paves the way towards an absorption-based quantum repeater network.

  7. Normal and inverse bulk spin valve effects in single-crystal ruthenates

    NASA Astrophysics Data System (ADS)

    Peng, Jin; Hu, J.; Gu, X. M.; Zhou, G. T.; Liu, J. Y.; Zhang, F. M.; Wu, X. S.; Mao, Z. Q.

    2016-04-01

    The current-perpendicular-to-plane magnetoresistivity (CPP-MR) /ρc(B ) is investigated in single crystal ruthenates Ca3(Ru1-xTix)2O7 (x = 0.02). This material is naturally composed of ferromagnetic metallic bilayers (Ru,Ti)O2 separated by nonmagnetic insulating layers of Ca2O2, resulting in tunneling magnetoresistivity. Non-monotonic ρc(B ) curves as well as the inverse spin valve effect are observed around the magnetic phase transition associating with the metal-to-insulator transition. A spin dependent tunneling model with alternate distribution of hard and soft magnetic layers [(Ru,Ti)O2] is proposed to explain the exotic CPP-MR behavior. This eccentric CPP-MR behavior highlights the strong spin-charge coupling in double-layered ruthenates and provides a potential material for spintronic devices.

  8. High-fidelity transfer and storage of photon states in a single nuclear spin

    NASA Astrophysics Data System (ADS)

    Yang, Sen; Wang, Ya; Rao, D. D. Bhaktavatsala; Hien Tran, Thai; Momenzadeh, Ali S.; Markham, M.; Twitchen, D. J.; Wang, Ping; Yang, Wen; Stöhr, Rainer; Neumann, Philipp; Kosaka, Hideo; Wrachtrup, Jörg

    2016-08-01

    Long-distance quantum communication requires photons and quantum nodes that comprise qubits for interaction with light and good memory capabilities, as well as processing qubits for the storage and manipulation of photons. Owing to the unavoidable photon losses, robust quantum communication over lossy transmission channels requires quantum repeater networks. A necessary and highly demanding prerequisite for these networks is the existence of quantum memories with long coherence times to reliably store the incident photon states. Here we demonstrate the high-fidelity (∼98%) coherent transfer of a photon polarization state to a single solid-state nuclear spin that has a coherence time of over 10 s. The storage process is achieved by coherently transferring the polarization state of a photon to an entangled electron–nuclear spin state of a nitrogen–vacancy centre in diamond. The nuclear spin-based optical quantum memory demonstrated here paves the way towards an absorption-based quantum repeater network.

  9. Antiferromagnetic spin excitations in single crystals of nonsuperconducting Li$_{1-x}$FeAs

    SciTech Connect

    Wang, Meng; Wang, X.C.; Harriger, Leland W; Luo, H.Q.; Zhao, Yang; Lynn, J. W.; Liu, Q.Q.; Jin, C.Q.; Fang, Chen; Hu, Jiangping; Dai, Pengcheng

    2011-01-01

    We use neutron scattering to determine spin excitations in single crystals of nonsuperconducting Li1 xFeAs throughout the Brillouin zone. Although angle resolved photoemission experiments and local density approximation calculations suggest poor Fermi surface nesting conditions for antiferromagnetic (AF) order, spin excitations in Li1 xFeAs occur at the AF wave vectors Q = (1,0) at low energies, but move to wave vectors Q = ( 0.5, 0.5) near the zone boundary with a total magnetic bandwidth comparable to that of BaFe2As2. These results reveal that AF spin excitations still dominate the low-energy physics of these materials and suggest both itinerancy and strong electron-electron correlations are essential to understand the measured magnetic excitations.

  10. Negative magnetoresistance in a vertical single-layer graphene spin valve at room temperature.

    PubMed

    Singh, Arun Kumar; Eom, Jonghwa

    2014-02-26

    Single-layer graphene (SLG) is an ideal material for spintronics because of its high charge-carrier mobility, long spin lifetime resulting from the small spin-orbit coupling, and hyperfine interactions of carbon atoms. Here, we report a vertical spin valve with SLG with device configuration Co/SLG/Al2O3/Ni. We observed negative magnetoresistance (-0.4%) for the Co/SLG/Al2O3/Ni junction at room temperature. However, the Co/Al2O3/Ni junction, which is without graphene, shows positive magnetoresistance. The current-voltage (I-V) characteristics of both Co/SLG/Al2O3/Ni and Co/Al2O3/Ni junctions are nonlinear, and this reveals that charge transport occurs by a tunneling mechanism. We have also explained the reason for negative magnetoresistance for the Co/SLG/Al2O3/Ni junction. PMID:24495123

  11. Optically controlled electron-nuclear spin dynamics in a quantum dot

    NASA Astrophysics Data System (ADS)

    Barnes, Edwin; Economou, Sophia

    2011-03-01

    In recent years, a large number of experiments involving coherent and incoherent control of electron spins in quantum dots have revealed the important role of the nuclear spins of the host material. Experiments with optical controls, both pulsed and continuous wave, have shown that the feedback of the nuclear spins on the electron spin strongly affects the electron spin response. However, a microscopic theory of this mechanism is not available at present. We introduce a formalism that allows us to investigate this system without invoking any phenomenological spin-flip rates for the nuclei. We derive the electron-nuclear dynamics under the influence of external periodic pulsed control to second order in the electron-nuclear hyperfine coupling. Our formalism should have wide applications in both coherently and incoherently driven electron spins interacting with a nuclear spin bath, including self-assembled and gated quantum dots. Work (EB) supported by LPS-CMTC and CNAM.

  12. Teleportation of electronic many-qubit states encoded in the electron spin of quantum dots via single photons.

    PubMed

    Leuenberger, Michael N; Flatté, Michael E; Awschalom, D D

    2005-03-18

    We propose a teleportation scheme that relies only on single-photon measurements and Faraday rotation, for teleportation of many-qubit entangled states stored in the electron spins of a quantum dot system. The interaction between a photon and the two electron spins, via Faraday rotation in microcavities, establishes Greenberger-Horne-Zeilinger entanglement in the spin-photon-spin system. The appropriate single-qubit measurements, and the communication of two classical bits, produce teleportation. This scheme provides the essential link between spintronic and photonic quantum information devices by permitting quantum information to be exchanged between them.

  13. Measurement of Single and Double Spin Asymmetries in Deep Inelastic Pion Electroproduction with a Longitudinally Polarized Target

    SciTech Connect

    Avakian, H; Bosted, P; Elouadrhiri, L; Adhikari, K P; Aghasyan, M; Amaryan, M; Anghinolfi, M; Baghdasaryan, H; Ball, J; Battaglieri, M; Bedlinskiy, I; Biselli, A S; Branford, D; Briscoe, W J; Brooks, W; Carman, D S; Casey, L; Cole, P L; Collins, P; Crabb, D; Crede, V; D'Angelo, A; Daniel, A; Dashyan, N; DeVita, R; DeSanctis, E; Deur, A; Dey, B; Dhamija, S; Dickson, R; Djalali, C; Dodge, G; Doughty, D; Dupre, R; El Alaoui, A; Eugenio, P; Fegan, S; Fersch, M; Guler, N; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Hassall, N; Heddle, D; Hicks, K; Holtrop, M; Ilieva, Y; Ireland, D G; Isupov, E L; Jawalkar, S S; Jo, H S; Joo, K; Keller, D; Khandaker, M; Khetarpal,; Kim, W; Klein, A; Klein, F J; Konczykowski, P; Kubarovsky, V; Kuhn, S E; Kuleshov, S V; Kuznetsov, V; Livingston, K; Lu, H Y; Markov, N; Mayer, M; McAndrew, J; McCracken, M E; McKInnon, B; Meyer, C A; Mineeva, T; Mirazita, M; Mokeev, V; Moreno, B; Moriya, K; Morrison, B; Moutarde, H; Munevar, E; Nadel-Turonski, P; Nasseripour, R; Niccolai, S; Niculescu, G; Niculescu, I; Niroula, M R; Osipenko, M; Ostrovidov, A I; Paremuzyan, R; Park, K; Park, S; Pasyuk, E; Anefalos Pereira, S; Perrin, Y; Pisano, S; Pogorelko, O; Price, J W; Procureur, S; Prok, Protopopescu; Raue, B A; Ricco, G; Ripani, M; Rosner, G; Rossi, P; Sabatie, F; Saini, M S; Salamanca, J; Salgado, C; Schumacher, R A; Seder, E; Seraydaryan, H; Sharabian, Y G; Sober, D I; Sokhan, D; Stapanyan, S S; Stepanyan, S; Stoler, P; Strauch, S; Suleiman, R; Taiuti, M; Tedeschi, D J; Tkachenko, S; Ungaro, M; Vernarsky, B; Vineyard, M F; Voutier, E; Watts, D P; Weinstein, L B; Weygand, D P; Wood, M H; Zhang, J; Zhao, B; Zhao, Z W

    2010-12-01

    We report the first measurement of the transverse momentum dependence of double spin asymmetries in semi-inclusive production of pions in deep inelastic scattering off the longitudinally polarized proton. Data have been obtained using a polarized electron beam of 5.7 GeV with the CLAS detector at the Thomas Jefferson National Accelerator Facility (JLab). A significant non-zero $\\sin2\\phi$ single spin asymmetry was also observed for the first time indicating strong spin-orbit correlations for transversely polarized quarks in the longitudinally polarized proton. The azimuthal modulations of single spin asymmetries have been measured over a wide kinematic range.

  14. Charge and spin transport in single and packed ruthenium-terpyridine molecular devices: Insight from first-principles calculations

    NASA Astrophysics Data System (ADS)

    Morari, C.; Buimaga-Iarinca, L.; Rungger, I.; Sanvito, S.; Melinte, S.; Rignanese, G.-M.

    2016-08-01

    Using first-principles calculations, we study the electronic and transport properties of rutheniumterpyridine molecules sandwiched between two Au(111) electrodes. We analyse both single and packed molecular devices, more amenable to scaling and realistic integration approaches. The devices display all together robust negative differential resistance features at low bias voltages. Remarkably, the electrical control of the spin transport in the studied systems implies a subtle distribution of the magnetisation density within the biased devices and highlights the key role of the Au(111) electrical contacts.

  15. Charge and spin transport in single and packed ruthenium-terpyridine molecular devices: Insight from first-principles calculations.

    PubMed

    Morari, C; Buimaga-Iarinca, L; Rungger, I; Sanvito, S; Melinte, S; Rignanese, G-M

    2016-01-01

    Using first-principles calculations, we study the electronic and transport properties of rutheniumterpyridine molecules sandwiched between two Au(111) electrodes. We analyse both single and packed molecular devices, more amenable to scaling and realistic integration approaches. The devices display all together robust negative differential resistance features at low bias voltages. Remarkably, the electrical control of the spin transport in the studied systems implies a subtle distribution of the magnetisation density within the biased devices and highlights the key role of the Au(111) electrical contacts. PMID:27550064

  16. Charge and spin transport in single and packed ruthenium-terpyridine molecular devices: Insight from first-principles calculations

    PubMed Central

    Morari, C.; Buimaga-Iarinca, L.; Rungger, I.; Sanvito, S.; Melinte, S.; Rignanese, G.-M.

    2016-01-01

    Using first-principles calculations, we study the electronic and transport properties of rutheniumterpyridine molecules sandwiched between two Au(111) electrodes. We analyse both single and packed molecular devices, more amenable to scaling and realistic integration approaches. The devices display all together robust negative differential resistance features at low bias voltages. Remarkably, the electrical control of the spin transport in the studied systems implies a subtle distribution of the magnetisation density within the biased devices and highlights the key role of the Au(111) electrical contacts. PMID:27550064

  17. The spin Hall effect in single-crystalline gold thin films

    NASA Astrophysics Data System (ADS)

    Tian, Dai; Chen, Caigan; Wang, Hua; Jin, Xiaofeng

    2016-10-01

    The spin Hall effect has been investigated in 10-nm-thick epitaxial Au (001) single crystal films via H-pattern devices, whose minimum characteristic dimension is about 40 nm. By improving the film quality and optimizing the in-plane geometry parameters of the devices, we explicitly extract the spin Hall effect contribution from the ballistic and bypass contribution which were previously reported to be dominating the non-local voltage. Furthermore, we calculate a lower limit of the spin Hall angle of 0.08 at room temperature. Our results indicate that the giant spin Hall effect in Au thin films is dominated not by the interior defects scattering, but by the surface scattering. Besides, our results also provide an additional experimental method to determine the magnitude of spin Hall angle unambiguously. Project supported by the National Basic Research Program of China (Grant Nos. 2015CB921400 and 2011CB921802) and the National Natural Science Foundation of China (Grant Nos. 11374057, 11434003, and 11421404).

  18. Terahertz probes of magnetic field induced spin reorientation in YFeO{sub 3} single crystal

    SciTech Connect

    Lin, Xian; Jiang, Junjie; Ma, Guohong; Jin, Zuanming; Wang, Dongyang; Tian, Zhen; Han, Jiaguang; Cheng, Zhenxiang

    2015-03-02

    Using the terahertz time-domain spectroscopy, we demonstrate the spin reorientation of a canted antiferromagnetic YFeO{sub 3} single crystal, by evaluating the temperature and magnetic field dependence of resonant frequency and amplitude for the quasi-ferromagnetic (FM) and quasi-antiferromagnetic modes (AFM), a deeper insight into the dynamics of spin reorientation in rare-earth orthoferrites is established. Due to the absence of 4f-electrons in Y ion, the spin reorientation of Fe sublattices can only be induced by the applied magnetic field, rather than temperature. In agreement with the theoretical predication, the frequency of FM mode decreases with magnetic field. In addition, an obvious step of spin reorientation phase transition occurs with a relatively large applied magnetic field of 4 T. By comparison with the family members of RFeO{sub 3} (R = Y{sup 3+} or rare-earth ions), our results suggest that the chosen of R would tailor the dynamical rotation properties of Fe ions, leading to the designable spin switching in the orthoferrite antiferromagnetic systems.

  19. Mapping out spin and particle conductances of a single-mode channel with tunable interactions

    NASA Astrophysics Data System (ADS)

    Lebrat, Martin; Krinner, Sebastian; Grenier, Charles; Husmann, Dominik; Häusler, Samuel; Nakajima, Shuta; Brantut, Jean-Philippe; Esslinger, Tilman

    2016-05-01

    We study particle and spin transport in a single-mode quantum point contact, shaped by light potentials onto a charge neutral, quantum degenerate gas of 6 Li fermions with tunable interactions. The spin and particle conductances are measured as a function of chemical potential or confinement, covering weak attraction, where quantized conductance is observed, to the strongly interacting superfluid regime. Spin conductance exhibits a broad maximum when varying the chemical potential at moderate interactions, which signals the emergence of superfluidity. In contrast, the particle conductance is unexpectedly enhanced even before the gas is expected to turn into a superfluid: it shows conductance plateaus at non-universal values continuously increasing from 1/h to 4/h, as the interaction strength is increased from weak to intermediate. For strong interactions, the particle conductance plateaus disappear and the spin conductance gets suppressed, confirming the spin-insulating character of a superfluid. Our observations document the breakdown of universal conductance quantization as many-body correlations appear. This anomalous quantization is incompatible with a Fermi liquid description, shedding new light on the nature of the strongly attractive Fermi gas in the normal phase.

  20. Mechanically induced two-qubit gates and maximally entangled states for single electron spins in a carbon nanotube

    NASA Astrophysics Data System (ADS)

    Wang, Heng; Burkard, Guido

    2015-11-01

    We theoretically analyze a system where two electrons are trapped separately in two quantum dots on a suspended carbon nanotube (CNT), subject to external ac electric driving. An indirect mechanically induced coupling of two distant single electron spins is induced by the interaction between the spins and the mechanical motion of the CNT. We show that a two-qubit iswap gate and arbitrary single-qubit gates can be obtained from the intrinsic spin-orbit coupling. Combining the iswap gate and single-qubit gates, maximally entangled states of two spins can be generated in a single step by varying the frequency and the strength of the external electric driving field. The spin-phonon coupling can be turned off by electrostatically shifting the electron wave function on the nanotube.

  1. High-efficiency resonant amplification of weak magnetic fields for single spin magnetometry at room temperature.

    PubMed

    Trifunovic, Luka; Pedrocchi, Fabio L; Hoffman, Silas; Maletinsky, Patrick; Yacoby, Amir; Loss, Daniel

    2015-06-01

    Magnetic resonance techniques not only provide powerful imaging tools that have revolutionized medicine, but they have a wide spectrum of applications in other fields of science such as biology, chemistry, neuroscience and physics. However, current state-of-the-art magnetometers are unable to detect a single nuclear spin unless the tip-to-sample separation is made sufficiently small. Here, we demonstrate theoretically that by placing a ferromagnetic particle between a nitrogen-vacancy magnetometer and a target spin, the magnetometer sensitivity is improved dramatically. Using materials and techniques that are already experimentally available, our proposed set-up is sensitive enough to detect a single nuclear spin within ten milliseconds of data acquisition at room temperature. The sensitivity is practically unchanged when the ferromagnet surface to the target spin separation is smaller than the ferromagnet lateral dimensions; typically about a tenth of a micrometre. This scheme further benefits when used for nitrogen-vacancy ensemble measurements, enhancing sensitivity by an additional three orders of magnitude.

  2. High-efficiency resonant amplification of weak magnetic fields for single spin magnetometry at room temperature

    NASA Astrophysics Data System (ADS)

    Trifunovic, Luka; Pedrocchi, Fabio L.; Hoffman, Silas; Maletinsky, Patrick; Yacoby, Amir; Loss, Daniel

    2015-06-01

    Magnetic resonance techniques not only provide powerful imaging tools that have revolutionized medicine, but they have a wide spectrum of applications in other fields of science such as biology, chemistry, neuroscience and physics. However, current state-of-the-art magnetometers are unable to detect a single nuclear spin unless the tip-to-sample separation is made sufficiently small. Here, we demonstrate theoretically that by placing a ferromagnetic particle between a nitrogen-vacancy magnetometer and a target spin, the magnetometer sensitivity is improved dramatically. Using materials and techniques that are already experimentally available, our proposed set-up is sensitive enough to detect a single nuclear spin within ten milliseconds of data acquisition at room temperature. The sensitivity is practically unchanged when the ferromagnet surface to the target spin separation is smaller than the ferromagnet lateral dimensions; typically about a tenth of a micrometre. This scheme further benefits when used for nitrogen-vacancy ensemble measurements, enhancing sensitivity by an additional three orders of magnitude.

  3. Counter-diabatic driving for fast spin control in a two-electron double quantum dot.

    PubMed

    Ban, Yue; Chen, Xi

    2014-01-01

    The techniques of shortcuts to adiabaticity have been proposed to accelerate the "slow" adiabatic processes in various quantum systems with the applications in quantum information processing. In this paper, we study the counter-diabatic driving for fast adiabatic spin manipulation in a two-electron double quantum dot by designing time-dependent electric fields in the presence of spin-orbit coupling. To simplify implementation and find an alternative shortcut, we further transform the Hamiltonian in term of Lie algebra, which allows one to use a single Cartesian component of electric fields. In addition, the relation between energy and time is quantified to show the lower bound for the operation time when the maximum amplitude of electric fields is given. Finally, the fidelity is discussed with respect to noise and systematic errors, which demonstrates that the decoherence effect induced by stochastic environment can be avoided in speeded-up adiabatic control. PMID:25174453

  4. Counter-diabatic driving for fast spin control in a two-electron double quantum dot.

    PubMed

    Ban, Yue; Chen, Xi

    2014-09-01

    The techniques of shortcuts to adiabaticity have been proposed to accelerate the "slow" adiabatic processes in various quantum systems with the applications in quantum information processing. In this paper, we study the counter-diabatic driving for fast adiabatic spin manipulation in a two-electron double quantum dot by designing time-dependent electric fields in the presence of spin-orbit coupling. To simplify implementation and find an alternative shortcut, we further transform the Hamiltonian in term of Lie algebra, which allows one to use a single Cartesian component of electric fields. In addition, the relation between energy and time is quantified to show the lower bound for the operation time when the maximum amplitude of electric fields is given. Finally, the fidelity is discussed with respect to noise and systematic errors, which demonstrates that the decoherence effect induced by stochastic environment can be avoided in speeded-up adiabatic control.

  5. Electrical control of a long-lived spin qubit in a Si/SiGe quantum dot

    NASA Astrophysics Data System (ADS)

    Kawakami, Erika

    2015-03-01

    Electron spins in Si/SiGe quantum dots are one of the most promising candidates for a quantum bit for their potential to scale up and their long dephasing time. We realized coherent control of single electron spin in a single quantum dot (QD) defined in a Si/SiGe 2D electron gas. Spin rotations are achieved by applying microwave excitation to one of the gates, which oscillates the electron wave function back and forth in the gradient field produced by cobalt micromagnets fabricated near the dot. The electron spin is read out in single-shot mode via spin-to-charge conversion and a QD charge sensor. In earlier work, both the fidelity of single-spin rotations and the spin echo decay time were limited by a small splitting of the lowest two valleys. By changing the direction and magnitude of the external magnetic field as well as the gate voltages that define the dot potential, we were able to increase the valley splitting and also the difference in Zeeman splittings associated with these two valleys. This has resulted in considerable improvements in the gate fidelity and spin echo decay times. Thanks to the long intrinsic dephasing time T2* = 900 ns and Rabi frequency of 1.4 MHz, we now obtain an average single qubit gate fidelity of an electron spin in a Si/SiGe quantum dot of 99 percent, measured via randomized benchmarking. The dephasing time is extended to 70 us for the Hahn echo and up to 400 us with CPMG80. From the dynamical decoupling data, we extract the noise spectral density in the range of 30 kHz-3 MHz. We will discuss the mechanism that induces this noise and is responsible for decoherence. In parallel, we also realized electron spin resonance and coherent single-spin control by second harmonic generation, which means we can drive an electron spin at half the Larmor frequency. Finally, we observe not only single-spin transitions but also transitions whereby both the spin and the valley state are flipped. Altogether, these measurements have significantly

  6. Semiclassical spin-spin dynamics and feedback control in transport through a quantum dot

    NASA Astrophysics Data System (ADS)

    Mosshammer, Klemens; Brandes, Tobias

    2014-10-01

    We present a theory of magnetotransport through an electronic orbital, where the electron spin interacts with a (sufficiently) large external spin via an exchange interaction. Using a semiclassical approximation, we derive a set of equations of motions for the electron density matrix and the mean value of the external spin that turns out to be highly nonlinear. The dissipation via the electronic leads is implemented in terms of a quantum master equation that is combined with the nonlinear terms of the spin-spin interaction. With an anisotropic exchange coupling a variety of dynamics is generated, such as self-sustained oscillations with parametric resonances or even chaotic behavior. Within our theory we can integrate a Maxwell-demon-like closed-loop feedback scheme that is capable of transporting particles against an applied bias voltage and that can be used to implement a spin filter to generate spin-dependent oscillating currents of opposite directions.

  7. Flight investigation of stall, spin and recovery characteristics of a low-wing, single-engine, T-tail light airplane

    NASA Technical Reports Server (NTRS)

    Stough, H. P., III; Dicarlo, D. J.; Patton, J. M., Jr.

    1985-01-01

    Flight tests were performed to investigate the stall, spin, and recovery characteristics of a four-place, low-wing, single-engine, T-tail, general aviation research airplane at an aft center-of-gravity position. Most stalls resulted in roll-offs. Spins were oscillatory in roll and pitch at 43 deg angle of attack; the magnitude of the oscillations was determined by aileron position. Power, flap deflection, and landing gear position did not affect the angle of attack to the spin. Antispin rudder followed by forward wheel with ailerons neutral produced the fastest and most consistent recoveries but the initial application of recovery controls did not always stop a spin.

  8. Skyrmions and Single Spin Flips in the Odd Integer Quantized Hall Effect

    NASA Astrophysics Data System (ADS)

    Schmeller, Andreas

    1996-03-01

    For an (ideal) two-dimensional electron system in an odd integer quantized Hall state, the energy Δ needed to excite a quasiparticle pair is the sum of the Zeeman energy Sgμ_BB_tot (S is the number of flipped spins) and the many body contribution Δ_ex, where Δ_ex depends only on the perpendicular magnetic field component B_⊥. If the sample is tilted with respect to the field B_tot and B_⊥ is kept constant, the rate of change of Δ with B_tot gives S. We measure the energy gap Δ by thermally-activated magneto-transport experiments in tilted magnetic fields. We find: 1. At ν=1, where the ground state is fully spin polarized with only one spin level occupied, the lowest lying charged excitations have S >> 1. This reflects the excitation of quasiparticle pairs, with spins of up to 7/2 per particle, a value that is in good agreement with recent results of Knight shift experiments [1]. 2. In contrast we observe only single spin flips (S=1) at the higher odd integer filling factors ν=3 and 5. These results lend support to recent suggestions[2] that Skyrmions, which are topological distortions of the spin field that involve large spin values, form the lowest-lying charged excitations in the fully-polarized ν =1 quantum Hall fluid, but are energetically unfavorable with respect to single spin flips at the higher odd-integer filling factors. This work was done in collaboration with J.P. Eisenstein, L.N. Pfeiffer and K.W. West. 1: S.E. Barrett, G. Dabbagh, L.N. Pfeiffer, K.W. West, and Z. Tycko, Phys. Rev. Lett. 74, 5112 (1995). 2: S.L. Sondhi et al. Phys. Rev. B47, 16419 (1993). J. K. Jain and X. G. Wu, Phys. Rev. B49, 5085 (1994). X.-G. Wu and S.L. Sondhi, preprint (1995).

  9. Non-Markovian dynamics of a single-mode cavity strongly coupled to an inhomogeneously broadened spin ensemble

    NASA Astrophysics Data System (ADS)

    Krimer, Dmitry O.; Putz, Stefan; Majer, Johannes; Rotter, Stefan

    2014-10-01

    We study the dynamics of a spin ensemble strongly coupled to a single-mode resonator driven by external pulses. When the mean frequency of the spin ensemble is in resonance with the cavity mode, damped Rabi oscillations are found between the spin ensemble and the cavity mode which we describe very accurately, including the dephasing effect of the inhomogeneous spin broadening. We demonstrate that a precise knowledge of this broadening is crucial both for a qualitative and a quantitative understanding of the temporal spin-cavity dynamics. On this basis we show that coherent oscillations between the spin ensemble and the cavity can be enhanced by a few orders of magnitude, when driving the system with pulses that match special resonance conditions. Our theoretical approach is tested successfully with an experiment based on an ensemble of negatively charged nitrogen-vacancy centers in diamond strongly coupled to a superconducting coplanar single-mode waveguide resonator.

  10. On the Relation Between Mechanisms for Single-Transverse-SpinAsymmetries

    SciTech Connect

    Koike, Yuji; Vogelsang, Werner; Yuan, Feng

    2007-11-05

    Recent studies have shown that two widely-used mechanismsfor single-transverse-spin asymmetries based on either twist-threecontributions or on transverse-momentum-dependent (Sivers) partondistributions become identical in a kinematical regime of overlap. Thiswas demonstrated for the so-called soft-gluon-pole and hard-polecontributions to the asymmetry associated with a particular quark-gluoncorrelation function in the nucleon. In this paper, using semi-inclusivedeep inelastic scattering as an example, we extend the study to thecontributions by soft-fermion poles and by another independenttwist-three correlation function. We find that these additional termsorganize themselves in such a way as to maintain the mutual consistencyof the two mechanisms for single-spin asymmetries.

  11. A jet controlled magnetic referenced attitude control system for spinning payloads

    NASA Technical Reports Server (NTRS)

    Celmer, J. J.; Donohue, J. H.; Placanica, S. J.

    1982-01-01

    An attitude control system was designed permitting large angle acquisition and alignment of the principle axis of a spinning payload to within 1 degree of the earth's magnetic field. Signals from magnetometer and gyro sensors are fed to the control algorithm to generate commands for the jet thrusters. The algorithm contains a cross axis magnetometer signal to prevent a large angle magnetometer signal to prevent a large angle equilibrium solution. The acquisition will occur within 50 seconds from initial precession and nutation angles of 30 degrees. An electronic spin filter passes signals at spin and nutation frequencies and rejects bias signals due to sensor misalignment and principle axis offset. Describing function analysis and total analog simulation techniques were used. The flight ACS hardware was interfaced with the analog computer simulation for design and verification. The controller has flown on four successful missions.

  12. Spin glass in semiconducting KFe1.05Ag0.88Te2 single crystals

    DOE PAGES

    Ryu, H.; Lei, H.; Klobes, B.; Warren, J. B.; Hermann, R. P.; Petrovic, C.

    2015-05-26

    We report discovery of KFe1.05Ag0.88Te2 single crystals with semiconducting spin glass ground state. Composition and structure analysis suggest nearly stoichiometric I4/mmm space group but allow for the existence of vacancies, absent in long range semiconducting antiferromagnet KFe1.05Ag0.88Te2. The subtle change in stoichometry in Fe/Ag sublattice changes magnetic ground state but not conductivity, giving further insight into the semiconducting gap mechanism.

