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Sample records for single spin control

  1. 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 properties, these measurements suggest that NV center sensors could be employed in a diverse range of applications such as intracellular thermometry, microfuidic thermometry, and scanning thermal microscopy. Finally, while the development of NV center technologies is motivated by the desirable properties of isolated defects in bulk diamond, the realization of many of these technologies, such as those using the spin as a proximal sensor, require a means to control the placement of NV centers within the diamond lattice. We demonstrate a method to pattern defect formation on sub-100-nm length scales using ion implantation and electron beam lithography techniques. The ability to engineer large scale arrays of NV centers with this method holds promise for a variety of applications in quantum information science and nanoscale sensing.

  2. Ultrafast coherent optical control of a single diamond spin

    NASA Astrophysics Data System (ADS)

    Bassett, L. C.; Heremans, F. J.; Awschalom, D. D.; Burkard, G.

    2013-03-01

    As an optically addressable solid-state electronic spin, the nitrogen-vacancy (NV) center in diamond has great promise for applications in quantum information science and metrology. At temperatures below ~ 10 K, the NV center's optical fine structure facilitates coherent coupling between the electronic spin and light, providing the means for all-optical spin control and other applications in quantum optics. Here, using ultrafast optical pump-probe techniques, we investigate the interplay of orbital, vibrational, and spin dynamics on timescales ranging from femtoseconds to nanoseconds. These techniques provide a flexible and powerful probe of orbital dynamics in the NV center's optically excited state, and enable optical spin control with sub-picosecond resolution. Work supported by AFOSR, ARO, and DARPA.

  3. Quantum Dot Spin Valves Controlled by Single Molecule Magnets

    NASA Astrophysics Data System (ADS)

    Rostamzadeh Renani, Fatemeh; Kirczenow, George

    2013-03-01

    We explore theoretically for the first time the properties of a new class of spintronic nano-devices in which the electrical resistance of a non-magnetic quantum dot contacted by non-magnetic electrodes is controlled by transition metal-based single molecule nanomagnets (SMMs) bound to the dot. Although the SMMs do not lie directly in the current path in these devices, we show that the relative orientation of their magnetic moments can strongly influence on the electric current passing through the device. If the magnetic moment of one of the SMMs is reversed by the application of a magnetic field, we predict a large change in the resistance of the dot, i.e., a strong spin valve effect. The mechanism is resonant conduction via molecular orbitals extending over the entire system. The spin valve is activated by a gate that tunes the transport resonances through the Fermi energy. Detailed results will be presented for the case of Mn12 SMMs bound to a gold quantum dot. This work was supported by CIFAR and NSERC.

  4. Fast Electrical Control of Single Electron Spins in Quantum Dots with Vanishing Influence from Nuclear Spins

    NASA Astrophysics Data System (ADS)

    Yoneda, J.; Otsuka, T.; Nakajima, T.; Takakura, T.; Obata, T.; Pioro-Ladrire, M.; Lu, H.; Palmstrm, C. J.; Gossard, A. C.; Tarucha, S.

    2014-12-01

    We demonstrate fast universal electrical spin manipulation with inhomogeneous magnetic fields. With fast Rabi frequency up to 127 MHz, we leave the conventional regime of strong nuclear-spin influence and observe a spin-flip fidelity >96 % , a distinct chevron Rabi pattern in the spectral-time domain, and a spin resonance linewidth limited by the Rabi frequency, not by the dephasing rate. In addition, we establish fast z rotations up to 54 MHz by directly controlling the spin phase. Our findings will significantly facilitate tomography and error correction with electron spins in quantum dots.

  5. Single-shot readout and microwave control of an electron spin in silicon

    NASA Astrophysics Data System (ADS)

    Morello, Andrea

    2011-03-01

    The electron spin of a donor in silicon is an excellent candidate for a solid-state qubit. It is known to have very long coherence and relaxation times in bulk, and several architectures have been proposed to integrate donor spin qubits with classical silicon microelectronics. Here we show the first experimental proof of single-shot readout of an electron spin in silicon. The device consists of implanted phosphorus donors, tunnel-coupled to a silicon Single-Electron Transistor (SET), where the SET island is used as a reservoir for spin-to-charge conversion. The large charge transfer signals allow readout fidelity > 90 % with 3 ? s response time. By measuring the occurrence of excited spin states as a function of wait time, we find spin lifetimes (T1) up to ~ 6 s at B = 1 . 5 T , and a magnetic-field dependence T1- 1 ~B5 consistent with that of phosphorus donors in silicon. In a subsequent experiment we have integrated the single-shot spin readout device with an on-chip microwave transmission line for coherent control of the electron spin. We have detected the spin resonance of a single electron, and observed two hyperfine-split resonance lines, consistent with Stark-shifted coupling to the 31P nuclear spin. Further experiments are underway to demonstrate coherent spin control and observe Rabi oscillations. This demonstrates the microwave control of a single spin, combined -- for the first time in the same experiment -- with electrically detected single-shot spin readout.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. 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

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  10. Excited-State Spectroscopy and Control of Single Spins in Diamond

    NASA Astrophysics Data System (ADS)

    Fuchs, G. D.

    2009-03-01

    Nitrogen Vacancy (NV) defect centers in diamond are a promising system for spin-based applications in quantum information and communication at room temperature. Using a combination of optical microscopy and spin resonance, the spin of individual NV centers can be initialized, manipulated and read out. These techniques have been used to study the long room temperature spin coherence times of NV centers as well as their interactions with nearby electrical and nuclear spins. There remain significant challenges, however, both in understanding the physics of these defects as well as the development of technologies based on their quantum properties. In particular, knowledge of the detailed structure of the orbital excited-state, which continues to be an active research area, is critical to ultra-fast quantum control schemes. Here we present recent experiments using single-spin resonant spectroscopy of the excited-state of an NV center at room temperature.ootnotetextG. D. Fuchs, V. V. Dobrovitski, R. Hanson, A. Batra, C. D. Weis, T. Schenkel, and D. D. Awschalom, Phys. Rev. Lett 101, 117601 (2008). We observe these spin levels over a broad range of magnetic fields allowing for a direct measurement of the zero-field splitting, g-factor and transverse anisotropy splitting. The latter of these is nearly zero in the ground-state spin levels, but plays an important role in the excited-state. In addition, we find strong hyperfine coupling between the nitrogen nuclear spin and the NV electronic spin in the excited-state. These findings will be discussed in the context of quantum control of single and coupled spins in diamond.

  11. Quantum computers based on electron spins controlled by ultrafast off-resonant single optical pulses.

    PubMed

    Clark, Susan M; Fu, Kai-Mei C; Ladd, Thaddeus D; Yamamoto, Yoshihisa

    2007-07-27

    We describe a fast quantum computer based on optically controlled electron spins in charged quantum dots that are coupled to microcavities. This scheme uses broadband optical pulses to rotate electron spins and provide the clock signal to the system. Nonlocal two-qubit gates are performed by phase shifts induced by electron spins on laser pulses propagating along a shared waveguide. Numerical simulations of this scheme demonstrate high-fidelity single-qubit and two-qubit gates with operation times comparable to the inverse Zeeman frequency. PMID:17678343

  12. 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.

  13. 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

  14. 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

  15. Control of the cavity reflectivity using a single quantum dot spin

    NASA Astrophysics Data System (ADS)

    Sun, Shuo; Kim, Hyochul; Solomon, Glenn; Waks, Edo

    2015-03-01

    The implementation of quantum network and distributive quantum information processing relies on interaction between stationary matter qubits and flying photons. The spin of a single electron or hole confined in a quantum dot is considered as promising matter qubit as it possesses microsecond coherence time and allows picosecond timescale control using optical pulses. The quantum dot spin can also interact with a photon by controlling the optical response of a strongly coupled cavity. Yet all the experimental demonstrations of the cavity spectrum control have used neutral dots. The spin-dependent cavity spectrum for a strongly coupled charged quantum dot and cavity system has not been reported. Here, we report an experimental realization of a spin-photon interface using a strongly coupled quantum dot and cavity system. We show large modulation of the cavity reflection spectrum by manipulating the spin states of the quantum dot. The spin-photon interface is crucial for realizing a quantum logic gate or generating hybrid entanglement between a quantum dot spin and a photon. Our results represent an important step towards semiconductor based quantum logic devices and on-chip quantum networks.

  16. 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

  17. Reversible Single Spin Control of Individual Magnetic Molecule by Hydrogen Atom Adsorption

    PubMed Central

    Liu, Liwei; Yang, Kai; Jiang, Yuhang; Song, Boqun; Xiao, Wende; Li, Linfei; Zhou, Haitao; Wang, Yeliang; Du, Shixuan; Ouyang, Min; Hofer, Werner A.; Castro Neto, Antonio H.; Gao, Hong-Jun

    2013-01-01

    The reversible control of a single spin of an atom or a molecule is of great interest in Kondo physics and a potential application in spin based electronics. Here we demonstrate that the Kondo resonance of manganese phthalocyanine molecules on a Au(111) substrate have been reversibly switched off and on via a robust route through attachment and detachment of single hydrogen atom to the magnetic core of the molecule. As further revealed by density functional theory calculations, even though the total number of electrons of the Mn ion remains almost the same in the process, gaining one single hydrogen atom leads to redistribution of charges within 3d orbitals with a reduction of the molecular spin state from S = 3/2 to S = 1 that directly contributes to the Kondo resonance disappearance. This process is reversed by a local voltage pulse or thermal annealing to desorb the hydrogen atom. PMID:23383378

  18. Reversible Control by Light of the High-Spin Low-Spin Elastic Interface inside the Bistable Region of a Robust Spin-Transition Single Crystal.

    PubMed

    Sy, Mouhamadou; Garrot, Damien; Slimani, Ahmed; Pez-Espejo, Miguel; Varret, Franois; Boukheddaden, Kamel

    2016-01-01

    By using a weak modulated laser intensity we have succeeded in reversibly controlling the dynamics of the spin-crossover (SC) single crystal [{Fe(NCSe)(py)2 }2 (m-bpypz)] inside the thermal hysteresis. The experiment could be repeated several times with a reproducible response of the high-spin low-spin interface and without crystal damage. In-depth investigations as a function of the amplitude and frequency of the excitation brought to light the existence of a cut-off frequency ca. 1.5?Hz. The results not only document the applicability of SC materials as actuators, memory devices, or switches, but also open a new avenue for the reversible photo-control of the spin transition inside the thermal hysteresis. PMID:26791883

  19. Local electrical control of a single-atom spin qubit in a continuous microwave field

    NASA Astrophysics Data System (ADS)

    Morello, Andrea; Laucht, Arne; Muhonen, Juha; Mohiyaddin, Fahd; Kalra, Rachpon; Dehollain, Juan; Freer, Solomon; Hudson, Fay; Veldhorst, Menno; Dzurak, Andrew; Itoh, Kohei; Rahman, Raijb; Klimeck, Gerhard; McCallum, Jeffrey; Jamieson, David

    2015-03-01

    An ideal physical system to encode quantum information should be well isolated from its environment, but locally addressable and readable. Kane's proposal for a silicon spin-based quantum computer suggested tuning the qubit in/out of resonance with a global oscillating magnetic field by applying a local electric field and exploiting the Stark shift of the electron-nuclear hyperfine interaction (`` A-gate''). We demonstrate universal single-qubit logic gates on both the electron and 31P nuclear spin of a single phosphorus atom in silicon, subject to an always-on microwave field, and operated via an A-gate controlled by nanometre-scale electrodes. The experiment is facilitated by the exceptionally sharp spin resonance frequencies in the nuclear-spin-free 28Si host material. Randomized benchmarking yields quantum gate fidelities >= 99 %, and the millisecond-long spin coherence times remain identical to those obtained by pulsed spin resonance. This method provides a natural pathway to address arbitrarily many qubits in large-scale quantum computers. Funded by the Australian Research Council (CE11E000127) and the U.S. Army Research Office (W911NF-13-1-0024).

  20. Robust entanglement in antiferromagnetic Heisenberg chains by single-spin optimal control

    SciTech Connect

    Wang Xiaoting; Schirmer, S. G.; Bayat, Abolfazl; Bose, Sougato

    2010-03-15

    We demonstrate how near-perfect entanglement (in fact arbitrarily close to maximal entanglement) can be generated between the end spins of an antiferromagnetic isotropic Heisenberg chain of length N, starting from the ground state in the N/2 excitation subspace, by applying a magnetic field along a given direction, acting on a single spin only. Temporally optimal magnetic fields to generate a singlet pair between the two end spins of the chain are calculated for chains up to length 20 using optimal control theory. The optimal fields are shown to remain effective in various nonideal situations including thermal fluctuations, magnetic field leakage, random system couplings, and decoherence. Furthermore, the quality of the entanglement generated can be substantially improved by taking these imperfections into account in the optimization. In particular, the optimal pulse of a given thermal initial state is also optimal for any other initial thermal state with lower temperature.

  1. Dynamical control of the spin transition inside the thermal hysteresis loop of a spin-crossover single crystal

    NASA Astrophysics Data System (ADS)

    Boukheddaden, Kamel; Sy, Mouhamadou; Paez-Espejo, Miguel; Slimani, Ahmed; Varret, François

    2016-04-01

    We have succeeded to achieve experimentally, using an adapted optical microscopy setup, the reversible control of the front transformation between the low-spin (LS)-high-spin (HS) interface in the spin-crossover (SC) single crystal [{Fe(NCSe)(py)2}2(m-bpypz)] undergoing a first-order transition at 112 K with a 7 K hysteresis width. For that, we first generate a phase separation state (a HS/LS interface at equilibrium) inside the hysteresis loop by tuning the light intensity of the microscope. In the second step, this intensity is monitored in such a way to drive, through a photo-heating process, the interface motion. This photo-control is found to be reversible, accurate and requiring a very small amount of energy. In addition the integrity of the crystal is maintained even after a large number of cycling. The experimental observations, are well described as a reaction diffusion process accounting for the front propagation and the photo-heating effects.

  2. 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).

  3. 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 example, the new Sector-Arc Slew and Dual-cone techniques are designed to overcome a specific restriction on attainable slew angle that is associated with the half-cone manoeuvre, giving one additional degree of freedom for designers to fine-tune.

  4. High-frequency electrical charge and spin control in a single InGaAs quantum dot

    NASA Astrophysics Data System (ADS)

    Nannen, J.; Quitsch, W.; Eliasson, S.; Kümmell, T.; Bacher, G.

    2012-01-01

    We report on the charging behavior of a single self-assembled InGaAs quantum dot with unpolarized and spin-polarized electrons under direct current (DC) and high-frequency biasing. The tunnel coupling of the quantum dot to a spin-polarized electron reservoir leads to characteristic voltage dependence of the polarization of the neutral and the negatively charged exciton emissions in a magnetic field under DC biasing conditions. Via high-frequency adaptation of the device, electrical control of the charge state of the single quantum dot in the gigahertz regime is achieved. A technique for optical preparation of single holes and subsequent electrical charging via high-frequency voltage pulses allows for an ultrafast injection and readout of spin-polarized electrons on a subnanosecond timescale.

  5. 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.

  6. Control of electron spin decoherence in nuclear spin baths

    NASA Astrophysics Data System (ADS)

    Liu, Ren-Bao

    2011-03-01

    Nuclear spin baths are a main mechanism of decoherence of spin qubits in solid-state systems, such as quantum dots and nitrogen-vacancy (NV) centers of diamond. The decoherence results from entanglement between the electron and nuclear spins, established by quantum evolution of the bath conditioned on the electron spin state. When the electron spin is flipped, the conditional bath evolution is manipulated. Such manipulation of bath through control of the electron spin not only leads to preservation of the center spin coherence but also demonstrates quantum nature of the bath. In an NV center system, the electron spin effectively interacts with hundreds of 13 C nuclear spins. Under repeated flip control (dynamical decoupling), the electron spin coherence can be preserved for a long time (> 1 ms) . Thereforesomecharacteristicoscillations , duetocouplingtoabonded 13 C nuclear spin pair (a dimer), are imprinted on the electron spin coherence profile, which are very sensitive to the position and orientation of the dimer. With such finger-print oscillations, a dimer can be uniquely identified. Thus, we propose magnetometry with single-nucleus sensitivity and atomic resolution, using NV center spin coherence to identify single molecules. Through the center spin coherence, we could also explore the many-body physics in an interacting spin bath. The information of elementary excitations and many-body correlations can be extracted from the center spin coherence under many-pulse dynamical decoupling control. Another application of the preserved spin coherence is identifying quantumness of a spin bath through the back-action of the electron spin to the bath. We show that the multiple transition of an NV center in a nuclear spin bath can have longer coherence time than the single transition does, when the classical noises due to inhomogeneous broadening is removed by spin echo. This counter-intuitive result unambiguously demonstrates the quantumness of the nuclear spin bath. This work was supported by Hong Kong RGC/GRF CUHK402207, CUHK402209, and CUHK402410. The author acknowledges collaboration with Nan Zhao, Jian-Liang Hu, Sai Wah Ho, Jones T. K. Wan, and Jiangfeng Du.

  7. Electrical control of the spin-orbit coupling in GaAs from single to double and triple wells

    NASA Astrophysics Data System (ADS)

    Wang, W.; Li, X. M.; Fu, J. Y.

    2015-12-01

    We consider a realistic GaAs/Al0.3Ga0.7As well, inside which there are either one or two additional AlxGa1 - xAs barriers embedded, with two occupied electron subbands ν = 1, 2. By varying the Al content x in the AlxGa1 - xAs layer, we investigate the electrical control of the spin-orbit (SO) interaction, i.e., intrasubband Rashba (Dresselhaus) αν (βν) and intersubband Rashba (Dresselhaus) η (Γ), in the course of the transition of our system from single to double and triple wells. At x = 0 (single well), the scenario of SO terms is usual, e.g., α1 and α2 have the same sign and both change almost linearly as functions of an external gate voltage Vg. In contrast, when x away from zero and only one AlxGa1 - xAs barrier embedded (double well), α1 and α2 tend to have opposite signs, and α2 first increases with Vg, while peaks at some point depending on x. For a larger value of x, α2 increases with Vg more abruptly till it peaks. As opposed to α1 and α2, the intrasubband Dresselhaus terms βν have a relatively weak dependence on Vg, and β1 and β2 become close as x increases. As for the intersubband SO terms, at x = 0, the Rashba coupling η remains essentially constant, while the Dresselhaus Γ changes almost linearly with Vg. When x is nonzero, on the one hand, both η and Γ have a sensitive dependence on Vg near the symmetric configuration; on the other hand, right at the symmetric configuration η exhibits the highest while Γ vanishes. In the case of our system having two additional AlxGa1 - xAs barriers (triple well), we find that the gate dependence of SO terms becomes more smooth and βν becomes more stronger. The persistent-spin-helix symmetry of the two subbands is also discussed. These results are expected to be important for a broad control of the SO interaction in semiconductor nanostructures.

  8. Single spin detection by magnetic resonance force microscopy

    NASA Astrophysics Data System (ADS)

    Rugar, Daniel

    2005-03-01

    Single spin detection by magnetic resonance force microscopy (MRFM) is based on ultrasensitive measurements of the attonewton magnetic force between a spin and a nearby magnetic tip. Interest in the technique is driven by potential applications to three-dimensional atomic resolution imaging and by fundamental interest in the detection and manipulation of individual quantum objects. This talk describes the basic principles of MRFM and discusses recent results that demonstrated the detection of an individual electron spin buried below the surface of a silicon dioxide sample. Various innovations that led to single spin detection will be described, including ultrasensitive force detection, spin-friendly micromechanical cantilevers and methods to measure and control statistical polarization in small spin ensembles. Future prospects for quantum state readout and for extension to nuclear spin detection will be discussed. This work was performed in collaboration with H. J. Mamin, R. Budakian and B. W. Chui.

  9. Coherent manipulation of single electronic and nuclear spins in diamond

    NASA Astrophysics Data System (ADS)

    Childress, Lilian

    2008-05-01

    The complex environment of solid-state systems poses a central challenge for solid-state realizations of quantum bits. Nevertheless, we show that the solid-state environment of a single spin can be understood, controlled, and even utilized as a resource. Using coherent manipulation of a single electronic spin associated with a nitrogen-vacancy (NV) center in diamond, we probe the ^13C nuclear spin bath formed by impurities in the surrounding diamond lattice. We show that this environment is effectively separated into a set of individual, proximal ^13C nuclear spins which are coupled coherently to the electron spin, and the remainder of the ^13C nuclear spins, which cause the loss of coherence. By manipulating the NV center via microwave and optical excitation, we demonstrate robust, room-temperature initialization of the two-qubit register formed by the electronic spin and the nearest-neighbor ^13C nuclear spin. Within this register, arbitrary quantum states can be transferred between the electronic and nuclear spin, while the nuclear spin qubit can be well isolated from the electron spin, even during optical polarization and measurement of the electronic state. Finally, we observe coherent interactions between individual nuclear spins, and demonstrate that they have excellent coherence properties, approaching those of isolated atoms and ions. Combined with teleportation-based quantum gates, such registers offer a basis for scalable, optically coupled quantum information systems.

  10. 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.

  11. 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.

  12. Exploring the Single Atom Spin State by Electron Spectroscopy.

    PubMed

    Lin, Yung-Chang; Teng, Po-Yuan; Chiu, Po-Wen; Suenaga, Kazu

    2015-11-13

    To control the spin state of an individual atom is an ultimate goal for spintronics. A single atom magnet, which may lead to a supercapacity memory device if realized, requires the high-spin state of an isolated individual atom. Here, we demonstrate the realization of well isolated transition metal (TM) atoms fixed at atomic defects sparsely dispersed in graphene. Core-level electron spectroscopy clearly reveals the high-spin state of the individual TM atoms at the divacancy or edge of the graphene layer. We also show for the first time that the spin state of single TM atoms systematically varies with the coordination of neighboring nitrogen or oxygen atoms. These structures can be thus regarded as the smallest components of spintronic devices with controlled magnetic behavior. PMID:26613462

  13. Exploring the Single Atom Spin State by Electron Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lin, Yung-Chang; Teng, Po-Yuan; Chiu, Po-Wen; Suenaga, Kazu

    2015-11-01

    To control the spin state of an individual atom is an ultimate goal for spintronics. A single atom magnet, which may lead to a supercapacity memory device if realized, requires the high-spin state of an isolated individual atom. Here, we demonstrate the realization of well isolated transition metal (TM) atoms fixed at atomic defects sparsely dispersed in graphene. Core-level electron spectroscopy clearly reveals the high-spin state of the individual TM atoms at the divacancy or edge of the graphene layer. We also show for the first time that the spin state of single TM atoms systematically varies with the coordination of neighboring nitrogen or oxygen atoms. These structures can be thus regarded as the smallest components of spintronic devices with controlled magnetic behavior.

  14. Optical control of electron spins in diamond

    NASA Astrophysics Data System (ADS)

    Golter, David Andrew, II

    By choosing the right system and using the right techniques, it is possible to achieve reliable control of an individual quantum system in a solid. Certain atom-like solid-state systems are especially suited for this goal. The electron spin of the diamond nitrogen-vacancy (NV) impurity center is a leader among such systems and has featured in a great deal of recent experimental work in the context of various quantum technologies. By extending optical control for the NV center we increase the utility of this system, opening it up to fresh applications in quantum optics. Doing quantum control with a solid-state spin comes with its own challenges. In particular it can be difficult to simultaneously isolate single systems, both for control and from environment-induced decoherence, while also coupling multiple systems together in a controlled way. A goal of the work presented in this dissertation is to develop techniques for answering this problem in the NV center. Optical control, as opposed to the microwave control usually used for state manipulation in the NV center, would make it easier to address only one spin system at a time. We demonstrate such control using two methods, two-photon optically driven Rabi oscillations and stimulated Raman adiabatic passage. These both have the added advantage that by using Raman-resonant, dipole-detuned optical fields, they protect the spin state from the decoherence normally associated with the optical transitions. Furthermore, we see that this electron spin control is nuclear spin dependent, providing a mechanism for coupling these two spin systems. We also investigate a decoherence reduction technique that involves coupling continuous microwave fields to the spin states. The resulting "dressed states" are shielded from spin-bath-induced magnetic field fluctuations. We confirm this using optical coherent population trapping measurements which we have also developed in the NV center. We show that these measurements are sensitive to nuclear spin states as well as to dressed states. These results supply the missing piece, optical spin manipulation, to control schemes that are all-optical, and they demonstrate ways to significantly push back the decoherence limit. This dissertation includes previously published and unpublished co-authored material.

  15. Single-shot readout of an electron spin in silicon

    NASA Astrophysics Data System (ADS)

    Morello, Andrea; Pla, Jarryd; Zwanenburg, Floris; Chan, Kok Wai; Huebl, Hans; Nugroho, Christopher; Yang, Changyi; van Donkelaar, Jessica; Alves, Andrew; Jamieson, David; Escott, Christopher; Hollenberg, Lloyd; Clark, Robert; Dzurak, Andrew

    2010-03-01

    The electron spin of a donor in silicon is an excellent candidate for a solid-state qubit. It is known to have very long coherence and relaxation times in bulk, and several architectures have been proposed to integrate donor spin qubits with classical silicon microelectronics. Here we show the first experimental proof of single-shot readout of an electron spin in silicon. This breakthrough has been obtained with a device consisting of implanted phosphorus donors, tunnel-coupled to a silicon Single-Electron Transistor (Si-SET), where the SET island is used as a reservoir for spin-to-charge conversion. The charge transfer signals are exceptionally large, and allow time-resolved measurements of spin-dependent tunneling on a 10 ?s scale. By measuring the occurrence of excited spin states as a function of wait time, we find spin lifetimes up to 1 s at B=1.75 T. Further experiments are underway to integrate this readout method with coherent spin control.

  16. Voltage-controlled spin precession

    NASA Astrophysics Data System (ADS)

    Zainuddin, A. N. M.; Hong, S.; Siddiqui, L.; Srinivasan, S.; Datta, S.

    2011-10-01

    Spin-transport properties of a lateral spin-valve structure originating from spin precession in its two-dimensional semiconducting channel under the influence of Rashba spin-orbit (RSO) coupling are explored. The effect of the finite extent of the injecting and detecting contact pads, along the length of the channel, on the spin signals is studied in these structures using (1) a simple theoretical treatment leading to analytical expressions for spin-dependent voltages derived using the stationary phase approximation, and (2) a more rigorous theoretical treatment based on nonequilibrium Green’s function formalism to calculate these voltages, in a nonlocal spin-valve setup. Using both these approaches, it is found that the oscillation in spin voltages, which is observed by varying RSO when the magnetization directions of the injector and detector are parallel to the current flow, reduces in amplitude and shifts in phase for contact pads having finite length when compared to the corresponding results for a zero length (point-contact) limit. The amplitude and phase of the oscillation can be recovered to its point-contact limit if the RSO underneath the contacts is assumed to be zero. These models were compared against a recent experiment, and it is found that certain aspects of the experiment can be described well while some other aspects deserve further investigation. Factors that could have influenced the experiment and thereby could explain the discrepancy with the theory were analyzed. Conditions for observing Hanle oscillation in such a structure is discussed. Finally, the possibility of controlling the magnetization reversal via the gate is discussed, which could extend and quantify the ‘Datta-Das’ effect for voltage controlled spin-precession.

  17. Control Spin Current and Data Recording on Spin Storage Medium

    NASA Astrophysics Data System (ADS)

    Krupa, M. M.

    2014-12-01

    The paper presents the results of experimental studies of the physical mechanisms and dynamics of magnetization reversal of the films Al2O3/Tb25Co5Fe70/Al2O3, Al2O3/Tb22Co5Fe73/Al2O3, Al2O3/Tb19Co5Fe76/Al2O3, Al2O3/Co30Fe70/Al2O3 with a single magnetic layer and the films Al2O3/Tb22Co5Fe73/Pr6O11/Tb19Co5Fe76/Al2O3, Al2O3/Co80Fe20/Pr6O11/Co30Fe70/Al2O3 with two magnetic layers radiated by picosecond (?i ? 80 ps) and femtosecond (?i ? 130 fs) laser pulses. The experimental samples of spin transistors and data recording devices on the spin storage medium are also described. The results of studies have shown that magnetic switching effects in the nanolayers under femtosecond laser pulses can be used for creation of systems of high-speed controlling of spin currents with the response time ? ? 10-11s. Conclusions from the studies are the following: thermomagnetic switching under the influence of an external magnetic field or a demagnetization field, magnetic switching of antiferromagnetic films under the influence of an effective internal field of antiferromagnetic interaction between magnetic sublattices rare-earth and transitive metals, magnetic switching under the influence of a magnetic field of the inverse Faraday effect, or under the influence of a magnetic field of a spin current. The magnetic switching of magnetic layers under action of the magnetic field of a spin current is the most important for practical use in elements of spintronics. This mechanism of magnetic reversal takes place only in multilayer nanofilms and the heterogeneous multilayer magnetic nanofilms are the base material for creation of spintronic devices. The great advantage of the magnetization reversal of magnetic nanolayers of the spin current is that the mechanism of magnetization reversal is working in the films with perpendicular anisotropy and in the films with in-plane anisotropy. The injection of polarized electrons can also be realized using short electrical pulses. That is why the mechanism of magnetization reversal of the control electrodes spin current is the most appropriate for the management of high-spin current in the elements of spintronics. On the basis of this mechanism, we have realized the high-speed recording of information on the spin carrier and the experimental model memory with three magnetic nanolayers. The data recording in this memory cell is realized using an electric nanosecond pulse.

  18. 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

  19. Controlling spin relaxation with a cavity

    NASA Astrophysics Data System (ADS)

    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.

  20. 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

  1. 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.

  2. Neutron single target spin asymmetries in SIDIS

    SciTech Connect

    Evaristo Cisbani

    2010-04-01

    The experiment E06-010 in Hall A at Jefferson Lab took data between November 2008 and February 2009 to directly measure, for the first time, the pion (and kaon) single "neutron" target-spin asymmetry (SSA) in semi-inclusive DIS from a polarized 3He target. Collins, Sivers (and Pretzelosity) neutron asymmetries are going to be extracted from the measured SSA. Details of the experiment are described together with the preliminary results of the ongoing analysis. Near future Hall A experiments on transverse nucleon spin structure are shorty reviewed.

  3. Strong mechanical driving of a single electron spin

    NASA Astrophysics Data System (ADS)

    Barfuss, A.; Teissier, J.; Neu, E.; Nunnenkamp, A.; Maletinsky, P.

    2015-10-01

    Quantum devices for sensing and computing applications require coherent quantum systems, which can be manipulated in fast and robust ways. Such quantum control is typically achieved using external electromagnetic fields, which drive the systems orbital, charge or spin degrees of freedom. However, most existing approaches require complex and unwieldy gate structures, and with few exceptions are limited to the regime of weak coherent driving. Here, we present a novel approach to coherently drive a single electronic spin using internal strain fields in an integrated quantum device. Specifically, we employ time-varying strain in a diamond cantilever to induce long-lasting, coherent oscillations of an embedded nitrogen-vacancy (NV) centre spin. We perform direct spectroscopy of the phonon-dressed states emerging from this drive and observe hallmarks of the sought-after strong-driving regime, where the spin rotation frequency exceeds the spin splitting. Furthermore, we employ our continuous strain driving to significantly enhance the NVs spin coherence time. Our room-temperature experiments thereby constitute an important step towards strain-driven, integrated quantum devices and open new perspectives to investigate unexplored regimes of strongly driven multilevel systems and exotic spin dynamics in hybrid spin-oscillator devices.

  4. Gigahertz dynamics of a strongly driven single quantum spin.

    PubMed

    Fuchs, G D; Dobrovitski, V V; Toyli, D M; Heremans, F J; Awschalom, D D

    2009-12-11

    Two-level systems are at the core of numerous real-world technologies such as magnetic resonance imaging and atomic clocks. Coherent control of the state is achieved with an oscillating field that drives dynamics at a rate determined by its amplitude. As the strength of the field is increased, a different regime emerges where linear scaling of the manipulation rate breaks down and complex dynamics are expected. By calibrating the spin rotation with an adiabatic passage, we have measured the room-temperature "strong-driving" dynamics of a single nitrogen vacancy center in diamond. With an adiabatic passage to calibrate the spin rotation, we observed dynamics on sub-nanosecond time scales. Contrary to conventional thinking, this breakdown of the rotating wave approximation provides opportunities for time-optimal quantum control of a single spin. PMID:19965386

  5. Single-spin stochastic optical reconstruction microscopy.

    PubMed

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

    2014-10-14

    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

  6. Single-spin stochastic optical reconstruction microscopy

    PubMed Central

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

    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 subdiffraction-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 subdiffraction-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

  7. Single-spin addressing in an atomic Mott insulator.

    PubMed

    Weitenberg, Christof; Endres, Manuel; Sherson, Jacob F; Cheneau, Marc; Schauss, Peter; Fukuhara, Takeshi; Bloch, Immanuel; Kuhr, Stefan

    2011-03-17

    Ultracold atoms in optical lattices provide a versatile tool with which to investigate fundamental properties of quantum many-body systems. In particular, the high degree of control of experimental parameters has allowed the study of many interesting phenomena, such as quantum phase transitions and quantum spin dynamics. Here we demonstrate how such control can be implemented at the most fundamental level of a single spin at a specific site of an optical lattice. Using a tightly focused laser beam together with a microwave field, we were able to flip the spin of individual atoms in a Mott insulator with sub-diffraction-limited resolution, well below the lattice spacing. The Mott insulator provided us with a large two-dimensional array of perfectly arranged atoms, in which we created arbitrary spin patterns by sequentially addressing selected lattice sites after freezing out the atom distribution. We directly monitored the tunnelling quantum dynamics of single atoms in the lattice prepared along a single line, and observed that our addressing scheme leaves the atoms in the motional ground state. The results should enable studies of entropy transport and the quantum dynamics of spin impurities, the implementation of novel cooling schemes, and the engineering of quantum many-body phases and various quantum information processing applications. PMID:21412333

  8. Theory of optical spin control in quantum dot microcavities

    NASA Astrophysics Data System (ADS)

    Smirnov, D. S.; Glazov, M. M.; Ivchenko, E. L.; Lanco, L.

    2015-09-01

    We present a microscopic theory of optical initialization, control, and detection for a single electron spin in a quantum dot embedded into a zero-dimensional microcavity. The strong coupling regime of the trion and the cavity mode is addressed. We demonstrate that efficient spin orientation by a single circularly polarized pulse is possible in relatively weak transverse magnetic fields. The possibilities for spin control by additional circularly polarized pulse are analyzed. Under optimal conditions the Kerr and Faraday rotation angles induced by the spin polarized electron may reach tens of degrees.

  9. Spin-Current Autocorrelations from Single Pure-State Propagation

    NASA Astrophysics Data System (ADS)

    Steinigeweg, Robin; Gemmer, Jochen; Brenig, Wolfram

    2014-03-01

    We demonstrate that the concept of quantum typicality allows for significant progress in the study of real-time spin dynamics and transport in quantum magnets. To this end, we present a numerical analysis of the spin-current autocorrelation function of the antiferromagnetic and anisotropic spin-1/2 Heisenberg chain as inferred from propagating only a single pure state, randomly chosen as a "typical" representative of the statistical ensemble. Comparing with existing time-dependent density-matrix renormalization group data, we show that typicality is fulfilled extremely well, consistent with an error of our approach, which is perfectly under control and vanishes in the thermodynamic limit. In the long-time limit, our results provide for a new benchmark for the enigmatic spin Drude weight, which we obtain from chains as long as L =33 sites, i.e., from Hilbert spaces of dimensions almost O(104) larger than in existing exact-diagonalization studies.

  10. The dynamics and optimal control of spinning spacecraft and movable telescoping appendages, part A. [two axis control with single offset boom

    NASA Technical Reports Server (NTRS)

    Bainum, P. M.; Sellappan, R.

    1977-01-01

    The problem of optimal control with a minimum time criterion as applied to a single boom system for achieving two axis control is discussed. The special case where the initial conditions are such that the system can be driven to the equilibrium state with only a single switching maneuver in the bang-bang optimal sequence is analyzed. The system responses are presented. Application of the linear regulator problem for the optimal control of the telescoping system is extended to consider the effects of measurement and plant noises. The noise uncertainties are included with an application of the estimator - Kalman filter problem. Different schemes for measuring the components of the angular velocity are considered. Analytical results are obtained for special cases, and numerical results are presented for the general case.

  11. Three-dimensional optical manipulation of a single electron spin.

    PubMed

    Geiselmann, Michael; Juan, Mathieu L; Renger, Jan; Say, Jana M; Brown, Louise J; de Abajo, F Javier Garca; Koppens, Frank; Quidant, Romain

    2013-03-01

    Nitrogen vacancy (NV) centres in diamond are promising elemental blocks for quantum optics, spin-based quantum information processing and high-resolution sensing. However, fully exploiting the capabilities of these NV centres requires suitable strategies to accurately manipulate them. Here, we use optical tweezers as a tool to achieve deterministic trapping and three-dimensional spatial manipulation of individual nanodiamonds hosting a single NV spin. Remarkably, we find that the NV axis is nearly fixed inside the trap and can be controlled in situ by adjusting the polarization of the trapping light. By combining this unique spatial and angular control with coherent manipulation of the NV spin and fluorescence lifetime measurements near an integrated photonic system, we demonstrate individual optically trapped NV centres as a novel route for both three-dimensional vectorial magnetometry and sensing of the local density of optical states. PMID:23396312

  12. Nanoscale Spin Seebeck Rectifier: Controlling Thermal Spin Transport across Insulating Magnetic Junctions with Localized Spin

    NASA Astrophysics Data System (ADS)

    Ren, Jie; Fransson, Jonas; Zhu, Jian-Xin

    2014-06-01

    The spin Seebeck effect is studied across a charge insulating magnetic junction, in which thermal-spin conjugate transport is assisted by the exchange interactions between the localized spin in the center and electrons in metallic leads. We show that, in contrast with bulk spin Seebeck effect, the figure of merit of such nanoscale thermal-spin conversion can be infinite, leading to the ideal Carnot efficiency in the linear response regime. We also find that in the nonlinear spin Seebeck transport regime the device possesses the asymmetric and negative differential spin Seebeck effects. In the last, the situations with leaking electron tunneling are also discussed. This nanoscale thermal spin rectifier, by tuning the junction parameters, can act as a spin Seebeck diode, spin Seebeck transistor, and spin Seebeck switch, which could have substantial implications for flexible thermal and information control in molecular spin caloritronics.

