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1

Control of single spin in Markovian environment  

E-print Network

In this article we study the control of single spin in Markovian environment. Given an initial state, we compute all the possible states to which the spin can be driven at arbitrary time, under the assumption that fast ...

Yuan, Haidong

2

Coherent, Mechanical Control of a Single Electronic Spin Sungkun Hong,,  

E-print Network

Coherent, Mechanical Control of a Single Electronic Spin Sungkun Hong,, Michael S. Grinolds coherent quantum control of a single spin driven by the motion of a mechanical resonator. The motion of a mechanical resonator is magnetically coupled to the electronic spin of a single nitrogen-vacancy center

Walsworth, Ronald L.

3

Electrical control of single hole spins in nanowire quantum dots.  

PubMed

The development of viable quantum computation devices will require the ability to preserve the coherence of quantum bits (qubits). Single electron spins in semiconductor quantum dots are a versatile platform for quantum information processing, but controlling decoherence remains a considerable challenge. Hole spins in III-V semiconductors have unique properties, such as a strong spin-orbit interaction and weak coupling to nuclear spins, and therefore, have the potential for enhanced spin control and longer coherence times. A weaker hyperfine interaction has previously been reported in self-assembled quantum dots using quantum optics techniques, but the development of hole-spin-based electronic devices in conventional III-V heterostructures has been limited by fabrication challenges. Here, we show that gate-tunable hole quantum dots can be formed in InSb nanowires and used to demonstrate Pauli spin blockade and electrical control of single hole spins. The devices are fully tunable between hole and electron quantum dots, which allows the hyperfine interaction strengths, g-factors and spin blockade anisotropies to be compared directly in the two regimes. PMID:23416794

Pribiag, V S; Nadj-Perge, S; Frolov, S M; van den Berg, J W G; van Weperen, I; Plissard, S R; Bakkers, E P A M; Kouwenhoven, L P

2013-03-01

4

Quantum control and nanoscale placement of single spins in diamond  

NASA Astrophysics Data System (ADS)

Diamond is a unique solid state platform for fundamental studies of spintronics and quantum information science that has recently enabled control, readout, and storage of quantum states at the single spin level. Nitrogen-vacancy (NV) center spins can be individually addressed and have remarkably long spin coherence times at room temperature. We show that the spin of single NV centers in both the orbital groundootnotetext G. D. Fuchs, V. V. Dobrovitski, D. M. Toyli, F. J. Heremans, and D. D. Awschalom, Science 326, 1520 (2009). and excited stateootnotetextG. D. Fuchs, V. V. Dobrovitski, D. M. Toyli, F. J. Heremans, C. D. Weis, T. Schenkel, and D.D. Awschalom, Nat. Phys. 6, 668 (2010). can be controlled on sub-nanosecond time scales using intense microwave fields. Moreover, coherent light-matter interactions enable non-destructive spin measurement and localized single spin manipulation with near-resonant light.ootnotetextB. B. Buckley, G. D. Fuchs, L. C. Bassett, and D. D. Awschalom,Science Express (DOI: 10.1126/science.1196436) An associated quantum memory is also demonstrated using the intrinsic nuclear spin of nitrogen.ootnotetextG. D. Fuchs, G. Burkard, P. Klimov, and D. D. Awschalom, in preparation. Scaling these findings toward a spin network is a key challenge - to this end we present a simple method for patterning NV center formation on 50 nm length scales.ootnotetext D. M. Toyli, C. D. Weis, G. D. Fuchs, T. Schenkel, and D. D. Awschalom,NanoLett. 10, 3168 (2010). These results represent progress toward control, coupling, and scaling of single spins for future spin and photon based quantum information processing.

Awschalom, David D.

2011-03-01

5

Control of single-spin magnetic anisotropy by exchange coupling  

NASA Astrophysics Data System (ADS)

The properties of quantum systems interacting with their environment, commonly called open quantum systems, can be affected strongly by this interaction. Although this can lead to unwanted consequences, such as causing decoherence in qubits used for quantum computation, it can also be exploited as a probe of the environment. For example, magnetic resonance imaging is based on the dependence of the spin relaxation times of protons in water molecules in a host's tissue. Here we show that the excitation energy of a single spin, which is determined by magnetocrystalline anisotropy and controls its stability and suitability for use in magnetic data-storage devices, can be modified by varying the exchange coupling of the spin to a nearby conductive electrode. Using scanning tunnelling microscopy and spectroscopy, we observe variations up to a factor of two of the spin excitation energies of individual atoms as the strength of the spin's coupling to the surrounding electronic bath changes. These observations, combined with calculations, show that exchange coupling can strongly modify the magnetic anisotropy. This system is thus one of the few open quantum systems in which the energy levels, and not just the excited-state lifetimes, can be renormalized controllably. Furthermore, we demonstrate that the magnetocrystalline anisotropy, a property normally determined by the local structure around a spin, can be tuned electronically. These effects may play a significant role in the development of spintronic devices in which an individual magnetic atom or molecule is coupled to conducting leads.

Oberg, Jenny C.; Calvo, M. Reyes; Delgado, Fernando; Moro-Lagares, María; Serrate, David; Jacob, David; Fernández-Rossier, Joaquín; Hirjibehedin, Cyrus F.

2014-01-01

6

Readout and control of a single nuclear spin with a metastable electron spin ancilla.  

PubMed

Electron and nuclear spins associated with point defects in insulators are promising systems for solid-state quantum technology. The electron spin is usually used for readout and addressing, and nuclear spins are used as exquisite quantum bits and memory systems. With these systems, single-shot readout of single nuclear spins as well as entanglement, aided by the electron spin, have been shown. Although the electron spin in this example is essential for readout, it usually limits the nuclear spin coherence, leading to a quest for defects with spin-free ground states. Here, we isolate a hitherto unidentified defect in diamond and use it at room temperature to demonstrate optical spin polarization and readout with exceptionally high contrast (up to 45%), coherent manipulation of an individual excited triplet state spin, and coherent nuclear spin manipulation using the triplet electron spin as a metastable ancilla. We demonstrate nuclear magnetic resonance and Rabi oscillations of the uncoupled nuclear spin in the spin-free electronic ground state. Our study demonstrates that nuclei coupled to single metastable electron spins are useful quantum systems with long memory times, in spite of electronic relaxation processes. PMID:23793305

Lee, Sang-Yun; Widmann, Matthias; Rendler, Torsten; Doherty, Marcus W; Babinec, Thomas M; Yang, Sen; Eyer, Moritz; Siyushev, Petr; Hausmann, Birgit J M; Loncar, Marko; Bodrog, Zoltán; Gali, Adam; Manson, Neil B; Fedder, Helmut; Wrachtrup, Jörg

2013-07-01

7

Ultrafast Coherent Control of a Single Electron Spin in a Quantum Dot  

NASA Astrophysics Data System (ADS)

Practical quantum information processing schemes require fast single-qubit operations. For spin-based qubits, this involves performing arbitrary coherent rotations of the spin state on timescales much faster than the spin coherence time. While we recently demonstrated the ability to initialize and monitor the evolution of single spins in quantum dots (QDs)ootnotetextM. H. Mikkelsen, J. Berezovsky, N. G. Stoltz, L. A. Coldren, D. D. Awschalom, Nature Physics 3, 770 (2007); J. Berezovsky, M. H. Mikkelsen, O. Gywat, N. G. Stoltz, L. A. Coldren, and D. D. Awschalom, Science 314, 1916 (2006)., here we present an all-optical scheme for ultrafast manipulation of these states through arbitrary angles. The GaAs QDs are embedded in a diode structure to allow controllable charging of the QDs and positioned within a vertical optical cavity to enhance the small single spin signal. By applying off-resonant optical pulses, we coherently rotate a single electron spin in a QD up to ? radians on picosecond timescales ootnotetextJ. Berezovsky, M. H. Mikkelsen, N. G. Stoltz, L. A. Coldren, D. D. Awschalom, Science 320, 349 (2008)..We directly observe this spin manipulation using time-resolved Kerr rotation spectroscopy at T=10K. Measurements of the spin rotation as a function of laser detuning and intensity confirm that the optical Stark effect is the operative mechanism and the results are well-described by a model including the electron-nuclear spin interaction. Using short tipping pulses, this technique enables one to perform a large number of operations within the coherence time. This ability to perform arbitrary single-qubit operations enables sequential all-optical initialization, ultrafast control and detection of a single electron spin for quantum information purposes.

Mikkelsen, Maiken H.

2009-03-01

8

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

PubMed Central

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

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

9

TRANSVERSITY SINGLE SPIN ASYMMETRIES.  

SciTech Connect

The theoretical aspects of two leading twist transversity single spin asymmetries, one arising from the Collins effect and one from the interference fragmentation functions, are reviewed. Issues of factorization, evolution and Sudakov factors for the relevant observables are discussed. These theoretical considerations pinpoint the most realistic scenarios towards measurements of transversity.

BOER,D.

2001-04-27

10

Gate control of single-electron spins: a multi-scale numerical simulation approach  

NASA Astrophysics Data System (ADS)

Among recent proposals for next-generation, non-charge-based logic is the notion that a single electron can be trapped and its spin manipulated through the application of gate voltages (Rev. Mod. Phys. 79, 1217 (2007)). In this talk we present numerical simulations of such Spin Single Electron Transistors (SSET) in support of experimental work at the University at Albany, State University of New York aimed at the practical development of post-CMOS concepts and devices. We use a multi-scale simulation strategy to self-consistently solve the Schroedinger-Poisson equations (with and without exchange-correlation effects) to obtain realistic confining and gating potentials for realistic device geometries. We discuss scaling of the equations in the various sub domains of a finite-element discretization to span the dimensions from the micron scale of the gate structures down the single-electron level. We will discuss the calculation of the gate-tuned ``g-factor" for electrons and holes (Phys. Rev. B 68, 155330 (2003)) in electro-statically- and lithographically-defined quantum dots including the Rashba and Dresselhaus spin-orbit interactions computed numerically from realistic wave functions. This work is supported through funding from the DARPA/NRI INDEX center.

Prabhakar, Sanjay; Raynolds, James

2008-03-01

11

Determinisitic Writing and Control of the Dark Exciton Spin using Short Single Optical Pulses  

E-print Network

We demonstrate that the quantum dot-confined dark exciton forms a long-lived integer spin solid state qubit which can be deterministically on-demand initiated in a pure state by one optical pulse. Moreover, we show that this qubit can be fully controlled using short optical pulses, which are several orders of magnitude shorter than the life and coherence times of the qubit. Our demonstrations do not require an externally applied magnetic field and they establish that the quantum dot-confined dark exciton forms an excellent solid state matter qubit with some advantages over the half-integer spin qubits such as the confined electron and hole, separately. Since quantum dots are semiconductor nanostructures that allow integration of electronic and photonic components, the dark exciton may have important implications on implementations of quantum technologies consisting of semiconductor qubits.

I. Schwartz; E. R. Schmidgall; L. Gantz; D. Cogan; E. Bordo; D. Gershoni

2014-08-13

12

Single-atom spin qubits in silicon  

NASA Astrophysics Data System (ADS)

Spin qubits in silicon are excellent candidates for scalable quantum information processing (QIP) due to their long coherence times and the enormous investment in silicon MOS technology. Here I discuss qubits based upon single phosphorus (P) dopant atoms in Si [1]. Projective readout of such qubits had proved challenging until single-shot measurement of a single donor electron spin was demonstrated [2] using a silicon single electron transistor (Si-SET) and the process of spin-to-charge conversion. The measurement gave readout fidelities 90% and spin lifetimes T1e 6 s [2], opening the path to demonstration of electron and nuclear spin qubits in silicon. Integrating an on-chip microwave transmission line enabled single-electron spin resonance (ESR) of the P donor electron. We used this to demonstrate Rabi oscillations of the electron spin qubit, while a Hahn echo sequence revealed electron spin coherence times T2e 0.2 ms [3]. This time is expected to become much longer in isotopically enriched ^28Si devices. We also achieved single-shot readout of the ^31P nuclear spin (with fidelity 99.6%) by monitoring the two hyperfine-split ESR lines of the P donor system. By applying (local) NMR pulses we demonstrated coherent control of the nuclear spin qubit, giving a coherence time T2n 60 ms. [4pt] [1] B.E. Kane, Nature 393, 133 (1998). [2] A. Morello et al., Nature 467, 687 (2010). [3] J.J. Pla et al., Nature 489, 541 (2012).

Dzurak, Andrew

2013-03-01

13

Decoherence dynamics of a single spin versus spin ensemble  

SciTech Connect

We study decoherence of central spins by a spin bath, focusing on the difference between measurement of a single central spin and measurement of a large number of central spins (as found in typical spin-resonance experiments). For a dilute spin bath, the single spin demonstrates Gaussian free-induction decay, in contrast to exponential decay characteristic of spin ensembles. A strong difference between a single spin and a spin ensemble also exists for the Rabi oscillation decay: for a repeated Rabi oscillation experiment, suppression of decoherence happens for a single spin while acceleration takes place for a spin ensemble. The mathematical origin of such behavior is similar to quantum Zeno/anti-Zeno effects.

Dobrovitski, V. V.; Feiguin, A. E.; Awschalom, D. D.; Hanson, R.

2008-06-26

14

Electrically driven nuclear spin resonance in single-molecule magnets.  

PubMed

Recent advances in addressing isolated nuclear spins have opened up a path toward using nuclear-spin-based quantum bits. Local magnetic fields are normally used to coherently manipulate the state of the nuclear spin; however, electrical manipulation would allow for fast switching and spatially confined spin control. Here, we propose and demonstrate coherent single nuclear spin manipulation using electric fields only. Because there is no direct coupling between the spin and the electric field, we make use of the hyperfine Stark effect as a magnetic field transducer at the atomic level. This quantum-mechanical process is present in all nuclear spin systems, such as phosphorus or bismuth atoms in silicon, and offers a general route toward the electrical control of nuclear-spin-based devices. PMID:24904159

Thiele, Stefan; Balestro, Franck; Ballou, Rafik; Klyatskaya, Svetlana; Ruben, Mario; Wernsdorfer, Wolfgang

2014-06-01

15

Electrical control of quantum dot spin qubits  

NASA Astrophysics Data System (ADS)

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

Laird, Edward Alexander

16

Single-shot readout of an electron spin in silicon  

E-print Network

The size of silicon transistors used in microelectronic devices is shrinking to the level where quantum effects become important. While this presents a significant challenge for the further scaling of microprocessors, it provides the potential for radical innovations in the form of spin-based quantum computers and spintronic devices. An electron spin in Si can represent a well-isolated quantum bit with long coherence times because of the weak spin-orbit coupling and the possibility to eliminate nuclear spins from the bulk crystal. However, the control of single electrons in Si has proved challenging, and has so far hindered the observation and manipulation of a single spin. Here we report the first demonstration of single-shot, time-resolved readout of an electron spin in Si. This has been performed in a device consisting of implanted phosphorus donors coupled to a metal-oxide-semiconductor single-electron transistor - compatible with current microelectronic technology. We observed a spin lifetime approaching 1 second at magnetic fields below 2 T, and achieved spin readout fidelity better than 90%. High-fidelity single-shot spin readout in Si opens the path to the development of a new generation of quantum computing and spintronic devices, built using the most important material in the semiconductor industry.

Andrea Morello; Jarryd J. Pla; Floris A. Zwanenburg; Kok W. Chan; Hans Huebl; Mikko Mottonen; Christopher D. Nugroho; Changyi Yang; Jessica A. van Donkelaar; Andrew D. C. Alves; David N. Jamieson; Christopher C. Escott; Lloyd C. L. Hollenberg; Robert G. Clark; Andrew S. Dzurak

2010-03-13

17

Single-shot readout of a single nuclear spin.  

PubMed

Projective measurement of single electron and nuclear spins has evolved from a gedanken experiment to a problem relevant for applications in atomic-scale technologies like quantum computing. Although several approaches allow for detection of a spin of single atoms and molecules, multiple repetitions of the experiment that are usually required for achieving a detectable signal obscure the intrinsic quantum nature of the spin's behavior. We demonstrated single-shot, projective measurement of a single nuclear spin in diamond using a quantum nondemolition measurement scheme, which allows real-time observation of an individual nuclear spin's state in a room-temperature solid. Such an ideal measurement is crucial for realization of, for example, quantum error correction protocols in a quantum register. PMID:20595582

Neumann, Philipp; Beck, Johannes; Steiner, Matthias; Rempp, Florian; Fedder, Helmut; Hemmer, Philip R; Wrachtrup, Jörg; Jelezko, Fedor

2010-07-30

18

Spin effects in single-electron transistors  

E-print Network

Basic electron transport phenomena observed in single-electron transistors (SETs) are introduced, such as Coulomb-blockade diamonds, inelastic cotunneling thresholds, the spin-1/2 Kondo effect, and Fano interference. With ...

Granger, Ghislain

2005-01-01

19

Single Spin Measurement Using Cellular Automata Techniques  

SciTech Connect

We analyze a conceptual approach to single-spin measurement. The method uses techniques from the theory of quantum cellular automata to correlate a large number of ancillary spins to the one to be measured. It has the distinct advantage of being efficient: under ideal conditions, it requires the application of only O({sup 3}{radical}(N)) steps (each requiring a constant number of rf pulses) to create a system of N correlated spins. Numerical simulations suggest that it is also, to a certain extent, robust against pulse errors, and imperfect initial polarization of the ancilla spin system.

Perez-Delgado, Carlos A. [Institute for Quantum Computing, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Mosca, Michele [Institute for Quantum Computing, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Perimeter Institute for Theoretical Physics, Waterloo, ON N2J 2W9 (Canada); Cappellaro, Paola; Cory, David G. [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2006-09-08

20

Resolution of Single Spin Flips of a Single Proton  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

21

Single spin stochastic optical reconstruction microscopy  

E-print Network

We experimentally demonstrate precision addressing of single quantum emitters by combined optical microscopy and spin resonance techniques. To this end we utilize 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 sca...

Pfender, Matthias; Waldherr, Gerald; Wrachtrup, Jörg

2014-01-01

22

Single-shot readout of an electron spin in silicon  

E-print Network

The size of silicon transistors used in microelectronic devices is shrinking to the level where quantum effects become important. While this presents a significant challenge for the further scaling of microprocessors, it provides the potential for radical innovations in the form of spin-based quantum computers and spintronic devices. An electron spin in Si can represent a well-isolated quantum bit with long coherence times because of the weak spin-orbit coupling and the possibility to eliminate nuclear spins from the bulk crystal. However, the control of single electrons in Si has proved challenging, and has so far hindered the observation and manipulation of a single spin. Here we report the first demonstration of single-shot, time-resolved readout of an electron spin in Si. This has been performed in a device consisting of implanted phosphorus donors coupled to a metal-oxide-semiconductor single-electron transistor - compatible with current microelectronic technology. We observed a spin lifetime approaching...