  13. Accelerated 2D magnetic resonance spectroscopy of single spins using matrix completion

    PubMed Central

    Scheuer, Jochen; Stark, Alexander; Kost, Matthias; Plenio, Martin B.; Naydenov, Boris; Jelezko, Fedor

    2015-01-01

    Two dimensional nuclear magnetic resonance (NMR) spectroscopy is one of the major tools for analysing the chemical structure of organic molecules and proteins. Despite its power, this technique requires long measurement times, which, particularly in the recently emerging diamond based single molecule NMR, limits its application to stable samples. Here we demonstrate a method which allows to obtain the spectrum by collecting only a small fraction of the experimental data. Our method is based on matrix completion which can recover the full spectral information from randomly sampled data points. We confirm experimentally the applicability of this technique by performing two dimensional electron spin echo envelope modulation (ESEEM) experiments on a two spin system consisting of a single nitrogen vacancy (NV) centre in diamond coupled to a single 13C nuclear spin. The signal to noise ratio of the recovered 2D spectrum is compared to the Fourier transform of randomly subsampled data, where we observe a strong suppression of the noise when the matrix completion algorithm is applied. We show that the peaks in the spectrum can be obtained with only 10% of the total number of the data points. We believe that our results reported here can find an application in all types of two dimensional spectroscopy, as long as the measured matrices have a low rank. PMID:26631593

  14. g tensor modulation resonance and single-spin manipulation in semiconductor quantum dots

    NASA Astrophysics Data System (ADS)

    Pingenot, Joseph

    2005-03-01

    We explore how electric fields can be used to drive single spin resonance in quantum dots without AC magnetic fields. We calculate the g tensor for a single electron in a semiconductor quantum dot as a function of electric field along the growth direction of the dot. The calculations are based on an eight-band envelope-function formalism[1]. The growth-direction g factor is relatively insensitive to this electric field, but for InAs/GaAs dots with transition energies around 1.2 eV the in-plane g factor changes by 20% for an electric field of 150kV/cm. For a DC magnetic field oriented at 45 degrees to the growth direction the spin precession axis for an electron changes by 6 degrees from zero electric field to 150 kV/cm. Thus an AC pseudo-magnetic field almost 10% the size of the DC magnetic field can be generated. This is sufficient to drive g-tensor modulation resonance[2] in the dot and perform single-spin manipulation. 1. C. E. Pryor and M. E. Flatt'e, cond-mat/0410678. 2. Y. Kato, et al., Science 299, 1201 (2003).

  15. Single-Spin Transverse Asymmetry in Neutral Pion Production at PHENIX

    NASA Astrophysics Data System (ADS)

    Aidala, Christine

    2003-10-01

    The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) inaugurated its operation as the first polarized proton collider during the 2001-2002 run. >From the data collected in this run, the PHENIX experiment measured the single-spin transverse asymmetry (A_N) for neutral pion production at x_F ˜0 over a pT range of 1.0 to ˜8.0 GeV/c from polarized proton-proton interactions at a center of mass energy (√s) of 200 GeV. Interest in these measurements arises from the observation of large ( ˜30%) single-spin transverse asymmetries in pp_arrowarrowπ X at forward angles by the E704 collaboration at Fermilab (√s = 19.4GeV) and single-spin, azimuthal asymmetries in semi-inclusive deep-inelastic scattering by the HERMES collaboration at DESY. Such large asymmetries were initially surprising because, at leading-order twist, pQCD predicts only small effects. Recently it has been realized that large asymmetries may be produced by initial-state effects (e.g. the Sivers' effect), final-state effects (e.g. the Collin's effect), higher-twist contributions, or a combination of the three. In this talk, we will report on the results of this experimental effort.

  16. Cavity Exciton-Polariton mediated, Single-Shot Quantum Non-Demolition measurement of a Quantum Dot Electron Spin

    NASA Astrophysics Data System (ADS)

    Puri, Shruti; McMahon, Peter; Yamamoto, Yoshihisa

    2014-03-01

    The quantum non-demolition (QND) measurement of a single electron spin is of great importance in measurement-based quantum computing schemes. The current single-shot readout demonstrations exhibit substantial spin-flip backaction. We propose a QND readout scheme for quantum dot (QD) electron spins in Faraday geometry, which differs from previous proposals and implementations in that it relies on a novel physical mechanism: the spin-dependent Coulomb exchange interaction between a QD spin and optically-excited quantum well (QW) microcavity exciton-polaritons. The Coulomb exchange interaction causes a spin-dependent shift in the resonance energy of the polarized polaritons, thus causing the phase and intensity response of left circularly polarized light to be different to that of the right circularly polarized light. As a result the QD electron's spin can be inferred from the response to a linearly polarized probe. We show that by a careful design of the system, any spin-flip backaction can be eliminated and a QND measurement of the QD electron spin can be performed within a few 10's of nanoseconds with fidelity 99:95%. This improves upon current optical QD spin readout techniques across multiple metrics, including fidelity, speed and scalability. National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430, Japan.

  17. Long spin lifetime and large barrier polarisation in single electron transport through a CoFe nanoparticle

    NASA Astrophysics Data System (ADS)

    Temple, R. C.; McLaren, M.; Brydson, R. M. D.; Hickey, B. J.; Marrows, C. H.

    2016-06-01

    We have investigated single electron spin transport in individual single crystal bcc Co30Fe70 nanoparticles using scanning tunnelling microscopy with a standard tungsten tip. Particles were deposited using a gas-aggregation nanoparticle source and individually addressed as asymmetric double tunnel junctions with both a vacuum and a MgO tunnel barrier. Spectroscopy measurements on the particles show a Coulomb staircase that is correlated with the measured particle size. Field emission tunnelling effects are incorporated into standard single electron theory to model the data. This formalism allows spin-dependent parameters to be determined even though the tip is not spin-polarised. The barrier spin polarisation is very high, in excess of 84%. By variation of the resistance, several orders of magnitude of the system timescale are probed, enabling us to determine the spin relaxation time on the island. It is found to be close to 10 μs, a value much longer than previously reported.

  18. Long spin lifetime and large barrier polarisation in single electron transport through a CoFe nanoparticle

    PubMed Central

    Temple, R. C.; McLaren, M.; Brydson, R. M. D.; Hickey, B. J.; Marrows, C. H.

    2016-01-01

    We have investigated single electron spin transport in individual single crystal bcc Co30Fe70 nanoparticles using scanning tunnelling microscopy with a standard tungsten tip. Particles were deposited using a gas-aggregation nanoparticle source and individually addressed as asymmetric double tunnel junctions with both a vacuum and a MgO tunnel barrier. Spectroscopy measurements on the particles show a Coulomb staircase that is correlated with the measured particle size. Field emission tunnelling effects are incorporated into standard single electron theory to model the data. This formalism allows spin-dependent parameters to be determined even though the tip is not spin-polarised. The barrier spin polarisation is very high, in excess of 84%. By variation of the resistance, several orders of magnitude of the system timescale are probed, enabling us to determine the spin relaxation time on the island. It is found to be close to 10 μs, a value much longer than previously reported. PMID:27329575

  19. Long spin lifetime and large barrier polarisation in single electron transport through a CoFe nanoparticle.

    PubMed

    Temple, R C; McLaren, M; Brydson, R M D; Hickey, B J; Marrows, C H

    2016-01-01

    We have investigated single electron spin transport in individual single crystal bcc Co30Fe70 nanoparticles using scanning tunnelling microscopy with a standard tungsten tip. Particles were deposited using a gas-aggregation nanoparticle source and individually addressed as asymmetric double tunnel junctions with both a vacuum and a MgO tunnel barrier. Spectroscopy measurements on the particles show a Coulomb staircase that is correlated with the measured particle size. Field emission tunnelling effects are incorporated into standard single electron theory to model the data. This formalism allows spin-dependent parameters to be determined even though the tip is not spin-polarised. The barrier spin polarisation is very high, in excess of 84%. By variation of the resistance, several orders of magnitude of the system timescale are probed, enabling us to determine the spin relaxation time on the island. It is found to be close to 10 μs, a value much longer than previously reported. PMID:27329575

  20. Spin-tunnel investigation of the spinning characteristics of typical single-engine general aviation airplane designs. 2: Low-wing model A; tail parachute diameter and canopy distance for emergency spin recovery

    NASA Technical Reports Server (NTRS)

    Burk, S. M., Jr.; Bowman, J. S., Jr.; White, W. L.

    1977-01-01

    A spin tunnel study is reported on a scale model of a research airplane typical of low-wing, single-engine, light general aviation airplanes to determine the tail parachute diameter and canopy distance (riser length plus suspension-line length) required for energency spin recovery. Nine tail configurations were tested, resulting in a wide range of developed spin conditions, including steep spins and flat spins. The results indicate that the full-scale parachute diameter required for satisfactory recovery from the most critical conditions investigated is about 3.2 m and that the canopy distance, which was found to be critical for flat spins, should be between 4.6 and 6.1 m.

  1. Addressing a single spin in diamond with a macroscopic dielectric microwave cavity

    SciTech Connect

    Le Floch, J.-M.; Tobar, M. E.; Bradac, C.; Nand, N.; Volz, T.; Castelletto, S.

    2014-09-29

    We present a technique for addressing single nitrogen-vacancy (NV) center spins in diamond over macroscopic distances using a tunable dielectric microwave cavity. We demonstrate optically detected magnetic resonance (ODMR) for a single negatively charged NV center (NV{sup –}) in a nanodiamond (ND) located directly under the macroscopic microwave cavity. By moving the cavity relative to the ND, we record the ODMR signal as a function of position, mapping out the distribution of the cavity magnetic field along one axis. In addition, we argue that our system could be used to determine the orientation of the NV{sup –} major axis in a straightforward manner.

  2. Process Dependent Sivers Function and Implication for Single Spin Asymmetry in Inclusive Hadron Production

    SciTech Connect

    Leonard Gamberg, Zhong-Bo Kang

    2011-01-01

    We study the single transverse spin asymmetries in the single inclusive particle production within the framework of the generalized parton model (GPM). By carefully analyzing the initial- and final-state interactions, we include the process-dependence of the Sivers functions into the GPM formalism. The modified GPM formalism has a close connection with the collinear twist-3 approach. Within the new formalism, we make predictions for inclusive {pi}{sup 0} and direct photon productions at RHIC energies. We find the predictions are opposite to those in the conventional GPM approach.

  3. Spin Dynamics of a Single Mn Ion in a CdTe/(Cd, Mg, Zn)Te Quantum Dot

    SciTech Connect

    Goryca, Mateusz; Kossacki, Piotr; Golnik, Andrzej; Kazimierczuk, Tomasz; Nawrocki, Michal; Wojnar, Piotr

    2010-01-04

    The spin dynamics of a single Mn ion confined in a CdTe/(Cd, Mg, Zn)Te quantum dot is determined by measurements of photon correlation of photoluminescence. The characteristic time of spin flip is a few nanoseconds and strongly depends on the excitation power.

  4. Parametric analysis of plastic strain and force distribution in single pass metal spinning

    SciTech Connect

    Choudhary, Shashank E-mail: mohantejesh93@gmail.com E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Tejesh, Chiruvolu Mohan E-mail: mohantejesh93@gmail.com E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Regalla, Srinivasa Prakash E-mail: mohantejesh93@gmail.com E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Suresh, Kurra E-mail: mohantejesh93@gmail.com E-mail: ksuresh@hyderabad.bits-pilani.ac.in

    2013-12-16

    Metal spinning also known as spin forming is one of the sheet metal working processes by which an axis-symmetric part can be formed from a flat sheet metal blank. Parts are produced by pressing a blunt edged tool or roller on to the blank which in turn is mounted on a rotating mandrel. This paper discusses about the setting up a 3-D finite element simulation of single pass metal spinning in LS-Dyna. Four parameters were considered namely blank thickness, roller nose radius, feed ratio and mandrel speed and the variation in forces and plastic strain were analysed using the full-factorial design of experiments (DOE) method of simulation experiments. For some of these DOE runs, physical experiments on extra deep drawing (EDD) sheet metal were carried out using En31 tool on a lathe machine. Simulation results are able to predict the zone of unsafe thinning in the sheet and high forming forces that are hint to the necessity for less-expensive and semi-automated machine tools to help the household and small scale spinning workers widely prevalent in India.

  5. Spin excitations in a single La2CuO4 layer.

    PubMed

    Dean, M P M; Springell, R S; Monney, C; Zhou, K J; Pereiro, J; Božović, I; Dalla Piazza, B; Rønnow, H M; Morenzoni, E; van den Brink, J; Schmitt, T; Hill, J P

    2012-10-01

    Cuprates and other high-temperature superconductors consist of two-dimensional layers that are crucial to their properties. The dynamics of the quantum spins in these layers lie at the heart of the mystery of the cuprates. In bulk cuprates such as La(2)CuO(4), the presence of a weak coupling between the two-dimensional layers stabilizes a three-dimensional magnetic order up to high temperatures. In a truly two-dimensional system however, thermal spin fluctuations melt long-range order at any finite temperature. Here, we measure the spin response of isolated layers of La(2)CuO(4) that are only one-unit-cell-thick. We show that coherent magnetic excitations, magnons, known from the bulk order, persist even in a single layer of La(2)CuO(4), with no evidence for more complex correlations such as resonating valence bond correlations. These magnons are, therefore, well described by spin-wave theory (SWT). On the other hand, we also observe a high-energy magnetic continuum in the isotropic magnetic response that is not well described by two-magnon SWT, or indeed any existing theories. PMID:22941330

  6. Freezing motion-induced dephasing for single spin-state stored in atomic ensemble

    NASA Astrophysics Data System (ADS)

    Jiang, Yan; Jun, Rui; Bao, Xiao-Hui; Pan, Jian-Wei

    2016-05-01

    Atomic-ensemble quantum memories are well considered as a promising approach of long-distance quantum communication and computation for strong light-matter interaction. While the storage lifetime is limited by the motion-induced dephasing. Spin-echo technique, increasing wavelength of spin-wave, as well as optical lattice are used commonly to overcome this dephasing process. However, these techniques either need extremely high fidelity of echo pulse or put high restriction on filter and experimental complexity. In this poster, we demonstrate a convenient technique to freeze the motion-induced dephasing without population inversion and can be used in large storage angles. Combined with ``clock states'', the lifetime is extended by one order of magnitude to the limit of the thermal expansion. What's more, high non-classical correlation above 20 has been achieved to guarantee the memory in quantum regime.By making the advance from passive engineering to coherent manipulation of single spin-wave states, our work enriches the experimental toolbox of harnessing atomic ensembles for high-performance quantum memories, especially for holographic quantum memories where many spin-waves with different wave-vectors are used.

  7. Sensing of single nuclear spins in random thermal motion with proximate nitrogen-vacancy centers

    NASA Astrophysics Data System (ADS)

    Bruderer, M.; Fernández-Acebal, P.; Aurich, R.; Plenio, M. B.

    2016-03-01

    Nitrogen-vacancy (NV) centers in diamond have emerged as valuable tools for sensing and polarizing spins. Motivated by potential applications in chemistry, biology, and medicine, we show that NV-based sensors are capable of detecting single spin targets even if they undergo diffusive motion in an ambient thermal environment. Focusing on experimentally relevant diffusion regimes, we derive an effective model for the NV-target interaction, where parameters entering the model are obtained from numerical simulations of the target motion. The practicality of our approach is demonstrated by analyzing two realistic experimental scenarios: (i) time-resolved sensing of a fluorine nuclear spin bound to an N-heterocyclic carbene-ruthenium (NHC-Ru) catalyst that is immobilized on the diamond surface and (ii) detection of an electron spin label by an NV center in a nanodiamond, both attached to a vibrating chemokine receptor in thermal motion. We find in particular that the detachment of a fluorine target from the NHC-Ru carrier molecule can be monitored with a time resolution of a few seconds.

  8. Bistability and steady-state spin squeezing in diamond nanostructures controlled by a nanomechanical resonator

    NASA Astrophysics Data System (ADS)

    Ma, Yong-Hong; Zhang, Xue-Feng; Song, Jie; Wu, E.

    2016-06-01

    As the quantum states of nitrogen vacancy (NV) center can be coherently manipulated and obtained at room temperature, it is important to generate steady-state spin squeezing in spin qubits associated with NV impurities in diamond. With this task we consider a new type of a hybrid magneto-nano-electromechanical resonator, the functionality of which is based on a magnetic-field induced deflection of an appropriate cantilever that oscillates between NV spins in diamond. We show that there is bistability and spin squeezing state due to the presence of the microwave field, despite the damping from mechanical damping. Moreover, we find that bistability and spin squeezing can be controlled by the microwave field and the parameter Vz. Our scheme may have the potential application on spin clocks, magnetometers, and other measurements based on spin-spin system in diamond nanostructures.

  9. Development of a Small-spin-axis Controller and Its Application to a Solar Sail Subpayload Satellite

    NASA Astrophysics Data System (ADS)

    Saiki, Takanao; Nakaya, Koji; Yamamoto, Takayuki; Tsuda, Yuichi; Mori, Osamu; Kawaguchi, Jun'ichiro

    The instruments and actuators in the attitude control system of small spacecraft are restricted in weight and space, and need to be reduced in weight and size. The rhumb line control strategy is one of the most popular schemes in reorientation of spin-stabilized spacecraft, since it requires only a spin sun sensor and a single axis reaction control system. By being combined with active nutation control, rhumb line control can reorient the spin axis of the spacecraft to any direction. To verify the control strategy, we manufactured an attitude controller and demonstration experiments were conducted using a motion table at ISAS/JAXA. This paper reviews the configuration of the controller and the outlines of the experiments, and evaluates the control performance. The same type of controller was installed in the Solar Sail Subpayload Satellite (SSSAT) launched in September 2006. An attitude control experiment in orbit was not conducted because of trouble with the satellite, but new control logic for the SSSAT was implemented for the attitude controller. This paper also reviews the control logic of the SSSAT.

  10. Electrical control of a long-lived spin qubit in a Si/SiGe quantum dot.

    PubMed

    Kawakami, E; Scarlino, P; Ward, D R; Braakman, F R; Savage, D E; Lagally, M G; Friesen, Mark; Coppersmith, S N; Eriksson, M A; Vandersypen, L M K

    2014-09-01

    Nanofabricated quantum bits permit large-scale integration but usually suffer from short coherence times due to interactions with their solid-state environment. The outstanding challenge is to engineer the environment so that it minimally affects the qubit, but still allows qubit control and scalability. Here, we demonstrate a long-lived single-electron spin qubit in a Si/SiGe quantum dot with all-electrical two-axis control. The spin is driven by resonant microwave electric fields in a transverse magnetic field gradient from a local micromagnet, and the spin state is read out in the single-shot mode. Electron spin resonance occurs at two closely spaced frequencies, which we attribute to two valley states. Thanks to the weak hyperfine coupling in silicon, a Ramsey decay timescale of 1 μs is observed, almost two orders of magnitude longer than the intrinsic timescales in GaAs quantum dots, whereas gate operation times are comparable to those reported in GaAs. The spin echo decay time is ~40 μs, both with one and four echo pulses, possibly limited by intervalley scattering. These advances strongly improve the prospects for quantum information processing based on quantum dots. PMID:25108810

  11. Quantum electronics. Probing Johnson noise and ballistic transport in normal metals with a single-spin qubit.

    PubMed

    Kolkowitz, S; Safira, A; High, A A; Devlin, R C; Choi, S; Unterreithmeier, Q P; Patterson, D; Zibrov, A S; Manucharyan, V E; Park, H; Lukin, M D

    2015-03-01

    Thermally induced electrical currents, known as Johnson noise, cause fluctuating electric and magnetic fields in proximity to a conductor. These fluctuations are intrinsically related to the conductivity of the metal. We use single-spin qubits associated with nitrogen-vacancy centers in diamond to probe Johnson noise in the vicinity of conductive silver films. Measurements of polycrystalline silver films over a range of distances (20 to 200 nanometers) and temperatures (10 to 300 kelvin) are consistent with the classically expected behavior of the magnetic fluctuations. However, we find that Johnson noise is markedly suppressed next to single-crystal films, indicative of a substantial deviation from Ohm's law at length scales below the electron mean free path. Our results are consistent with a generalized model that accounts for the ballistic motion of electrons in the metal, indicating that under the appropriate conditions, nearby electrodes may be used for controlling nanoscale optoelectronic, atomic, and solid-state quantum systems.

  12. Optimized quantum sensing with a single electron spin using real-time adaptive measurements

    NASA Astrophysics Data System (ADS)

    Bonato, C.; Blok, M. S.; Dinani, H. T.; Berry, D. W.; Markham, M. L.; Twitchen, D. J.; Hanson, R.

    2016-03-01

    Quantum sensors based on single solid-state spins promise a unique combination of sensitivity and spatial resolution. The key challenge in sensing is to achieve minimum estimation uncertainty within a given time and with high dynamic range. Adaptive strategies have been proposed to achieve optimal performance, but their implementation in solid-state systems has been hindered by the demanding experimental requirements. Here, we realize adaptive d.c. sensing by combining single-shot readout of an electron spin in diamond with fast feedback. By adapting the spin readout basis in real time based on previous outcomes, we demonstrate a sensitivity in Ramsey interferometry surpassing the standard measurement limit. Furthermore, we find by simulations and experiments that adaptive protocols offer a distinctive advantage over the best known non-adaptive protocols when overhead and limited estimation time are taken into account. Using an optimized adaptive protocol we achieve a magnetic field sensitivity of 6.1 ± 1.7 nT Hz-1/2 over a wide range of 1.78 mT. These results open up a new class of experiments for solid-state sensors in which real-time knowledge of the measurement history is exploited to obtain optimal performance.

  13. Ultrafast spin-polarization control of Dirac fermions in topological insulators

    NASA Astrophysics Data System (ADS)

    Sánchez-Barriga, J.; Golias, E.; Varykhalov, A.; Braun, J.; Yashina, L. V.; Schumann, R.; Minár, J.; Ebert, H.; Kornilov, O.; Rader, O.

    2016-04-01

    Three-dimensional topological insulators (TIs) are characterized by spin-polarized Dirac-cone surface states that are protected from backscattering by time-reversal symmetry. Control of the spin polarization of topological surface states (TSSs) using femtosecond light pulses opens novel perspectives for the generation and manipulation of dissipationless surface spin currents on ultrafast time scales. Using time-, spin-, and angle-resolved spectroscopy, we directly monitor the ultrafast response of the spin polarization of photoexcited TSSs to circularly polarized femtosecond pulses of infrared light. We achieve all-optical switching of the transient out-of-plane spin polarization, which relaxes in about 1.2 ps. Our observations establish the feasibility of ultrafast optical control of spin-polarized Dirac fermions in TIs and pave the way for optospintronic applications at ultimate speeds.

  14. Polarization control at spin-driven ferroelectric domain walls

    NASA Astrophysics Data System (ADS)

    Leo, Naëmi; Bergman, Anders; Cano, Andres; Poudel, Narayan; Lorenz, Bernd; Fiebig, Manfred; Meier, Dennis

    2015-04-01

    Unusual electronic states arise at ferroelectric domain walls due to the local symmetry reduction, strain gradients and electrostatics. This particularly applies to improper ferroelectrics, where the polarization is induced by a structural or magnetic order parameter. Because of the subordinate nature of the polarization, the rigid mechanical and electrostatic boundary conditions that constrain domain walls in proper ferroics are lifted. Here we show that spin-driven ferroelectricity promotes the emergence of charged domain walls. This provides new degrees of flexibility for controlling domain-wall charges in a deterministic and reversible process. We create and position a domain wall by an electric field in Mn0.95Co0.05WO4. With a magnetic field we then rotate the polarization and convert neutral into charged domain walls, while its magnetic properties peg the wall to its location. Using atomistic Landau-Lifshitz-Gilbert simulations we quantify the polarization changes across the two wall types and highlight their general occurrence.

  15. Polarization control at spin-driven ferroelectric domain walls.

    PubMed

    Leo, Naëmi; Bergman, Anders; Cano, Andres; Poudel, Narayan; Lorenz, Bernd; Fiebig, Manfred; Meier, Dennis

    2015-04-14

    Unusual electronic states arise at ferroelectric domain walls due to the local symmetry reduction, strain gradients and electrostatics. This particularly applies to improper ferroelectrics, where the polarization is induced by a structural or magnetic order parameter. Because of the subordinate nature of the polarization, the rigid mechanical and electrostatic boundary conditions that constrain domain walls in proper ferroics are lifted. Here we show that spin-driven ferroelectricity promotes the emergence of charged domain walls. This provides new degrees of flexibility for controlling domain-wall charges in a deterministic and reversible process. We create and position a domain wall by an electric field in Mn0.95Co0.05WO4. With a magnetic field we then rotate the polarization and convert neutral into charged domain walls, while its magnetic properties peg the wall to its location. Using atomistic Landau-Lifshitz-Gilbert simulations we quantify the polarization changes across the two wall types and highlight their general occurrence.

  16. Separation of the inverse spin Hall effect and anomalous Nernst effect in a single ferromagnetic metal using on-chip spin Seebeck devices

    NASA Astrophysics Data System (ADS)

    Wu, Stephen; Hoffman, Jason; Pearson, John; Bhattacharya, Anand

    The longitudinal spin Seebeck effect is measured on the ferromagnetic insulator Fe3O4 with the ferromagnetic metal Co0.2Fe0.6B0.2 (CoFeB) as the spin detector in a micro-patterned device structure using an on-chip heater. By using a non-magnetic spacer material between the two materials (Ti), it is possible to decouple the two ferromagnetic materials and directly observe pure spin flow from Fe3O4 into CoFeB. It is shown, that in a single ferromagnetic metal the inverse spin Hall effect (ISHE) and anomalous Nernst effect (ANE) can occur simultaneously with opposite polarity. Using this and the large difference in the coercive fields between the two magnets, it is possible to unambiguously separate the contributions of the spin Seebeck effect from the ANE and observe the degree to which each effect contributes to the total response within a single experiment. Additionally, by using the spin detector layer as a thermometer, an accurate value for the thermal gradient across the device can be measured. These results match well with thermal simulations of our device structure. All authors acknowledge support of the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), Materials Sciences and Engineering Division.

  17. Dynamics and control of a single-line maneuverable kite

    NASA Astrophysics Data System (ADS)

    Donnelly, Christopher Joseph

    Through simulation, an automated control system for a single-line maneuverable kite is developed for application in kite wind energy production. The kite used in this study is a small, tension-controlled, single-line kite, commonly known as a fighter kite. These kites have a simple design, but flying them requires complex control of line tension and visual input. At low tether tension, the kite is unstable; spinning about the tether. Increasing tension in the tether causes the kite to deform and fly in the direction it was facing. Experienced fliers can produce intricate maneuvers and often participate in competitions with other fliers. A simplified physical and behavioral numeric simulation of the kite's dynamics was created and shown to closely approximate the actual kite's flight characteristics. This model was used to develop successful control algorithms for autonomous flight. Information of the kite's state and orientation used by the controller was gradually reduced to that which is physically measurable from the ground. An experimental test rig was designed and constructed for future testing in real wind conditions.

  18. Controlling electric and magnetic currents in artificial spin ice (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Branford, Will R.

    2015-09-01

    I will discuss the collective properties of arrays of single domain nanomagnets called Artificial Spin Ice.1 The shape of each nanomagnet controls the magnetic anisotropy and the elements are closely spaced so dipolar interactions are important. The honeycomb lattice geometry prevents the satisfaction of all dipole interactions. Here I will show direct magnetic imaging studies of magnetic charge flow.2 The magnetic charge is carried by transverse domain walls and the chirality of the domain wall is found to control the direction of propagation.3,4 Injection of domain walls within the arrays with local fields is also explored.5 References 1 Branford, W. R., Ladak, S., Read, D. E., Zeissler, K. and Cohen, L. F. Emerging Chirality in Artificial Spin Ice. Science 335, 1597-1600, (2012). 2 Ladak, S., Read, D. E., Perkins, G. K., Cohen, L. F. and Branford, W. R. Direct observation of magnetic monopole defects in an artificial spin-ice system. Nature Physics 6, 359-363, (2010). 3 Burn, D. M., Chadha, M., Walton, S. K. and Branford, W. R. Dynamic interaction between domain walls and nanowire vertices. Phys. Rev. B 90, 144414, (2014). 4 Zeissler, K., Walton, S. K., Ladak, S., Read, D. E., Tyliszczak, T., Cohen, L. F. and Branford, W. R. The non-random walk of chiral magnetic charge carriers in artificial spin ice. Sci Rep-Uk 3, 1252, (2013). 5 Pushp, A., Phung, T., Rettner, C., Hughes, B. P., Yang, S. H., Thomas, L. and Parkin, S. S. P. Domain wall trajectory determined by its fractional topological edge defects. Nature Physics 9, 505-511, (2013).

  19. Control of the spin to charge conversion using the inverse Rashba-Edelstein effect

    SciTech Connect

    Sangiao, S.; De Teresa, J. M.; Morellon, L.; Martinez-Velarte, M. C.; Lucas, I.; Viret, M.

    2015-04-27

    We show here that using spin orbit coupling interactions at a metallic interface it is possible to control the sign of the spin to charge conversion in a spin pumping experiment. Using the intrinsic symmetry of the “Inverse Rashba Edelstein Effect” (IREE) in a Bi/Ag interface, the charge current changes sign when reversing the order of the Ag and Bi stacking. This confirms the IREE nature of the conversion of spin into charge in these interfaces and opens the way to tailoring the spin sensing voltage by an appropriate trilayer sequence.