  13. Ultrafast optical control of individual quantum dot spin qubits

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  14. Single transverse spin asymmetry of forward neutrons

    NASA Astrophysics Data System (ADS)

    Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivn; Soffer, J.

    2011-12-01

    We calculate the single transverse spin asymmetry AN(t), for inclusive neutron production in pp collisions at forward rapidities relative to the polarized proton in the energy range of RHIC. Absorptive corrections to the pion pole generate a relative phase between the spin-flip and nonflip amplitudes, leading to a transverse spin asymmetry which is found to be far too small to explain the magnitude of AN observed in the PHENIX experiment. A larger contribution, which does not vanish at high energies, comes from the interference of pion and a1-Reggeon exchanges. The unnatural parity of a1 guarantees a substantial phase shift, although the magnitude is strongly suppressed by the smallness of diffractive ?p?a1p cross section. We replace the Regge a1 pole by the Regge cut corresponding to the ?? exchange in the 1+S state. The production of such a state, which we treat as an effective pole a, forms a narrow peak in the 3? invariant mass distribution in diffractive ?p interactions. The cross section is large, so one can assume that this state saturates the spectral function of the axial current and we can determine its coupling to nucleons via the partially conserved axial-vector-current constraint Goldberger-Treiman relation and the second Weinberg sum rule. The numerical results of the parameter-free calculation of AN are in excellent agreement with the PHENIX data.

  15. Coherent coupling of a single spin to microwave cavity photons

    NASA Astrophysics Data System (ADS)

    Viennot, J. J.; Dartiailh, M. C.; Cottet, A.; Kontos, T.

    2015-07-01

    Electron spins and photons are complementary quantum-mechanical objects that can be used to carry, manipulate, and transform quantum information. To combine these resources, it is desirable to achieve the coherent coupling of a single spin to photons stored in a superconducting resonator. Using a circuit design based on a nanoscale spin valve, we coherently hybridize the individual spin and charge states of a double quantum dot while preserving spin coherence. This scheme allows us to achieve spin-photon coupling up to the megahertz range at the single-spin level. The cooperativity is found to reach 2.3, and the spin coherence time is about 60 nanoseconds. We thereby demonstrate a mesoscopic device suitable for nondestructive spin readout and distant spin coupling.

  16. 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.

  17. Spinning solar sail orbit steering via spin rate control

    NASA Astrophysics Data System (ADS)

    Mimasu, Yuya; Yamaguchi, Tomohiro; Matsumoto, Michihiro; Nakamiya, Masaki; Funase, Ryu; Kawaguchi, Jun'ichiro

    2011-12-01

    The orbit of a solar sail can be controlled by changing the attitude of the spacecraft. In this study, we consider the spinning solar power sail IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun), which is managed by Japan Aerospace Exploration Agency (JAXA). The IKAROS attitude, i.e., the direction of its spin-axis, is nominally controlled by the rhumb-line control method. By utilizing the solar radiation torque, however, we are able to change the direction of the spin-axis by only controlling its spin rate. With this spin rate control, we can also control indirectly the solar sail's trajectory. The main objective of this study is to construct the orbit control strategy of the solar sail via the spin-rate control method. We evaluate this strategy in terms of its propellant consumption compared to the rhumb-line control method. Finally, we present the actual flight attitude data of IKAROS and the change of its trajectory.

  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 ?-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. In the three-level system, the exact solution for the driving pulse shows Markovian approximation applies for relatively slow pulses, while non-Markovian dynamics is essential for rapid operation near the cut-off frequency of the waveguide. Secondly, we investigate the dynamic evolution of a single two-level system embedded in the one-dimensional waveguide. It is well known that if the transition frequency of the two-level system is below the cut-off frequency of the one-dimensional waveguide, the spontaneous emission decay will be totally inhibited. However, we find that even the transition frequency is set above the cut-off frequency, the decay is partly suppressed due to the existence of an exciton bound state. When the transition frequency is tuned to the edge of the cut-off frequency, the decay rate is remarkably enhanced. And the Rabi oscillation appears between the discrete bound state and a resonance with finite lifetime. The Non-Markovian spontaneous emission near the band edge reveals the strong coupling between the atom and the continuum. The trapped polariton makes the optical system behave like a cavity without mirror. And the individual quantum dot has shown to be potential to serve as the deterministic single-photon source. Another limit of spin-photon interaction is the weak interaction regime, which often occurs in optical detection of single spins. The interaction between a single spin and a probe device is extremely weak, making measurement difficult. The measurement thus is weak. But disturbance caused by the measurement is also weak. In the weak interaction region, correlations of sequential or continuous weak measurement reveal faithfully dynamics of a single spin. We study the weak measurement of a single spin by a continuouswave light, which is based on the weak Faraday rotation effect. (Abstract shortened by UMI.)

  19. Single spin optically detected magnetic resonance with 60-90 GHz (E-band) microwave resonators

    NASA Astrophysics Data System (ADS)

    Aslam, Nabeel; Pfender, Matthias; Stöhr, Rainer; Neumann, Philipp; Scheffler, Marc; Sumiya, Hitoshi; Abe, Hiroshi; Onoda, Shinobu; Ohshima, Takeshi; Isoya, Junichi; Wrachtrup, Jörg

    2015-06-01

    Magnetic resonance with ensembles of electron spins is commonly performed around 10 GHz, but also at frequencies above 240 GHz and in corresponding magnetic fields of over 9 T. However, experiments with single electron and nuclear spins so far only reach into frequency ranges of several 10 GHz, where existing coplanar waveguide structures for microwave (MW) delivery are compatible with single spin readout techniques (e.g., electrical or optical readout). Here, we explore the frequency range up to 90 GHz, with magnetic fields of up to ≈3 T for single spin magnetic resonance in conjunction with optical spin readout. To this end, we develop MW resonators with optical single spin access. In our case, rectangular 60-90 GHz (E-band) waveguides guarantee low-loss supply of microwaves to the resonators. Three dimensional cavities, as well as coplanar waveguide resonators, enhance MW fields by spatial and spectral confinement with a MW efficiency of 1 . 36 mT / √{ W } . We utilize single nitrogen vacancy (NV) centers as hosts for optically accessible spins and show that their properties regarding optical spin readout known from smaller fields (<0.65 T) are retained up to fields of 3 T. In addition, we demonstrate coherent control of single nuclear spins under these conditions. Furthermore, our results extend the applicable magnetic field range of a single spin magnetic field sensor. Regarding spin based quantum registers, high fields lead to a purer product basis of electron and nuclear spins, which promises improved spin lifetimes. For example, during continuous single-shot readout, the 14N nuclear spin shows second-long longitudinal relaxation times.

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

    PubMed Central

    Luo, Bo; Liu, Juan; L, 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 (?) 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 (?). These results are useful in fabricating and advantaging SMM devices based on spin caloritronics. PMID:24549224

  1. Dynamic control of spin wave spectra using spin-polarized currents

    SciTech Connect

    Wang, Qi; Zhang, Huaiwu Tang, Xiaoli; Bai, Feiming; Zhong, Zhiyong; Fangohr, Hans

    2014-09-15

    We describe a method of controlling the spin wave spectra dynamically in a uniform nanostripe waveguide through spin-polarized currents. A stable periodic magnetization structure is observed when the current flows vertically through the center of nanostripe waveguide. After being excited, the spin wave is transmitted at the sides of the waveguide. Numerical simulations of spin-wave transmission and dispersion curves reveal a single, pronounced band gap. Moreover, the periodic magnetization structure can be turned on and off by the spin-polarized current. The switching process from full rejection to full transmission takes place within less than 3?ns. Thus, this type magnonic waveguide can be utilized for low-dissipation spin wave based filters.

  2. Mechanical control of spin states in spin-1 molecules and the underscreened Kondo effect.

    PubMed

    Parks, J J; Champagne, A R; Costi, T A; Shum, W W; Pasupathy, A N; Neuscamman, E; Flores-Torres, S; Cornaglia, P S; Aligia, A A; Balseiro, C A; Chan, G K-L; Abrua, H D; Ralph, D C

    2010-06-11

    The ability to make electrical contact to single molecules creates opportunities to examine fundamental processes governing electron flow on the smallest possible length scales. We report experiments in which we controllably stretched individual cobalt complexes having spin S = 1, while simultaneously measuring current flow through the molecule. The molecule's spin states and magnetic anisotropy were manipulated in the absence of a magnetic field by modification of the molecular symmetry. This control enabled quantitative studies of the underscreened Kondo effect, in which conduction electrons only partially compensate the molecular spin. Our findings demonstrate a mechanism of spin control in single-molecule devices and establish that they can serve as model systems for making precision tests of correlated-electron theories. PMID:20538943

  3. Gluon saturation effects on single spin asymmetries

    SciTech Connect

    Boer, Danieel

    2007-06-13

    We consider forward pion production in p p collisions at RHIC energies, which probes the so-called Extended Geometric Scaling region. Upon inclusion of small-x effects via an anomalous dimension within the Color Glass Condensate formalism at leading order in {alpha}s, a good description of the cross section as a function of the transverse momentum of the produced pion is obtained. The latter is essential for extractions of the Sivers effect from polarized p p collisions, since it is a sensitive probe of the slope of the cross section. Hence, the presented approach is well suited to extract the Sivers effect from single spin asymmetries in forward pion production at high energies.

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

    PubMed

    Delgado, F; Fernndez-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. PMID:21902416

  5. Optically controlled spins in semiconductor quantum dots

    NASA Astrophysics Data System (ADS)

    Economou, Sophia

    2010-03-01

    Spins in charged semiconductor quantum dots are currently generating much interest, both from a fundamental physics standpoint, as well as for their potential technological relevance. Being naturally a two-level quantum system, each of these spins can encode a bit of quantum information. Optically controlled spins in quantum dots possess several desirable properties: their spin coherence times are long, they allow for all-optical manipulation---which translates into fast logic gates---and their coupling to photons offers a straightforward route to exchange of quantum information between spatially separated sites. Designing the laser fields to achieve the unprecedented amount of control required for quantum information tasks is a challenging goal, towards which there has been recent progress. Special properties of hyperbolic secant optical pulses enabled the design of single qubit rotations, initially developed about the growth axis z [1], and later about an arbitrary direction [2]. Recently we demonstrated our theoretical proposal [1] in an ensemble of InAs/GaAs quantum dots by implementing ultrafast rotations about the z axis by an arbitrary angle [3], with the angle of rotation as a function of the optical detuning in excellent agreement with the theoretical prediction. We also developed two-qubit conditional control in a quantum dot `molecule' using the electron-hole exchange interaction [4]. In addition to its importance in quantum dot-based quantum computation, our two-qubit gate can also play an important role in photonic cluster state generation for measurement-based quantum computing [5]. [1] S. E. Economou, L. J. Sham, Y. Wu, D. S. Steel, Phys. Rev. 74, 205415 (2006) [2] S. E. Economou and T. L. Reinecke, Phys. Rev. Lett., 99, 217401 (2007) [3] A. Greilich, S. E. Economou et al, Nature Phys. 5, 262 (2009) [4] S. E. Economou and T. L. Reinecke, Phys. Rev. B, 78, 115306 (2008) [5] S. E. Economou, N. H. Lindner, and T. Rudolph, in preparation

  6. Controlling the quantum dynamics of a mesoscopic spin bath in diamond

    PubMed Central

    de Lange, Gijs; van der Sar, Toeno; Blok, Machiel; Wang, Zhi-Hui; Dobrovitski, Viatcheslav; Hanson, Ronald

    2012-01-01

    Understanding and mitigating decoherence is a key challenge for quantum science and technology. The main source of decoherence for solid-state spin systems is the uncontrolled spin bath environment. Here, we demonstrate quantum control of a mesoscopic spin bath in diamond at room temperature that is composed of electron spins of substitutional nitrogen impurities. The resulting spin bath dynamics are probed using a single nitrogen-vacancy (NV) centre electron spin as a magnetic field sensor. We exploit the spin bath control to dynamically suppress dephasing of the NV spin by the spin bath. Furthermore, by combining spin bath control with dynamical decoupling, we directly measure the coherence and temporal correlations of different groups of bath spins. These results uncover a new arena for fundamental studies on decoherence and enable novel avenues for spin-based magnetometry and quantum information processing. PMID:22536480

  7. Controlling the quantum dynamics of a mesoscopic spin bath in diamond

    NASA Astrophysics Data System (ADS)

    de Lange, Gijs; van der Sar, Toeno; Blok, Machiel; Wang, Zhi-Hui; Dobrovitski, Viatcheslav; Hanson, Ronald

    2012-04-01

    Understanding and mitigating decoherence is a key challenge for quantum science and technology. The main source of decoherence for solid-state spin systems is the uncontrolled spin bath environment. Here, we demonstrate quantum control of a mesoscopic spin bath in diamond at room temperature that is composed of electron spins of substitutional nitrogen impurities. The resulting spin bath dynamics are probed using a single nitrogen-vacancy (NV) centre electron spin as a magnetic field sensor. We exploit the spin bath control to dynamically suppress dephasing of the NV spin by the spin bath. Furthermore, by combining spin bath control with dynamical decoupling, we directly measure the coherence and temporal correlations of different groups of bath spins. These results uncover a new arena for fundamental studies on decoherence and enable novel avenues for spin-based magnetometry and quantum information processing.

  8. 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.

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

    PubMed Central

    Arnold, Christophe; Demory, Justin; Loo, Vivien; Lematre, Aristide; Sagnes, Isabelle; Glazov, Mikhal; Krebs, Olivier; Voisin, Paul; Senellart, Pascale; Lanco, Loc

    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 spinphoton coupling. Here we report the enhancement by three orders of magnitude of the spinphoton 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

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

    PubMed

    Arnold, Christophe; Demory, Justin; Loo, Vivien; Lematre, Aristide; Sagnes, Isabelle; Glazov, Mikhal; Krebs, Olivier; Voisin, Paul; Senellart, Pascale; Lanco, Loc

    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

  11. Spin coherence in a Mn3 single-molecule magnet

    NASA Astrophysics Data System (ADS)

    Abeywardana, Chathuranga; Mowson, Andrew M.; Christou, George; Takahashi, Susumu

    2016-01-01

    Spin coherence in single crystals of the spin S = 6 single-molecule magnet (SMM) [Mn3O(O2CEt)3(mpko)3]+ (abbreviated Mn3) has been investigated using 230 GHz electron paramagnetic resonance spectroscopy. Coherence in Mn3 was uncovered by significantly suppressing dipolar contribution to the decoherence with complete spin polarization of Mn3 SMMs. The temperature dependence of spin decoherence time (T2) revealed that the dipolar decoherence is the dominant source of decoherence in Mn3 and T2 can be extended up to 267 ns by quenching the dipolar decoherence.

  12. Spin noise spectroscopy in semiconductors: from a billion down to single spins

    NASA Astrophysics Data System (ADS)

    Hbner, J.; Dahbashi, R.; Berski, F.; Wiegand, J.; Kuhn, H.; Lonnemann, J.; Oestreich, M.

    2014-08-01

    Spin noise spectroscopy in semiconductors has matured during the past nine years into a versatile and well developed technique being capable to unveil the intrinsic and unaltered spin dynamics in a wide range of semiconductor systems. Originating from atom and quantum optics as a potential true quantum non-demolition measurement technique, SNS is capable of unearthing the intricate dynamics of free or localized electron and hole spins in semiconductors being eventually coupled to the nuclear spin bath as well. In this contribution, we review shortly the major steps which inspired the success of spin noise spectroscopy in semiconductors and present the most recent extensions into the low-invasive detection regime of the spin dynamics for the two extreme limits of very high and extremely low rates of spin decoherence, respectively. On the one hand, merging ultrafast laser spectroscopy with spin noise spectroscopy enables the detection of spin noise with picosecond resolution, i.e., with THz bandwidths yielding access to otherwise concealed microscopic electronic processes. On the other hand, we present very high sensitivity SNS being capable to measure the extremely long spin coherence of single holes enclosed in individual quantum dots venturing a step forward towards true optical quantum non-demolition experiments in semiconductors. In addition, higher-order spin noise statistics of, e.g., single charges can give information beyond the linear response regime governed by the fundamental fluctuationdissipation theorem and thereby possibly shed some light on the nested coupling between electronic and nuclear spins.

  13. 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.

  14. K-band single-chip electron spin resonance detector

    NASA Astrophysics Data System (ADS)

    Anders, Jens; Angerhofer, Alexander; Boero, Giovanni

    2012-04-01

    We report on the design, fabrication, and characterization of an integrated detector for electron spin resonance spectroscopy operating at 27 GHz. The microsystem, consisting of an LC-oscillator and a frequency division module, is integrated onto a single silicon chip using a conventional complementary metal-oxide-semiconductor technology. The achieved room temperature spin sensitivity is about 108 spins/G Hz1/2, with a sensitive volume of about (100 ?m)3. Operation at 77 K is also demonstrated.

  15. 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.

  16. 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.

  17. 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.

  18. Detecting and Polarizing Nuclear Spins with Double Resonance on a Single Electron Spin

    NASA Astrophysics Data System (ADS)

    London, P.; Scheuer, J.; Cai, J.-M.; Schwarz, I.; Retzker, A.; Plenio, M. B.; Katagiri, M.; Teraji, T.; Koizumi, S.; Isoya, J.; Fischer, R.; McGuinness, L. P.; Naydenov, B.; Jelezko, F.

    2013-08-01

    We report the detection and polarization of nuclear spins in diamond at room temperature by using a single nitrogen-vacancy (NV) center. We use Hartmann-Hahn double resonance to coherently enhance the signal from a single nuclear spin while decoupling from the noisy spin bath, which otherwise limits the detection sensitivity. As a proof of principle, we (i) observe coherent oscillations between the NV center and a weakly coupled nuclear spin and (ii) demonstrate nuclear-bath cooling, which prolongs the coherence time of the NV sensor by more than a factor of 5. Our results provide a route to nanometer scale magnetic resonance imaging and novel quantum information processing protocols.

  19. Electronic read-out of a single nuclear spin using a molecular spin transistor

    NASA Astrophysics Data System (ADS)

    Balestro, Franck

    2013-03-01

    Thanks to recent advances of nanofabrication techniques, molecular electronics devices can address today the ultimate probing of electronic transport flowing through a single molecule. Not only this electronic current can show signatures of the molecular quantum levels but it can also detect the magnetic state of the molecule. As a consequence, an entirely novel research field called molecular spintronics in which quantum magnetism of molecular systems can be interfaced to nanoelectronics is now emerging. One of the recent challenges of this field was to probe by this current, not the only spin state of an electron, but the state of a single nuclear spin. Such an achievement was experimentally unimaginable a few years ago. Indeed, the magnetic signal carried by a single nuclear spin is a thousand times less than that of a single electron spin... Using a Single Molecular Magnet (TbPc2) as a molecular spin transistor in a three terminals configuration, the experiment consists in measuring the current changes when ones sweep the external magnetic field applied to the molecule. When the magnetic spin of the molecule changes its quantum state, a change of current is recorded. Because of the well-defined relationship that exists between the electron spin and nuclear spin carried by the nuclei of the Terbium atom, it is possible to perform the electronic read-out of the electronic spin state which, in turn give information on the state of a single nuclear spin. Application of this effect for quantum information manipulation and storage can be envisioned, as the observation of energy level lifetimes on the order of tens of seconds opens the way to coherent manipulations of a single nuclear spin. In collaboration with R. Vincent, Neel Institut - CNRS - UJF; S. Klyatskaya, Institut of Nanotechnology - KIT; M. Ruben, Institut of Nanotechnology - KIT; and W. Wernsdorfer, Neel Institut - CNRS - UJF.

  20. Controllable spin entanglement production in a quantum spin Hall ring

    NASA Astrophysics Data System (ADS)

    Strm, Anders; Johannesson, Henrik; Recher, Patrik

    2015-06-01

    We study the entanglement production in a quantum spin Hall ring geometry where electrons of opposite spins are emitted in pairs from a source and collected in two different detectors. Postselection of coincidence detector events gives rise to entanglement in the system, measurable through correlations between the outcomes in the detectors. We have chosen a geometry such that the entanglement depends on the dynamical phases picked up by the edge states as they move around the ring. In turn, the dependence of the phases on gate potential and Rashba interaction allows for a precise electrical control of the entanglement production in the ring.

  1. 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

    2015-01-01

    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. PMID:26151881

  2. 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.

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

    PubMed

    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, Jrg; Scholten, Robert E; Mulvaney, Paul; Hollenberg, Lloyd

    2013-07-01

    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 Hz(1/2)], opens a pathway for in situ nanoscale detection of dynamical processes in biology. PMID:23776230

  4. Nanoscale spin rectifiers controlled by the Stark effect

    NASA Astrophysics Data System (ADS)

    Rossella, Francesco; Bertoni, Andrea; Ercolani, Daniele; Rontani, Massimo; Sorba, Lucia; Beltram, Fabio; Roddaro, Stefano

    2014-12-01

    The control of orbitals and spin states of single electrons is a key ingredient for quantum information processing and novel detection schemes and is, more generally, of great relevance for spintronics. Coulomb and spin blockade in double quantum dots enable advanced single-spin operations that would be available even for room-temperature applications with sufficiently small devices. To date, however, spin operations in double quantum dots have typically been observed at sub-kelvin temperatures, a key reason being that it is very challenging to scale a double quantum dot system while retaining independent field-effect control of individual dots. Here, we show that the quantum-confined Stark effect allows two dots only 5?nm apart to be independently addressed without the requirement for aligned nanometre-sized local gating. We thus demonstrate a scalable method to fully control a double quantum dot device, regardless of its physical size. In the present implementation we present InAs/InP nanowire double quantum dots that display an experimentally detectable spin blockade up to 10?K. We also report and discuss an unexpected re-entrant spin blockade lifting as a function of the magnetic field intensity.

  5. Nanoscale spin rectifiers controlled by the Stark effect.

    PubMed

    Rossella, Francesco; Bertoni, Andrea; Ercolani, Daniele; Rontani, Massimo; Sorba, Lucia; Beltram, Fabio; Roddaro, Stefano

    2014-12-01

    The control of orbitals and spin states of single electrons is a key ingredient for quantum information processing and novel detection schemes and is, more generally, of great relevance for spintronics. Coulomb and spin blockade in double quantum dots enable advanced single-spin operations that would be available even for room-temperature applications with sufficiently small devices. To date, however, spin operations in double quantum dots have typically been observed at sub-kelvin temperatures, a key reason being that it is very challenging to scale a double quantum dot system while retaining independent field-effect control of individual dots. Here, we show that the quantum-confined Stark effect allows two dots only 5?nm apart to be independently addressed without the requirement for aligned nanometre-sized local gating. We thus demonstrate a scalable method to fully control a double quantum dot device, regardless of its physical size. In the present implementation we present InAs/InP nanowire double quantum dots that display an experimentally detectable spin blockade up to 10?K. We also report and discuss an unexpected re-entrant spin blockade lifting as a function of the magnetic field intensity. PMID:25383514

  6. Coherent single-spin source based on topological insulators

    NASA Astrophysics Data System (ADS)

    Xing, Yanxia; Yang, Zhong-Liu; Sun, Qing-Feng; Wang, Jian

    2015-03-01

    We report on the injection of quantized pure spin current into quantum conductors. In particular, we propose an on-demand single-spin source generated by periodically varying the gate voltages of two quantum dots that are connected to a two-dimensional topological insulator via tunneling barriers. Due to the nature of the helical states of the topological insulator, one or several spin pairs can be pumped out per cycle giving rise to a pure quantized alternating spin current. Depending on the phase difference between two gate voltages, this device can serve as an on-demand single-spin emitter or single-charge emitter. Again, due to the helicity of the topological insulator, the single-spin emitter or charge emitter is dissipationless and immune to disorder. The proposed single-spin emitter can be an important building block of future spintronic devices. We gratefully acknowledge the financial support from from NSF-China under Grant (Nos. 11174032 and 11374246), NBRP of China (2012CB921303), and a RGC Grant (HKU 705212P) from the Government of HKSAR.

  7. Radio-Frequency Magnetometry Using a Single Electron Spin

    NASA Astrophysics Data System (ADS)

    Loretz, M.; Rosskopf, T.; Degen, C. L.

    2013-01-01

    We experimentally demonstrate a simple and robust protocol for the detection of weak radio-frequency magnetic fields using a single electron spin in diamond. Our method relies on spin locking, where the Rabi frequency of the spin is adjusted to match the MHz signal frequency. In a proof-of-principle experiment we detect a 7.5 MHz magnetic probe field of 40nT amplitude with <10kHz spectral resolution. Rotating-frame magnetometry may provide a direct and sensitive route to high-resolution spectroscopy of nanoscale nuclear spin signals.

  8. 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 leptonnucleon scattering, in nucleonnucleon scattering, and in inclusive leptonnucleon 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.

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

    DOE PAGESBeta

    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

  10. Quark spin distribution and quark-antiquark annihilation in single-spin hadron-hadron collisions

    SciTech Connect

    Boros, C.; Zuo-tang, L.; Ta-chung, M. )

    1993-03-22

    We show that quark-antiquark annihilation processes in single-spin inclusive production experiments can yield useful information on hadron spin structure in general, and provide crucial tests for the existence of orbiting valence quarks in particular. There are several experimental indications and theoretical arguments for the existence of such orbital motion inside polarized protons or antiprotons. Simple relations between quark-spin distributions and left-right asymmetries in such production processes can be given, and quantitative predictions can be made.

  11. Manipulating Single Spins in Quantum Dots Coupled to Ferromagnetic Leads

    NASA Astrophysics Data System (ADS)

    König, Jürgen; Braun, Matthias; Martinek, Jan

    We discuss the possibility to generate, manipulate, and probe single spins in single-level quantum dots coupled to ferromagnetic leads. The spin-polarized currents flowing between dot and leads lead to a non-equilibrium spin accumulation, i.e., a finite polarization of the dot spin. Both the magnitude and the direction of the dot's spin polarization depends on the magnetic properties of leads and their coupling to the dot. They can be, furthermore, manipulated by either an externally applied magnetic field or an intrinsically present exchange field that arises due to the tunnel coupling of the strongly-interacting quantum-dot states to spin-polarized leads. The exchange field can be tuned by both the gate and bias voltage, which, therefore, provide convenient handles to manipulate the quantum-dot spin. Since the transmission through the quantum-dot spin valve sensitively depends on the state of the quantum-dot spin, all the dynamics of the latter is reflected in the transport properties of the device.

  12. Nanometer-scale probing of spin waves using single electron spins

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    We have developed a new approach to exploring magnetic excitations in correlated-electron systems, based on single electronic spins in atom-like defects diamond known as nitrogen-vacancy (NV) color centers. We demonstrate the power of this approach by detecting spin-wave excitations in a ferromagnetic microdisc with nanoscale spatial sensitivity over a broad range of frequencies and magnetic fields. We show how spin-wave resonances can be exploited for on-chip amplification of microwave magnetic fields, allowing strongly increased spin manipulation rates and single-spin magnetometry with enhanced sensitivity. Finally, we show the possibility to detect the magnetic spin noise produced by a thin (~ 30 nm) layer of a patterned ferromagnet. For the interpretation of our results, we develop a general framework describing single-spin stray field detection in terms of a filter function sensitive mostly to spin fluctuations with wavevector ~ 1 / d , where d is the NV-ferromagnet distance. Our results pave the way towards quantitative and non-perturbative detection of spectral properties in nanomagnets, establishing NV center magnetometry as an emergent probe of collective spin dynamics in condensed matter.

  13. 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

  14. Optical control of donor spin qubits in silicon

    NASA Astrophysics Data System (ADS)

    Gullans, M. J.; Taylor, J. M.

    2015-11-01

    We show how to achieve optical, spin-selective transitions from the ground state to excited orbital states of group-V donors (P, As, Sb, and Bi) in silicon. We consider two approaches based on either resonant, far-infrared (IR) transitions of the neutral donor or resonant, near-IR excitonic transitions. For far-IR light, we calculate the dipole matrix elements between the valley-orbit and spin-orbit split states for all the group-V donors using effective mass theory. We then calculate the maximum rate and amount of electron-nuclear spin-polarization achievable through optical pumping with circularly polarized light. We find this approach is most promising for Bi donors due to their large spin-orbit and valley-orbit interactions. Using near-IR light, spin-selective excitation is possible for all the donors by driving a two-photon ? transition from the ground state to higher orbitals with even parity. We show that externally applied electric fields or strain allow similar, spin-selective ? transition to odd-parity excited states. We anticipate these results will be useful for future spectroscopic investigations of donors, quantum control and state preparation of donor spin qubits, and for developing a coherent interface between donor spin qubits and single photons.

  15. Light-controlled spin filtering in bacteriorhodopsin.

    PubMed

    Einati, Hila; Mishra, Debabrata; Friedman, Noga; Sheves, Mordechai; Naaman, Ron

    2015-02-11

    The role of the electron spin in chemistry and biology has received much attention recently owing to to the possible electromagnetic field effects on living organisms and the prospect of using molecules in the emerging field of spintronics. Recently the chiral-induced spin selectivity effect was observed by electron transmission through organic molecules. In the present study, we demonstrated the ability to control the spin filtering of electrons by light transmitted through purple membranes containing bacteriorhodopsin (bR) and its D96N mutant. The spin-dependent electrochemical cyclic voltammetry (CV) and chronoamperometric measurements were performed with the membranes deposited on nickel substrates. High spin-dependent electron transmission through the membranes was observed; however, after the samples were illuminated by 532 nm light, the spin filtering in the D96N mutant was dramatically reduced whereas the light did not have any effect on the wild-type bR. Beyond demonstrating spin-dependent electron transmission, this work also provides an interesting insight into the relationship between the structure of proteins and spin filtering by conducting electrons. PMID:25621438

  16. Light-Controlled Spin Filtering in Bacteriorhodopsin

    PubMed Central

    2015-01-01

    The role of the electron spin in chemistry and biology has received much attention recently owing to to the possible electromagnetic field effects on living organisms and the prospect of using molecules in the emerging field of spintronics. Recently the chiral-induced spin selectivity effect was observed by electron transmission through organic molecules. In the present study, we demonstrated the ability to control the spin filtering of electrons by light transmitted through purple membranes containing bacteriorhodopsin (bR) and its D96N mutant. The spin-dependent electrochemical cyclic voltammetry (CV) and chronoamperometric measurements were performed with the membranes deposited on nickel substrates. High spin-dependent electron transmission through the membranes was observed; however, after the samples were illuminated by 532 nm light, the spin filtering in the D96N mutant was dramatically reduced whereas the light did not have any effect on the wild-type bR. Beyond demonstrating spin-dependent electron transmission, this work also provides an interesting insight into the relationship between the structure of proteins and spin filtering by conducting electrons. PMID:25621438

  17. Nuclear magnetic resonance spectroscopy with single spin sensitivity.

    PubMed

    Mller, C; Kong, X; Cai, J-M; Melentijevi?, 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

    2014-01-01

    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. PMID:25146503

  18. 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

  19. Coherent properties of single rare-earth spin qubits

    NASA Astrophysics Data System (ADS)

    Siyushev, P.; Xia, K.; Reuter, R.; Jamali, M.; Zhao, N.; Yang, N.; Duan, C.; Kukharchyk, N.; Wieck, A. D.; Kolesov, R.; Wrachtrup, J.

    2014-05-01

    Rare-earth-doped crystals are excellent hardware for quantum storage of photons. Additional functionality of these materials is added by their waveguiding properties allowing for on-chip photonic networks. However, detection and coherent properties of rare-earth single-spin qubits have not been demonstrated so far. Here we present experimental results on high-fidelity optical initialization, effcient coherent manipulation and optical readout of a single-electron spin of Ce3+ ion in a yttrium aluminium garnet crystal. Under dynamic decoupling, spin coherence lifetime reaches T2=2?ms and is almost limited by the measured spin-lattice relaxation time T1=4.5?ms. Strong hyperfine coupling to aluminium nuclear spins suggests that cerium electron spins can be exploited as an interface between photons and long-lived nuclear spin memory. Combined with high brightness of Ce3+ emission and a possibility of creating photonic circuits out of the host material, this makes cerium spins an interesting option for integrated quantum photonics.

  20. Coherent properties of single rare-earth spin qubits.

    PubMed

    Siyushev, P; Xia, K; Reuter, R; Jamali, M; Zhao, N; Yang, N; Duan, C; Kukharchyk, N; Wieck, A D; Kolesov, R; Wrachtrup, J

    2014-01-01

    Rare-earth-doped crystals are excellent hardware for quantum storage of photons. Additional functionality of these materials is added by their waveguiding properties allowing for on-chip photonic networks. However, detection and coherent properties of rare-earth single-spin qubits have not been demonstrated so far. Here we present experimental results on high-fidelity optical initialization, efficient coherent manipulation and optical readout of a single-electron spin of Ce(3+) ion in a yttrium aluminium garnet crystal. Under dynamic decoupling, spin coherence lifetime reaches T2 = 2 ms and is almost limited by the measured spin-lattice relaxation time T1 = 4.5 ms. Strong hyperfine coupling to aluminium nuclear spins suggests that cerium electron spins can be exploited as an interface between photons and long-lived nuclear spin memory. Combined with high brightness of Ce(3+) emission and a possibility of creating photonic circuits out of the host material, this makes cerium spins an interesting option for integrated quantum photonics. PMID:24826968

  1. Efficient Readout of a Single Spin State in Diamond via Spin-to-Charge Conversion

    NASA Astrophysics Data System (ADS)

    Shields, B. J.; Unterreithmeier, Q. P.; de Leon, N. P.; Park, H.; Lukin, M. D.

    2015-04-01

    Efficient readout of individual electronic spins associated with atomlike impurities in the solid state is essential for applications in quantum information processing and quantum metrology. We demonstrate a new method for efficient spin readout of nitrogen-vacancy (NV) centers in diamond. The method is based on conversion of the electronic spin state of the NV to a charge-state distribution, followed by single-shot readout of the charge state. Conversion is achieved through a spin-dependent photoionization process in diamond at room temperature. Using NVs in nanofabricated diamond beams, we demonstrate that the resulting spin readout noise is within a factor of 3 of the spin projection noise level. Applications of this technique for nanoscale magnetic sensing are discussed.

  2. Efficient readout of a single spin state in diamond via spin-to-charge conversion.

    PubMed

    Shields, B J; Unterreithmeier, Q P; de Leon, N P; Park, H; Lukin, M D

    2015-04-01

    Efficient readout of individual electronic spins associated with atomlike impurities in the solid state is essential for applications in quantum information processing and quantum metrology. We demonstrate a new method for efficient spin readout of nitrogen-vacancy (NV) centers in diamond. The method is based on conversion of the electronic spin state of the NV to a charge-state distribution, followed by single-shot readout of the charge state. Conversion is achieved through a spin-dependent photoionization process in diamond at room temperature. Using NVs in nanofabricated diamond beams, we demonstrate that the resulting spin readout noise is within a factor of 3 of the spin projection noise level. Applications of this technique for nanoscale magnetic sensing are discussed. PMID:25884129

  3. 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.

  4. Single spin detection by magnetic resonance force microscopy.

    PubMed

    Rugar, D; Budakian, R; Mamin, H J; Chui, B W

    2004-07-15

    Magnetic resonance imaging (MRI) is well known as a powerful technique for visualizing subsurface structures with three-dimensional spatial resolution. Pushing the resolution below 1 micro m remains a major challenge, however, owing to the sensitivity limitations of conventional inductive detection techniques. Currently, the smallest volume elements in an image must contain at least 10(12) nuclear spins for MRI-based microscopy, or 10(7) electron spins for electron spin resonance microscopy. Magnetic resonance force microscopy (MRFM) was proposed as a means to improve detection sensitivity to the single-spin level, and thus enable three-dimensional imaging of macromolecules (for example, proteins) with atomic resolution. MRFM has also been proposed as a qubit readout device for spin-based quantum computers. Here we report the detection of an individual electron spin by MRFM. A spatial resolution of 25 nm in one dimension was obtained for an unpaired spin in silicon dioxide. The measured signal is consistent with a model in which the spin is aligned parallel or anti-parallel to the effective field, with a rotating-frame relaxation time of 760 ms. The long relaxation time suggests that the state of an individual spin can be monitored for extended periods of time, even while subjected to a complex set of manipulations that are part of the MRFM measurement protocol. PMID:15254532

  5. Electric control of the spin Hall effect by intervalley transitions

    NASA Astrophysics Data System (ADS)

    Okamoto, N.; Kurebayashi, H.; Trypiniotis, T.; Farrer, I.; Ritchie, D. A.; Saitoh, E.; Sinova, J.; Maek, J.; Jungwirth, T.; Barnes, C. H. W.

    2014-10-01

    Controlling spin-related material properties by electronic means is a key step towards future spintronic technologies. The spin Hall effect (SHE) has become increasingly important for generating, detecting and using spin currents, but its strengthquantified in terms of the SHE angleis ultimately fixed by the magnitude of the spin-orbit coupling (SOC) present for any given material system. However, if the electrons generating the SHE can be controlled by populating different areas (valleys) of the electronic structure with different SOC characteristic the SHE angle can be tuned directly within a single sample. Here we report the manipulation of the SHE in bulk GaAs at room temperature by means of an electrical intervalley transition induced in the conduction band. The spin Hall angle was determined by measuring an electromotive force driven by photoexcited spin-polarized electrons drifting through GaAs Hall bars. By controlling electron populations in different (? and L) valleys, we manipulated the angle from 0.0005 to 0.02. This change by a factor of 40 is unprecedented in GaAs and the highest value achieved is comparable to that of the heavy metal Pt.