Morello, Andrea; Zwanenburg, Floris A; Chan, Kok W; Huebl, Hans; Mottonen, Mikko; Nugroho, Christopher D; Yang, Changyi; van Donkelaar, Jessica A; Alves, Andrew D C; Jamieson, David N; Escott, Christopher C; Hollenberg, Lloyd C L; Clark, Robert G; Dzurak, Andrew S

2010-01-01

23

Spin-polarized current induced in a single ferromagnetic strip due to inhomogeneous spin injection  

E-print Network

Spin-polarized current induced in a single ferromagnetic strip due to inhomogeneous spin injection that the inhomogeneous spin accumulation in a nonmagnetic layer induces the spin-polarized current flowing in a detector, the induced spin-polarized current causes the spin-valve-like signal in the Ni-Fe wire without any boundary

Otani, Yoshichika

24

Single-Spin Asymmetries and Transversity  

NASA Astrophysics Data System (ADS)

A pedagogical introduction to single-spin asymmetries (SSA's) and transversity is presented. Discussion in some detail is made of certain aspects of SSA's in lepton-nucleon and in hadron-hadron scattering and the role of pQCD and evolution in the context of transversity.

Ratcliffe, Philip G.

2003-07-01

25

Single-Spin Asymmetries and Transversity  

E-print Network

A pedagogical introduction to single-spin asymmetries (SSA's) and transversity is presented. Discussion in some detail is made of certain aspects of (SSA's) in lepton-nucleon and in hadron-hadron scattering and the role of pQCD and evolution in the context of transversity.

Ratcliffe, P G

2002-01-01

26

Neutron single target spin asymmetries in SIDIS  

SciTech Connect

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.

Evaristo Cisbani

2010-04-01

27

Single-spin stochastic optical reconstruction microscopy.  

PubMed

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

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

2014-10-14

28

Single spin stochastic optical reconstruction microscopy  

E-print Network

We experimentally demonstrate precision addressing of single quantum emitters by combined optical microscopy and spin resonance techniques. To this end we utilize 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.

Matthias Pfender; Nabeel Aslam; Gerald Waldherr; Jörg Wrachtrup

2014-04-05

29

Spin-current autocorrelations from single pure-state propagation.  

PubMed

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. PMID:24724642

Steinigeweg, Robin; Gemmer, Jochen; Brenig, Wolfram

2014-03-28

30

Target Single Spin Asymmetry in DVCS  

NASA Astrophysics Data System (ADS)

The target single spin asymmetry in the reaction ep-> ep? is directly proportional to the imaginary part of the Deeply Virtual Compton Scattering (DVCS) amplitude and gives access to a combination of the Generalized Parton Distributions (GPDs) H˜, H, and E. We present the preliminary single spin asymmetry studies from the eg1-dvcs experiment conducted in Hall B of Jefferson Lab using the Continuous Electron Beam Accelerator Facility's (CEBAF) 6 GeV electron beam, a polarized solid-state (^14NH3) target, and the CEBAF Large Acceptance Spectrometer (CLAS) equipped with an additionally built Inner Calorimeter (IC). The high statistics collected allow for detailed studies of the Q(^2), x(B) and t dependences of the DVCS amplitude over a wide range of kinematics.

Seder, Erin

2011-10-01

31

Collins Mechanism Contributions to Single Spin Asymmetry  

SciTech Connect

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

Yuan,F.

2009-05-25

32

Collins Mechanism Contributions to Single Spin Asymmetry  

SciTech Connect

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

Yuan,F.

2009-05-26

33

Collins Mechanism Contributions to Single Spin Asymmetry  

SciTech Connect

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

Yuan, Feng

2009-09-11

34

Gate control of single-electron spins through Berry Phase in a realistic asymmetric confining potentials in III-V semiconductor Quantum Dots  

NASA Astrophysics Data System (ADS)

Among recent proposals for next-generation, non-charge-based logic is the notion that a single electron can be trapped and its spin can be manipulated through the application of gate voltages (Rev. Mod. Phys.79, 1217 (2007)). In this talk we present numerical simulations of Berry Phase of electron spins in single electron devices for realistic asymmetric confining potentials in support of experimental work at the University at Albany, State University of New York aimed at the practical development of post-CMOS concepts and devices. We solve the Schr"odinger equation including spin-orbit effects using a numerical finite-element based technique. We will discuss the calculation of Berry Phase for electrons (Phys. Rev. B 73, 125330 (2006)) in electrostatically defined quantum dots including the Rashba and Dresselhaus spin-orbit interactions computed numerically from realistic asymmetric confining potentials. The new simulation results open the possibility of spin manipulation through the gate induced Berry phase. This work is supported through funding from the DARPA/NRI INDEX center.

Prabhakar, Sanjay; Raynolds, James

2009-03-01

35

Quantum logic readout and cooling of a single dark electron spin  

NASA Astrophysics Data System (ADS)

We study a single dark N2 electron spin defect in diamond, which is magnetically coupled to a nearby nitrogen-vacancy (NV) center. We perform pulsed electron spin resonance on this single spin by mapping its state to the NV center spin and optically reading out the latter. Moreover, we show that the NV center's spin polarization can be transferred to the electron spin by combined two decoupling control-NOT gates. These two results allow us to extend the NV center's two key properties—optical spin polarization and detection—to any electron spin in its vicinity. This enables dark electron spins to be used as local quantum registers and engineerable memories.

Shi, Fazhan; Zhang, Qi; Naydenov, Boris; Jelezko, Fedor; Du, Jiangfeng; Reinhard, Friedemann; Wrachtrup, Jörg

2013-05-01

36

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

37

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

E-print Network

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.

Jie Ren; Jonas Fransson; Jian-Xin Zhu

2013-10-15

38

Ultrafast optical control of individual quantum dot spin qubits.  

PubMed

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. PMID:24006335

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

2013-09-01

39

Single transverse spin asymmetry of forward neutrons  

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

40

Theoretical Study of Interaction between Photons and Single Spins  

NASA Astrophysics Data System (ADS)

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.)

Chen, Ting

41

Spinning solar sail orbit steering via spin rate control  

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

42

Voltage tunability of single spin-states in a quantum dot  

E-print Network

Single spins in the solid-state offer a unique opportunity to store and manipulate quantum information, and to perform quantum-enhanced sensing of local fields and charges. Optical control of these systems using techniques developed in atomic physics has yet to exploit all the advantages of the solid-state. We demonstrate voltage tunability of the spin energy levels in a single quantum dot by modifying how spins sense magnetic field. We find the in-plane g-factor varies discontinuously for electrons, as more holes are loaded onto the dot. In contrast, the in-plane hole g-factor varies continuously. The device can change the sign of the in-plane g-factor of a single hole, at which point an avoided crossing is observed in the two spin eigenstates. This is exactly what is required for universal control of a single spin with a single electrical gate.

Anthony J. Bennett; Matthew A. Pooley; Yameng Cao; Niklas Sköld; Ian Farrer; David A. Ritchie; Andrew J. Shields

2013-02-27

43

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

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

44

Single Spin Asymmetry in Charmonium Production  

E-print Network

We present estimates of Single Spin Asymmetry (SSA) in the electroproduction of $J/\\psi$ taking into account the transverse momentum dependent (TMD) evolution of the gluon Sivers function and using Color Evaporation Model of charmonium production. We estimate SSA for JLab, HERMES, COMPASS and eRHIC energies using recent parameters for the quark Sivers functions which are fitted using an evolution kernel in which the perturbative part is resummed up to next-to-leading logarithms (NLL) accuracy. We find that these SSAs are much smaller as compared to our first estimates obtained using DGLAP evolution but are comparable to our estimates obtained using TMD evolution where we had used approximate analytical solution of the TMD evolution equation for the purpose.

Godbole, Rohini M; Misra, Anuradha; Rawoot, Vaibhav S

2014-01-01

45

Controlling the quantum dynamics of a mesoscopic spin bath in diamond  

E-print Network

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.

G. de Lange; T. van der Sar; M. S. Blok; Z. H. Wang; V. V. Dobrovitski; R. Hanson

2011-04-24

46

Spin-dependent quantum interference within a single magnetic nanostructure.  

PubMed

Quantum interference is a coherent quantum phenomenon that takes place in confined geometries. Using spin-polarized scanning tunneling microscopy, we found that quantum interference of electrons causes spatial modulation of spin polarization within a single magnetic nanostructure. We observed changes in both the sign and magnitude of the spin polarization on a subnanometer scale. A comparison of our experimental results with ab initio calculations shows that at a given energy, the modulation of the spin polarization can be ascribed to the difference between the spatially modulated local density of states of the majority spin and the nonmodulated minority spin contribution. PMID:20150496

Oka, H; Ignatiev, P A; Wedekind, S; Rodary, G; Niebergall, L; Stepanyuk, V S; Sander, D; Kirschner, J

2010-02-12

47

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

NASA Astrophysics Data System (ADS)

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.[4pt] Reference:[0pt] ``Electronic read-out of a single nuclear spin using a molecular spin transistor,'' R. Vincent, S. Klyatskaya, M. Ruben, W. Wernsdorfer, F. Balestro, Nature, Vol. 488, p.357, (2012).

Balestro, Franck

2013-03-01

48

Optically Driven Rabi Oscillations and Adiabatic Passage of Single Electron Spins in Diamond  

NASA Astrophysics Data System (ADS)

Rabi oscillations and adiabatic passage of single electron spins in a diamond nitrogen vacancy center are demonstrated with two Raman-resonant optical pulses that are detuned from the respective dipole optical transitions. We show that the optical spin control is nuclear-spin selective and can be robust against rapid decoherence, including radiative decay and spectral diffusion, of the underlying optical transitions. A direct comparison between the Rabi oscillation and the adiabatic passage, along with a detailed theoretical analysis, provides significant physical insights into the connections and differences between these coherent spin processes and also elucidates the role of spectral diffusion in these processes. The optically driven coherent spin processes enable the use of nitrogen vacancy excited states to mediate coherent spin-phonon coupling, opening the door to combining optical control of both spin and mechanical degrees of freedom.

Golter, D. Andrew; Wang, Hailin

2014-03-01

49

Robust manipulation of electron spin coherence in an ensemble of singly charged quantum dots  

NASA Astrophysics Data System (ADS)

Using the recently reported mode-locking effect [A. Greilich , Science 313, 341 (2006)], we demonstrate a highly robust control of electron spin coherence in an ensemble of (In,Ga)As quantum dots during the single spin coherence time. The spin precession in a transverse magnetic field can be fully controlled up to 25K by the parameters of the exciting pulsed laser protocol such as the pulse train sequence, leading to adjustable quantum beat bursts in Faraday rotation. Flipping of the electron spin precession phase was demonstrated by inverting the polarization within a pulse doublet sequence.

Greilich, A.; Wiemann, M.; Hernandez, F. G. G.; Yakovlev, D. R.; Yugova, I. A.; Bayer, M.; Shabaev, A.; Efros, Al. L.; Reuter, D.; Wieck, A. D.

2007-06-01

50

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

51

Ensemble spin coherence of singly charged InGaAs quantum dots  

NASA Astrophysics Data System (ADS)

This Chapter reviews experimental and theoretical studies of electron spin coherence in singly-charged (In,Ga)As quantum dots. Ultrafast optical technique, the pump-probe Faraday rotation, is used for generation and control of the spin coherence. Despite the ensemble inhomogeneity the electron spin coherence time T2 is measured in the mode-locking regime of synchronization of the electron spin precession about external magnetic field with the periodic laser excitation. This synchronization effect is enhanced and stabilized by electron-nuclear hyperfine interaction allowing frequency focusing of the inhomogeneous electron ensemble into the single precession mode. Ultrafast optical spin rotation of resident electrons in quantum dots to any point on the Bloch sphere is demonstrated and all-optical spin echo for these electrons is realized.

Greilich, Alex; Yakovlev, Dmitri R.; Bayer, Manfred

52

Technical Notes Single-Sensor Identification of Spinning  

E-print Network

Technical Notes Single-Sensor Identification of Spinning Mode Noise from Aircraft Engine Xun Huang of aircraft. The development of high bypass ratio turbofan aircraft engines makes spinning mode noise the attention of communities that live near airports to noise pollution. To address this environmental

Huang, Xun

53

OSP Quantum Mechanics: Single Measurments of Spin States Worksheet  

NSDL National Science Digital Library

This set of tutorial worksheets, based on the OSP Quantum Mechanics Simulations, help students explore the measurement of quantum spins. The tutorial starts with an introduction of the physics of spins, and then presents the results of a single measurement on pure, mixed, and superposition states.

Belloni, Mario; Christian, Wolfgang

2010-01-11

54

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

PubMed

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 ?=1/2?, 2/3?. In the linear regime, large thermopower can be obtained by modifying V(g) and the angles (?). These results are useful in fabricating and advantaging SMM devices based on spin caloritronics. PMID:24549224

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

2014-01-01

55

Coherent control of dipolar coupled spins in large Hilbert spaces  

E-print Network

Controlling the dynamics of a dipolar-coupled spin system is critical to the development of solid-state spin-based quantum information processors. Such control remains challenging, as every spin is coupled to a large number ...

Sinha, Suddhasattwa

2006-01-01

56

Radio Frequency Scanning Tunneling Spectroscopy for Single-Molecule Spin Resonance  

NASA Astrophysics Data System (ADS)

We probe nuclear and electron spins in a single molecule even beyond the electromagnetic dipole selection rules, at readily accessible magnetic fields (few mT) and temperatures (5 K) by resonant radio-frequency current from a scanning tunneling microscope. We achieve subnanometer spatial resolution combined with single-spin sensitivity, representing a 10 orders of magnitude improvement compared to existing magnetic resonance techniques. We demonstrate the successful resonant spectroscopy of the complete manifold of nuclear and electronic magnetic transitions of up to ?Iz=±3 and ?Jz=±12 of single quantum spins in a single molecule. Our method of resonant radio-frequency scanning tunneling spectroscopy offers, atom-by-atom, unprecedented analytical power and spin control with an impact on diverse fields of nanoscience and nanotechnology.

Müllegger, Stefan; Tebi, Stefano; Das, Amal K.; Schöfberger, Wolfgang; Faschinger, Felix; Koch, Reinhold

2014-09-01

57

Radio frequency scanning tunneling spectroscopy for single-molecule spin resonance.  

PubMed

We probe nuclear and electron spins in a single molecule even beyond the electromagnetic dipole selection rules, at readily accessible magnetic fields (few mT) and temperatures (5 K) by resonant radio-frequency current from a scanning tunneling microscope. We achieve subnanometer spatial resolution combined with single-spin sensitivity, representing a 10 orders of magnitude improvement compared to existing magnetic resonance techniques. We demonstrate the successful resonant spectroscopy of the complete manifold of nuclear and electronic magnetic transitions of up to ?I_{z}=±3 and ?J_{z}=±12 of single quantum spins in a single molecule. Our method of resonant radio-frequency scanning tunneling spectroscopy offers, atom-by-atom, unprecedented analytical power and spin control with an impact on diverse fields of nanoscience and nanotechnology. PMID:25302884

Müllegger, Stefan; Tebi, Stefano; Das, Amal K; Schöfberger, Wolfgang; Faschinger, Felix; Koch, Reinhold

2014-09-26

58

Universal enhancement of the optical readout fidelity of single electron spins at nitrogen-vacancy centers in diamond  

NASA Astrophysics Data System (ADS)

Precise readout of spin states is crucial for any approach toward physical realization of a spin-based quantum computer and for magnetometry with single spins. Here, we report a method to strongly improve the optical readout fidelity of electron spin states associated with single nitrogen-vacancy (NV) centers in diamond. The signal-to-noise ratio is enhanced significantly by performing conditional flip-flop processes between the electron spin and the nuclear spin of the NV center’s nitrogen atom. The enhanced readout procedure is triggered by a short preparatory pulse sequence. As the nitrogen nuclear spin is intrinsically present in the system, this method is universally applicable to any nitrogen-vacancy center. Besides the readout method, our studies included coherent control over a single nitrogen nuclear spin for the first time.

Steiner, M.; Neumann, P.; Beck, J.; Jelezko, F.; Wrachtrup, J.

2010-01-01

59

Nuclear magnetic resonance spectroscopy with single spin sensitivity  

NASA Astrophysics Data System (ADS)

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 29Si 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.

Müller, 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.

2014-08-01

60

One dimensional electron spin imaging for single spin detection and manipulation using a gradient field  

E-print Network

magnetic field gradients. These fabricated devices are used to demonstrate this subwavelength imaging technique by imaging single electron spins of the nitrogen-vacancy (NV) defect in diamond. In this demonstration, multiple NV defects, unresolved in a...

Shin, Chang-Seok

2009-05-15

61

Creation and Control of Spin Current in Solids  

Microsoft Academic Search

Research on the flow of spin, i.e., spin current, has been attracting much attention along with the recent developments in spintronics research. Spin current is a fundamental concept in the transformation and control of various physical signals related to spin. Understanding spin current means the clarification of the mechanisms underlying the transformation and control of various physical signals, which is

Koki Takanashi

2010-01-01

62

Quantum entanglement and spin control in silicon nanocrystal.  

PubMed

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 (29)Si nanocrystal. Entangled quantum states of channeled proton trajectories are mapped in transverse and angular phase space of (29)Si <100> 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 (29)Si. 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

Berec, Vesna

2012-01-01

63

Quantum entanglement and spin control in silicon nanocrystal  

E-print Network

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.

Vesna Berec

2012-10-16

64

Coherent properties of single rare-earth spin qubits  

E-print Network

Rare-earth-doped crystals are excellent hardware for quantum storage of optical information. 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 Ce$^{3+}$ ion in a YAG crystal. Under dynamic decoupling, spin coherence lifetime reaches $T_2$=2 ms and is almost limited by the measured spin-lattice relaxation time $T_1$=3.8 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.

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

2014-05-20

65

Electric control of the spin Hall effect by intervalley transitions.  

PubMed

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

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

2014-10-01

66

Electric control of the spin Hall effect by intervalley transitions  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

67

Cryogenic single-chip electron spin resonance detector  

NASA Astrophysics Data System (ADS)

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.

Gualco, Gabriele; Anders, Jens; Sienkiewicz, Andrzej; Alberti, Stefano; Forró, László; Boero, Giovanni

2014-10-01

68

Colour Modification of Factorisation in Single-Spin Asymmetries  

E-print Network

We discuss the way in which factorisation is partially maintained but nevertheless modified by process-dependent colour factors in hadronic single-spin asymmetries. We also examine QCD evolution of the twist-three gluonic-pole strength defining an effective T-odd Sivers function in the large-x limit, where evolution of the T-even transverse-spin DIS structure function g2 is known to be multiplicative.

Ratcliffe, Philip G

2009-01-01

69

Nanomagnetism: Spin doctors play with single electrons  

NASA Astrophysics Data System (ADS)

It is now possible to prepare a semiconductor quantum dot that contains a single magnetic atom, and then add just one extra electron or 'hole' to it, opening up the possibility of a new era in spintronics.

Erwin, Steven C.

2006-11-01

70

Local quantum control of Heisenberg spin chains  

SciTech Connect

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.