  20. Alignment, rotation, and spinning of single plasmonic nanoparticles and nanowires using polarization dependent optical forces.

    PubMed

    Tong, Lianming; Miljković, Vladimir D; Käll, Mikael

    2010-01-01

    We demonstrate optical alignment and rotation of individual plasmonic nanostructures with lengths from tens of nanometers to several micrometers using a single beam of linearly polarized near-infrared laser light. Silver nanorods and dimers of gold nanoparticles align parallel to the laser polarization because of the high long-axis dipole polarizability. Silver nanowires, in contrast, spontaneously turn perpendicular to the incident polarization and predominantly attach at the wire ends, in agreement with electrodynamics simulations. Wires, rods, and dimers all rotate if the incident polarization is turned. In the case of nanowires, we demonstrate spinning at an angular frequency of approximately 1 Hz due to transfer of spin angular momentum from circularly polarized light. PMID:20030391

  1. Single laser pulse induces spin state transition within the hysteresis loop of an Iron compound

    NASA Astrophysics Data System (ADS)

    Freysz, E.; Montant, S.; Létard, S.; Létard, J.-F.

    2004-08-01

    Within the thermal hysteresis loop of the [Fe(PM-BiA) 2(NCS) 2] compound, a single laser pulse of 14 mJ cm -2 induces a photo-conversion from the low spin (LS, S = 0) to the high spin (HS, S = 2) state of the Fe 2+ metallic center. The temporal dynamic of this phenomena indicates that the system is firstly photo-excited into the HS state and then slowly relaxes to a mixture of HS/LS state. Subsequent laser pulses do not affect the HS/LS ratio. The system can be brought back to its initial LS state by adjusting the temperature of the compound. A simple model accounts qualitatively for the observed phenomenon.

  2. 19F nuclear spin relaxation and spin diffusion effects in the single-ion magnet LiYF4:Ho3+

    NASA Astrophysics Data System (ADS)

    Malkin, B. Z.; Vanyunin, M. V.; Graf, M. J.; Lago, J.; Borsa, F.; Lascialfari, A.; Tkachuk, A. M.; Barbara, B.

    2008-11-01

    Temperature and magnetic field dependences of the 19F nuclear spin-lattice relaxation in a single crystal of LiYF4 doped with holmium are described by an approach based on a detailed consideration of the magnetic dipole-dipole interactions between nuclei and impurity paramagnetic ions and nuclear spin diffusion processes. The observed non-exponential long time recovery of the nuclear magnetization after saturation at intermediate temperatures is in agreement with predictions of the spin-diffusion theory in a case of the diffusion limited relaxation. At avoided level crossings in the spectrum of electron-nuclear states of Ho3 + ions, rates of nuclear spin-lattice relaxation increase due to quasi-resonant energy exchange between nuclei and paramagnetic ions in contrast to the predominant role played by electronic cross-relaxation processes in the low-frequency ac-susceptibility.

  3. Rare-Earth Triangular Lattice Spin Liquid: A Single-Crystal Study of YbMgGaO4.

    PubMed

    Li, Yuesheng; Chen, Gang; Tong, Wei; Pi, Li; Liu, Juanjuan; Yang, Zhaorong; Wang, Xiaoqun; Zhang, Qingming

    2015-10-16

    YbMgGaO4, a structurally perfect two-dimensional triangular lattice with an odd number of electrons per unit cell and spin-orbit entangled effective spin-1/2 local moments for the Yb(3+) ions, is likely to experimentally realize the quantum spin liquid ground state. We report the first experimental characterization of single-crystal YbMgGaO4 samples. Because of the spin-orbit entanglement, the interaction between the neighboring Yb(3+) moments depends on the bond orientations and is highly anisotropic in the spin space. We carry out thermodynamic and the electron spin resonance measurements to confirm the anisotropic nature of the spin interaction as well as to quantitatively determine the couplings. Our result is a first step towards the theoretical understanding of the possible quantum spin liquid ground state in this system and sheds new light on the search for quantum spin liquids in strong spin-orbit coupled insulators. PMID:26550899

  4. Polytype control of spin qubits in silicon carbide

    PubMed Central

    Falk, Abram L.; Buckley, Bob B.; Calusine, Greg; Koehl, William F.; Dobrovitski, Viatcheslav V.; Politi, Alberto; Zorman, Christian A.; Feng, Philip X.-L.; Awschalom, David D.

    2013-01-01

    Crystal defects can confine isolated electronic spins and are promising candidates for solid-state quantum information. Alongside research focusing on nitrogen-vacancy centres in diamond, an alternative strategy seeks to identify new spin systems with an expanded set of technological capabilities, a materials-driven approach that could ultimately lead to ‘designer’ spins with tailored properties. Here we show that the 4H, 6H and 3C polytypes of SiC all host coherent and optically addressable defect spin states, including states in all three with room-temperature quantum coherence. The prevalence of this spin coherence shows that crystal polymorphism can be a degree of freedom for engineering spin qubits. Long spin coherence times allow us to use double electron–electron resonance to measure magnetic dipole interactions between spin ensembles in inequivalent lattice sites of the same crystal. Together with the distinct optical and spin transition energies of such inequivalent states, these interactions provide a route to dipole-coupled networks of separately addressable spins. PMID:23652007

  5. Analytic derivative couplings for spin-flip configuration interaction singles and spin-flip time-dependent density functional theory

    SciTech Connect

    Zhang, Xing; Herbert, John M.

    2014-08-14

    We revisit the calculation of analytic derivative couplings for configuration interaction singles (CIS), and derive and implement these couplings for its spin-flip variant for the first time. Our algorithm is closely related to the CIS analytic energy gradient algorithm and should be straightforward to implement in any quantum chemistry code that has CIS analytic energy gradients. The additional cost of evaluating the derivative couplings is small in comparison to the cost of evaluating the gradients for the two electronic states in question. Incorporation of an exchange-correlation term provides an ad hoc extension of this formalism to time-dependent density functional theory within the Tamm-Dancoff approximation, without the need to invoke quadratic response theory or evaluate third derivatives of the exchange-correlation functional. Application to several different conical intersections in ethylene demonstrates that minimum-energy crossing points along conical seams can be located at substantially reduced cost when analytic derivative couplings are employed, as compared to use of a branching-plane updating algorithm that does not require these couplings. Application to H{sub 3} near its D{sub 3h} geometry demonstrates that correct topology is obtained in the vicinity of a conical intersection involving a degenerate ground state.

  6. Electron spin resonance microscopy applied to the study of controlled drug release.

    PubMed

    Blank, Aharon; Freed, Jack H; Kumar, Naraharisetti Pavan; Wang, Chi-Hwa

    2006-03-10

    We describe our recent developments towards 3D micron-scale imaging capability, based on electron spin resonance (ESR), and its application to the study of controlled release. The method, termed ESR microscopy (ESRM), is an extension of the conventional "millimeter-scale" ESR imaging technique. It employs paramagnetic molecules (such as stable radicals or spin-labeled drugs) and may enable one to obtain accurate 3D spatially resolved information about the drug concentration, its self-diffusion tensor, rotational correlation time and the pH in the release matrix. Theoretical calculations, along with initial experimental results, suggest that a 3D resolution of approximately 1 microm is feasible with this method. Here we were able to image successfully a high spin concentration sample with a resolution of approximately 3 x 3 x 8 microm and subsequently study a single approximately 120 microm biodegradable microsphere, internalized with a dilute solution of trityl radical, with a resolution of approximately 12.7 x 13.2 x 26 microm. Analysis of the microsphere ESR imaging data revealed a likely increase in the viscosity inside the sphere and/or binding of the radical molecule to the sphere matrix. Future directions for progress are also discussed.

  7. Pulse FT NMR of non-equilibrium states of half-integer spin quadrupolar nuclei in single crystals.

    PubMed

    Nakashima, Thomas T; Harris, Kristopher J; Wasylishen, Roderick E

    2010-02-01

    For quadrupolar nuclei with spin quantum numbers equal to 3/2, 5/2 and 7/2, the intensities of the NMR transitions in a single crystal are examined as a function of the rf excitation flip angle. Single-quantum NMR intensities are calculated using density matrix theory beginning under various non-equilibrium conditions and are compared with those determined experimentally. As a representative spin-3/2 system, the flip-angle dependence of the (23)Na NMR intensities of a single crystal of NaNO(3) was investigated beginning with the inversion of the populations associated with one of the satellite transitions. Subsequently, the populations of both satellite transitions were inverted using highly frequency-selective hyperbolic secant pulses. Calculated and experimental intensities are in good agreement. As an example of a spin-5/2 system, the flip-angle dependence of the (27)Al NMR transition intensities was determined using a single crystal of sapphire, Al(2)O(3), starting under different nuclear spin population conditions. The experimental trends mimicked those predicted by the density matrix calculations but the agreement was not as good as for the spin-3/2 case. Some SIMPSON simulations were also carried out to confirm the results generated by our density matrix calculations. The theoretical flip-angle behavior of the NMR transition intensities obtained from a spin-7/2 spin system is also discussed.

  8. Probing the effective nuclear-spin magnetic field in a single quantum dot via full counting statistics

    SciTech Connect

    Xue, Hai-Bin; Nie, Yi-Hang; Chen, Jingzhe; Ren, Wei

    2015-03-15

    We study theoretically the full counting statistics of electron transport through a quantum dot weakly coupled to two ferromagnetic leads, in which an effective nuclear-spin magnetic field originating from the configuration of nuclear spins is considered. We demonstrate that the quantum coherence between the two singly-occupied eigenstates and the spin polarization of two ferromagnetic leads play an important role in the formation of super-Poissonian noise. In particular, the orientation and magnitude of the effective field have a significant influence on the variations of the values of high-order cumulants, and the variations of the skewness and kurtosis values are more sensitive to the orientation and magnitude of the effective field than the shot noise. Thus, the high-order cumulants of transport current can be used to qualitatively extract information on the orientation and magnitude of the effective nuclear-spin magnetic field in a single quantum dot. - Highlights: • The effective nuclear-spin magnetic field gives rise to the off-diagonal elements of the reduced density matrix of single QD. • The off-diagonal elements of reduced density matrix of the QD have a significant impact on the high-order current cumulants. • The high-order current cumulants are sensitive to the orientation and magnitude of the effective nuclear-spin magnetic field. • The FCS can be used to detect the orientation and magnitude of the effective nuclear-spin magnetic field in a single QD.

  9. Implementation of Dynamically Corrected Gates on a Single Electron Spin in Diamond

    NASA Astrophysics Data System (ADS)

    Rong, Xing; Geng, Jianpei; Wang, Zixiang; Zhang, Qi; Ju, Chenyong; Shi, Fazhan; Duan, Chang-Kui; Du, Jiangfeng

    2014-02-01

    Precise control of an open quantum system is critical to quantum information processing but is challenging due to inevitable interactions between the quantum system and the environment. We demonstrated experimentally a type of dynamically corrected gates using only bounded-strength pulses on the nitrogen-vacancy centers in diamond. The infidelity of quantum gates caused by a nuclear-spin bath is reduced from being the second order to the sixth order of the noise-to-control-field ratio, which offers greater efficiency in reducing infidelity. The quantum gates have been protected to the limit essentially set by the spin-lattice relaxation time T1. Our work marks an important step towards fault-tolerant quantum computation in realistic systems.

  10. Fast deterministic switching in orthogonal spin torque devices via the control of the relative spin polarizations

    NASA Astrophysics Data System (ADS)

    Park, Junbo; Ralph, D. C.; Buhrman, R. A.

    2013-12-01

    We model 100 ps pulse switching dynamics of orthogonal spin transfer (OST) devices that employ an out-of-plane polarizer and an in-plane polarizer. Simulation results indicate that increasing the spin polarization ratio, CP = PIPP/POPP, results in deterministic switching of the free layer without over-rotation (360° rotation). By using spin torque asymmetry to realize an enhanced effective PIPP, we experimentally demonstrate this behavior in OST devices in parallel to anti-parallel switching. Modeling predicts that decreasing the effective demagnetization field can substantially reduce the minimum CP required to attain deterministic switching, while retaining low critical switching current, Ip ˜ 500 μA.

  11. Controllable photo-induced spin and valley filtering in silicene

    NASA Astrophysics Data System (ADS)

    Mohammadi, Yawar; Nia, Borhan Arghavani

    2016-08-01

    We investigate theoretically the spin- and valley-dependent ballistic transport in silicene, which is assumed to be modulated by local application of a gate voltage and off-resonant circularly polarized light. We show that, due to the coupling between valley and spin degrees of freedom in silicene, the current through it is spin and valley polarized. The spin (valley) polarization can be enhanced by tuning the light intensity and the value of the perpendicular electric field, leading to perfect spin (valley) filtering for certain of their values. It is also found that the spin (valley) polarization can be inverted by reversing the perpendicular electric field (by reversing the perpendicular electric field or reversing the circular polarization of the light irradiation).

  12. Single-edge transport in an InAs/GaSb quantum spin Hall insulator

    NASA Astrophysics Data System (ADS)

    Couëdo, François; Irie, Hiroshi; Suzuki, Kyoichi; Onomitsu, Koji; Muraki, Koji

    2016-07-01

    We report transport measurements in a single edge channel of an InAs/GaSb quantum spin Hall insulator, where the conduction occurs through only one pair of counterpropagating edge modes. By using a specific sample design involving highly asymmetric current paths, we electrically isolate a single edge channel of the two-dimensional topological insulator from the other edge. This enables us to probe a single edge by multiterminal measurements. Both two-terminal and four-terminal resistances show a nearly quantized plateau around h /e2 for a 4-μ m -long edge, indicating quasiballistic transport. Our approach is advantageous in that it allows us to gain insight into a microscopic region from local measurements.

  13. Digital atom interferometer with single particle control on a discretized space-time geometry

    PubMed Central

    Steffen, Andreas; Alberti, Andrea; Alt, Wolfgang; Belmechri, Noomen; Hild, Sebastian; Karski, Michał; Widera, Artur; Meschede, Dieter

    2012-01-01

    Engineering quantum particle systems, such as quantum simulators and quantum cellular automata, relies on full coherent control of quantum paths at the single particle level. Here we present an atom interferometer operating with single trapped atoms, where single particle wave packets are controlled through spin-dependent potentials. The interferometer is constructed from a sequence of discrete operations based on a set of elementary building blocks, which permit composing arbitrary interferometer geometries in a digital manner. We use this modularity to devise a space-time analogue of the well-known spin echo technique, yielding insight into decoherence mechanisms. We also demonstrate mesoscopic delocalization of single atoms with a separation-to-localization ratio exceeding 500; this result suggests their utilization beyond quantum logic applications as nano-resolution quantum probes in precision measurements, being able to measure potential gradients with precision 5 × 10-4 in units of gravitational acceleration g. PMID:22665771

  14. Quantum control of electron spins in the two-dimensional electron gas of a CdTe quantum well with a pair of Raman-resonant phase-locked laser pulses

    NASA Astrophysics Data System (ADS)

    Sweeney, Timothy M.; Phelps, Carey; Wang, Hailin

    2011-08-01

    We demonstrated optical spin control of a two-dimensional electron gas in a modulation-doped CdTe quantum well by driving a spin-flip Raman transition with a pair of phase-locked laser pulses. In contrast to single-pulse optical spin control, which features a fixed spin-rotation axis, manipulation of the initial relative phase of the pulse pair enables us to control the axis of the optical spin rotation. We show that the Raman pulse pair acts like an effective microwave field, mapping the relative optical phase onto the phase of the electron spin polarization and making possible ultrafast, all-optical, and full quantum control of the electron spins.

  15. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP ENTITLED ''SINGLE SPIN ASYMMETRIES'' (VOLUME 75)

    SciTech Connect

    YUAN, F.; VOGELSANG, W.

    2005-06-01

    Single-transverse spin asymmetries (SSA) in strong interactions have a long history, starting from the 1970s and 1980s when surprisingly large single-transverse spin asymmetries were observed in p+p {yields} {pi}X and pp {yields} {Lambda} + X, where really none were expected. They have again attracted much interest in recent years from both experimental and theoretical sides. In particular, first measurements by the STAR, PHENIX, and BRAHMS collaborations at RHIC have now become available which again reveal large single transverse spin asymmetries for hadron production in polarized proton proton scattering. This extends the SSA observations from the fixed target energy range to the collider regime. Meanwhile, experimental studies in Deep Inelastic Scattering by the HERMES collaboration at DESY, SMC at CERN, and CLAS at JLab also show a remarkably large SSA in semi-inclusive hadron production, {gamma}*p {yields} {pi}X, when the proton is transversely polarized. On the theoretical side, there are several approaches to understanding SSA within Quantum Chromodynamics (QCD). For example, to explain the large SSAs for hadron production in hadron collisions, a mechanism that takes into account the contribution from quark-gluon-quark correlations (twist-3) in the nucleon was proposed. On the other hand, possible origins of SSA in DIS and hadronic scattering were also found in leading-twist transverse momentum dependent parton distributions. Current theoretical efforts aim at a better conceptual understanding of these two types of mechanisms, and of their connections. We were very happy at this timely date to bring together the theorists and experimentalists of this field to review and discuss the current theoretical status and the latest experimental results. The whole workshop contained 25 formal talks, both experiment (15) and theory (10), and a few informal talks and many fruitful discussions. The topics covered all the relevant SSA observables, including in Deep

  16. Spin projection of single-determinant wavefunctions. [application to hydrocarbon radicals and ions

    NASA Technical Reports Server (NTRS)

    Phillips, D. H.; Schug, J. C.

    1974-01-01

    The components of the one- and two-particle density matrices resulting from spin projection of a single-determinant wave function are rederived by the method of expansion in terms of the natural orbitals of charge density, and the results are found to diverge from those given by Harriman and Sando for the two-particle case. The theory is generalized to include molecules with unequal numbers of electrons and basis orbitals and is applied to a number of organic molecules and ions. The correctness and internal consistency of the results argue in favor of the modification described.

  17. Cytoplasmic Solvent Structure of Single Barnacle Muscle Cells Studied by Electron Spin Resonance

    PubMed Central

    Sachs, Fred; Latorre, Ramon

    1974-01-01

    A free radical probe was introduced into single barnacle muscle cells, and its freedom of motion inferred from the spin resonance spectra. The probe reported an average local viscosity of 5-10 cp compared with 1 cp for pure water. From a comparison of the temperature dependence of the probe's tumbling rate in model aqueous systems and in the muscle we concluded that in the muscle the probe was undergoing fast exchange between sites of different mobility. Thus 10 cp must be taken as an upper limit for the viscosity of most cell water. PMID:4364470

  18. Trigluon correlations and single transverse spin asymmetry in open charm production

    SciTech Connect

    Kang Zhongbo; Qiu Jianwei

    2009-08-04

    We study the single transverse-spin asymmetry for open charm production in the semiinclusive lepton-hadron deep inelastic scattering (SIDIS) and pp collision. Within collinear factorization approach, we find that the asymmetry is sensitive to the twist-3 trigluon correlation functions in the proton. With a simple model for the trigluon correlation functions, we estimate the asymmetry in SIDIS for both COMPASS and eRHIC kinematics, as well as in pp collision at RHIC energy. We discuss the possibilities of extracting the trigluon correlation functions in these experiments.

  19. Generating Entangled Spin States for Quantum Metrology by Single-Photon Detection

    NASA Astrophysics Data System (ADS)

    McConnell, Robert; Zhang, Hao; Cuk, Senka; Hu, Jiazhong; Schleier-Smith, Monika; Vuletic, Vladan

    2014-05-01

    We present a proposal and latest experimental results on a probabilistic but heralded scheme to generate non-Gaussian entangled states of collective spin in large atomic ensembles by means of single-photon detection. One photon announces the preparation of a Dicke state, while two or more photons announce Schrödinger cat states. The entangled states thus produced allow interferometry below the Standard Quantum Limit (SQL). The method produces nearly pure states even for finite photon detection efficiency and weak atom-photon coupling. The entanglement generation can be made quasi-deterministic by means of repeated trial and feedback.

  20. Probing the spin state of a single electron trap by random telegraph signal.

    PubMed

    Xiao, M; Martin, I; Jiang, H W

    2003-08-15

    We have studied the random telegraph signal (RTS) generated by a single paramagnetic spin center adjacent to a submicrometer silicon metal-oxide-semiconductor field-effect transistor. An in-plane magnetic field induces a substantial change in the statistics of the RTS. We show that a model using the grand partition theorem can qualitatively explain the change in statistics of the RTS as a function of the applied magnetic field. While the data at high temperatures can be well described by this simple model, quantitative discrepancy increases as the temperature is lowered. PMID:12935055

  1. Nanoscale magnetic field mapping with a single spin scanning probe magnetometer

    SciTech Connect

    Rondin, L.; Tetienne, J.-P.; Spinicelli, P.; Roch, J.-F.; Jacques, V.; Dal Savio, C.; Karrai, K.; Dantelle, G.; Thiaville, A.; Rohart, S.

    2012-04-09

    We demonstrate quantitative magnetic field mapping with nanoscale resolution, by applying a lock-in technique on the electron spin resonance frequency of a single nitrogen-vacancy defect placed at the apex of an atomic force microscope tip. In addition, we report an all-optical magnetic imaging technique which is sensitive to large off-axis magnetic fields, thus extending the operation range of diamond-based magnetometry. Both techniques are illustrated by using a magnetic hard disk as a test sample. Owing to the non-perturbing and quantitative nature of the magnetic probe, this work should open up numerous perspectives in nanomagnetism and spintronics.

  2. Single crystal growth in spin-coated films of polymorphic phthalocyanine derivative under solvent vapor

    SciTech Connect

    Higashi, T.; Ohmori, M.; Ramananarivo, M. F.; Fujii, A. Ozaki, M.

    2015-12-01

    The effects of solvent vapor on spin-coated films of a polymorphic phthalocyanine derivative were investigated. Growth of single crystal films via redissolving organic films under solvent vapor was revealed by in situ microscopic observations of the films. X-ray diffraction measurement of the films after exposing to solvent vapor revealed the phase transition of polymorphs under solvent vapor. The direction of crystal growth was clarified by measuring the crystal orientation in a grown monodomain film. The mechanism of crystal growth based on redissolving organic films under solvent vapor was discussed in terms of the different solubilities of the polymorphs.

  3. Flight investigation of the effects of an outboard wing-leading-edge modification on stall/spin characteristics of a low-wing, single-engine, T-tail light airplane

    NASA Technical Reports Server (NTRS)

    Stough, H. Paul, III; Dicarlo, Daniel J.; Patton, James M., Jr.

    1987-01-01

    Flight tests were performed to investigate the change in stall/spin characteristics due to the addition of an outboard wing-leading-edge modification to a four-place, low-wing, single-engine, T-tail, general aviation research airplane. Stalls and attempted spins were performed for various weights, center of gravity positions, power settings, flap deflections, and landing-gear positions. Both stall behavior and wind resistance were improved compared with the baseline airplane. The latter would readily spin for all combinations of power settings, flap deflections, and aileron inputs, but the modified airplane did not spin at idle power or with flaps extended. With maximum power and flaps retracted, the modified airplane did enter spins with abused loadings or for certain combinations of maneuver and control input. The modified airplane tended to spin at a higher angle of attack than the baseline airplane.

  4. Continuous dynamical decoupling of a single diamond nitrogen-vacancy center spin with a mechanical resonator

    NASA Astrophysics Data System (ADS)

    MacQuarrie, E. R.; Gosavi, T. A.; Bhave, S. A.; Fuchs, G. D.

    2015-12-01

    Inhomogeneous dephasing from uncontrolled environmental noise can limit the coherence of a quantum sensor or qubit. For solid-state spin qubits such as the nitrogen-vacancy (NV) center in diamond, a dominant source of environmental noise is magnetic field fluctuations due to nearby paramagnetic impurities and instabilities in a magnetic bias field. In this work, we use ac stress generated by a diamond mechanical resonator to engineer a dressed spin basis in which a single NV center qubit is less sensitive to its magnetic environment. For a qubit in the thermally isolated subspace of this protected basis, we prolong the dephasing time T2* from 2.7 ±0.1 to 15 ±1 μ s by dressing with a Ω /2 π =581 ±2 kHz mechanical Rabi field. Furthermore, we develop a model that quantitatively predicts the relationship between Ω and T2* in the dressed basis. Our model suggests that a combination of magnetic field fluctuations and hyperfine coupling to nearby nuclear spins limits the protected coherence time over the range of Ω accessed here. We show that amplitude noise in Ω will dominate the dephasing for larger driving fields.

  5. Molecular quantum spintronics: supramolecular spin valves based on single-molecule magnets and carbon nanotubes.

    PubMed

    Urdampilleta, Matias; Nguyen, Ngoc-Viet; Cleuziou, Jean-Pierre; Klyatskaya, Svetlana; Ruben, Mario; Wernsdorfer, Wolfgang

    2011-01-01

    We built new hybrid devices consisting of chemical vapor deposition (CVD) grown carbon nanotube (CNT) transistors, decorated with TbPc(2) (Pc = phthalocyanine) rare-earth based single-molecule magnets (SMMs). The drafting was achieved by tailoring supramolecular π-π interactions between CNTs and SMMs. The magnetoresistance hysteresis loop measurements revealed steep steps, which we can relate to the magnetization reversal of individual SMMs. Indeed, we established that the electronic transport properties of these devices depend strongly on the relative magnetization orientations of the grafted SMMs. The SMMs are playing the role of localized spin polarizer and analyzer on the CNT electronic conducting channel. As a result, we measured magneto-resistance ratios up to several hundred percent. We used this spin valve effect to confirm the strong uniaxial anisotropy and the superparamagnetic blocking temperature (T(B) ~ 1 K) of isolated TbPc(2) SMMs. For the first time, the strength of exchange interaction between the different SMMs of the molecular spin valve geometry could be determined. Our results introduce a new design for operable molecular spintronic devices using the quantum effects of individual SMMs.

  6. Excitation and detection of propagating spin waves at the single magnon level.

    NASA Astrophysics Data System (ADS)

    Karenowska, Alexy; Patterson, Andrew; Peterer, Michael; Magnússon, Einar; Leek, Peter

    2015-03-01

    The fields of spin-wave dynamics and magnonics have made substantial contributions to our understanding of fundamental magnetism, and are increasingly widely acknowledged to be areas of solid-state physics with significant technological potential. To date however, experimental activity has focused on the study and possible application of room-temperature systems operating within classical limits. Here, we report a series of experiments in which we demonstrate, for the first time, the excitation and detection of propagating spin waves at the single magnon level. Our results, which have been obtained at cryogenic temperatures using an yttrium iron garnet spin-wave waveguide, serve as evidence that the experimental tools now exist to permit us to create microwave (i.e. GHz frequency) quantum circuits incorporating dispersive magnon systems. This allows us to anticipate the possibility both of exploring quantum aspects of magnon physics with new experimental clarity, and of examining how this physics -- in particular, the magnon's highly tunable dispersion, its readily accessible nonlinearity, and its capacity to couple to optical excitations and electron-based spintronic systems -- might have a role to play in new microwave quantum technologies.

  7. Molecular quantum spintronics: supramolecular spin valves based on single-molecule magnets and carbon nanotubes.

    PubMed

    Urdampilleta, Matias; Nguyen, Ngoc-Viet; Cleuziou, Jean-Pierre; Klyatskaya, Svetlana; Ruben, Mario; Wernsdorfer, Wolfgang

    2011-01-01

    We built new hybrid devices consisting of chemical vapor deposition (CVD) grown carbon nanotube (CNT) transistors, decorated with TbPc(2) (Pc = phthalocyanine) rare-earth based single-molecule magnets (SMMs). The drafting was achieved by tailoring supramolecular π-π interactions between CNTs and SMMs. The magnetoresistance hysteresis loop measurements revealed steep steps, which we can relate to the magnetization reversal of individual SMMs. Indeed, we established that the electronic transport properties of these devices depend strongly on the relative magnetization orientations of the grafted SMMs. The SMMs are playing the role of localized spin polarizer and analyzer on the CNT electronic conducting channel. As a result, we measured magneto-resistance ratios up to several hundred percent. We used this spin valve effect to confirm the strong uniaxial anisotropy and the superparamagnetic blocking temperature (T(B) ~ 1 K) of isolated TbPc(2) SMMs. For the first time, the strength of exchange interaction between the different SMMs of the molecular spin valve geometry could be determined. Our results introduce a new design for operable molecular spintronic devices using the quantum effects of individual SMMs. PMID:22072910

  8. Controlling the flow of spin and charge in nanoscopic topological insulators

    NASA Astrophysics Data System (ADS)

    Van Dyke, John S.; Morr, Dirk K.

    2016-02-01

    Controlling the flow of spin and charge currents in topological insulators (TIs) is a crucial requirement for applications in quantum computation and spin electronics. We demonstrate that such control can be established in nanoscopic two-dimensional TIs by breaking their time-reversal symmetry via magnetic defects. This allows for the creation of nearly fully spin-polarized charge currents, and the design of highly tunable spin diodes. Similar effects can also be realized in mesoscale hybrid structures in which TIs interface with ferro- or antiferromagnets.

  9. Harnessing spin precession with dissipation

    PubMed Central

    Crisan, A. D.; Datta, S.; Viennot, J. J.; Delbecq, M. R.; Cottet, A.; Kontos, T.