  6. Electric control of the spin Hall effect by intervalley transitions.

    PubMed

    Okamoto, N; Kurebayashi, H; Trypiniotis, T; Farrer, I; Ritchie, D A; Saitoh, E; Sinova, J; Maek, J; Jungwirth, T; Barnes, C H W

    2014-10-01

    Controlling spin-related material properties by electronic means is a key step towards future spintronic technologies. The spin Hall effect (SHE) has become increasingly important for generating, detecting and using spin currents, but its strength--quantified in terms of the SHE angle--is ultimately fixed by the magnitude of the spin-orbit coupling (SOC) present for any given material system. However, if the electrons generating the SHE can be controlled by populating different areas (valleys) of the electronic structure with different SOC characteristic the SHE angle can be tuned directly within a single sample. Here we report the manipulation of the SHE in bulk GaAs at room temperature by means of an electrical intervalley transition induced in the conduction band. The spin Hall angle was determined by measuring an electromotive force driven by photoexcited spin-polarized electrons drifting through GaAs Hall bars. By controlling electron populations in different (? and L) valleys, we manipulated the angle from 0.0005 to 0.02. This change by a factor of 40 is unprecedented in GaAs and the highest value achieved is comparable to that of the heavy metal Pt. PMID:25108612

  7. High-fidelity spin entanglement using optimal control

    NASA Astrophysics Data System (ADS)

    Dolde, Florian; Bergholm, Ville; Wang, Ya; Jakobi, Ingmar; Naydenov, Boris; Pezzagna, Sbastien; Meijer, Jan; Jelezko, Fedor; Neumann, Philipp; Schulte-Herbrggen, Thomas; Biamonte, Jacob; Wrachtrup, Jrg

    2014-02-01

    Precise control of quantum systems is of fundamental importance in quantum information processing, quantum metrology and high-resolution spectroscopy. When scaling up quantum registers, several challenges arise: individual addressing of qubits while suppressing cross-talk, entangling distant nodes and decoupling unwanted interactions. Here we experimentally demonstrate optimal control of a prototype spin qubit system consisting of two proximal nitrogen-vacancy centres in diamond. Using engineered microwave pulses, we demonstrate single electron spin operations with a fidelity F?0.99. With additional dynamical decoupling techniques, we further realize high-quality, on-demand entangled states between two electron spins with F>0.82, mostly limited by the coherence time and imperfect initialization. Crosstalk in a crowded spectrum and unwanted dipolar couplings are simultaneously eliminated to a high extent. Finally, by high-fidelity entanglement swapping to nuclear spin quantum memory, we demonstrate nuclear spin entanglement over a length scale of 25?nm. This experiment underlines the importance of optimal control for scalable room temperature spin-based quantum information devices.

  8. Cryogenic single-chip electron spin resonance detector

    NASA Astrophysics Data System (ADS)

    Gualco, Gabriele; Anders, Jens; Sienkiewicz, Andrzej; Alberti, Stefano; Forr, Lszl; Boero, Giovanni

    2014-10-01

    We report on the design and characterization of a single-chip electron spin resonance detector, operating at a frequency of about 20 GHz and in a temperature range extending at least from 300 K down to 4 K. The detector consists of an LC oscillator formed by a 200 ?m diameter single turn aluminum planar coil, a metal-oxide-metal capacitor, and two metal-oxide-semiconductor field effect transistors used as negative resistance network. At 300 K, the oscillator has a frequency noise of 20 Hz/Hz1/2 at 100 kHz offset from the 20 GHz carrier. At 4 K, the frequency noise is about 1 Hz/Hz1/2 at 10 kHz offset. The spin sensitivity measured with a sample of DPPH is 108 spins/Hz1/2 at 300 K and down to 106 spins/Hz1/2 at 4 K.

  9. Observation of spin flips with a single trapped proton.

    PubMed

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

    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. PMID:21770638

  10. 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.

  11. Observation of Spin Flips with a Single Trapped Proton

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

    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.

  12. Switching of a coupled spin pair in a single-molecule junction.

    PubMed

    Wagner, Stefan; Kisslinger, Ferdinand; Ballmann, Stefan; Schramm, Frank; Chandrasekar, Rajadurai; Bodenstein, Tilmann; Fuhr, Olaf; Secker, Daniel; Fink, Karin; Ruben, Mario; Weber, Heiko B

    2013-08-01

    Single-molecule spintronics investigates electron transport through magnetic molecules that have an internal spin degree of freedom. To understand and control these individual molecules it is important to read their spin state. For unpaired spins, the Kondo effect has been observed as a low-temperature anomaly at small voltages. Here, we show that a coupled spin pair in a single magnetic molecule can be detected and that a bias voltage can be used to switch between two states of the molecule. In particular, we use the mechanically controlled break-junction technique to measure electronic transport through a single-molecule junction containing two coupled spin centres that are confined on two Co(2+) ions. Spin-orbit configuration interaction methods are used to calculate the combined spin system, where the ground state is found to be a pseudo-singlet and the first excitations behave as a pseudo-triplet. Experimentally, these states can be assigned to the absence and occurrence of a Kondo-like zero-bias anomaly in the low-temperature conductance data, respectively. By applying finite bias, we can repeatedly switch between the pseudo-singlet state and the pseudo-triplet state. PMID:23851359

  13. High spin rate magnetic controller for nanosatellites

    NASA Astrophysics Data System (ADS)

    Slavinskis, A.; Kvell, U.; Kulu, E.; Snter, I.; Kuuste, H.; Ltt, 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. Hall magnetometry of micromagnets for single-electron spin qubits

    NASA Astrophysics Data System (ADS)

    Lachance-Quirion, Dany; Camirand Lemyre, Julien; Bergeron, Laurent; Pioro-Ladrire, Michel

    2015-03-01

    The coherence time of a single-electron spin can reach tens of milliseconds when placed in the right environment. The electric-dipole interaction between such a single spin and an electric field can be engineered by the inhomogeneous magnetic field of a micromagnet. This effective spin-orbit interaction can be used to manipulate the spin through electric-dipole spin resonance, but also to couple a single spin to the electric field of a microwave cavity in the circuit QED architecture. We selected the material and improved the shape of the micromagnet in order to maximize magnetic field gradients and remanence. We perform Hall magnetometry of those improved micromagnets using Hall bars electrostatically defined in an AlGaAs/GaAs two-dimensional electron gas. The gate-voltage dependent width of the Hall bar enables us to map the averaged magnetic field of the micromagnet, which validates simulations of the inhomogeneous magnetic field profile created by the magnet. We can therefore deduce that our micromagnets can produce magnetic field differences over 200 nm of more than 200 mT.

  15. Single-spin observables and orbital structures in hadronic distributions

    NASA Astrophysics Data System (ADS)

    Sivers, Dennis

    2006-11-01

    Single-spin observables in scattering processes (either analyzing powers or polarizations) are highly constrained by rotational invariance and finite symmetries. For example, it is possible to demonstrate that all single-spin observables are odd under the finite transformation O=PAτ where P is parity and Aτ is a finite symmetry that can be designated “artificial time reversal”. The operators P, O and Aτ all have eigenvalues ±1 so that all single-spin observables can be classified into two distinct categories: (1) P-odd and Aτ-even, (2) P-even and Aτ-odd. Within the light-quark sector of the standard model, P-odd observables are generated from pointlike electroweak processes while Aτ-odd observables (neglecting quark mass parameters) come from dynamic spin-orbit correlations within hadrons or within larger composite systems, such as nuclei. The effects of Aτ-odd dynamics can be inserted into transverse-momentum dependent constituent distribution functions and, in this paper, we construct the contribution from an orbital quark to the Aτ-odd quark parton distribution ΔNGq/p↑front(x,kTN;μ2). Using this distribution, we examine the crucial role of initial- and final-state interactions in the observation of the scattering asymmetries in different hard-scattering processes. This construction provides a geometrical and dynamical interpretation of the Collins conjugation relation between single-spin asymmetries in semi-inclusive deep inelastic scattering and the asymmetries in Drell-Yan production. Finally, our construction allows us to display a significant difference between the calculation of a spin asymmetry generated by a hard-scattering mechanism involving color-singlet exchange (such as a photon) and a calculation of an asymmetry with a hard-scattering exchange involving gluons. This leads to an appreciation of the process-dependence inherent in measurements of single-spin observables.

  16. Spin reorientation transition in dysprosium-samarium orthoferrite single crystals

    NASA Astrophysics Data System (ADS)

    Zhao, Weiyao; Cao, Shixun; Huang, Ruoxiang; Cao, Yiming; Xu, Kai; Kang, Baojuan; Zhang, Jincang; Ren, Wei

    2015-03-01

    We report the control of spin reorientation (SR) transition in perovskite D y1 -xS mxFe O3 , a whole family of single crystals grown by an optical floating zone method from x =0 to 1 with an interval of 0.1. Powder x-ray diffractions and Rietveld refinements indicate that lattice parameters a and c increase linearly with Sm doping concentration, whereas b keeps a constant. Temperature dependence of the magnetizations under zero-field-cooling (ZFC) and field-cooling (FC) processes are studied in detail. 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 the FC during cooling (FCC) process bifurcate from and then jump back to that of the ZFC and FC warming process in single crystals when x =0.5 -0.9 , suggesting complicated 4 f -3 d electron interactions among D y3 + -S m3 +,D y3 + -F e3 + , and S m3 + -F e3 + sublattices of diverse magnetic configurations. The magnetic properties from the doping effect on SR transition temperature in these single crystals might be useful in the material physics and device design applications.

  17. Detecting and polarizing nuclear spins with double resonance on a single electron spin.

    PubMed

    London, P; Scheuer, J; Cai, J-M; Schwarz, I; Retzker, A; Plenio, M B; Katagiri, M; Teraji, T; Koizumi, S; Isoya, J; Fischer, R; McGuinness, L P; Naydenov, B; Jelezko, F

    2013-08-01

    We report the detection and polarization of nuclear spins in diamond at room temperature by using a single nitrogen-vacancy (NV) center. We use Hartmann-Hahn double resonance to coherently enhance the signal from a single nuclear spin while decoupling from the noisy spin bath, which otherwise limits the detection sensitivity. As a proof of principle, we (i)observe coherent oscillations between the NV center and a weakly coupled nuclear spin and (ii)demonstrate nuclear-bath cooling, which prolongs the coherence time of the NV sensor by more than a factor of 5. Our results provide a route to nanometer scale magnetic resonance imaging and novel quantum information processing protocols. PMID:23971612

  18. Local quantum control of Heisenberg spin chains

    SciTech Connect

    Heule, Rahel; Bruder, C.; Stojanovic, Vladimir M.; Burgarth, Daniel

    2010-11-15

    Motivated by some recent results of quantum control theory, we discuss the feasibility of local operator control in arrays of interacting qubits modeled as isotropic Heisenberg spin chains. Acting on one of the end spins, we aim at finding piecewise-constant control pulses that lead to optimal fidelities for a chosen set of quantum gates. We analyze the robustness of the obtained results for the gate fidelities to random errors in the control fields, finding that with faster switching between piecewise-constant controls the system is less susceptible to these errors. The observed behavior falls into a generic class of physical phenomena that are related to a competition between resonance- and relaxation-type behavior, exemplified by motional narrowing in NMR experiments. Finally, we discuss how the obtained optimal gate fidelities are altered when the corresponding rapidly varying piecewise-constant control fields are smoothened through spectral filtering.

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    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.

  20. 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.

  1. Spin Manipulation by Creation of Single-Molecule Radical Cations.

    PubMed

    Karan, Sujoy; Li, Na; Zhang, Yajie; He, Yang; Hong, I-Po; Song, Huanjun; L, Jing-Tao; Wang, Yongfeng; Peng, Lianmao; Wu, Kai; Michelitsch, Georg S; Maurer, Reinhard J; Diller, Katharina; Reuter, Karsten; Weismann, Alexander; Berndt, Richard

    2016-01-15

    All-trans-retinoic acid (ReA), a closed-shell organic molecule comprising only C, H, and O atoms, is investigated on a Au(111) substrate using scanning tunneling microscopy and spectroscopy. In dense arrays single ReA molecules are switched to a number of states, three of which carry a localized spin as evidenced by conductance spectroscopy in high magnetic fields. The spin of a single molecule may be reversibly switched on and off without affecting its neighbors. We suggest that ReA on Au is readily converted to a radical by the abstraction of an electron. PMID:26824562

  2. Spin Manipulation by Creation of Single-Molecule Radical Cations

    NASA Astrophysics Data System (ADS)

    Karan, Sujoy; Li, Na; Zhang, Yajie; He, Yang; Hong, I.-Po; Song, Huanjun; L, Jing-Tao; Wang, Yongfeng; Peng, Lianmao; Wu, Kai; Michelitsch, Georg S.; Maurer, Reinhard J.; Diller, Katharina; Reuter, Karsten; Weismann, Alexander; Berndt, Richard

    2016-01-01

    All-trans-retinoic acid (ReA), a closed-shell organic molecule comprising only C, H, and O atoms, is investigated on a Au(111) substrate using scanning tunneling microscopy and spectroscopy. In dense arrays single ReA molecules are switched to a number of states, three of which carry a localized spin as evidenced by conductance spectroscopy in high magnetic fields. The spin of a single molecule may be reversibly switched on and off without affecting its neighbors. We suggest that ReA on Au is readily converted to a radical by the abstraction of an electron.

  3. Magnetically controlled single-electron shuttle

    NASA Astrophysics Data System (ADS)

    Ilinskaya, O. A.; Kulinich, S. I.; Krive, I. V.; Shekhter, R. I.; Jonson, M.

    2015-01-01

    A theory of single-electron shuttling in an external magnetic field in nanoelectromechanical system with magnetic leads is presented. We consider partially spin-polarized electrons in the leads and electron transport in both the Coulomb blockade regime and in the limit of large bias voltages when the Coulomb blockade is lifted. The influence of the degree of spin polarization on shuttle instability is considered. It is shown that there is certain degree of spin polarization above which the magnetic field ceases to control electron transport. In the Coulomb blockade regime the dependence of the threshold magnetic field, which separates the "shuttle" and vibron regimes, on the degree of polarization is evaluated. The possibility of re-entrant transitions to the shuttle phase is discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    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.

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

    PubMed

    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

  6. Electric g tensor control and spin echo of a hole-spin qubit in a quantum dot molecule

    NASA Astrophysics Data System (ADS)

    Roloff, Robert; Eissfeller, Thomas; Vogl, Peter; Ptz, Walter

    2010-09-01

    The feasibility of high-fidelity single-qubit operations on a hole spin in a quantum dot molecule by electric g tensor control is demonstrated. Apart from a constant external magnetic field the proposed scheme allows for an exclusively electric control of the hole spin. Realistic electric gate bias profiles are identified for various qubit operations using process-tomography-based optimal control. They are shown to be remarkably robust against decoherence and dissipation arising from the interaction of the hole with host-lattice nuclear spins and phonons, with a fidelity loss of ?1% for gate operation times of ?10 ns. Spin-echo experiments for the hole spin are modeled to explore dephasing mechanisms and the role of pulse-timing imperfections in the gate fidelity loss is discussed.

  7. Tools for Studying Electron and Spin Transport in Single Molecules

    NASA Astrophysics Data System (ADS)

    Ralph, Daniel C.

    2005-03-01

    Experiments in the field of single-molecule electronics are challenging in part because it can be very difficult to control and characterize the device structure. Molecules contacted by metal electrodes cannot easily be imaged by microscopy techniques. Moreover, if one attempts to characterize the device structure simply by measuring a current-voltage curve, it is easy to mistake nonlinear transport across a bare tunnel junction or a metallic short for a molecular signal. I will discuss the development of a set of experimental test structures that enable the properties of a molecular device to be tuned controllably in-situ, so that the transport mechanisms can be studied more systematically and compared with theoretical predictions. My collaborators and I are developing the means to use several different types of such experimental "knobs" in coordination: electrostatic gating to shift the energy levels in a molecule, mechanical motion to adjust the molecular configuration or the molecule-electrode coupling strength, illumination with light to promote electrons to excited states or to make and break chemical bonds, and the use of ferromagnetic electrodes to study spin-polarized transport. Our work so far has provided new insights into Kondo physics, the coupling between a molecule's electronic and mechanical degrees of freedom, and spin transport through a molecule between magnetic electrodes. Collaborators: Radek Bialczak, Alex Champagne, Luke Donev, Jonas Goldsmith, Jacob Grose, Janice Guikema, Jiwoong Park, Josh Parks, Abhay Pasupathy, Jason Petta, Sara Slater, Burak Ulgut, Alexander Soldatov, H'ector Abruña, and Paul McEuen.

  8. Control Spin with Candor and Charm.

    ERIC Educational Resources Information Center

    Rist, Marilee C.

    1991-01-01

    On a systemwide level, spin control means defining the issues and formulating an agenda for addressing them. On a personal level, school executives should develop a communications style that stresses honesty, updated information for everyone, wise choice of issues, appropriate responses to criticism, openness to expert advice, willingness to share

  9. 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.

  10. 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.

  11. Two-dimensional nanoscale imaging of gadolinium spins via scanning probe relaxometry with a single spin in diamond

    NASA Astrophysics Data System (ADS)

    Pelliccione, Matthew; Myers, Bryan; Pascal, Laetitia; Das, Anand; Jayich, Ania

    2015-03-01

    Spin-labeling of molecules with paramagnetic ions is an important approach for determining molecular structure, however current ensemble techniques lack the sensitivity to detect few isolated spins. In this talk, we demonstrate two-dimensional nanoscale imaging of paramagnetic gadolinium compounds using scanning relaxometry of a single nitrogen vacancy (NV) center in diamond. Gadopentetate dimeglumine attached to an atomic force microscope tip is controllably interacted with and detected by the NV center, by virtue of the fact that the NV exhibits fast relaxation in the fluctuating magnetic field generated by electron spin flips in the gadolinium. We demonstrate a reduction in the T1 relaxation time of the NV center by over two orders of magnitude, probed with a spatial resolution of 20 nm, limited by thermal drift in ambient conditions. We discuss the importance of mitigating drift to reach truly nanoscale imaging and present progress towards cryogenic scanning magnetometry, along with utilizing chemically functionalized tips to gain greater control over the Gd distribution on the tip. Our result exhibits the viability of the technique for imaging individual spins attached to complex nanostructures or biomolecules, along with studying the magnetic dynamics of isolated spins.

  12. Quantum control and squeezing of collective spin

    NASA Astrophysics Data System (ADS)

    Hemmer, Daniel; Montano, Enrique; Jessen, Poul; Deutsch, Ivan

    2015-05-01

    Quantum control of many body atomic spins is often pursued in the context of an atom-light quantum interface, where a quantized light field can be used to entangle distant atoms. We are currently exploring new ways to improve the coherence and the amount of atom-light entanglement by optimizing the spatial geometry of the atomic ensemble and light fields, and through the control and optimization 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. Using an optimized geometry and a 2-color probe scheme to suppress tensor light shifts we achieve 7 dB of spin noise reduction and 5 dB of metrological squeezing at the optimal measurement time. It is possible to further increase atom-light coupling by ``amplifying'' the initial projection noise per atom through a suitable internal state preparation. In principle we can use internal-state control to map this entanglement back to a basis where it corresponds to improved squeezing.

  13. Nonlinear single-spin spectrum analyzer.

    PubMed

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

    2013-03-15

    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. PMID:25166519

  14. Using nanoscale transistors to measure single donor spins in semiconductors

    SciTech Connect

    Sarovar, M.; Young, K. C.; Whaley, K. B.; Schenkel, Thomas

    2008-12-01

    We propose a technique for measuring the state of a single donor electron spin usinga field-effect transistor induced two-dimensional electron gas and electrically detected magnetic resonance techniques. The scheme is faciltated by hyperfine coupling to the donor nucleus. We analyze the potential sensitivity and outlne experimental reqiurements. Our measurement provides a single-shot, projective, and quantum non-demoltion measurement of an electron-encoded qubit state.

  15. 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.

  16. 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.

  17. Probing a single nuclear spin in a silicon single electron transistor

    NASA Astrophysics Data System (ADS)

    Delgado, F.; Aguado, R.; Fernndez-Rossier, J.

    2012-08-01

    We study single electron transport across a single Bi dopant in a silicon nanotransistor to assess how the strong hyperfine coupling with the Bi nuclear spin I = 9/2 affects the transport characteristics of the device. In the sequential tunneling regime we find that at, temperatures in the range of 100 mK, dI/dV curves reflect the zero field hyperfine splitting as well as its evolution under an applied magnetic field. Our non-equilibrium quantum simulations show that nuclear spins can be partially polarized parallel or antiparallel to the electronic spin just tuning the applied bias.

  18. Long-range spin-triplet correlations and edge spin currents in diffusive spin-orbit coupled SNS hybrids with a single spin-active interface.

    PubMed

    Alidoust, Mohammad; Halterman, Klaus

    2015-06-17

    Utilizing a SU(2) gauge symmetry technique in the quasiclassical diffusive regime, we theoretically study finite-sized two-dimensional intrinsic spin-orbit coupled superconductor/normal-metal/superconductor (S/N/S) hybrid structures with a single spin-active interface. We consider intrinsic spin-orbit interactions (ISOIs) that are confined within the N wire and absent in the s-wave superconducting electrodes (S). Using experimentally feasible parameters, we demonstrate that the coupling of the ISOIs and spin moment of the spin-active interface results in maximum singlet-triplet conversion and accumulation of spin current density at the corners of the N wire nearest the spin-active interface. By solely modulating the superconducting phase difference, we show how the opposing parities of the charge and spin currents provide an effective venue to experimentally examine pure edge spin currents not accompanied by charge currents. These effects occur in the absence of externally imposed fields and moreover are insensitive to the arbitrary orientations of the interface spin moment. The experimental implementation of these robust edge phenomena are also discussed. PMID:25996592

  19. Long-range spin-triplet correlations and edge spin currents in diffusive spin-orbit coupled SNS hybrids with a single spin-active interface

    NASA Astrophysics Data System (ADS)

    Alidoust, Mohammad; Halterman, Klaus

    2015-06-01

    Utilizing a SU(2) gauge symmetry technique in the quasiclassical diffusive regime, we theoretically study finite-sized two-dimensional intrinsic spin-orbit coupled superconductor/normal-metal/superconductor (S/N/S) hybrid structures with a single spin-active interface. We consider intrinsic spin-orbit interactions (ISOIs) that are confined within the N wire and absent in the s-wave superconducting electrodes (S). Using experimentally feasible parameters, we demonstrate that the coupling of the ISOIs and spin moment of the spin-active interface results in maximum singlet-triplet conversion and accumulation of spin current density at the corners of the N wire nearest the spin-active interface. By solely modulating the superconducting phase difference, we show how the opposing parities of the charge and spin currents provide an effective venue to experimentally examine pure edge spin currents not accompanied by charge currents. These effects occur in the absence of externally imposed fields and moreover are insensitive to the arbitrary orientations of the interface spin moment. The experimental implementation of these robust edge phenomena are also discussed.

  20. 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

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

    PubMed

    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

  2. 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 nitrogenvacancy centre spins that interact with the resonant phonon modes of a macroscopic mechanical resonator through crystal strain. However, the nitrogenvacancy spinstrain 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 nitrogenvacancy centre. Via quantum control of the spin, we quantitatively characterize the axial and transverse strain sensitivities of the nitrogenvacancy ground-state spin. The nitrogenvacancy 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 spinphonon interactions in the quantum regime. PMID:25034828

  3. Control of spin waves in a thin film ferromagnetic insulator through interfacial spin scattering.

    PubMed

    Wang, Zihui; Sun, Yiyan; Wu, Mingzhong; Tiberkevich, Vasil; Slavin, Andrei

    2011-09-30

    Control of spin waves in a ferrite thin film via interfacial spin scattering was demonstrated. The experiments used a 4.6???m-thick yttrium iron garnet (YIG) film strip with a 20-nm thick Pt capping layer. A dc current pulse was applied to the Pt layer and produced a spin current across the Pt thickness. As the spin current scatters off the YIG surface, it can either amplify or attenuate spin-wave pulses that travel in the YIG strip, depending on the current or field configuration. The spin scattering also affects the saturation behavior of high-power spin waves. PMID:22107222

  4. 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

  5. Spin-valley qubit in nanostructures of monolayer semiconductors: Optical control and hyperfine interaction

    NASA Astrophysics Data System (ADS)

    Wu, Yue; Tong, Qingjun; Liu, Gui-Bin; Yu, Hongyi; Yao, Wang

    2016-01-01

    We investigate the optical control possibilities of spin-valley qubit carried by single electrons localized in nanostructures of monolayer TMDs, including small quantum dots formed by lateral heterojunction and charged impurities. The quantum controls are discussed when the confinement induces valley hybridization and when the valley hybridization is absent. We show that the bulk valley and spin optical selection rules can be inherited in different forms in the two scenarios, both of which allow the definition of spin-valley qubit with desired optical controllability. We also investigate nuclear spin-induced decoherence and quantum control of electron-nuclear spin entanglement via intervalley terms of the hyperfine interaction. Optically controlled two-qubit operations in a single quantum dot are discussed.

  6. Single-chip detector for electron spin resonance spectroscopy.

    PubMed

    Yalcin, T; Boero, G

    2008-09-01

    We have realized an innovative integrated detector for electron spin resonance spectroscopy. The microsystem, consisting of an LC oscillator, a mixer, and a frequency division module, is integrated onto a single silicon chip using a conventional complementary metal-oxide-semiconductor technology. The implemented detection method is based on the measurement of the variation of the frequency of the integrated LC oscillator as a function of the applied static magnetic field, caused by the presence of a resonating sample placed over the inductor of the LC-tank circuit. The achieved room temperature spin sensitivity is about 10(10) spinsGHz(12) with a sensitive volume of about (100 microm)(3). PMID:19044436

  7. Single-chip detector for electron spin resonance spectroscopy

    SciTech Connect

    Yalcin, T.; Boero, G.

    2008-09-15

    We have realized an innovative integrated detector for electron spin resonance spectroscopy. The microsystem, consisting of an LC oscillator, a mixer, and a frequency division module, is integrated onto a single silicon chip using a conventional complementary metal-oxide-semiconductor technology. The implemented detection method is based on the measurement of the variation of the frequency of the integrated LC oscillator as a function of the applied static magnetic field, caused by the presence of a resonating sample placed over the inductor of the LC-tank circuit. The achieved room temperature spin sensitivity is about 10{sup 10} spins/GHz{sup 1/2} with a sensitive volume of about (100 {mu}m){sup 3}.

  8. Coherent control of three-spin states in a triple quantum dot

    NASA Astrophysics Data System (ADS)

    Gaudreau, L.; Granger, G.; Kam, A.; Aers, G. C.; Studenikin, S. A.; Zawadzki, P.; Pioro-Ladrire, M.; Wasilewski, Z. R.; Sachrajda, A. S.

    2012-01-01

    Spin qubits involving individual spins in single quantum dots or coupled spins in double quantum dots have emerged as potential building blocks for quantum information processing applications. It has been suggested that triple quantum dots may provide additional tools and functionalities. These include encoding information either to obtain protection from decoherence or to permit all-electrical operation, efficient spin busing across a quantum circuit, and to enable quantum error correction using the three-spin Greenberger-Horn-Zeilinger quantum state. Towards these goals we demonstrate coherent manipulation of two interacting three-spin states. We employ the Landau-Zener-Stckelberg approach for creating and manipulating coherent superpositions of quantum states. We confirm that we are able to maintain coherence when decreasing the exchange coupling of one spin with another while simultaneously increasing its coupling with the third. Such control of pairwise exchange is a requirement of most spin qubit architectures, but has not been previously demonstrated.

  9. Controlling Spin Relaxation in Hexagonal BN-Encapsulated Graphene with a Transverse Electric Field

    NASA Astrophysics Data System (ADS)

    Guimarães, M. H. D.; Zomer, P. J.; Ingla-Aynés, J.; Brant, J. C.; Tombros, N.; van Wees, B. J.

    2014-08-01

    We experimentally study the electronic spin transport in hexagonal BN encapsulated single layer graphene nonlocal spin valves. The use of top and bottom gates allows us to control the carrier density and the electric field independently. The spin relaxation times in our devices range up to 2 ns with spin relaxation lengths exceeding 12 μm even at room temperature. We obtain that the ratio of the spin relaxation time for spins pointing out-of-plane to spins in-plane is τ⊥/τ||≈0.75 for zero applied perpendicular electric field. By tuning the electric field, this anisotropy changes to ≈0.65 at 0.7 V/nm, in agreement with an electric field tunable in-plane Rashba spin-orbit coupling.

  10. 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 by changing the gate voltage. It provides us a new way to control surface magnetism electrically. The gap opened by doped magnetic ions can lead to a short-range Bloembergen-Rowland interaction. The competition among the Heisenberg, Ising, and DM terms leads to rich spin configurations and an anomalous Hall effect on different lattices [4]. There are many proposals for quantum computation scheme are based on the spin in semiconductor quantum dots. Topological insulator quantum dots display a very different behavior with that of conventional semiconductor quantum dots [5]. In sharp contrast to conventional semiconductor quantum dots, the quantum states in the gap of the HgTe QD are fully spin-polarized and show ring-like density distributions near the boundary of the QD and optically dark. The persistent charge currents and magnetic moments, i.e., the Aharonov-Bohm effect, can be observed in such a QD structure. This feature offers us a practical way to detect these exotic ring-like edge states by using the SQUID technique. [0pt]Refs: [1] W. Yang, Kai Chang, and S. C. Zhang, Phys. Rev. Lett. 100, 056602 (2008); J. Li and Kai Chang, Appl. Phys. Lett. 95, 222110 (2009). [2] L. B. Zhang, Kai Chang, X. C. Xie, H. Buhmann and L. W. Molenkamp, New J. Phys. 12, 083058 (2010). [3] L. B. Zhang, F. Cheng, F. Zhai and Kai Chang, Phys. Rev. B 83 081402(R) (2011); Z. H. Wu, F. Zhai, F. M. Peeters, H. Q. Xu and Kai Chang, Phys, Rev. Lett. 106, 176802 (2011). [4] J. J. Zhu, D. X. Yao, S. C. Zhang, and Kai Chang, Phys. Rev. Lett. 106, 097201 (2011). [5] Kai Chang, and Wen-Kai Lou, Phys. Rev. Lett. 106, 206802 (2011).

  11. Electric-field sensing using single diamond spins

    NASA Astrophysics Data System (ADS)

    Dolde, F.; Fedder, H.; Doherty, M. W.; Nöbauer, T.; Rempp, F.; Balasubramanian, G.; Wolf, T.; Reinhard, F.; Hollenberg, L. C. L.; Jelezko, F.; Wrachtrup, J.

    2011-06-01

    The ability to sensitively detect individual charges under ambient conditions would benefit a wide range of applications across disciplines. However, most current techniques are limited to low-temperature methods such as single-electron transistors, single-electron electrostatic force microscopy and scanning tunnelling microscopy. Here we introduce a quantum-metrology technique demonstrating precision three-dimensional electric-field measurement using a single nitrogen-vacancy defect centre spin in diamond. An a.c. electric-field sensitivity reaching 202+/-6Vcm-1Hz-1/2 has been achieved. This corresponds to the electric field produced by a single elementary charge located at a distance of ~150nm from our spin sensor with averaging for one second. The analysis of the electronic structure of the defect centre reveals how an applied magnetic field influences the electric-field-sensing properties. We also demonstrate that diamond-defect-centre spins can be switched between electric- and magnetic-field sensing modes and identify suitable parameter ranges for both detector schemes. By combining magnetic- and electric-field sensitivity, nanoscale detection and ambient operation, our study should open up new frontiers in imaging and sensing applications ranging from materials science to bioimaging.

  12. Cryogenic single-chip electron spin resonance detector.

    PubMed

    Gualco, Gabriele; Anders, Jens; Sienkiewicz, Andrzej; Alberti, Stefano; Forr, Lszl; Boero, Giovanni

    2014-10-01

    We report on the design and characterization of a single-chip electron spin resonance detector, operating at a frequency of about 20 GHz and in a temperature range extending at least from 300 K down to 4 K. The detector consists of an LC oscillator formed by a 200 ?m diameter single turn aluminum planar coil, a metal-oxide-metal capacitor, and two metal-oxide-semiconductor field effect transistors used as negative resistance network. At 300 K, the oscillator has a frequency noise of 20 Hz/Hz(1/2) at 100 kHz offset from the 20 GHz carrier. At 4 K, the frequency noise is about 1 Hz/Hz(1/2) at 10 kHz offset. The spin sensitivity measured with a sample of DPPH is 10(8)spins/Hz(1/2) at 300 K and down to 10(6)spins/Hz(1/2) at 4 K. PMID:25261743

  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. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    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.

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

    PubMed

    Jamonneau, P; Htet, G; Drau, 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 ? 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 ?-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

  17. Optimal control of spin stabilized spacecraft with telescoping appendages

    NASA Technical Reports Server (NTRS)

    Bainum, P. M.; Sellappan, R.

    1976-01-01

    The control of a spin-stabilized spacecraft consisting of a rigid central hub and one or two movable offset telescoping booms (with end masses) is considered. The equations of rotational motion are linearized about either of two desired final states. A control law for the boom and mass position is sought such that a quadratic cost functional involving the weighted components of angular velocity plus the control is minimized when the final time is unspecified and involves the solution of the matrix Riccati algebraic equation. For three-axis control more than one offset boom (orthogonal to each other) is required. For two-axis control with a single boom offset from a symmetrical hub, an analytic solution is obtained; when this system is used for nutation decay the time constant is one order of magnitude smaller than previously achieved using non-optimal control logic. For the general case results are obtained numerically.

  18. Optimal control of spin-stabilized spacecraft with telescoping appendages

    NASA Technical Reports Server (NTRS)

    Bainum, P. M.; Sellappan, R.

    1976-01-01

    The control of a spin-stabilized spacecraft consisting of a rigid central hub and one or two movable offset telescoping booms (with end masses) is considered. The equations of rotational motion are linearized about either of two desired final states. A control law for the boom end mass position is sought such that a quadratic cost functional involving the weighted components of angular velocity plus the control is minimized when the final time is unspecified and involves the solution of the matrix Riccati algebraic equation. For three axis control more than one offset boom (orthogonal to each other) is required. For two-axis control with a single boom offset from a symmetrical hub, an analytic solution is obtained; when this system is used for nutation decay the time constant is one order of magnitude smaller than previously achieved using nonoptimal control logic. For the general case results are obtained numerically.

  19. Transverse single spin asymmetry in hadronic ?c,b production

    NASA Astrophysics Data System (ADS)

    Schfer, Andreas; Zhou, Jian

    2013-07-01

    We study the transverse single spin asymmetry in ?c,b production in polarized hadron collisions, employing the collinear twist-3 approach in combination with the color singlet model. Our main focus lies on the contribution from the twist-3 Efremov-Teryaev-Qiu-Sterman function. By extrapolating the derived spin-dependent cross section to the small transverse momentum region, consistency between the collinear twist-3 approach and the transverse-momentum-dependent factorization approach is confirmed. As a byproduct of this work, we identify a term contributing to the scale evolution of trigluon correlations in the flavor-singlet case which was originally missed, see also V. M. Braun, A. N. Manashov, and B. Pirnay [Phys. Rev. D 80, 114002 (2009); PRVDAQ1550-799886, 119902(E) (2012)].

  20. 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.

  1. 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 ?ms = -1 to +1 spin state splitting energy is tuned into resonance with a driven mechanical mode, we observe ?ms = +/-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.

  2. High-fidelity readout and control of a nuclear spin qubit in silicon.

    PubMed

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

    2013-04-18

    Detection of nuclear spin precession is critical for a wide range of scientific techniques that have applications in diverse fields including analytical chemistry, materials science, medicine and biology. Fundamentally, it is possible because of the extreme isolation of nuclear spins from their environment. This isolation also makes single nuclear spins desirable for quantum-information processing, as shown by pioneering studies on nitrogen-vacancy centres in diamond. The nuclear spin of a (31)P donor in silicon is very promising as a quantum bit: bulk measurements indicate that it has excellent coherence times and silicon is the dominant material in the microelectronics industry. Here we demonstrate electrical detection and coherent manipulation of a single (31)P nuclear spin qubit with sufficiently high fidelities for fault-tolerant quantum computing. By integrating single-shot readout of the electron spin with on-chip electron spin resonance, we demonstrate quantum non-demolition and electrical single-shot readout of the nuclear spin with a readout fidelity higher than 99.8 percent-the highest so far reported for any solid-state qubit. The single nuclear spin is then operated as a qubit by applying coherent radio-frequency pulses. For an ionized (31)P donor, we find a nuclear spin coherence time of 60 milliseconds and a one-qubit gate control fidelity exceeding 98 percent. These results demonstrate that the dominant technology of modern electronics can be adapted to host a complete electrical measurement and control platform for nuclear-spin-based quantum-information processing. PMID:23598342

  3. Controllable spin-current blockade in a Hubbard chain

    NASA Astrophysics Data System (ADS)

    Yao, Yao; Zhao, Hui; Moore, Joel E.; Wu, Chang-Qin

    2008-11-01

    We investigate the spin or charge transport in a one-dimensional strongly correlated system by using the adaptive time-dependent density-matrix renormalization-group method. The model we consider is a non-half-filled Hubbard chain with a bond of controllable spin-dependent electron hoppings, which is found to cause a blockade of spin current with little influence on charge current. We have considered (1) the spread of a wave packet of both spin and charge and (2) the spin and charge currents induced by a spin-dependent voltage bias. It is found that the spin-charge separation plays a crucial role in the spin-current blockade, which may be utilized to observe the spin-charge separation directly.