Heule, Rahel; Bruder, C.; Stojanovic, Vladimir M. [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Burgarth, Daniel [Institute for Mathematical Sciences, Imperial College London SW7 2PG (United Kingdom); QOLS, The Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW (United Kingdom)

2010-11-15

71

Single electron-spin memory with a semiconductor quantum dot  

E-print Network

We show storage of the circular polarisation of an optical field, transferring it to the spin-state of an individual electron confined in a single semiconductor quantum dot. The state is subsequently readout through the electronically-triggered emission of a single photon. The emitted photon shares the same polarisation as the initial pulse but has a different energy, making the transfer of quantum information between different physical systems possible. With an applied magnetic field of 2 Tesla, spin memory is preserved for at least 1000 times more than the exciton's radiative lifetime.

Robert J. Young; Samuel J. Dewhurst; R. Mark Stevenson; Paola Atkinson; Anthony J. Bennett; Martin B. Ward; Ken Cooper; David A. Ritchie; Andrew J. Shields

2007-06-14

72

Factorisation in Higher-Twist Single-Spin Amplitudes  

E-print Network

We examine the twist-three amplitudes which can give rise to single-spin asymmetries in hadron-hadron scattering. As already known, the requirement of an imaginary part leads to consideration of twist-three contributions related to transverse spin in deep-inelastic scattering. In particular, when an external line becomes soft in contributions arising from three-parton correlators, the imaginary part of an internal propagator can be exposed. Here the factorisation properties of such amplitudes are high-lighted and simplifying relations between the spin-dependent and spin-averaged cross-sections are made evident and a series of selection rules formulated. As a result, the experimental behaviour of the asymmetries, as functions of x_F, can be naturally explained.

Ratcliffe, P G

1999-01-01

73

Single-Spin Asymmetries and Transversity in QCD  

SciTech Connect

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

Brodsky, S.J.; /SLAC

2005-12-14

74

Attitude control of a spinning rocket via thrust vectoring  

SciTech Connect

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.

White, J.E.

1990-12-19

75

SSICM (Spin Stabilized Impulsively Controlled Missile) guidance and control concept  

NASA Astrophysics Data System (ADS)

The guidance scheme utilizing wide beam width semiactive RF sensors, a precision roll attitude reference, and a controlled grade pitch, yaw and roll rate gyros to deliver high quality homing guidance information to a spin stabilized controlled missile is presented. A filtering system is utilized to eliminate errors caused by body roll signals generated due to the spin of the missiles. The nutational motion is used to calibrate the sensors. Impulsive maneuvers are utilized to intercept incoming ballistic targets.

Howell, W. M.

1985-09-01

76

Matrix Formalism for Spin Dynamics Near a Single Depolarization Resonance  

SciTech Connect

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.

Chao, Alexander W.; /SLAC

2005-10-26

77

Azimuthal and Single Spin Asymmetries in Hard Scattering Processes  

E-print Network

In this article we review the present understanding of azimuthal and single spin asymmetries for inclusive and semi-inclusive particle production in unpolarized and polarized hadronic collisions at high energy and moderately large transverse momentum. After summarizing the experimental information available, we discuss and compare the main theoretical approaches formulated in the framework of perturbative QCD. We then present in some detail a generalization of the parton model with inclusion of spin and intrinsic transverse momentum effects. In this context, we extensively discuss the phenomenology of azimuthal and single spin asymmetries for several processes in different kinematical configurations. A comparison with the predictions of other approaches, when available, is also given. We finally emphasize some relevant open points and challenges for future theoretical and experimental investigation.

U. D'Alesio; F. Murgia

2007-12-28

78

Dominant Contribution in Pion Production Single-Spin Asymmetries  

E-print Network

Working with a completely collinear twist-3 factorized cross-section formula, we identify two largely dominant partonic sub-processes, which contribute to the single-spin asymmetries in semi-inclusive pion production, in the region of large pT and medium-large xF.

Ratcliffe, Philip G

2008-01-01

79

Quantum Information Atomic Spins, Stokes Vectors for Light and Canonical Variables Light-Atom Interactions Single Atom Spin Squeezing Outlook Spin Squeezing of a Room Temperature Atomic Ensemble  

E-print Network

Quantum Information Atomic Spins, Stokes Vectors for Light and Canonical Variables Light-Atom Interactions Single Atom Spin Squeezing Outlook Spin Squeezing of a Room Temperature Atomic Ensemble Kasper University of Copenhagen Denmark April 2008 #12;Quantum Information Atomic Spins, Stokes Vectors for Light

Budker, Dmitry

80

Using nanoscale transistors to measure single donor spins in semiconductors  

SciTech Connect

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.

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

2008-12-01

81

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

NASA Astrophysics Data System (ADS)

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

Mayhall, Nicholas J.; Head-Gordon, Martin

2014-10-01

82

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

PubMed

We highlight a simple strategy for computing the magnetic coupling constants, J, for a complex containing two multiradical centers. On the assumption that the system follows Heisenberg Hamiltonian physics, J is obtained from a spin-flip electronic structure calculation where only a single electron is excited (and spin-flipped), from the single reference with maximum S?z, M, to the M - 1 manifold, regardless of the number of unpaired electrons, 2M, on the radical centers. In an active space picture involving 2M orbitals, only one ? electron is required, together with only one ? hole. While this observation is extremely simple, the reduction in the number of essential configurations from exponential in M to only linear provides dramatic computational benefits. This (M, M - 1) strategy for evaluating J is an unambiguous, spin-pure, wave function theory counterpart of the various projected broken symmetry density functional theory schemes, and likewise gives explicit energies for each possible spin-state that enable evaluation of properties. The approach is illustrated on five complexes with varying numbers of unpaired electrons, for which one spin-flip calculations are used to compute J. Some implications for further development of spin-flip methods are discussed. PMID:25296788

Mayhall, Nicholas J; Head-Gordon, Martin

2014-10-01

83

Spin quantum jumps in a singly charged quantum dot  

NASA Astrophysics Data System (ADS)

We model the population and coherence dynamics of a singly charged quantum dot driven by a constant optical field. Using a separation of time scales we predict the occurrence of quantum jumps in the spin state of the excess electron or hole. Our analysis extends the description of intermittent fluorescence from a three-level to a four-level description; the former is common in atomic systems, the later occurs in many solid-state systems. The statistics of the quantum jumps as function of the intensity of the driving field provide detailed information on physical processes that limit the ground-state coherence of these systems and their use as a solid-state quantum bit. In particular it enables a discrimination of coherent spin coupling, induced by the nuclear magnetic field, from incoherent spin flips; the coherent coupling can gradually be suppressed by increasing the pump intensity due to the quantum Zeno effect.

van Exter, M. P.; Gudat, J.; Nienhuis, G.; Bouwmeester, D.

2009-08-01

84

Strong driving of a single spin using arbitrarily polarized fields  

NASA Astrophysics Data System (ADS)

The strong-driving regime occurs when a quantum two-level system is driven with an external field whose amplitude is greater than or equal to the energy splitting between the system's states and is typically identified with the breaking of the rotating wave approximation (RWA). We report an experimental study in which the spin of a single nitrogen-vacancy (NV) center in diamond is strongly driven with microwave fields of arbitrary polarization. We measure the NV center spin dynamics beyond the RWA and characterize the limitations of this technique for generating high-fidelity quantum gates. Using circularly polarized microwave fields, the NV spin can be harmonically driven in its rotating frame regardless of the field amplitude, thus allowing rotations around arbitrary axes. Our approach can effectively remove the RWA limit in quantum-sensing schemes and assist in increasing the number of operations in QIP protocols.

London, P.; Balasubramanian, P.; Naydenov, B.; McGuinness, L. P.; Jelezko, F.

2014-07-01

85

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

NASA Astrophysics Data System (ADS)

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 ?m 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 ??/?||?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.

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

2014-08-01

86

Controlling spin relaxation in hexagonal BN-encapsulated graphene with a transverse electric field.  

PubMed

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 ?m 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 ?(?)/?(||) ? 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. PMID:25192116

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

2014-08-22

87

Electrical control of spin in topological insulators  

NASA Astrophysics Data System (ADS)

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).

Chang, Kai

2012-02-01

88

Standing spin waves as a basis for the control of terahertz spin dynamics: time dependent density functional theory study.  

PubMed

We report on the linear response density functional study of the magnetization dynamics in Co(100) film driven by a nonuniform magnetic field. At resonant frequencies in the terahertz range, the magnetic field excites standing spin waves of the system and the induced magnetization penetrates the whole volume of the film. The pattern of magnetization precession is strongly influenced by the spin-flip excitations of single electrons which lead to the Landau damping of the spin-wave modes. Our results pave the way for the precise control of terahertz magnetization dynamics in itinerant magnets. PMID:20868192

Buczek, Pawe?; Ernst, Arthur; Sandratskii, Leonid M

2010-08-27

89

Photoelectron spin-polarization control in the topological insulator Bi2Se3.  

PubMed

We study the manipulation of the spin polarization of photoemitted electrons in Bi2Se3 by spin- and angle-resolved photoemission spectroscopy. General rules are established that enable controlling the photoelectron spin-polarization. We demonstrate the ±?100% reversal of a single component of the measured spin-polarization vector upon the rotation of light polarization, as well as full three-dimensional manipulation by varying experimental configuration and photon energy. While a material-specific density-functional theory analysis is needed for the quantitative description, a minimal yet fully generalized two-atomic-layer model qualitatively accounts for the spin response based on the interplay of optical selection rules, photoelectron interference, and topological surface-state complex structure. It follows that photoelectron spin-polarization control is generically achievable in systems with a layer-dependent, entangled spin-orbital texture. PMID:24579623

Zhu, Z-H; Veenstra, C N; Zhdanovich, S; Schneider, M P; Okuda, T; Miyamoto, K; Zhu, S-Y; Namatame, H; Taniguchi, M; Haverkort, M W; Elfimov, I S; Damascelli, A

2014-02-21

90

Optical Spin Noise of a Single Hole Spin Localized in an (InGa)As Quantum Dot  

NASA Astrophysics Data System (ADS)

We advance spin noise spectroscopy to the ultimate limit of single spin detection. This technique enables the measurement of the spin dynamic of a single heavy hole localized in a flat (InGa)As quantum dot. Magnetic field and light intensity dependent studies reveal even at low magnetic fields a strong magnetic field dependence of the longitudinal heavy hole spin relaxation time with an extremely long T1 of ?180 ?s at 31 mT and 5 K. The wavelength dependence of the spin noise power discloses for finite light intensities an inhomogeneous single quantum dot spin noise spectrum which is explained by charge fluctuations in the direct neighborhood of the quantum dot. The charge fluctuations are corroborated by the distinct intensity dependence of the effective spin relaxation rate.

Dahbashi, Ramin; Hübner, Jens; Berski, Fabian; Pierz, Klaus; Oestreich, Michael

2014-04-01

91

Optical spin noise of a single hole spin localized in an (InGa)As quantum dot.  

PubMed

We advance spin noise spectroscopy to the ultimate limit of single spin detection. This technique enables the measurement of the spin dynamic of a single heavy hole localized in a flat (InGa)As quantum dot. Magnetic field and light intensity dependent studies reveal even at low magnetic fields a strong magnetic field dependence of the longitudinal heavy hole spin relaxation time with an extremely long T1 of ?180???s at 31 mT and 5 K. The wavelength dependence of the spin noise power discloses for finite light intensities an inhomogeneous single quantum dot spin noise spectrum which is explained by charge fluctuations in the direct neighborhood of the quantum dot. The charge fluctuations are corroborated by the distinct intensity dependence of the effective spin relaxation rate. PMID:24785063

Dahbashi, Ramin; Hübner, Jens; Berski, Fabian; Pierz, Klaus; Oestreich, Michael

2014-04-18

92

Single-Spin Asymmetries in Pion Electroproduction at CLAS  

NASA Astrophysics Data System (ADS)

Single-spin asymmetries (SSA) in azimuthal distributions of final state particles in deep inelastic scattering (DIS) play a crucial role in the study of the spin structure of hadrons in terms of their elementary constituents. They give access to subtle distribution and fragmentation functions, which cannot easily be accessed in other ways. The higher-twist distributions while being important for understanding the long-range quark-gluon dynamics, contribute at leading order to certain asymmetries and will be very important at low beam energies (CEBAF,HERMES) because of the phenomenon of hadron-parton duality, or ``precocious scaling''. This contribution presents latest results from Jefferson Lab's CLAS detector on beam and target SSA in pion azimuthal distributions in one particle inclusive electroproduction in the DIS regime (Q^2>1GeV^2,W>2GeV) off an unpolarized hydrogen and polarized NH3 targets. Large single-beam and single-target spin asymmetries were observed at large z (fraction of the virtual photon momentum carried by the produced pion), a domain where semi-inclusive and exclusive processes overlap in hard scattering.

Avagyan, Harut

2002-04-01

93

Optimal spin-state transition in singly occupied quantum dots network  

NASA Astrophysics Data System (ADS)

We present a general model to study the spin-state transition in a network of singly occupied lateral quantum dots. The perturbative expansion of the extended Hubbard model is used to describe the dynamics of confined electrons as an effective spin Hamiltonian in the strong correlation regime. To optimize the transition, we apply the gradient ascent pulse engineering algorithm to control the exchange couplings constrained to the manifolds evaluated by Heitler-London approximation. The method is applicable to an arbitrary number of quantum dots in any arrangement. Results of the method applied to the case of triple quantum dot are presented for linear and triangular topologies.

Yaghouti, M.; Sharifi, M. J.; Kazemi, A.

2013-01-01

94

Coherence and control of quantum registers based on electronic spin in a nuclear spin bath.  

PubMed

We consider a protocol for the control of few-qubit registers comprising one electronic spin embedded in a nuclear spin bath. We show how to isolate a few proximal nuclear spins from the rest of the bath and use them as building blocks for a potentially scalable quantum information processor. We describe how coherent control techniques based on magnetic resonance methods can be adapted to these solid-state spin systems, to provide not only efficient, high fidelity manipulation but also decoupling from the spin bath. As an example, we analyze feasible performances and practical limitations in the realistic setting of nitrogen-vacancy centers in diamond. PMID:19519089

Cappellaro, P; Jiang, L; Hodges, J S; Lukin, M D

2009-05-29

95

COMPASS Results on Transverse Single-Spin Asymmetries  

E-print Network

New results on single spin asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarised LiD target are presented. The data were taken in the years 2002, 2003 and 2004 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. Preliminary results are given for the Sivers asymmetry and for all the three ``quark polarimeters'' presently used in COMPASS to measure the transversity distributions. The Collins and the Sivers asymmetries for charged hadrons turn out to be compatible with zero, within the small (~1%) statistical errors, at variance with the results from HERMES on a transversely polarised proton target. Similar results have been obtained for the two hadron asymmetries and for the Lambda polarisation. First attempts to describe the Collins and the Sivers asymmetries measured by COMPASS and HERMES allow to give a consistent picture of these transverse spin effects.

Anna Martin

2007-02-01

96

Downconversion quantum interface for a single quantum dot spin and 1550-nm single-photon channel  

NASA Astrophysics Data System (ADS)

Long-distance quantum communication networks require appropriate interfaces between matter qubit-based nodes and low-loss photonic quantum channels. We implement a downconversion quantum interface, where the single photons emitted from a semiconductor quantum dot at 910 nm are downconverted to 1560 nm using a fiber-coupled periodically poled lithium niobate waveguide and a 2.2-$\\mu$m pulsed pump laser. The single-photon character of the quantum dot emission is preserved during the downconversion process: we measure a cross-correlation $g^{(2)}(\\tau = 0) = 0.17$ using resonant excitation of the quantum dot. We show that the downconversion interface is fully compatible with coherent optical control of the quantum dot electron spin through the observation of Rabi oscillations in the downconverted photon counts. These results represent a critical step towards a long-distance hybrid quantum network in which subsystems operating at different wavelengths are connected through quantum frequency conversion devices and 1.5-$\\mu$m quantum channels.

Pelc, Jason S.; Yu, Leo; De Greve, Kristiaan; McMahon, Peter L.; Natarajan, Chandra M.; Esfandyarpour, Vahid; Maier, Sebastian; Schneider, Christian; Kamp, Martin; Höfling, Sven; Hadfield, Robert H.; Forchel, Alfred; Yamamoto, Yoshihisa; Fejer, M. M.

2012-12-01

97

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

E-print Network

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.

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

2014-10-09

98

Measurement of the spin diffusion rate of dipolar order in single crystal calcium fluoride  

E-print Network

This thesis reports on the first measurement of the spin diffusion rate of a two-spin correlated state, known as dipolar order, in a single crystal of calcium fluoride. The experimental results for the component of the ...

Boutis, Gregory Steven, 1975-

2002-01-01

99

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

NASA Astrophysics Data System (ADS)

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.

Goryca, Mateusz

2010-02-01

100

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

101

Nondestructive optical probe of coherent single spin dynamics in a quantum dot  

NASA Astrophysics Data System (ADS)

Understanding the coherent dynamics of a single electron spin in a quantum dot (QD) is important for potential applications in solid-state, spin-based quantum information processing. Here, results will be presented focusing on optical detection of a single spin and observation of the temporal evolution of the spin state. First, we demonstrate the detection of a single electron spin in a QD using a continuously averaged magneto-optical Kerr rotation (KR) measurement ootnotetextJ. Berezovsky, M. H. Mikkelsen, et al., Science 314, 1916 (2006).. In contrast to many other single spin detection schemes, the KR measurement minimally disturbs the system, making it potentially useful for exploring quantum measurementphenomena or spin-photon entanglement. This continuous single QD KR technique is then extended into the time domain using pulsed pump and probe lasers, allowing the observation of the coherent evolution of an electron spin state with nanosecond temporal resolution ootnotetextM. H. Mikkelsen, J. Berezovsky, et al., Nature Physics 3, 770 (2007).. This provides a direct measurement of the electron g-factor and spin lifetime, and additionally serves as a sensitive probe of the local nuclear spin environment. Finally, we perform ultrafast coherent optical manipulation of the electron spin state in the QD using the optical Stark effect ootnotetextJ. Berezovsky, M. H. Mikkelsen, et al., submitted (2007)., where an off-resonant optical pulse induces rotations of the spin state through angles up to ? radians on picosecond timescales.

Berezovsky, Jesse

2008-03-01

102

Fidelity of optically induced single-spin rotations in semiconductor quantum dots in the presence of nuclear spins  

NASA Astrophysics Data System (ADS)

We examine the influence of nuclear spins on the performance of optically induced rotations of single electron spins in semiconductor quantum dots. We consider Raman type optical transitions between electron spin states and take into account the additional effect of the Overhauser field. We calculate average fidelities of rotations around characteristic axes in the presence of nuclear spins analytically with perturbation theory up to second order in the Overhauser field. Moreover, we calculate the fidelity using numerical averaging over the nuclear field distribution, including arbitrary orders of the hyperfine interaction.