    2016-01-01

    Non-collinear spin transport is at the heart of spin or magnetization control in spintronics devices. The use of nanoscale conductors exhibiting quantum effects in transport could provide new paths for that purpose. Here we study non-collinear spin transport in a quantum dot. We use a device made out of a single-wall carbon nanotube connected to orthogonal ferromagnetic electrodes. In the spin transport signals, we observe signatures of out of equilibrium spin precession that are electrically tunable through dissipation. This could provide a new path to harness spin precession in nanoscale conductors. PMID:26816050

  10. Harnessing spin precession with dissipation

    NASA Astrophysics Data System (ADS)

    Crisan, A. D.; Datta, S.; Viennot, J. J.; Delbecq, M. R.; Cottet, A.; Kontos, T.

    2016-01-01

    Non-collinear spin transport is at the heart of spin or magnetization control in spintronics devices. The use of nanoscale conductors exhibiting quantum effects in transport could provide new paths for that purpose. Here we study non-collinear spin transport in a quantum dot. We use a device made out of a single-wall carbon nanotube connected to orthogonal ferromagnetic electrodes. In the spin transport signals, we observe signatures of out of equilibrium spin precession that are electrically tunable through dissipation. This could provide a new path to harness spin precession in nanoscale conductors.

  11. Density-Functional and Coupled-Cluster Singles-and-Doubles Calculations of the Nuclear Shielding and Indirect Nuclear Spin-Spin Coupling Constants of o-Benzyne.

    PubMed

    Helgaker, Trygve; Jaszuński, Michał

    2007-01-01

    Density-functional theory (DFT) and coupled-cluster singles-and-doubles (CCSD) theory are applied to compute the nuclear magnetic resonance (NMR) shielding and indirect nuclear spin-spin coupling constants of o-benzyne, whose biradical nature makes it difficult to study both experimentally and theoretically. Because of near-equilibrium triplet instabilities that follow from its biradical character, the calculated DFT NMR properties of o-benzyne are unusually sensitive to details of the exchange-correlation functional. However, this sensitivity is greatly reduced if these properties are calculated at the equilibrium of the chosen functional. A strong correlation is demonstrated between the quality of the calculated indirect spin-spin coupling constants and the quality of the calculated lowest triplet excitation energy in o-benzyne. Orbital-unrelaxed coupled-cluster theory should be less affected by such instabilities, and the CCSD NMR properties were only calculated at the experimental equilibrium geometry. For the shielding constants, the results in best agreement with experimental results are obtained with CCSD theory and with the Keal-Tozer KT1 and KT2 functionals. For the triply bonded carbon atoms, these models yield an isotropic shielding of 1.3, -3.3, and -1.2 ppm, respectively, compared with the experimentally observed shielding of 3.7 ppm for incarcerated o-benzyne. For the indirect spin-spin coupling constants, the CCSD model and the Perdew-Burke-Ernzerhof functional both yield reliable results; for the most interesting spin-spin coupling constant, (1)J (C⋮C), we obtain 210 and 209 Hz with these two models, respectively, somewhat above the recently reported experimental value of 177.9 ± 0.7 Hz for o-benzyne inside a molecular container, suggesting large incarceration effects.

  12. Electrically controllable sudden reversals in spin and valley polarization in silicene.

    PubMed

    Zhang, Qingtian; Chan, K S; Li, Jingbo

    2016-01-01

    We study the spin and valley dependent transport in a silicene superlattice under the influence of a magnetic exchange field, a perpendicular electric field and a voltage potential. It is found that a gate-voltage-controllable fully spin and valley polarized current can be obtained in the proposed device, and the spin and valley polarizations are sensitive oscillatory functions of the voltage potential. In properly designed superlattice structure, the spin and valley polarizations can be reversed from -100% to 100% by a slight change in the external voltage potential. The energy dispersion relations of the superlattice structure are also investigated, which helps us to understand the effects of the superlattice structure. The switching of the spin direction and the valley of the tunneling electrons by a gate voltage enables new possibilities for spin or valley control in silicene-based spintronics and valleytronics. PMID:27647320

  13. Electrically controllable sudden reversals in spin and valley polarization in silicene

    PubMed Central

    Zhang, Qingtian; Chan, K. S.; Li, Jingbo

    2016-01-01

    We study the spin and valley dependent transport in a silicene superlattice under the influence of a magnetic exchange field, a perpendicular electric field and a voltage potential. It is found that a gate-voltage-controllable fully spin and valley polarized current can be obtained in the proposed device, and the spin and valley polarizations are sensitive oscillatory functions of the voltage potential. In properly designed superlattice structure, the spin and valley polarizations can be reversed from −100% to 100% by a slight change in the external voltage potential. The energy dispersion relations of the superlattice structure are also investigated, which helps us to understand the effects of the superlattice structure. The switching of the spin direction and the valley of the tunneling electrons by a gate voltage enables new possibilities for spin or valley control in silicene-based spintronics and valleytronics. PMID:27647320

  14. Electrically controllable sudden reversals in spin and valley polarization in silicene

    NASA Astrophysics Data System (ADS)

    Zhang, Qingtian; Chan, K. S.; Li, Jingbo

    2016-09-01

    We study the spin and valley dependent transport in a silicene superlattice under the influence of a magnetic exchange field, a perpendicular electric field and a voltage potential. It is found that a gate-voltage-controllable fully spin and valley polarized current can be obtained in the proposed device, and the spin and valley polarizations are sensitive oscillatory functions of the voltage potential. In properly designed superlattice structure, the spin and valley polarizations can be reversed from ‑100% to 100% by a slight change in the external voltage potential. The energy dispersion relations of the superlattice structure are also investigated, which helps us to understand the effects of the superlattice structure. The switching of the spin direction and the valley of the tunneling electrons by a gate voltage enables new possibilities for spin or valley control in silicene-based spintronics and valleytronics.

  15. CdSe/ZnSe quantum dot with a single Mn{sup 2+} ion—A new system for a single spin manipulation

    SciTech Connect

    Smoleński, T.

    2015-03-21

    We present a magneto-optical study of individual self-assembled CdSe/ZnSe quantum dots doped with single Mn{sup 2+} ions. Properties of the studied dots are analyzed analogously to more explored system of Mn-doped CdTe/ZnTe dots. Characteristic sixfold splitting of the neutral exciton emission line as well as its evolution in the magnetic field are described using a spin Hamiltonian model. Dynamics of both exciton recombination and Mn{sup 2+} spin relaxation are extracted from a series of time-resolved experiments. Presence of a single dopant is shown not to affect the average excitonic lifetime measured for a number of nonmagnetic and Mn-doped dots. On the other hand, non-resonant pumping is demonstrated to depolarize the Mn{sup 2+} spin in a quantum dot placed in external magnetic field. This effect is utilized to determine the ion spin relaxation time in the dark.

  16. Full Controllability of a Singlet-Triplet Qubit Coupled to a Nuclear Spin Qubit

    NASA Astrophysics Data System (ADS)

    Baczewski, Andrew D.; Gamble, John King; Jacobson, N. Tobias; Muller, Richard P.; Nielsen, Erik; Carr, Stephen M.; Carroll, Malcolm S.; Curry, Matthew; Harvey-Collard, Patrick; Jock, Ryan M.; Rudolph, Martin

    Recent experimental developments indicate that it is possible to drive coherent singlet-triplet rotations in a MOS quantum dot coupled to a single nearby phosphorus donor through the electron-nucleus hyperfine interaction. With the addition of NMR, we propose that it is possible to achieve universal 2-qubit control spanning i.) an electronic singlet-triplet subspace of the dot, ii.) the spin-1/2 donor nucleus, and iii.) entangling operations between them. We will assess the practicality of such an approach given realistic experimental conditions and constraints, including a comparison of pulsed and RF control of the detuning between the donor and dot. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Security Administration under Contract DE-AC04-94AL85000.

  17. Spin-glass behaviors in carrier polarity controlled Fe3-xTixO4 semiconductor thin films

    NASA Astrophysics Data System (ADS)

    Yamahara, H.; Seki, M.; Adachi, M.; Takahashi, M.; Nasu, H.; Horiba, K.; Kumigashira, H.; Tabata, H.

    2015-08-01

    Carrier-type control of spin-glass (cluster spin-glass) is studied in order to engineer basic magnetic semiconductor elements using the memory functions of spin-glass. A key of carrier-polarity control in magnetite is the valence engineering between Fe(II) and Fe(III) that is achieved by Ti(IV) substitution. Single phases of (001)-oriented Fe3-xTixO4 thin films have been obtained on spinel MgAl2O4 substrates by pulsed laser deposition. Thermoelectric power measurements reveal that Ti-rich films (x = 0.8) show p-type conduction, while Ti-poor films (x = 0.6-0.75) show n-type conduction. The systematic Fe(III) reduction to Fe(II) followed by Ti(IV) substitution in the octahedral sublattice is confirmed by the X-ray absorption spectra. All of the Fe3-xTixO4 films (x = 0.6-0.8) exhibit ferrimagnetism above room temperature. Next, the spin-glass behaviors of Ti-rich Fe2.2Ti0.8O4 film are studied, since this magnetically diluted system is expected to exhibit the spin-glass behaviors. The DC magnetization and AC susceptibility measurements for the Ti-rich Fe2.2Ti0.8O4 film reveal the presence of the spin glass phase. Thermal- and magnetic-field-history memory effects are observed and are attributed to the long time-decay nature of remanent magnetization. The detailed analysis of the time-dependent thermoremanent magnetization reveals the presence of the cluster spin glass state.

  18. Indirect exchange interaction in fully metal-semiconductor separated single-walled carbon nanotubes revealed by electron spin resonance

    NASA Astrophysics Data System (ADS)

    Havlicek, M.; Jantsch, W.; Wilamowski, Z.; Yanagi, K.; Kataura, H.; Rümmeli, M. H.; Malissa, H.; Tyryshkin, A.; Lyon, S.; Chernov, A.; Kuzmany, H.

    2012-07-01

    The ESR response from highly metal-semiconductor (M-SC) separated single-walled carbon nanotubes (SWCNTs) for temperatures T between 0.39 and 200 K is characteristically different for the two systems. The signal originates from defect spins but interaction with free electrons leads to a larger linewidth for M tubes. The latter decreases with increasing T, whereas it increases with T for SC tubes. The spins undergo a ferromagnetic phase transition below around 10 K. Indirect exchange is suggested to be responsible for the spin-spin interaction, supported by RKKY interaction in the case of M tubes. For SC tubes, the spin-lattice relaxation via an Orbach process is suggested to determine the linewidth.

  19. Wafer-Scale Precise Patterning of Organic Single-Crystal Nanowire Arrays via a Photolithography-Assisted Spin-Coating Method.

    PubMed

    Deng, Wei; Zhang, Xiujuan; Wang, Liang; Wang, Jincheng; Shang, Qixun; Zhang, Xiaohong; Huang, Liming; Jie, Jiansheng

    2015-12-01

    A photolithography-assisted spin-coating approach is developed to produce single-crystal organic nanowire (NW) arrays at designated locations with high precision and high efficiency. This strategy enables the large-scale fabrication of organic NW arrays with nearly the same accuracy, reliability, and flexibility as photolithography. The high mobilities of the organic NWs enable the control of the switch of multicolored light-emitting devices with good stability.

  20. Quadratic coupling between a classical nanomechanical oscillator and a single spin

    NASA Astrophysics Data System (ADS)

    Dhingra, Shonali

    Though the motions of macroscopic objects must ultimately be governed by quantum mechanics, the distinctive features of quantum mechanics can be hidden or washed out by thermal excitations and coupling to the environment. For the work of this thesis, we tried to develop a hybrid system consisting a classical and a quantum component, which can be used to probe the quantum nature of both these components. This hybrid system quadratically coupled a nanomechanical oscillator (NMO) with a single spin in presence of a uniform external magnetic field. The NMO was fabricated out of single-layer graphene, grown using Chemical Vapor Deposition (CVD) and patterned using various lithography and etching techniques. The NMO was driven electrically and detected optically. The NMO's resonant frequencies, and their stabilities were studied. The spin originated from a nitrogen vacancy (NV) center in a diamond nanocrystal which is positioned on the NMO. In presence of an external magnetic field, we show that the NV centers are excellen theta2 sensors. Their sensitivity is shown to increase much faster than linearly with the external magnetic field and diverges as the external field approaches an internally-defined limit. Both these components of the hybrid system get coupled by physical placement of NVcontaining diamond nanocrystals on top of NMO undergoing torsional mode of oscillation, in presence of an external magnetic field. The capability of the NV centers to detect the quadratic behavior of the oscillation angle of the NMO with excellent sensitivity, ensures quantum non-demolition (QND) measurement of both components of the hybrid system. This enables a bridge between the quantum and classical worlds for a simple readout of the NV center spin and observation of the discrete states of the NMO. This system could become the building block for a wide range of quantum nanomechanical devices.

  1. Spin-glass transition in Ni carbide single crystal nanoparticles with Ni3C - type structure

    NASA Astrophysics Data System (ADS)

    Fujieda, S.; Kuboniwa, T.; Shinoda, K.; Suzuki, S.; Echigoya, J.

    2016-05-01

    Hexagonal shaped nanoparticles about 60 nm in size were successfully synthesized in tetraethylene glycol solution containing polyvinylpyrrolidone. By the analysis of the electron diffraction pattern, these were identified as a single crystal of Ni carbide with Ni3C - type structure. Their magnetization curve at 5 K was not completely saturated under a magnetic field of 5 T. The thermomagnetization curves after zero-field cooling and after field cooling exhibited the magnetic cooling effect at low temperatures. Furthermore, the 2nd order nonlinear term of AC magnetic susceptibility exhibited a negative divergence at about 17 K. It is concluded that Ni carbide single crystal nanoparticles with the Ni3C - type structure exhibit spin-glass transition at low temperatures.

  2. Cluster VS. Single-Spin ALGORITHMS—WHICH are More Efficient?

    NASA Astrophysics Data System (ADS)

    Ito, N.; Kohring, G. A.

    A comparison between single-cluster and single-spin algorithms is made for the Ising model in 2 and 3 dimensions. We compare the amount of computer time needed to achieve a given level of statistical accuracy, rather than the speed in terms of site updates per second or the dynamical critical exponents. Our main result is that the cluster algorithms become more efficient when the system size, Ld, exceeds, L~70-300 for d=2 and l~80-200 for d=3. The exact value of the crossover is dependent upon the computer being used. The lower end of the crossover range is typical of workstations while the higher end is typical of vector computers. Hence, even for workstations, the system sizes needed for efficient use of the cluster algorithm is relatively large.

  3. Symmetry-lowering lattice distortion at the spin reorientation in MnBi single crystals

    DOE PAGES

    McGuire, Michael A.; Cao, Huibo; Chakoumakos, Bryan C.; Sales, Brian C.

    2014-11-18

    Here we report structural and physical properties determined by measurements on large single crystals of the anisotropic ferromagnet MnBi. The findings support the importance of magnetoelastic effects in this material. X-ray diffraction reveals a structural phase transition at the spin reorientation temperature TSR = 90 K. The distortion is driven by magneto-elastic coupling, and upon cooling transforms the structure from hexagonal to orthorhombic. Heat capacity measurements show a thermal anomaly at the crystallographic transition, which is suppressed rapidly by applied magnetic fields. Effects on the transport and anisotropic magnetic properties of the single crystals are also presented. Increasing anisotropy ofmore » the atomic displacement parameters for Bi with increasing temperature above TSR is revealed by neutron diffraction measurements. It is likely that this is directly related to the anisotropic thermal expansion in MnBi, which plays a key role in the spin reorientation and magnetocrystalline anisotropy. Finally, the identification of the true ground state crystal structure reported here may be important for future experimental and theoretical studies of this permanent magnet material, which have to date been performed and interpreted using only the high temperature structure.« less

  4. Efficient route to high-bandwidth nanoscale magnetometry using single spins in diamond

    PubMed Central

    Puentes, Graciana; Waldherr, Gerald; Neumann, Philipp; Balasubramanian, Gopalakrishnan; Wrachtrup, Jörg

    2014-01-01

    Nitrogen-vacancy (NV) center in diamond is a promising quantum metrology tool finding applications across disciplines. The spin sensor measures magnetic fields, electric fields and temperature with nano-scale precision and is fully operable under ambient conditions. Moreover, it achieves precision scaling inversely with total measurement time σB ∝ 1/T (Heisenberg scaling) rather than as the inverse of the square root of T, with the Shot-Noise limit. This scaling can be achieved by means of phase estimation algorithms (PEAs), in combination with single-shot read-out. Despite their accuracy, the range of applicability of PEAs is limited to sensing single frequencies with negligible temporal fluctuations. Nuclear Magnetic Resonance (NMR) signals from molecules often contain multifrequency components and sensing them using PEA is ruled out. Here we propose an alternative method for precision magnetometry in frequency multiplexed signals via compressive sensing (CS) techniques focusing on nanoscale NMR. We show that CS can provide for precision scaling approximately as σB ≈ 1/T, as well as for a 5-fold increase in sensitivity over dynamic-range gain, in addition to reducing the total number of resources required. We illustrate our method by taking model solid-state spectra of Glycine acquired under Magic Angle Spinning conditions. PMID:24728454

  5. Efficient route to high-bandwidth nanoscale magnetometry using single spins in diamond.

    PubMed

    Puentes, Graciana; Waldherr, Gerald; Neumann, Philipp; Balasubramanian, Gopalakrishnan; Wrachtrup, Jörg

    2014-04-14

    Nitrogen-vacancy (NV) center in diamond is a promising quantum metrology tool finding applications across disciplines. The spin sensor measures magnetic fields, electric fields and temperature with nano-scale precision and is fully operable under ambient conditions. Moreover, it achieves precision scaling inversely with total measurement time σB ∝ 1/T (Heisenberg scaling) rather than as the inverse of the square root of T, with σB = √T the Shot-Noise limit. This scaling can be achieved by means of phase estimation algorithms (PEAs), in combination with single-shot read-out. Despite their accuracy, the range of applicability of PEAs is limited to sensing single frequencies with negligible temporal fluctuations. Nuclear Magnetic Resonance (NMR) signals from molecules often contain multifrequency components and sensing them using PEA is ruled out. Here we propose an alternative method for precision magnetometry in frequency multiplexed signals via compressive sensing (CS) techniques focusing on nanoscale NMR. We show that CS can provide for precision scaling approximately as σB ≈ 1/T, as well as for a 5-fold increase in sensitivity over dynamic-range gain, in addition to reducing the total number of resources required. We illustrate our method by taking model solid-state spectra of Glycine acquired under Magic Angle Spinning conditions.

  6. Efficient route to high-bandwidth nanoscale magnetometry using single spins in diamond.

    PubMed

    Puentes, Graciana; Waldherr, Gerald; Neumann, Philipp; Balasubramanian, Gopalakrishnan; Wrachtrup, Jörg

    2014-01-01

    Nitrogen-vacancy (NV) center in diamond is a promising quantum metrology tool finding applications across disciplines. The spin sensor measures magnetic fields, electric fields and temperature with nano-scale precision and is fully operable under ambient conditions. Moreover, it achieves precision scaling inversely with total measurement time σB ∝ 1/T (Heisenberg scaling) rather than as the inverse of the square root of T, with σB = √T the Shot-Noise limit. This scaling can be achieved by means of phase estimation algorithms (PEAs), in combination with single-shot read-out. Despite their accuracy, the range of applicability of PEAs is limited to sensing single frequencies with negligible temporal fluctuations. Nuclear Magnetic Resonance (NMR) signals from molecules often contain multifrequency components and sensing them using PEA is ruled out. Here we propose an alternative method for precision magnetometry in frequency multiplexed signals via compressive sensing (CS) techniques focusing on nanoscale NMR. We show that CS can provide for precision scaling approximately as σB ≈ 1/T, as well as for a 5-fold increase in sensitivity over dynamic-range gain, in addition to reducing the total number of resources required. We illustrate our method by taking model solid-state spectra of Glycine acquired under Magic Angle Spinning conditions. PMID:24728454

  7. Symmetry-lowering lattice distortion at the spin reorientation in MnBi single crystals

    SciTech Connect

    McGuire, Michael A.; Cao, Huibo; Chakoumakos, Bryan C.; Sales, Brian C.

    2014-11-18

    Here we report structural and physical properties determined by measurements on large single crystals of the anisotropic ferromagnet MnBi. The findings support the importance of magnetoelastic effects in this material. X-ray diffraction reveals a structural phase transition at the spin reorientation temperature TSR = 90 K. The distortion is driven by magneto-elastic coupling, and upon cooling transforms the structure from hexagonal to orthorhombic. Heat capacity measurements show a thermal anomaly at the crystallographic transition, which is suppressed rapidly by applied magnetic fields. Effects on the transport and anisotropic magnetic properties of the single crystals are also presented. Increasing anisotropy of the atomic displacement parameters for Bi with increasing temperature above TSR is revealed by neutron diffraction measurements. It is likely that this is directly related to the anisotropic thermal expansion in MnBi, which plays a key role in the spin reorientation and magnetocrystalline anisotropy. Finally, the identification of the true ground state crystal structure reported here may be important for future experimental and theoretical studies of this permanent magnet material, which have to date been performed and interpreted using only the high temperature structure.

  8. Symmetry-lowering lattice distortion at the spin reorientation in MnBi single crystals

    NASA Astrophysics Data System (ADS)

    McGuire, Michael A.; Cao, Huibo; Chakoumakos, Bryan C.; Sales, Brian C.

    2014-11-01

    Structural and physical properties determined by measurements on large single crystals of the anisotropic ferromagnet MnBi are reported. The findings support the importance of magnetoelastic effects in this material. X-ray diffraction reveals a structural phase transition at the spin reorientation temperature TS R=90 K. The distortion is driven by magnetoelastic coupling, and upon cooling transforms the structure from hexagonal to orthorhombic. Heat capacity measurements show a thermal anomaly at the crystallographic transition, which is suppressed rapidly by applied magnetic fields. Effects on the transport and anisotropic magnetic properties of the single crystals are also presented. Increasing anisotropy of the atomic displacement parameters for Bi with increasing temperature above TS R is revealed by neutron diffraction measurements. It is likely that this is directly related to the anisotropic thermal expansion in MnBi, which plays a key role in the spin reorientation and magnetocrystalline anisotropy. The identification of the true ground-state crystal structure reported here may be important for future experimental and theoretical studies of this permanent magnet material, which have to date been performed and interpreted using only the high-temperature structure.

  9. Electron Spin Resonance Experiments on a Single Electron in Silicon Implanted with Phosphorous

    NASA Astrophysics Data System (ADS)

    Luhman, Dwight R.; Nguyen, K.; Tracy, L. A.; Carr, S.; Borchardt, J.; Bishop, N.; Ten Eyck, G.; Pluym, T.; Wendt, J.; Lilly, M. P.; Carroll, M. S.

    2015-03-01

    In this talk we will discuss the results of our ongoing experiments involving electron spin resonance (ESR) on a single electron in a natural silicon sample. The sample consists of an SET, defined by lithographic polysilicon gates, coupled to nearby phosphorous donors. The SET is used to detect charge transitions and readout the spin of the electron being investigated with ESR. The measurements were done with the sample at dilution refrigerator temperatures in the presence of a 1.3 T magnetic field. We will present data demonstrating Rabi oscillations of a single electron in this system as well as measurements of the coherence time, T2. We will also discuss our results using these and various other pulsing schemes in the context of a donor-SET system. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE Office of Basic Energy Sciences user facility. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

  10. Efficient route to high-bandwidth nanoscale magnetometry using single spins in diamond

    NASA Astrophysics Data System (ADS)

    Puentes, Graciana; Waldherr, Gerald; Neumann, Philipp; Balasubramanian, Gopalakrishnan; Wrachtrup, Jörg

    2014-04-01

    Nitrogen-vacancy (NV) center in diamond is a promising quantum metrology tool finding applications across disciplines. The spin sensor measures magnetic fields, electric fields and temperature with nano-scale precision and is fully operable under ambient conditions. Moreover, it achieves precision scaling inversely with total measurement time σB ~ 1/T (Heisenberg scaling) rather than as the inverse of the square root of T, with the Shot-Noise limit. This scaling can be achieved by means of phase estimation algorithms (PEAs), in combination with single-shot read-out. Despite their accuracy, the range of applicability of PEAs is limited to sensing single frequencies with negligible temporal fluctuations. Nuclear Magnetic Resonance (NMR) signals from molecules often contain multifrequency components and sensing them using PEA is ruled out. Here we propose an alternative method for precision magnetometry in frequency multiplexed signals via compressive sensing (CS) techniques focusing on nanoscale NMR. We show that CS can provide for precision scaling approximately as σB ~ 1/T, as well as for a 5-fold increase in sensitivity over dynamic-range gain, in addition to reducing the total number of resources required. We illustrate our method by taking model solid-state spectra of Glycine acquired under Magic Angle Spinning conditions.

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

    PubMed

    Wei, Hai-Rui; Deng, Fu-Guo

    2014-01-13

    We present some compact quantum circuits for a deterministic quantum computing on electron-spin qubits assisted by quantum dots inside single-side optical microcavities, including the CNOT, Toffoli, and Fredkin gates. They are constructed by exploiting the giant optical Faraday rotation induced by a single-electron spin in a quantum dot inside a single-side optical microcavity as a result of cavity quantum electrodynamics. Our universal quantum gates have some advantages. First, all the gates are accomplished with a success probability of 100% in principle. Second, our schemes require no additional electron-spin qubits and they are achieved by some input-output processes of a single photon. Third, our circuits for these gates are simple and economic. Moreover, our devices for these gates work in both the weak coupling and the strong coupling regimes, and they are feasible in experiment. PMID:24515020

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

    PubMed

    Wei, Hai-Rui; Deng, Fu-Guo

    2014-01-13

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

  13. Polarization control at spin-driven ferroelectric domain walls.

    PubMed

    Leo, Naëmi; Bergman, Anders; Cano, Andres; Poudel, Narayan; Lorenz, Bernd; Fiebig, Manfred; Meier, Dennis

    2015-01-01

    Unusual electronic states arise at ferroelectric domain walls due to the local symmetry reduction, strain gradients and electrostatics. This particularly applies to improper ferroelectrics, where the polarization is induced by a structural or magnetic order parameter. Because of the subordinate nature of the polarization, the rigid mechanical and electrostatic boundary conditions that constrain domain walls in proper ferroics are lifted. Here we show that spin-driven ferroelectricity promotes the emergence of charged domain walls. This provides new degrees of flexibility for controlling domain-wall charges in a deterministic and reversible process. We create and position a domain wall by an electric field in Mn0.95Co0.05WO4. With a magnetic field we then rotate the polarization and convert neutral into charged domain walls, while its magnetic properties peg the wall to its location. Using atomistic Landau-Lifshitz-Gilbert simulations we quantify the polarization changes across the two wall types and highlight their general occurrence. PMID:25868608

  14. Approaching the ground states of the random maximum two-satisfiability problem by a greedy single-spin flipping process

    NASA Astrophysics Data System (ADS)

    Ma, Hui; Zhou, Haijun

    2011-05-01

    In this brief report we explore the energy landscapes of two spin glass models using a greedy single-spin flipping process, Gmax. The ground-state energy density of the random maximum two-satisfiability problem is efficiently approached by Gmax. The achieved energy density e(t) decreases with the evolution time t as e(t)-e(∞)=h(log10t)-z with a small prefactor h and a scaling coefficient z>1, indicating an energy landscape with deep and rugged funnel-shape regions. For the ±J Viana-Bray spin glass model, however, the greedy single-spin dynamics quickly gets trapped to a local minimal region of the energy landscape.

  15. Voltage-controllable generator of pure spin current: A three-terminal model

    SciTech Connect

    Ma, Zheng; Wu, Reng-Lai; Yu, Ya-Bin Wang, Miao

    2014-07-28

    Three-terminal devices have been frequently proposed to generate the pure spin current. However, the controllability and stability of pure spin current still needs to be improved. In this paper, a three-terminal device, composed of a ferromagnetic metallic lead and two nonmagnetic semiconductor leads coupled with a quantum dot, is employed to study the properties of electron spin transport. The results show that when the external voltage on one of nonmagnetic semiconductor leads is adjusted to a proper range, a pure spin current plateau or a fully spin-polarized current plateau appears in another nonmagnetic semiconductor lead. In a wide range of external voltage, the pure spin current or the spin-polarized current is kept unchanged. Since the change of temperature may considerably influence the spin-polarization of current and is inevitable actually, we studied the corresponding compensation to keep the pure spin current unchanged. Furthermore, the effect of device parameters on the pure spin current is also investigated.

  16. Spin-lattice relaxation via quantum tunneling in diluted crystals of Fe4 single-molecule magnets

    NASA Astrophysics Data System (ADS)

    Repollés, A.; Cornia, A.; Luis, F.

    2014-02-01

    We investigate the dynamic susceptibility of Fe4 single-molecule magnets with integer spin (S =5) in the form of pure crystals as well as diluted in crystals of isostructural, but nonmagnetic, Ga4 clusters. Below approximately 1 K, the spin-lattice relaxation becomes dominated by a temperature-independent process. The spin-lattice relaxation time τ measured in this "quantum regime" is 12 orders of magnitude shorter than the characteristic time scale of direct phonon-induced processes but agrees with the relaxation times of pure (i.e., not assisted by phonons) spin tunneling events. The present results show that the latter phenomenon, despite conserving the energy of the ensemble of electronic and nuclear spins, drives the thermalization of electronic spins at very low temperatures. The spin-lattice relaxation time scales with the concentration of Fe4, thus suggesting that the main effect of dipolar interactions is to block tunneling. The data show therefore no evidence for the contribution of collective phonon emission processes, such as phonon superradiance, to the spin-lattice relaxation.