  4. Injection, detection and gate voltage control of spins in the spin field effect transistor

    NASA Astrophysics Data System (ADS)

    Chang, Joonyeon; Cheol Koo, Hyun; Eom, Jonghwa; Hee Han, Suk; Johnson, Mark

    2011-05-01

    We demonstrate electrical spin injection and gate voltage control of spin precession in an InAs quantum well channel that has Permalloy injector and detector, and is covered by a gate oxide and a Au gate electrode. The electrical injection and detection of ballistic spin-polarized electrons are characterized using conventional lateral spin valve techniques. An external magnetic field is used to overcome the shape anisotropy of the magnetizations of injector and detector. We can then inject spins that have both spin orientation and velocity along the axis of the channel, and we observe an oscillatory channel conductance as a function of monotonically increasing gate voltage. This conductance oscillation is the hallmark of a spin field effect transistor. After presenting the basic results, we discuss issues associated with (1) the Hanle effect in a two-dimensional electron gas with high spin-orbit interaction and (2) the observation of a conductance oscillation in a multimode (two-dimensional) channel.

  5. Spin amplification by controlled symmetry breaking for spin-based logic

    NASA Astrophysics Data System (ADS)

    Kawakami, Roland K.

    2015-09-01

    Spin amplification is one of the most critical challenges for spintronics and spin-based logic in order to achieve spintronic circuits with fan-out. We propose a new concept for spin amplification that will allow a small spin current in a non-magnetic spin channel to control the magnetization of an attached ferromagnet. The key step is to bring the ferromagnet into an unstable symmetric state (USS), so that a small spin transfer torque from a small spin current can provide a magnetic bias to control the spontaneous symmetry breaking and select the final magnetization direction of the ferromagnet. Two proposed methods for achieving the USS configuration are voltage-controlled Curie temperature (VC-TC) and voltage-controlled magnetic anisotropy (VC-MA). We believe the development of new 2D magnetic materials with greater tunability of VC-TC and VC-MA will be needed for practical applications. A successful realization of spin amplification by controlled symmetry breaking will be important for the implementation of existing spin-logic proposals (e.g. all spin logic) and could inspire alternative ideas for spintronic circuits and devices.

  6. Sivers Single-Spin Asymmetry in Photon-Jet Production

    SciTech Connect

    Bacchetta, Alessandro; Bomhof, Cedran; Mulders, Piet J.; D'Alesio, Umberto; Murgia, Francesco

    2007-11-23

    We study a weighted asymmetry in the azimuthal distribution of photon-jet pairs produced in the process p{sup {up_arrow}}p{yields}{gamma} jet X with a transversely polarized proton. We focus on the contribution of the Sivers effect only, considering experimental configurations accessible at the Relativistic Heavy Ion Collider. We show that predictions for the asymmetry, obtained in terms of gluonic-pole cross sections calculable in perturbative QCD, can be tested and clearly discriminated from those based on a generalized parton model, involving standard partonic cross sections. Experimental measurements of the asymmetry will therefore test our present understanding of single-spin asymmetries.

  7. Imaging and controlling spins in semiconductors and ferromagnets

    NASA Astrophysics Data System (ADS)

    Nowakowski, Mark Edward

    Spins possess robust coherent and exchange-driven properties in semiconductors and ferromagnets. In this work, we investigate three experiments that incorporate and exploit these spin properties to demonstrate innovated quantum information processing, magnetic detection and control techniques. In the first experiment we spatially confine an effective magnetic field to control the coherent state of moving electron spins. Optically-injected electron spin ensembles are transported through a gate-controlled, spatially-isolated region with a large effective magnetic field created by locally polarized nuclear spins within a GaAs channel at T = 8 K. By tuning the localized effective field strength and drift velocity we detect, using time-resolved Kerr rotation (TRKR), induced spin rotations of up to 5pi radians in 6 ns over a 30 mum distance. In the second experiment, we develop a sensitive electrical technique derived from the anomalous Hall effect (AHE) to measure domain wall (DW) motion with nanometer precision. We then use this system to study the elastic properties of single ferromagnetic DWs in (Ga,Mn)As. Full understanding of the electrical signal is only possible after accurately determining the DW location with respect to the electrical contacts. Therefore, we image the DWs using a custom-built, diffraction-limited video magneto-optical Kerr effect (MOKE) microscopy system while simultaneously measuring the AHE. By combining these detection schemes we are able to precisely measure temperature-dependent elastic DW dynamics and kinetics below TC. Finally, the third experiment relates our progress toward understanding the coupling between the multiferroic oxide BiFeO3 (BFO) and a CoFe magnetic layer. The exchange-bias mediated coupling between ferroelectric domains of the BFO and ferromagnetic domains in the CoFe layer suggest a pathway to realize electrical control of the magnetization properties. We investigate and model the ferroelectric influence on magnetocrystalline anisotropies in the CoFe thin film by measuring the static and dynamical magnetic properties using anisotropic magnetoresistance (AMR) and transport-based ferromagnetic resonance (FMR) measurements.

  8. Quantifying the quantum gate fidelity of single-atom spin qubits in silicon by randomized benchmarking.

    PubMed

    Muhonen, J T; Laucht, A; Simmons, S; Dehollain, J P; Kalra, R; Hudson, F E; Freer, S; Itoh, K M; Jamieson, D N; McCallum, J C; Dzurak, A S; Morello, A

    2015-04-22

    Building upon the demonstration of coherent control and single-shot readout of the electron and nuclear spins of individual (31)P atoms in silicon, we present here a systematic experimental estimate of quantum gate fidelities using randomized benchmarking of 1-qubit gates in the Clifford group. We apply this analysis to the electron and the ionized (31)P nucleus of a single P donor in isotopically purified (28)Si. We find average gate fidelities of 99.95% for the electron and 99.99% for the nuclear spin. These values are above certain error correction thresholds and demonstrate the potential of donor-based quantum computing in silicon. By studying the influence of the shape and power of the control pulses, we find evidence that the present limitation to the gate fidelity is mostly related to the external hardware and not the intrinsic behaviour of the qubit. PMID:25783435

  9. 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.

  10. 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.

  11. Optical control and coherence of electron or hole spins in coupled quantum dots

    NASA Astrophysics Data System (ADS)

    Carter, Samuel

    2013-03-01

    The spin of an electron or hole in an InAs quantum dot is an attractive qubit because it combines the advantages of a semiconductor platform with the power of ultrafast optical coherent control techniques. In the last few years, basic quantum operations such as initialization, rotation, and readout have become possible using single spins, but now improvements in spin coherence and demonstrations of multi-qubit systems are needed. In this work, we combine advances in the design and growth of coupled quantum dots with optical coherent control techniques to demonstrate ultrafast manipulation and coherence improvements for one or two interacting electron or hole spins in a coupled pair of InAs dots. For each of these spin systems, we use a sequence of picosecond and nanosecond pulses to initialize, manipulate, and measure the coherent spin dynamics. These dynamics include precession about a magnetic field and also entangling dynamics from the exchange interaction for coupled spins. For a single electron spin, precession dephases after only a few nanoseconds due to the hyperfine interaction with nuclear spins. For hole spins, we measure a dephasing time an order of magnitude longer due to a weaker hyperfine interaction. Coupled electron and hole spins are essential for multi-qubit systems, and they can also be used to decrease sensitivity to the environment. In these systems, we typically measure the coherent dynamics of the singlet-triplet states (ms = 0), which are much less sensitive to the nuclear environment. At present, dephasing is due to fluctuations in the electrical environment. With careful sample design, we can make these systems much less sensitive to electrical fluctuations, giving a powerful combination of long coherence times and ultrafast gates. Finally, we demonstrate that these spin qubits can be incorporated into a photonic crystal cavity and manipulated with optical pulses, a major step toward a quantum interface between photons and these spin qubits.

  12. 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.

  13. Electrically controllable spin pumping in graphene via rotating magnetization

    NASA Astrophysics Data System (ADS)

    Rahimi, Mojtaba A.; Moghaddam, Ali G.

    2015-07-01

    We investigate pure spin pumping in graphene by imposing a ferromagnet (F) with rotating magnetization on top of it. Using the generalized scattering approach for adiabatic spin pumping, we obtain the spin current pumped through magnetic graphene to the normal (N) region. This spin current which can be easily controlled by gate voltages, reaches sufficiently large values measurable in current experimental setups. The spin current reaches its maximum when one of the spins is completely filtered because of its vanishing density of states in the ferromagnetic part. In order to study the effect of the ferromagnetic part length on the pumped spin current, the N—F—N structure is considered. It is found that in contrast to the metallic ferromagnetic materials the transverse spin coherence length can be comparable to the length of F. Subsequently, due to the quantum interferences inside the middle F region, the spin current becomes an oscillatory function of JL/\\hbar {{v}\\text{F}} in which J is the spin splitting and L is the length of F. Finally controllability of the pumped spin into two different normal sides in the N—F—N hybrid device gives rise to the spin battery effect.

  14. Manipulation of a single Mn spin using excitation transfer between two coupled CdTe/ZnTe quantum dots

    NASA Astrophysics Data System (ADS)

    Goryca, Mateusz

    2010-02-01

    A semiconductor quantum dot (QD) containing a single Mn atom is a promising system from the point of view of future information processing and storage devices. An efficient optical read-out of the single Mn spin state in a CdTe/ZnTe quantum dot, as well as studies of dynamics of this state, were recently reported by L. Besombes and co-workers. However, to construct the building blocks of future memory devices basing on single magnetic atoms the ability to control a single spin is still needed. This work is focused on the advancement in writing and storing of information on the Mn spin state. We demonstrate optical writing of information on the spin state of a single Mn ion embedded in a CdTe QD and we test the storage time in the range of a few tenths of a millisecond. A spin-conserving excitation transfer between two coupled QDs is used as a tool for optical manipulation of the Mn spin. Excitons resonantly created in a dot without magnetic atom by circularly polarized light tunnel to the dot with the Mn ion in a few picoseconds. Then they act on the Mn ion via the sp-d exchange interaction and orient its spin. The orientation is much more efficient in presence of a magnetic field of about 1T, due to suppression of fast spin relaxation channels. Dynamics of the Mn spin under polarized excitation as well as the information storage time on the Mn spin was measured in a time-resolved experiment, in which the intensity and polarization of excitation were modulated. Observed dynamics can be described with a simple rate equation model. The storage time was enhanced by the magnetic field and reached about half a millisecond at 1T.

  15. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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 10-7. The observed ISHE in SLG is ascribed to its non-negligible spin-orbit interaction in SLG.

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

    PubMed

    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. PMID:26472370

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

    PubMed

    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??B 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

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

    NASA Astrophysics Data System (ADS)

    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 ?B 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.

  20. 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??B 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

  1. 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.

  2. 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.

  3. Multiple Reflection Effect on Spin-Transfer Torque Dynamics in Spin Valves with a Single or Dual Polarizer

    NASA Astrophysics Data System (ADS)

    Zhu, Weiwei; Zhang, Zongzhi; Zhang, Jianwei; Liu, Yaowen

    2015-04-01

    In this paper, spin-dependent multiple reflection effect on spin-transfer torque (STT) has been theoretically and numerically studied in a spin valve nanopillar with a single or dual spin-polarizer. By using a scattering matrix method, we formulate an analytical expression of STT that contains the multiple interfacial reflection effect. It is found that the multiple reflections could enhance the STT efficiency and reduce the critical switching current. The STT efficiency depends on the spin polarization of both the free layer and polarizer. In the nanopillars with a dual spin polarizer, the multiple reflections would cause an asymmetric frequency dependence on the applied current, albeit exactly the same parameters are used in all three ferromagnetic layers, indicating that the frequency in the negative current varies much faster than that in the positive case.

  4. Electric control of spin in monolayer WSe? 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(?, s) in the FET is labelled by both the valley index and spin index, realizing valleytronics and spintronics in the same device. PMID:25287881

  5. 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.

  6. 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.

  7. Global fitting of single spin asymmetry: an attempt

    SciTech Connect

    Alexey Prokudin,Zhong-Bo Kang

    2012-04-01

    We present an attempt of global analysis of Semi-Inclusive Deep Inelastic Scattering (SIDIS) $\\ell p^\\uparrow \\to \\ell' \\pi X$ data on single spin asymmetries and data on left-right asymmetry $A_N$ in $p^\\uparrow p \\to \\pi X$ in order to simultaneously extract information on Sivers function and twist-three quark-gluon Efremov-Teryaev-Qiu-Sterman (ETQS) function. We explore different possibilities such as node of Sivers function in $x$ or $k_\\perp$ in order to explain ``sign mismatch'' between these functions. We show that $\\pi^\\pm$ SIDIS data and $\\pi^0$ STAR data can be well described in a combined TMD and twist-3 fit, however $\\pi^\\pm$ BRAHMS data are not described in a satisfactory way. This leaves open a question to the solution of the ``sign mismatch''. Possible explanations are then discussed.

  8. 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 ?p???'?X data on single spin asymmetries and data on left-right asymmetry AN in p?p??X 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 ? semi-inclusive deep inelastic scattering data and ?0 STAR data can be well described in a combined fit based on both the transverse momentum dependent and collinear twist-three factorization formalisms; however, ? 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.

  9. 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.

  10. Controllable spin-transfer torque on an antiferromagnet in a dual spin-valve

    NASA Astrophysics Data System (ADS)

    Linder, Jacob

    2011-09-01

    We consider current-induced spin-transfer torque on an antiferromagnet (AFM) in a dual spin-valve setup. It is demonstrated that a net magnetization may be induced in the AFM by partially or completely aligning the sublattice magnetizations via a current-induced spin-transfer torque. This effect occurs for current densities ranging below 106 A/cm2. The direction of the induced magnetization in the AFM is shown to be efficiently controlled by means of the magnetic configuration of the spin-valve setup, with the antiparallell configuration yielding the largest spin-transfer torque. Interestingly, the magnetization switching time scale τswitch itself has a strong, nonmonotonic dependence on the spin-valve configuration. These results may point toward new ways to incorporate AFMs in spintronic devices to obtain novel types of functionality.

  11. Robust micromagnet design for fast electrical manipulations of single spins in quantum dots

    NASA Astrophysics Data System (ADS)

    Yoneda, Jun; Otsuka, Tomohiro; Takakura, Tatsuki; Pioro-Ladrire, Michel; Brunner, Roland; Lu, Hong; Nakajima, Takashi; Obata, Toshiaki; Noiri, Akito; Palmstrm, Christopher J.; Gossard, Arthur C.; Tarucha, Seigo

    2015-08-01

    Tailoring spin coupling to electric fields is central to spintronics and spin-based quantum information processing. We present an optimal micromagnet design that produces appropriate stray magnetic fields to mediate fast electrical spin manipulations in nanodevices. We quantify the practical requirements for spatial field inhomogeneity and tolerance for misalignment with spins, and propose a design scheme to improve the spin-rotation frequency (to exceed 50 MHz in GaAs nanostructures). We then validate our design by experiments in separate devices. Our results will open a route to rapidly control solid-state electron spins with limited lifetimes and to study coherent spin dynamics in solids.

  12. Single-axis gyroscopic motion with uncertain angular velocity about spin axis

    NASA Technical Reports Server (NTRS)

    Singh, S. N.

    1977-01-01

    A differential game approach is presented for studying the response of a gyro by treating the controlled angular velocity about the input axis as the evader, and the bounded but uncertain angular velocity about the spin axis as the pursuer. When the uncertain angular velocity about the spin axis desires to force the gyro to saturation a differential game problem with two terminal surfaces results, whereas when the evader desires to attain the equilibrium state the usual game with single terminal manifold arises. A barrier, delineating the capture zone (CZ) in which the gyro can attain saturation and the escape zone (EZ) in which the evader avoids saturation is obtained. The CZ is further delineated into two subregions such that the states in each subregion can be forced on a definite target manifold. The application of the game theoretic approach to Control Moment Gyro is briefly discussed.

  13. Magnetic resonance force microscopy with a single spin S>1/2

    NASA Astrophysics Data System (ADS)

    Fan, Thomas; Tsifrinovich, Vladimir I.

    2009-11-01

    We studied theoretically detection of a single spin S>1/2 using magnetic resonance force microscopy (MRFM) and taking into account anisotropy. We have shown that the MRFM signal for a spin S>1/2 is the same as for spin S=1/2 and obtained the analytical estimate for the half-width of the signal.

  14. Understanding and controlling spin-systems using electron spin resonance techniques

    NASA Astrophysics Data System (ADS)

    Martens, Mathew

    Single molecule magnets (SMMs) posses multi-level energy structures with properties that make them attractive candidates for implementation into quantum information technologies. However there are some major hurdles that need to be overcome if these systems are to be used as the fundamental components of an eventual quantum computer. One such hurdle is the relatively short coherence times these systems display which severely limits the amount of time quantum information can remain encoded within them. In this dissertation, recent experiments conducted with the intent of bringing this technology closer to realization are presented. The detailed knowledge of the spin Hamiltonian and mechanisms of decoherence in SMMs are absolutely essential if these systems are to be used in technologies. To that effect, experiments were done on a particularly promising SMM, the complex K6[VIV15AsIII 6O42(H2O)] · 8H2O, known as V15. High-field electron spin resonance (ESR) measurements were performed on this system at the National High Magnetic Field Laboratory. The resulting spectra allowed for detailed analysis of the V15 spin Hamiltonian which will be presented as well as the most precise values yet reported for the g-factors of this system. Additionally, the line widths of the ESR spectra are studied in depth and found to reveal that fluctuations within the spin-orbit interaction are a mechanism for decoherence in V15. A new model for decoherence is presented that describes very well both the temperature and field orientation dependences of the measured ESR line widths. Also essential is the ability to control spin-states of SMMs. Presented in this dissertation as well is the demonstration of the coherent manipulation of the multi-state spin system Mn2+ diluted in MgO by means of a two-tone pulse drive. Through the detuning between the excitation and readout radio frequency pulses it is possible to select the number of photons involved in a Rabi oscillation as well as increase the frequency of this nutation. Experimental findings fit well the analytical model developed. This process could lead to the use of multi-level spin systems as tunable solid state qubits. Finally, if quantum computing technologies are to be commercially realized, an on-chip method to address qubits must be developed. One way to incorporate SMMs to an on-chip device is by way of a coplanar waveguide (CPW) resonator. Efforts to create a resonator of this type to be used to perform low-temperature ESR on-chip will be described. Our work is focused on implementing such on-chip techniques in high magnetic fields, which is desirable for ESR-type of experiments in (quasi-)isotropic spin systems. Considerable attention is given to the coupling of these devices and a geometry is presented for a superconducting CPW resonator that is critically coupled. The effect of the magnetic field on the resonance position and its quality factor is addressed as well. Our devices show robust performance in field upwards of 1 Tesla and their use in performing on-chip ESR measurements seem promising.

  15. All-Optical Preparation of Coherent Dark States of a Single Rare Earth Ion Spin in a Crystal.

    PubMed

    Xia, Kangwei; Kolesov, Roman; Wang, Ya; Siyushev, Petr; Reuter, Rolf; Kornher, Thomas; Kukharchyk, Nadezhda; Wieck, Andreas D; Villa, Bruno; Yang, Sen; Wrachtrup, Jrg

    2015-08-28

    All-optical addressing and coherent control of single solid-state based quantum bits is a key tool for fast and precise control of ground-state spin qubits. So far, all-optical addressing of qubits was demonstrated only in a very few systems, such as color centers and quantum dots. Here, we perform high-resolution spectroscopic of native and implanted single rare earth ions in solid, namely, a cerium ion in yttrium aluminum garnet (YAG) crystal. We find narrow and spectrally stable optical transitions between the spin sublevels of the ground and excited optical states. Utilizing these transitions we demonstrate the generation of a coherent dark state in electron spin sublevels of a single Ce^{3+} ion in YAG by coherent population trapping. PMID:26371651

  16. All-Optical Preparation of Coherent Dark States of a Single Rare Earth Ion Spin in a Crystal

    NASA Astrophysics Data System (ADS)

    Xia, Kangwei; Kolesov, Roman; Wang, Ya; Siyushev, Petr; Reuter, Rolf; Kornher, Thomas; Kukharchyk, Nadezhda; Wieck, Andreas D.; Villa, Bruno; Yang, Sen; Wrachtrup, Jrg

    2015-08-01

    All-optical addressing and coherent control of single solid-state based quantum bits is a key tool for fast and precise control of ground-state spin qubits. So far, all-optical addressing of qubits was demonstrated only in a very few systems, such as color centers and quantum dots. Here, we perform high-resolution spectroscopic of native and implanted single rare earth ions in solid, namely, a cerium ion in yttrium aluminum garnet (YAG) crystal. We find narrow and spectrally stable optical transitions between the spin sublevels of the ground and excited optical states. Utilizing these transitions we demonstrate the generation of a coherent dark state in electron spin sublevels of a single Ce3 + ion in YAG by coherent population trapping.

  17. Role of electron-electron scattering on spin transport in single layer graphene

    SciTech Connect

    Ghosh, Bahniman; Katiyar, Saurabh; Salimath, Akshaykumar

    2014-01-15

    In this work, the effect of electron-electron scattering on spin transport in single layer graphene is studied using semi-classical Monte Carlo simulation. The Dyakonov-Perel mechanism is considered for spin relaxation. It is found that electron-electron scattering causes spin relaxation length to decrease by 35% at 300 K. The reason for this decrease in spin relaxation length is that the ensemble spin is modified upon an e-e collision and also e-e scattering rate is greater than phonon scattering rate at room temperature, which causes change in spin relaxation profile due to electron-electron scattering.

  18. Exploring magnetic excitations in the condensed matter using single electron spins

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    Pushing the frontiers of condensed-matter magnetism requires tools to probe magnetic excitations on the nanometer scale. We have developed a new approach to exploring magnetic excitations in correlated-electron systems, using magnetometry based on single electron spins in diamond. We demonstrate the power of this approach by detecting spin-wave excitations in a ferromagnetic microdisc with nanoscale spatial sensitivity over a broad range of frequencies and magnetic fields. In addition, we show how spin-wave resonances can be exploited for on-chip amplification of microwave magnetic fields, allowing strongly increased spin manipulation rates and single-spin magnetometry with enhanced sensitivity. These results can be directly applied to nanoscale magnetic imaging of spin-wave propagation and magnetic vortex/skyrmion dynamics, and open the way towards spin-spin coupling via ferromagnets.

  19. 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.

  20. Modeling and Simulations of a Single-Spin Measurement Using MRFM

    NASA Astrophysics Data System (ADS)

    Berman, G. P.; Borgonovi, F.; Gorshkov, V. N.; Tsifrinovich, V. I.

    2005-01-01

    We review the quantum theory of a single spin magnetic resonance force microscopy (MRFM). We concentrate on the novel technique called oscillating cantilever-driven adiabatic reversals (OSCAR), which has been used for a single spin detection (Dan Rugar, Talk on the 2004 IEEE NTC Quantum Device Technology Workshop). First we describe the quantum dynamics of the cantilever-spin system using simple estimates in the spirit of the mean field approximation. Then we present the results of our computer simulations of the Schrodinger equation for the wave function of the cantilever-spin system and of the master equation for the density matrix of the system. We demonstrate that the cantilever behaves like a quasi-classical measurement device which detects the spin projection along the effective magnetic field. We show that the OSCAR technique provides continuous monitoring of the single spin, which could be used to detect the mysterious quantum collapses of the wave function of the cantilever-spin system.

  1. 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 particular, we find that state preparation using control of the internal hyperfine spin increases the entangling power of squeezing protocols when f >1/2. Post-processing of the ensemble using additional internal spin control converts this entanglement into metrologically useful spin squeezing. By employing a variation of the Holstein-Primakoff approximation, in which the collective spin observables of the atomic ensemble are treated as quadratures of a bosonic mode, we model entanglement generation, spin squeezing and the effects of internal spin control. The Holstein-Primakoff formalism also enables us to take into account the decoherence of the ensemble due to optical pumping. While most works ignore or treat optical pumping phenomenologically, we employ a master equation derived from first principles. Our analysis shows that state preparation and the hyperfine spin size have a substantial impact upon both the generation of spin squeezing and the decoherence of the ensemble. Through a numerical search, we determine state preparations that enhance squeezing protocols while remaining robust to optical pumping. Finally, most work on spin squeezing in atomic ensembles has treated the light as a plane wave that couples identically to all atoms. In the final part of this dissertation, we go beyond the customary plane wave approximation on the light and employ focused paraxial beams, which are more efficiently mode matched to the radiation pattern of the atomic ensemble. The mathematical formalism and the internal spin control techniques that we applied in the plane wave case are generalized to accommodate the non-homogeneous paraxial probe. We find the optimal geometries of the atomic ensemble and the probe for mode matching and generation of spin squeezing.

  2. 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 particular, we find that state preparation using control of the internal hyperfine spin increases the entangling power of squeezing protocols when f>1/2. Post-processing of the ensemble using additional internal spin control converts this entanglement into metrologically useful spin squeezing. By employing a variation of the Holstein-Primakoff approximation, in which the collective spin observables of the atomic ensemble are treated as quadratures of a bosonic mode, we model entanglement generation, spin squeezing and the effects of internal spin control. The Holstein-Primakoff formalism also enables us to take into account the decoherence of the ensemble due to optical pumping. While most works ignore or treat optical pumping phenomenologically, we employ a master equation derived from first principles. Our analysis shows that state preparation and the hyperfine spin size have a substantial impact upon both the generation of spin squeezing and the decoherence of the ensemble. Through a numerical search, we determine state preparations that enhance squeezing protocols while remaining robust to optical pumping. Finally, most work on spin squeezing in atomic ensembles has treated the light as a plane wave that couples identically to all atoms. In the final part of this dissertation, we go beyond the customary plane wave approximation on the light and employ focused paraxial beams, which are more efficiently mode matched to the radiation pattern of the atomic ensemble. The mathematical formalism and the internal spin control techniques that we applied in the plane wave case are generalized to accommodate the non-homogeneous paraxial probe. We find the optimal geometries of the atomic ensemble and the probe for mode matching and generation of spin squeezing.

  3. Single-shot readout of multiple nuclear spin qubits in diamond under ambient conditions.

    PubMed

    Drau, A; Spinicelli, P; Maze, J R; Roch, J-F; Jacques, V

    2013-02-01

    We use the electronic spin of a single nitrogen-vacancy defect in diamond to observe the real-time evolution of neighboring single nuclear spins under ambient conditions. Using a diamond sample with a natural abundance of (13)C isotopes, we first demonstrate high fidelity initialization and single-shot readout of an individual (13)C nuclear spin. By including the intrinsic (14)N nuclear spin of the nitrogen-vacancy defect in the quantum register, we then report the simultaneous observation of quantum jumps linked to both nuclear spin species, providing an efficient initialization of the two qubits. These results open up new avenues for diamond-based quantum information processing including active feedback in quantum error correction protocols and tests of quantum correlations with solid-state single spins at room temperature. PMID:23432227

  4. Kondo effect of molecular complexes at surfaces: ligand control of the local spin coupling.

    PubMed

    Wahl, P; Diekhner, L; Wittich, G; Vitali, L; Schneider, M A; Kern, K

    2005-10-14

    The spin state of single magnetic atoms and molecules at surfaces is of fundamental interest and may play an important role in future atomic-scale technologies. We demonstrate the ability to tune the coupling between the spin of individual cobalt adatoms with their surroundings by controlled attachment of molecular ligands. The strength of the coupling is determined via the Kondo resonance by low-temperature scanning tunneling spectroscopy. Spatial Kondo resonance mapping is introduced as a novel imaging tool to localize spin centers in magnetic molecules with atomic precision. PMID:16241825

  5. Feedback control of noise in spin valves by the spin-transfer torque

    NASA Astrophysics Data System (ADS)

    Bandopadhyay, Swarnali; Brataas, Arne; Bauer, Gerrit E. W.

    2011-02-01

    The miniaturization of magnetic read heads and random access memory elements makes them vulnerable to thermal fluctuations. We demonstrate how current-induced spin-transfer torques can be used to suppress the effects of thermal fluctuations. This enhances the fidelity of perpendicular magnetic spin valves. The simplest realization is a dc to stabilize the free magnetic layers. The power can be significantly reduced without losing fidelity by simple control schemes, in which the stabilizing current-induced spin-transfer torque is controlled by the instantaneous resistance.

  6. 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.

  7. Efficient spin filter and spin valve in a single-molecule magnet Fe4 between two graphene electrodes

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    We propose a magnetic molecular junction consisting of a single-molecule magnet Fe4 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.

  8. All-optical control of a solid-state spin using coherent dark states

    PubMed Central

    Yale, Christopher G.; Buckley, Bob B.; Christle, David J.; Burkard, Guido; Heremans, F. Joseph; Bassett, Lee C.; Awschalom, David D.

    2013-01-01

    The study of individual quantum systems in solids, for use as quantum bits (qubits) and probes of decoherence, requires protocols for their initialization, unitary manipulation, and readout. In many solid-state quantum systems, these operations rely on disparate techniques that can vary widely depending on the particular qubit structure. One such qubit, the nitrogen-vacancy (NV) center spin in diamond, can be initialized and read out through its special spin-selective intersystem crossing, while microwave electron spin resonance techniques provide unitary spin rotations. Instead, we demonstrate an alternative, fully optical approach to these control protocols in an NV center that does not rely on its intersystem crossing. By tuning an NV center to an excited-state spin anticrossing at cryogenic temperatures, we use coherent population trapping and stimulated Raman techniques to realize initialization, readout, and unitary manipulation of a single spin. Each of these techniques can be performed directly along any arbitrarily chosen quantum basis, removing the need for extra control steps to map the spin to and from a preferred basis. Combining these protocols, we perform measurements of the NV centers spin coherence, a demonstration of this full optical control. Consisting solely of optical pulses, these techniques enable control within a smaller footprint and within photonic networks. Likewise, this unified approach obviates the need for both electron spin resonance manipulation and spin addressability through the intersystem crossing. This method could therefore be applied to a wide range of potential solid-state qubits, including those which currently lack a means to be addressed. PMID:23610403

  9. Controllable generation of a spin-triplet supercurrent in a Josephson spin valve

    NASA Astrophysics Data System (ADS)

    Iovan, Adrian; Golod, Taras; Krasnov, Vladimir M.

    2014-10-01

    It has been predicted theoretically that an unconventional odd-frequency spin-triplet component of a superconducting order parameter can be induced in multilayered ferromagnetic structures with noncollinear magnetization. In this work, we study experimentally nanoscale devices, in which a ferromagnetic spin valve is embedded into a Josephson junction. We demonstrate two ways of in situ analysis of such Josephson spin valves: via magnetoresistance measurements and via in situ magnetometry based on flux quantization in the junction. We observe that supercurrent through the device depends on the relative orientation of magnetizations of the two ferromagnetic layers and is enhanced in the noncollinear state of the spin valve. We attribute this phenomenon to controllable generation of the spin-triplet superconducting component in a ferromagnet.

  10. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

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

    PubMed

    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

  13. Spin vector control of a spinning space station

    NASA Technical Reports Server (NTRS)

    Hendricks, T.

    1971-01-01

    Digital computer program simulates system and related functions. Program is intended for, but not limited to, altitude control studies of rotating space station. Russel's method of formulating and solving motion equations for system of rigid bodies connected by movable joints is applied. Program features are listed.

  14. 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

  15. Protein imaging. Single-protein spin resonance spectroscopy under ambient conditions.

    PubMed

    Shi, Fazhan; Zhang, Qi; Wang, Pengfei; Sun, Hongbin; Wang, Jiarong; Rong, Xing; Chen, Ming; Ju, Chenyong; Reinhard, Friedemann; Chen, Hongwei; Wrachtrup, Jrg; Wang, Junfeng; Du, Jiangfeng

    2015-03-01

    Magnetic resonance is essential in revealing the structure and dynamics of biomolecules. However, measuring the magnetic resonance spectrum of single biomolecules has remained an elusive goal. We demonstrate the detection of the electron spin resonance signal from a single spin-labeled protein under ambient conditions. As a sensor, we use a single nitrogen vacancy center in bulk diamond in close proximity to the protein. We measure the orientation of the spin label at the protein and detect the impact of protein motion on the spin label dynamics. In addition, we coherently drive the spin at the protein, which is a prerequisite for studies involving polarization of nuclear spins of the protein or detailed structure analysis of the protein itself. PMID:25745170

  16. 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.

  17. Target Single-Spin Asymmetry in Inclusive Hadron Production

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaodong

    2015-02-01

    We present the first measurement of target single-spin asymmetries (AN) in the inclusive hadron production reaction, e+3He? ?h+X, using a transversely polarized 3He target at an electron-nucleon center-of-mass energy ? {s} = 3.45 GeV. The experiment was conducted at Jefferson Lab in Hall A using a 5.9-GeV electron beam. Several types of hadrons (?, K and proton) were detected with an average momentum = 2.35 GeV/c, and an average transverse momentum = 0.64 GeV/c. The observed asymmetry strongly depends on the type of hadron. A positive asymmetry is observed for ?+ and K+. A negative asymmetry is observed for ?-. The ?+ and ?- asymmetries measured for the 3He target and extracted the "effective- neutron" SSA. Amazingly, we found that the ratio of our observed SSA between ?+ and ?- productions closely resemble the ratio of up- to down-quark's contributions to neutron's anomalous magnetic moment.

  18. Theory of transport through noncollinear single-electron spin-valve transistors

    NASA Astrophysics Data System (ADS)

    Lindebaum, Stephan; König, Jürgen

    2011-12-01

    We study the electronic transport through a noncollinear single-electron spin-valve transistor. It consists of a small metallic island weakly coupled to two ferromagnetic leads with noncollinear magnetization directions. The electric current is influenced by Coulomb charging and by spin accumulation. Furthermore, the interplay of Coulomb interaction and tunnel coupling to spin-polarized leads yields a many-body exchange field in which the accumulated island spin precesses. We analyze the effects of this exchange field in both the linear and nonlinear transport regime. In particular, we find that the exchange field can give rise to a high sensitivity of the island's spin orientation on the gate voltage.

  19. Control of exciton spin statistics through spin polarization in organic optoelectronic devices.

    PubMed

    Wang, Jianpu; Chepelianskii, Alexei; Gao, Feng; Greenham, Neil C

    2012-01-01

    Spintronics based on organic semiconductor materials is attractive because of its rich fundamental physics and potential for device applications. Manipulating spins is obviously important for spintronics, and is usually achieved by using magnetic electrodes. Here we show a new approach where spin populations can be controlled primarily by energetics rather than kinetics. We find that exciton spin statistics can be substantially controlled by spin-polarizing carriers after injection using high magnetic fields and low temperatures, where the Zeeman energy is comparable with the thermal energy. By using this method, we demonstrate that singlet exciton formation can be suppressed by up to 53% in organic light-emitting diodes, and the dark conductance of organic photovoltaic devices can be increased by up to 45% due to enhanced formation of triplet charge-transfer states, leading to less recombination to the ground state. PMID:23149736

  20. 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.

  1. 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

  2. Realization of Quantum Integer-Spin Chains with Controllable Interactions

    NASA Astrophysics Data System (ADS)

    Richerme, Philip; Senko, Crystal; Smith, Jacob; Lee, Aaron; Cohen, Itsik; Retzker, Alex; Monroe, Chris

    2015-05-01

    The physics of interacting integer-spin chains has been a topic of intense theoretical interest, particularly in the context of symmetry-protected topological phases. However, there has not been a controllable model system to study this physics experimentally. We demonstrate how spin-dependent laser forces on trapped 171Yb+ ions can be used to engineer an effective system of interacting spin-1 particles. Our system evolves coherently under an applied spin-1 XY Hamiltonian with tunable, long-range couplings, and all three quantum levels at each site participate in the dynamics. This experimental platform enables future studies of symmetry-protected order in spin-1 systems and their use in quantum applications. This work is supported by the ARO Atomic Physics Program, the AFOSR MURI on Quantum Measurement and Verification, and the NSF Physics Frontier Center at JQI.

  3. 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.

  4. Spin-transfer torque based damping control of parametrically excited spin waves in a magnetic insulator

    NASA Astrophysics Data System (ADS)

    Lauer, V.; Bozhko, D. A.; Brcher, T.; Pirro, P.; Vasyuchka, V. I.; Serga, A. A.; Jungfleisch, M. B.; Agrawal, M.; Kobljanskyj, Yu. V.; Melkov, G. A.; Dubs, C.; Hillebrands, B.; Chumak, A. V.

    2016-01-01

    The damping of spin waves parametrically excited in the magnetic insulator Yttrium Iron Garnet (YIG) is controlled by a dc current passed through an adjacent normal-metal film. The experiment is performed on a macroscopically sized YIG(100 nm)/Pt(10 nm) bilayer of 4 2 mm2 lateral dimensions. The spin-wave relaxation frequency is determined via the threshold of the parametric instability measured by Brillouin light scattering spectroscopy. The application of a dc current to the Pt film leads to the formation of a spin-polarized electron current normal to the film plane due to the spin Hall effect. This spin current exerts a spin transfer torque in the YIG film and, thus, changes the spin-wave damping. Depending on the polarity of the applied dc current with respect to the magnetization direction, the damping can be increased or decreased. The magnitude of its variation is proportional to the applied current. A variation in the relaxation frequency of 7.5 % is achieved for an applied dc current density of 5 1010 A/m2.

  5. Spin-controlled vertical cavity surface-emitting lasers

    NASA Astrophysics Data System (ADS)

    Hövel, Stephan; Gerhardt, Nils C.; Brenner, Carsten; Hofmann, Martin R.; Lo, Fang-Yuh; Reuter, Dirk; Wieck, Andreas D.; Schuster, Ellen; Keune, Werner

    2006-04-01

    The output polarization of an optically pumped InGaAs/GaAs vertical cavity surface-emitting laser (VCSEL) is analyzed at room temperature as a function of the circular input polarization degree. The emission of the VCSEL is unambiguously controlled by the exciting polarization and only 30% of spin-polarized electrons are needed in the active region to generate an output polarization degree of up to 100% at short-pulsed pumping. This testifies that a VCSEL can be used as an effective amplifier for spin information even at room temperature. Measurements with a continuous wave excitation were executed to demonstrate the possibility of spin-amplification by electrical spin-injection in a VCSEL. All measurements were confirmed by a phenomenological spin flip model. Our paper is completed with the introduction of Fe/Tb-Multilayers used for spin injection. These contacts enable spin injection without external magnetic fields, i.e. in remanence. Finally, we suggest a combination of these multilayers with a VCSEL-structure to create the first spin-optoelectronic device working both at room temperature and without external fields.