Hildmann, Julia; Burkard, Guido

2014-09-01

103

Anti-Spin Control for Marine Propulsion Systems  

Microsoft Academic Search

An anti-spin controller for marine propulsion systems in rough seas is developed. From measurements of motor torque and propeller shaft speed, an observer providing an accurate estimate of the propeller load torque is used to calculate an estimate of the torque loss. A monitoring algo- rithm utilizing the estimated torque loss detects ventilation incidents, and activates the anti-spin control action.

Øyvind N. Smogeli; Jostein Hansen; Asgeir J. Sørensen; Tor Arne Johansen

104

Controlled Quantum State Transfer in a Spin Chain  

Microsoft Academic Search

Control of the transfer of quantum information encoded in quantum wavepackets moving along a spin chain is demonstrated. Specifically, based on a relationship with control in a paradigm of quantum chaos, it is shown that wavepackets with slow dispersion can automatically emerge from a class of initial superposition states involving only a few spins, and that arbitrary unspecified travelling wavepackets

Jiangbin Gong; Paul Brumer

2007-01-01

105

Controlled quantum-state transfer in a spin chain  

Microsoft Academic Search

Control of the transfer of quantum information encoded in quantum wave packets moving along a spin chain is demonstrated. Specifically, based on a relationship with control in a paradigm of quantum chaos, it is shown that wave packets with slow dispersion can automatically emerge from a class of initial superposition states involving only a few spins, and that arbitrary unspecified

Jiangbin Gong; Paul Brumer

2007-01-01

106

Coherent Spin Transport and Suppression of Spin Relaxation in InSb Nanowires with Single Subband Occupancy at Room Temperature.  

PubMed

A longstanding goal of spintronics is to inject, then coherently transport, and finally detect electron spins in a semiconductor nanowire in which a single quantized subband is occupied by the electrons at room temperature. Here, the achieving of this goal in electrochemically self-assembled 50-nm diameter InSb nanowires is reported and substantiated by demonstrating both the spin-valve effect and the Hanle effect. Observing both effects in the same sample allows one to estimate the electron mobility and the spin relaxation time in the nanowires. It is found that despite four orders of magnitude degradation in the mobility compared to bulk or quantum wells and a resulting four orders of magnitude increase in the Elliott-Yafet spin relaxation rate, the spin relaxation time in the nanowires is still about an order of magnitude longer than what has been reported in bulk and quantum wells. This is caused by the elimination or suppression of the D'yakonov-Perel' spin relaxation through single subband occupancy. These experiments shed light on the nature of spin transport in a true quantum wire and raise hopes for the realization of a room-temperature Datta-Das spin transistor, where single subband occupancy is critical for optimum performance. PMID:25048330

Bandyopadhyay, Saumil; Hossain, Md Iftekhar; Ahmad, Hasnain; Atulasimha, Jayasimha; Bandyopadhyay, Supriyo

2014-11-01

107

Distinguishing between Nonorthogonal Quantum States of a Single Nuclear Spin  

NASA Astrophysics Data System (ADS)

An important task for quantum-information processing is optimal discrimination between two nonorthogonal quantum states, which until now has been realized only optically. Here, we present and compare experimental realizations of optimal quantum measurements for distinguishing between two nonorthogonal quantum states encoded in a single N14 nuclear spin at a nitrogen-vacancy defect in diamond. Implemented measurement schemes are the minimum-error measurement (known as Helstrom measurement), unambiguous state discrimination using a standard projective measurement, and optimal unambiguous state discrimination [known as Ivanovic-Dieks-Peres (IDP) measurement], which utilizes a three-dimensional Hilbert space. This allows us to benchmark the IDP measurement against the standard projective measurements. Measurement efficiencies are found to be above 80% for all schemes and reach a value of 90% for the IDP measurement.

Waldherr, Gerald; Dada, Adetunmise C.; Neumann, Philipp; Jelezko, Fedor; Andersson, Erika; Wrachtrup, Jörg

2012-11-01

108

Effective ergodicity in single-spin-flip dynamics  

NASA Astrophysics Data System (ADS)

A quantitative measure of convergence to effective ergodicity, the Thirumalai-Mountain (TM) metric, is applied to Metropolis and Glauber single-spin-flip dynamics. In computing this measure, finite lattice ensemble averages are obtained using the exact solution for a one dimensional Ising model, whereas the time averages are computed with Monte Carlo simulations. The time evolution of the effective ergodic convergence of Ising magnetization is monitored. By this approach, diffusion regimes of the effective ergodic convergence of magnetization are identified for different lattice sizes, nonzero temperature, and nonzero external field values. Results show that caution should be taken when using the TM metric at system parameters that give rise to strong correlations.

Süzen, Mehmet

2014-09-01

109

Hadronic single spin asymmetries at large P sub T  

SciTech Connect

We present a dynamical explanation of the single transverse-spin asymmetry for the process {ital pN}{r arrow}{Lambda}{sup 0{up arrow}}{ital X}, with the {Lambda}{sup 0} observed at large angles. The polarisation arises by considering the {Lambda}{sup 0} to be produced either directly or via the virtual dissociation of a parent baryon. Our results reproduce very well both the measured {ital p}{sub {ital T}} and {ital x}{sub {ital F}} dependence of the polarisation. We also include a discussion of the left-right asymmetry in pion production off a polarised target: {ital pN}{sup {up arrow}}{r arrow}{pi}{ital X}.

Ratcliffe, P.G. (INFN, Sezione di Milano, Via Celoria 16, 20133 Milano (Italy))

1991-04-20

110

Spatiotemporally controlled single cell sonoporation  

PubMed Central

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

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

2012-01-01

111

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

SciTech Connect

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

Wang Hai; Li Shujing; Xu Zhongxiao; Zhao Xingbo; Zhang Lijun; Li Jiahua; Wu Yuelong; Xie Changde; Peng Kunchi [State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 (China); Xiao Min [The State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 (China); Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

2011-04-15

112

Decoherence of a single-ion qubit immersed in a spin-polarized atomic bath.  

PubMed

We report on the immersion of a spin qubit encoded in a single trapped ion into a spin-polarized neutral atom environment, which possesses both continuous (motional) and discrete (spin) degrees of freedom. The environment offers the possibility of a precise microscopic description, which allows us to understand dynamics and decoherence from first principles. We observe the spin dynamics of the qubit and measure the decoherence times (T(1) and T(2)), which are determined by the spin-exchange interaction as well as by an unexpectedly strong spin-nonconserving coupling mechanism. PMID:23679585

Ratschbacher, L; Sias, C; Carcagni, L; Silver, J M; Zipkes, C; Köhl, M

2013-04-19

113

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

E-print Network

This dissertation studies spin squeezing, entanglement and decoherence in large ensembles of cold, trapped alkali atoms with hyperfine spin f interacting with optical fields. Restricting the state of each atom to a qutrit embedded in the 2f+1 dimensional hyperfine spin enables us to efficiently model the coherent and dissipative dynamics of the ensemble. This formalism also allows us to explore the effects of local control on the internal hyperfine spins of the atoms. State preparation using such control increases the entangling power of the atom-light interface for f>1/2. Subsequent control of the internal spins converts entanglement into metrologically relevant spin squeezing. In the case of squeezing by quantum nondemolition measurement, we employ a numerical search to find state preparations that maximize spin squeezing in the presence of decoherence. Dissipative dynamics on our system include optical pumping due to spontaneous emission. While most works ignore optical pumping or treat it phenomenologically, we employ a master equation derived from first principles. This work is extended to the case of an atomic ensemble interacting with a non-homogeneous paraxial probe. The geometries of the ensemble and the probe are optimized to maximize both spatial mode matching and spin squeezing.

Leigh M. Norris

2014-10-01

114

Spin Solitons and Quantum Control of Spin Chain Dynamics  

Microsoft Academic Search

Experiments in coherent spectroscopy correspond to control of quantum mechanical ensembles guiding them from initial to final target states by unitary transformations. The control inputs (pulse sequences) that accomplish these unitary transformations should take as little time as possible so as to minimize the effects of relaxation and to optimize the sensitivity of the experiments. Here, we present a radically

Navin Khaneja; Steffen J. Glaser

2002-01-01

115

Subriemannian geodesics and optimal control of spin systems  

Microsoft Academic Search

Nuclear Magnetic Resonance (NMR) Spectroscopy in solution is an important modality for extracting structural information of macromolecules. In NMR spectroscopy, radio frequency electromagnetic pulses axe used to manipulate spin states of atomic nuclei. Pulse sequences that accomplish a desired spin control should be as short as possible in order to minimize the effects of thermal relaxation, and to optimize the

Navin Khaneja; Steffen Glaser; Roger Brockett

2002-01-01

116

Dual-spin attitude control for outer planet missions  

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

117

Control of single-stage single-phase PV inverter  

Microsoft Academic Search

In this paper the issue of control strategies for single-stage photovoltaic (PV) inverter is addressed. Two different current controllers have been implemented and an experimental comparison between them has been made. A complete control structure for the single-phase PV system is also presented. The main elements of the PV control structure are: - a maximum power point tracker (MPPT) algorithm

M. Ciobotaru; R. Teodorescu; F. Blaabjerg

2005-01-01

118

Terahertz spin current pulses controlled by magnetic heterostructures.  

PubMed

In spin-based electronics, information is encoded by the spin state of electron bunches. Processing this information requires the controlled transport of spin angular momentum through a solid, preferably at frequencies reaching the so far unexplored terahertz regime. Here, we demonstrate, by experiment and theory, that the temporal shape of femtosecond spin current bursts can be manipulated by using specifically designed magnetic heterostructures. A laser pulse is used to drive spins from a ferromagnetic iron thin film into a non-magnetic cap layer that has either low (ruthenium) or high (gold) electron mobility. The resulting transient spin current is detected by means of an ultrafast, contactless amperemeter based on the inverse spin Hall effect, which converts the spin flow into a terahertz electromagnetic pulse. We find that the ruthenium cap layer yields a considerably longer spin current pulse because electrons are injected into ruthenium d states, which have a much lower mobility than gold sp states. Thus, spin current pulses and the resulting terahertz transients can be shaped by tailoring magnetic heterostructures, which opens the door to engineering high-speed spintronic devices and, potentially, broadband terahertz emitters. PMID:23542903

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

2013-04-01

119

Controllable spin transport in dual-gated silicene  

NASA Astrophysics Data System (ADS)

Based on the dual-gated silicene, we have evaluated theoretically the spin-dependent transport in lateral resonant tunneling structure. By aligning the completely valley-polarized beam with spin-resolved well state in concerned structure, large spin polarization can be expected owing to spin-dependent resonant tunneling mechanism. Under the gate electric field modulation, the forming quantum well state can be externally manipulated, triggering further the emergence of externally-controllable spin polarization. Importantly, integrating the considered structure with a proper valley-filter, which might be constructed from valley-contrasting physics as that in graphene valleytronics, completely-polarized spin beam can also be attained without the assistance of ferromagnetic component, providing thus some profitable strategies to develop nonmagnetic spintronic devices residing on silicene.

Wang, Yu; Lou, Yiyi

2014-07-01

120

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

PubMed Central

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

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

2014-01-01

121

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

122

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

PubMed Central

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 center’s 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

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

2013-01-01

123

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

124

Spin free analytic platform type guidance and control system  

NASA Astrophysics Data System (ADS)

The components of the spin free analytic satellite guidance and control system (SFAP) used for attitude reference on the M-3S Japanese launch vehicles are described. SFAP consists of attitude reference, control electronics, and actuators for each of three rocket stages. The attitude reference is performed with a single axis stabilized platform and three rate integrating gyroscopes mounted orthogonally to each other on the table. One gyro, aligned with the table axis, serves as the torque signal source. The gyros have a pulse output, each corresponding to a 2 x 10 to the -16th radian pitch/yaw attitude change. The electronic compare pitch, roll, and yaw angles with preset values, that are amenable to changes through ground control signals. The actuators include linear thrust vector controls (TVC) on the side of the first stage nozzle and an on/off system on the side of the second stage nozzle, together with hydrogen peroxide jets. Separate programs control each stage, and performance has been nominal in flight testing.

Higashiguchi, M.; Ishitani, H.

125

Photonic transport control by spin-optical disordered metasurface  

E-print Network

Photonic metasurfaces are ultrathin electromagnetic wave-molding metamaterials providing the missing link for the integration of nanophotonic chips with nanoelectronic circuits. An extra twist in this field originates from spin-optical metasurfaces providing the photon spin (polarization helicity) as an additional degree of freedom in light-matter interactions at the nanoscale. Here we report on a generic concept to control the photonic transport by disordered (random) metasurfaces with a custom-tailored geometric phase. This approach combines the peculiarity of random patterns to support extraordinary information capacity within the intrinsic limit of speckle noise, and the optical spin control in the geometric phase mechanism, simply implemented in two-dimensional structured matter. By manipulating the local orientations of anisotropic optical nanoantennas, we observe spin-dependent near-field and free-space open channels, generating state-of-the-art multiplexing and interconnects. Spin-optical disordered m...

Veksler, Dekel; Ozeri, Dror; Shitrit, Nir; Kleiner, Vladimir; Hasman, Erez

2014-01-01

126

Entanglement Controlled Single-Electron Transmittivity  

E-print Network

We consider a system consisting of single electrons moving along a 1D wire in the presence of two magnetic impurities. Such system shows strong analogies with a Fabry - Perot interferometer in which the impurities play the role of two mirrors with a quantum degree of freedom: the spin. We have analysed the electron transmittivity of the wire in the presence of entanglement between the impurity spins. The main result of our analysis is that, for suitable values of the electron momentum, there are two maximally entangled state of the impurity spins the first of which makes the wire transparent whatever the electron spin state while the other strongly inhibits the electron transmittivity. Such predicted striking effect is experimentally observable with present day technology.

Francesco Ciccarello; Massimo Palma; Michelangelo Zarcone; Yasser Omar; Vitor Rocha Vieira

2006-03-17

127

Spin-path entanglement in single-neutron interferometer experiments  

SciTech Connect

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.

Hasegawa, Yuji; Erdoesi, Daniel [Atominstitut, Vienna University of Technology, Stadionallee 2, A-1020 Wien (Austria)

2011-09-23

128

Electric Control of Spin Helicity in a Magnetic Ferroelectric  

SciTech Connect

Magnetic ferroelectrics or multiferroics, which are currently extensively explored, may provide a good arena to realize a novel magnetoelectric function. Here we demonstrate the genuine electric control of the spiral magnetic structure in one such magnetic ferroelectric, TbMnO{sub 3}. A spin-polarized neutron scattering experiment clearly shows that the spin helicity, clockwise or counterclockwise, is controlled by the direction of spontaneous polarization and hence by the polarity of the small electric field applied on cooling.

Yamasaki, Y.; Goto, T. [Department of Applied Physics, University of Tokyo, Tokyo 113-8656 (Japan); Sagayama, H. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Matsuura, M.; Hirota, K. [Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581 (Japan); Arima, T. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Spin Superstructure Project, ERATO, Japan Science and Technology Agency, Tsukuba 305-8562 (Japan); Tokura, Y. [Department of Applied Physics, University of Tokyo, Tokyo 113-8656 (Japan); Spin Superstructure Project, ERATO, Japan Science and Technology Agency, Tsukuba 305-8562 (Japan); Correlated Electron Research Center (CERC), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8562 (Japan)

2007-04-06

129

Active control of thermal transport in molecular spin valves  

NASA Astrophysics Data System (ADS)

Active control of heat flow is challenging. We demonstrate that molecular spin valves offer a unique opportunity for achieving this goal. Our first-principles calculations of the transport of electrons and phonons in nickel-benzenedithiol-nickel junctions show that when the magnetization direction of the electrodes is changed from parallel to antiparallel the junctions become thermally insulating. Our findings, therefore, suggest a novel avenue for actively controlling thermal transport via the spin degree of freedom.

Lee, Myeong H.; Dunietz, Barry D.

2013-07-01

130

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

PubMed Central

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

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

2012-01-01

131

Coherent control of opticallyinjected population spin in (111)-GaAs  

E-print Network

, respectively;PEM is a photoelastic modulator used to modulate the probe polarization; L and M are a lens polarization combinations and crystal orientations. 02002 Optical Societyof America OCIS codes: (190 and control of a spin-polarized carrier population through quantum interference of single photon absorption

Sipe,J. E.

132

Gate-controlled electron spins in quantum dots  

SciTech Connect

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.

Prabhakar, Sanjay [M2NeT Laboratory, Wilfrid Laurier University, Waterloo, ON, N2L3C5 (Canada); Melnik, Roderick [M2NeT Laboratory, Wilfrid Laurier University, Waterloo, ON, N2L3C5 and Gregorio Millan Institute, Universidad Carlos III de Madrid, 28911, Leganes (Spain); Bonilla, Luis L. [Gregorio Millan Institute, Universidad Carlos III de Madrid, 28911, Leganes, Spain and School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138 (United States)

2013-12-16

133

Low temperature spin glass transition in Gallium ferrite single crystals  

NASA Astrophysics Data System (ADS)

Magnetoelectric gallium ferrite (GaFeO3 or GFO) manifests close to room temperature ferrimagnetism owing to inherent cationic site disorder in an otherwise antiferromagnetic ground state structure. In GFO, Fe ions at Fe1 and Fe2 sites are antiferromagnetically coupled while Fe and Ga at Fe2 and Ga2 sites respectively are ferromagnetically coupled. Ga1 site is magnetically inactive. Here, we present a detailed study to probe phase transitions in GFO using ac and dc magnetic characterization methods to demonstrate spin glass behavior in GFO below 200 K. Our dc magnetization measurement exhibits that while GFO undergoes standard para (PM) to ferromagnetic (fM) transition at Tc ˜ 290 K, splitting between field cooled and zero-field cooled plots is observed at low temperatures hinting at the spin-glass like behavior. Further, temperature dependent ac susceptibility measurements at different frequencies and at different dc fields demonstrate that the system exhibits a non-equilibrium canonical spin glass (SG) state below the spin glass transition temperature ˜ 210 K. The spin glass state has been further characterized by memory effect and aging measurements. The origin of such a spin-glass phase is proposed to arise from a network of geometrically frustrated spin system attributed to combination of antiferromagnetic interaction among the Fe ions in the two Fe sites and Ga2 site as well as inherent cation site disorder.

Mukherjee, Somdutta; Gupta, Rajeev; Garg, Ashish

2012-02-01

134

Study of thermally induced spin state transition in NdCoO3 single crystal  

NASA Astrophysics Data System (ADS)

We have carried out Magnetization, Raman spectroscopy and IR spectroscopy studies as a function of temperature to investigate the spin state transition in NdCoO3 single crystal. The crystal has been grown by Optical Float Zone technique and characterized by Synchrotron X-ray Diffraction. Our results indicate that the spin crossover from low spin state (LS) to intermediate spin state (IS) occurs continuously over a wide range of temperature above 200K. The wide temperature range of the spin crossover reflects possible electronic or magnetic in-homogeneity at the microscopic level, which is a common feature of some cobalt perovskites. The magnetization studies indicate a spin gap which is higher than that of LaCoO3 (180 K) and Raman spectroscopy studies reveal a Jahn Teller vibration mode characteristic of the intermediate spin state similar to that reported for LaCoO3 in literature.