  17. Demonstration of quantum entanglement between a single electron spin confined to an InAs quantum dot and a photon.

    PubMed

    Schaibley, J R; Burgers, A P; McCracken, G A; Duan, L-M; Berman, P R; Steel, D G; Bracker, A S; Gammon, D; Sham, L J

    2013-04-19

    The electron spin state of a singly charged semiconductor quantum dot has been shown to form a suitable single qubit for quantum computing architectures with fast gate times. A key challenge in realizing a useful quantum dot quantum computing architecture lies in demonstrating the ability to scale the system to many qubits. In this Letter, we report an all optical experimental demonstration of quantum entanglement between a single electron spin confined to a single charged semiconductor quantum dot and the polarization state of a photon spontaneously emitted from the quantum dot's excited state. We obtain a lower bound on the fidelity of entanglement of 0.59±0.04, which is 84% of the maximum achievable given the timing resolution of available single photon detectors. In future applications, such as measurement-based spin-spin entanglement which does not require sub-nanosecond timing resolution, we estimate that this system would enable near ideal performance. The inferred (usable) entanglement generation rate is 3×10(3) s(-1). This spin-photon entanglement is the first step to a scalable quantum dot quantum computing architecture relying on photon (flying) qubits to mediate entanglement between distant nodes of a quantum dot network.

  18. Suppression of Walker breakdown in magnetic domain wall propagation through structural control of spin wave emission

    NASA Astrophysics Data System (ADS)

    Burn, David M.; Atkinson, Del

    2013-06-01

    The control of individual magnetic domain walls has potential for future spintronic memory and data processing applications. The speed and reliability of such devices are determined by the dynamic properties of the domain walls. Typically, spin precession limitations lead to Walker breakdown, limiting wall velocity resulting in low mobility. Here, we show the suppression of Walker breakdown by the careful design of small amplitude periodic nanowire structuring to match the periodicity of domain wall spin structure transformations. This opens up a channel for energy dissipation via spin wave emission, allowing a domain wall to maintain its spin structure during propagation.

  19. Electrically-Controllable Spin Spatial Splitter in a Novel Magnetic Nanostructure

    NASA Astrophysics Data System (ADS)

    Shen, Li-Hua; Ma, Wen-Yue; Liu, Gui-Xiang

    2016-08-01

    Based on a novel magnetic nanostructure with zero average magnetic field, a spin spatial splitter was recently proposed. This paper reports on how to effectively manipulate this device using a transverse electrical field with an applied bias. With the help of the stationary phase method, the lateral displacement and its spin polarization are calculated for the electron across this device. Both magnitude and sign of spin polarization are found to vary sensitively with this applied electric field. Thus, this device can be controlled conveniently by electric means, and can consequently serve as an electrically-tunable spin spatial splitter for spintronics applications.

  20. Spin-controlled orbital motion in tightly focused high-order Laguerre-Gaussian beams.

    PubMed

    Cao, Yongyin; Zhu, Tongtong; Lv, Haiyi; Ding, Weiqiang

    2016-02-22

    Spin angular momentum can contribute to both optical force and torque exerted on spheres. Orbit rate of spheres located in tightly focused LG beams with the same azimuthal mode index l is spin-controlled due to spin-orbit coupling. Laguerre-Gaussian beams with high-order azimuthal mode are used here to study the orbit rate of dielectric spheres. Orbit rates of spheres with varying sizes and refravtive indices are investigated as well as optical forces acting on spheres in LG beams with different azimuthal modes. These results would be much helpful to investigation on optical rotation and transfer of spin and orbital angular momentum. PMID:26906996

  1. Magnetic field control of the spin Seebeck effect

    NASA Astrophysics Data System (ADS)

    Ritzmann, Ulrike; Hinzke, Denise; Kehlberger, Andreas; Guo, Er-Jia; Kläui, Mathias; Nowak, Ulrich

    2015-11-01

    The origin of the suppression of the longitudinal spin Seebeck effect by applied magnetic fields is studied. We perform numerical simulations of the stochastic Landau-Lifshitz-Gilbert equation of motion for an atomistic spin model and calculate the magnon accumulation in linear temperature gradients for different strengths of applied magnetic fields and different length scales of the temperature gradient. We observe a decrease of the magnon accumulation with increasing magnetic field and we reveal that the origin of this effect is a field dependent change of the frequency distribution of the propagating magnons. With increasing field the magnonic spin currents are reduced due to a suppression of parts of the frequency spectrum. By comparison with measurements of the magnetic field dependent longitudinal spin Seebeck effect in YIG thin films with various thicknesses, we find qualitative agreement between our model and the experimental data, demonstrating the importance of this effect for experimental systems.

  2. Controlling spin lifetime with Dresselhaus and Rashba fields in the 2D semiconductor MX

    NASA Astrophysics Data System (ADS)

    Appelbaum, Ian; Li, Pengke

    It is widely believed that whenever spin encodes logic state in a semiconductor device, transport channel materials with the longest spin lifetime are the most suitable choice. However, once a logic operation is completed, residual spins can and will interfere with those involved in future operations. We propose to solve this problem by utilizing the unique properties of spin-orbit effects in the electronic structure of monolayer of group-III metal-monochalcogenide (MX) semiconductors. The interplay of Dresselhaus and Rashba effective magnetic fields in these materials will be shown to provide effective external control over spin polarization lifetime, potentially useful for future spin-enabled digital devices. Based upon: Pengke Li and Ian Appelbaum, arXiv:1508.06963 (to appear in Phys. Rev. B). We acknowledge support from NSF, DTRA, and ONR.

  3. Photospintronics: Magnetic Field-Controlled Photoemission and Light-Controlled Spin Transport in Hybrid Chiral Oligopeptide-Nanoparticle Structures

    PubMed Central

    2016-01-01

    The combination of photonics and spintronics opens new ways to transfer and process information. It is shown here that in systems in which organic molecules and semiconductor nanoparticles are combined, matching these technologies results in interesting new phenomena. We report on light induced and spin-dependent charge transfer process through helical oligopeptide–CdSe nanoparticles’ (NPs) architectures deposited on ferromagnetic substrates with small coercive force (∼100–200 Oe). The spin control is achieved by the application of the chirality-induced spin-dependent electron transfer effect and is probed by two different methods: spin-controlled electrochemichemistry and photoluminescence (PL) at room temperature. The injected spin could be controlled by excitation of the nanoparticles. By switching the direction of the magnetic field of the substrate, the PL intensity could be alternated. PMID:27027885

  4. Electric control of superconducting transition through a spin-orbit coupled interface.

    PubMed

    Ouassou, Jabir Ali; Di Bernardo, Angelo; Robinson, Jason W A; Linder, Jacob

    2016-01-01

    We demonstrate theoretically all-electric control of the superconducting transition temperature using a device comprised of a conventional superconductor, a ferromagnetic insulator, and semiconducting layers with intrinsic spin-orbit coupling. By using analytical calculations and numerical simulations, we show that the transition temperature of such a device can be controlled by electric gating which alters the ratio of Rashba to Dresselhaus spin-orbit coupling. The results offer a new pathway to control superconductivity in spintronic devices. PMID:27426887

  5. Electric control of superconducting transition through a spin-orbit coupled interface.

    PubMed

    Ouassou, Jabir Ali; Di Bernardo, Angelo; Robinson, Jason W A; Linder, Jacob

    2016-07-18

    We demonstrate theoretically all-electric control of the superconducting transition temperature using a device comprised of a conventional superconductor, a ferromagnetic insulator, and semiconducting layers with intrinsic spin-orbit coupling. By using analytical calculations and numerical simulations, we show that the transition temperature of such a device can be controlled by electric gating which alters the ratio of Rashba to Dresselhaus spin-orbit coupling. The results offer a new pathway to control superconductivity in spintronic devices.

  6. Electric control of superconducting transition through a spin-orbit coupled interface

    NASA Astrophysics Data System (ADS)

    Ouassou, Jabir Ali; di Bernardo, Angelo; Robinson, Jason W. A.; Linder, Jacob

    2016-07-01

    We demonstrate theoretically all-electric control of the superconducting transition temperature using a device comprised of a conventional superconductor, a ferromagnetic insulator, and semiconducting layers with intrinsic spin-orbit coupling. By using analytical calculations and numerical simulations, we show that the transition temperature of such a device can be controlled by electric gating which alters the ratio of Rashba to Dresselhaus spin-orbit coupling. The results offer a new pathway to control superconductivity in spintronic devices.

  7. Electric control of superconducting transition through a spin-orbit coupled interface

    PubMed Central

    Ouassou, Jabir Ali; Di Bernardo, Angelo; Robinson, Jason W. A.; Linder, Jacob

    2016-01-01

    We demonstrate theoretically all-electric control of the superconducting transition temperature using a device comprised of a conventional superconductor, a ferromagnetic insulator, and semiconducting layers with intrinsic spin-orbit coupling. By using analytical calculations and numerical simulations, we show that the transition temperature of such a device can be controlled by electric gating which alters the ratio of Rashba to Dresselhaus spin-orbit coupling. The results offer a new pathway to control superconductivity in spintronic devices. PMID:27426887

  8. Maximized orbital and spin Kondo effects in a single-electron transistor

    NASA Astrophysics Data System (ADS)

    Le Hur, Karyn; Simon, Pascal; Borda, László

    2004-01-01

    We investigate the charge fluctuations of a single-electron box (metallic grain) coupled to a lead via a smaller quantum dot in the Kondo regime. The most interesting aspect of this problem resides in the interplay between spin Kondo physics stemming from the screening of the spin of the small dot and orbital Kondo physics emerging when charging states of the grain with (charge) Q=0 and Q=e are almost degenerate. Combining Wilson’s numerical renormalization-group method with perturbative scaling approaches we push forward our previous work [K. Le Hur and P. Simon, Phys. Rev. B 67, 201308R (2003)]. We emphasize that, for symmetric and slightly asymmetric barriers, the strong entanglement of charge and spin flip events in this setup inevitably results in a nontrivial stable SU(4) Kondo fixed point near the degeneracy points of the grain. By analogy with a small dot sandwiched between two leads, the ground state is Fermi-liquid-like, which considerably smears out the Coulomb staircase behavior and prevents the Matveev logarithmic singularity from arising. Most notably, the associated Kondo temperature TSU(4)K might be raised compared to that in conductance experiments through a small quantum dot (˜1 K), which makes the observation of our predictions a priori accessible. We discuss the robustness of the SU(4) correlated state against the inclusion of an external magnetic field, a deviation from the degeneracy points, particle-hole symmetry in the small dot, and asymmetric tunnel junctions and comment on the different crossovers.

  9. Phase-controllable spin wave generation in iron garnet by linearly polarized light pulses

    SciTech Connect

    Yoshimine, Isao; Iida, Ryugo; Shimura, Tsutomu; Satoh, Takuya; Stupakiewicz, Andrzej; Maziewski, Andrzej

    2014-07-28

    A phase-controlled spin wave was non-thermally generated in bismuth-doped rare-earth iron garnet by linearly polarized light pulses. We controlled the initial phase of the spin wave continuously within a range of 180° by changing the polarization azimuth of the excitation light. The azimuth dependences of the initial phase and amplitude of the spin wave were attributed to a combination of the inverse Cotton-Mouton effect and photoinduced magnetic anisotropy. Temporally and spatially resolved spin wave propagation was observed with a CCD camera, and the waveform was in good agreement with calculations. A nonlinear effect of the spin excitation was observed for excitation fluences higher than 100 mJ/cm{sup 2}.

  10. Controlling orbital-selective Kondo effects in a single molecule through coordination chemistry

    SciTech Connect

    Tsukahara, Noriyuki; Kawai, Maki; Takagi, Noriaki; Minamitani, Emi; Kim, Yousoo

    2014-08-07

    Iron(II) phthalocyanine (FePc) molecule causes novel Kondo effects derived from the unique electronic structure of multi-spins and multi-orbitals when attached to Au(111). Two unpaired electrons in the d{sub z}{sup 2} and the degenerate dπ orbitals are screened stepwise, resulting in spin and spin+orbital Kondo effects, respectively. We investigated the impact on the Kondo effects of the coordination of CO and NO molecules to the Fe{sup 2+} ion as chemical stimuli by using scanning tunneling microscopy (STM) and density functional theory calculations. The impacts of the two diatomic molecules are different from each other as a result of the different electronic configurations. The coordination of CO converts the spin state from triplet to singlet, and then the Kondo effects completely disappear. In contrast, an unpaired electron survives in the molecular orbital composed of Fe d{sub z}{sup 2} and NO 5σ and 2π* orbitals for the coordination of NO, causing a sharp Kondo resonance. The isotropic magnetic response of the peak indicates the origin is the spin Kondo effect. The diatomic molecules attached to the Fe{sup 2+} ion were easily detached by applying a pulsed voltage at the STM junction. These results demonstrate that the single molecule chemistry enables us to switch and control the spin and the many-body quantum states reversibly.

  11. Processing, spinning, and fabrication of continuous fibers of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Booker, Richard Delane

    Single-walled carbon nanotubes (SWNTs) show great promise for use in a wide range of applications. One of the most promising avenues for attaining these applications is the dispersion of SWNTs at high concentrations in superacids and processing into macroscopic articles such as fibers or films. Fibers spun from SWNT/superacid dispersions indicate that the morphology of the starting SWNT material influences the final morphology of the as-spun fiber. Here, we describe a method (termed disentanglement) of dispersing SWNTs in superacids and treating them using a high-shear, rotor/stator homogenizer, followed by coagulation to recover the solid SWNT material for use in fiber spinning. Several lines of experimental evidence (rheology and optical microscopy of the SWNTs in solution, scanning electron microscopy (SEM) of the coagulated material, and SEM of fibers spun from the coagulated material) show that this disentanglement treatment radically improves the degree of alignment in the SWNTs' morphology, which in turn improves the dispersibility and processability. Raman microscopy and thermogravimetric analysis (TGA) before and after homogenization show that the treatment does not damage the SWNTs. Although this technique is particularly important as a pre-processing step for fiber spinning of neat SWNT fibers, it is also useful for neat SWNT films, SWNT/polymer composites, and surfactant- or polymer-stabilized SWNT dispersions. Macroscopic neat SWNT fibers were successfully produced and characterized. Studies on coagulated fiber morphology suggest that slow acid removal is crucial to minimizing voids. Better SWNT coalescence and alignment were obtained by using appropriate coagulant and dope concentration. SWNTs were disentangled and dissolved at high concentrations (8 - 10 wt%) in 102% sulfuric acid. Fibers were subsequently extruded by dry-jet wet spinning into ice water and polyvinyl alcohol (PVA) / ice water. Drawing the fiber continuously while spinning further

  12. Predictions on the Transverse Single-Spin Asymmetries at Subleading Twist of Pion Production in Semi-Inclusive DIS

    NASA Astrophysics Data System (ADS)

    Mao, Wenjuan; Lu, Zhun; Ma, Bo-Qiang

    2016-02-01

    We estimate the single-spin asymmetries with sin ϕS and sin(2ϕh ‑ ϕS) angular dependencies for electroproduction of pions in transversely polarized semi-inclusive DIS process. We consider the effect of the twist-3 transverse momentum dependent distributions which convoluted with twist-2 fragmentation functions. We calculate these distributions in a spectator-diquark model, and predict the corresponding single-spin asymmetries at the kinematics of HERMES, JLab and COMPASS. We find that the numerical estimates show that the asymmetries are sizable, and the T-odd twist-3 TMDs play an important role in these asymmetries.

  13. Single gimbal/strapdown inertial navigation system for use on spin stabilized flight test vehicles

    SciTech Connect

    Watts, A.C.; Andreas, R.D.

    1980-01-01

    A hybrid strapdown inertial navigation system intended for use on spin stabilized flight test vehicles is described. The configuration of the navigator which is briefly described consists of three floated rate integrating gyros, one of which is used in conjunction with the gimbal with the remaining two operated in a rate gyro mode. Outputs from the two strapdown gyros and three accelerometers are digitized and processed by a high performance computer. The navigation algorithms utilize a direction cosine matrix formulation for the attitude computation implemented in the digital computer. The implementation of this algorithm for the single gimbal configuration is described. An accuracy model and results for a reentry vehicle flight test trajectory are presented. The flight test performance from launch to reentry is presented.

  14. Single-spin asymmetries in the leptoproduction of transversely polarized Λ hyperons

    DOE PAGES

    Kanazawa, K.; Metz, A.; Pitonyak, D.; Schlegel, M.

    2015-04-13

    We analyze single-spin asymmetries (SSAs) in the leptoproduction of transversely polarized Λ hyperons within the collinear twist-3 formalism. We calculate both the distribution and fragmentation terms in two different gauges (lightcone and Feynman) and show that the results are identical. This is the first time that the fragmentation piece has been analyzed for transversely polarized hadron production within the collinear twist-3 framework. In lightcone gauge we use the same techniques that were employed in computing the analogous piece in p↑ p → π X, which has become an important part to that reaction. With this in mind, we also verifymore » the gauge invariance of the formulas for the transverse SSA in the leptoproduction of pions. (author)« less

  15. Single-spin asymmetries in the leptoproduction of transversely polarized Λ hyperons

    SciTech Connect

    Kanazawa, K.; Metz, A.; Pitonyak, D.; Schlegel, M.

    2015-04-13

    We analyze single-spin asymmetries (SSAs) in the leptoproduction of transversely polarized Λ hyperons within the collinear twist-3 formalism. We calculate both the distribution and fragmentation terms in two different gauges (lightcone and Feynman) and show that the results are identical. This is the first time that the fragmentation piece has been analyzed for transversely polarized hadron production within the collinear twist-3 framework. In lightcone gauge we use the same techniques that were employed in computing the analogous piece in p↑ p → π X, which has become an important part to that reaction. With this in mind, we also verify the gauge invariance of the formulas for the transverse SSA in the leptoproduction of pions. (author)

  16. Longitudinal double spin asymmetries in single hadron quasi-real photoproduction at high pT

    NASA Astrophysics Data System (ADS)

    Adolph, C.; Akhunzyanov, R.; Alexeev, M. G.; Alexeev, G. D.; Amoroso, A.; Andrieux, V.; Anosov, V.; Augustyniak, W.; Austregesilo, A.; Azevedo, C. D. R.; Badełek, B.; Balestra, F.; Barth, J.; Beck, R.; Bedfer, Y.; Bernhard, J.; Bicker, K.; Bielert, E. R.; Birsa, R.; Bisplinghoff, J.; Bodlak, M.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Büchele, M.; Burtin, E.; Chang, W.-C.; Chiosso, M.; Choi, I.; Chung, S.-U.; Cicuttin, A.; Crespo, M. L.; Curiel, Q.; Dalla Torre, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O. Yu.; Dhara, L.; Donskov, S. V.; Doshita, N.; Duic, V.; Dünnweber, W.; Dziewiecki, M.; Efremov, A.; Eversheim, P. D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Finger, M.; Finger, M.; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Fuchey, E.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Giordano, F.; Gnesi, I.; Gorzellik, M.; Grabmüller, S.; Grasso, A.; Grosse Perdekamp, M.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Haas, F.; Hahne, D.; von Harrach, D.; Hashimoto, R.; Heinsius, F. H.; Herrmann, F.; Hinterberger, F.; Horikawa, N.; d'Hose, N.; Hsieh, C.-Y.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Joosten, R.; Jörg, P.; Kabuß, E.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Kotzinian, A. M.; Kouznetsov, O.; Krämer, M.; Kremser, P.; Krinner, F.; Kroumchtein, Z. V.; Kuchinski, N.; Kuhn, R.; Kunne, F.; Kurek, K.; Kurjata, R. P.; Lednev, A. A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lichtenstadt, J.; Longo, R.; Maggiora, A.; Magnon, A.; Makins, N.; Makke, N.; Mallot, G. K.; Marchand, C.; Marianski, B.; Martin, A.; Marzec, J.; Matoušek, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Miyachi, Y.; Montuenga, P.; Nagaytsev, A.; Nerling, F.; Neyret, D.; Nikolaenko, V. I.; Nový, J.; Nowak, W.-D.; Nukazuka, G.; Nunes, A. S.; Olshevsky, A. G.; Orlov, I.; Ostrick, M.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peng, J.-C.; Pereira, F.; Pešek, M.; Peshekhonov, D. V.; Platchkov, S.; Pochodzalla, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Riedl, C.; Rossiyskaya, N. S.; Ryabchikov, D. I.; Rychter, A.; Samoylenko, V. D.; Sandacz, A.; Santos, C.; Sarkar, S.; Savin, I. A.; Sbrizzai, G.; Schiavon, P.; Schmidt, K.; Schmieden, H.; Schönning, K.; Schopferer, S.; Selyunin, A.; Shevchenko, O. Yu.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Sozzi, F.; Srnka, A.; Stolarski, M.; Sulc, M.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Tosello, F.; Tskhay, V.; Uhl, S.; Veloso, J.; Virius, M.; Weisrock, T.; Wilfert, M.; ter Wolbeek, J.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zink, A.

    2016-02-01

    We measured the longitudinal double spin asymmetries ALL for single hadron muoproduction off protons and deuterons at photon virtuality Q2 < 1(GeV / c) 2 for transverse hadron momenta pT in the range 1 GeV / c to 4 GeV / c. They were determined using COMPASS data taken with a polarised muon beam of 160 GeV / c or 200 GeV / c impinging on polarised 6LiD or NH3 targets. The experimental asymmetries are compared to next-to-leading order pQCD calculations, and are sensitive to the gluon polarisation ΔG inside the nucleon in the range of the nucleon momentum fraction carried by gluons 0.05

  17. Single-Spin Asymmetries AULsinϕh in Semi-Inclusive Pions Production

    NASA Astrophysics Data System (ADS)

    Lu, Zhun; Mao, Wenjuan

    2016-02-01

    The single-spin asymmetry AULsinϕh of charged and neutral pion production in semi-inclusive deep-inelastic scattering on longitudinally polarized nucleon targets is studied. We particularly consider the effects of the twist-3 transverse-momentum dependent distribution functions fL⊥ and hL, which are calculated in two different spectator-diquark models. We estimate the asymmetry for π+, π‑ and π0 produced off the proton target at HERMES and compare the results with the HERMES measurements. We also predict the same asymmetric moment for different pions at the kinematics of CLAS 5.5 GeV on a proton target, as well as at COMPASS on a deuteron target for comparison.

  18. Single-shot quantum nondemolition measurement of a quantum-dot electron spin using cavity exciton-polaritons

    NASA Astrophysics Data System (ADS)

    Puri, Shruti; McMahon, Peter L.; Yamamoto, Yoshihisa

    2014-10-01

    We propose a scheme to perform single-shot quantum nondemolition (QND) readout of the spin of an electron trapped in a semiconductor quantum dot (QD). Our proposal relies on the interaction of the QD electron spin with optically excited, quantum well (QW) microcavity exciton-polaritons. The spin-dependent Coulomb exchange interaction between the QD electron and cavity polaritons causes the phase and intensity response of left circularly polarized light to be different than that of right circularly polarized light, in such a way that the QD electron's spin can be inferred from the response to a linearly polarized probe reflected or transmitted from the cavity. We show that with careful device design it is possible to essentially eliminate spin-flip Raman transitions. Thus a QND measurement of the QD electron spin can be performed within a few tens of nanoseconds with fidelity ˜99.95%. This improves upon current optical QD spin readout techniques across multiple metrics, including speed and scalability.

  19. Controlled synthesis of single-crystalline graphene

    SciTech Connect

    Xueshen, Wang Jinjin, Li Qing, Zhong; Yuan, Zhong; Mengke, Zhao; Yonggang, Liu

    2014-03-15

    This paper reports the controlled synthesis of single-crystalline graphene on the back side of copper foil using CH{sub 4} as the precursor. The influence of growth time and the pressure ratio of CH{sub 4}/H{sub 2} on the structure of graphene are examined. An optimized polymer-assisted method is used to transfer the synthesized graphene onto a SiO{sub 2}/Si substrate. Scanning electron microscopy and Raman spectroscopy are used to characterize the graphene.

  20. Quasidegenerate scaled opposite spin second order perturbation corrections to single excitation configuration interaction

    NASA Astrophysics Data System (ADS)

    Casanova, David; Rhee, Young Min; Head-Gordon, Martin

    2008-04-01

    Scaled opposite spin (SOS) second order perturbative corrections to single excitation configuration interaction (CIS) are extended to correctly treat quasidegeneracies between excited states. Two viable methods, termed as SOS-CIS(D0) and SOS-CIS(D1), are defined, implemented, and tested. Each involves one empirical parameter (plus a second for the SOS-MP2 ground state), has computational cost that scales with the fourth power of molecule size, and has storage requirements that are cubic, with only quantities of the rank of single excitations produced and stored during iterations. Tests on a set of low-lying adiabatic valence excitation energies and vertical Rydberg excitations of organic and inorganic molecules show that the empirical parameter can be acceptably transferred from the corresponding nondegenerate perturbation theories without any further fitting. Further tests on higher excited states show that the new methods correctly perform for surface crossings for which nondegenerate approaches fail. Numerical results show that SOS-CIS(D0) appears to treat Rydberg excitations in a more balanced way than SOS-CIS(D1) and is, therefore, likely to be the preferred approach. It should be useful for exploring excited state geometries, transition structures, and conical intersections for states of medium to large organic molecules that are dominated by single excitations.

  1. Controlling the Spins Angular Momentum in Ferromagnets with Sequences of Picosecond Acoustic Pulses

    PubMed Central

    Kim, Ji-Wan; Vomir, Mircea; Bigot, Jean-Yves

    2015-01-01

    Controlling the angular momentum of spins with very short external perturbations is a key issue in modern magnetism. For example it allows manipulating the magnetization for recording purposes or for inducing high frequency spin torque oscillations. Towards that purpose it is essential to modify and control the angular momentum of the magnetization which precesses around the resultant effective magnetic field. That can be achieved with very short external magnetic field pulses or using intrinsically coupled magnetic structures, resulting in a transfer of spin torque. Here we show that using picosecond acoustic pulses is a versatile and efficient way of controlling the spin angular momentum in ferromagnets. Two or three acoustic pulses, generated by femtosecond laser pulses, allow suppressing or enhancing the magnetic precession at any arbitrary time by precisely controlling the delays and amplitudes of the optical pulses. A formal analogy with a two dimensional pendulum allows us explaining the complex trajectory of the magnetic vector perturbed by the acoustic pulses. PMID:25687970

  2. Controlling the spins angular momentum in ferromagnets with sequences of picosecond acoustic pulses.

    PubMed

    Kim, Ji-Wan; Vomir, Mircea; Bigot, Jean-Yves

    2015-02-17

    Controlling the angular momentum of spins with very short external perturbations is a key issue in modern magnetism. For example it allows manipulating the magnetization for recording purposes or for inducing high frequency spin torque oscillations. Towards that purpose it is essential to modify and control the angular momentum of the magnetization which precesses around the resultant effective magnetic field. That can be achieved with very short external magnetic field pulses or using intrinsically coupled magnetic structures, resulting in a transfer of spin torque. Here we show that using picosecond acoustic pulses is a versatile and efficient way of controlling the spin angular momentum in ferromagnets. Two or three acoustic pulses, generated by femtosecond laser pulses, allow suppressing or enhancing the magnetic precession at any arbitrary time by precisely controlling the delays and amplitudes of the optical pulses. A formal analogy with a two dimensional pendulum allows us explaining the complex trajectory of the magnetic vector perturbed by the acoustic pulses.

  3. Electrically controlled spin-transistor operation in a helical magnetic field

    NASA Astrophysics Data System (ADS)

    Wójcik, P.; Adamowski, J.

    2016-03-01

    A proposal of an electrically controlled spin transistor in a helical magnetic field is presented. In the proposed device, the transistor action is driven by the Landau-Zener transitions that lead to a backscattering of spin polarized electrons and switching the transistor into the high-resistance state (off state). The on/off state of the transistor can be controlled by the all-electric means using Rashba spin-orbit coupling that can be tuned by the voltages applied to the side electrodes.

  4. Velocity of the high-spin low-spin interface inside the thermal hysteresis loop of a spin-crossover crystal, via photothermal control of the interface motion.

    PubMed

    Slimani, Ahmed; Varret, François; Boukheddaden, Kamel; Garrot, Damien; Oubouchou, Hassane; Kaizaki, Sumio

    2013-02-22

    We investigated by optical microscopy the thermal transition of the spin-crossover dinuclear iron(II) compound [(Fe(NCSe)(py)(2))(2)(m-bpypz)]. In a high-quality crystal the high-spin (HS) low-spin (LS) thermal transition took place with a sizable hysteresis, at ~108 K and ~116 K on cooling and heating, respectively, through the growth of a single macroscopic domain with a straight LS and HS interface. The interface orientation was almost constant and its propagation velocity was close to ~6 and 26 μ m s(-1) for the on-cooling and on-heating processes, respectively. We found that the motion of the interface was sensitive to the intensity of the irradiation beam of the microscope, through a photothermal effect. By fine-tuning the intensity we could stop and even reverse the interface motion. This way we stabilized a biphasic state of the crystal, and we followed the spontaneous motion of the interface at different temperatures inside the thermal hysteresis loop. This experiment gives access for the first time to an accurate determination of the equilibrium temperature in the case of thermal hysteresis--which was not accessible by the usual quasistatic investigations. The temperature dependence of the propagation velocity inside the hysteretic interval was revealed to be highly nonlinear, and it was quantitatively reproduced by a dynamical mean-field theory, which made possible an estimate of the macroscopic energy barrier.