  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. 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

  8. 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

  9. 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.

  10. 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.

  11. Dissipative Quantum Control of a Spin Chain

    NASA Astrophysics Data System (ADS)

    Morigi, Giovanna; Eschner, Jürgen; Cormick, Cecilia; Lin, Yiheng; Leibfried, Dietrich; Wineland, David J.

    2015-11-01

    A protocol is discussed for preparing a spin chain in a generic many-body state in the asymptotic limit of tailored nonunitary dynamics. The dynamics require the spectral resolution of the target state, optimized coherent pulses, engineered dissipation, and feedback. As an example, we discuss the preparation of an entangled antiferromagnetic state, and argue that the procedure can be applied to chains of trapped ions or Rydberg atoms.

  12. Berry phase magnetometry using a single electronic spin in diamond

    NASA Astrophysics Data System (ADS)

    Arai, Keigo; Lee, Junghyun; Belthangady, Chinmay; Walsworth, Ronald

    2015-05-01

    We present a new approach for improving the sensitivity and dynamic-range of nitrogen-vacancy (NV) center magnetic field sensing using Berry phase. In the conventional Ramsey interferometry, an NV spin accumulates dynamic phase proportional to the Larmor frequency. This approach provides high sensitivity in exchange for the dynamic-range due to 2pi phase ambiguity. Our approach, in which the magnetic field is encoded in the Berry phase of the spin, can unwrap this ambiguity due to a chirped magnetometry curve. This work will provide a new modality not only for magnetometry but also for thermometry and electrometry using solid-state spins.

  13. Dual Control of Giant Field-like Spin Torque in Spin Filter Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Tang, Y.-H.; Chu, F.-C.; Kioussis, Nicholas

    2015-06-01

    We predict a giant field-like spin torque, , in spin-filter (SF) barrier tunnel junctions in sharp contrast to existing junctions based on nonmagnetic passive barriers. We demonstrate that has linear bias behavior, is independent of the SF thickness, and has odd parity with respect to the SFs exchange splitting. Thus, it can be selectively controlled via external bias or external magnetic field which gives rise to sign reversal of via magnetic field switching. The underlying mechanism is the interlayer exchange coupling between the noncollinear magnetizations of the SF and free ferromagnetic electrode via the nonmagnetic insulating (I) spacer giving rise to giant spin-dependent reflection at the SF/I interface. These findings suggest that the proposed field-like-spin-torque MRAM may provide promising dual functionalities for both reading and writing processes which require lower critical current densities and faster writing and reading speeds.

  14. Dual Control of Giant Field-like Spin Torque in Spin Filter Tunnel Junctions

    PubMed Central

    Tang, Y. -H.; Chu, F. -C.; Kioussis, Nicholas

    2015-01-01

    We predict a giant field-like spin torque, , in spin-filter (SF) barrier tunnel junctions in sharp contrast to existing junctions based on nonmagnetic passive barriers. We demonstrate that has linear bias behavior, is independent of the SF thickness, and has odd parity with respect to the SF’s exchange splitting. Thus, it can be selectively controlled via external bias or external magnetic field which gives rise to sign reversal of via magnetic field switching. The underlying mechanism is the interlayer exchange coupling between the noncollinear magnetizations of the SF and free ferromagnetic electrode via the nonmagnetic insulating (I) spacer giving rise to giant spin-dependent reflection at the SF/I interface. These findings suggest that the proposed field-like-spin-torque MRAM may provide promising dual functionalities for both ‘reading’ and ‘writing’ processes which require lower critical current densities and faster writing and reading speeds. PMID:26095146

  15. Single-transverse spin asymmetry in dijet correlations at hadron colliders

    SciTech Connect

    Bomhof, C. J.; Mulders, P. J.; Vogelsang, W.; Yuan, F.

    2007-04-01

    We present a phenomenological study of the single-transverse spin asymmetry in azimuthal correlations of two jets produced nearly 'back-to-back' in pp collisions at RHIC. We properly take into account the initial- and final-state interactions of partons that can generate this asymmetry in QCD hard-scattering. Using distribution functions fitted to the existing single-spin data, we make predictions for various weighted single-spin asymmetries in dijet correlations that are now readily testable at RHIC.

  16. Gate-voltage controlled spin pumping effects: spin injection from YIG and Co into metal and graphene based 2 D materials

    NASA Astrophysics Data System (ADS)

    Kalitsov, Alan; Chshiev, Mairbek; Mryasov, Oleg

    2015-03-01

    Spin current injection into nonmagnetic metals, semiconductors and oxides is crucial component of spintronics. The spin pumping mechanism free from the impedance mismatch is a promising way to inject spin current into nonmagnetic materials. Here we present theory of spin current injected into non-magnetic films which arises from magnetization precession. We apply this theory to two cases (i) insulating yttrium iron garnet ferromagnet/nonmagnetic metal interfaces and (ii) hcp-Co/single layer graphene interface. The electron transport calculations are based on the non-equilibrium Green Function formalism within the tight binding Hamiltonian model. We show that magnitude of the pumped spin current can be efficiently controlled by the gate voltage.

  17. Decoherence of a single spin coupled to an interacting spin bath

    NASA Astrophysics Data System (ADS)

    Wu, Ning; Fröhling, Nina; Xing, Xi; Hackmann, Johannes; Nanduri, Arun; Anders, Frithjof B.; Rabitz, Herschel

    2016-01-01

    Decoherence of a central spin coupled to an interacting spin bath via inhomogeneous Heisenberg coupling is studied by two different approaches, namely an exact equations of motion (EOMs) method and a Chebyshev expansion technique (CET). By assuming a wheel topology of the bath spins with uniform nearest-neighbor X X -type intrabath coupling, we examine the central spin dynamics with the bath prepared in two different types of bath initial conditions. For fully polarized baths in strong magnetic fields, the polarization dynamics of the central spin exhibits a collapse-revival behavior in the intermediate-time regime. Under an antiferromagnetic bath initial condition, the two methods give excellently consistent central spin decoherence dynamics for finite-size baths of N ≤14 bath spins. The decoherence factor is found to drop off abruptly on a short time scale and approach a finite plateau value which depends on the intrabath coupling strength nonmonotonically. In the ultrastrong intrabath coupling regime, the plateau values show an oscillatory behavior depending on whether N /2 is even or odd. The observed results are interpreted qualitatively within the framework of the EOM and perturbation analysis. The effects of anisotropic spin-bath coupling and inhomogeneous intrabath bath couplings are briefly discussed. Possible experimental realization of the model in a modified quantum corral setup is suggested.

  18. 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.

  19. Spin relaxometry of single nitrogen-vacancy defects in diamond nanocrystals for magnetic noise sensing

    NASA Astrophysics Data System (ADS)

    Tetienne, J.-P.; Hingant, T.; Rondin, L.; Cavaills, A.; Mayer, L.; Dantelle, G.; Gacoin, T.; Wrachtrup, J.; Roch, J.-F.; Jacques, V.

    2013-06-01

    We report an experimental study of the longitudinal relaxation time (T1) of the electron spin associated with single nitrogen-vacancy (NV) defects hosted in nanodiamonds (NDs). We first show that T1 decreases over three orders of magnitude when the ND size is reduced from 100 to 10 nm owing to the interaction of the NV electron spin with a bath of paramagnetic centers lying on the ND surface. We next tune the magnetic environment by decorating the ND surface with Gd3+ ions and observe an efficient T1 quenching, which demonstrates magnetic noise sensing with a single electron spin. We estimate a sensitivity down to ?14 electron spins detected within 10 s, using a single NV defect hosted in a 10-nm-size ND. These results pave the way towards T1-based nanoscale imaging of the spin density in biological samples.

  20. Noise-resistant optimal spin squeezing via quantum control

    NASA Astrophysics Data System (ADS)

    Pichler, T.; Caneva, T.; Montangero, S.; Lukin, M. D.; Calarco, T.

    2016-01-01

    Entangled atomic states, such as spin-squeezed states, represent a promising resource for a new generation of quantum sensors and atomic clocks. We demonstrate that optimal control techniques can be used to substantially enhance the degree of spin squeezing in strongly interacting many-body systems, even in the presence of noise and imperfections. Specifically, we present a protocol that is robust to noise and outperforms conventional methods. Potential experimental implementations are discussed.

  1. 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.

  2. Microscopic control of 29Si nuclear spins near phosphorus donors in silicon

    NASA Astrophysics Data System (ADS)

    Jrvinen, J.; Zvezdov, D.; Ahokas, J.; Sheludyakov, S.; Vainio, O.; Lehtonen, L.; Vasiliev, S.; Fujii, Y.; Mitsudo, S.; Mizusaki, T.; Gwak, M.; Lee, SangGap; Lee, Soonchil; Vlasenko, L.

    2015-09-01

    We demonstrate an efficient control of 29Si nuclear spins for specific lattice sites near 31P donors in silicon at temperatures below 1 K and in a high magnetic field of 4.6 T. Excitation of the forbidden electron-nuclear transitions leads to a pattern of well-resolved holes and peaks in the electron spin resonance (ESR) lines of 31P . The pattern originates from dynamic polarization (DNP) of the 29Si nuclear spins near the donors via the solid effect. DNP of 29Si is demonstrated also with the Overhauser effect where the allowed ESR transitions are excited. In this case mostly the remote 29Si nuclei having weak interaction with the donors are polarized, which results in a single hole and a sharp peak pair in the ESR spectrum. Our work shows that the solid effect can be used for initialization of 29Si nuclear spin qubits near the donors.

  3. 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.

  4. 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.

  5. 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.

  6. Floquet control of quantum dissipation in spin chains

    NASA Astrophysics Data System (ADS)

    Chen, Chong; An, Jun-Hong; Luo, Hong-Gang; Sun, C. P.; Oh, C. H.

    2015-05-01

    Controlling the decoherence induced by the interaction of quantum system with its environment is a fundamental challenge in quantum technology. Utilizing Floquet theory, we explore the constructive role of temporal periodic driving in suppressing decoherence of a spin-1/2 particle coupled to a spin bath. It is revealed that, accompanying the formation of a Floquet bound state in the quasienergy spectrum of the whole system including the system and its environment, the dissipation of the spin system can be inhibited and the system tends to coherently synchronize with the driving. It can be seen as an analog to the decoherence suppression induced by the structured environment in spatially periodic photonic crystal setting. Comparing with other decoherence control schemes, our protocol is robust against the fluctuation of control parameters and easy to realize in practice. It suggests a promising perspective of periodic driving in decoherence control.

  7. Ultrafast optical coherent control of individual electron and hole spins in a semiconductor quantum dot

    NASA Astrophysics Data System (ADS)

    de Greve, Kristiaan

    2012-02-01

    We report on the complete optical coherent control of individual electron and hole spin qubits in InAs quantum dots. With a magnetic field in Voigt geometry, broadband, detuned optical pulses couple the spin-split ground states, resulting in Rabi flopping. In combination with the Larmor precession around the external magnetic field, this allows an arbitrary single-qubit operation to be realized in less than 20 picoseconds [1,2]. Slow fluctuations in the spin's environment lead to shot-to-shot variations in the Larmor precession frequency. In a time-ensemble measurement, these would prevent a measurement of the true decoherence of the qubit, and instead give rise to ensemble dephasing. This effect was overcome by implementing a spin echo measurement scheme for both electron and hole spins, where an optical ?-pulse refocuses the spin coherence and filters out the slow variations in Larmor precession frequency. We measured coherence times up to 3 microseconds [2,3]. Finally, our optical pulse manipulation scheme allows us to probe the hyperfine interaction between the single spin and the nuclei in the quantum dot. Interesting non-Markovian dynamics could be observed in the free-induction decay of a single electron spin, whereas the complete absence of such effects illustrates the reduction of the hyperfine interaction for hole spin qubits. We measured and modeled these effects, and explain the non-Markovian electron spin dynamics as involving a feedback effect resulting from both the strong Overhauser shift of the electron spin and spin dependent nuclear relaxation [2,4]. [4pt] [1] D. Press, T. D. Ladd, B. Zhang and Y. Yamamoto, Nature 456, 218 (2008)[0pt] [2] K. De Greve, P. McMahon, D. Press et al., Nat. Phys. 7, 872 (2011)[0pt] [3] D. Press, K. De Greve, P. McMahon et al., Nat. Phot. 4, 367 (2010)[0pt] [4] T. D. Ladd, D. Press, K. De Greve et al., Phys. Rev. Lett. 105, 107401 (2010)

  8. Galileo dual-spin attitude and articulation control system

    NASA Technical Reports Server (NTRS)

    Ward, R. S.

    1978-01-01

    Galileo, the first outer planet explorer to be configured as a dual spinner, will conduct intensive investigation of Jupiter's atmosphere, satellites, and magnetosphere. The exacting mission, coupled with the inherently complex spin and flexible body dynamics of the vehicle, demands careful design of the Galileo Attitude and Articulation Control System (AACS). A brief overview of the Galileo mission and spacecraft is presented, followed by a detailed discussion on the mechanization of the AACS and the many factors that influence its design. Included are discussions on attitude determination and control, high-gain antenna pointing, science scan platform pointing, nutation damping, wobble compensation, spin and despin control, and propellant migration and boom flexibility effects.

  9. Optical Control of Semiconductor Quantum Dot Spin Qubits with Microcavity Exciton-Polaritons

    NASA Astrophysics Data System (ADS)

    Puri, Shruti; McMahon, Peter L.; Yamamoto, Yoshihisa

    2015-03-01

    Topological surface codes demand the least stringent threshold conditions and are most promising for implementing large quantum algorithms. Based on the resource requirements to reach fault tolerance, we develop a hardware platform for large scale quantum computation with semiconductor quantum dot (QD) electron spin qubits. The current proposals for implementation of two-qubit gates and quantum non demolition (QND) readout in a QuDOS (Quantum Dots with Optically Controlled Spins) architecture suffer from large error rates. In our scheme, the optical manipulation of the QD spin qubits is carried out using their Coulomb exchange interaction with optically excited, spin-polarized, laterally confined quantum well (LcQW) exciton-polaritons. The small mass of polaritons protects them from interaction with their solid-state environment (phonons) and enables strong coupling between spin qubits separated by a few microns. Furthermore, the excitation manifold of the QD is well separated from that of the LcQW polaritons, preventing a spin-flip event during readout. We will outline schemes for implementing fast, high-fidelity, single qubit gate, two-qubit geometric phase gate and single-shot QND measurement and analyze important decoherence mechanisms. The work being presented was carried out at Stanford University. Currently the author is at University of Sherbrooke, Canada.

  10. Theory of single nuclear spin detection in magnetic resonance force microscopy

    NASA Astrophysics Data System (ADS)

    Chemudupati, Srinivasa; Tsifrinovich, Vladimir

    2008-10-01

    We develop a theory for the measurement of a nuclear spin state in a paramagnetic atom with Oscillating Cantilever-Driven Adiabatic Reversals (OSCAR) in Magnetic Resonance Force Microscopy (MRFM). In this theory, we use a semi-classical approach where the electron-nuclear spin system, with hyperfine interaction, is treated quantum mechanically and the motion of the ferromagnetic particle on the cantilever tip is treated classically. Our computations support the idea of the measurement of a nuclear spin state by detection of a single electron spin.

  11. 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.

  12. Fast Room-Temperature Phase Gate on a Single Nuclear Spin in Diamond

    NASA Astrophysics Data System (ADS)

    Sangtawesin, S.; Brundage, T. O.; Petta, J. R.

    2015-03-01

    Nuclear spins support long lived quantum coherence due to weak coupling to the environment, but are difficult to rapidly control using nuclear magnetic resonance as a result of the small nuclear magnetic moment. We demonstrate a fast ~ 500 ns nuclear spin phase gate on a 14N nuclear spin qubit intrinsic to a nitrogen-vacancy center in high purity diamond. This phase gate is achieved by utilizing electron-nuclear hyperfine interaction. By driving off-resonant Rabi oscillations on the electronic spin, we can generate an arbitrary phase gate on the nuclear spin. We also demonstrate that repeated applications of ?-phase gates can bang-bang decouple the nuclear spin from the environment, locking the spin state for up to 140 ?s. Research was supported by the Sloan and Packard Foundations, the National Science Foundation through Awards DMR-0819860 and DMR-0846341, and the Army Research Office through PECASE Award W911NF-08-1-0189.

  13. Spin transport properties of single metallocene molecules attached to single-walled carbon nanotubes via nickel adatoms

    NASA Astrophysics Data System (ADS)

    Wei, Peng; Sun, Lili; Benassi, Enrico; Shen, Ziyong; Sanvito, Stefano; Hou, Shimin

    2011-06-01

    The spin-dependent transport properties of single ferrocene, cobaltocene, and nickelocene molecules attached to the sidewall of a (4,4) armchair single-walled carbon nanotube via a Ni adatom are investigated by using a self-consistent ab initio approach that combines the non-equilibrium Green's function formalism with the spin density functional theory. Our calculations show that the Ni adatom not only binds strongly to the sidewall of the nanotube, but also maintains the spin degeneracy and affects little the transmission around the Fermi level. When the Ni adatom further binds to a metallocene molecule, its density of states is modulated by that of the molecule and electron scattering takes place in the nanotube. In particular, we find that for both cobaltocene and nickelocene the transport across the nanotube becomes spin-polarized. This demonstrates that metallocene molecules and carbon nanotubes can become a promising materials platform for applications in molecular spintronics.

  14. Optimal and suboptimal control technique for aircraft spin recovery

    NASA Technical Reports Server (NTRS)

    Young, J. W.

    1974-01-01

    An analytic investigation has been made of procedures for effecting recovery from equilibrium spin conditions for three assumed aircraft configurations. Three approaches which utilize conventional aerodynamic controls are investigated. Included are a constant control recovery mode, optimal recoveries, and a suboptimal control logic patterned after optimal recovery results. The optimal and suboptimal techniques are shown to yield a significant improvement in recovery performance over that attained by using a constant control recovery procedure.

  15. Magnetic interaction between a radical spin and a single-molecule magnet in a molecular spin-valve.

    PubMed

    Urdampilleta, Matias; Klayatskaya, Svetlana; Ruben, Mario; Wernsdorfer, Wolfgang

    2015-04-28

    Molecular spintronics using single molecule magnets (SMMs) is a fast growing field of nanoscience that proposes to manipulate the magnetic and quantum information stored in these molecules. Herein we report evidence of a strong magnetic coupling between a metallic ion and a radical spin in one of the most extensively studied SMMs: the bis(phtalocyaninato)terbium(III) complex (TbPc2). For that we use an original multiterminal device comprising a carbon nanotube laterally coupled to the SMMs. The current through the device, sensitive to magnetic interactions, is used to probe the magnetization of a single Tb ion. Combining this electronic read-out with the transverse field technique has allowed us to measure the interaction between the terbium ion, its nuclear spin, and a single electron located on the phtalocyanine ligands. We show that the coupling between the Tb and this radical is strong enough to give extra resonances in the hysteresis loop that are not observed in the anionic form of the complex. The experimental results are then modeled by diagonalization of a three-spins Hamiltonian. This strong coupling offers perspectives for implementing nuclear and electron spin resonance techniques to perform basic quantum operations in TbPc2. PMID:25858088

  16. Controlled coupling of spin-resolved quantum Hall edge states

    NASA Astrophysics Data System (ADS)

    Karmakar, Biswajit

    2012-02-01

    Spin resolved edge states in quantum Hall systems at filling fraction ? = 2 posses large coherence [1] and relaxation [2] lengths. They are ideal candidates for the implementation of dual-rail quantum computation architectures [3] by encoding the qubit in the spin degree of freedom of the co-propagating spin resolved edge states. An important element for realization of such architectures is a coherent beam splitter that controllably mixes the two co-propagating spin-resolved edge channels to create any superposition of the two logic states. In this talk we demonstrate a new method to controllably couple spin resolved edge states and induce inter-edge charge transfer associated to spin-flip scattering events [4]. The process exploits the coupling of the electron spin with a spatially-dependent periodic in-plane magnetic field that is created by an array of Cobalt nano-magnets placed at the boundary of the GaAs/AlGaAs modulation doped heterostructure. The maximum charge/spin transfer of 28 1 % is achieved at 250 mK by fine tuning the perpendicular magnetic field. These results are key steps towards the realization of a scalable quantum interferometric device currently under investigation in our group. [4pt] [1] Y. Ji et al. Nature 422 (2003) 415.[0pt] [2] G. Muller et al. Phy. Rev. B 45 (1992) 3932.[0pt] [3] V. Giovannetti et al., Phys. Rev. B 77 (2008) 155320.[0pt] [4] B. Karmakar et al., (accepted in PRL).

  17. Single-spin microscope with sub-nanoscale resolution based on optically detected magnetic resonance

    NASA Astrophysics Data System (ADS)

    Berman, Gennady P.; Chernobrod, Boris M.

    2010-01-01

    Recently we proposed a new approach which potentially has single spin sensitivity, sub-nanometer spatial resolution, and ability to operate at room temperature (J. Appl. Phys. 97, 014903 (2005); U.S. Patent No. 7,305,869, 2007). In our approach a nanoscale photoluminescent center exhibits optically detected magnetic resonance (ODMR) in the vicinity of magnetic moment in the sample related with unpaired individual electron or nuclear spins, or ensemble of spins. We consider as a sensor material that exhibit ODMR properties nitrogen-vacancy (N-V) centers in diamond. N-V centers in diamond has serious advantage having extraordinary chemical and photostability, very long spin lifetimes, and ability single-spin detection at room temperature. The variety of possible scanning schemes has been considered. The potential application to 3D imaging of biological structure has been analyzed.

  18. 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.

  19. Spin-phonon coupling in single Mn-doped CdTe quantum dot

    NASA Astrophysics Data System (ADS)

    Cao, C. L.; Besombes, L.; Fernández-Rossier, J.

    2011-11-01

    The spin dynamics of a single Mn atom in a laser driven CdTe quantum dot is addressed theoretically. Recent experimental results [Gall , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.102.127402 102, 127402 (2009); Goryca , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.103.087401 103, 087401 (2009); Gall , Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.81.245315 81, 245315 (2010)] show that it is possible to induce Mn spin polarization by means of circularly polarized optical pumping. Pumping is made possible by the faster Mn spin relaxation in the presence of the exciton. Here we discuss different Mn spin-relaxation mechanisms: first, Mn-phonon coupling, which is enhanced in the presence of the exciton; second, phonon induced hole spin relaxation combined with carrier-Mn spin-flip coupling and photon emission results in Mn spin relaxation. We model the Mn spin dynamics under the influence of a pumping laser that injects excitons into the dot, taking into account exciton-Mn exchange and phonon induced spin relaxation of both Mn and holes. Our simulations account for the optically induced Mn spin pumping.

  20. Optoelectronic Control of Spin and Pseudospin in Layered WSe2

    NASA Astrophysics Data System (ADS)

    Jones, Aaron

    2014-03-01

    Coherent manipulation of spin-like quantum numbers facilitates the development of new quantum technologies. Layered transition metal dichalcogenides provide an ideal laboratory to exploit such dynamic control of spin, pseudospin, and their interplay. Here, we discuss two examples based on monolayer and bilayer WSe2. Due to the inversion asymmetry in monolayer WSe2, valley pseudospins, which index the degenerate extrema of the energy-momentum bands, possess circularly polarized optical selection rules. In addition to the generation of valley polarization through optical pumping of valley excitons, we demonstrate the creation of a coherent superposition between valley states in monolayer WSe2 by linearly polarized excitation. On the other hand, bilayer WSe2 provides an additional quantum degree of freedom, the layer pseudospin, which corresponds to layer polarization. In AB stacked bilayers, we find the real spin is locked to layer pseudospin for a given valley, which results in the suppression of spin relaxation and electrical control of spin Zeeman splitting without an applied magnetic field. Additionally, we obtain spectroscopic evidence of interlayer and intralayer trion species, an important step toward coherent optical control in van der Waals 2D heterostructures. Aaron Jones partially supported by NSF Grant No. DGE-0718124.

  1. Control of the spin geometric phase in semiconductor quantum rings

    NASA Astrophysics Data System (ADS)

    Nagasawa, Fumiya; Frustaglia, Diego; Saarikoski, Henri; Richter, Klaus; Nitta, Junsaku

    2013-09-01

    Since the formulation of the geometric phase by Berry, its relevance has been demonstrated in a large variety of physical systems. However, a geometric phase of the most fundamental spin-1/2 system, the electron spin, has not been observed directly and controlled independently from dynamical phases. Here we report experimental evidence on the manipulation of an electron spin through a purely geometric effect in an InGaAs-based quantum ring with Rashba spin-orbit coupling. By applying an in-plane magnetic field, a phase shift of the Aharonov-Casher interference pattern towards the small spin-orbit-coupling regions is observed. A perturbation theory for a one-dimensional Rashba ring under small in-plane fields reveals that the phase shift originates exclusively from the modulation of a pure geometric-phase component of the electron spin beyond the adiabatic limit, independently from dynamical phases. The phase shift is well reproduced by implementing two independent approaches, that is, perturbation theory and non-perturbative transport simulations.

  2. 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

  3. Imaging single spin probes embedded in a conductive diamagnetic layer.

    SciTech Connect

    Messina, P.; Fradin, F.

    2009-01-01

    The detection of spin noise by means of scanning tunneling microscopy (STM) has recently been substantially improved by the work presented by Komeda and Manassen (Komeda, T.; Manassen, Y. Appl. Phys. Lett. 2008, 92, 212506). The application of this technique to molecular paramagnets requires the positioning and anchoring of paramagnetic molecules at surfaces. It also requires the possibility of tunneling high current densities into the STM-molecule-substrate tunneling junction. In this letter, we exploit the self-assembly of 1,10-phenantroline on the Au(111) surface to form a diamagnetic matrix that hosts individual molecules and dimers of diphenyl-2-picryl-hydrazyl (DPPH). STM measurements are used to characterize the molecular layer. Electron spin resonance (ESR) measurements elucidate the role of thermal annealing in the preservation of the paramagnetic nature of the DPPH molecules.

  4. 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.

  5. 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.

  6. 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

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

    PubMed

    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

    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.

  9. 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.

  10. A brushless dc spin motor for momentum exchange altitude control

    NASA Technical Reports Server (NTRS)

    Stern, D.; Rosenlieb, J. W.

    1972-01-01

    Brushless dc spin motor is designed to use Hall effect probes as means of revolving rotor position and controlling motor winding currents. This results in 3 to 1 reduction in watt-hours required for wheel acceleration, a 2 to 1 reduction in power to run wheel, and a 10 to 1 reduction in the electronics size and weight.

  11. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Controllable Spin Polarization of Charge Current by Rashba Spin Orbital Coupling

    NASA Astrophysics Data System (ADS)

    Cui, Juan; Yang, Yong-Hong; Wang, Jun

    2009-11-01

    We report a theoretic study on modulating the spin polarization of charge current in a mesoscopic four-terminal device of cross structure by using the inverse spin hall effect. The scattering region of device is a two-dimensional electron gas (2DEG) with Rashba spin orbital interaction (RSOI), one of lead is ferromagnetic metal and other three leads are spin-degenerate normal metals. By using Landauer-Bttiker formalism, we found that when a longitudinal charge current flows through 2DEG scattering region from FM lead by external bias, the transverse current can be either a pure spin current or full-polarized charge current due to the combined effect of spin hall effect and its inverse process, and the polarization of this transverse current can be easily controlled by several device parameters such as the Fermi energy, ferromagnetic magnetization, and the RSOI constant. Our method may pave a new way to control the spin polarization of a charge current.

  12. Determination of spin Hamiltonians from projected single reference configuration interaction calculations. I. Spin 1/2 systems.

    PubMed

    Monari, A; Maynau, D; Malrieu, J-P

    2010-07-28

    The most reliable wave-function based treatments of magnetic systems usually start from a complete active space self-consistent field calculation of the magnetic electrons in the magnetic orbitals, followed by extensive and expensive configuration interaction (CI) calculations. This second step, which introduces crucial spin polarization and dynamic correlation effects, is necessary to reach reliable values of the magnetic coupling constants. The computational cost of these approaches increases exponentially with the number of unpaired electrons. The single-determinantal unrestricted density functional Kohn-Sham calculations are computationally much simpler, and may provide reasonable estimates of these quantities, but their results are strongly dependent on the chosen exchange-correlation potential. The present work, which may be seen as an ab initio transcription of the unrestricted density functional theory technique, returns to the perturbative definition of the Heisenberg Hamiltonian as an effective Hamiltonian, and proposes a direct estimate of its diagonal energies through single reference CI calculations. The differences between these diagonal terms actually determine the entire Heisenberg Hamiltonian. The reference determinants must be vectors of the model space and the components on the other vectors of the model space are cancelled along the iterative process. The method is successfully tested on a series of bicentric and multicentric spin 12 systems. The projected single reference difference dedicated CI treatment is both accurate and of moderate cost. It opens the way to parameter-free calculations of large spin assemblies. PMID:20687632

  13. Quantum-state tomography of a single nuclear spin qubit of an optically manipulated ytterbium atom

    SciTech Connect

    Noguchi, Atsushi; Kozuma, Mikio; Eto, Yujiro; Ueda, Masahito

    2011-09-15

    A single Yb atom is loaded into a high-finesse optical cavity with a moving lattice, and its nuclear spin state is manipulated using a nuclear magnetic resonance technique. A highly reliable quantum state control with fidelity and purity greater than 0.98 and 0.96, respectively, is confirmed by the full quantum state tomography; a projective measurement with high speed (500 {mu}s) and high efficiency (0.98) is accomplished using the cavity QED technique. Because a hyperfine coupling is induced only when the projective measurement is operational, the long coherence times (T{sub 1}=0.49 s and T{sub 2}=0.10 s) are maintained.

  14. 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.

  15. All-Optical Initialization, Readout, and Coherent Preparation of Single Silicon-Vacancy Spins in Diamond

    NASA Astrophysics Data System (ADS)

    Rogers, Lachlan J.; Jahnke, Kay D.; Metsch, Mathias H.; Sipahigil, Alp; Binder, Jan M.; Teraji, Tokuyuki; Sumiya, Hitoshi; Isoya, Junichi; Lukin, Mikhail D.; Hemmer, Philip; Jelezko, Fedor

    2014-12-01

    The silicon-vacancy (SiV- ) color center in diamond has attracted attention because of its unique optical properties. It exhibits spectral stability and indistinguishability that facilitate efficient generation of photons capable of demonstrating quantum interference. Here we show optical initialization and readout of electronic spin in a single SiV- center with a spin relaxation time of T1=2.4 ±0.2 ms . Coherent population trapping (CPT) is used to demonstrate coherent preparation of dark superposition states with a spin coherence time of T2⋆=35 ±3 ns . This is fundamentally limited by orbital relaxation, and an understanding of this process opens the way to extend coherence by engineering interactions with phonons. Hyperfine structure is observed in CPT measurements with the Si 29 isotope which allows access to nuclear spin. These results establish the SiV- center as a solid-state spin-photon interface.

  16. 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.

  17. 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.

  18. Spin-dependent negative differential conductance in transport through single-molecule magnets

    NASA Astrophysics Data System (ADS)

    Luo, Wei; Wang, Rui-Qiang; Hu, Liang-Bin; Yang, Mou

    2013-04-01

    Transport properties are theoretically studied through an anisotropy single-molecule magnet symmetrically connected to two identical ferromagnetic leads. It is found that even though in parallel configuration of leads' magnetizations, the total current still greatly depends on the spin polarization of leads at certain particular bias region, and thus for large polarization a prominent negative differential conductance (NDC) emerges. This originates from the joint effect of single-direction transitions and spin polarization, which removes the symmetry between spin-up and spin-down transitions. The present mechanism of NDC is remarkably different from the previously reported mechanisms. To clarify the physics of the NDC, we further monitored the shot noise spectroscopy and found that the appearance of the NDC is accompanied by the rapid decrease of Fano factor.

  19. Single-spin asymmetries in inclusive DIS and in hadronic collisions

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    Transverse single-spin asymmetries in inclusive deep inelastic lepton-nucleon scattering can be generated through multi-photon exchange between the leptonic and the hadronic part of the process. Here we consider two-photon exchange and mainly focus on the transverse target spin asymmetry. In particular, we investigate the case where two photons couple to different quarks. Such a contribution involves a quark-photon-quark correlator in the nucleon, which has a (modeldependent) relation to the Efremov-Teryaev-Qiu-Sterman quark-gluon-quark correlator TF. Using different parameterizations for TF we compute the transverse target spin asymmetries for both a proton and a neutron target and compare the results to recent experimental data. In addition, potential implications for our general understanding of single-spin asymmetries in hard scattering processes are discussed.

  20. Single Spin Asymmetries in Inclusive Dis and Multi-Parton Correlations in the Nucleon

    NASA Astrophysics Data System (ADS)

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

    Transverse single spin asymmetries in inclusive deep-inelastic lepton-nucleon scattering can be generated through multi-photon exchange between the leptonic and the hadronic part of the process. Here we consider two-photon exchange, and mainly focus on the transverse target spin asymmetry. In particular, we investigate the case where two photons couple to different quarks. Such a contribution involves a quark-photon-quark correlator in the nucleon, which has a (model-dependent) relation to the Efremov-Teryaev-Qiu-Sterman quark-gluon-quark correlator TF. Using different parameterizations for TF we compute the transverse target spin asymmetry for both a proton and a neutron target, and compare the results to recent experimental data. Potential implications on our general understanding of single spin asymmetries in hard scattering processes are discussed as well.

  1. Single-spin asymmetries in inclusive deep inelastic scattering and multiparton correlations in the nucleon

    NASA Astrophysics Data System (ADS)

    Metz, A.; Pitonyak, D.; Schfer, A.; Schlegel, M.; Vogelsang, W.; Zhou, J.

    2012-11-01

    Transverse single-spin asymmetries in inclusive deep inelastic lepton-nucleon scattering can be generated through multiphoton exchange between the leptonic and the hadronic part of the process. Here we consider the two-photon exchange and mainly focus on the transverse target spin asymmetry. In particular, we investigate the case where two photons couple to different quarks. Such a contribution involves a quark-photon-quark correlator in the nucleon, which has a (model-dependent) relation to the Efremov-Teryaev-Qiu-Sterman quark-gluon-quark correlator TF. Using different parametrizations for TF we compute the transverse target spin asymmetries for both a proton and a neutron target and compare the results to recent experimental data. In addition, potential implications for our general understanding of single-spin asymmetries in hard scattering processes are discussed.

  2. Realistic Simulations of Single-Spin Measurement via Magnetic Resonance Force Microscopy

    NASA Astrophysics Data System (ADS)

    Brun, Todd A.; Goan, Hsi-Sheng

    2005-10-01

    The problem of measuring single electron or nuclear spins is of great interest for a variety of purposes, from imaging the structure of molecules to quantum information processing. One of the most promising techniques is magnetic resonance force microscopy (MRFM), in which the force between a spin and a small permanent magnet resonantly drives the oscillations of a microcantilever. Numerous issues arise in understanding this system: thermal noise in the cantilever, shot-noise and back-action from monitoring the cantilever's motion, spin relaxation, and interaction with higher cantilever modes. Detailed models of these effects allow one to assess their relative importance and the necessary improvements for sensitivity at the single-spin level.

  3. Spin-pair tunneling in Mn3 single-molecule magnet

    NASA Astrophysics Data System (ADS)

    Li, Yan-Rong; Liu, Rui-Yuan; Wang, Yun-Ping

    2015-10-01

    We report spin-pair tunneling observed in a Mn3 single-molecule magnet, which is a crystal with a two-dimensional network of identical exchange coupling. We observe a series of extra quantum tunnelings by the ac susceptibility measurements, and demonstrate that these are mainly thermally assisted tunnelings of a pair of two spins from the same initial state to the same final state simultaneously. The resonant field of spin-pair tunneling can be expressed as Hz=l D /g ?0?B+(n?-n?) J S /2 g ?0?B , and the splitting interval (|J |S /g ?0?B ) is half that of the single-spin tunneling (2 |J |S /g ?0?B ), which is analogous to the relationship between the magnetic flux quantum in superconductors (h /2 e ) and common metals (h /e ).

  4. 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.

  5. Full control of the spin-wave damping in a magnetic insulator using spin orbit torque

    NASA Astrophysics Data System (ADS)

    Klein, Olivier

    2015-03-01

    The spin-orbit interaction (SOI) has been an interesting and useful addition in the field of spintronics by opening it to non-metallic magnet. It capitalizes on adjoining a strong SOI normal metal next to a thin magnetic layer. The SOI converts a charge current, Jc, into a spin current, Js, with an efficiency parametrized by ΘSH, the spin Hall angle. An important benefit of the SOI is that Jc and Js are linked through a cross-product, allowing a charge current flowing in-plane to produce a spin current flowing out-of-plane. Hence it enables the transfer of spin angular momentum to non-metallic materials and in particular to insulating oxides, which offer improved performance compared to their metallic counterparts. Among all oxides, Yttrium Iron Garnet (YIG) holds a special place for having the lowest known spin-wave (SW) damping factor. Until recently the transmission of spin current through the YIG|Pt interface has been subject to debate. While numerous experiments have reported that Js produced by the excitation of ferromagnetic resonance (FMR) in YIG can cross efficiently the YIG|Pt interface and be converted into Jc in Pt through the inverse spin Hall effect (ISHE), most attempts to observe the reciprocal effect, where Js produced in Pt by the direct spin Hall effect (SHE) is transferred to YIG, resulting in damping compensation, have failed. This has been raising fundamental questions about the reciprocity of the spin transparency of the interface between a metal and a magnetic insulator. In this talk it will be demonstrated that the threshold current for damping compensation can be reached in a 5 μm diameter YIG(20nm)|Pt(7nm) disk. Reduction of both the thickness and lateral size of a YIG-structure were key to reach the microwave generation threshold current, Jc*. The experimental evidence rests upon the measurement of the ferromagnetic resonance linewidth as a function of Idc using a magnetic resonance force microscope (MRFM). It is shwon that the magnetic losses of spin-wave modes existing in the magnetic insulator can be reduced or enhanced by at least a factor of five depending on the polarity and intensity of the in-plane dc current, Idc. Complete compensation of the damping of the fundamental mode by spin-orbit torque is reached for a current density of ~ 3 .1011 A.m-2, in agreement with theoretical predictions. At this critical threshold the MRFM detects a small change of static magnetization, a behavior consistent with the onset of an auto-oscillation regime. This result opens up a new area of research on the electronic control of the damping of YIG-nanostructures.