Janaki, J.; Nithya, R.; Ganesamoorthy, S.; Sairam, T. N.; Ravindran, T. R.; Vinod, K.; Bharathi, A.

2013-02-01

135

Theory of Spin Waves in Heisenberg Ferromagnetic and Antiferromagnetic Thin Films with Nonuniaxial Single - Anisotropy  

Microsoft Academic Search

This thesis describes the microscopic, quantum mechanical theory of exchange-dominated spin waves in Heisenberg ferromagnetic and antiferromagnetic thin films including the effects of nonuniaxial single-ion anisotropy. The results constitute a generalization of previous theoretical studies on spin waves in thin films with uniaxial anisotropy and in semi-infinite ferromagnets with nonuniaxial anisotropy. A spin Hamiltonian containing nearest-neighbour exchange terms, Zeeman terms,

Paula R. L. Heron

1995-01-01

136

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

E-print Network

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 LIGO'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.

Ian Harry; Stephen Fairhurst

2011-01-07

137

Single-spin beam asymmetry in semi-exclusive deep-inelastic electroproduction  

SciTech Connect

Recent measurements from Jefferson Lab show significant beam single spin asymmetries in deep inelastic scattering. The asymmetry is due to interference of longitudinal and transverse photoabsorption amplitudes which have different phases induced by the final-state interaction between the struck quark and the target spectators. We developed a dynamical model for a single-spin beam asymmetry in deep-inelastic scattering. Our results are consistent with the experimentally observed magnitude of this effect. We conclude that similar mechanisms involving quark orbital angular momentum ('Sivers effect') are responsible for both target and beam single-spin asymmetries.

Andrei Afanasev; C. E. Carlson

2003-05-01

138

Two-photon Exchange Corrections to Single Spin Asymmetry of Neutron and $^3$He  

E-print Network

In a simple hadronic model, the two-photon exchange contributions to the single spin asymmetries for the nucleon and the $^3$He are estimated. The results show that the elastic contributions of two-photon exchange to the the single spin asymmetries for the nucleon are rather small while those for the $^3$He are relatively large. Besides the strong angular dependence, the two-photon contributions to the single spin asymmetry for the $^3$He are very sensitive to the momentum transfer.

Dian-Yong Chen; Yu-Bing Dong

2009-11-26

139

Scanning localized magnetic fields in a microfluidic device using single spin in a nano-diamond  

E-print Network

Nitrogen vacancy (NV) color centers in diamond have emerged as highly versatile optical emitters that exhibit room temperature spin properties. These characteristics make NV centers ideal for magnetometry which plays an important role in a broad range of chemical and biological sensing applications. The integration of NV magnetometers with microfluidic systems could enable the study of isolated chemical and biological samples in a fluid environment with high spatial resolution. Here we demonstrate a method to perform localized magnetometry with nanometer spatial precision using a single NV center in a microfluidic device. We manipulate a magnetic particle within a liquid environment using a combination of planar flow control and vertical magnetic actuation to achieve 3-dimensional manipulation. A diamond nanocrystal containing a single NV center is deposited in the microfluidic channels and acts as a local magnetic field probe. We map out the magnetic field distribution of the magnetic particle by varying its...

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

2014-01-01

140

Optically detected coherent spin dynamics of a single electron in a quantum dot  

E-print Network

LETTERS Optically detected coherent spin dynamics of a single electron in a quantum dot M. H dynamics provide a sensitive probe of the local nuclear spin environment. The magneto-optical Kerr effect, Schematic diagram of the experimental set-up (EOM, electro-optic modulator; Pol. BS, polarizing beam

Loss, Daniel

141

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

SciTech Connect

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.

Sola, Ignacio R.; Gonzalez-Vazquez, Jesus; Malinovsky, Vladimir S. [Departamento de Quimica Fisica I, Universidad Complutense, 28040 Madrid (Spain); MagiQ Technologies Inc., 171 Madison Avenue, Suite 1300, New York, New York 10016 (United States)

2006-10-15

142

Observation of quantum jumps of a single quantum dot spin using sub-microsecond single-shot optical readout  

E-print Network

Single-shot read-out of individual qubits is typically the slowest process among the elementary single- and two-qubit operations required for quantum information processing. Here, we use resonance fluorescence from a single-electron charged quantum dot to read-out the spin-qubit state in 800 nanoseconds with a fidelity exceeding 80%. Observation of the spin evolution on longer timescales reveals quantum jumps of the spin state: we use the experimentally determined waiting-time distribution to characterize the quantum jumps. Embedding a quantum dot in a photonic nanostructure could be used to enhance the collection efficiency by a factor of 10, enabling single-shot read-out with a fidelity exceeding 97%.

Aymeric Delteil; Wei-bo Gao; Parisa Fallahi; Javier Miguel-Sanchez; Atac Imamoglu

2013-10-31

143

Galileo dual-spin attitude and articulation control system  

NASA Technical Reports Server (NTRS)

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.

Ward, R. S.

1978-01-01

144

On the anatomy of multi-spin magnon and single spike string solutions  

E-print Network

We study rigid string solutions rotating in $AdS_5\\times S^5$ background. For particular values of the parameters of the solutions we find multispin solutions corresponding to giant magnons and single spike strings. We present an analysis of the dispersion relations in the case of three spin solutions distributed only in $S^5$ and the case of one spin in $AdS_5$ and two spins in $S^5$. The possible relation of these string solutions to gauge theory operators and spin chains are briefly discussed.

H. Dimov; R. C. Rashkov

2007-09-26

145

Optimal and suboptimal control technique for aircraft spin recovery  

NASA Technical Reports Server (NTRS)

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.

Young, J. W.

1974-01-01

146

Temperature induced Spin Switching in SmFeO3 Single Crystal  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

147

Temperature induced spin switching in SmFeO3 single crystal.  

PubMed

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

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

2014-01-01

148

Large magnetoresistance through a single molecule due to a spin-split hybridized orbital.  

PubMed

Using organic materials in spintronic devices raises a lot of expectation for future applications due to their flexibility, low cost, long spin lifetime, and easy functionalization. However, the interfacial hybridization and spin polarization between the organic layer and the ferromagnetic electrodes still has to be understood at the molecular scale. Coupling state-of-the-art spin-polarized scanning tunneling spectroscopy and spin-resolved ab initio calculations, we give the first experimental evidence of the spin splitting of a molecular orbital on a single non magnetic C(60) molecule in contact with a magnetic material, namely, the Cr(001) surface. This hybridized molecular state is responsible for an inversion of sign of the tunneling magnetoresistance depending on energy. This result opens the way to spin filtering through molecular orbitals. PMID:22827486

Kawahara, S L; Lagoute, J; Repain, V; Chacon, C; Girard, Y; Rousset, S; Smogunov, A; Barreteau, C

2012-09-12

149

Energy levels and decoherence properties of single electron and nuclear spins in a defect center in diamond  

E-print Network

The coherent behavior of the single electron and single nuclear spins of a defect center in diamond and a 13C nucleus in its vicinity, respectively, are investigated. The energy levels associated with the hyperfine coupling of the electron spin of the defect center to the 13C nuclear spin are analyzed. Methods of magnetic resonance together with optical readout of single defect centers have been applied in order to observe the coherent dynamics of the electron and nuclear spins. Long coherence times, in the order of microseconds for electron spins and tens of microseconds for nuclear spins, recommend the studied system as a good experimental approach for implementing a 2-qubit gate.

I. Popa; T. Gaebel; M. Domhan; C. Wittmann; F. Jelezko; J. Wrachtrup

2004-09-12

150

Spin hot spots in single-electron GaAs-based quantum dots  

NASA Astrophysics Data System (ADS)

Spin relaxation of a single electron in a weakly coupled double quantum dot is calculated numerically. The phonon assisted spin flip is allowed by the presence of the linear and cubic spin-orbit couplings and nuclear spins. The rate is calculated as a function of the interdot coupling, the magnetic field strength and orientation, and the dot bias. In an in-plane magnetic field, the rate is strongly anisotropic with respect to the magnetic field orientation, due to the anisotropy of the spin-orbit interactions. The nuclear spin influence is negligible. In an out-of-plane field, the nuclear spins play a more important role due selection rules imposed on the spin-orbit couplings. Our theory shows a very good agreement with data measured in [Srinivasa, et al., PRL 110, 196803 (2013)], allowing us to extract information on the linear spin-orbit interactions strengths in that experiment. We estimate that they correspond to spin-orbit lengths of about 5-15 $\\mu$m.

Raith, Martin; Pangerl, Thomas; Stano, Peter; Fabian, Jaroslav

2014-09-01

151

Magnetoelectric control of spin-chiral ferroelectric domains in a triangular lattice antiferromagnet  

NASA Astrophysics Data System (ADS)

We have grown single crystals of a triangular lattice antiferromagnet (TLA), CuCrO2 , and investigated the correlation between magnetic and dielectric properties. Two magnetic phase transitions are observed at TN2?24.2K and TN1?23.6K . It was found that ferroelectric polarization along the triangular lattice plane develops at TN1 , suggesting that the system undergoes a transition into an out-of-plane 120° spin-chiral phase at TN1 . The TLA provides an opportunity for unique magnetoelectric control of spin-chiral ferroelectric domain structures by means of electric and/or magnetic fields.

Kimura, Kenta; Nakamura, Hiroyuki; Ohgushi, Kenya; Kimura, Tsuyoshi

2008-10-01

152

Coherent control of spin precession motion with impulsive magnetic fields of half-cycle terahertz radiation.  

PubMed

Coherent control of the precession motion of magnetizations in a single crystal YFeO3 with double half-cycle pulse terahertz waves was demonstrated. Quasiferromagnetic (0.299 THz) and quasiantiferromagnetic (0.527 THz) precession modes were selectively excited by choosing an appropriate interval of two pulses and were observed as free induction decay (FID) signals from the spin system. By observing the circularly polarized FID signals due to ferromagnetic resonance, we also succeeded in confirming directly the energy storage in the spin system and recovery from that to the electromagnetic radiation. PMID:21231498

Yamaguchi, Keita; Nakajima, Makoto; Suemoto, Tohru

2010-12-01

153

Nanoscale broadband transmission lines for spin qubit control  

NASA Astrophysics Data System (ADS)

The intense interest in spin-based quantum information processing has caused an increasing overlap between the two traditionally distinct disciplines of magnetic resonance and nanotechnology. In this work we discuss rigorous design guidelines to integrate microwave circuits with charge-sensitive nanostructures, and describe how to simulate such structures accurately and efficiently. We present a new design for an on-chip, broadband, nanoscale microwave line that optimizes the magnetic field used to drive a spin-based quantum bit (or qubit) while minimizing the disturbance to a nearby charge sensor. This new structure was successfully employed in a single-spin qubit experiment, and shows that the simulations accurately predict the magnetic field values even at frequencies as high as 30 GHz.

Dehollain, J. P.; Pla, J. J.; Siew, E.; Tan, K. Y.; Dzurak, A. S.; Morello, A.

2013-01-01

154

Control of the spin geometric phase in semiconductor quantum rings  

PubMed Central

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. PMID:24067870

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

2013-01-01

155

Mode locking of electron spin coherence in singly charged quantum dots  

NASA Astrophysics Data System (ADS)

Fast dephasing of electron spins in an ensemble of quantum dots is detrimental for applications in quantum-information processing. We show that dephasing can be overcome by using a periodic train of light pulses to synchronize the phases of the precessing spins, and demonstrate this effect in an ensemble of singly charged (In,Ga)As/GaAs quantum dots. A periodic train of circularly polarized light pulses from a mode-locked laser synchronizes the precession of the spins to the laser repetition rate, transferring the mode-locking into the spin system. The mode-locking technique allows us to measure the single-spin coherence time to be 3 microseconds, which is four orders of magnitude longer than the ensemble dephasing time of 400 picoseconds. The technique also offers the possibility of achieving all-optical coherent manipulation of spin ensembles, in which electron spins can be clocked by two trains of pump pulses with a fixed temporal delay. The nuclei in these experiments act constructively, leading to the nuclear-induced frequency-focusing effect, which moves the electron-spin precession into dephasing-free subspace.

Efros, Alexander

2008-10-01

156

3He spin filters for spherical neutron polarimetry at the hot neutrons single crystal diffractometer POLI-HEiDi  

NASA Astrophysics Data System (ADS)

3D vector polarisation analysis called also SNP (Spherical Neutron Polarimetry) is a powerful method for the detailed investigation of complex magnetic structures. The precise control of the incoming and scattered neutron polarisations is essential for this technique. Here we show an instrumental setup, that was recently implemented on the new single crystal diffractometer POLI-HEiDi at the FRM II for performing SNP experiments using two 3He spin filters for the production and for the analysis of the neutron polarisation. The design and optimisation procedure for the used spin filter cells are presented. Methods for in-situ measurements of the incoming polarisation as well as the particularities of the using two spin filters and corrections for the time dependent relaxation are discussed. Statistical precision of 1% has been achieved for the measurements of the polarisation matrix under the real experimental conditions using described cells and applying proposed correction method for the data.

Hutanu, V.; Meven, M.; Masalovich, S.; Heger, G.; Roth, G.

2011-06-01

157

Enhanced Spin Squeezing Through Quantum Control of Qudits  

NASA Astrophysics Data System (ADS)

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.

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

2012-06-01

158

Enhanced Spin Squeezing Through Quantum Control of Qudits  

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

159

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

PubMed

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

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

2010-07-28

160

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

PubMed Central

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

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

2013-01-01

161

Single-spin asymmetries in inclusive DIS and in hadronic collisions  

SciTech Connect

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 T{sub F}. Using different parameterizations for T{sub F} 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.

Metz, Andreas; Pitonyak, Daniel [Department of Physics, Temple University, Philadelphia, PA 19122 (United States); Schaefer, Andreas; Zhou, Jian [Institute for Theoretical Physics, Regensburg University, 93053 Regensburg (Germany); Schlegel, Marc; Vogelsang, Werner [Institute for Theoretical Physics, Tuebingen University, 72076 Tuebingen (Germany)

2013-04-15

162

Transverse single spin asymmetries at small x and the anomalous magnetic moment  

NASA Astrophysics Data System (ADS)

We show that in the McLerran-Venugopalan model an axial asymmetrical valence quark distributions in the transverse plane of a transversely polarized proton can give rise to a spin-dependent odderon. Such polarized odderon is responsible for the transverse single spin asymmetries for jet production in the backward region of pp collisions and open charm production in the semi-inclusive deep inelastic scattering process.

Zhou, Jian

2014-04-01

163

Magnetic field induced discontinuous spin reorientation in ErFeO{sub 3} single crystal  

SciTech Connect

The spin reorientation of ErFeO{sub 3} that spontaneously occurs at low temperature has been previously determined to be a process involving the continuous rotation of Fe{sup 3+} spins. In this work, the dynamic process of spin reorientation in ErFeO{sub 3} single crystal has been investigated by AC susceptibility measurements at various frequencies and static magnetic fields. Interestingly, two completely discontinuous steps are induced by a relatively large static magnetic field due to the variation in the magnetic anisotropy during this process. It provides deeper insights into the intriguing magnetic exchange interactions which dominate the sophisticated magnetic phase transitions in the orthoferrite systems.

Shen, Hui [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China) [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China); Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2500 (Australia); Cheng, Zhenxiang, E-mail: cheng@uow.edu.au; Hong, Fang; Wang, Xiaolin [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2500 (Australia)] [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2500 (Australia); Xu, Jiayue [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China)] [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China); Yuan, Shujuan; Cao, Shixun [Department of Physics, Shanghai University, Shanghai 200444 (China)] [Department of Physics, Shanghai University, Shanghai 200444 (China)

2013-11-04

164

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

SciTech Connect

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.

Dzlieva, E. S.; Karasev, V. Yu., E-mail: plasmadust@yandex.ru [St. Petersburg State University, Institute of Physics (Russian Federation); Petrov, O. F. [Russian Academy of Sciences, Institute for High Energy Densities, Joint Institute for High Temperatures (Russian Federation)

2012-01-15

165

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)

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.

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

1977-01-01

166

Gate control of the electron spin-diffusion length in semiconductor quantum wells  

PubMed Central

The spin diffusion length is a key parameter to describe the transport properties of spin polarized electrons in solids. Electrical spin injection in semiconductor structures, a major issue in spintronics, critically depends on this spin diffusion length. Gate control of the spin diffusion length could be of great importance for the operation of devices based on the electric field manipulation and transport of electron spin. Here we demonstrate that the spin diffusion length in a GaAs quantum well can be electrically controlled. Through the measurement of the spin diffusion coefficient by spin grating spectroscopy and of the spin relaxation time by time-resolved optical orientation experiments, we show that the diffusion length can be increased by more than 200% with an applied gate voltage of 5?V. These experiments allow at the same time the direct simultaneous measurements of both the Rashba and Dresselhaus spin-orbit splittings. PMID:24052071

Wang, G.; Liu, B. L.; Balocchi, A.; Renucci, P.; Zhu, C. R.; Amand, T.; Fontaine, C.; Marie, X.

2013-01-01

167

Optical Detection and Control of Single Magnetic Ions in Photonic Microcavities  

NASA Astrophysics Data System (ADS)

As the density of magnetic information storage scales upwards, the number of magnetic moments in each bit decreases. This pathway ends with the need to manipulate a single spin, a requirement that is also important for nascent information processing schemes including quantum computation. Current demonstrations of coherent single spin control include electron spins in semiconductor quantum dots and nitrogen-vacancy centers in diamond ootnotetextR. Hanson and D. D. Awschalom, Nature 453, 1043 (2008). . Single magnetic ions in semiconductors have also emerged as an intriguing spin system due to their surprising ability to be manipulated in zero-field. Manganese (Mn) ions in gallium arsenide (GaAs) are strongly exchange coupled to the charge carriers and can be rapidly controlled either optically or electrically in bandgap- engineered heterostructures. Recently we demonstrated optical control and readout of a small ensemble of Mn ion spins in a GaAs quantum well without magnetic materials or applied magnetic fieldsootnotetextR. C. Myers, M. H. Mikkelsen, J.-M. Tang, A. C. Gossard, M. E. Flatt'e, and D. D. Awschalom, Nature Materials 7, 203 (2008).. In the limit of low doping levels, their spin lifetimes increase with decreasing concentration as the ions become isolated. Here we describe the spatially-resolved observation and manipulation of isolated Mn spins integrated within photonic microcavities. A single magnetically-doped GaAs quantum well is fabricated within both microdisk and vertical Fabry-Perot cavities in which their respective cavity modes are coupled to the neutral Mn acceptor emission. Scanning micro-photoluminescence measurements reveal cavity-coupled emission and a dramatic increase in the measured signal to noise ratio, thereby allowing direct imaging of narrow linewidth luminescence from the Mn moments. These Mn ion spins are optically polarized at zero-field, exhibit long spin lifetimes, and may be manipulated through a variety of techniques.

Awschalom, David D.