  5. Dynamics and control of flexible spinning solar sails under reflectivity modulation

    NASA Astrophysics Data System (ADS)

    Mu, Junshan; Gong, Shengping; Ma, Pengbin; Li, Junfeng

    2015-10-01

    Electrochromic devices have been used for the attitude control of a spinning solar sail in a deep space mission by modulating the reflectivity of the sail membrane. As a flexible spinning solar sail has no rigid structure to support its membrane, the distributed load due to solar radiation will lead to the deformation of the sail membrane, and the control torque generated by reflectivity modulation can introduce oscillatory motion to the membrane. By contrast, the deformation and oscillatory motion of the sail membrane have an impact on the performance of the reflectivity control. This paper investigates the dynamics and control of flexible spinning solar sails under reflectivity modulation. The static deformation of a spinning sail membrane subjected to solar radiation pressure in an equilibrium state is analyzed. The von Karman theory is used to obtain the displacements and the stress distribution in the equilibrium states. A simplified analytical first-order mode is chosen to model the membrane oscillation. The coupled membrane oscillation-attitude-orbit dynamics are considered for a GeoSail formation flying mission. The relative attitude and orbit control of flexible spinning solar sails under reflectivity modulation are numerically tested. The simulations indicate that the membrane deformation and oscillation have a lower impact on the control of the reflectivity modulated sails than the increase of the spinning rate.

  6. Electric field control of spin splitting in III-V semiconductor quantum dots without magnetic field

    NASA Astrophysics Data System (ADS)

    Prabhakar, Sanjay; Melnik, Roderick

    2015-10-01

    We provide an alternative means of electric field control for spin manipulation in the absence of magnetic fields by transporting quantum dots adiabatically in the plane of two-dimensional electron gas. We show that the spin splitting energy of moving quantum dots is possible due to the presence of quasi-Hamiltonian that might be implemented to make the next generation spintronic devices of post CMOS technology. Such spin splitting energy is highly dependent on the material properties of semiconductor. It turns out that this energy is in the range of meV and can be further enhanced with increasing pulse frequency. In particular, we show that quantum oscillations in phonon mediated spin-flip behaviors can be observed. We also confirm that no oscillations in spin-flip behaviors can be observed for the pure Rashba or pure Dresselhaus cases.

  7. Coherent spin control of a nanocavity-enhanced qubit in diamond

    DOE PAGES

    Li, Luozhou; Lu, Ming; Schroder, Tim; Chen, Edward H.; Walsh, Michael; Bayn, Igal; Goldstein, Jordan; Gaathon, Ophir; Trusheim, Matthew E.; Mower, Jacob; et al

    2015-01-28

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

  8. Coherent spin control of a nanocavity-enhanced qubit in diamond

    SciTech Connect

    Li, Luozhou; Lu, Ming; Schroder, Tim; Chen, Edward H.; Walsh, Michael; Bayn, Igal; Goldstein, Jordan; Gaathon, Ophir; Trusheim, Matthew E.; Mower, Jacob; Cotlet, Mircea; Markham, Matthew L.; Twitchen, Daniel J.; Englund, Dirk

    2015-01-28

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

  9. Cartesian-Grid Simulations of a Canard-Controlled Missile with a Free-Spinning Tail

    NASA Technical Reports Server (NTRS)

    Murman, Scott M.; Aftosmis, Michael J.; Kwak, Dochan (Technical Monitor)

    2002-01-01

    The proposed paper presents a series of simulations of a geometrically complex, canard-controlled, supersonic missile with free-spinning tail fins. Time-dependent simulations were performed using an inviscid Cartesian-grid-based method with results compared to both experimental data and high-resolution Navier-Stokes computations. At fixed free stream conditions and canard deflections, the tail spin rate was iteratively determined such that the net rolling moment on the empennage is zero. This rate corresponds to the time-asymptotic rate of the free-to-spin fin system. After obtaining spin-averaged aerodynamic coefficients for the missile, the investigation seeks a fixed-tail approximation to the spin-averaged aerodynamic coefficients, and examines the validity of this approximation over a variety of freestream conditions.

  10. Coherent spin control of a nanocavity-enhanced qubit in diamond.

    PubMed

    Li, Luozhou; Schröder, Tim; Chen, Edward H; Walsh, Michael; Bayn, Igal; Goldstein, Jordan; Gaathon, Ophir; Trusheim, Matthew E; Lu, Ming; Mower, Jacob; Cotlet, Mircea; Markham, Matthew L; Twitchen, Daniel J; Englund, Dirk

    2015-01-01

    A central aim of quantum information processing is the efficient entanglement of multiple stationary quantum memories via photons. Among solid-state systems, the nitrogen-vacancy centre in diamond has emerged as an excellent optically addressable memory with second-scale electron spin coherence times. Recently, quantum entanglement and teleportation have been shown between two nitrogen-vacancy memories, but scaling to larger networks requires more efficient spin-photon interfaces such as optical resonators. Here we report such nitrogen-vacancy-nanocavity systems in the strong Purcell regime with optical quality factors approaching 10,000 and electron spin coherence times exceeding 200 μs using a silicon hard-mask fabrication process. This spin-photon interface is integrated with on-chip microwave striplines for coherent spin control, providing an efficient quantum memory for quantum networks. PMID:25629223

  11. Integration of adaptive process control with computational simulation for spin-forming

    SciTech Connect

    Raboin, P. J., LLNL

    1998-03-10

    Improvements in spin-forming capabilities through upgrades to a metrology and machine control system and advances in numerical simulation techniques were studied in a two year project funded by Laboratory Directed Research and Development (LDRD) at Lawrence Livermore National Laboratory. Numerical analyses were benchmarked with spin-forming experiments and computational speeds increased sufficiently to now permit actual part forming simulations. Extensive modeling activities examined the simulation speeds and capabilities of several metal forming computer codes for modeling flat plate and cylindrical spin-forming geometries. Shape memory research created the first numerical model to describe this highly unusual deformation behavior in Uranium alloys. A spin-forming metrology assessment led to sensor and data acquisition improvements that will facilitate future process accuracy enhancements, such as a metrology frame. Finally, software improvements (SmartCAM) to the manufacturing process numerically integrate the part models to the spin-forming process and to computational simulations.

  12. Exploiting bistable pinning of a ferromagnetic vortex for nitrogen-vacancy spin control

    NASA Astrophysics Data System (ADS)

    Badea, R.; Wolf, M. S.; Berezovsky, J.

    2016-09-01

    The strong, localized magnetic field produced by the core of a ferromagnetic vortex provides a platform for addressing and controlling individual nitrogen-vacancy (NV) center spins in diamond. Translation of a vortex state in a thin ferromagnetic disk or wire can be understood as motion through an effective pinning potential, arising from the defects in the material. Coupling an NV spin to a vortex state in a proximal ferromagnet imprints the pinning landscape onto the spin transitions. Quantitative characterization of the pinning potential is necessary to control the spin-vortex system. First, we map the effective pinning potential by raster scanning the vortex core through a permalloy disk and measuring the hysteretic vortex displacement vs. magnetic field using differential magneto-optical microscopy. Second, we demonstrate that the interaction between the vortex and a nearby NV spin can be characterized using the pinning map and the path taken by the vortex core through the landscape. Finally, we identify locations of bistability in the pinning landscape, and use them to manipulate the nitrogen vacancy spin in a controlled bimodal fashion by switching the spin on and off resonance with a driving field on a ˜ 10 ns timescale at room temperature.

  13. Spin filter and spin valve in ferromagnetic graphene

    NASA Astrophysics Data System (ADS)

    Song, Yu; Dai, Gang

    2015-06-01

    We propose and demonstrate that a EuO-induced and top-gated graphene ferromagnetic junction can be simultaneously operated as a spin filter and a spin valve. We attribute such a remarkable result to a coexistence of a half-metal band and a common energy gap for opposite spins in ferromagnetic graphene. We show that both the spin filter and the spin valve can be effectively controlled by a back gate voltage, and they survive for practical metal contacts and finite temperature. Specifically, larger single spin currents and on-state currents can be reached with contacts with work functions similar to graphene, and the spin filter can operate at higher temperature than the spin valve.

  14. Control of vibrational states by spin-polarized transport in a carbon nanotube resonator

    NASA Astrophysics Data System (ADS)

    Stadler, P.; Belzig, W.; Rastelli, G.

    2015-02-01

    We study spin-dependent transport in a suspended carbon nanotube quantum dot in contact with two ferromagnetic leads and with the dot's spin coupled to the flexural mechanical modes. The spin-vibration interaction induces spin-flip processes between the two energy levels of the dot. This interaction arises from the spin-orbit coupling or a magnetic field gradient. The inelastic vibration-assisted spin flips give rise to a mechanical damping and, for an applied bias voltage, to a steady nonequilibrium occupation of the harmonic oscillator. We analyze these effects as function of the energy-level separation of the dot and the magnetic polarization of the leads. Depending on the magnetic configuration and the bias-voltage polarity, we can strongly cool a single mode or pump energy into it. In the latter case, we find that within our approximation, the system approaches eventually a regime of mechanical instability. Furthermore, owing to the sensitivity of the electron transport to the spin orientation, we find signatures of the nanomechanical motion in the current-voltage characteristic. Hence, the vibrational state can be read out in transport measurements.

  15. Indistinguishable tunable single photons emitted by spin-flip Raman transitions in InGaAs quantum dots.

    PubMed

    He, Yu; He, Yu-Ming; Wei, Y-J; Jiang, X; Chen, M-C; Xiong, F-L; Zhao, Y; Schneider, Christian; Kamp, Martin; Höfling, Sven; Lu, Chao-Yang; Pan, Jian-Wei

    2013-12-01

    This Letter reports all-optically tunable and highly indistinguishable single Raman photons from a driven single quantum dot spin. The frequency, linewidth, and lifetime of the Raman photons are tunable by varying the driving field power and detuning. Under continuous-wave excitation, subnatural linewidth single photons from off-resonant Raman scattering show an indistinguishability of 0.98(3). Under π pulse excitation, spin- and time-tagged Raman fluorescence photons show an almost vanishing multiphoton emission probability of 0.01(2) and a two-photon quantum interference visibility of 0.95(3). Lastly, Hong-Ou-Mandel interference is demonstrated between two single photons emitted from remote, independent quantum dots with an unprecedented visibility of 0.87(4). PMID:24476302

  16. Quantum Monte-Carlo simulation of spin-one antiferromagnets with single-ion anisotropy

    NASA Astrophysics Data System (ADS)

    Kato, Yasuyuki; Wierschem, Keola; Nishida, Yusuke; Batista, Cristian; Sengupta, Pinaki

    2013-03-01

    We study a spin-one Heisenberg model with uniaxial single-ion anisotropy, D, and Zeeman coupling to a magnetic field, B, parallel to the symmetry axis. We compute the (D / J , B / J) quantum phase diagram for square and simple cubic lattices by combining analytical and Quantum Monte Carlo approaches, and find a transition between XY-antiferromagnetic and ferronematic phases that spontaneously break the U(1) symmetry of the model. In the language of bosonic gases, this is a transition between a Bose-Einstein condensate (BEC) of single bosons and a BEC of pairs. For the efficient simulation of ferronematic phase, we developed and implemented a new multi-discontinuity algorithm based on the directed-loop algorithm. The ordinary quantum Monte-Carlo methods fall into freezing problems when we apply them to this system at large D / J and finite B / J ~ 1 . The new method does not suffer from the freezing problems. This research used resources of the NERSCC (DOE Contract No. DE-AC02-05CH11231). Work at LANL was performed under the auspices of a J. Robert Oppenheimer Fellowship and the U.S. DOE contract No. DE-AC52-06NA25396 through the LDRD program.

  17. Nanofabrication of spin-transfer torque devices by a polymethylmethacrylate mask one step process: Giant magnetoresistance versus single layer devices

    NASA Astrophysics Data System (ADS)

    Parge, Anne; Niermann, Tore; Seibt, Michael; Münzenberg, Markus

    2007-05-01

    We present a method to prepare magnetic spin torque devices of low specific resistance in a one step lithography process. The quality of the pillar devices is demonstrated for a standard magnetic double layer device. For single layer devices, we found hysteretic switching and a more complex dynamical excitation pattern in higher fields. A simple model to explain the resistance spikes is presented.

  18. Next-to-Leading Order Calculation of the Single Transverse Spin Asymmetry in the Drell-Yan Process

    SciTech Connect

    Vogelsang, Werner; Yuan, Feng

    2009-03-30

    We calculate the next-to-leading order perturbative QCD corrections to the transverse momentum weighted single transverse spin asymmetry in Drell-Yan lepton pair production in hadronic collisions. We identify the splitting function relevant for the scale evolution of the twist-three quark-gluon correlation function. We comment on the consequences of our results for phenomenology.

  19. Method for evaluating gravity effects in the testing of nutation dampers. [on single or dual spin satellites

    NASA Technical Reports Server (NTRS)

    Alfriend, K. T.

    1975-01-01

    A method is developed for determining the effect of gravity in the testing of nutation dampers on symmetric single or dual spin satellites. The basic theory is developed and then applied to the partially filled viscous ring damper and the spring-mass-dashpot damper. A comparison with test results for the viscous ring damper is also given.-

  20. Electronic Structure and Spin Configuration Trends of Single Transition Metal Impurity in Phase Change Material

    NASA Astrophysics Data System (ADS)

    Li, H.; Pei, J.; Shi, L. P.

    2016-10-01

    Fe doped phase change material GexSbyTez has shown experimentally the ability to alter its magnetic properties by phase change. This engineered spin degree of freedom into the phase change material offers the possibility of logic devices or spintronic devices where they may enable fast manipulation of ferromagnetism by a phase change mechanism. The electronic structures and spin configurations of isolated transition metal dopant in phase change material (iTM-PCM) is important to understand the interaction between localized metal d states and the unique delocalized host states of phase change material. Identifying an impurity center that has, in isolation, a nonvanishing magnetic moment is the first step to study the collective magnetic ordering, which originates from the interaction among close enough individual impurities. Theoretical description of iTM-PCM is challenging. In this work, we use a screened exchange hybrid functional to study the single 3d transition metal impurity in crystalline GeTe and GeSb2Te4. By curing the problem of local density functional (LDA) such as over-delocalization of the 3d states, we find that Fe on the Ge/Sb site has its majority d states fully occupied while its minority d states are empty, which is different from the previously predicted electronic configuration by LDA. From early transition metal Cr to heavier Ni, the majority 3d states are gradually populated until fully occupied and then the minority 3d states begin to be filled. Interpretive orbital interaction pictures are presented for understanding the local and total magnetic moments.

  1. Electronic Structure and Spin Configuration Trends of Single Transition Metal Impurity in Phase Change Material

    NASA Astrophysics Data System (ADS)

    Li, H.; Pei, J.; Shi, L. P.

    2016-06-01

    Fe doped phase change material GexSbyTez has shown experimentally the ability to alter its magnetic properties by phase change. This engineered spin degree of freedom into the phase change material offers the possibility of logic devices or spintronic devices where they may enable fast manipulation of ferromagnetism by a phase change mechanism. The electronic structures and spin configurations of isolated transition metal dopant in phase change material (iTM-PCM) is important to understand the interaction between localized metal d states and the unique delocalized host states of phase change material. Identifying an impurity center that has, in isolation, a nonvanishing magnetic moment is the first step to study the collective magnetic ordering, which originates from the interaction among close enough individual impurities. Theoretical description of iTM-PCM is challenging. In this work, we use a screened exchange hybrid functional to study the single 3d transition metal impurity in crystalline GeTe and GeSb2Te4. By curing the problem of local density functional (LDA) such as over-delocalization of the 3d states, we find that Fe on the Ge/Sb site has its majority d states fully occupied while its minority d states are empty, which is different from the previously predicted electronic configuration by LDA. From early transition metal Cr to heavier Ni, the majority 3d states are gradually populated until fully occupied and then the minority 3d states begin to be filled. Interpretive orbital interaction pictures are presented for understanding the local and total magnetic moments.

  2. Electric field control of spin-resolved edge states in graphene quantum nanorings

    SciTech Connect

    Farghadan, R.; Saffarzadeh, A.

    2014-05-07

    The electric-field effect on the electronic and magnetic properties of triangular and hexagonal graphene quantum rings with zigzag edge termination is investigated by means of the single-band tight-binding Hamiltonian and the mean-field Hubbard model. It is shown how the electron and spin states in the nanoring structures can be manipulated by applying an electric field. We find different spin-depolarization behaviors with variation of electric field strength due to the dependence of spin densities on the shapes and edges of this kind of nanorings. In the case of triangular quantum rings, the magnetization on the inner and outer edges can be selectively tuned and the spin states depolarize gradually as the field strength is increased, while in the case of hexagonal nanorings, the transverse electric field reduces the magnetic moments on both inner and outer edges symmetrically and rapidly.

  3. Discovery of room-temperature spin-glass behaviors in two-dimensional oriented attached single crystals

    NASA Astrophysics Data System (ADS)

    Ma, Ji; Chen, Kezheng

    2016-05-01

    In this study, room-temperature spin-glass behaviors were observed in flake-like oriented attached hematite (α-Fe2O3) and iron phosphate hydroxide hydrate (Fe5(PO4)4(OH)3·2H2O) single crystals. Remarkably, their coercivity (HC) values were found to be almost invariable at various given temperatures from 5 to 300 K. The spin topographic map in these flakes was assumed as superparamagnetic (SPM) "islands" isolated by spin glass (SG)-like "bridges". A spin-glass model was then proposed to demonstrate the spin frustration within these "bridges", which were formed by the staggered atomic planes in the uneven surfaces belonging to different attached nanoparticles. Under the spatial limitation and coupling shield of these "bridges", the SPM "islands" were found to be collectively frozen to form a superspin glass (SSG) state below 80 K in weak applied magnetic fields; whereas, when strong magnetic fields were applied, the magnetic coupling of these "islands" would become superferromagnetic (SFM) through tunneling superexchange, so that, these SFM spins could antiferromagnetically couple with the SG-like "bridges" to yield pronounced exchange bias (EB) effect.

  4. High-spin Fe2+ and Fe3+ in single-crystal aluminous bridgmanite in the lower mantle

    NASA Astrophysics Data System (ADS)

    Lin, Jung-Fu; Mao, Zhu; Yang, Jing; Liu, Jin; Xiao, Yuming; Chow, Paul; Okuchi, Takuo

    2016-07-01

    Spin and valence states of iron in single-crystal bridgmanite (Mg0.89Fe0.12Al0.11Si0.89O3) are investigated using X-ray emission and Mössbauer spectroscopies with laser annealing up to 115 GPa. The results show that Fe predominantly substitutes for Mg2+ in the pseudo-dodecahedral A site, in which 80% of the iron is Fe3+ that enters the lattice via the charge-coupled substitution with Al3+ in the octahedral B site. The total spin momentum and hyperfine parameters indicate that these ions remain in the high-spin state with Fe2+ having extremely high quadrupole splitting due to lattice distortion. (Al,Fe)-bearing bridgmanite is expected to contain mostly high-spin, A-site Fe3+, together with a smaller amount of A-site Fe2+, that remains stable throughout the region. Even though the spin transition of B-site Fe3+ in bridgmanite was reported to cause changes in its elasticity at high pressures, (Fe,Al)-bearing bridgmanite with predominantly A-site Fe will not exhibit elastic anomalies associated with the spin transition.

  5. Construction of Giant-Spin Hamiltonians from Many-Spin Hamiltonians by Third-Order Perturbation Theory and Application to an Fe3 Cr Single-Molecule Magnet.

    PubMed

    Tabrizi, Shadan Ghassemi; Arbuznikov, Alexei V; Kaupp, Martin

    2016-05-10

    A general giant-spin Hamiltonian (GSH) describing an effective spin multiplet of an exchange-coupled metal cluster with dominant Heisenberg interactions was derived from a many-spin Hamiltonian (MSH) by treating anisotropic interactions at the third order of perturbation theory. Going beyond the existing second-order perturbation treatment allows irreducible tensor operators of rank six (or corresponding Stevens operator equivalents) in the GSH to be obtained. Such terms were found to be of crucial importance for the fitting of high-field EPR spectra of a number of single-molecule magnets (SMMs). Also, recent magnetization measurements on trigonal and tetragonal SMMs have found the inclusion of such high-rank axial and transverse terms to be necessary to account for experimental data in terms of giant-spin models. While mixing of spin multiplets by local zero-field splitting interactions was identified as the major origin of these contributions to the GSH, a direct and efficient microscopic explanation had been lacking. The third-order approach developed in this work is used to illustrate the mapping of an MSH onto a GSH for an S=6 trigonal Fe3 Cr complex that was recently investigated by high-field EPR spectroscopy. Comparisons between MSH and GSH consider the simulation of EPR data with both Hamiltonians, as well as locations of diabolical points (conical intersections) in magnetic-field space. The results question the ability of present high-field EPR techniques to determine high-rank zero-field splitting terms uniquely, and lead to a revision of the experimental GSH parameters of the Fe3 Cr SMM. Indeed, a bidirectional mapping between MSH and GSH effectively constrains the number of free parameters in the GSH. This notion may in the future facilitate spectral fitting for highly symmetric SMMs. PMID:27062248

  6. Construction of Giant-Spin Hamiltonians from Many-Spin Hamiltonians by Third-Order Perturbation Theory and Application to an Fe3 Cr Single-Molecule Magnet.

    PubMed

    Tabrizi, Shadan Ghassemi; Arbuznikov, Alexei V; Kaupp, Martin

    2016-05-10

    A general giant-spin Hamiltonian (GSH) describing an effective spin multiplet of an exchange-coupled metal cluster with dominant Heisenberg interactions was derived from a many-spin Hamiltonian (MSH) by treating anisotropic interactions at the third order of perturbation theory. Going beyond the existing second-order perturbation treatment allows irreducible tensor operators of rank six (or corresponding Stevens operator equivalents) in the GSH to be obtained. Such terms were found to be of crucial importance for the fitting of high-field EPR spectra of a number of single-molecule magnets (SMMs). Also, recent magnetization measurements on trigonal and tetragonal SMMs have found the inclusion of such high-rank axial and transverse terms to be necessary to account for experimental data in terms of giant-spin models. While mixing of spin multiplets by local zero-field splitting interactions was identified as the major origin of these contributions to the GSH, a direct and efficient microscopic explanation had been lacking. The third-order approach developed in this work is used to illustrate the mapping of an MSH onto a GSH for an S=6 trigonal Fe3 Cr complex that was recently investigated by high-field EPR spectroscopy. Comparisons between MSH and GSH consider the simulation of EPR data with both Hamiltonians, as well as locations of diabolical points (conical intersections) in magnetic-field space. The results question the ability of present high-field EPR techniques to determine high-rank zero-field splitting terms uniquely, and lead to a revision of the experimental GSH parameters of the Fe3 Cr SMM. Indeed, a bidirectional mapping between MSH and GSH effectively constrains the number of free parameters in the GSH. This notion may in the future facilitate spectral fitting for highly symmetric SMMs.

  7. Transverse Spin Structure of the Nucleon through Target Single Spin Asymmetry in Semi-Inclusive Deep-Inelastic $(e,e^\\prime \\pi^\\pm)$ Reaction at Jefferson Lab

    SciTech Connect

    Gao, H; Chen, J -P; Qian, X; Qiang, Y; Huang, M; Afanasev, A; Anselmino, M; Avakian, H; Cates, G; Chudakov, E; Cisbani, E; de Jager, C; Garibaldi, F; Hu, B T; Jiang, X; Kumar, K S; Li, X M; Lu, H J; Meziani, Z -E; Ma, B -Q; Mao, Y J; Peng, J -C; Prokudin, A; Schlegel, M; Souder, P; Xiao, Z G; Ye, Y; Zhu, L

    2011-01-01

    Jefferson Lab (JLab) 12 GeV energy upgrade provides a golden opportunity to perform precision studies of the transverse spin and transverse-momentum-dependent structure in the valence quark region for both the proton and the neutron. In this paper, we focus our discussion on a recently approved experiment on the neutron as an example of the precision studies planned at JLab. The new experiment will perform precision measurements of target Single Spin Asymmetries (SSA) from semi-inclusive electro-production of charged pions from a 40-cm long transversely polarized $^3$He target in Deep-Inelastic-Scattering kinematics using 11 and 8.8 GeV electron beams. This new coincidence experiment in Hall A will employ a newly proposed solenoid spectrometer (SoLID). The large acceptance spectrometer and the high polarized luminosity will provide precise 4-D ($x$, $z$, $P_T$ and $Q^2$) data on the Collins, Sivers, and pretzelocity asymmetries for the neutron through the azimuthal angular dependence. The full 2$\\pi$ azimuthal angular coverage in the lab is essential in controlling the systematic uncertainties. The results from this experiment, when combined with the proton Collins asymmetry measurement and the Collins fragmentation function determined from the e$^+$e$^-$ collision data, will allow for a quark flavor separation in order to achieve a determination of the tensor charge of the d quark to a 10% accuracy. The extracted Sivers and pretzelocity asymmetries will provide important information to understand the correlations between the quark orbital angular momentum and the nucleon spin and between the quark spin and nucleon spin.

  8. Generation of an external magnetic field with the spin orientation effect in a single layer Ising nanographene

    NASA Astrophysics Data System (ADS)

    Şarlı, Numan

    2016-09-01

    In this work, the magnetic properties of the single layer Ising nanogaphene (SLING) are investigated by using Kaneyoshi approach (KA) within the effective field theory for different spin orientations of its magnetic atoms. We find that the magnetizations of the SLING has no phase transition, certain Curie temperature and distinct peak of susceptibility at Tc for the some spin orientations at the zero external magnetic field (H=0.0). Because these behaviors occur at H≠0.0, we suggest that the SLING generates an external magnetic field and behaves as an external magnetic field generator for these spin orientations. However, the SLING exhibits ferromagnetic behaviors for only one spin orientations. But, it exhibits antiferromagnetic behaviors for the others. For the AFM cases, diamagnetic susceptibility behaviors and type II superconductivity hysteresis behaviors are obtained. We hope that these results can open a door to obtain new class of single layer graphene and graphene-based magnetic field generator devices with the spin orientation effect.

  9. Spin Hall Control of Magnetization in a Perpendicularly-Magnetized Magnetic Insulator

    NASA Astrophysics Data System (ADS)

    Pai, Chi-Feng; Quindeau, Andy; Tang, Astera; Onbasli, Mehmet; Mann, Maxwell; Caretta, Lucas; Ross, Caroline; Beach, Geoffrey

    Spin Hall effect (SHE)-induced spin-orbit torque (SOT) has been shown to be an efficient mechanism to control the magnetization in magnetic heterostructures. Although numerous works have demonstrated the efficacy of SOT in manipulating the magnetization of ferromagnetic metals (FM), SOT-controlled switching of ferromagnetic insulators (FMIs) has not yet been observed. In this work we show that spin Hall currents in Pt and Ta can generate SOTs strong enough to control the magnetization direction in an adjacent thulium iron garnet FMI film with perpendicular magnetic anisotropy. We find that dc current in the heavy metal (HM) generates an out-of-plane effective field in the FMI consistent with an antidamping torque whose magnitude is comparable to that observed in all-metallic systems. Spin Hall magnetoresistance (SMR) measurements reveal a large spin-mixing conductance, which implies considerable spin transparency at the metal/insulator interface and explains the observed strong current-induced torque. Our results show that charge currents flowing in a HM can be used to both control and detect the magnetization direction in a FMI electrically.

  10. Voltage-controlled spin selection in a magnetic resonant tunneling diode.

    PubMed

    Slobodskyy, A; Gould, C; Slobodskyy, T; Becker, C R; Schmidt, G; Molenkamp, L W

    2003-06-20

    We have fabricated all II-VI semiconductor resonant tunneling diodes based on the (Zn,Mn,Be)Se material system, containing dilute magnetic material in the quantum well, and studied their current-voltage characteristics. When subjected to an external magnetic field the resulting spin splitting of the levels in the quantum well leads to a splitting of the transmission resonance into two separate peaks. This is interpreted as evidence of tunneling transport through spin polarized levels, and could be the first step towards a voltage controlled spin filter.