  6. 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

  7. 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

  8. Flexible coherent control of plasmonic spin-Hall effect

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    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.

  9. Interaction of spin and vibrations in transport through single-molecule magnets

    PubMed Central

    May, Falk; Hofstetter, Walter

    2011-01-01

    Summary We study electron transport through a single-molecule magnet (SMM) and the interplay of its anisotropic spin with quantized vibrational distortions of the molecule. Based on numerical renormalization group calculations we show that, despite the longitudinal anisotropy barrier and small transverse anisotropy, vibrational fluctuations can induce quantum spin-tunneling (QST) and a QST-Kondo effect. The interplay of spin scattering, QST and molecular vibrations can strongly enhance the Kondo effect and induce an anomalous magnetic field dependence of vibrational Kondo side-bands. PMID:22043459

  10. Storage and retrieval of microwave fields at the single-photon level in a spin ensemble

    NASA Astrophysics Data System (ADS)

    Grezes, C.; Julsgaard, B.; Kubo, Y.; Ma, W. L.; Stern, M.; Bienfait, A.; Nakamura, K.; Isoya, J.; Onoda, S.; Ohshima, T.; Jacques, V.; Vion, D.; Esteve, D.; Liu, R. B.; Mlmer, K.; Bertet, P.

    2015-08-01

    We report the storage of microwave pulses at the single-photon level in a spin-ensemble memory consisting of 1010 nitrogen-vacancy centers in a diamond crystal coupled to a superconducting L C resonator. The energy of the signal, retrieved 100 ? s later by spin-echo techniques, reaches 0.3 % of the energy absorbed by the spins. This 0.3 % storage efficiency is quantitatively accounted for by simulations. This figure of merit is sufficient to envision first implementations of a quantum memory for superconducting qubits.

  11. Spin-one Heisenberg antiferromagnetic chain with exchange and single-ion anisotropies

    NASA Astrophysics Data System (ADS)

    Peters, D.; McCulloch, I. P.; Selke, W.

    2009-04-01

    Using density-matrix renormalization group calculations, ground-state properties of the spin-1 Heisenberg chain with exchange and single-ion anisotropies in an external field are studied. Our findings confirm and refine recent numerical and analytic results by Sengupta and Batista [Phys. Rev. Lett. 99, 217205 (2007)] on the same model. In particular, we present evidence for two types of biconical (or supersolid) and for two types of spin-flop (or superfluid) structures for chains of finite length. Basic features of the quantum phase diagram may be interpreted qualitatively in the framework of classical spin models.

  12. Direct observation of dynamics of single spinning dust grains in weakly magnetized complex plasma

    SciTech Connect

    Dzlieva, E. S.; Karasev, V. Yu.; Petrov, O. F.

    2012-01-15

    The rotational dynamics of single dust grains in a weak magnetic field is investigated on a kinetic level. Experiments reveal spin-up of spherical dust grains and alignment of their magnetic moments parallel to the magnetic induction vector. The angular velocity of spinning prolate grains varies as magnetic induction increases to 250 G. Spinning dust grains are found to flip over only when the magnetic field magnitude is changing. The results demonstrate that dusty plasma has paramagnetic properties. Qualitative interpretations are proposed to explain newly discovered phenomena.

  13. 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.

  14. The coherent optical spectroscopy and control of an electron spin in a self-assembled quantum dot for quantum computing

    NASA Astrophysics Data System (ADS)

    Kim, Erik D.

    Self-assembled quantum dots (QDs) containing a single electron are one of the leading candidate systems for the realization of a quantum computer. The spin states of charges confined in these dots have been shown to possess a number of qualities that are attractive for use as the quantum bits (qubits) in quantum computing implementations, particularly their long lifetimes and coherence times. In addition, these spin qubits may be controlled optically, offering the prospect of ultrafast qubit gate operations, a crucial necessity for the execution of quantum algorithms. Due to the weak interaction of self-assembled QDs with light, however, the coherent optical control and read-out of the spin states of charged self-assembled QDs has proven to be a considerable challenge. This thesis presents two sets of experiments demonstrating the coherent optical control and read-out of the quantum states of a self assembled InAs QD containing a single electron. The first utilizes mode-locked picosecond optical pulses to control the optical transitions in the dot and to detect QD level occupations. These capabilities are used to observe transient phenomena in a singly charged InAs QD such as the generation and decay of excited state population and spin precession. Further, Rabi oscillations between the electron and the lowest-lying excited state are observed, demonstrating the ability to coherently control the optical transitions of the QD, a prerequisite for spin control. These results are built upon in the second set of experiments, in which a combination of optical pulses, an externally applied DC magnetic field and a continuous-wave (CW) optical field are employed to initialize and completely control the states of a QD confined electron spin. Spin control by the use of pulse-driven two-photon Raman processes, spin precession about the external magnetic field and geometric phases generated by CW-driven cyclic evolutions in the dot is demonstrated. A number of spin qubit gate operations are shown for these spin control mechanisms, forming a foundational set of single qubit gates required for the implementation of quantum computing with singly charged self-assembled QDs.

  15. Oscillatory Spin-Filtering due to Gate Control of Spin-Dependent Interface Conductance

    NASA Astrophysics Data System (ADS)

    Grundler, Dirk

    2001-02-01

    Using the Landauer-Bttiker formalism, we study ballistic transport properties of an interface between a ferromagnetic metal and a mesoscopic two-dimensional electron system in a III-V semiconductor. We show that in a Sharvin point contact spin-filtering occurs due to band structure mismatch. Theory predicts a pronounced effect for Fe on InAs which can be controlled via a gate electrode.

  16. 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

  17. Spin-Tunnel Investigation of the Spinning Characteristics of Typical Single-Engine General Aviation Airplane Designs. 1. Low-Wing Model A: Effects of Tail Configurations

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    The effects of tail design on spin and recovery were investigated in a spin tunnel. A 1/11-scale model of a research airplane which represents a typical low-wing, single engine, light general aviation airplane was used. A tail design criterion for satisfactory spin recovery for light airplanes was evaluated. The effects of other geometric design features on the spin and recovery characteristics were also determined. Results indicate that the existing tail design criterion for light airplanes, which uses the tail damping power factor as a parameter, cannot be used to predict spin-recovery characteristics.

  18. 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. PMID:26955799

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

    SciTech Connect

    Schler, 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.

  20. Magnetic attitude control system for dual-spin satellites

    NASA Technical Reports Server (NTRS)

    Alfriend, K. T.

    1975-01-01

    A closed-loop control law is developed for a dual-spin satellite control system which utilizes the interaction of the geomagnetic field with the satellite dipole parallel to the spin axis. The control law consists of the linear combination of the pitch axis component of the rate of change of the geomagnetic field and the product of the roll angle and roll axis component of the geomagnetic field. Application of the method of multiple time scales yields approximate solutions for the feedback gains in terms of the system parameters. Approximate solutions are also obtained for the response of the system to disturbance torques. A comparison of the approximate solutions and numerical solutions obtained by numerical integration of the exact equations of motion is then given.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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 Yb3 + 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 Yb3 + 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.

  2. Nanoscale microwave imaging with a single electron spin in diamond

    NASA Astrophysics Data System (ADS)

    Appel, Patrick; Ganzhorn, Marc; Neu, Elke; Maletinsky, Patrick

    2015-11-01

    We report on imaging of microwave (MW) magnetic fields using a magnetometer based on the electron spin of a nitrogen vacancy (NV) center in diamond. We quantitatively image the magnetic field generated by high frequency (GHz) MW current with nanoscale resolution using a scanning probe technique. Together with a shot noise limited MW magnetic field sensitivity of 680 nT Hz?1/2 our room temperature experiments establish the NV center as a versatile and high performance tool for MW imaging, which furthermore offers polarization selectivity and broadband capabilities. As a first application of this scanning MW detector, we image the MW stray field around a stripline structure and thereby locally determine the MW current density with a MW current sensitivity of a few nA Hz?1/2.

  3. A coherent triggered search for single-spin compact binary coalescences in gravitational wave data

    NASA Astrophysics Data System (ADS)

    Harry, I. W.; Fairhurst, S.

    2011-07-01

    In this paper, we present a method for conducting a coherent search for single-spin compact binary coalescences in gravitational wave data and compare this search to the existing coincidence method for single-spin searches. We propose a method to characterize the regions of the parameter space where the single-spin search, both coincident and coherent, will increase detection efficiency over the existing non-precessing search. We also show example results of the coherent search on a stretch of data from Laser Interferometer Gravitational-wave Observatory's fourth science run, but note that a set of signal-based vetoes will be needed before this search can be run to try to make detections.

  4. Non-equilibrium spin polarization via real-time control of spin fluctuations in a semiconductor nanowire

    NASA Astrophysics Data System (ADS)

    Peddibhotla, Phani; Xue, Fei; Hauge, Ikaros; Bakkers, Erik; Poggio, Martino

    2013-03-01

    The implementation of electron spins as solid-state qubits suffers from decoherence due to its hyperfine interaction with the surrounding mesoscopic nuclear spin environment. Several methods such as complete polarization or narrowing of the nuclear spin ensemble have been proposed in order to address this issue. These proposals have been realized in quantum dots using an optical or electrical readout of the nuclear magnetic field. Here we demonstrate a similar control over a nanoscale ensemble of spins using the mechanical readout of magnetic resonance force microscopy (MRFM). We employ the exceptional sensitivity of MRFM to perform real-time measurement and control of an ensemble containing 105 nuclear spins in a semiconductor nanowire. We create hyperpolarized and narrowed nuclear spin states by harnessing the statistical fluctuations of the ensemble. Furthermore, we capture large nuclear polarization fluctuations, store them for many seconds, and read the polarization out.

  5. 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.

  6. 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.

  7. Optimal control of two coupled spinning particles in the EulerLagrange picture

    NASA Astrophysics Data System (ADS)

    Delgado-Tllez, M.; Ibort, A.; Rodrguez de la Pea, T.; Salmoni, R.

    2016-01-01

    A family of optimal control problems for a single and two coupled spinning particles in the EulerLagrange 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 Pontryagins 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.

  8. Control phase shift of spin-wave by spin-polarized current and its application in logic gates

    NASA Astrophysics Data System (ADS)

    Chen, Xiangxu; Wang, Qi; Liao, Yulong; Tang, Xiaoli; Zhang, Huaiwu; Zhong, Zhiyong

    2015-11-01

    We proposed a new ways to control the phase shift of propagating spin waves by applying a local spin-polarized current on ferromagnetic stripe. Micromagnetic simulation showed that a phase shift of about ? can be obtained by designing appropriate width and number of pinned magnetic layers. The ways can be adopted in a Mach-Zehnder-type interferometer structure to fulfill logic NOT gates based on spin waves.

  9. 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.

  10. 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.

  11. Electrical control of the spin-flip rate of an exciton in a semiconductor

    NASA Astrophysics Data System (ADS)

    Warburton, Richard

    2005-03-01

    At the heart of the Kondo effect is a tunneling process in which a localised electron is exchanged with an electron in a Fermi sea. This process can flip the spin of the localised electron. We present here a novel application of this concept to an exciton, an electron-hole complex, in a quantum dot. By determining the temporal emission characteristics of a single self-assembled quantum dot, we show that the exciton spin can be reversed through an electron exchange with a Fermi sea in a neighboring n-doped layer. A very significant point is that the exciton spin flip completely changes the radiative properties of the exciton, either from dark to bright or from bright to dark. We can control the rate of the spin flip to be either much larger or much smaller than the radiative recombination rate of the bright exction simply with the voltage applied to the gate of our device. Calculations based on the Anderson Hamiltonian give excellent agreement with the experimental results. Our work has important consequences in two areas. First, the effect corresponds to the high temperature Kondo regime, motivating the possibility of observing a Kondo exciton in a semiconductor nanostructure for the first time. Secondly, the effect offers a way of manipulating the dark exciton and therefore a means of exploiting its long lifetime and long spin coherence time in quantum information processing.

  12. 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.

  13. On the control of spin flop in synthetic antiferromagnetic films

    NASA Astrophysics Data System (ADS)

    Negulescu, B.; Lacour, D.; Hehn, M.; Gerken, A.; Paul, J.; Duret, C.

    2011-05-01

    The paper presents a systematic study of anneal induced anisotropies in a CoFe/Ru/CoFe synthetic antiferromagnet (SAF) exchange coupled with an IrMn film. When the annealing is done with the SAF in a spin flop state, the magnetic layers can be pinned perpendicular to the annealing field direction. The main parameters controlling this process are identified and analyzed: the value and the direction of the annealing field along with the Ruderman-Kittel-Kasuya-Yosida coupling energy between the two ferromagnetic layers. The induced anisotropy is predicted within a theoretical model taking into account the thermal variation of the coupling constants. Finally, the spin flop annealing is used to orthogonally pin the reference and the detection electrodes in an IrMn/CoFe/Ru/CoFe/Cu/CoFe/IrMn spin valve structure. The magnetoresistance variation in this structure is analyzed as a function of the pinning direction of the SAF acquired during the annealing in the spin flop state. A very good agreement is observed between the experimental and theoretically predicted responses.

  14. 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.

  15. 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.

  16. Influences of DMI on spin-polarized current through a single-molecule magnet

    NASA Astrophysics Data System (ADS)

    Luo, Bo; Liu, Juan; Yao, Kai-Lun

    2013-11-01

    We theoretically investigate the influences of the Dzyaloshinskii-Moriya interaction (DMI) on the spin-polarized transport through a single-molecular magnets, which is weakly coupled to ferromagnetic lead-L(pL) and nonmagnetic lead-R. The spin current is obtained by means of the rate-equation approach in the sequential-tunneling region. Due to the coherent superposition of the molecular state |1 induced by the DMI, we can observe the continuous pure spin current and negative differential conductance (NDC) under the full polarization pL=1 condition and polarization reversal of spin-current in the case of 0

  17. Electron spin resonance of irradiated single crystals of L-phenylalanine-HCl.

    PubMed

    Fasanella, E L; Gordy, W

    1969-09-01

    Single crystals of L-phenylalanine-HCl have been observed with electron spin resonance after irradiation with a cobalt 60 gamma-ray source. The predominant signals observed are from long-lived benzyl radicals. The results indicate that one form of radiation damage to proteins containing this amino acid is breakage of the carbon-carbon bond to release the benzyl radical from the polypeptide chain. Hyperfine structure due to proton couplings of the two methylene hydrogens and of the hydrogens on the ring of the benzyl radical is observed and analyzed to give the electron spin density on the various carbons. The spin density on the methylene carbon is found to be 0.71; that on carbon C((2)), C((4)), or C((6)) is 0.17. The sum of the spin densities on C((1)), C((3)), and C((5)) is -0.22. PMID:4312748

  18. 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.

  19. Spin-Relaxation Dynamics of E' Centers at High Density in SiO2 Thin Films for Single-Spin Tunneling Force Microscopy

    NASA Astrophysics Data System (ADS)

    Ambal, K.; Payne, A.; Waters, D. P.; Williams, C. C.; Boehme, C.

    2015-08-01

    The suitability of the spin dynamics of paramagnetic silicon dangling bonds (E' centers) in high-E'-density amorphous silicon dioxide (SiO2 ) as probe spins for single-spin tunneling force microscopy (SSTFM) is studied. SSTFM is a spin-selection-rule-based scanning-probe single-spin readout concept. Following the synthesis of SiO2 thin films on (111)-oriented crystalline-silicon substrates with room-temperature stable densities of [E'] >5 ×1018 cm-3 throughout the 60-nm thin film, pulsed electron paramagnetic resonance spectroscopy is conducted on the E' centers at temperatures between T =5 K and T =70 K . The measurements reveal that the spin coherence (the transverse spin-relaxation time T2) of these centers is significantly shortened compared to low-E'-density SiO2 films and within error margins not dependent on temperature. In contrast, the spin-flip times (the longitudinal relaxation times T1) are dependent on the temperature but with much weaker dependence than low-density SiO2 , with the greatest deviations from low-density SiO2 seen for T =5 K . These results, discussed in the context of the spin-relaxation dynamics of dangling-bond states of other silicon-based disordered solids, indicate the suitability of E' centers in high-density SiO2 as probe spins for SSTFM.

  20. Self-spin-controlled rotation of spatial states of a Dirac electron in a cylindrical potential via spin orbit interaction

    NASA Astrophysics Data System (ADS)

    Leary, C. C.; Reeb, D.; Raymer, M. G.

    2008-10-01

    Solution of the Dirac equation predicts that when an electron with nonzero orbital angular momentum (OAM) propagates in a cylindrically symmetric potential, its spin and orbital degrees of freedom interact, causing the electron's phase velocity to depend on whether its spin angular momentum (SAM) and OAM vectors are oriented parallel or anti-parallel with respect to each other. This spin orbit splitting of the electronic dispersion curves can result in a rotation of the electron's spatial state in a manner controlled by the electron's own spin z-component value. These effects persist at non-relativistic velocities. To clarify the physical origin of this effect, we compare solutions of the Dirac equation to perturbative predictions of the Schrdinger Pauli equation with a spin orbit term, using the standard Foldy Wouthuysen Hamiltonian. This clearly shows that the origin of the effect is the familiar relativistic spin orbit interaction.

  1. Controllable coupling between a charge qubit and a spin ensemble

    NASA Astrophysics Data System (ADS)

    He, Xiao-Ling; Yang, Chui-Ping; Luo, Jun-Yan; Shen, Yu; Pan, Wei-Qing; Li, Sheng

    2014-06-01

    We propose a scheme to control the coupling between the charge qubit and the nitrogen-vacancy center ensemble (NVCE). The coupling is mediated by a large Josephson junction (JJ) and a flux qubit. The large JJ can be treated classically and behaves like an effective inductance to switch the coupling between the charge and flux qubits. The flux qubit serves as a bridge to couple the NVCE and the charge qubit, and quantum state transfer can be implemented, with the NVCE acting as a memory unit. The hybrid circuit can reinforce various advantages: controllability of the charge qubit and robust spin coherence of the NVCE.

  2. 1020 MHz single-channel proton fast magic angle spinning solid-state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    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 (1020 MHz) NMR spectrometer comprised of HTS/LTS magnet. High spectral resolution is well demonstrated.

  3. 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. PMID:26524647

  4. 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

  5. Shot noise as a probe of spin-polarized transport through single atoms.

    PubMed

    Burtzlaff, Andreas; Weismann, Alexander; Brandbyge, Mads; Berndt, Richard

    2015-01-01

    Single atoms on Au(111) surfaces have been contacted with the Au tip of a low temperature scanning tunneling microscope. The shot noise of the current through these contacts has been measured up to frequencies of 120 kHz and Fano factors have been determined to characterize the transport channels. The noise at Fe and Co atoms, the latter displaying a Kondo effect, indicates spin-polarized transport through a single channel. Transport calculations reproduce this observation. PMID:25615489

  6. Electron spin decoherence by interacting nuclear spins in quantum dot II: Coherent control

    NASA Astrophysics Data System (ADS)

    Liu, Ren-Bao; Yao, Wang; Sham, Lu J.

    2006-03-01

    Due to the hyperfine interaction, the nuclear spins in a quantum dot, driven by nuclear spin pair-wise flip-flops, evolve in different pathways in the Hilbert space for different electron spin states, resulting in the electron-nuclei entanglement and hence the electron spin decoherence. When the electron spin is flipped by a pulse, the nuclear spin states for different electron spin states swap their pathways, and could intersect in the Hilbert space, which disentangles the electron and the nuclei and hence restores the electron spin coherence. The coherence restoration by disentanglement and the conventional spin echo in ensemble dynamics are fundamentally different and generally occur at different time. Pulse sequences can be applied to force the disentanglement to coincide with the spin echo, making the coherence recovery observable in ensemble dynamics. This work was supported by NSF DMR-0403465, NSA/ARO, and DARPA/AFOSR.

  7. Electric Field Control of Spin Lifetimes in Nb -SrTiO3 by Spin-Orbit Fields

    NASA Astrophysics Data System (ADS)

    Kamerbeek, A. M.; Hgl, P.; Fabian, J.; Banerjee, T.

    2015-09-01

    We show electric field control of the spin accumulation at the interface of the oxide semiconductor Nb -SrTiO3 with Co /AlOx spin injection contacts at room temperature. The in-plane spin lifetime ??, as well as the ratio of the out-of-plane to in-plane spin lifetime ??/??, is manipulated by the built-in electric field at the semiconductor surface, without any additional gate contact. The origin of this manipulation is attributed to Rashba spin orbit fields (SOFs) at the Nb -SrTiO3 surface and shown to be consistent with theoretical model calculations based on SOF spin flip scattering. Additionally, the junction can be set in a high or low resistance state, leading to a nonvolatile control of ??/??, consistent with the manipulation of the Rashba SOF strength. Such room temperature electric field control over the spin state is essential for developing energy-efficient spintronic devices and shows promise for complex oxide based (spin) electronics.

  8. Electric Field Control of Spin Lifetimes in Nb-SrTiO_{3} by Spin-Orbit Fields.

    PubMed

    Kamerbeek, A M; Hgl, P; Fabian, J; Banerjee, T

    2015-09-25

    We show electric field control of the spin accumulation at the interface of the oxide semiconductor Nb-SrTiO_{3} with Co/AlO_{x} spin injection contacts at room temperature. The in-plane spin lifetime ?_{?}, as well as the ratio of the out-of-plane to in-plane spin lifetime ?_{?}/?_{?}, is manipulated by the built-in electric field at the semiconductor surface, without any additional gate contact. The origin of this manipulation is attributed to Rashba spin orbit fields (SOFs) at the Nb-SrTiO_{3} surface and shown to be consistent with theoretical model calculations based on SOF spin flip scattering. Additionally, the junction can be set in a high or low resistance state, leading to a nonvolatile control of ?_{?}/?_{?}, consistent with the manipulation of the Rashba SOF strength. Such room temperature electric field control over the spin state is essential for developing energy-efficient spintronic devices and shows promise for complex oxide based (spin) electronics. PMID:26451572

  9. 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.

  10. Stability of spin-electric coupling in triangular single-molecule magnets under external contacts

    NASA Astrophysics Data System (ADS)

    Islam, Fhokrul; Nossa, Javier; Canali, Carlo; Pederson, Mark

    2015-03-01

    Triangular single molecule magnets (SMMs) with antiferromagnetic exchange coupling exhibit Kramer degenerate chiral spin-doublets ground states, which can be efficiently coupled by an electric field, even in the absence of spin-orbit interaction. Recent first-principles calculations show that unsupported V3 SMM has giant spin-electric coupling corresponding to dipole moment of about one tenth of the water-molecule dipole moment. The corresponding Rabi time for electric switching between two chiral states can be on the order of one nano-second for reasonable electric fields, which makes these molecules very attractive candidates for storing and manipulating pairs of coupled spin-chiral qbits. However, for device applications of the spin-electric coupling, these frustrated SMMs need to be supported on a surface or between metallic leads. Preserving this effect in an external environment is a challenging problem requiring appropriate functionalization. In this talk we will discuss the stability of the spin-electric coupling in V3 SMM when coupled to gold leads or deposited on a graphene surface.

  11. Enhancement of the electron spin resonance of single-walled carbon nanotubes by oxygen removal.

    PubMed

    Rice, William D; Weber, Ralph T; Leonard, Ashley D; Tour, James M; Nikolaev, Pavel; Arepalli, Sivaram; Berka, Vladimir; Tsai, Ah-Lim; Kono, Junichiro

    2012-03-27

    We have observed a nearly 4-fold increase in the electron spin resonance (ESR) signal from an ensemble of single-walled carbon nanotubes (SWCNTs) due to oxygen desorption. By performing temperature-dependent ESR spectroscopy both before and after thermal annealing, we found that the ESR in SWCNTs can be reversibly altered via the molecular oxygen content in the samples. Independent of the presence of adsorbed oxygen, a Curie law (spin susceptibility ? 1/T) is seen from ~4 to 300 K, indicating that the probed spins are finite-level species. For both the pre-annealed and post-annealed sample conditions, the ESR line width decreased as the temperature was increased, a phenomenon we identify as motional narrowing. From the temperature dependence of the line width, we extracted an estimate of the intertube hopping energy; for both sample conditions, we found this hopping energy to be ~1.2 meV. Since the spin hopping energy changes only slightly when oxygen is desorbed, we conclude that only the spin susceptibility, not spin transport, is affected by the presence of physisorbed molecular oxygen in SWCNT ensembles. Surprisingly, no line width change is observed when the amount of oxygen in the SWCNT sample is altered, contrary to other carbonaceous systems and certain 1D conducting polymers. We hypothesize that physisorbed molecular oxygen acts as an acceptor (p-type), compensating the donor-like (n-type) defects that are responsible for the ESR signal in bulk SWCNTs. PMID:22324937

  12. 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.

  13. 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.

  14. Tunable topological insulators with a single spin-polarized surface Dirac cone

    NASA Astrophysics Data System (ADS)

    Hsieh, David

    2010-03-01

    The topological insulator is a fundamentally new time-reversal-invariant topologically ordered phase of matter, which exhibits exotic quantum-Hall-like behavior even in the absence of an applied magnetic field. These materials are characterized by a spin-orbit coupling induced bulk energy gap and an odd number of spin-polarized Dirac cones localized on their surfaces. In this talk, I will review the first experimental realization of the topological insulator in Bi1-xSbx [1,2], and then report our recent experimental discovery and findings of a new generation of topological insulators with order-of-magnitude larger bulk band gaps and a single spin-helical surface Dirac cone [3,4]. I will also discuss a novel `effective gating' technique that can be used to optimize the insulating properties of the bulk, and to tune the Dirac carrier density on the surfaces of these new topological insulators [5]. These experiments pave the way for future transport based studies of topological insulator devices, and offer the potential for a graphene-like revolution to take place for topological insulators. [1] ``A topological Dirac insulator in a quantum spin Hall phase'', D. Hsieh et al., Nature 452, 970 (2008). [2] ``Observation of unconventional quantum spin textures in topological insulators'', D. Hsieh et al., Science 323, 919 (2009). [3] ``Observation of a large-gap topological-insulator class with a single Dirac cone on the surface'', Y. Xia et al., Nature Phys. 5, 398 (2009). [4] ``Observation of time-reversal-protected single-Dirac-cone topological-insulator states in Bi2Te3 and Sb2Te3'', D. Hsieh et al., Phys. Rev. Lett., 103, 146401 (2009). [5] ``A tunable topological insulator in the spin helical Dirac transport regime'', D. Hsieh et al., Nature 460, 1101 (2009).

  15. Hyperon production mechanisms and single-spin asymmetry in high energy hadron-hadron collisions

    SciTech Connect

    Boros, C.; Zuo-tang, L.

    1996-03-01

    It is shown that the existence of left-right asymmetry in single-spin inclusive {Lambda} production, together with the characteristic features of the data, should be considered as another clear signature for the existence of orbiting valence quarks in polarized nucleons. Predictions for other hyperons are made. It is pointed out that measurements of such asymmetries are very helpful not only for probing the spin structure of the nucleons but also for studying the production mechanisms of the hyperons. {copyright} {ital 1996 The American Physical Society.}

  16. Non-equilibrium transport and spin dynamics in single-molecule magnets

    NASA Astrophysics Data System (ADS)

    Moldoveanu, V.; Dinu, I. V.; Tanatar, B.

    2015-11-01

    The time-dependent transport through single-molecule magnets (SMM) coupled to magnetic or non-magnetic electrodes is studied in the framework of the generalized Master equation (GME) method. We calculate the transient currents which develop when the molecule is smoothly coupled to the source and drain electrodes. The signature of the electrically induced magnetic switching on these transient currents is investigated. Our simulations show that the magnetic switching of the molecular spin can be read indirectly from the transient currents if one lead is magnetic and it is much faster if the leads have opposite spin polarizations. We identify effects of the transverse anisotropy on the dynamics of molecular states.

  17. Spin Measurements of an Electron Bound to a Single Phosphorous Donor in Silicon

    NASA Astrophysics Data System (ADS)

    Luhman, D. R.; Nguyen, K.; Tracy, L. A.; Carr, S. M.; Borchardt, J.; Bishop, N. C.; Ten Eyck, G. A.; Pluym, T.; Wendt, J.; Carroll, M. S.; Lilly, M. P.

    2014-03-01

    The spin of an electron bound to a single donor implanted in silicon is potentially useful for quantum information processing. We report on our efforts to measure and manipulate the spin of an electron bound to a single P donor in silicon. A low number of P donors are implanted using a self-aligned process into a silicon substrate in close proximity to a single-electron-transistor (SET) defined by lithographically patterned polysilicon gates. The SET is used to sense the occupancy of the electron on the donor and for spin read-out. An adjacent transmission line allows the application of microwave pulses to rotate the spin of the electron. We will present data from various experiments designed to exploit these capabilities. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE Office of Basic Energy Sciences user facility. The work was supported by Sandia National Laboratories Directed Research and Development Program. 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.

  18. 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.

  19. Single-shot readout and relaxation measurements in exchange coupled 31 P electron spins in silicon

    NASA Astrophysics Data System (ADS)

    Dehollain, Juan Pablo; Muhonen, Juha; Tan, Kuan; Saraiva, Andre; Jamieson, David; Dzurak, Andrew; Morello, Andrea

    2015-03-01

    We present the experimental observation of a large exchange coupling J ~ 300 ?eV between two 31 P electron spin qubits in silicon. The singlet and triplet states of the coupled spins are monitored in real time by a single-electron transistor, which detects ionization from tunnel-rate-dependent processes in the coupled spin system, yielding single-shot readout fidelities above 95%. The triplet to singlet relaxation time T1 ~ 4 ms at zero magnetic field agrees with the theoretical prediction for the observed J-coupling energy in 31 P dimers in silicon. The three order of magnitude increase in relaxation rate compared to single donors, is caused by a hyperfine interaction mediated mixing of the singlet and triplet states. Additionally, the time evolution of the two-electron state populations reveals an inversion in the energetic hierarchy of the valley-orbit excited states, which had been theoretically predicted for donor pairs with < 6 nm separation. These results pave the way to the realization of two-qubit quantum logic gates with spins in silicon and highlight the necessity to adopt gating schemes compatible with weak J-coupling strengths.

  20. UNIQUE DESCRIPTION FOR SINGLE TRANSVERSE SPIN ASYMMETRIES IN DIS AND HADRONIC COLLISIONS.

    SciTech Connect

    YUAN, F.

    2006-12-18

    We derive a unique formula for the single-transverse-spin asymmetry in semi-inclusive hadron production in deep inelastic scattering, valid for all transverse momentum region. Based on this, we further study the integrated asymmetry weighted with transverse-momentum. They can be evaluated in terms of the twist-three quark-gluon correlation functions, which are responsible for the single spin asymmetry in single inclusive hadron production in hadronic collisions. By using the fitted twist-three functions from the hadronic collision data, we find a consistent description for SSAs in deep inelastic scattering. This demonstrates that we have a unique picture for SSAs in these two processes, and shall provide important guidelines for future studies.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. 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.

  4. 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.

  5. FEM Optimization of Spin Forming Using a Fuzzy Control Algorithm

    NASA Astrophysics Data System (ADS)

    Yoshihara, S.; Ray, P.; MacDonald, B. J.; Koyama, H.; Kawahara, M.

    2004-06-01

    Finite element (FE) simulation of the manufacturing of a conical nosing such as a pressure vessel from circular tubes, using the spin forming method, was performed on the commercially available software package, ANSYS/LS-DYNA3D. The finite element method (FEM) provides a powerful tool for evaluating the potential to form the pressure vessel with proposed modifications to the process. The use of fuzzy logic inference as a control system to achieve the designed shape of the pressure vessel was investigated using the FEM. The path of the roller as a process parameter was decided by the fuzzy inference control algorithm from information of the result of deformation of each element respectively. The fuzzy control algorithm investigated was validated from the results of the production process time and the deformed shape using FE simulation.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. 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

    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.

  8. 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.

  9. Cotunneling signatures of spin-electric coupling in frustrated triangular single-molecule magnets

    NASA Astrophysics Data System (ADS)

    Nossa, Javier; Canali, Carlo

    2013-03-01

    The ground state (GS) of frustrated (antiferromagnetic) triangular single-molecule magnets is characterized by two total-spin S = 1 /2 doublets with opposite chirality. According to a group theory analysis [M. Trif et al., Phys. Rev. Lett. 101, 217201 (2008)] an external electric field can efficiently couple these two chiral spin states, even when the spin-orbit interaction (SOI) is absent. The strength of this coupling, d, is determined by an off-diagonal matrix element of the dipole operator, which can be calculated by ab-initio methods [M. F. Islam et al., Phys. Rev. B 82, 155446 (2010)]. In this work we propose that Coulomb-blockade transport experiments in the cotunneling regime can provide a direct way to determine the spin-electric coupling strength. Indeed, an electric field generates a d-dependent splitting of the GS manifold, which can be detected in the inelastic cotunneling conductance. Our theoretical analysis is supported by master-equation calculations of quantum transport in the cotunneling regime. We employ a Hubbard-model approach to elucidate the relationship between the Hubbard parameters t and U, and the spin-electric coupling constant d . This allows us to predict the regime in which the coupling constant d can be extracted from experiment.

  10. Spontaneous formation and spin of particle pairs in a single-layer complex plasma crystal

    NASA Astrophysics Data System (ADS)

    Nosenko, V.; Zhdanov, S. K.; Thomas, H. M.; Carmona-Reyes, J.; Hyde, T. W.

    2015-11-01

    In an experiment with a single-layer plasma crystal, spontaneous pairing of particles was observed upon a sudden reduction of the discharge power. The pairs were oriented vertically with the upper particle above the crystal layer and the lower particle beneath it, the pair size was about 0.2 mm. The pairs were spinning around their vertical axis with the upper particle leading and the lower one following it; the rotation speed was 1013 Hz. Spinning particle pairs disturbed the plasma crystal through interaction with their neighbors. Upon further reduction of the discharge power, the spinning pairs proliferated in the plasma crystal and eventually it melted. The experiment was performed with micron-size polymer particles suspended in the radio-frequency (rf) argon plasma at a pressure of 157 mtorr. We propose a theoretical model of a spinning particle pair based on the plasma wake effect. Spinning particle pairs can be used as a diagnostic tool for plasma wakes or as a generic model of a 2D system of vortices.

  11. 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.

  12. 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.

  13. Magnetic anisotropy and high-spin effects in single-molecule transistors

    NASA Astrophysics Data System (ADS)

    Zyazin, Alexander; van den Berg, Johan; Osorio, Edgar; Konstantinidis, Nikos; Leijnse, Martin; May, Falk; Hofstetter, Walter; Danieli, Chiara; Cornia, Andrea; Wegewijs, Maarten; van der Zant, Herre

    2011-03-01

    Fabrication of single-molecule transistors where electron transport occurs through an individual molecule has become possible due to the recent progress in molecular electronics. Three-terminal configuration allows charging molecules and performing transport spectroscopy in multiple redox states. Single-molecule magnets combining large spin with uniaxial anisotropy are of special interest as appealing candidates for high density memory applications and quantum information processing. We study single-molecule magnets Fe 4 . Three-terminal junctions are fabricated using electromigration of gold nanowires followed by a self-breaking. High-spin Kondo effect and inelastic cotunneling excitations show up in transport measurements. Several excitations feature the energy close to the energy of zero-field splitting (ZFS) of a ground spin multiplet in bulk. This splitting is caused by the anisotropy and is a hallmark of single-molecule magnets. We observe nonlinear Zeeman effect due to a misalignment of an anisotropy axis and a magnetic field direction. The ZFS energy is increased in oxidized and reduced states of the molecule indicating enhancement of the anisotropy in these states.

  14. 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 increased our understanding and raised the prospects of spin qubits in Si/SiGe quantum dots. This work has been done in collaboration with T.M. J. Jullien, P. Scarlino, V.V. Dobrovitski, D.R. Ward, D. E. Savage, M. G. Lagally, Mark Friesen, S. N. Coppersmith, M. A. Eriksson, and L. M. K. Vandersypen. This work was supported in part by the Army Research Office (ARO) (W911NF-12-0607), the Foundation for Fundamental Research on Matter (FOM) and the European Research Council (ERC). Development and maintenance of the growth facilities used for fabricating samples was supported by the Department of Energy (DOE) (DE-FG02-03ER46028). E.K. was supported by a fellowship from the Nakajima Foundation. This research utilized NSF-supported shared facilities at the University of Wisconsin-Madison.

  15. 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. PMID:25961508

  16. 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.