2009-03-01

168

Single Spin Asymmetry in Inclusive Hadron Production in pp Scattering from Collins Mechanism  

SciTech Connect

We study the Collins mechanism contribution to the single transverse spin asymmetry in inclusive hadron production in pp scattering p{up_arrow}p {yields} {pi}X from the leading jet fragmentation. The azimuthal asymmetric distribution of hadron in the jet leads to a single spin asymmetry for the produced hadron in the Lab frame. The effect is evaluated in a transverse momentum dependent model that takes into account the transverse momentum dependence in the fragmentation process. We find the asymmetry is comparable in size to the experimental observation at RHIC at {radical}s = 200GeV.

Yuan, Feng; Yuan, Feng

2008-04-14

169

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

NASA Astrophysics Data System (ADS)

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.

Warburton, Richard

2005-03-01

170

Controllable entanglement transfer via two parallel spin chains  

NASA Astrophysics Data System (ADS)

Transferring quantum states between nearby quantum processors is important for building up a powerful quantum computer. In this paper, we propose a controllable scheme to transfer bipartite entangled states using two open-ended spin-1/2 > chains in parallel as a dual-rail quantum channel. We perform two sets of operations, one on one end of the chains at the beginning of the system evolution and the other on the other end of the chains at the time the transferred entanglement needs to be picked up. Among the operations employed in the scheme there are weak measurements with controllable strengths. By suitably choosing the strengths of these weak measurements, the entanglement transferability is pronouncedly improved, compared to that due to the spin chains' natural dynamics. In principle, the entanglement amount at the receiving site can be made arbitrarily close to that at the sending site, i.e., perfect entanglement transfer could be achieved asymptotically.

Man, Zhong-Xiao; An, Nguyen Ba; Xia, Yun-Jie; Kim, Jaewan

2014-06-01

171

Nanosecond Spin Lifetimes in Single- and Few-Layer Graphene-hBN Heterostructures at Room Temperature.  

PubMed

We present a new fabrication method of graphene spin-valve devices that yields enhanced spin and charge transport properties by improving both the electrode-to-graphene and graphene-to-substrate interface. First, we prepare Co/MgO spin injection electrodes onto Si(++)/SiO2. Thereafter, we mechanically transfer a graphene-hBN heterostructure onto the prepatterned electrodes. We show that room temperature spin transport in single-, bi-, and trilayer graphene devices exhibit nanosecond spin lifetimes with spin diffusion lengths reaching 10 ?m combined with carrier mobilities exceeding 20?000 cm(2)/(V s). PMID:25291305

Drögeler, Marc; Volmer, Frank; Wolter, Maik; Terrés, Bernat; Watanabe, Kenji; Taniguchi, Takashi; Güntherodt, Gernot; Stampfer, Christoph; Beschoten, Bernd

2014-11-12

172

Circuit-quantum electrodynamics with direct magnetic coupling to single-atom spin qubits in isotopically enriched 28Si  

NASA Astrophysics Data System (ADS)

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 28Si 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.

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

2014-08-01

173

Electrostatic spin control in multi-barrier nanowires  

NASA Astrophysics Data System (ADS)

We demonstrate that a consistent breakdown of the standard even-odd filling scheme in the Coulomb blockade regime can be easily obtained in a quantum dot containing two wells strongly coupled by a very transparent barrier. By exploiting a multi-gate configuration, we prove that a partial filling of nearly degenerate orbitals can be controlled electrostatically. Singlet-triplet spin transitions are demonstrated by low-temperature magneto-transport measurements.

Rossella, Francesco; Ercolani, Daniele; Sorba, Lucia; Beltram, Fabio; Roddaro, Stefano

2014-10-01

174

Controllable spin-charge transport in strained graphene nanoribbon devices  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

175

Electrical control of flying spin precession in chiral 1D edge states  

SciTech Connect

Electrical control and detection of spin precession are experimentally demonstrated by using spin-resolved edge states in the integer quantum Hall regime. Spin precession is triggered at a corner of a biased metal gate, where electron orbital motion makes a sharp turn leading to a nonadiabatic change in the effective magnetic field via spin-orbit interaction. The phase of precession is controlled by the group velocity of edge-state electrons tuned by gate bias voltage: Spin-FET-like coherent control of spin precession is thus realized by all-electrical means.

Nakajima, Takashi; Komiyama, Susumu [Department of Basic Science, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902 (Japan); Lin, Kuan-Ting [Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China)

2013-12-04

176

Comparison of Magnetization Tunneling in the Giant-Spin and Multi-Spin Descriptions of Single-Molecule Magnets  

NASA Astrophysics Data System (ADS)

We perform a mapping of the spectrum obtained for a triangular Mn3 single-molecule magnet (SMM) with idealized C3 symmetry via exact diagonalization of a multi-spin (MS) Hamiltonian onto that of a giant-spin (GS) model which assumes strong ferromagnetic coupling and a spin S = 6 ground state. Magnetic hysteresis measurements on this Mn3 SMM reveal clear evidence that the steps in magnetization due to magnetization tunneling obey the expected quantum mechanical selection rules [J. Henderson et al., Phys. Rev. Lett. 103, 017202 (2009)]. High-frequency EPR and magnetization data are first fit to the MS model. The tunnel splittings obtained via the two models are then compared in order to find a relationship between the sixth order transverse anisotropy term B6^6 in GS model and the exchange constant J coupling the Mn^III ions in the MS model. We also find that the fourth order transverse term B4^3 in the GS model is related to the orientation of JahnTeller axes of Mn^III ions, as well as J

Liu, Junjie; Del Barco, Enrique; Hill, Stephen

2010-03-01

177

A photon-assisted single-spin quantum-dot heat engine  

NASA Astrophysics Data System (ADS)

We propose a time-dependent heat engine based on a single quantum dot (QD) sandwiched between two metallic electrodes. An external time-dependent field is applied on the single QD, which induces the periodic oscillation of energy levels inside the QD. Thus, the multiple transport channels are opened, resulting in the occurrence of the photon-assisted work regions for the heat engine. When an external magnetic field is presented, a photon-assisted single-spin heat engine is achieved. In some energy regions, the heat engine can be used to produce the single-spin current. Our results presented here indicate a way to fabricate the photon-assisted QD thermospin devices.

Yang, X. F.; Liu, Y. S.

2014-11-01

178

Electron exchange coupling for single-donor solid-state spin qubits C. J. Wellard,1  

E-print Network

into the silicon substrate using an 15 keV ion beam in the so-called ``top down'' fabrication scheme for a KaneElectron exchange coupling for single-donor solid-state spin qubits C. J. Wellard,1 L. C. L conduction band minima has been shown to lead to oscillations in the exchange energy between neighboring

Goan, Hsi-Sheng

179

Electrically driven single-electron spin resonance in a slanting Zeeman field  

E-print Network

LETTERS Electrically driven single-electron spin resonance in a slanting Zeeman field M. PIORO for Nano Quantum Information Electronics, University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505, Japan *e are confined and spatially separated from each other in a gate-defined double quantum dot18 (Fig. 1a). The a.c

Loss, Daniel

180

Coherent population trapping of an electron spin in a single negatively charged  

E-print Network

,8 , slow light9 , quantum information storage10 and quantum repeaters11,12 . A critical condition proposed as a qubit for quantum computing owing to its long coherence time compared with fast opticalLETTERS Coherent population trapping of an electron spin in a single negatively charged quantum dot

Loss, Daniel

181

Ultrafast coherent control of Spin- and magnetization dynamics  

NASA Astrophysics Data System (ADS)

The manipulating of the electron spin is not only relevant for magnetic storage but may also lead to the development of novel electronic devices with new characteristics (so-called spintronics). Therefore, the investigations of the physical mechanisms underlying the manipulation of electron spin in ferromagnets, semiconductors and hybrid ferromagnet/semiconductor structures constitute at present an exciting area of research. Due to the fact that in antiferromagnets no angular momentum is associated with the order parameter, spin dynamics in these materials is intrinsically much faster than in ferromagnets, expanding the area of spin-dynamics even more ^[1]. Femto-second laser excitation opens the way to excite magnetic systems on a time scale much shorter than fundamental time scales such as spin-lattice relaxation or precession times. This has already lead to surprising and exciting results like changes in magnetization on a sub-picoscond time scale ^[2]. Fs laser pulses can also be used to generate short magnetic field pulses, that allow coherent control of the magnetization dynamics ^[3] . Recent progress in this area will be discussed, demonstrating in particular the use of time resolved magneto-optical methods to investigate the static and dynamic properties of magnetically ordered structures and the possibility of direct spin manipulation with optical fields^[4,5]. [1] A. V. Kimel, A. Kirilyuk, A. Tsvetkov, R. V. Pisarev, and Th. Rasing, Nature 429 850 (2004). [2] Spin Dynamics in Confined Magnetic Structures I-II, edited by B. Hillebrands and K. Ounadjela (Springer-Verlag, Berlin, 2002-2003). [3] Th. Gerrits, H. A. M. van den Berg, J. Hohlfeld, L. Bär, and Th. Rasing, Nature 418, 509 (2002). [4] A. Kimel, A. Kirilyuk, P.A. Usachev, R.V. Pisarev, A.M. Balbashov and Th. Rasing, Nature 435, 655 (2005) [5] F. Hansteen, A.V. Kimel, A. Kirilyuk and Th. Rasing, PRL 95, 047402-1 (2005). Acknowledgements This work was partially supported by the European IST network SPINOSA, the RTN network DYNAMICS, the Russian Foundation for Basic Research (RFBR), Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) as well as Stichting voor Fundamenteel Onderzoek der Materie (FOM).

Rasing, Theo

2006-03-01

182

Spin Splitting of Single 0D Impurity States in Semiconductor Heterostructure Quantum Wells  

Microsoft Academic Search

Zeeman splitting of the ground state of single impurities in the quantum well of a resonant tunneling heterostructure is reported. We determine the absolute magnitude of the effective magnetic spin splitting factor g*? for a single impurity in a 44 Å Al0.27Ga0.73As\\/GaAs\\/Al0.27Ga0.73As quantum well to be 0.28 +\\/- 0.02. This system also allows for independent measurement of the electron tunneling

M. R. Deshpande; J. W. Sleight; M. A. Reed; R. G. Wheeler; R. J. Matyi

1996-01-01

183

Spin Splitting of Single 0D Impurity States in Semiconductor Heterostructure Quantum Wells  

Microsoft Academic Search

Zeeman splitting of the ground state of single impurities in the quantum well of a resonant tunneling heterostructure is reported. We determine the absolute magnitude of the effective magnetic spin splitting factor g p ' for a single impurity in a 44 ÅA l 0.27Ga0.73AsyGaAsyAl0.27Ga0.73As quantum well to be 0.28 6 0.02. This system also allows for independent measurement of

M. R. Deshpande; J. W. Sleight; M. A. Reed; R. G. Wheeler; R. J. Matyi

1996-01-01

184

Interactions between SAS-C spacecraft nutations and spin control system  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

185

Dynamics and Control of a Quasi-1D Spin System  

E-print Network

We study experimentally a system comprised of linear chains of spin-1/2 nuclei that provides a test-bed for multi-body dynamics and quantum information processing. This system is a paradigm for a new class of quantum information devices that can perform particular tasks even without universal control of the whole quantum system. We investigate the extent of control achievable on the system with current experimental apparatus and methods to gain information on the system state, when full tomography is not possible and in any case highly inefficient.

Paola Cappellaro; Chandrasekhar Ramanathan; David G. Cory

2007-06-04

186

Dynamics of a Mn spin coupled to a single hole confined in a quantum dot  

NASA Astrophysics Data System (ADS)

Using the emission of the positively charged exciton as a probe, we analyze the dynamics of the optical pumping and the dynamics of the relaxation of a Mn spin exchange coupled with a confined hole spin in a II-VI semiconductor quantum dot. The hole-Mn spin can be efficiently initialized in a few tens of ns under optical injection of spin-polarized carriers. We show that this optical pumping process and its dynamics are controlled by electron-Mn flip-flops within the positively charged exciton-Mn complex. The pumping mechanism and its magnetic field dependence are theoretically described by a model including the dynamics of the electron-Mn complex in the excited state and the dynamics of the hole-Mn complex in the ground state of the positively charged quantum dot. We measure at zero magnetic field a spin-relaxation time of the hole-Mn spin in the ?s range or shorter. This hole-Mn spin relaxation is induced by the presence of valence-band mixing in self-assembled quantum dots.

Varghese, B.; Boukari, H.; Besombes, L.

2014-09-01

187

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

SciTech Connect

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.

Wagner, Andreas; Bruder, Christoph; Demler, Eugene [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States)

2011-12-15

188

User guide for single-building controllers  

SciTech Connect

A tremendous opportunity exists for the Navy to save energy used for heating and cooling buildings by using single-building controllers. Thompson Laboratory at China Lake NWC, California is one example. A single-building controller was installed with pre- and post-metering. A simple pulley change on the air-handling units resulted in a 40% energy savings. The single-building controller contributed another 40% savings, resulting in a payback of 6 months with a total cost of $20,000.00. There was no impact on comfort and all building ventilation requirements were met. A few prerequisites are necessary for effective installation of single-building controllers. One person needs to be excited about energy conservation and willing to work. That person needs the support of the commander and active cooperation from the building occupants. Buildings that are suitable for single-building controllers are those that consume at least $10,000.00 of energy a year for heating and cooling, are not occupied on a 24-hour basis, and do not have temperature-sensitive equipment or material inside the building. Excellent candidate buildings are administration and office buildings.

Canfield, K.

1987-04-01

189

Spin control and manipulation in (111) GaAs quantum wells  

NASA Astrophysics Data System (ADS)

The control of spin dephasing is an essential requirement for quantum information processing using electron spins in IIIV semiconductors. GaAs quantum wells grown along the non-conventional [111] crystallographic direction are particularly interesting for spintronics due to the long spin lifetimes, which can be electrically controlled. Here, we show electron spin dynamics in (111) quantum wells by combining spatially-resolved with time-resolved photoluminescence measurements. The latter allows us to experimentally demonstrate the field induced enhancement of the spin lifetime as well as the transport of spin over several micrometers along the quantum well plane.

Hernández-Mínguez, A.; Biermann, K.; Hey, R.; Santos, P. V.

2014-08-01

190

Coherent control of hyperfine-coupled electron and nuclear spins for quantum information processing  

E-print Network

Coupled electron-nuclear spins are promising physical systems for quantum information processing: By combining the long coherence times of the nuclear spins with the ability to initialize, control, and measure the electron ...

Yang, Jamie Chiaming

2008-01-01

191

Twist-three Fragmentation Function Contribution to the Single Spin Asymmetry in pp Collisions  

SciTech Connect

We study the twist-three fragmentation function contribution to the single transverse spin asymmetries in inclusive hadron production in pp collisions, pp->h+X. In particular, we evaluate the so-called derivative contribution which dominates the spin asymmetry in the forward direction of the polarized proton. With certain parametrizations for the twist-three fragmentation function, we estimate its contribution to the asymmetry of pi0 production at RHIC energy. We find that the contribution is sizable and might be responsible for the big difference between the asymmetries in eta and pi0 productions observed by the STAR collaboration at RHIC.

Kang, Zhong-Bo; Yuan, Feng; Zhou, Jian

2010-01-29

192

Large-Spin and Large-Winding Expansions of Giant Magnons and Single Spikes  

E-print Network

We generalize the method of our recent paper on 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 RxS2 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.

Emmanuel Floratos; Georgios Linardopoulos

2014-06-03

193

Dynamics and control of a single-line maneuverable kite  

NASA Astrophysics Data System (ADS)

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.

Donnelly, Christopher Joseph

194

Laser and Microwave Excitations of Rabi Oscillations of a Single Nitrogen-Vacancy Electron Spin in Diamond  

E-print Network

A collapse and revival shape of Rabi oscillations of a single Nitrogen-Vacancy (NV) center electron spin has been observed in diamond at room temperature. Because of hyperfine interaction between the host 14N nuclear spin and NV center electron spin, different orientation of the 14N nuclear spin leads to a triplet splitting of the transition between the ground ms=0 and excited states ms=1. Microwave can excite the three transitions equally to induce three independent nutations and the shape of Rabi oscillations is a combination of the three nutations. This result provides an innovative view of electron spin oscillations in diamond.

Chunyang Tang; Xin Hu; Xinyu Pan

2010-09-08

195

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

SciTech Connect

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

Wang, Meng [ORNL; Wang, X.C. [Beijing National Laboratory for Condensed Matter Physics/Chinese Academy of Scie; Abernathy, Douglas L [ORNL; Harriger, Leland W [ORNL; Luo, H.Q. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics; Zhao, Yang [ORNL; Lynn, J. W. [National Institute of Standards and Technology (NIST); Liu, Q.Q. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics; Jin, C.Q. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics; Fang, Chen [Purdue University; Hu, Jiangping [Purdue University and Chinese Academy of Sciences; Dai, Pengcheng [University of Tennessee, Knoxville (UTK)

2011-01-01

196

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

PubMed Central

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

Ban, Yue; Chen, Xi

2014-01-01

197

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

PubMed

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

Ban, Yue; Chen, Xi

2014-01-01

198

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

NASA Astrophysics Data System (ADS)

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.

Ban, Yue; Chen, Xi

2014-09-01

199

Ultrafast control of electron spin in a quantum dot using geometric phase  

NASA Astrophysics Data System (ADS)

We propose a scheme to perform arbitrary unitary operations on a single electron-spin qubit in a quantum dot. The design is solely based on the geometrical phase that the qubit state acquires after a cyclic evolution in the parameter space. The scheme is utilizing ultrafast linearly-chirped pulses providing adiabatic excitation of the qubit states and the geometric phase is fully controlled by the relative phase between pulses. The analytic expression of the evolution operator for the electron spin in a quantum dot, which provides a clear geometrical interpretation of the qubit dynamics is obtained. Using parameters of InGaN/GaN, GaN/AlN quantum dots we provide an estimate for the time scale of the qubit rotations and parameters of the external fields.

Malinovsky, V. S.; Rudin, S.

2012-12-01

200

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

NASA Astrophysics Data System (ADS)

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.

Nossa, Javier; Canali, Carlo

2013-03-01

201

Spin-wave excitations in superlattices self-assembled in multiferroic single crystals.  