  11. Voltage-controlled spin selection in a magnetic resonant tunneling diode.

    PubMed

    Slobodskyy, A; Gould, C; Slobodskyy, T; Becker, C R; Schmidt, G; Molenkamp, L W

    2003-06-20

    We have fabricated all II-VI semiconductor resonant tunneling diodes based on the (Zn,Mn,Be)Se material system, containing dilute magnetic material in the quantum well, and studied their current-voltage characteristics. When subjected to an external magnetic field the resulting spin splitting of the levels in the quantum well leads to a splitting of the transmission resonance into two separate peaks. This is interpreted as evidence of tunneling transport through spin polarized levels, and could be the first step towards a voltage controlled spin filter. PMID:12857209

  12. Efficient and accurate local single reference correlation methods for high-spin open-shell molecules using pair natural orbitals

    NASA Astrophysics Data System (ADS)

    Hansen, Andreas; Liakos, Dimitrios G.; Neese, Frank

    2011-12-01

    A production level implementation of the high-spin open-shell (spin unrestricted) single reference coupled pair, quadratic configuration interaction and coupled cluster methods with up to doubly excited determinants in the framework of the local pair natural orbital (LPNO) concept is reported. This work is an extension of the closed-shell LPNO methods developed earlier [F. Neese, F. Wennmohs, and A. Hansen, J. Chem. Phys. 130, 114108 (2009), 10.1063/1.3086717; F. Neese, A. Hansen, and D. G. Liakos, J. Chem. Phys. 131, 064103 (2009), 10.1063/1.3173827]. The internal space is spanned by localized orbitals, while the external space for each electron pair is represented by a truncated PNO expansion. The laborious integral transformation associated with the large number of PNOs becomes feasible through the extensive use of density fitting (resolution of the identity (RI)) techniques. Technical complications arising for the open-shell case and the use of quasi-restricted orbitals for the construction of the reference determinant are discussed in detail. As in the closed-shell case, only three cutoff parameters control the average number of PNOs per electron pair, the size of the significant pair list, and the number of contributing auxiliary basis functions per PNO. The chosen threshold default values ensure robustness and the results of the parent canonical methods are reproduced to high accuracy. Comprehensive numerical tests on absolute and relative energies as well as timings consistently show that the outstanding performance of the LPNO methods carries over to the open-shell case with minor modifications. Finally, hyperfine couplings calculated with the variational LPNO-CEPA/1 method, for which a well-defined expectation value type density exists, indicate the great potential of the LPNO approach for the efficient calculation of molecular properties.

  13. Control-system techniques for improved departure/spin resistance for fighter aircraft

    NASA Technical Reports Server (NTRS)

    Nguyen, L. T.; Gilbert, W. P.; Ogburn, M. E.

    1980-01-01

    Some fundamental information on control system effects on controllability of highly maneuverable aircraft at high angles of attack are summarized as well as techniques for enhancing fighter aircraft departure/spin resistance using control system design. The discussion includes: (1) a brief review of pertinent high angle of attack phenomena including aerodynamics, inertia coupling, and kinematic coupling; (2) effects of conventional stability augmentation systems at high angles of attack; (3) high angle of attack control system concepts designed to enhance departure/spin resistance; and (4) the outlook for applications of these concepts to future fighters, particularly those designs which incorporate relaxed static stability.

  14. Most spin-1/2 transition-metal ions do have single ion anisotropy

    SciTech Connect

    Liu, Jia; Whangbo, Myung-Hwan E-mail: mike-whangbo@ncsu.edu; Koo, Hyun-Joo; Xiang, Hongjun E-mail: mike-whangbo@ncsu.edu; Kremer, Reinhard K.

    2014-09-28

    The cause for the preferred spin orientation in magnetic systems containing spin-1/2 transition-metal ions was explored by studying the origin of the easy-plane anisotropy of the spin-1/2 Cu{sup 2+} ions in CuCl{sub 2}·2H{sub 2}O, LiCuVO{sub 4}, CuCl{sub 2}, and CuBr{sub 2} on the basis of density functional theory and magnetic dipole-dipole energy calculations as well as a perturbation theory treatment of the spin-orbit coupling. We find that the spin orientation observed for these spin-1/2 ions is not caused by their anisotropic spin exchange interactions, nor by their magnetic dipole-dipole interactions, but by the spin-orbit coupling associated with their crystal-field split d-states. Our study also predicts in-plane anisotropy for the Cu{sup 2+} ions of Bi{sub 2}CuO{sub 4} and Li{sub 2}CuO{sub 2}. The results of our investigations dispel the mistaken belief that magnetic systems with spin-1/2 ions have no magnetic anisotropy induced by spin-orbit coupling.

  15. Multifunctional resistive-heating and color-changing monofilaments produced by a single-step coaxial melt-spinning process.

    PubMed

    Laforgue, Alexis; Rouget, Geoffroy; Dubost, Sylvain; Champagne, Michel F; Robitaille, Lucie

    2012-06-27

    Multifunctional coaxial monofilaments were successfully produced by melt-spinning several polymer composites in a single-step. The external layer of the monofilaments was a thermochromic composite having a color-transition at 40 °C (above the ambient temperature) in order to avoid control interferences by the external temperature. The core layer of the monofilaments was a conductive polymer nanocomposite whose resistive heating properties were used to control the monofilament's temperature and therefore its color using electrical current. The careful selection of the materials and adequate formulation allowed to obtain a trilayer structure with enhanced compatibility between the layers. The mechanical properties of the monofilaments were improved by a solid-state stretching step while also decreasing their diameter. A 64 cm(2) prototype fabric was woven to characterize the resistive-heating and color-changing properties of the monofilaments. Exceptional thermal output levels were reached, with a temperature rising up to over 100 °C at voltages above 110 V. The reversible color change properties were also successfully demonstrated.

  16. Demonstration of a Coherent Electronic Spin Cluster in Diamond.

    PubMed

    Knowles, Helena S; Kara, Dhiren M; Atatüre, Mete

    2016-09-01

    An obstacle for spin-based quantum sensors is magnetic noise due to proximal spins. However, a cluster of such spins can become an asset, if it can be controlled. Here, we polarize and readout a cluster of three nitrogen electron spins coupled to a single nitrogen-vacancy spin in diamond. We further achieve sub-nm localization of the cluster spins. Finally, we demonstrate coherent spin exchange between the species by simultaneous dressing of the nitrogen-vacancy and the nitrogen states. These results establish the feasibility of environment-assisted sensing and quantum simulations with diamond spins. PMID:27636464

  17. Demonstration of a Coherent Electronic Spin Cluster in Diamond

    NASA Astrophysics Data System (ADS)

    Knowles, Helena S.; Kara, Dhiren M.; Atatüre, Mete

    2016-09-01

    An obstacle for spin-based quantum sensors is magnetic noise due to proximal spins. However, a cluster of such spins can become an asset, if it can be controlled. Here, we polarize and readout a cluster of three nitrogen electron spins coupled to a single nitrogen-vacancy spin in diamond. We further achieve sub-nm localization of the cluster spins. Finally, we demonstrate coherent spin exchange between the species by simultaneous dressing of the nitrogen-vacancy and the nitrogen states. These results establish the feasibility of environment-assisted sensing and quantum simulations with diamond spins.

  18. Demonstration of a Coherent Electronic Spin Cluster in Diamond.

    PubMed

    Knowles, Helena S; Kara, Dhiren M; Atatüre, Mete

    2016-09-01

    An obstacle for spin-based quantum sensors is magnetic noise due to proximal spins. However, a cluster of such spins can become an asset, if it can be controlled. Here, we polarize and readout a cluster of three nitrogen electron spins coupled to a single nitrogen-vacancy spin in diamond. We further achieve sub-nm localization of the cluster spins. Finally, we demonstrate coherent spin exchange between the species by simultaneous dressing of the nitrogen-vacancy and the nitrogen states. These results establish the feasibility of environment-assisted sensing and quantum simulations with diamond spins.

  19. How to control spin-Seebeck current in a metal-quantum dot-magnetic insulator junction

    NASA Astrophysics Data System (ADS)

    Gu, Lei; Fu, Hua-Hua; Wu, Ruqian

    2016-09-01

    The control of the spin-Seebeck current is still a challenging task for the development of spin caloritronic devices. Here, we construct a spin-Seebeck device by inserting a quantum dot (QD) between the metal lead and magnetic insulator. Using the slave-particle approach and noncrossing approximation, we find that the spin-Seebeck effect increases significantly when the energy level of the QD locates near the Fermi level of the metal lead due to the enhancement of spin flipping and occurrences of quantum resonance. Since this can be easily realized by applying a gate voltage in experiments, the spin-Seebeck device proposed here can also work as a thermovoltaic transistor. Moreover, the optimal correlation strength and the energy level position of the QD are discussed to maximize the spin-Seebeck current as required for applications in controllable spin caloritronic devices.

  20. High-Fidelity Single-Qubit Gates for Two-Electron Spin Qubits

    NASA Astrophysics Data System (ADS)

    Botzem, Tim; Cerfontaine, Pascal; Divincenzo, David P.; Bluhm, Hendrik

    2014-03-01

    High fidelity gate operations for manipulating individual and multiple qubits in the presence of decoherence are a prerequisite for fault-tolerant quantum information processing. However, the control methods used in earlier experiments on semiconductor two-electron spin qubits are based on unrealistic approximations which preclude reaching the required fidelities. An attractive remedy is to use control pulses found in numerical simulations that minimize the infidelity from decoherence and take the experimentally important imperfections and constraints into account. Using this approach and experimentally determined noise spectra, we find pulses for singlet-triplet qubits in GaAs double quantum dots with fidelities as high as 99.9%. Fully eliminating systematic pulse errors will likely require a calibration of the pulses on the experiment using some form of self-consistent approach. Starting with inaccurate control pulses we show that elimination of individual systematic gate errors is possible by applying a modification of the bootstrap protocol proposed by Dobrovitski et al. (PRL 105, 2010) while still retaining the pulses' high fidelities.

  1. Single shot spin readout with a cryogenic high-electron-mobility transistor amplifier at sub-Kelvin temperatures

    DOE PAGES

    Tracy, Lisa A.; Luhman, Dwight R.; Carr, Stephen M.; Bishop, Nathaniel C.; Ten Eyck, Gregory A.; Pluym, Tammy; Wendt, Joel R.; Lilly, Michael P.; Carroll, Malcolm S.

    2016-02-08

    We use a cryogenic high-electron-mobility transistor circuit to amplify the current from a single electron transistor, allowing for demonstration of single shot readout of an electron spin on a single P donor in Si with 100 kHz bandwidth and a signal to noise ratio of ~9. In order to reduce the impact of cable capacitance, the amplifier is located adjacent to the Si sample, at the mixing chamber stage of a dilution refrigerator. For a current gain of ~2.7 x 103 the power dissipation of the amplifier is 13 μW, the bandwidth is ~1.3 MHz, and for frequencies above 300more » kHz the current noise referred to input is ≤ 70 fA/√Hz. Furthermore, with this amplification scheme, we are able to observe coherent oscillations of a P donor electron spin in isotopically enriched 28Si with 96% visibility.« less

  2. Controlled transport of superparamagnetic beads with spin-valves

    NASA Astrophysics Data System (ADS)

    Altman, Wendy R.; Moreland, John; Russek, Stephen E.; Han, Bruce W.; Bright, Victor M.

    2011-10-01

    Trapping, release, and transport of individual, or ensembles of, 2.8 μm superparamagnetic beads (SPB) functionalized with streptavidin were demonstrated with an addressable array of spin-valve (SV) traps integrated into a microfluidic channel. The linear array consists of two staggered lines of 1 μm × 8 μm SVs toggled "on" or "off" with 10 ms and 150 mA or -100 mA current pulses, respectively. The SPB is trapped when the SV is "on" and released or ignored when the SV is "off". This "switchable permanent magnet" offers a low power alternative to other precision microfluidic transport devices.

  3. Electrically controlled spin polarization and selection in a topological insulator sandwiched between ferromagnetic electrodes

    SciTech Connect

    Guo, Junji; Liao, Wenhu Zhao, Heping; Zhou, Guanghui

    2014-01-14

    We theoretically investigate the electrically controllable spin polarization and selective efficiency of the edge state Dirac electron in a two-dimensional topological insulator (TI) sandwiched between ferromagnetic (FM) electrodes by using the method of Keldysh nonequilibrium Green's function. A nearly full spin polarization of the topological edge state with giant inversion of ∼80% is observed, which is much higher than the value previously reported. Moreover, the selective efficiency for spin-up electrons under the modulation of the parallel configuration of FM electrodes has been demonstrated to be larger than 95% for the first time, while that for spin-down electrons in the antiparallel case is higher than 90% in a wide energy range, owing to the inter-edge spin tunneling induced backscattering and spin dephasing effect. The obtained results may provide a deeper understanding of the TI edge states and a valuable guidance to design spin switch and filter with high on-off speed and selective efficiency based on TIs.

  4. Electrostatic control over polarized currents through the spin-orbital Kondo effect

    NASA Astrophysics Data System (ADS)

    Büsser, C. A.; Feiguin, A. E.; Martins, G. B.

    2012-06-01

    Numerical calculations indicate that by suitably controlling the individual gate voltages of a capacitively coupled parallel double quantum dot, with each quantum dot coupled to one of two independent nonmagnetic channels, this system can be set into a spin-orbital Kondo state by applying a magnetic field. This Kondo regime, closely related to the SU(4) Kondo, flips spin from 1 to 0 through cotunneling processes that generate almost totally spin-polarized currents with opposite spin orientation along the two channels. Moreover, by appropriately changing the gate voltages of both quantum dots, one can simultaneously flip the spin polarization of the currents in each channel. As a similar zero magnetic field Kondo effect has been recently observed by Okazaki [Phys. Rev. BPLRBAQ1098-012110.1103/PhysRevB.84.161305 84, 161305(R) (2011)], we analyze a range of magnetic field values where this polarization effect seems robust, suggesting that the setup may be used as an efficient bipolar spin filter, which can generate electrostatically reversible spatially separated spin currents with opposite polarizations.

  5. Investigation of electron relaxation in the metal proteins containing the single paramagnetic centers of integer spin by nuclear forward scattering of synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Popov, E. A.; Yanvarev, Eugene A.; Bashkirov, Sh. S.; Kouznetsov, V. I.

    2001-11-01

    Nuclear forward scattering (NFS) of synchrotron radiation (SR) is being modeled in metal proteins containing the single paramagnetic centers of integer spin (Fe2+). It is known the spin fluctuations in the electron environment of Moessbauer ion Fe2+ will be manifested itself in NFS if a sample undergoes the influence of applied magnetic field of a few Tesla. Under the condition we are analyzing how the resonant response (RR) of a sample to SR pulse will be changed due to the both spin-lattice and spin-spin interactions.

  6. Gyroscope spin axis direction control for the Gravity Probe B satellite

    NASA Astrophysics Data System (ADS)

    Bencze, William Joseph

    The Gravity Probe B Relativity Experiment (GP-B) is a joint NASA/Stanford University orbiting astrophysics experiment, under development, to test two predictions of Einstein's theory of general relativity, the geodetic and frame-dragging effects, using orbiting, ultra-precise, mechanical, electrically-suspended gyroscopes (ESVG) carefully isolated from Newtonian torques. General relativity predicts that the gyroscopes' spin axes will precess with respect to a distant inertial reference frame at a rate of 6.6 arc-sec/year for the geodetic effect, and 42 marc-sec/year due to frame-dragging in the planned orbit. To achieve the needed levels of measurement precision, the gyroscopes' axes must be aligned to within 10 arc-sec of the line-of-sight to a distant guide star. Presented is a technique by which the initial orientation of each gyroscope can be controlled through the use of residual torques generated by the gyroscope' s electrostatic suspension system. The electrostatic torques acting on the gyroscope depend on the rotor shape, which is nominally spherical but also contains small manufacturing asphericities and a spin-induced bulge. These torques are averaged by rotor spin to take on a simple form: they cause the gyroscope to precess about the suspension electrode axes. Orientation control torques are applied by introducing additional suspension voltages to the electrodes in combinations which do not exert a force on the gyroscope, but do generate a torque. A control system was developed to use these torques to drive the spin axis to a desired orientation in minimum-time using a bang-bang actuation scheme. A net torque identification scheme was also created to monitor polhode-induced modulations of the spin-averaged torques. This information was used by the orientation control system to keep the spin axis on a minimum-time trajectory. Laboratory experiments confirmed the validity of the spin-averaged torque models and gave a proof-of-principle of the

  7. Observation of Ising spin-nematic order and its close relationship to the superconductivity in FeSe single crystals

    NASA Astrophysics Data System (ADS)

    Yuan, Dongna; Yuan, Jie; Huang, Yulong; Ni, Shunli; Feng, Zhongpei; Zhou, Huaxue; Mao, Yiyuan; Jin, Kui; Zhang, Guangming; Dong, Xiaoli; Zhou, Fang; Zhao, Zhongxian

    2016-08-01

    Superconducting FeSe single crystals of (001) orientation are synthesized via a hydrothermal ion-release route. An Ising spin-nematic order is identified by our systematic measurements of in-plane angular-dependent magnetoresistance (AMR) and static magnetization. The turn-on temperature of anisotropic AMR signifies the Ising spin-nematic ordering temperature Tsn, below which a twofold rotational symmetry is observed in the iron plane. A downward curvature appears below Tsn in the temperature dependence of static magnetization for the weak in-plane magnetic field as reported previously. Remarkably, we find a universal linear relationship between Tc and Tsn among various superconducting samples, indicating that the spin nematicity and the superconductivity in FeSe have a common microscopic origin.

  8. Entanglement entropy and fidelity susceptibility in the one-dimensional spin-1 XXZ chains with alternating single-site anisotropy.

    PubMed

    Ren, Jie; Liu, Guang-Hua; You, Wen-Long

    2015-03-18

    We study the fidelity susceptibility in an antiferromagnetic spin-1 XXZ chain numerically. By using the density-matrix renormalization group method, the effects of the alternating single-site anisotropy D on fidelity susceptibility are investigated. Its relation with the quantum phase transition is analyzed. It is found that the quantum phase transition from the Haldane spin liquid to periodic Néel spin solid can be well characterized by the fidelity. Finite size scaling of fidelity susceptibility shows a power-law divergence at criticality, which indicates the quantum phase transition is of second order. The results are confirmed by the second derivative of the ground-state energy. We also study the relationship between the entanglement entropy, the Schmidt gap and quantum phase transitions. Conclusions drawn from these quantum information observables agree well with each other. PMID:25707024

  9. Beam Normal Single Spin Asymmetry in the N-to-Delta Transition

    NASA Astrophysics Data System (ADS)

    Nuruzzaman, Nuruzzaman; Qweak Collaboration

    2013-10-01

    The Q-weak experiment in Hall C at the Thomas Jefferson National Accelerator Facility has made the first direct measurement of the weak charge of the proton, QWp,through the precision measurement of the parity-violating (PV) asymmetry in elastic e-p scattering at low momentum transfer. The data are currently under analysis. There is a parity conserving Beam Normal Single Spin Asymmetry or transverse asymmetry (An) on H2 with a sin(φ) -like dependence due to 2- γ exchange. The size of An is few ppm, so a few percent residual transverse polarization in the beam, in addition to potentially small broken azimuthal symmetries in the detector, might lead to few ppb corrections to the Q-weak data. As part of a program of An background studies, we made the first measurement of An in the N-to-Delta transition using the Q-weak apparatus. An from electron-nucleon scattering is also a unique tool to study the γ* ΔΔ form factors. Status of the analysis will be presented. Supported in part by the Department of Energy and the National Science Foundation

  10. Spin-lattice relaxation in p-type gallium arsenide single crystals

    NASA Astrophysics Data System (ADS)

    Zerrouati, K.; Fabre, F.; Bacquet, G.; Bandet, J.; Frandon, J.; Lampel, G.; Paget, D.

    1988-01-01

    An optical-pumping technique is used to measure the spin-relaxation time of photogenerated conduction electrons in several p-type GaAs single crystals doped with various amounts of acceptors in the 1.7-300 K temperature range. Our experimental results are compared with those of the literature and with the predictions of the existing theoretical calculations. From about 10 K, the Bir-Aronov-Pikus (BAP) mechanism is found to be relevant for moderately doped (1017-1018 cm-3), up to about 150 K, or degenerate (up to 300 K) semiconductors, using the electronic temperature, deduced from the luminescence spectra, rather than the sample temperature. The D'yakonov-Perel' (DP) process was found to be active above 200 K for moderately doped samples and from about 80 K to room temperature for samples doped in the (1.6-6)×1016-cm-3 acceptor-concentration range. Our original results obtained at liquid-helium temperatures at whatever the doping level cannot be explained either by the DP mechanism or by the BAP process.

  11. Helicity asymmetry E measurement for single pi^0 photoproduction with a frozen spin target

    SciTech Connect

    Hideko Iwamoto

    2012-04-01

    The helicity asymmetry for single neutral pion photoproduction was measured using the CLAS detector in Hall B at the Thomas Jefferson National Accelerator Facility. This measurement used longitudinally polarized protons and circularly polarized photons with photon energies between 0.35 GeV to 2.4 GeV. The target was a frozen-spin butanol (C{sub 4}H{sub 9}OH) target, polarized at about 85%. The helicity asymmetry E for the {gamma}p {yields} p{pi}{sup 0} was measured with missing-mass technique at the high statistics of about 12 x 10{sup 6} events. The experimental results are compared to three available theoretical predictions, SAID, MAID, and EBAC. The preliminary results are in good agreement with the model calculations at low E{sub {gamma}} energy bins. However, a significant deviation is observed at high energy bins. Therefore, the new data will help to constrain the parameters of the theoretical models.

  12. Electron Spin Resonance Analysis of the Nitroxide Spin Label 2,2,6,6-Tetramethylpiperidone-N-Oxyl (Tempone) in Single Crystals of the Reduced Tempone Matrix

    PubMed Central

    Snipes, Wallace; Cupp, James; Cohn, Gerald; Keith, Alec

    1974-01-01

    The nitroxide spin label Tempone (2,2,6,6-tetramethylpiperidone-N-oxyl) can be reduced with ascorbic acid to give a nonparamagnetic species. Single crystals of reduced Tempone serve as a suitable host matrix to orient trace quantities of Tempone for ESR analysis. In these crystals the majority of the Tempone molecules are well-oriented, but a smaller fraction of the molecules tumble freely to give an isotropic electron spin resonance (ESR) spectrum. ESR transitions for the oriented molecules are saturated at much lower microwave power levels than for the tumbling molecules. For the oriented molecules, an analysis of the anisotropy of the spectroscopic splitting factor (g) gives principal values of g1 = 2.0094, g2 = 2.0061, g3 = 2.0021. The hyperfine coupling tensor is nearly axially symmetric, with principal values (in gauss) of A1 = 6.5, A2 = 6.7, A3 = 33.0. Within experimental error, the principal axis systems for the g tensor and the hyperfine tensor are identical. Comparison of the average values of g and A with the isotropic values of these parameters for Tempone in solvents of different polarity suggests a method for choosing the most appropriate tensor elements to be used for spin label experiments in various solvent systems. PMID:4359744

  13. Cloning transformations in spin networks without external control

    SciTech Connect

    De Chiara, Gabriele; Fazio, Rosario; Montangero, Simone; Macchiavello, Chiara; Palma, G. Massimo

    2005-07-15

    In this paper we present an approach to quantum cloning with unmodulated spin networks. The cloner is realized by a proper design of the network and a choice of the coupling between the qubits. We show that in the case of phase covariant cloner the XY coupling gives the best results. In the 1{yields}2 cloning we find that the value for the fidelity of the optimal cloner is achieved, and values comparable to the optimal ones in the general N{yields}M case can be attained. If a suitable set of network symmetries are satisfied, the output fidelity of the clones does not depend on the specific choice of the graph. We show that spin network cloning is robust against the presence of static imperfections. Moreover, in the presence of noise, it outperforms the conventional approach. In this case the fidelity exceeds the corresponding value obtained by quantum gates even for a very small amount of noise. Furthermore, we show how to use this method to clone qutrits and qudits. By means of the Heisenberg coupling it is also possible to implement the universal cloner although in this case the fidelity is 10% off that of the optimal cloner.

  14. Controlling the spin of co atoms on pt(111) by hydrogen adsorption.

    PubMed

    Dubout, Q; Donati, F; Wäckerlin, C; Calleja, F; Etzkorn, M; Lehnert, A; Claude, L; Gambardella, P; Brune, H

    2015-03-13

    We investigate the effect of H adsorption on the magnetic properties of individual Co atoms on Pt(111) with scanning tunneling microscopy. For pristine Co atoms, we detect no inelastic features in the tunnel spectra. Conversely, CoH and CoH2 show a number of low-energy vibrational features in their differential conductance identified by isotope substitution. Only the fcc-adsorbed species present conductance steps of magnetic origin, with a field splitting identifying their effective spin as Seff=2 for CoH and 3/2 for CoH2. The exposure to H2 and desorption through tunnel electrons allow the reversible control of the spin in half-integer steps. Because of the presence of the surface, the hydrogen-induced spin increase is opposite to the spin sequence of CoHn molecules in the gas phase.

  15. Spin and charge modulations in a single-hole-doped Hubbard ladder: Verification with optical lattice experiments

    NASA Astrophysics Data System (ADS)

    Zhu, Zheng; Weng, Zheng-Yu; Ho, Tin-Lun

    2016-03-01

    We show that pronounced modulations in spin and charge densities can be induced by the insertion of a single hole in an otherwise half-filled two-leg Hubbard ladder. Accompanied with these modulations is a loosely bound structure of the doped charge with a spin-1/2, in contrast to the tightly bound case where such modulations are absent. These behaviors are caused by the interference of the Berry phases associated with a string of flipped spins (or "phase strings") left behind as a hole travels through a spin bath with a short-range antiferromagnetic order. The key role of the phase strings is also reflected in how the system responds to increasing spin polarization and the on-site repulsion, addition of a second hole, and increasing asymmetry between intra- and interchain hopping. Remarkably, all these properties persist down to ladders as short as ˜10 sites, as the smoking gun of the phase-string effect. They can therefore be studied in cold-atom experiments using the recently developed fermion microscope.

  16. Optimizing the spin sensitivity of grain boundary junction nanoSQUIDs—towards detection of small spin systems with single-spin resolution

    NASA Astrophysics Data System (ADS)

    Wölbing, R.; Schwarz, T.; Müller, B.; Nagel, J.; Kemmler, M.; Kleiner, R.; Koelle, D.

    2014-12-01

    We present an optimization study of the spin sensitivity of nano superconducting quantum interference devices (SQUIDs) based on resistively shunted grain boundary Josephson junctions. In addition the direct current SQUIDs contain a narrow constriction onto which a small magnetic particle can be placed (with its magnetic moment in the plane of the SQUID loop and perpendicular to the grain boundary) for efficient coupling of its stray magnetic field to the SQUID loop. The separation of the location of optimum coupling from the junctions allows for an independent optimization of the coupling factor {{φ }μ } and junction properties. We present different methods for calculating {{φ }μ } (for a magnetic nanoparticle placed 10 nm above the constriction) as a function of device geometry and show that those yield consistent results. Furthermore, by numerical simulations we obtain a general expression for the dependence of the SQUID inductance on geometrical parameters of our devices, which allows to estimate their impact on the spectral density of flux noise {{S}Φ } of the SQUIDs in the thermal white noise regime. Our analysis of the dependence of {{S}Φ } and {{φ }μ } on the geometric parameters of the SQUID layout yields a spin sensitivity Sμ 1/2=SΦ 1/2/{{φ }μ } of a few {{μ }B} H{{z}-1/2} ({{μ }B} is the Bohr magneton) for optimized parameters, respecting technological constraints. However, by comparison with experimentally realized devices we find significantly larger values for the measured white flux noise, as compared to our theoretical predictions. Still, a spin sensitivity on the order of 10 {{μ }B} H{{z}-1/2} for optimized devices seems to be realistic.

  17. Optical quantum memory made from single nuclear spin in nitrogen vacancy in diamond

    NASA Astrophysics Data System (ADS)

    Yang, Sen; Wang, Ya; Tran, Thai Hien; Momenzadeh, S. Ali; Stoehr, Rainer; Neumann, Philipp; Kosaka, Hideo; Wrachtrup, Joerg

    2015-03-01

    Quantum repeater is one of the key elements to realize long distance quantum communication. In the heart of a quantum repeater is quantum memory. There are a few requirements for this memory: it needs to couple to flying qubits: photon; it needs to have long coherence time, so quantum error correction algorithm can be performed in the quantum repeater nods; it needs to be stable under optical illuminations. Nitrogen nuclear spin is available for every nitrogen vacancy center(NV) in diamond. Besides it can be a robust quantum memory for spin qubit operations, nitrogen nuclear spin can couple to photon by taking advantage of optically resonant excitation of spin-selective transitions in low temperature. Here we demonstrate the coherent storage of quantum information from photon into nuclear spin. We show this quantum memory fulfils requirements as quantum memory for quantum repeater. Coherent time beyond 5 seconds is measured in 13 C natural abundant sample. Under resonant laser excitations, the excited state quadruple and hyperfine interaction could lead to decoherence of nuclear spin. We show those interactions are low and nuclear spin can keep its coherence over 1000 times resonant laser excitation of electron spin.

  18. Spinning Reserves from Controllable Packaged Through the Wall Air Conditioner (PTAC) Units

    SciTech Connect

    Kirby, B.J.