  17. Coherent Optical Control of Quantum Dots: Spin Qubits and Flying Qubits

    NASA Astrophysics Data System (ADS)

    Burgers, Alex

    2015-03-01

    Coherent control of solid-state qubits lies at the heart of most quantum information architectures. In quantum dots (QDs), optical fields are an attractive medium for qubit manipulation and readout. The entanglement between a QD spin qubit and an emitted photonic qubit allows for the transport of quantum information between distant quantum memories via decoherence resistant photon channels. I will present recent experimental work showing the entanglement between a single electron spin confined to an InAs QD and its spontaneously emitted photon. This entanglement is significant for the further development of quantum information technologies using QDs and forms the foundation of on-chip technologies using photonic crystal pathways. In addition, I will discuss on-going work on teleportation of information from a single photon generated in a spontaneous parametric down conversion (SPDC) process to a QD spin through intermediate interference between the SPDC photon and the dot's emitted photon. The ability to integrate two quantum information platforms is not only exciting in its own right, but this technique could allow for an entanglement swapping bridge between other matter-qubit (ions, NV centers, etc.) based quantum memories. This work is funded by NSF, ARO, AFOSR, ONR and DARPA.

  18. 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.

  19. Spin dynamics in the single molecule magnet Ni4 under microwave irradiation

    NASA Astrophysics Data System (ADS)

    de Loubens, Gregoire

    2009-03-01

    Quantum mechanical effects such as quantum tunneling of magnetization (QTM) and quantum phase interference have been intensively studied in single molecule magnets (SMMs). These materials have also been suggested as candidates for qubits and are promising for molecular spintronics. Understanding decoherence and energy relaxation mechanisms in SMMs is then both of fundamental interest and important for the use of SMMs in applications. Interestingly, the single-spin relaxation rate due to direct process of a SMM embedded in an elastic medium can be derived without any unknown coupling constant [1]. Moreover, nontrivial relaxation mechanisms are expected from collective effects in SMM single crystals, such as phonon superradiance or phonon bottleneck. In order to investigate the spin relaxation between the two lowest lying spin-states of the S=4 single molecule magnet Ni4, we have developed an integrated sensor that combines a microstrip resonator and micro-Hall effect magnetometer on a chip [2]. This sensor enables both real time studies of magnetization dynamics under pulse irradiation as well as simultaneous measurements of the absorbed power and magnetization changes under continuous microwave irradiation. The latter technique permits the study of small deviations from equilibrium under steady state conditions, i.e. small amplitude cw microwave irradiation. This has been used to determine the energy relaxation rate of a Ni4 single crystal as a function of temperature at two frequencies, 10 and 27.8 GHz. A strong temperature dependence is observed below 1.5 K, which is not consistent with a direct spin-phonon relaxation process. The data instead suggest that the spin relaxation is dominated by a phonon bottleneck at low temperatures and occurs by an Orbach process involving excited spin-levels at higher temperatures [3]. Experimental results will be compared with detailed calculations of the relaxation rate using the density matrix equation with the relaxation terms in the universal form.1. E. M. Chudnovsky, D. A. Garanin and R. Schilling, Phys. Rev. B 72, 094426 (2005)2. G. de Loubens et al., J. Appl. Phys. 101, 09E104 (2007)3. G. de Loubens, D. A. Garanin, C. C. Beedle, D. N. Hendrickson and A. D. Kent, Europhys. Lett. 83, 37006 (2008)

  20. Coupled dynamics of magnetic spin and the Stokes parameters. Control of magnetization by polarized light

    NASA Astrophysics Data System (ADS)

    Kuratsuji, Hiroshi; Tsudagawa, Masaru

    2016-01-01

    A simple theoretical model is presented for the motion of a magnetic spin induced by polarized light. The model is analyzed by considering a coupled equation for two kinds of spin; the magnetic spin and optical spin (the Stokes parameters). The coupling between two spins is called Faraday coupling. The motion of magnetic spin shows inversion as a result of the structural change, which can be controlled by the ellipticity of the polarized light (the third component of the Stokes parameters). The motion of the Stokes parameters is also described as a reaction from the magnetic spin, by which the motion of magnetic spin could be monitored by ellipsometory. The present model may provide a basis for optical control of a magnetic micro-particle.

  1. 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.

  2. Production mechanisms and single-spin asymmetry for kaons in high energy hadron-hadron collisions

    SciTech Connect

    Boros, C.; Zuo-tang, L.; Ta-chung, M.

    1996-10-01

    The direct consequences on kaon production of the picture proposed in a recent Letter and subsequent publications are discussed. Further evidence supporting the proposed picture is obtained. A comparison with the data for the inclusive cross sections in unpolarized reactions is made. The quantitative results for the left-right asymmetry in single-spin processes are presented. {copyright} {ital 1996 The American Physical Society.}

  3. Transient dynamics in magnetic force microscopy for a single-spin measurement

    SciTech Connect

    Berman, G.P.; Borgonovi, F.; Lopez, G.V.; Tsifrinovich, V.I.

    2003-07-01

    We analyze a single-spin measurement using a transient process in magnetic force microscopy which could increase the maximum operating temperature by a factor of Q (the quality factor of the cantilever) in comparison with the static Stern-Gerlach effect. We obtain an exact solution of the master equation, which confirms this result. We also discuss the conditions required to create a macroscopic quantum superposition in the cantilever.

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

    DOE PAGESBeta

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  6. 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

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

    PubMed

    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 (13)C 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

  8. Hadron structure and left-right asymmetry in inclusive production in single-spin hadron-hadron collisions

    SciTech Connect

    Boros, C.; Liang Zuo-tang; Meng Ta-chung

    1995-05-01

    Theoretical arguments and experimental facts are presented which show the following. Left-right asymmetries are expected to exist in a number of single-spin inclusive production processes. Measuring such asymmetries by using different types of projectile-target combinations, one can obtain useful information on the spin structure of hadrons in general, and determine the spin-dependent quark distribution functions in particular. Quantitative predictions for these asymmetries in various reactions are presented.

  9. 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.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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-) 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- major axis in a straightforward manner.

  12. Digital atom interferometer with single particle control on a discretized space-time geometry.

    PubMed

    Steffen, Andreas; Alberti, Andrea; Alt, Wolfgang; Belmechri, Noomen; Hild, Sebastian; Karski, Michał; Widera, Artur; Meschede, Dieter

    2012-06-19

    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 x 10(-4) in units of gravitational acceleration g. PMID:22665771

  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. Spin transport enhancement by controlling the Ag growth in lateral spin valves

    NASA Astrophysics Data System (ADS)

    Isasa, Miren; Villamor, Estitxu; Fallarino, Lorenzo; Idigoras, Olatz; Suszka, Anna K.; Tollan, Christopher; Berger, Andreas; Hueso, Luis E.; Casanova, Flix

    2015-06-01

    The role of the growth conditions onto the spin transport properties of silver (Ag) have been studied by using lateral spin valve structures. By changing the deposition conditions of Ag from polycrystalline to epitaxial growth, we have observed a considerable enhancement of the spin diffusion length, from {?\\text{Ag}}=449+/- 30 to 823+/- 59 ?nm. This enhancement in the spin diffusion length is closely related to the grain size of the Ag channel, which is 19??????6?nm for polycrystalline Ag and 41??????4?nm for epitaxial Ag. This study shows that diminishing the grain boundary contribution to the spin relaxation mechanism is an effective way to improve the spin diffusion length in metallic nanostructures.

  15. TOPICAL REVIEW A review of the coherent optical control of the exciton and spin states of semiconductor quantum dots

    NASA Astrophysics Data System (ADS)

    Ramsay, A. J.

    2010-10-01

    The spin of a carrier trapped in a self-assembled quantum dot has the potential to be a robust optically active qubit that is compatible with existing III-V semiconductor device technology. A key requirement for building a quantum processor is the ability to dynamically prepare, control and detect single quantum states. Here, experimental progress in the coherent optical control of single semiconductor quantum dots over the past decade is reviewed, alongside an introductory discussion of the basic principles of coherent control.

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

    NASA Astrophysics Data System (ADS)

    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??s 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??s, 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.

  17. 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??s 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??s, 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

  18. Techniques for Noise Suppression and Robust Control in Spin-Based Quantum Information Processors

    NASA Astrophysics Data System (ADS)

    Borneman, Troy William

    Processing information quantum mechanically allows the relatively efficient solution of many important problems thought to be intractable on a classical computer. A primary challenge in experimentally implementing a quantum information processor is the control and suppression of environmental noise that decoheres the quantum system and causes it to behave classically. Environmental errors may be dynamically suppressed by applying coherent control pulses to the qubits that decouple the environment. However, the pulses themselves are subject to implementation errors, which hinders the ability to robustly store a complete quantum state. This thesis details results on the use of optimal control theory, noise twirling, and logical qubit encodings to design high-fidelity control pulses and decoupling sequences that are robust to implementation errors. Results are also presented that demonstrate how high-fidelity inductive control of a quantum system may be obtained with limited resonator bandwidth, with a discussion of applications to actuator-based quantum information processors. In a multinode design for such a processor, which allows efficient removal of entropy, a new protocol is suggested that permits robust parallel information transfer between nodes. The results detailed in this thesis apply broadly to most implementations of quantum information processing and specifically enable a new design for a spin-based multinode quantum information processor based on single-crystal molecular monolayer electron-nuclear spin systems integrated with superconducting electronics. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs@mit.edu)

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

    NASA Astrophysics Data System (ADS)

    Choudhary, Shashank; Tejesh, Chiruvolu Mohan; Regalla, Srinivasa Prakash; Suresh, Kurra

    2013-12-01

    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.

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  3. Controlling spinorbit interaction in a ferromagnetic Fe/Au double layer

    SciTech Connect

    Samarin, Sergey N.; Kostylev, Mikhail; Williams, James F.; Artamonov, Oleg M.; Baraban, Alexander P.; Guagliardo, Paul

    2015-01-26

    Using spin-polarized single- and two-electron spectroscopy, we probe exchange and spinorbit interaction in a double layer of Fe and Au on W(110) and measure the spin asymmetry of the Bloch spectral density function of the sample. In a 5?ML iron film, the spin-orbit contribution to the measured asymmetry of the (e,2e) spectra was not detectable, whereas a deposition of about 1?ML of gold introduced a substantial spin-orbit component in the measured asymmetry. At the same time, this double layer still exhibits ferromagnetic properties: (i) the spectral density function asymmetry demonstrate imbalance of spin-up and spin-down electron densities in the valence band and (ii) the Stoner excitation asymmetry has almost the same value as in a pure Fe film.

  4. 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.

  5. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Spin Relaxation of Electrons in Single InAs Quantum Dots

    NASA Astrophysics Data System (ADS)

    Ma, Shan-Shan; Dou, Xiu-Ming; Chang, Xiu-Ying; Sun, Bao-Quan; Xiong, Yong-Hua; Niu, Zhi-Chuan; Ni, Hai-Qiao

    2009-11-01

    By using polarization-resolved photoluminescence spectra, we study the electron spin relaxation in single InAs quantum dots (QDs) with the configuration of positively charged excitons X+ (one electron, two holes). The spin relaxation rate of the hot electrons increases with the increasing energy of exciting photons. For electrons localized in QDs the spin relaxation is induced by hyperfine interaction with the nuclei. A rapid decrease of polarization degree with increasing temperature suggests that the spin relaxation mechanisms are mainly changed from the hyperfine interaction with nuclei into an electron-hole exchange interaction.

  6. Optimized quantum sensing with a single electron spin using real-time adaptive measurements.

    PubMed

    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. PMID:26571007

  7. 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.

  8. 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).

  9. High-selectivity detection of single nuclear spins using rotary echo on a nitrogen-vacancy center in diamond

    NASA Astrophysics Data System (ADS)

    Mkhitaryan, Vagharsh; Dobrovitski, Viatcheslav

    2014-03-01

    The properties of the nitrogen-vacancy (NV) centers in diamond make them an excellent tool for nanoscale spin detection and sensing, capable of detecting individual nuclear spins located 0.5-1 nm away. However, the selectivity of the current methods is limited. We show that the rotating-frame control of the NV center's electron spin can improve the sensing selectivity 10-1000 times in comparison with the existing methods. We employ periodically changing Rabi driving (multiple rotary echo) with a precisely chosen period, corresponding to the precession of the given nuclear spin. The rotary echo decouples the NV center from most nuclear spins, efficiently protecting coherence. At the same time, the given nuclear spin, whose precession fits a stringent resonance condition, does not decouple, and can be detected by its decohering impact on the NV spin. We evaluate the resolution and sensitivity of this detection scheme analytically, and verify the results by numerical simulations.

  10. Electric-field-controlled spin reversal in a quantum dot with ferromagnetic contacts

    NASA Astrophysics Data System (ADS)

    Hauptmann, J. R.; Paaske, J.; Lindelof, P. E.

    2008-05-01

    Manipulation of the spin states of a quantum dot by purely electrical means is a highly desirable property of fundamental importance for the development of spintronic devices such as spin filters, spin transistors and single spin memories as well as for solid-state qubits. An electrically gated quantum dot in the Coulomb blockade regime can be tuned to hold a single unpaired spin-1/2, which is routinely spin polarized by an applied magnetic field. Using ferromagnetic electrodes, however, the quantum dot becomes spin polarized by the local exchange field. Here, we report on the experimental realization of this tunnelling-induced spin splitting in a carbon-nanotube quantum dot coupled to ferromagnetic nickel electrodes with a strong tunnel coupling ensuring a sizeable exchange field. As charge transport in this regime is dominated by the Kondo effect, we can use this sharp many-body resonance to read off the local spin polarization from the measured bias spectroscopy. We demonstrate that the exchange field can be compensated by an external magnetic field, thus restoring a zero-bias Kondo resonance, and we demonstrate that the exchange field itself, and hence the local spin polarization, can be tuned and reversed merely by tuning the gate voltage.

  11. 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.

  12. Transverse target single-spin asymmetry in inclusive electroproduction of charged pions and kaons

    NASA Astrophysics Data System (ADS)

    Airapetian, A.; Akopov, N.; Akopov, Z.; Aschenauer, E. C.; Augustyniak, W.; Avakian, R.; Avetissian, A.; Avetisyan, E.; Belostotski, S.; Bianchi, N.; Blok, H. P.; Borissov, A.; Bowles, J.; Bryzgalov, V.; Burns, J.; Capiluppi, M.; Capitani, G. P.; Cisbani, E.; Ciullo, G.; Contalbrigo, M.; Dalpiaz, P. F.; Deconinck, W.; De Leo, R.; De Nardo, L.; De Sanctis, E.; Diefenthaler, M.; Di Nezza, P.; Dren, M.; Ehrenfried, M.; Elbakian, G.; Ellinghaus, F.; Fabbri, R.; Fantoni, A.; Felawka, L.; Frullani, S.; Gabbert, D.; Gapienko, G.; Gapienko, V.; Gavrilov, G.; Gharibyan, V.; Giordano, F.; Gliske, S.; Golembiovskaya, M.; Hadjidakis, C.; Hartig, M.; Hasch, D.; Hillenbrand, A.; Hoek, M.; Holler, Y.; Hristova, I.; Ivanilov, A.; Jackson, H. E.; Joosten, S.; Kaiser, R.; Karyan, G.; Keri, T.; Kinney, E.; Kisselev, A.; Korotkov, V.; Kozlov, V.; Kravchenko, P.; Krivokhijine, V. G.; Lagamba, L.; Lapiks, L.; Lehmann, I.; Lenisa, P.; Lpez Ruiz, A.; Lorenzon, W.; Ma, B.-Q.; Mahon, D.; Makins, N. C. R.; Manaenkov, S. I.; Mao, Y.; Marianski, B.; Martnez de la Ossa, A.; Marukyan, H.; Miller, C. A.; Miyachi, Y.; Movsisyan, A.; Murray, M.; Mussgiller, A.; Nappi, E.; Naryshkin, Y.; Negodaev, M.; Nowak, W.-D.; Pappalardo, L. L.; Perez-Benito, R.; Petrosyan, A.; Raithel, M.; Reimer, P. E.; Reolon, A. R.; Riedl, C.; Rith, K.; Rosner, G.; Rostomyan, A.; Rubin, J.; Ryckbosch, D.; Salomatin, Y.; Sanftl, F.; Schfer, A.; Schnell, G.; Seitz, B.; Shibata, T.-A.; Shutov, V.; Stancari, M.; Statera, M.; Steffens, E.; Steijger, J. J. M.; Stewart, J.; Stinzing, F.; Taroian, S.; Terkulov, A.; Truty, R.; Trzcinski, A.; Tytgat, M.; Van Haarlem, Y.; Van Hulse, C.; Veretennikov, D.; Vikhrov, V.; Vilardi, I.; Wang, S.; Yaschenko, S.; Ye, Z.; Yen, S.; Yu, W.; Zagrebelnyy, V.; Zeiler, D.; Zihlmann, B.; Zupranski, P.

    2014-01-01

    Single-spin asymmetries were investigated in inclusive electroproduction of charged pions and kaons from transversely polarized protons at the HERMES experiment. The asymmetries were studied as a function of the azimuthal angle ? about the beam direction between the target-spin direction and the hadron production plane, the transverse hadron momentum PT relative to the direction of the incident beam, and the Feynman variable xF. The sin ? amplitudes are positive for ?+ and K+, slightly negative for ?- and consistent with zero for K-, with particular PT but weak xF dependences. Especially large asymmetries are observed for two small subsamples of events, where also the scattered electron was recorded by the spectrometer.

  13. Spin filtering and entanglement swapping through coherent evolution of a single quantum dot.

    PubMed

    Coello, Jose Garcia; Bayat, Abolfazl; Bose, Sougato; Jefferson, John H; Creffield, Charles E

    2010-08-20

    We exploit the nondissipative dynamics of a pair of electrons in a large square quantum dot to perform singlet-triplet spin measurement through a single charge detection and show how this may be used for entanglement swapping and teleportation. The method is also used to generate the Affleck-Kennedy-Lieb-Tasaki ground state, a further resource for quantum computation. We justify, and derive analytic results for, an effective charge-spin Hamiltonian which is valid over a wide range of parameters and agrees well with exact numerical results of a realistic effective-mass model. Our analysis also indicates that the method is robust to the choice of dot-size and initialization errors, as well as decoherence. PMID:20868084

  14. Polytype control of spin qubits in silicon carbide

    NASA Astrophysics Data System (ADS)

    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.

    2013-05-01

    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.

  15. Temperature dependence of electron-spin relaxation in a single InAs quantum dot at zero applied magnetic field

    NASA Astrophysics Data System (ADS)

    Dou, X. M.; Sun, B. Q.; Jiang, D. S.; Ni, H. Q.; Niu, Z. C.

    2012-03-01

    The temperature-dependent electron spin relaxation of positively charged excitons in a single InAs quantum dot was measured by time-resolved photoluminescence spectroscopy at zero applied magnetic fields. The experimental results show that the electron-spin relaxation is clearly divided into two different temperature regimes: (i) at T < 50 K, spin relaxation depends on the dynamical nuclear spin polarization and is approximately temperature-independent, as predicted by Merkulov et al. [Phys. Rev. B 65, 205309 (2002)] (ii) T > about 50 K, spin relaxation speeds up with increasing temperature. A model of a two longitudinal optical phonon scattering process coupled with hyperfine interaction is proposed to account for the accelerated electron spin relaxation at higher temperatures.

  16. Elasticity of Single-Crystal Ferropericlase across the Spin Transition in the Lower Mantle

    NASA Astrophysics Data System (ADS)

    Yang, J.; Tong, X.; Lin, J. F.; Okuchi, T.; Tomioka, N.

    2014-12-01

    Recent experimental and theoretical studies on the lower-mantle ferropericlase have demonstrated that its physical and chemical properties can be affected by the spin transition, which in turn can affect our understanding of deep-Earth seismic structures, geochemistry, and geodynamics. The sound velocities of ferropericlase at lower-mantle pressures have been reported using various techniques including Brillouin Light Scattering (BLS), Impulsive Stimulate Light Scattering (ISS), Inelastic X-ray Scattering (IXS), and Nuclear Resonant Inelastic X-ray Scattering [1,2,3]. However, the compressional wave and shear wave velocities have never been measured simultaneously up to lower mantle conditions to solve for full elastic constants of ferropericlase, C11, C12 and C44 via Christoffel's equations. Thus far, the effects of the spin transition on elasticity of ferropericlase remains highly debated. Using the combinations of experimental results from BLS and ISS measurements in the Mineral Physics Lab at the University of Texas at Austin, we have directly measured Vp and Vs of ferropericlase (Mg0.92Fe0.08)O simultaneously along [100] and [110] crystallographic axes up to megabar pressures. These results permit the derivation of reliable full elastic constants and the modeling of the elastic and seismic properties in the high-spin, low-spin and mixed-spin states. Single-crystal X-ray diffraction experiments were also performed to provide the equation of state parameters of ferropericlase for the modelling. The compressional wave velocities from ISS measurements show significant softening, while shear wave velocities from BLS experiments were only slightly affected by the spin transition. Using thermoelastic modelling [4], we will discuss the effects of the spin transition on elastic constants, sound velocities, elastic anisotropies, and seismic parameters of ferropericlase at lower-mantle pressure-temperature conditions. These results are compared with seismic observations of the deep lower mantle in order to better understand seismic signatures and mineralogical models of the lower mantle. References:1. Antonangeli, D., et al., 2011, Science 331, 64 2.Marquardt, H., et al., 2009, Science 324, 224. 3. Crowhurst, J., et al., 2008, Science 319, 451. 4.Wu, Z.Q., et al., 2013, PRL 110, 228501.

  17. Implementation of dynamically corrected gates on a single electron spin in diamond.

    PubMed

    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. PMID:24580578

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. Hardy's paradox tested in the spin-orbit Hilbert space of single photons

    NASA Astrophysics Data System (ADS)

    Karimi, Ebrahim; Cardano, Filippo; Maffei, Maria; de Lisio, Corrado; Marrucci, Lorenzo; Boyd, Robert W.; Santamato, Enrico

    2014-03-01

    We test experimentally the quantum "paradox" proposed by L. Hardy [Phys. Rev. Lett. 71, 1665 (1993), 10.1103/PhysRevLett.71.1665] by using single photons instead of photon pairs. This is achieved by addressing two compatible degrees of freedom of the same particle, namely, its spin angular momentum, determined by the photon polarization, and its orbital angular momentum, a property related to the optical transverse mode. Because our experiment involves a single particle, we cannot use locality to logically enforce noncontextuality, which must therefore be assumed based only on the observables' compatibility. On the other hand, our single-particle experiment can be implemented more simply and allows larger detection efficiencies than typical two-particle ones, with a potential future advantage in terms of closing the detection loopholes.

  3. A mononuclear transition metal single-molecule magnet in a nuclear spin-free ligand environment.

    PubMed

    Fataftah, Majed S; Zadrozny, Joseph M; Rogers, Dylan M; Freedman, Danna E

    2014-10-01

    The high-spin pseudotetrahedral complex [Co(C3S5)2](2-) exhibits slow magnetic relaxation in the absence of an applied dc magnetic field, one of a small number of mononuclear complexes to display this property. Fits to low-temperature magnetization data indicate that this single-molecule magnet possesses a very large and negative axial zero-field splitting and small rhombicity. The presence of single-molecule magnet behavior in a zero-nuclear spin ligand field offers the opportunity to investigate the potential for this molecule to be a qubit, the smallest unit of a quantum information processing (QIP) system. However, simulations of electron paramagnetic resonance (EPR) spectra and the absence of EPR spectra demonstrate that this molecule is unsuitable as a qubit due to the same factors that promote single molecule magnet behavior. We discuss the influence of rhombic and axial zero-field splitting on QIP applications and the implications for future molecular qubit syntheses. PMID:25198379

  4. Magnetoelectric effects and valley-controlled spin quantum gates in transition metal dichalcogenide bilayers

    SciTech Connect

    Gong, Zhirui; Liu, G. B.; Yu, Hongyi; Xiao, Di; Cui, Xiaodong; Xu, Xiaodong; Yao, Wang

    2013-01-01

    In monolayer group-VI transition metal dichalcogenides, charge carriers have spin and valley degrees of freedom, both associated with magnetic moments. On the other hand, the layer degree of freedom in multilayers is associated with electrical polarization. Here we show that transition metal dichalcogenide bilayers offer an unprecedented platform to realize a strong coupling between the spin, valley and layer pseudospin of holes. Such coupling gives rise to the spin Hall effect and spin-dependent selection rule for optical transitions in inversion symmetric bilayer and leads to a variety of magnetoelectric effects permitting quantum manipulation of these electronic degrees of freedom. Oscillating electric and magnetic fields can both drive the hole spin resonance where the two fields have valley-dependent interference, making an interplay between the spin and valley as information carriers possible for potential valley-spintronic applications. We show how to realize quantum gates on the spin qubit controlled by the valley bit.

  5. Strain-controlled spin and charge pumping in graphene devices via spin-orbit coupled barriers

    NASA Astrophysics Data System (ADS)

    Mohammadkhani, Ramin; Abdollahipour, Babak; Alidoust, Mohammad

    2015-09-01

    We theoretically propose a graphene-based adiabatic quantum pump with intrinsic spin-orbit coupling (SOC) subject to strain where two time-dependent extrinsic spin-orbit coupled barriers drive spin and charge currents. We study three differing operation modes where i) location, ii) chemical potential, and iii) SOC of the two barriers oscillate periodically and out of phase around their equilibrium states. Our results demonstrate that the amplitude of adiabatically pumped currents highly depends on the considered operation mode. We find that such a device operates with highest efficiency and in a broader range of parameters where the barriers' chemical potential drives the quantum pump. Our results also reveal that by introducing strain to the system, one can suppress or enhance the charge and spin currents separately, depending on the strain direction.

  6. 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.

  7. Remotely piloted research vehicle evaluation of advanced control system effects on spins

    NASA Technical Reports Server (NTRS)

    Petersen, K. L.

    1976-01-01

    Special functions of an advanced control system were investigated for effects on spin entries and recoveries utilizing a 3/8-scale model of the F-15 airplane as a remotely piloted research vehicle (RPRV). Telemetry uplinks and downlinks were used with a ground-based digital computer to mechanize the RPRV control system for spin tests in flight. Results from the model RPRV flight tests and from a real time digital spin simulation were used to evaluate the F-15 stall inhibiter and an automatic spin recovery system developed for the RPRV model

  8. Hyperon Polarization and Single Spin Left-Right Asymmetry in Inclusive Production Processes at High Energies

    SciTech Connect

    Zuo-tang, L.; Boros, C.; Boros, C.

    1997-11-01

    It is shown that the polarization of hyperons observed in high energy collisions using unpolarized hadron beams and unpolarized nucleon or nuclear targets is closely related to the left-right asymmetries observed in single spin inclusive hadron production processes. The relationship is most obvious for the production of the hyperons which have only one common valence quark with the projectile. Examples of this kind are given. Further implications of the existence of large polarization for a hyperon which has two valence quarks in common with the projectile and their consequences are discussed. A comparison with the available data is made. Further tests are suggested. {copyright} {ital 1997} {ital The American Physical Society}

  9. 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

  10. Single-spin asymmetry in pp and pA-collisions

    NASA Astrophysics Data System (ADS)

    Abramov, V. V.

    2016-02-01

    Experimental data on the transverse single-spin asymmetry AN in the collisions of polarized protons with protons and nuclear targets are analyzed. The existing data are compared with predictions from the chromomagnetic polarization of quarks (CPQ) model for the processes of ?, K, p and antiproton production in the inclusive reactions. The results of An calculations for the above processes are presented in the following kinematic region: 8.77 ? ?s ? 500 GeV, 0 < xF ? 0.83, 0 ? pT ? 9 GeV/c. Predictions of the CPQ model can be used for planning of experiments SPASCHARM(IHEP), SPD(JINR), STAR and PHENIX.

  11. 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 Schrdinger 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.

  12. 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.

  13. Propeller swirl effect on single-engine general-aviation aircraft stall-spin tendencies

    NASA Technical Reports Server (NTRS)

    Katz, Joseph; Feistel, Terry W.

    1987-01-01

    An investigation is conducted of the effect of a single engine, untapered low wing general aviation aircraft propeller's swirl on the craft's stall pattern. The asymmetrical character of the propeller's swirl can trigger an early stall of one of the wings, aggravating the spin-entry condition. It is shown that the combination of this propeller-induced effect with adverse sideslip can result in large and abrupt changes in the rolling moment, in such conditions as uncoordinated low speed turning maneuvers where the pilot yaws the aircraft with wings level, rather than rolling it.

  14. 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 Inelastic Scattering, the Drell-Yan process, and in inclusive hadron production and dijet correlations at hadron colliders. There were not only discussions on possible interpretations of the existing SSA data, but also on the future observables for the ongoing experiments as well as for planned experiments (such as RHIC II and eRHIC). On the theory side, the talks ranged from overviews and descriptions of the fundamental aspects of SSAs, to presentations of detailed phenomenological studies. All of the talks attracted much interest and initiated active discussions. Directions for future measurements were pointed out, in particular for studies at RHIC. Also, significant theoretical advances were made that may tie together some of the currently proposed mechanisms for single-spin asymmetries. This was a very successful workshop. It stimulated many discussions and new collaborations.

  15. Molecular Quantum Spintronics: Supramolecular Spin Valves Based on Single-Molecule Magnets and Carbon Nanotubes

    PubMed Central

    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 TbPc2 (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 (TB ~ 1 K) of isolated TbPc2 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

  16. 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 ? s by dressing with a ? /2 ? =581 2 kHz mechanical Rabi field. Furthermore, we develop a model that quantitatively predicts the relationship between ? 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 ? accessed here. We show that amplitude noise in ? will dominate the dephasing for larger driving fields.

  17. 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.

  18. 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.

  19. Coherent Control of a Nitrogen-Vacancy Center Spin Ensemble with a Diamond Mechanical Resonator

    NASA Astrophysics Data System (ADS)

    Guo, F.; Macquarrie, E. R.; Gosavi, T. A.; Moehle, A. M.; Jungwirth, N. R.; Bhave, S. A.; Fuchs, G. D.

    2015-03-01

    In contrast to the traditional coherent control of the nitrogen vacancy (NV) center in diamond's triplet spin state with ac magnetic fields, we recently demonstrated that gigahertz-frequency lattice strain resonant with the ms= +1 to -1 spin state splitting can also be used to drive spin transitions. We present coherent spin control over NV center ensembles with a bulk-mode mechanical microresonator that generates large amplitude ac stress within the diamond substrate. Using these structures, we mechanically drive coherent Rabi oscillations between the -1 and +1 states. We also accurately model the Rabi dephasing with a combination of a spatially inhomogeneous mechanical driving field and magnetic noise from a fluctuating spin bath. Understanding mechanically driven dynamics in spin ensembles could have applications in sensing and quantum optomechanics where interactions can be enhanced by the number of spins. Moreover, these results demonstrate coherent mechanical control of the magnetically forbidden -1 to +1 spin transition, thus closing the loop on NV center ground state spin control and enabling the creation of a coherent ?-system within the NV center ground state. We gratefully acknowledge support from the ONR.

  20. Towards single-molecule NMR detection and spectroscopy using single spins in diamond

    NASA Astrophysics Data System (ADS)

    Perunicic, V. S.; Hall, L. T.; Simpson, D. A.; Hill, C. D.; Hollenberg, L. C. L.

    2014-02-01

    Nanomagnetometry using the nitrogen-vacancy (NV) center in diamond has attracted a great deal of interest due to its unique combination of room temperature operation, nanoscale resolution, and high sensitivity. One of the important goals for nanomagnetometry is to be able to detect nanoscale nuclear magnetic resonance (NMR) in individual molecules. Our theoretical analysis details a method by which a single molecule on the surface of diamond, with characteristic NMR frequencies, can be detected using a proximate NV center on a time scale of an order of seconds with nanometer precision. We perform spatiotemporal resolution optimization and subsequently outline paths to greater sensitivity. Our method is suitable for application in low and relatively inhomogeneous background magnetic fields in contrast to both conventional liquid and solid state NMR spectroscopy.

  1. 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. PMID:26460612

  2. Rotary balance data for a single-engine trainer design for an angle-of-attack range of 8 deg to 90 deg. [conducted in langely spin tunnel

    NASA Technical Reports Server (NTRS)

    Pantason, P.; Dickens, W.

    1979-01-01

    Aerodynamic characteristics obtained in a rotational flow environment utilizing a rotary balance located in the Langley spin tunnel are presented in plotted form for a 1/6 scale, single engine trainer airplane model. The configurations tested included the basic airplane, various wing leading edge devices, elevator, aileron and rudder control settings as well as airplane components. Data are presented without analysis for an angle of attack range of 8 to 90 degrees and clockwise and counter-clockwise rotations.

  3. 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.

  4. Spin-controlled ultrafast vertical-cavity surface-emitting lasers

    NASA Astrophysics Data System (ADS)

    Hpfner, Henning; Lindemann, Markus; Gerhardt, Nils C.; Hofmann, Martin R.

    2014-05-01

    Spin-controlled semiconductor lasers are highly attractive spintronic devices providing characteristics superior to their conventional purely charge-based counterparts. In particular, spin-controlled vertical-cavity surface emitting lasers (spin-VCSELs) promise to offer lower thresholds, enhanced emission intensity, spin amplification, full polarization control, chirp control and ultrafast dynamics. Most important, the ability to control and modulate the polarization state of the laser emission with extraordinarily high frequencies is very attractive for many applications like broadband optical communication and ultrafast optical switches. We present a novel concept for ultrafast spin-VCSELs which has the potential to overcome the conventional speed limitation for directly modulated lasers by the relaxation oscillation frequency and to reach modulation frequencies significantly above 100 GHz. The concept is based on the coupled spin-photon dynamics in birefringent micro-cavity lasers. By injecting spin-polarized carriers in the VCSEL, oscillations of the coupled spin-photon system can by induced which lead to oscillations of the polarization state of the laser emission. These oscillations are decoupled from conventional relaxation oscillations of the carrier-photon system and can be much faster than these. Utilizing these polarization oscillations is thus a very promising approach to develop ultrafast spin-VCSELs for high speed optical data communication in the near future. Different aspects of the spin and polarization dynamics, its connection to birefringence and bistability in the cavity, controlled switching of the oscillations, and the limitations of this novel approach will be analysed theoretically and experimentally for spin-polarized VCSELs at room temperature.

  5. 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.

  6. 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.

  7. Magnetization tunneling in high-symmetry single-molecule magnets: Limitations of the giant spin approximation

    NASA Astrophysics Data System (ADS)

    Wilson, A.; Lawrence, J.; Yang, E.-C.; Nakano, M.; Hendrickson, D. N.; Hill, S.

    2006-10-01

    Electron paramagnetic resonance (EPR) studies of a Ni4 single-molecule magnet (SMM) yield the zero-field-splitting (ZFS) parameters D , B40 , and B44 , based on the giant spin approximation (GSA) with S=4 ; B44 is responsible for the magnetization tunneling in this SMM. Experiments on an isostructural Ni-doped Zn4 crystal establish the NiII ion ZFS parameters. The fourth-order ZFS parameters in the GSA arise from the interplay between the Heisenberg interaction J?1?2 and the second-order single-ion anisotropy, giving rise to mixing of higher-lying S?4 states into the S=4 state. Consequently, J directly influences the ZFS in the ground state, enabling its determination by EPR.

  8. Controlling spin-wave propagation with Oersted fields

    NASA Astrophysics Data System (ADS)

    Vogt, K.; Hillebrands, B.; Schultheiss, H.; Pearson, J. E.; Fradin, F. Y.; Bader, S. D.; Hoffmann, A.

    2013-03-01

    The goal of magnon spintronics is to utilize the coherent propagation of spin waves for low-power data processing. Spin waves carry angular momentum and can transport spin information over distances much larger than the spin diffusion length of metals. However, in thin magnetic films the highly anisotropic dispersion relation leads to strong changes in the spin-wave energy for different angles between their propagation direction and the magnetization orientation. Consequently, spin waves only travel along a straight path if the magnetization direction is fixed by a global external magnetic field. We demonstrate that locally rotating magnetic fields generated via electric current pulses allow to vary the propagation direction of spin waves. Using spatially resolved Brillouin light scattering microscopy the propagation behavior was directly verified.[2] We have modeled the current generated magnetic fields with a finite element code and calculated the magnetic response using micro magnetic simulations. Financial support by the Carl-Zeiss-Stiftung is acknowledged. Work at Argonne and use of the Center of Nanoscale Materials is supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE

  9. 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.

  10. Efficient route to high-bandwidth nanoscale magnetometry using single spins in diamond.

    PubMed

    Puentes, Graciana; Waldherr, Gerald; Neumann, Philipp; Balasubramanian, Gopalakrishnan; Wrachtrup, Jrg

    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 ?B ? 1/T (Heisenberg scaling) rather than as the inverse of the square root of T, with ?B = ?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 ?B ? 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

  11. 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.

  12. Spin-wave storage using chirped control fields in atomic frequency comb-based quantum memory

    NASA Astrophysics Data System (ADS)

    Min?, Ji?; Sangouard, Nicolas; Afzelius, Mikael; de Riedmatten, Hugues; Gisin, Nicolas

    2010-10-01

    It has been shown that an inhomogeneously broadened optical transition shaped into an atomic frequency comb can store a large number of temporal modes of the electromagnetic field at the single-photon level without the need to increase the optical depth of the storage material. The readout of light modes is made efficient thanks to the rephasing of the optical-wavelength coherence similar to photon-echo-type techniques, and the reemission time is given by the comb structure. For on-demand readout and long storage times, two control fields are used to transfer the optical coherence back and forth into a spin wave. Here, we present a detailed analysis of the spin-wave storage based on chirped adiabatic control fields. In particular, we verify that chirped fields require significantly weaker intensities than ? pulses. The price to pay is a reduction of the multimode storage capacity that we quantify for realistic material parameters associated with solids doped with rare-earth-metal ions.

  13. 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.