PubMed

Spin-wave excitations revealed in the dynamically equilibrated one-dimensional superlattices formed due to phase separation and charge carrier self-organization in doped single crystals of Eu(0.8)Ce(0.2)Mn(2)O(5) and Tb(0.95)Bi(0.05)MnO(3) multiferroics are discussed. Similar excitations, but having lower intensities, were also observed in undoped RMn(2)O(5) (R=Eu, Er, Tb, Bi). This suggests that a charge transfer between manganese ions with different valences, which give rise to the superlattice formation, occurs in undoped multiferroics as well. The spin excitations observed in the native superlattices represent a set of homogeneous spin-wave resonances excited in individual superlattice layers. The positions of these resonances depend on the relation between the numbers of Mn(3+) and Mn(4+) ions, charge carrier concentrations, and barrier depths in the superlattice layers. It has been found that the spin-wave excitations observed in the frequency interval studied (30-50 GHz) form two spin-wave minibands with a gap between them. PMID:22872124

Sanina, V A; Golovenchits, E I; Zalesskii, V G

2012-08-29

202

Pinning Complex Networks by a Single Controller  

Microsoft Academic Search

In this paper, without assuming symmetry, irreducibility, or linearity of the couplings, we prove that a single controller can pin a coupled complex network to a homogenous solution. Sufficient conditions are presented to guarantee the convergence of the pinning process locally and globally. An effective approach to adapt the coupling strength is proposed. Several numerical simulations are given to verify

Tianping Chen; Xiwei Liu; Wenlian Lu

2007-01-01

203

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

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

204

Magnetoresistance in a lithography defined single constrained domain wall spin-valve  

NASA Astrophysics Data System (ADS)

We have measured domain wall magnetoresistance in a single lithographically constrained domain wall. An H-shaped Ni nanobridge was fabricated by e-beam lithography with the two sides being single magnetic domains showing independent magnetic switching. The connection between the sides constrains the domain wall when the sides line up antiparallel. The magnetoresistance curve clearly identifies the magnetic configurations that are expected from a spin-valvelike structure. The value of the magnetoresistance at room temperature is around 0.1% or 0.4 ?. This value is shown to be in agreement with a theoretical formulation based on spin accumulation. Micromagnetic simulations show that it is possible to reduce the size of the domain wall further by shortening the length of the bridge.

Wang, Yudong; de Groot, C. H.; Claudio-Gonzalez, D.; Fangohr, Hans

2010-12-01

205

Phase diagram of the mixed spin-2 and spin-5/2 Ising system with two different single-ion anisotropies  

NASA Astrophysics Data System (ADS)

We study the effect of two different single-ion anisotropies in the phase diagram and in the compensation temperature of mixed spin-2 and spin-5/2 Ising ferrimagnetic system. We employed the mean-field theory based on the Bogoliubov inequality for Gibbs free energy. We use the Landau expansion of free energy in the order parameter to describe the phase diagram. In the temperature versus single-ion anisotropy plane the phase diagram displays tricritical behavior. The critical and compensation temperatures increase with increasing values of the single-ion anisotropies.

da Cruz Filho, J. S.; Godoy, M.; de Arruda, A. S.

2013-12-01

206

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

E-print Network

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

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

2014-10-02

207

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

E-print Network

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

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

2014-01-01

208

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

209

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

PubMed Central

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

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

2012-01-01

210

Twofold spin reorientation and field-induced incomplete phase transition in single-crystal Dy0.5Pr0.5FeO3  

NASA Astrophysics Data System (ADS)

We report an intriguing twofold spin reorientation transition of type ?4(Gx,Ay,Fz)??1(Ax,Gy,Cz)??2(Fx,Cy,Gz) for the Fe3+ magnetic sublattice near spin reorientation temperatures TSR1˜77 K and TSR2˜45 K in a rare-earth orthoferrite Dy0.5Pr0.5FeO3 single crystal. Magnetic-field-induced incomplete spin-configuration transitions (?4??41??42 for H =20kOe and ?4??42 for H =40kOe) were observed by measurement of magnetization as a function of temperature. The spin reorientation temperature of a Dy0.5Pr0.5FeO3 single crystal can be controlled by changing the magnitude of the applied magnetic field. We also show that spin reorientation of the ?1??4 type between TSR2 and TSR1 can be induced by an applied magnetic field along the c axis. The origin of the intriguing magnetic behavior is ascribed to the anisotropic effective field whose strength is determined by the interactions with R3+(R =Dy,Pr) spins and can be modified by the external applied magnetic field. It provides deeper insight into the Fe3+-R3+ magnetic interaction which dominates the sophisticated magnetic phase transitions in the rare-earth orthoferrites.

Wu, Hailong; Cao, Shixun; Liu, Ming; Cao, Yiming; Kang, Baojuan; Zhang, Jincang; Ren, Wei

2014-10-01

211

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

NASA Astrophysics Data System (ADS)

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.

Mosshammer, Klemens; Brandes, Tobias

2014-10-01

212

A switchable controlled-NOT gate in a spin-chain NMR quantum computer  

Microsoft Academic Search

A method of switching a controlled-NOT gate in a solid-stae NMR quantum\\u000acomputer is presented. Qubits of I=1\\/2 nuclear spins are placed periodically\\u000aalong a quantum spin chain (1-D antiferromagnet) having a singlet ground state\\u000awith a finite spin gap to the lowest excited state caused by some quantum\\u000aeffect. Irradiation of a microwave tuned to the spin gap energy

Atsushi Goto; Tadashi Shimizu; Kenjiro Hashi; Hideaki Kitazawa

2002-01-01

213

Current-induced control of spin-wave attenuation.  

PubMed

The current-induced modification of the attenuation of a propagating spin wave in a magnetic nanowire is studied theoretically and numerically. The attenuation length of spin wave can increase when the spin waves and electrons move in the same direction. It is directly affected by the nonadiabaticity of the spin-transfer torque and thus can be used to estimate the nonadiabaticity. When the nonadiabatic spin torque is sufficiently large, the attenuation length becomes negative, resulting in the amplification of spin waves. PMID:19392477

Seo, Soo-Man; Lee, Kyung-Jin; Yang, Hyunsoo; Ono, Teruo

2009-04-10

214

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

SciTech Connect

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.

Leonard Gamberg, Zhong-Bo Kang

2011-01-01

215

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

NASA Astrophysics Data System (ADS)

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.

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

216

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

PubMed

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

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

217

Teleportation of Electronic Many-Qubit States Encoded in the Electron Spin of Quantum Dots via Single Photons  

E-print Network

Teleportation of Electronic Many-Qubit States Encoded in the Electron Spin of Quantum Dots via propose a teleportation scheme that relies only on single-photon measurements and Faraday rotation, for teleportation of many-qubit entangled states stored in the electron spins of a quantum dot system

Flatte, Michael E.

218

Analytical and micromagnetic modeling for detection of a single magnetic microbead or nanobead by spin valve sensors  

Microsoft Academic Search

We present a simple analytical model based on the Stoner-Wohlfarth model for the detection of a single magnetic microbead or nanobead by spin valve sensors. Two-dimensional micromagnetic simulations were also performed for the spin valve sensors. It is found that the analytical model fits well with the micromagnetic simulations in the case of the microbead, although it underestimates the effect

Guanxiong Li; Shan X. Wang

2003-01-01

219

THE JOURNAL OF CHEMICAL PHYSICS 141, 064104 (2014) Analytic derivative couplings for spin-flip configuration interaction singles  

E-print Network

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-flip configuration interaction singles and spin-flip time-dependent density functional theory Xing Zhang and John M

Herbert, John

220

Spin excitations in a single La2CuO4 layer.  

PubMed

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

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

2012-10-01

221

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

SciTech Connect

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.

Choudhary, Shashank, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Tejesh, Chiruvolu Mohan, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Regalla, Srinivasa Prakash, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Suresh, Kurra, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in [Department of Mechanical Engineering, BITS-Pilani, Hyderabad Campus, Shamirpet, Hyderabad, 500078, Andhra Pradesh (India)

2013-12-16

222

Magnetic control spin-polarization reversal in a hybrid ferromagnet/semiconductor spin filter  

NASA Astrophysics Data System (ADS)

Electron spin-polarization reversal is achieved in a hybrid ferromagnet/semiconductor spin filter by introducing the third magnetic barrier and a subtle variation of its strength, and the ground or the second resonance states could be reversed separately by changing its magnetization direction. This interesting feature is believed to be of significant importance for realizing the spin switches and multiple value logic devices.

Xu, Huaizhe; Wang, Liying; Wang, Hailong; Zhang, Shichao

2014-02-01

223

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

NASA Astrophysics Data System (ADS)

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 [1, 2]. Here we demonstrate a similar control over a nanoscale ensemble of spins using the mechanical readout of magnetic resonance force microscopy (MRFM) [3]. We employ the exceptional sensitivity of MRFM to perform real-time measurement and control of an ensemble containing 10^5 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. 1. Vink, I. T. et al. Nature Phys. 5, 764 (2009). 2. Latta, C. et al. Nature Phys. 5, 758 (2009). 3. Budakian, R. et al. Science 307, 408 (2005).

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

2013-03-01

224

Single spin asymmetries of inclusive hadrons produced in electron scattering from a transversely polarized [superscript 3]He target  

E-print Network

We report the first measurement of target single spin asymmetries (A[subscript N]) in the inclusive hadron production reaction, e + [superscript 3]He[superscript ?] ? h + X, using a transversely polarized [superscript 3]He ...

Allada, Kalyan C.

225

Kerr rotation studies of single electron spin dynamics in a quantum dot  

NASA Astrophysics Data System (ADS)

Kerr rotation measurements are used to directly and non-destructively probe the dynamics of a single electron spin in a charge-tunable quantum dot. The dot is formed by interface fluctuations of a GaAs quantum well and embedded in a vertical optical cavity. Using Hanle techniques, we perform single electron Kerr rotation measurements at T=10K in order to monitor the depolarization of an optically pumped electron spin within an applied transverse magnetic field. This reveals information about the time averaged transverse spin lifetime, T2^*. At gate voltages for which the charging rate of the dot is relatively low, the results yield a T2^* in agreement with values expected from the hyperfine interaction in these materials. In contrast, at larger charging rates, we find that T2^* is strongly reduced, indicating the importance of additional decoherence mechanisms in that regime. J. Berezovsky, M. H. Mikkelsen, O. Gywat, N. G. Stoltz, L. A. Coldren, and D. D. Awschalom,Science Express, 9 November 2006, (10.1126/science.1133862).

Mikkelsen, M. H.; Berezovsky, J.; Gywat, O.; Stoltz, N. G.; Coldren, L. A.; Awschalom, D. D.

2007-03-01

226

Large-gap quantum spin Hall insulator in single layer bismuth monobromide Bi4Br4.  

PubMed

Quantum spin Hall (QSH) insulators have gapless topological edge states inside the bulk band gap, which can serve as dissipationless spin current channels. The major challenge currently is to find suitable materials for this topological state. Here, we predict a new large-gap QSH insulator with bulk direct band gap of ? 0.18 eV, in single-layer Bi4Br4, which could be exfoliated from its three-dimensional bulk material due to the weakly bonded layered structure. The band gap of single-layer Bi4Br4 is tunable via strain engineering, and the QSH phase is robust against external strain. Moreover, because this material consists of special one-dimensional molecular chain as its basic building block, the single layer Bi4Br4 could be torn to ribbons with clean and atomically sharp edges. These nanoribbons, which have single-Dirac-cone edge states crossing the bulk band gap, are ideal wires for dissipationless transport. Our work thus provides a new promising material for experimental studies and practical applications of the QSH effect. PMID:25058154

Zhou, Jin-Jian; Feng, Wanxiang; Liu, Cheng-Cheng; Guan, Shan; Yao, Yugui

2014-08-13

227

Transverse Single Spin Asymmetry Measurement with J/Psi in Polarized p+p Collisions at RHIC  

E-print Network

The PHENIX experiment has measured transverse single spin asymmetry of J/$\\Psi$ in polarized p+p collisions at forward rapidity at $\\sqrt{s}=200$ GeV. The data were collected from year 2006 run of RHIC with average beam polarization of 56%. At RHIC energy, heavy quark production is dominated by gluon gluon interaction. Therefore, the transverse single spin asymmetry in J/$\\Psi$ production can provide a clean measurement of the gluon Sivers distribution function.

Han Liu

2006-12-13

228

Hydrodynamic limit for conservative spin systems with super-quadratic, partially inhomogeneous single-site potential  

E-print Network

We consider an interacting unbounded spin system, with conservation of the mean spin. We derive quantitative rates of convergence to the hydrodynamic limit provided the single-site potential is a bounded perturbation of a strictly convex function with polynomial growth, and with an additional random inhomogeneous linear term. This additional linear term models the impact of a random chemical potential. The argument adapts the two-scale approach of Grunewald, Otto, Villani and Westdickenberg from the quadratic to the general case. The main ingredient is the derivation of a covariance estimate that is uniform in the system size. We also show that this covariance estimate can be used to change the iterative argument of [MO] for deducing the optimal scaling LSI for the canonical ensemble into a two-scale argument in the sense of [GOVW]. We also prove the LSI for canonical ensembles with an inhomogeneous linear term.

Max Fathi; Georg Menz

2014-05-13

229

Spin switching and magnetization reversal in single-crystal NdFeO3  

NASA Astrophysics Data System (ADS)

We report an experimental and computational study of single-crystal NdFeO3, which features two inequivalent magnetic sublattices, namely, Fe and Nd sublattices that are coupled in an antiparallel fashion. This paper reveals that a strong interaction between 3d and 4f electrons of the two sublattices along with a spin-lattice coupling drives an extremely interesting magnetic state that is highly sensitive to the orientation and history of weak magnetic field. The following phenomena are particularly remarkable: (1) sharply contrasting magnetization M(T) along the a and c axes; (2) a first-order spin switching along the a axis below 29 K when the system is zero-field-cooled; and (3) a progressive magnetization reversal when the system is field-cooled. The intriguing magnetic behavior is captured in our first-principles density functional theory calculations.

Yuan, S. J.; Ren, W.; Hong, F.; Wang, Y. B.; Zhang, J. C.; Bellaiche, L.; Cao, S. X.; Cao, G.

2013-05-01

230

Using heat to control the sample spinning speed in MAS NMR.  

PubMed

A new approach using temperature to control the spinning speed of a sample rotor in magic-angle spinning NMR is presented. Instead of an electro-mechanical valve that regulates the flow of drive gas to control the spinning speed in traditional MAS NMR systems, we use a small heater wire located directly in the stator. The sample spinning speed is controlled very accurately with a surprisingly low heating power of 1 W. Results on a benchtop unit demonstrate the capability of the system. PMID:21820341

Mihaliuk, Eugene; Gullion, Terry

2011-10-01

231

High-resolution spectroscopy of single NV defects coupled with nearby 13C nuclear spins in diamond  

NASA Astrophysics Data System (ADS)

We report a systematic study of the hyperfine interaction between the electron spin of a single nitrogen-vacancy (NV) defect in diamond and nearby 13C nuclear spins, by using pulsed electron-spin resonance spectroscopy. We isolate a set of discrete values of the hyperfine coupling strength ranging from 14 MHz to 400 kHz and corresponding to 13C nuclear spins placed at different lattice sites of the diamond matrix. For each lattice site, the hyperfine interaction is further investigated through nuclear-spin polarization measurements and by studying the magnetic field dependence of the hyperfine splitting. This work provides information that is relevant for the development of nuclear-spin-based quantum register in diamond.

Dréau, A.; Maze, J.-R.; Lesik, M.; Roch, J.-F.; Jacques, V.

2012-04-01

232

Phase Diagram of the mixed spin-2 and spin-5/2 Ising system with two different single-ion anisotropies  

NASA Astrophysics Data System (ADS)

In the last five decades the Ising model has been one of the most largely used to describe critical behavior of several systems in the nature. In particular, in the physics of the condensed matter it is important to describe critical behavior and other thermodynamics properties of a variety of physic systems (disordered system, spins glass, random field Ising model, etc.). Recently, several extensions have been made in the spin-1/2 Ising model to describe a wide variety of physic systems. For example, the models consisting of mixed spins of different magnitudes are interesting extensions, which are so-called mixed-spin Ising models. In this work we present a study of the effects of two single-ion anisotropies in the phase diagram and in the compensation temperatures of the mixed spin-2 and spin-5/2 Ising ferrimagnetic system. We employ the mean-field theory based on the Bogoliubov inequality for the Gibbs free energy, and the Landau expansion of the free energy in the order parameter to describe the phase diagrams. In the plane critical temperature versus single-ion anisotropie the phase diagram display behavior tricritical (second-order transition separated of the first-order transition lines by a tricritical point).

Cruz Filho, José.; Godoy, Mauricio; Arruda, Alberto

2012-02-01

233

All-optical sensing of a single-molecule electron spin  

E-print Network

We demonstrate an all-optical method for magnetic sensing of individual molecules in ambient conditions at room temperature. Our approach is based on shallow nitrogen-vacancy (NV) centers near the surface of a diamond crystal, which we use to detect single paramagnetic molecules covalently attached to the diamond surface. The manipulation and readout of the NV centers is all-optical and provides a sensitive probe of the magnetic field fluctuations stemming from the dynamics of the electronic spins of the attached molecules. As a specific example, we demonstrate detection of a single paramagnetic molecule containing a gadolinium (Gd$^{3+}$) ion. We confirm single-molecule resolution using optical fluorescence and atomic force microscopy to co-localize one NV center and one Gd$^{3+}$-containing molecule. Possible applications include nanoscale and in vivo magnetic spectroscopy and imaging of individual molecules.

Sushkov, A O; Lovchinsky, I; Kubo, M; Lo, P K; Bennett, S D; Hunger, D; Akimov, A; Walsworth, R L; Park, H; Lukin, M D

2013-01-01

234

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

E-print Network

We test experimentally the quantum ``paradox'' proposed by Lucien Hardy in 1993 [Phys. Rev. Lett. 71, 1665 (1993)] 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 non-contextuality, 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.

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

2014-03-22

235

All-optical sensing of a single-molecule electron spin.  

PubMed

We demonstrate an all-optical method for magnetic sensing of individual molecules in ambient conditions at room temperature. Our approach is based on shallow nitrogen-vacancy (NV) centers near the surface of a diamond crystal, which we use to detect single paramagnetic molecules covalently attached to the diamond surface. The manipulation and readout of the NV centers is all-optical and provides a sensitive probe of the magnetic field fluctuations stemming from the dynamics of the electronic spins of the attached molecules. As a specific example, we demonstrate detection of a single paramagnetic molecule containing a gadolinium (Gd(3+)) ion. We confirm single-molecule resolution using optical fluorescence and atomic force microscopy to colocalize one NV center and one Gd(3+)-containing molecule. Possible applications include nanoscale and in vivo magnetic spectroscopy and imaging of individual molecules. PMID:25333198

Sushkov, A O; Chisholm, N; Lovchinsky, I; Kubo, M; Lo, P K; Bennett, S D; Hunger, D; Akimov, A; Walsworth, R L; Park, H; Lukin, M D

2014-11-12

236

All-optical sensing of a single-molecule electron spin  

E-print Network

We demonstrate an all-optical method for magnetic sensing of individual molecules in ambient conditions at room temperature. Our approach is based on shallow nitrogen-vacancy (NV) centers near the surface of a diamond crystal, which we use to detect single paramagnetic molecules covalently attached to the diamond surface. The manipulation and readout of the NV centers is all-optical and provides a sensitive probe of the magnetic field fluctuations stemming from the dynamics of the electronic spins of the attached molecules. As a specific example, we demonstrate detection of a single paramagnetic molecule containing a gadolinium (Gd$^{3+}$) ion. We confirm single-molecule resolution using optical fluorescence and atomic force microscopy to co-localize one NV center and one Gd$^{3+}$-containing molecule. Possible applications include nanoscale and in vivo magnetic spectroscopy and imaging of individual molecules.