    2003-04-02

    This report summarizes the feasibility of providing spinning reserves from packaged through the wall air conditioning (PTAC) units. Spinning reserves, together with non-spinning reserves, compose the contingency reserves; the essential resources that the power system operator uses to restore the generation and load balance and maintain bulk power system reliability in the event of a major generation or transmission outage. Spinning reserves are the fastest responding and most expensive reserves. Many responsive load technologies could (and we hope will) be used to provide spinning reserve. It is also easier for many loads (including air conditioning loads) to provide the relatively shorter and less frequent interruptions required to respond to contingencies than it is for them to reduce consumption for an entire peak period. Oak Ridge National Laboratory (ORNL) is conducting research on obtaining spinning reserve from large pumping loads and from residential and small commercial thermostat controlled heating, ventilation and air conditioning (HVAC) units. The technology selected for this project, Digi-Log's retrofit PTAC controller, offers significant advantages. To evaluate the availability of spinning reserve capacity from responsive heating and air conditioning loads, ORNL obtained data from a number of units operating over a year at a motel in the TVA service territory. A total of 24 PTAC units in as many rooms were fitted with Digi-Log's supervisory control unit that could be controlled from the motel front desk. Twelve of the rooms formed the group in which the controller was controlled from the hotel front desk only. The remaining twelve rooms were controlled by the occupant and formed the uncontrolled group. This enables us to evaluate the spinning reserve capacity from PTACS that were operating normally and from those under active energy management. A second generation of the Digi-Log controller that will respond quickly enough to provide spinning reserve

  19. Beam normal single spin asymmetry in forward angle inelastic electron-proton scattering using the q-weak apparatus

    NASA Astrophysics Data System (ADS)

    Nuruzzaman, FNU

    The Q-weak experiment in Hall-C at the Thomas Jefferson National Accelerator Facility has made the first direct measurement of the weak charge of the proton through the precision measurement of the parity-violating asymmetry in elastic electron-proton scattering at low momentum transfer. There is also a parity conserving Beam Normal Single Spin Asymmetry or transverse asymmetry (Bn) on H2 with a sin(phi)-like dependence due to two-photon exchange. If the size of elastic Bn is a few ppm, then a few percent residual transverse polarization in the beam, combined with small broken azimuthal symmetries in the detector, would require a few ppb correction to the Q-weak data. As part of a program of Bn background studies, we made the first measurement of Bn in the N-to-Delta(1232) transition using the Q-weak apparatus. The final transverse asymmetry, corrected for backgrounds and beam polarization, was found to be Bn = 42.82 +- 2.45 (stat) +- 16.07 (sys) ppm at beam energy Ebeam = 1.155 GeV, scattering angle theta = 8.3 degrees, and missing mass W = 1.2 GeV. Bn from electron-nucleon scattering is a unique tool to study the gamma*DeltaDelta form factors, and this measurement will help to improve the theoretical models on beam normal single spin asymmetry and thereby our understanding of the doubly virtual Compton scattering process. To help correct false asymmetries from beam noise, a beam modulation system was implemented to induce small position, angle, and energy changes at the target to characterize detector response to the beam jitter. Two air-core dipoles separated by ˜10 m were pulsed at a time to produce position and angle changes at the target, for virtually any tune of the beamline. The beam energy was modulated using an SRF cavity. The hardware and associated control instrumentation will be described in this dissertation. Preliminary detector sensitivities were extracted which helped to reduce the width of the measured asymmetry. The beam modulation system has

  20. Beam Normal Single Spin Asymmetry in Forward Angle Inelastic Electron-Proton Scattering using the Q-Weak Apparatus

    SciTech Connect

    ., Nuruzzaman

    2014-12-01

    The Q-weak experiment in Hall-C at the Thomas Jefferson National Accelerator Facility has made the first direct measurement of the weak charge of the proton through the precision measurement of the parity-violating asymmetry in elastic electron-proton scattering at low momentum transfer. There is also a parity conserving Beam Normal Single Spin Asymmetry or transverse asymmetry (B_n) on H_2 with a sin(phi)-like dependence due to two-photon exchange. If the size of elastic B_n is a few ppm, then a few percent residual transverse polarization in the beam, combined with small broken azimuthal symmetries in the detector, would require a few ppb correction to the Q-weak data. As part of a program of B_n background studies, we made the first measurement of B_n in the N-to-Delta(1232) transition using the Q-weak apparatus. The final transverse asymmetry, corrected for backgrounds and beam polarization, was found to be B_n = 42.82 ± 2.45 (stat) ± 16.07 (sys) ppm at beam energy E_beam = 1.155 GeV, scattering angle theta = 8.3 deg, and missing mass W = 1.2 GeV. B_n from electron-nucleon scattering is a unique tool to study the gamma^* Delta Delta form factors, and this measurement will help to improve the theoretical models on beam normal single spin asymmetry and thereby our understanding of the doubly virtual Compton scattering process. To help correct false asymmetries from beam noise, a beam modulation system was implemented to induce small position, angle, and energy changes at the target to characterize detector response to the beam jitter. Two air-core dipoles separated by ~10 m were pulsed at a time to produce position and angle changes at the target, for virtually any tune of the beamline. The beam energy was modulated using an SRF cavity. The hardware and associated control instrumentation will be described in this dissertation. Preliminary detector sensitivities were extracted which helped to reduce the width of the measured asymmetry. The beam modulation system

  1. Modeling the Spin Motor Current of the International Space Station's Control Moment Gyroscopes

    NASA Technical Reports Server (NTRS)

    Pereira, Miguel A.

    2008-01-01

    The International Space Station (ISS) attitude control is provided by two means: The Russian Segment uses thrusters and the U.S. Segment uses double-gimbaled control moment gyroscopes (CMG). CMGs are used as momentum exchange devices, providing non propulsive attitude control for the vehicle. The CMGs are very important for the ISS program because, first, they save propellant - which needs to be transferred to the Station in special cargo vehicles - and, second, they provide the microgravity environment on the Station - which is necessary for scientific experiments planned for the ISS mission. Since 2002, when one of the CMG on the ISS failed, all CMGs are closely monitored. High gimbal rates, vibration spikes, unusual variations of spin motor current and bearing temperatures are of great concern, since these parameters are the CMG health indicators. The telemetry analysis of these and some other CMG parameters is used to determine constrains and make changes to the CMGs operation on board. These CMG limitations, in turn, may limit the ISS attitude control capabilities and may be critical to ISS operation. Therefore, it is important to know whether the CMG parameter is nominal or out of family, and why. The goal of this project is to analyze an important CMG parameter - spin motor current. Some operational decisions are made now based on the spin motor current signatures. The spin motor current depends on gimbal rates, ISS rates, and spin bearing friction. The spin bearing friction in turn depends on the bearing temperatures, wheel rates, normal load - which is a function of gimbal and wheel rates - lubrication, etc. The first task of this project is to create a spin motor current mathematical model based on CMG dynamics model and the current knowledge on bearing friction in microgravity.

  2. Room-temperature spin-polarized organic light-emitting diodes with a single ferromagnetic electrode

    SciTech Connect

    Ding, Baofu Alameh, Kamal; Song, Qunliang

    2014-05-19

    In this paper, we demonstrate the concept of a room-temperature spin-polarized organic light-emitting diode (Spin-OLED) structure based on (i) the deposition of an ultra-thin p-type organic buffer layer on the surface of the ferromagnetic electrode of the Spin-OLED and (ii) the use of oxygen plasma treatment to modify the surface of that electrode. Experimental results demonstrate that the brightness of the developed Spin-OLED can be increased by 110% and that a magneto-electroluminescence of 12% can be attained for a 150 mT in-plane magnetic field, at room temperature. This is attributed to enhanced hole and room-temperature spin-polarized injection from the ferromagnetic electrode, respectively.

  3. The First Transverse Single Spin Measurement in High Energy Polarized Proton-Nucleus Collision at the PHENIX experiment at RHIC

    NASA Astrophysics Data System (ADS)

    Nakagawa, I.

    2016-08-01

    Large single spin asymmetries in very forward neutron production seen using the PHENIX zero-degree calorimeters are a long established feature of transversely polarized proton-proton collisions at RHIC. Neutron production near zero degrees is well described by the one-pion exchange framework. The absorptive correction to the OPE generates the asymmetry as a consequence of a phase shift between the spin flip and non-spin flip amplitudes. However, the amplitude predicted by the OPE is too small to explain the large observed asymmetries. A model introducing interference of pion and a 1-Reggeon exchanges has been successful in reproducing the experimental data. During the RHIC experiment in year 2015, RHIC delivered polarized proton collisions with Au and Al nuclei for the first time, enabling the exploration of the mechanism of transverse single-spin asymmetries with nuclear collisions. The observed asymmetries showed surprisingly strong A-dependence in the inclusive forward neutron production, while the existing framework which was successfull in p+p only predicts moderate A- dependence. Thus the observed data are absolutely unexpected and unpredicted. In this report, experimental and theoretical efforts are discussed to disentangle the observed A-dependence using somewhat semi-inclusive type measurements and Monte-Carlo study, respectively.

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

    PubMed

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

    2015-01-01

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

  5. SKRYN: A fast semismooth-Krylov-Newton method for controlling Ising spin systems

    NASA Astrophysics Data System (ADS)

    Ciaramella, G.; Borzì, A.

    2015-05-01

    The modeling and control of Ising spin systems is of fundamental importance in NMR spectroscopy applications. In this paper, two computer packages, ReHaG and SKRYN, are presented. Their purpose is to set-up and solve quantum optimal control problems governed by the Liouville master equation modeling Ising spin-1/2 systems with pointwise control constraints. In particular, the MATLAB package ReHaG allows to compute a real matrix representation of the master equation. The MATLAB package SKRYN implements a new strategy resulting in a globalized semismooth matrix-free Krylov-Newton scheme. To discretize the real representation of the Liouville master equation, a norm-preserving modified Crank-Nicolson scheme is used. Results of numerical experiments demonstrate that the SKRYN code is able to provide fast and accurate solutions to the Ising spin quantum optimization problem.

  6. The Effects of Negative Differential Resistance, Bipolar Spin-Filtering, and Spin-Rectifying on Step-Like Zigzag Graphene Nanoribbons Heterojunctions with Single or Double Edge-Saturated Hydrogen

    NASA Astrophysics Data System (ADS)

    Wang, Lihua; Zhao, Jianguo; Ding, Bingjun; Guo, Yong

    2016-09-01

    In this study, we investigated the spin-resolved transport aspects of step-like zigzag graphene ribbons (ZGNRs) with single or double edge-saturated hydrogen using a method that combined the density functional theory with the nonequilibrium Green's function method under the local spin density approximation. We found that, when the ZGNR-based heterojunctions were in a parallel or antiparallel layout, negative differential resistance, the maximum bipolar spin-filtering, and spin-rectifying effects occurred synchronously except for the case of spin-down electrons in the parallel magnetic layouts. Interestingly, these spin-resolved transport properties were almost unaffected by altering the widths of the two component ribbons. Therefore, step-like ZGNR heterojunctions are promising for use in designing high-performance multifunctional spintronic devices.

  7. Nuclear spin-lattice relaxation at field-induced level crossings in a Cr8F8 pivalate single crystal

    NASA Astrophysics Data System (ADS)

    Yamamoto, Shoji

    2016-01-01

    We construct a microscopic theory for the proton spin-lattice relaxation-rate 1 / T1 measurements around field-induced level crossings in a single crystal of the trivalent chromium ion wheel complex [Cr8F8(OOCtBu)16] at sufficiently low temperatures [E. Micotti et al., Phys. Rev. B 72 (2005) 020405(R)]. Exactly diagonalizing a well-equipped spin Hamiltonian for the individual clusters and giving further consideration to their possible interactions, we reveal the mechanism of 1 / T1 being single-peaked normally at the first level crossing but double-peaked intriguingly around the second level crossing. We wipe out the doubt about poor crystallization and find out a solution-intramolecular alternating Dzyaloshinsky-Moriya interaction combined with intermolecular coupling of antiferromagnetic character, each of which is so weak as several tens of mK in magnitude.

  8. Single and double spin asymmetries for deeply virtual Compton scattering measured with CLAS and a longitudinally polarized proton target

    SciTech Connect

    Pisano, S.; Biselli, A.; Niccolai, S.; Seder, E.; Guidal, M.; Mirazita, M.; Adhikari, K. P.; Adikaram, D.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Avakian, H.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Bosted, P.; Briscoe, B.; Brock, J.; Brooks, W. K.; Burkert, V. D.; Carlin, C.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Compton, N.; Contalbrigo, M.; Cortes, O.; Crabb, D. G.; Crede, V.; D' Angelo, A.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fersch, R.; Filippi, A.; Fleming, J. A.; Fradi, A.; Garillon, B.; Garcon, M.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guo, L.; Hafidi, K.; Hanretty, C.; Hattawy, M.; Hicks, K.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jenkins, D.; Jiang, X.; Jo, H. S.; Joo, K.; Joosten, S.; Keith, C. D.; Keller, D.; Kim, A.; Kim, W.; Klein, F. J.; Kubarovsky, V.; Kuhn, S. E.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacCormick, M.; MacGregor, Ian J. D.; Mayer, M.; McKinnon, B.; Meekins, D. G.; Meyer, C. A.; Mokeev, V.; Montgomery, R. A.; Moody, C. I.; Munoz Camacho, C.; Nadel-Turonski, P.; Osipenko, M.; Ostrovidov, A. I.; Park, K.; Phelps, W.; Phillips, J. J.; Pogorelko, O.; Price, J. W.; Procureur, S.; Prok, Y.; Puckett, A. J. R.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatie, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Skorodumina, I.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Stoler, P.; Strauch, S.; Sytnik, V.; Tian, Ye; Tkachenko, S.; Turisini, M.; Ungaro, M.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; Zonta, I.

    2015-03-19

    Single-beam, single-target, and double-spin asymmetries for hard exclusive photon production on the proton e→p→e'p'γ are presented. The data were taken at Jefferson Lab using the CLAS detector and a longitudinally polarized 14NH3 target. The three asymmetries were measured in 165 4-dimensional kinematic bins, covering the widest kinematic range ever explored simultaneously for beam and target-polarization observables in the valence quark region. The kinematic dependences of the obtained asymmetries are discussed and compared to the predictions of models of Generalized Parton Distributions. As a result, the measurement of three DVCS spin observables at the same kinematic points allows a quasi-model-independent extraction of the imaginary parts of the H and H~ Compton Form Factors, which give insight into the electric and axial charge distributions of valence quarks in the proton.

  9. Controllable Quantum State Transfer Between a Josephson Charge Qubit and an Electronic Spin Ensemble

    NASA Astrophysics Data System (ADS)

    Yan, Run-Ying; Wang, Hong-Ling; Feng, Zhi-Bo

    2016-01-01

    We propose a theoretical scheme to implement controllable quantum state transfer between a superconducting charge qubit and an electronic spin ensemble of nitrogen-vacancy centers. By an electro-mechanical resonator acting as a quantum data bus, an effective interaction between the charge qubit and the spin ensemble can be achieved in the dispersive regime, by which state transfers are switchable due to the adjustable electrical coupling. With the accessible experimental parameters, we further numerically analyze the feasibility and robustness. The present scheme could provide a potential approach for transferring quantum states controllably with the hybrid system.

  10. Exact results of a mixed spin-1/2 and spin- S Ising model on a bathroom tile (4-8) lattice: Effect of uniaxial single-ion anisotropy

    NASA Astrophysics Data System (ADS)

    Strečka, Jozef

    2006-02-01

    Effect of uniaxial single-ion anisotropy upon magnetic properties of a mixed spin-1/2 and spin- S ( S⩾1) Ising model on a bathroom tile (4-8) lattice is examined within the framework of an exact star-triangle mapping transformation. Particular attention is focused on the phase diagrams established for several values of the quantum spin number S. It is shown that the mixed-spin bathroom tile lattice exhibits very similar phase boundaries as the mixed-spin honeycomb lattice whose critical points are merely slightly enhanced with respect to the former ones. The influence of uniaxial single-ion anisotropy upon the total magnetization vs. temperature dependence is particularly investigated as well.

  11. Optically controlled spin-polarization memory effect on Mn delta-doped heterostructures

    PubMed Central

    Balanta, M. A. G.; Brasil, M. J. S. P.; Iikawa, F.; Mendes, Udson C.; Brum, J. A.; Danilov, Yu. A.; Dorokhin, M. V.; Vikhrova, O. V.; Zvonkov, B. N.

    2016-01-01

    We investigated the dynamics of the interaction between spin-polarized photo-created carriers and Mn ions on InGaAs/GaAs: Mn structures. The carriers are confined in an InGaAs quantum well and the Mn ions come from a Mn delta-layer grown at the GaAs barrier close to the well. Even though the carriers and the Mn ions are spatially separated, the interaction between them is demonstrated by time-resolved spin-polarized photoluminescence measurements. Using a pre-pulse laser excitation with an opposite circular-polarization clearly reduces the polarization degree of the quantum-well emission for samples where a strong magnetic interaction is observed. The results demonstrate that the Mn ions act as a spin-memory that can be optically controlled by the polarization of the photocreated carriers. On the other hand, the spin-polarized Mn ions also affect the spin-polarization of the subsequently created carriers as observed by their spin relaxation time. These effects fade away with increasing time delays between the pulses as well as with increasing temperatures. PMID:27080310

  12. Two-photon interference at telecom wavelengths for time-bin-encoded single photons from quantum-dot spin qubits

    NASA Astrophysics Data System (ADS)

    Yu, Leo; Natarajan, Chandra M.; Horikiri, Tomoyuki; Langrock, Carsten; Pelc, Jason S.; Tanner, Michael G.; Abe, Eisuke; Maier, Sebastian; Schneider, Christian; Höfling, Sven; Kamp, Martin; Hadfield, Robert H.; Fejer, Martin M.; Yamamoto, Yoshihisa

    2015-11-01

    Practical quantum communication between remote quantum memories rely on single photons at telecom wavelengths. Although spin-photon entanglement has been demonstrated in atomic and solid-state qubit systems, the produced single photons at short wavelengths and with polarization encoding are not suitable for long-distance communication, because they suffer from high propagation loss and depolarization in optical fibres. Establishing entanglement between remote quantum nodes would further require the photons generated from separate nodes to be indistinguishable. Here, we report the observation of correlations between a quantum-dot spin and a telecom single photon across a 2-km fibre channel based on time-bin encoding and background-free frequency downconversion. The downconverted photon at telecom wavelengths exhibits two-photon interference with another photon from an independent source, achieving a mean wavepacket overlap of greater than 0.89 despite their original wavelength mismatch (900 and 911 nm). The quantum-networking operations that we demonstrate will enable practical communication between solid-state spin qubits across long distances.

  13. Two-photon interference at telecom wavelengths for time-bin-encoded single photons from quantum-dot spin qubits

    PubMed Central

    Yu, Leo; Natarajan, Chandra M.; Horikiri, Tomoyuki; Langrock, Carsten; Pelc, Jason S.; Tanner, Michael G.; Abe, Eisuke; Maier, Sebastian; Schneider, Christian; Höfling, Sven; Kamp, Martin; Hadfield, Robert H.; Fejer, Martin M.; Yamamoto, Yoshihisa

    2015-01-01

    Practical quantum communication between remote quantum memories rely on single photons at telecom wavelengths. Although spin-photon entanglement has been demonstrated in atomic and solid-state qubit systems, the produced single photons at short wavelengths and with polarization encoding are not suitable for long-distance communication, because they suffer from high propagation loss and depolarization in optical fibres. Establishing entanglement between remote quantum nodes would further require the photons generated from separate nodes to be indistinguishable. Here, we report the observation of correlations between a quantum-dot spin and a telecom single photon across a 2-km fibre channel based on time-bin encoding and background-free frequency downconversion. The downconverted photon at telecom wavelengths exhibits two-photon interference with another photon from an independent source, achieving a mean wavepacket overlap of greater than 0.89 despite their original wavelength mismatch (900 and 911 nm). The quantum-networking operations that we demonstrate will enable practical communication between solid-state spin qubits across long distances. PMID:26597223

  14. Two-photon interference at telecom wavelengths for time-bin-encoded single photons from quantum-dot spin qubits.

    PubMed

    Yu, Leo; Natarajan, Chandra M; Horikiri, Tomoyuki; Langrock, Carsten; Pelc, Jason S; Tanner, Michael G; Abe, Eisuke; Maier, Sebastian; Schneider, Christian; Höfling, Sven; Kamp, Martin; Hadfield, Robert H; Fejer, Martin M; Yamamoto, Yoshihisa

    2015-11-24

    Practical quantum communication between remote quantum memories rely on single photons at telecom wavelengths. Although spin-photon entanglement has been demonstrated in atomic and solid-state qubit systems, the produced single photons at short wavelengths and with polarization encoding are not suitable for long-distance communication, because they suffer from high propagation loss and depolarization in optical fibres. Establishing entanglement between remote quantum nodes would further require the photons generated from separate nodes to be indistinguishable. Here, we report the observation of correlations between a quantum-dot spin and a telecom single photon across a 2-km fibre channel based on time-bin encoding and background-free frequency downconversion. The downconverted photon at telecom wavelengths exhibits two-photon interference with another photon from an independent source, achieving a mean wavepacket overlap of greater than 0.89 despite their original wavelength mismatch (900 and 911 nm). The quantum-networking operations that we demonstrate will enable practical communication between solid-state spin qubits across long distances.

  15. Conductance and spin-filter effects of oxygen-incorporated Au, Cu, and Fe single-atom chains

    SciTech Connect

    Zheng, Xiaolong; Xie, Yi-Qun Ye, Xiang; Ke, San-Huang

    2015-01-28

    We studied the spin-polarized electron transport in oxygen-incorporated Au, Cu, and Fe single-atom chains (SACs) by first-principles calculations. We first investigated the mechanism responsible for the low conductance (<1G{sub 0}) of the Au and Cu SACs in an oxygen environment reported in recent experiments. We found that for the Au SACs, the low conductance plateau around 0.6G{sub 0} can be attributed to a distorted chain doped with a single oxygen atom, while the 0.1G{sub 0} conductance comes from a linear chain incorporated with an oxygen molecule and is caused by an antibonding state formed by oxygen's occupied frontier orbital with d{sub z} orbitals of adjacent Au atoms. For the Cu SACs, the conductance about 0.3G{sub 0} is ascribed to a special configuration that contains Cu and O atoms in an alternating sequence. This exhibits an even-odd conductance oscillation with an amplitude of ∼0.1G{sub 0}. In contrast, for the alternating Fe-O SACs, conductance overall decreases with an increase in O atoms and it approaches nearly zero for the chain with more than four O atoms. While the Cu-O SACs behave as perfect spin filters for one spin channel due to the half metallic nature, the Fe-O SACs can serve as perfect spin filters for two spin channels depending on the polarity of the applied gate voltage.

  16. Electric-field control of spin-orbit torque in a magnetically doped topological insulator

    NASA Astrophysics Data System (ADS)

    Fan, Yabin; Kou, Xufeng; Upadhyaya, Pramey; Shao, Qiming; Pan, Lei; Lang, Murong; Che, Xiaoyu; Tang, Jianshi; Montazeri, Mohammad; Murata, Koichi; Chang, Li-Te; Akyol, Mustafa; Yu, Guoqiang; Nie, Tianxiao; Wong, Kin L.; Liu, Jun; Wang, Yong; Tserkovnyak, Yaroslav; Wang, Kang L.

    2016-04-01

    Electric-field manipulation of magnetic order has proved of both fundamental and technological importance in spintronic devices. So far, electric-field control of ferromagnetism, magnetization and magnetic anisotropy has been explored in various magnetic materials, but the efficient electric-field control of spin-orbit torque (SOT) still remains elusive. Here, we report the effective electric-field control of a giant SOT in a Cr-doped topological insulator (TI) thin film using a top-gate field-effect transistor structure. The SOT strength can be modulated by a factor of four within the accessible gate voltage range, and it shows strong correlation with the spin-polarized surface current in the film. Furthermore, we demonstrate the magnetization switching by scanning gate voltage with constant current and in-plane magnetic field applied in the film. The effective electric-field control of SOT and the giant spin-torque efficiency in Cr-doped TI may lead to the development of energy-efficient gate-controlled spin-torque devices compatible with modern field-effect semiconductor technologies.

  17. Electric-field control of spin-orbit torque in a magnetically doped topological insulator.

    PubMed

    Fan, Yabin; Kou, Xufeng; Upadhyaya, Pramey; Shao, Qiming; Pan, Lei; Lang, Murong; Che, Xiaoyu; Tang, Jianshi; Montazeri, Mohammad; Murata, Koichi; Chang, Li-Te; Akyol, Mustafa; Yu, Guoqiang; Nie, Tianxiao; Wong, Kin L; Liu, Jun; Wang, Yong; Tserkovnyak, Yaroslav; Wang, Kang L

    2016-04-01

    Electric-field manipulation of magnetic order has proved of both fundamental and technological importance in spintronic devices. So far, electric-field control of ferromagnetism, magnetization and magnetic anisotropy has been explored in various magnetic materials, but the efficient electric-field control of spin-orbit torque (SOT) still remains elusive. Here, we report the effective electric-field control of a giant SOT in a Cr-doped topological insulator (TI) thin film using a top-gate field-effect transistor structure. The SOT strength can be modulated by a factor of four within the accessible gate voltage range, and it shows strong correlation with the spin-polarized surface current in the film. Furthermore, we demonstrate the magnetization switching by scanning gate voltage with constant current and in-plane magnetic field applied in the film. The effective electric-field control of SOT and the giant spin-torque efficiency in Cr-doped TI may lead to the development of energy-efficient gate-controlled spin-torque devices compatible with modern field-effect semiconductor technologies.

  18. Optimal control of a spinning double-pyramid Earth-pointing tethered formation

    NASA Astrophysics Data System (ADS)

    Williams, Paul

    2009-06-01

    The dynamics and control of a tethered satellite formation for Earth-pointing observation missions is considered. For most practical applications in Earth orbit, a tether formation must be spinning in order to maintain tension in the tethers. It is possible to obtain periodic spinning solutions for a triangular formation whose initial conditions are close to the orbit normal. However, these solutions contain significant deviations of the satellites on a sphere relative to the desired Earth-pointing configuration. To maintain a plane of satellites spinning normal to the orbit plane, it is necessary to utilize "anchors". Such a configuration resembles a double-pyramid. In this paper, control of a double-pyramid tethered formation is studied. The equations of motion are derived in a floating orbital coordinate system for the general case of an elliptic reference orbit. The motion of the satellites is derived assuming inelastic tethers that can vary in length in a controlled manner. Cartesian coordinates in a rotating reference frame attached to the desired spin frame provide a simple means of expressing the equations of motion, together with a set of constraint equations for the tether tensions. Periodic optimal control theory is applied to the system to determine sets of controlled periodic trajectories by varying the lengths of all interconnecting tethers (nine in total), as well as retrieval and simple reconfiguration trajectories. A modal analysis of the system is also performed using a lumped mass representation of the tethers.

  19. Shape- and Interface-Induced Control of Spin Dynamics of Two-Dimensional Bicomponent Magnonic Crystals.

    PubMed

    Choudhury, Samiran; Saha, Susmita; Mandal, Ruma; Barman, Saswati; Otani, YoshiChika; Barman, Anjan

    2016-07-20

    Controlled fabrication of periodically arranged embedded nanostructures with strong interelement interaction through the interface between the two different materials has great potential applications in spintronics, spin logic, and other spin-based communication devices. Here, we report the fabrication of two-dimensional bicomponent magnonic crystals in form of embedded Ni80Fe20 nanostructures in Co50Fe50 thin films by nanolithography. The spin wave (SW) spectra studied by a broadband ferromagnetic resonance spectroscopy showed a significant variation as the shape of the embedded nanostructure changes from circular to square. Significantly, in both shapes, a minimum in frequency is obtained at a negative value of bias field during the field hysteresis confirming the presence of a strong exchange coupling at the interface between the two materials, which can potentially increase the spin wave propagation velocity in such structures leading to faster gigahertz frequency magnetic communication and logic devices. The spin wave frequencies and bandgaps show bias field tunability, which is important for above device applications. Numerical simulations qualitatively reproduced the experimental results, and simulated mode profiles revealed the spatial distribution of the SW modes and internal magnetic fields responsible for this observation. Development of such controlled arrays of embedded nanostructures with improved interface can be easily applied to other forms of artificial crystals. PMID:27345034

  20. Gate-voltage control of spin interactions between electrons and nuclei in a semiconductor

    NASA Astrophysics Data System (ADS)

    Smet, J. H.; Deutschmann, R. A.; Ertl, F.; Wegscheider, W.; Abstreiter, G.; von Klitzing, K.

    2003-01-01

    Semiconductors are ubiquitous in device electronics, because their charge distributions can be conveniently manipulated with applied voltages to perform logic operations. Achieving a similar level of control over the spin degrees of freedom, either from electrons or nuclei, could provide intriguing prospects for information processing and fundamental solid-state physics issues. Here, we report procedures that carry out the controlled transfer of spin angular momentum between electrons-confined to two dimensions and subjected to a perpendicular magnetic field-and the nuclei of the host semiconductor, using gate voltages only. We show that the spin transfer rate can be enhanced near a ferromagnetic ground state of the electron system, and that the induced nuclear spin polarization can be subsequently stored and ‘read-out’. These techniques can also be combined into a spectroscopic tool to detect the low-energy collective excitations in the electron system that promote the spin transfer. The existence of such excitations is contingent on appropriate electron-electron correlations, and these can be tuned by changing, for example, the electron density via a gate voltage.