  14. 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

  15. Harnessing spin precession with dissipation.

    PubMed

    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

  16. Gate-control of spin-motive force and spin-torque in Rashba SOC systems

    NASA Astrophysics Data System (ADS)

    Son Ho, Cong; Jalil, Mansoor B. A.; Ghee Tan, Seng

    2015-12-01

    The introduction of a strong Rashba spin–orbit coupling has been predicted to enhance the spin motive force (SMF) (see Kim et al 2012 Phys. Rev. Lett. 108 217202). In this work, we predict further enhancement of the SMF by time modulation of the Rashba coupling {α }{{R}}, which induces an additional electric field {E}dR={\\dot{α }}{{R}}{m}{{e}}/e{{\\hslash }}(\\hat{z}× m). When the modulation frequency is higher than the magnetization precessing frequency, the amplitude of this field is significantly larger than previously predicted results. Correspondingly, the spin torque on the magnetization is also effectively enhanced. We also suggest a biasing scheme to achieve rectification of SMF, i.e., by application of a square wave voltage at the resonant frequency. Finally, we numerically estimate the resulting spin torque field arising from a Gaussian pulse time modulation of {α }{{R}}.

  17. Fast deterministic switching in orthogonal spin torque devices via the control of the relative spin polarizations

    SciTech Connect

    Park, Junbo; Buhrman, R. A.; Ralph, D. C.; Kavli Institute at Cornell, Ithaca, New York 14853

    2013-12-16

    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, C{sub P} = P{sub IPP}/P{sub OPP}, results in deterministic switching of the free layer without over-rotation (360° rotation). By using spin torque asymmetry to realize an enhanced effective P{sub IPP}, 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 C{sub P} required to attain deterministic switching, while retaining low critical switching current, I{sub p} ∼ 500 μA.

  18. Controlling orbital-selective Kondo effects in a single molecule through coordination chemistry

    NASA Astrophysics Data System (ADS)

    Tsukahara, Noriyuki; Minamitani, Emi; Kim, Yousoo; Kawai, Maki; Takagi, Noriaki

    2014-08-01

    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 dz2 and the degenerate d? 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 Fe2+ 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 dz2 and NO 5? and 2?* 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 Fe2+ 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.

  19. Controlling orbital-selective Kondo effects in a single molecule through coordination chemistry.

    PubMed

    Tsukahara, Noriyuki; Minamitani, Emi; Kim, Yousoo; Kawai, Maki; Takagi, Noriaki

    2014-08-01

    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(z)(2) and the degenerate d? 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(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(z)(2) and NO 5? and 2?* 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(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. PMID:25106595

  20. 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 d? 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 5? and 2?* 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.

  1. Coupling and control in coherently driven and asymmetrically synchronized hybrid electron-nuclear spin system

    NASA Astrophysics Data System (ADS)

    Berec, V.

    2016-02-01

    We study the coupling and control adaptation of a hybrid electron-nuclear spin system using the laser mediated proton beam in MeV energy regime. The asymmetric control mechanism is based on exact optimization of both: the measure of exchange interaction and anisotropy of the hyperfine interaction induced in the resonance with optimal channeled protons (CP) superfocused field, allowing manipulation over arbitrary localized spatial centers while addressing only the electron spin. Using highly precise and coherent proton channeling regime we have obtained efficient pulse shaping separator technique aimed for spatio-temporal engineering of quantum states, introducing a method for control of nuclear spins, which are coupled via anisotropic hyperfine interactions in isolated electron spin manifold, without radio wave (RW) pulses. The presented method can be efficiently implemented in synchronized spin networks with the purpose to facilitate preservation and efficient transfer of experimentally observed quantum particle states, contributing to the overall background noise reduction.

  2. Quantum control of spin correlations in ultracold lattice gases

    NASA Astrophysics Data System (ADS)

    Hauke, P.; Sewell, R. J.; Mitchell, M. W.; Lewenstein, M.

    2013-02-01

    We describe a technique for the preparation of quantum spin correlations in a lattice gas of ultracold atoms using an atom-light interaction of the kind routinely employed in quantum spin polarization spectroscopy. Our method is based on entropic cooling via quantum nondemolition measurement and feedback, and allows the creation and detection of quantum spin correlations, as well as a certain degree of multipartite entanglement which we verify using a generalization of the entanglement witness described previously M. Cramer , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.106.020401 106, 020401 (2011). We illustrate the procedure with examples drawn from the bilinear-biquadratic Hamiltonian, which can be modeled by a one-dimensional chain of spin-1 atoms.

  3. 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

  4. 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.

  5. Competition between electric field and magnetic field noise in the decoherence of a single spin in diamond

    NASA Astrophysics Data System (ADS)

    Jamonneau, P.; Lesik, M.; Tetienne, J. P.; Alvizu, I.; Mayer, L.; Dréau, A.; Kosen, S.; Roch, J.-F.; Pezzagna, S.; Meijer, J.; Teraji, T.; Kubo, Y.; Bertet, P.; Maze, J. R.; Jacques, V.

    2016-01-01

    We analyze the impact of electric field and magnetic field fluctuations in the decoherence of the electronic spin associated with a single nitrogen-vacancy (NV) defect in diamond. To this end, we tune the amplitude of a magnetic field in order to engineer spin eigenstates protected either against magnetic noise or against electric noise. The competition between these noise sources is analyzed quantitatively by changing their relative strength through modifications of the host diamond material. This study provides significant insights into the decoherence of the NV electronic spin, which is valuable for quantum metrology and sensing applications.

  6. Control of spin dynamics in a two-dimensional electron gas by electromagnetic dressing

    NASA Astrophysics Data System (ADS)

    Pervishko, A. A.; Kibis, O. V.; Morina, S.; Shelykh, I. A.

    2015-11-01

    We solved the Schrödinger problem for a two-dimensional electron gas (2DEG) with the Rashba spin-orbit interaction in the presence of a strong high-frequency electromagnetic field (dressing field). The found eigenfunctions and eigenenergies of the problem are used to describe the spin dynamics of the dressed 2DEG within the formalism of the density matrix response function. Solving the equations of spin dynamics, we show that the dressing field can switch the spin relaxation in the 2DEG between the cases corresponding to the known Elliott-Yafet and D'yakonov-Perel' regimes. As a result, the spin properties of the 2DEG can be tuned by a high-frequency electromagnetic field. The present effect opens an unexplored way for controlling the spin with light and, therefore, forms the physical prerequisites for creating light-tuned spintronics devices.

  7. Single-walled carbon nanotube device fabrication using spin coating of dispersions

    NASA Astrophysics Data System (ADS)

    Hummel, Paul Jeremy

    This research looks at ways to utilize already synthesized carbon nanotubes (CNT) to manufacture electrical connections using current tools and fabrication methods employed in the semiconductor industry. Purchased single-walled carbon nanotubes (SWNT) are separated and placed in suspension using poly(sodium styrene sulfonate) (PSS). The PSS non-covalently bonds to the SWNTs, causing them to repel each other due to the negative charge of the PSS. The suspension of SWNTs is spin coated over a processed silicon (Si) wafer with fabricated trenches. A Si wafer with a top silicon dioxide (SiO 2) layer is spin coated with Shipley 1827 photoresist. UV light is used to expose areas to the photoresist, creating trench areas. After removal of the exposed areas of the photoresist, trenches are etched into the SiO 2 layer with a buffered oxide etch (BOE) solution of hydrofluoric acid. The suspension of SWNTs is spin coated over the processed Si wafer. The wafer is placed on a hot plate at 115 C to slowly evaporate the water from the SWNT suspension. As the water evaporates, the SWNTs remain on the surface of the Si wafer or gather in the trenches. Finally, the photoresist is removed, lifting off all of the SWNTs that are not in the trenches. Several trenches have a sufficient fill rate to allow IV characteristics to be performed. A Keithley probe station is used to measure the resistance of the SWNT composite material in the trench. These results, 47.3 kO, are similar to other fabricated SWNT/polyelectrolyte thin films, showing that the method presented can be used to simplify the process of fabricating SWNT composite wires. Raman spectroscopy is also used to determine if the SWNTs in the SWNT composite structure are aligned in any direction. There is no preferential orientation of the SWNTs in the structure, rather the SWNTs appeared to be randomly oriented in all directions.

  8. Rapid gravitational wave parameter estimation with a single spin: Systematic uncertainties in parameter estimation with the SpinTaylorF2 approximation

    NASA Astrophysics Data System (ADS)

    Miller, B.; O'Shaughnessy, R.; Littenberg, T. B.; Farr, B.

    2015-08-01

    Reliable low-latency gravitational wave parameter estimation is essential to target limited electromagnetic follow-up facilities toward astrophysically interesting and electromagnetically relevant sources of gravitational waves. In this study, we examine the trade-off between speed and accuracy. Specifically, we estimate the astrophysical relevance of systematic errors in the posterior parameter distributions derived using a fast-but-approximate waveform model, SpinTaylorF2 (stf2), in parameter estimation with lalinference_mcmc. Though efficient, the stf2 approximation to compact binary inspiral employs approximate kinematics (e.g., a single spin) and an approximate waveform (e.g., frequency domain versus time domain). More broadly, using a large astrophysically motivated population of generic compact binary merger signals, we report on the effectualness and limitations of this single-spin approximation as a method to infer parameters of generic compact binary sources. For most low-mass compact binary sources, we find that the stf2 approximation estimates compact binary parameters with biases comparable to systematic uncertainties in the waveform. We illustrate by example the effect these systematic errors have on posterior probabilities most relevant to low-latency electromagnetic follow-up: whether the secondary has a mass consistent with a neutron star (NS); whether the masses, spins, and orbit are consistent with that neutron star's tidal disruption; and whether the binary's angular momentum axis is oriented along the line of sight.

  9. Electric field controlled spin- and valley-polarized edge states in silicene with extrinsic Rashba effect

    NASA Astrophysics Data System (ADS)

    Yu, Zhiming; Pan, Hui; Yao, Yugui

    2015-10-01

    In the presence of extrinsic Rashba spin-orbit coupling, we find that silicene can host a quantum anomalous Hall state with spin- and valley-polarized edge states, which can be effectively controlled by the exchange field and electric field. In this state, a pair of nontrivial edge states reside in one specific valley and have a strong but opposite spin polarization. A distinctive feature of this state is that both of the spin and valley indexes of the edge states can be switched by reversing the electric field. We also present a microscopic mechanism for the origin of this state. Our findings provide an efficient way to control the topologically protected spin- and valley-polarized edge states, which is crucial for spintronics and valleytronics.

  10. Spin frequency comb echo memory controlled by a pulsed-gradient of magnetic field

    NASA Astrophysics Data System (ADS)

    Gerasimov, K. I.; Moiseev, S. A.; Morozov, V. I.; Zaripov, R. B.

    2015-03-01

    The controllable storage and on demand retrieval of the microwave pulses by using the photon echo quantum memory approach based on a spin frequency comb of inhomogeneous broadening (SFC- protocol) have been demonstrated. We have used an electron-nuclear spin ensemble of tetracyanoethylene anion radicals in toluene which has a natural periodic structure of narrow electron-spin resonance (ESR) hyperfine lines. On-demand retrieval of the stored field has been realized by using two pulses of the magnetic field gradient of an opposite polarity which hold the electron spins in a dephased excited state during the storage time. The obtained experimental results demonstrate promising properties for coherent controlling the electron-nuclear spin ensemble of radicals in liquid that could be useful for implementation of room-temperature broadband quantum memory.

  11. 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}.

  12. Quantum control of orbital and spin dynamics in diamond using ultrafast optical pulses

    NASA Astrophysics Data System (ADS)

    Heremans, F. Joseph

    2015-03-01

    Optically addressable spin defects in solid-state materials have shown great potential for applications ranging from metrology to quantum information processing. Many of these experiments require a detailed understanding of the full Hamiltonian dynamics in order to develop precise quantum control. Here we use picosecond resonant optical pulses to investigate the coherent orbital and spin dynamics of the nitrogen-vacancy (NV) center in diamond, over timescales spanning six orders of magnitude. We implement an ultrafast optical pump-probe technique to study the NV center's orbital-doublet, spin-triplet excited state at cryogenic temperatures (T < 20 K), where the excited state becomes stable and optically coherent with the ground state. This technique, coupled with optical polarization selection rules, allows us to probe the coherent orbital dynamics of the NV center's excited state. These experiments reveal dynamics on femtosecond to nanosecond timescales due to the interplay between the ground and excited state orbital levels. This all-optical technique also provides a method to dynamically control the spin state of the NV center by harnessing the excited state structure. Through studying the spin dynamics of the NV center with coherent pulses of light, we are able to rotate the spin state on sub-nanosecond timescales. Furthermore, by tuning the excited-state spin Hamiltonian with an external magnetic field, we demonstrate arbitrary-axis spin rotations through controlled unitary evolution of the spin state. Extending this to the full excited-state manifold, we develop a time-domain quantum tomography technique to precisely map the NV center's excited state Hamiltonian. These techniques generalize to other systems and can be a powerful tool in characterizing and controlling qubits in other optically addressable spin systems. This work is supported by the AFOSR and NSF.

  13. 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

  14. Longitudinal-transverse double-spin asymmetries in single-inclusive leptoproduction of hadrons

    NASA Astrophysics Data System (ADS)

    Kanazawa, K.; Metz, A.; Pitonyak, D.; Schlegel, M.

    2015-03-01

    We analyze the longitudinal-transverse double-spin asymmetry in lepton-nucleon collisions where a single hadron is detected in the final state, i.e., ? ? N? ? h X. This is a subleading-twist observable in collinear factorization, and we look at twist-3 effects in both the transversely polarized nucleon and the unpolarized outgoing hadron. Results are anticipated for this asymmetry from both HERMES and Jefferson Lab Hall A, and it could be measured as well at COMPASS and a future Electron-Ion Collider. We also perform a numerical study of the distribution term, which, when compared to upcoming experimental results, could allow one to learn about the "worm-gear"-type function g (x) as well as assess the role of quark-gluon-quark correlations in the initial-state nucleon and twist-3 effects in the fragmenting unpolarized hadron.

  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. 93Nb NMR spin echo spectroscopy in single crystal NbSe3.

    PubMed

    Suh, S; Clark, W G; Monceau, P; Thorne, R E; Brown, S E

    2008-09-26

    We report electric field induced phase displacements of the charge density wave (CDW) in a single crystal of NbSe3 using 93Nb NMR spin-echo spectroscopy. CDW polarizations in the pinned state induced by unipolar and bipolar pulses are linear and reversible up to at least E = (0.96)ET. The polarizations have a broad distribution extending up to phase angles of order 60 degrees for electric fields close to threshold. No evidence for polarizations in excess of a CDW wavelength or for a divergence in polarization near ET are observed. The results are consistent with elastic depinning models, provided that the critical regime expected in large systems is not observable. PMID:18851473

  18. Single-spin asymmetries in the leptoproduction of transversely polarized Λ hyperons

    DOE PAGESBeta

    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

  19. Scanning localized magnetic fields in microfluidic system using single spin in diamond nanocrystal.

    NASA Astrophysics Data System (ADS)

    Lim, Kangmook; Shapiro, Benjamin; Taylor, Jacob; Waks, Edo

    2015-03-01

    We demonstrate localized magnetometry using a single nitrogen vacancy (NV) center in the microfluidic devices. Our approach enables three dimensional manipulation of a magnetic object in solution with nanoscale spatial accuracy, and also enables us to orient its dipole moment. A diamond nanocrystal is integrated into the microfluidic device and serves as a local magnetic field probe. We vary the position of a magnetic object in liquid and map out its magnetic field distribution by perform continuous electron spin resonance (ESR) measurement on the NV center. These results open up the possibility for using NV centers as nanosized magnetometers with high sensitivity in microfluidic device for applications in chemical sensing, biological sensing and microscopy.

  20. Helicity asymmetry E measurement for single π0 photoproduction with a frozen spin target

    NASA Astrophysics Data System (ADS)

    Iwamoto, Hideko; CLAS Collaboration

    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 energis between 0.35 GeV to 2.4 GeV. The target was a frozen-spin butanol (C4H9OH) target, polarized at about 85%. The helicity asymmetry E for the γp→pπ0 was measured with missing-mass technique at the high statistics of about 12×106 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 Eγ 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.

  1. Single spin asymmetries in ?p??hX processes and transverse momentum dependent factorization

    NASA Astrophysics Data System (ADS)

    Anselmino, M.; Boglione, M.; D'Alesio, U.; Melis, S.; Murgia, F.; Prokudin, A.

    2014-06-01

    Some estimates for the transverse single spin asymmetry, AN, in the inclusive processes ?p??hX, given in a previous paper, are expanded and compared with new experimental data. The predictions are based on the Sivers distributions and the Collins fragmentation functions which fit the azimuthal asymmetries measured in semi-inclusive deep inelastic scattering (SIDIS) processes (?p???'hX). The factorization in terms of transverse momentum dependent distribution and fragmentation functions (TMD factorization)i.e. the theoretical framework in which SIDIS azimuthal asymmetries are analyzedis assumed to hold also for the inclusive process ?p?hX at large PT. The values of AN thus obtained agree in sign and shape with the data. Some predictions are given for future experiments.

  2. Dual gate control of bulk transport and magnetism in the spin-orbit insulator S r2Ir O4

    NASA Astrophysics Data System (ADS)

    Lu, Chengliang; Dong, Shuai; Quindeau, Andy; Preziosi, Daniele; Hu, Ni; Alexe, Marin

    2015-03-01

    The 5 d iridates have been the subject of much recent attention due to the predictions of a large array of novel electronic phases driven by twisting strong spin-orbit coupling and Hubbard correlation. As a prototype, the single-layered perovskite S r2Ir O4 was first revealed to host a Jeff=1 /2 Mott insulating state. In this material, the approximate energy scale of a variety of interactions, involving spin-orbit coupling, magnetic exchange interaction, and the Mott gap, allows close coupling among the corresponding physical excitations, opening the possibility of cross control of the physical properties. Here, we experimentally demonstrate the effective gate control of both the transport and magnetism in a S r2Ir O4 -based field effect transistor using an ionic liquid dielectric. This approach could go beyond the surface-limited field effect seen in conventional transistors, reflecting the unique aspect of the Jeff=1 /2 state. The simultaneous modulation of conduction and magnetism confirms the proposed intimate coupling of charge, orbital, and spin degrees of freedom in this oxide. These phenomena are probably related to an enhanced deviation from the ideal Jeff=1 /2 state due to the gate-promoted conduction. The present work would have important implications in modelling the unusual physics enabled by strong spin-orbit coupling and provides a new route to explore those emergent quantum phases in iridates.

  3. Photoinduced single-molecule magnet properties in a four-coordinate iron(II) spin crossover complex.

    PubMed

    Mathonire, Corine; Lin, Hsiu-Jung; Siretanu, Diana; Clrac, Rodolphe; Smith, Jeremy M

    2013-12-26

    The four-coordinate Fe(II) complex, PhB(MesIm)3Fe-N?PPh3 (1) has been previously reported to undergo a thermal spin-crossover (SCO) between high-spin (HS, S = 2) and low-spin (LS, S = 0) states. This complex is photoactive below 20 K, undergoing a photoinduced LS to HS spin state change, as determined by optical reflectivity and photomagnetic measurements. With continuous white light irradiation, 1 displays slow relaxation of the magnetization, i.e. single-molecule magnet (SMM) properties, at temperatures below 5 K. This complex provides a structural template for the design of new photoinduced mononuclear SMMs based on the SCO phenomenon. PMID:24313622

  4. 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.

  5. Migdal-Kadanoff solution of the mixed spin-1 and spin-3/2 Blume-Capel model with different single-ion anisotropies

    NASA Astrophysics Data System (ADS)

    Madani, Mohamed; Gaye, Abou; El Bouziani, Mohamed; Alrajhi, Abdelhameed

    2015-11-01

    Using the real space renormalization group theory, we investigate the alternated mixed Blume-Capel model with spins S = 1 and S = 3 / 2, on the hyper cubic lattice. First, the ground state phase diagram of the system at zero temperature is obtained on the single-ion anisotropies plane showing the same topology obtained early by other approximations. According to the different values of the single-ion anisotropies, three types of phase diagrams are obtained, with first and second order transitions; tricritical points are highlighted. Also, we note the absence of dimensional crossover between d = 2 and d = 3.

  6. Heralded generation of single photons entangled in multiple temporal modes with controllable waveforms

    NASA Astrophysics Data System (ADS)

    Gogyan, A.; Sisakyan, N.; Akhmedzhanov, R.; Malakyan, Yu

    2014-11-01

    Time-bin entangled single-photons are highly demanded for long distance quantum communication. We propose a heralded source of tunable narrowband single photons entangled in well-separated multiple temporal modes (time bins) with controllable amplitudes. The detection of a single Stokes photon generated in a cold atomic ensemble via Raman scattering of a weak write pulse heralds the preparation of one spin excitation stored within the atomic medium. A train of read laser pulses deterministically converts the atomic excitation into a single anti-Stokes photon delocalized in multi-time-bins. The waveforms of bins are well-controlled by the read pulse parameters. A scheme to measure the phase coherence across all time bins is suggested.

  7. 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, Franois; 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 ? 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. PMID:23473199

  8. Electron Spin Resonance Spectroscopic Study of Size-Controlled Ink Particles Isolated from Sepia officinalis

    NASA Astrophysics Data System (ADS)

    Toshihiko Matsuura,; Shingo Watanabe,; Sei-ichi Akutagawa,; Yuhei Shimoyama,; Takanori Kobayashi,; Yoshihiro Taya,; Takashi Ueno,

    2010-06-01

    The paramagnetic properties of size-controlled ink particles isolated from the ink sacs of Sepia officinalis were studied by electron spin resonance (ESR) spectroscopy. Both the size-controlled ink particles and synthetic melanins seemingly yielded similar ESR spectra consisting of a singlet with a slightly asymmetrical signal. However, the progressive microwave power saturation revealed a clear difference between their paramagnetic behaviors. In comparison with synthetic melanins, the ESR spectra of the ink particles readily reached saturation, indicating a long spin-lattice relaxation time. On the other hand, the ESR linewidth depended on particle size. This implies that the particle size is related to the distance between paramagnetic species in the particles. Hence, it is reasonable that the large ink particle has the weakest spin-spin interaction among these samples. The employment of the size-controlled ink particles enabled us to determine precisely the paramagnetic parameters of Sepia inks.

  9. Interdiffusion-controlled Kondo suppression of injection efficiency in metallic nonlocal spin valves

    NASA Astrophysics Data System (ADS)

    O'Brien, L.; Spivak, D.; Jeong, J. S.; Mkhoyan, K. A.; Crowell, P. A.; Leighton, C.

    2016-01-01

    Nonlocal spin valves (NLSVs) generate pure spin currents, providing unique insight into spin injection and relaxation at the nanoscale. Recently it was shown that the puzzling low temperature nonmonotonicity of the spin accumulation in all-metal NLSVs occurs due to a manifestation of the Kondo effect arising from dilute local-moment-forming impurities in the nonmagnetic material. Here it is demonstrated that precise control over interdiffusion in Fe/Cu NLSVs via thermal annealing can induce dramatic increases in this Kondo suppression of injection efficiency, observation of injector/detector separation-dependent Kondo effects in both charge and spin channels simultaneously, and, in the limit of large interdiffusion, complete breakdown of standard Valet-Fert-based models. The Kondo effect in the charge channel enables extraction of the exact interdiffusion profile, quantifying the influence of local moment density on the injection efficiency and presenting a well-posed challenge to theory.

  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. 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.

  12. 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 s 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.

  13. Coherent spin control of a nanocavity-enhanced qubit in diamond

    DOE PAGESBeta

    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

  14. 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.

  15. 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.

  16. 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.

  17. Coherent spin control of a nanocavity-enhanced qubit in diamond

    NASA Astrophysics Data System (ADS)

    Li, Luozhou; Schrder, 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??s 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.

  18. High-Fidelity Rapid Initialization and Read-Out of an Electron Spin via the Single Donor D- Charge State

    NASA Astrophysics Data System (ADS)

    Watson, T. F.; Weber, B.; House, M. G.; Bch, H.; Simmons, M. Y.

    2015-10-01

    We demonstrate high-fidelity electron spin read-out of a precision placed single donor in silicon via spin selective tunneling to either the D+ or D- charge state of the donor. By performing read-out at the stable two electron D0?D- charge transition we can increase the tunnel rates to a nearby single electron transistor charge sensor by nearly 2 orders of magnitude, allowing faster qubit read-out (1 ms) with minimum loss in read-out fidelity (98.4%) compared to read-out at the D+?D0 transition (99.6%). Furthermore, we show that read-out via the D- charge state can be used to rapidly initialize the electron spin qubit in its ground state with a fidelity of FI=99.8 %.

  19. High-Fidelity Rapid Initialization and Read-Out of an Electron Spin via the Single Donor D^{-} Charge State.

    PubMed

    Watson, T F; Weber, B; House, M G; Bch, H; Simmons, M Y

    2015-10-16

    We demonstrate high-fidelity electron spin read-out of a precision placed single donor in silicon via spin selective tunneling to either the D^{+} or D^{-} charge state of the donor. By performing read-out at the stable two electron D^{0}?D^{-} charge transition we can increase the tunnel rates to a nearby single electron transistor charge sensor by nearly 2 orders of magnitude, allowing faster qubit read-out (1ms) with minimum loss in read-out fidelity (98.4%) compared to read-out at the D^{+}?D^{0} transition (99.6%). Furthermore, we show that read-out via the D^{-} charge state can be used to rapidly initialize the electron spin qubit in its ground state with a fidelity of F_{I}=99.8%. PMID:26550896

  20. Voltage-controlled spin transport through a pair of Buckminster fullerene molecules encapsulating cobalt atoms

    NASA Astrophysics Data System (ADS)

    Saffarzadeh, Alireza; Kirczenow, George

    2013-03-01

    Carbon-based nanostructures such as fullerenes, carbon nanotubes, and graphene, are promising candidates for spintronic applications because of their weak spin-orbit coupling and hyperfine interaction which lead to long spin coherence lengths. In particular, a fullerene C60 molecule is an interesting carbon nanostructure which can be used as a molecular bridge in magnetic tunnel junctions due to its remarkable structural stability and electronic properties which make the molecule convenient for easier spin injection in magnetic nanojunctions. Here, we show that using cobalt atoms encapsulated in a pair of Buckminster fullerene molecules sandwiched between gold electrodes, density of states spin polarizations as large as 95% are found by varying the gate and/or bias voltage, due to the spin-splitting of Co 3 d orbitals. The current-voltage characteristics and strong (up to 100%) spin polarization of the current indicate that the device can be utilized for highly efficient spin injection into nonmagnetic conductors. These results open the way to voltage-controlled spin filters and magnetic sensors using molecular magnetic junctions. This work was supported by NSERC and CIFAR.

  1. 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.

  2. 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.

  3. Controlling the quantum state of a single photon emitted from a single polariton

    SciTech Connect

    Stanojevic, Jovica; Parigi, Valentina; Bimbard, Erwan; Tualle-Brouri, Rosa; Ourjoumtsev, Alexei; Grangier, Philippe

    2011-11-15

    We investigate in detail the optimal conditions for a high fidelity transfer from a single-polariton state to a single-photon state and subsequent homodyne detection of the single photon. We assume that, using various possible techniques, the single polariton has initially been stored as a spin-wave grating in a cloud of cold atoms inside a low-finesse cavity. This state is then transferred to a single-photon optical pulse using an auxiliary beam. We optimize the retrieval efficiency and determine the mode of the local oscillator that maximizes the homodyne efficiency of such a photon. We find that both efficiencies can have values close to one in a large region of experimental parameters.

  4. 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.

  5. 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.

  6. Spin Injection in Indium Arsenide

    NASA Astrophysics Data System (ADS)

    Johnson, Mark; Koo, Hyun; Han, Suk; Chang, Joonyeon

    2015-08-01

    In a two dimensional electron system (2DES), coherent spin precession of a ballistic spin polarized current, controlled by the Rashba spin orbit interaction, is a remarkable phenomenon that’s been observed only recently. Datta and Das predicted this precession would manifest as an oscillation in the source-drain conductance of the channel in a spin-injected field effect transistor (Spin FET). The indium arsenide single quantum well materials system has proven to be ideal for experimental confirmation. The 2DES carriers have high mobility, low sheet resistance, and high spin orbit interaction. Techniques for electrical injection and detection of spin polarized carriers were developed over the last two decades. Adapting the proposed Spin FET to the Johnson-Silsbee nonlocal geometry was a key to the first experimental demonstration of gate voltage controlled coherent spin precession. More recently, a new technique measured the oscillation as a function of channel length. This article gives an overview of the experimental phenomenology of the spin injection technique. We then review details of the application of the technique to InAs single quantum well (SQW) devices. The effective magnetic field associated with Rashba spin-orbit coupling is described, and a heuristic model of coherent spin precession is presented. The two successful empirical demonstrations of the Datta Das conductance oscillation are then described and discussed.

  7. 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.

  8. Phase control of the spin-triplet state in S/F/S Josephson junctions

    NASA Astrophysics Data System (ADS)

    Gingrich, Eric C.

    For decades, the proximity effect in superconductor/ferromagnetic (S/F) hybrid systems was thought to be very short-ranged, with coherence lengths on the order of a nanometer. That changed in 2003 when Bergeret et al. suggested systems involving s-wave superconductors and ferromagnets with non-collinear magnetizations could generate spin-triplet supercurrent. This was a significant prediction that radically changed the outlook for these systems, with the possibility of bringing the ferromagnetic coherence length up to ranges similar to the normal metal coherence length. With the experimental confirmation of the spin-triplet state in S/F/S Josephson junctions in 2010, the flood-gates opened into a range of interesting studies. We have performed measurements on the magnetic and superconducting properties of the multilayer Ni/[Co/Ni]n. This arrangement of ferromagnetic materials, when grown with thicknesses of 0.4 nm Ni and 0.2 nm Co, demonstrate a magnetization that lies perpendicular to the plane of the films. Because it will, in the virgin state, possess a non-collinear magnetization with ferromagnets which have magnetizations that lie within the plane, it is a convenient multilayer for the generation of spin-triplet supercurrent. Our measurements of S/F'/F/F'/S Josephson junctions, where F' is a hard ferromagnet and F is the Co/Ni multilayer, confirmed the presence of the spin-triplet state, and demonstrated the viability of the Co/Ni multilayer as a triplet generating ferromagnet. We have also performed studies on the characteristics of a number of soft ferromagnetic alloys. These alloys are important for their potential as a soft ferromagnetic switching layer for application in our triplet control devices. To that end, we have created sputtering targets for four different ferromagnetic alloys: Molybdenum-doped Permalloy, Niobium-doped Permalloy, Copper-doped Permalloy, and Palladium Iron. These studies have included: atomic concentration measurements using EDS, magnetic measurements using a commercial MPMS measurement system and GMR, and superconducting studies done by fabricating S/F'/F/F''/S Josephson junctions with F'' the soft ferromagnet of interest. Lastly, we have performed measurements to study the relative phase of two S/F'/F/F''/S Josephson junctions patterned into a Superconducting Quantum Interference Device (SQUID). The phase of the junctions is determined by the relative rotation of the magnetizations through the junction. By applying an external field to the junctions, and utilizing shape anisotropy to control the switching fields, the F'' layer can be switched in a single junction. The switch in the state can be observed by measuring the interference in the current driven through the SQUID, which responds to the relative phase of the two junctions in the loop. These measurements have yielded promising early results for the prospect of controlling the spin-triplet state.

  9. 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

  10. Control of light polarization using optically spin-injected vertical external cavity surface emitting lasers

    NASA Astrophysics Data System (ADS)

    Frougier, J.; Baili, G.; Alouini, M.; Sagnes, I.; Jaffrs, H.; Garnache, A.; Deranlot, C.; Dolfi, D.; George, J.-M.

    2013-12-01

    We fabricated and characterized an optically pumped (100)-oriented InGaAs/GaAsP multiple quantum well Vertical External Cavity Surface Emitting Laser (VECSEL). The structure is designed to allow the integration of a Metal-Tunnel-Junction ferromagnetic spin-injector for future electrical injection. We report here the control at room temperature of the electromagnetic field polarization using optical spin injection in the active medium of the VECSEL. The switching between two highly circular polarization states had been demonstrated using an M-shaped extended cavity in multi-modes lasing. This result witnesses an efficient spin-injection in the active medium of the LASER.

  11. Magneto-optical control of atomic spin mixing in dipolar spinor Bose-Einstein condensates

    SciTech Connect

    Jing, H.; Jiang, Y.; Meystre, P.

    2009-12-15

    We study the role in an external photoassociation light field in the spin mixing dynamics of a spin-one Bose condensate with long-range magnetic dipole-dipole interaction. The mean-field energy functional of the system is found to be formally identical to that of two coupled nonrigid pendulums, manifesting either constructive or destructive interferences. The interplay between photoassociation and the magnetic dipole-dipole interaction provides a novel route to the magneto-optical quantum control of atomic spin mixing in dipolar spinor condensates.

  12. Control of light polarization using optically spin-injected vertical external cavity surface emitting lasers

    SciTech Connect

    Frougier, J. Jaffrès, H.; Deranlot, C.; George, J.-M.; Baili, G.; Dolfi, D.; Alouini, M.; Sagnes, I.; Garnache, A.

    2013-12-16

    We fabricated and characterized an optically pumped (100)-oriented InGaAs/GaAsP multiple quantum well Vertical External Cavity Surface Emitting Laser (VECSEL). The structure is designed to allow the integration of a Metal-Tunnel-Junction ferromagnetic spin-injector for future electrical injection. We report here the control at room temperature of the electromagnetic field polarization using optical spin injection in the active medium of the VECSEL. The switching between two highly circular polarization states had been demonstrated using an M-shaped extended cavity in multi-modes lasing. This result witnesses an efficient spin-injection in the active medium of the LASER.

  13. Conductance and spin-filter effects of oxygen-incorporated Au, Cu, and Fe single-atom chains

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaolong; Xie, Yi-Qun; Ye, Xiang; Ke, San-Huang

    2015-01-01

    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 (<1G0) 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 0.6G0 can be attributed to a distorted chain doped with a single oxygen atom, while the 0.1G0 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 dz orbitals of adjacent Au atoms. For the Cu SACs, the conductance about 0.3G0 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 ˜0.1G0. 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.

  14. Quantum toys for quantum computing: persistent currents controlled by the spin Josephson effect.

    PubMed

    Tatara, Gen; Garcia, N

    2003-08-15

    Quantum devices and computers will need operational units in different architectural configurations for their functioning. The unit should be a simple "quantum toy," an easy to handle superposition state. Here such a novel unit of quantum mechanical flux state (or persistent current) in a conducting ring with three ferromagnetic quantum dots is presented. The state is labeled by the two directions of the persistent current, which is driven by the spin chirality of the dots, and is controlled by the spin (the spin Josephson effect). It is demonstrated that by the use of two connected rings, one can carry out unitary transformations on the input flux state by controlling one spin in one of the rings, enabling us to prepare superposition states. The flux is shown to be a quantum operation gate, and may be useful in quantum computing. PMID:12935044

  15. Generation and electric control of spin-valley-coupled circular photogalvanic current in WSe2.

    PubMed

    Yuan, Hongtao; Wang, Xinqiang; Lian, Biao; Zhang, Haijun; Fang, Xianfa; Shen, Bo; Xu, Gang; Xu, Yong; Zhang, Shou-Cheng; Hwang, Harold Y; Cui, Yi

    2014-10-01

    The valley degree of freedom in layered transition-metal dichalcogenides provides an opportunity to extend the functionalities of spintronics and valleytronics devices. The achievement of spin-coupled valley polarization induced by the non-equilibrium charge-carrier imbalance between two degenerate and inequivalent valleys has been demonstrated theoretically and by optical experiments. However, the generation of a valley and spin current with the valley polarization in transition-metal dichalcogenides remains elusive. Here we demonstrate a spin-coupled valley photocurrent, within an electric-double-layer transistor based on WSe2, whose direction and magnitude depend on the degree of circular polarization of the incident radiation and can be further modulated with an external electric field. This room-temperature generation and electric control of a valley and spin photocurrent provides a new property of electrons in transition-metal dichalcogenide systems, and thereby enables additional degrees of control for quantum-confined spintronic devices. PMID:25194947

  16. Spin filter and spin valve in ferromagnetic graphene

    SciTech Connect

    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.

  17. Electrical control of quantum-dot fine-structure splitting for high-fidelity hole spin initialization

    NASA Astrophysics Data System (ADS)

    Mar, J. D.; Baumberg, J. J.; Xu, X. L.; Irvine, A. C.; Williams, D. A.

    2016-01-01

    We demonstrate electrical control of the neutral exciton fine-structure splitting in a single InAs/GaAs self-assembled quantum dot by significantly reducing the splitting to near zero through the application of a vertical electric field in the fast electron tunneling regime. This is verified by performing high-resolution photocurrent spectroscopy of the two fine-structure split exciton eigenstates as a function of reverse bias voltage. Using the qubit initialization scheme for a quantum-dot hole spin based on rapid electric-field ionization of a spin-polarized exciton, our results suggest a practical approach towards achieving qubit initialization with near-unity fidelity in the absence of magnetic fields.

  18. Optimal control of fast and high-fidelity quantum gates with electron and nuclear spins of a nitrogen-vacancy center in diamond

    NASA Astrophysics Data System (ADS)

    Chou, Yi; Huang, Shang-Yu; Goan, Hsi-Sheng

    2015-05-01

    A negatively charged nitrogen-vacancy (NV) center in diamond has been recognized as a good solid-state qubit. A system consisting of the electronic spin of the NV center and hyperfine-coupled nitrogen and additionally nearby carbon nuclear spins can form a quantum register of several qubits for quantum information processing or as a node in a quantum repeater. Several impressive experiments on the hybrid electron and nuclear spin register have been reported, but fidelities achieved so far are not yet at or below the thresholds required for fault-tolerant quantum computation (FTQC). Using quantum optimal control theory based on the Krotov method, we show here that fast and high-fidelity single-qubit and two-qubit gates in the universal quantum gate set for FTQC, taking into account the effects of the leakage state, nearby noise qubits, and distant bath spins, can be achieved with errors less than those required by the threshold theorem of FTQC.

  19. 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.

  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.