A. O. Sushkov; N. Chisholm; I. Lovchinsky; M. Kubo; P. K. Lo; S. D. Bennett; D. Hunger; A. Akimov; R. L. Walsworth; H. Park; M. D. Lukin

2013-11-07

237

Polytype control of spin qubits in silicon carbide.  

PubMed

Crystal defects can confine isolated electronic spins and are promising candidates for solid-state quantum information. Alongside research focusing on nitrogen-vacancy centres in diamond, an alternative strategy seeks to identify new spin systems with an expanded set of technological capabilities, a materials-driven approach that could ultimately lead to 'designer' spins with tailored properties. Here we show that the 4H, 6H and 3C polytypes of SiC all host coherent and optically addressable defect spin states, including states in all three with room-temperature quantum coherence. The prevalence of this spin coherence shows that crystal polymorphism can be a degree of freedom for engineering spin qubits. Long spin coherence times allow us to use double electron-electron resonance to measure magnetic dipole interactions between spin ensembles in inequivalent lattice sites of the same crystal. Together with the distinct optical and spin transition energies of such inequivalent states, these interactions provide a route to dipole-coupled networks of separately addressable spins. PMID:23652007

Falk, Abram L; Buckley, Bob B; Calusine, Greg; Koehl, William F; Dobrovitski, Viatcheslav V; Politi, Alberto; Zorman, Christian A; Feng, Philip X-L; Awschalom, David D

2013-01-01

238

Polytype control of spin qubits in silicon carbide  

PubMed Central

Crystal defects can confine isolated electronic spins and are promising candidates for solid-state quantum information. Alongside research focusing on nitrogen-vacancy centres in diamond, an alternative strategy seeks to identify new spin systems with an expanded set of technological capabilities, a materials-driven approach that could ultimately lead to ‘designer’ spins with tailored properties. Here we show that the 4H, 6H and 3C polytypes of SiC all host coherent and optically addressable defect spin states, including states in all three with room-temperature quantum coherence. The prevalence of this spin coherence shows that crystal polymorphism can be a degree of freedom for engineering spin qubits. Long spin coherence times allow us to use double electron–electron resonance to measure magnetic dipole interactions between spin ensembles in inequivalent lattice sites of the same crystal. Together with the distinct optical and spin transition energies of such inequivalent states, these interactions provide a route to dipole-coupled networks of separately addressable spins. PMID:23652007

Falk, Abram L.; Buckley, Bob B.; Calusine, Greg; Koehl, William F.; Dobrovitski, Viatcheslav V.; Politi, Alberto; Zorman, Christian A.; Feng, Philip X.-L.; Awschalom, David D.

2013-01-01

239

Analytic derivative couplings for spin-flip configuration interaction singles and spin-flip time-dependent density functional theory.  

PubMed

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 H3 near its D(3h) geometry demonstrates that correct topology is obtained in the vicinity of a conical intersection involving a degenerate ground state. PMID:25134548

Zhang, Xing; Herbert, John M

2014-08-14

240

Ultrafast optical control of electron spins in quantum wells and quantum dots  

NASA Astrophysics Data System (ADS)

Using two-color time-resolved Faraday rotation and ellipticity, we demonstrate ultrafast optical control of electron spins in GaAs quantum wells and InAs quantum dots. In quantum wells, a magnetic-field induced electron spin polarization is manipulated by off-resonant pulses. By measuring the amplitude and phase of the spin polarization as a function of pulse detuning, we observe the two competing optical processes: real excitation, which generates a spin polarization through excitation of electron-hole pairs; and virtual excitation, which can manipulate a spin polarization through a stimulated Raman process without exciting electron-hole pairs. In InAs quantum dots, the spin coherence time is much longer, so that the effect of many repetitions of the pump pulses is important. Through real excitation, the pulse train efficiently polarizes electron spins that precess at multiples of the laser repetition frequency, leading to a "mode-locking" phenomenon. Through virtual excitation, the spins can be partially rotated toward the magnetic field direction, leading to a sensitive dependence of the spin orientation on the precession frequency and detuning. The electron spin dynamics strongly influence the nuclear spin dynamics as well, leading to directional control of the nuclear polarization distribution.

Carter, Samuel G.; Economou, Sophia E.; Shabaev, Andrew; Kennedy, Thomas A.; Bracker, Allan S.; Reinecke, Thomas L.; Chen, Zhigang; Cundiff, Steven T.

2010-02-01

241

Dual-channel lock-in magnetometer with a single spin in diamond  

E-print Network

We present an experimental method to perform dual-channel lock-in magnetometry of time-dependent magnetic fields using a single spin associated with a nitrogen-vacancy (NV) color center in diamond. We incorporate multi-pulse quantum sensing sequences with phase estimation algorithms to achieve linearized field readout and constant, nearly decoherence-limited sensitivity over a wide dynamic range. Furthermore, we demonstrate unambiguous reconstruction of the amplitude and phase of the magnetic field. We show that our technique can be applied to measure random phase jumps in the magnetic field, as well as phase-sensitive readout of the frequency.

N. M. Nusran; M. V. Gurudev Dutt

2013-09-07

242

Nanoscale magnetic field mapping with a single spin scanning probe magnetometer  

SciTech Connect

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.

Rondin, L.; Tetienne, J.-P.; Spinicelli, P.; Roch, J.-F.; Jacques, V. [Laboratoire de Photonique Quantique et Moleculaire, Ecole Normale Superieure de Cachan and CNRS UMR 8537, 94235 Cachan Cedex (France); Dal Savio, C.; Karrai, K. [Attocube systems AG, Koeniginstrasse 11A RGB, Munich 80539 (Germany); Dantelle, G. [Laboratoire de Physique de la Matiere Condensee, Ecole Polytechnique and CNRS UMR 7643, 91128 Palaiseau (France); Thiaville, A.; Rohart, S. [Laboratoire de Physique des Solides, Universite Paris-Sud and CNRS UMR 8502, 91405 Orsay (France)

2012-04-09

243

Spin projection of single-determinant wavefunctions. [application to hydrocarbon radicals and ions  

NASA Technical Reports Server (NTRS)

The components of the one- and two-particle density matrices resulting from spin projection of a single-determinant wave function are rederived by the method of expansion in terms of the natural orbitals of charge density, and the results are found to diverge from those given by Harriman and Sando for the two-particle case. The theory is generalized to include molecules with unequal numbers of electrons and basis orbitals and is applied to a number of organic molecules and ions. The correctness and internal consistency of the results argue in favor of the modification described.

Phillips, D. H.; Schug, J. C.

1974-01-01

244

PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP ENTITLED ''SINGLE SPIN ASYMMETRIES'' (VOLUME 75)  

SciTech Connect

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.

YUAN, F.; VOGELSANG, W.

2005-06-01

245

Single-Spin Asymmetries for Small-Angle Pion Production in High-Energy Hadron Collisions  

E-print Network

Within the framework of a simple model, we study single-spin asymmetries for pion production in hadron-hadron collisions at high-energies with one hadron polarised. The asymmetries are generated via a mechanism of final (initial) state interactions. For peripheral kinematics, when the pion belongs to the fragmentation region of the polarised proton, we find non-zero asymmetries in the high-energy limit. Numerical results and comparision with existing experimental data are presented. We also discuss the relationship with odderon exchange phenomenology.

Ahmedov, A; Kuraev, E A; Ratcliffe, P G; Ahmedov, Azad; Akushevich, Igor V.; Kuraev, Eduard A.; Ratcliffe, Philip G.

1999-01-01

246

Nanoscale magnetic field mapping with a single spin scanning probe magnetometer  

NASA Astrophysics Data System (ADS)

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.

Rondin, L.; Tetienne, J.-P.; Spinicelli, P.; Dal Savio, C.; Karrai, K.; Dantelle, G.; Thiaville, A.; Rohart, S.; Roch, J.-F.; Jacques, V.

2012-04-01

247

Evolution of twist-3 multi-parton correlation functions relevant to single transverse-spin asymmetry  

E-print Network

We constructed two sets of twist-3 correlation functions that are responsible for generating the novel single transverse-spin asymmetry in the QCD collinear factorization approach. We derive evolution equations for these universal three-parton correlation functions. We calculate evolution kernels relevant to the gluonic pole contributions to the asymmetry at the order of $\\alpha_s$. We find that all evolution kernels are infrared safe as they should be and have a lot in common to the DGLAP evolution kernels of unpolarized parton distributions. By solving the evolution equations, we explicitly demonstrate the factorization scale dependence of these twist-3 correlation functions.

Zhong-Bo Kang; Jian-Wei Qiu

2008-11-19

248

Multiferroicity in spin ice Ho2Ti2O7: An investigation on single crystals  

NASA Astrophysics Data System (ADS)

The single crystals of rare-earth titanate pyrochlore compound Ho2Ti2O7 are grown and their multiferroicity along the [110] and [111] directions is investigated. The ferroelectricity below ˜28 K, with a polarization of ˜2.50 ?C/m2 along the ?111? direction at 2 K, qualitatively fitting with the theoretical scenario proposed by Khomskii (Nat. Commun. 3, 904 (2012)), is revealed. The magnetoelectric responses along both the [110] and [111] directions are observed, but different underlying mechanisms associated with the specific spin configurations are suggested.

Liu, D.; Lin, L.; Liu, M. F.; Yan, Z. B.; Dong, S.; Liu, J.-M.

2013-05-01

249

Electric control of spin in monolayer WSe2 field effect transistors  

NASA Astrophysics Data System (ADS)

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\\prime 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.

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

2014-10-01

250

Electric control of spin in monolayer WSe2 field effect transistors.  

PubMed

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 [Formula: see text] 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 [Formula: see text] in the FET is labelled by both the valley index and spin index, realizing valleytronics and spintronics in the same device. PMID:25287881

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

2014-10-31

251

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)

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.

Stough, H. Paul, III; Dicarlo, Daniel J.; Patton, James M., Jr.

1987-01-01

252

Imaging of Heterogeneous Materials with a Turbo Spin Echo Single-Point Imaging Technique  

NASA Astrophysics Data System (ADS)

A magnetic resonance imaging method is presented for imaging of heterogeneous broad linewidth materials. This method allows for distortionless relaxation weighted imaging by obtaining multiple phase encoded k-space data points with each RF excitation pulse train. The use of this method, turbo spin echo single-point imaging-(turboSPI), leads to decreased imaging times compared to traditional constant-time imaging techniques, as well as the ability to introduce spin-spin relaxation contrast through the use of longer effective echo times. Imaging times in turboSPI are further decreased through the use of low flip angle steady-state excitation. Two-dimensional images of paramagnetic doped agarose phantoms were obtained, demonstrating the contrast and resolution characteristics of the sequence, and a method for both amplitude and phase deconvolution was demonstrated for use in high-resolution turboSPI imaging. Three-dimensional images of a partially water-saturated porous volcanic aggregate ( T2L ? 200 ms, ?? 1/2 ? 2500 Hz) contained in a hardened white Portland cement matrix ( T2L ? 0.5 ms, ?? 1/2 ? 2500 Hz) and a water-saturated quartz sand ( T2 ? 300 ms, T2* ? 800 ?s) are shown.

Beyea, Steven D.; Balcom, Bruce J.; Mastikhin, Igor V.; Bremner, Theodore W.; Armstrong, Robin L.; Grattan-Bellew, Patrick E.

2000-06-01

253

Spin-controlled superconductivity and tunable triplet correlations in graphene nanostructures.  

PubMed

We study graphene ferromagnet/superconductor/ferromagnet (F/S/F) nanostructures via a microscopic self-consistent Dirac Bogoliubov-de Gennes formalism. We show that as a result of proximity effects, experimentally accessible spin switching phenomena can occur as one tunes the Fermi level ?F of the F regions or varies the angle ? between exchange field orientations. Superconductivity can then be switched on and off by varying either ? or ?F (a spin-controlled superconducting graphene switch). The induced equal-spin triplet correlations in S can be controlled by tuning ?F, effectively making a graphene based two-dimensional spin-triplet valve. PMID:23931389

Halterman, Klaus; Valls, Oriol T; Alidoust, Mohammad

2013-07-26

254

Experimental verification of the commutation relation for Pauli spin operators using single-photon quantum interference  

E-print Network

We report experimental verification of the commutation relation for Pauli spin operators using quantum interference of the single-photon polarization state. By superposing the quantum operations $\\sigma_z \\sigma_x$ and $\\sigma_x \\sigma_z$ on a single-photon polarization state, we have experimentally implemented the commutator, $[\\sigma_{z}, \\sigma_{x}]$, and the anticommutator, $\\{\\sigma_{z}, \\sigma_{x}\\}$, and have demonstrated the relative phase factor of $\\pi$ between $\\sigma_z \\sigma_x$ and $\\sigma_x \\sigma_z$ operations. The experimental quantum operation corresponding to the commutator, $[\\sigma_{z}, \\sigma_{x}]=k\\sigma_y$, showed process fidelity of 0.94 compared to the ideal $\\sigma_y$ operation and $|k|$ is determined to be $2.12\\pm0.18$.

Yong-Su Kim; Hyang-Tag Lim; Young-Sik Ra; Yoon-Ho Kim

2010-02-17

255

Elliptic functions and efficient control of Ising spin chainswith unequal couplings  

Microsoft Academic Search

In this article, we study optimal control of dynamics in a linear chain of three spin 1\\/2, weakly coupled with unequal Ising couplings. We address the problem of time-optimal synthesis of multiple spin quantum coherences. We derive time-optimal pulse sequence for creating a desired spin order by computing geodesics on a sphere under a special metric. The solution to the

Haidong Yuan; Robert Zeier; Navin Khaneja

256

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

PubMed

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

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

2014-01-01

257

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

NASA Astrophysics Data System (ADS)

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 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.

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

2014-04-01

258

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

259

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

NASA Astrophysics Data System (ADS)

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.

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

2010-10-01

260

Noise-compensating pulses for electrostatically controlled silicon spin qubits  

NASA Astrophysics Data System (ADS)

We study the performance of supcode—a family of dynamically correcting pulses designed to cancel simultaneously both Overhauser and charge noise for singlet-triplet spin qubits—adapted to silicon devices with electrostatic control. We consider both natural Si and isotope-enriched Si systems, and in each case we investigate the behavior of individual gates under static noise and perform randomized benchmarking to obtain the average gate error under realistic 1/f noise. We find that in most cases supcode pulses offer roughly an order of magnitude reduction in gate error, and especially in the case of isotope-enriched Si, supcode yields gate operations of very high fidelity. We also develop a version of supcode that cancels the charge noise only, "?J-supcode," which is particularly beneficial for isotope-enriched Si devices where charge noise dominates Overhauser noise, offering a level of error reduction comparable to the original supcode while yielding gate times that are 30%-50% shorter. Our results show that the supcode noise-compensating pulses provide a fast, simple, and effective approach to error suppression, bringing gate errors well below the quantum error correction threshold in principle.

Wang, Xin; Calderon-Vargas, F. A.; Rana, Muhed S.; Kestner, J. P.; Barnes, Edwin; Das Sarma, S.

2014-10-01

261

Controlling spin-wave propagation with Oersted fields  

NASA Astrophysics Data System (ADS)

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.footnotetextK. Vogt, H. Schultheiss, S. Jain, J.E. Pearson, A. Hoffmann, S.D. Bader, and B. Hillebrands, Appl. Phys. Lett. 101, 042410 (2012) We have modeled the current generated magnetic fields with a finite element code and calculated the magnetic response using micro magnetic simulations.

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

2013-03-01

262

Measurement of single- and double-spin asymmetries in deep inelastic pion electroproduction with a longitudinally polarized target.  

PubMed

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 Jefferson Lab (JLab). Modulations of single spin asymmetries over the azimuthal angle between lepton scattering and hadron production planes ? have been measured over a wide kinematic range in Bjorken x and virtual photon squared four-momentum Q2. A significant nonzero sin2? single spin asymmetry was observed for the first time indicating strong spin-orbit correlations for transversely polarized quarks in the longitudinally polarized proton. PMID:21231647

Avakian, H; Bosted, P; Burkert, V D; 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; De Vita, R; De Sanctis, 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, R; Forest, T A; Fradi, A; Gabrielyan, M Y; Gavalian, G; Gevorgyan, N; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Gohn, W; Gothe, R W; Griffioen, K A; Guidal, 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, P; 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; Martinez, D; 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; Pereira, S Anefalos; Perrin, Y; Pisano, S; Pogorelko, O; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Raue, B A; Ricco, G; Ripani, M; Rosner, G; Rossi, P; Sabatié, F; Saini, M S; Salamanca, J; Salgado, C; Schumacher, R A; Seder, E; Seraydaryan, H; Sharabian, Y G; Sober, D I; Sokhan, D; Stepanyan, S S; Stepanyan, S; Stoler, P; Strauch, S; Suleiman, R; Taiuti, M; Tedeschi, D J; Tkachenko, S; Ungaro, M; Vernarsky, B; Vineyard, M F; Voutier, E; Watts, D P; Weinstein, L B; Weygand, D P; Wood, M H; Zhang, J; Zhao, B; Zhao, Z W

2010-12-31

263

Single spin asymmetry AN in polarized proton-proton elastic scattering at ?{s}=200 GeV  

NASA Astrophysics Data System (ADS)

We report a high precision measurement of the transverse single spin asymmetry AN at the center of mass energy ?{s}=200 GeV in elastic proton-proton scattering by the STAR experiment at RHIC. The AN was measured in the four-momentum transfer squared t range 0.003?|t|?0.035 (, the region of a significant interference between the electromagnetic and hadronic scattering amplitudes. The measured values of AN and its t-dependence are consistent with a vanishing hadronic spin-flip amplitude, thus providing strong constraints on the ratio of the single spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated by the Pomeron amplitude at this ?{s}, we conclude that this measurement addresses the question about the presence of a hadronic spin flip due to the Pomeron exchange in polarized proton-proton elastic scattering.

Adamczyk, L.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alakhverdyants, A. V.; Alekseev, I.; Alford, J.; Anson, C. D.; Arkhipkin, D.; Aschenauer, E.; Averichev, G. S.; Balewski, J.; Banerjee, A.; Barnovska, Z.; Beavis, D. R.; Bellwied, R.; Betancourt, M. J.; Betts, R. R.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bruna, E.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Cai, X. Z.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chung, P.; Chwastowski, J.; Codrington, M. J. M.; Corliss, R.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derradi de Souza, R.; Dhamija, S.; Didenko, L.; Ding, F.; Dion, A.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Elnimr, M.; Engelage, J.; Eppley, G.; Eun, L.; Evdokimov, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Fersch, R. G.; Filip, P.; Finch, E.; Fisyak, Y.; Gagliardi, C. A.; Gangadharan, D. R.; Geurts, F.; Gibson, A.; Gliske, S.; Gorbunov, Y. N.; Grebenyuk, O. G.; Grosnick, D.; Gupta, S.; Guryn, W.; Haag, B.; Hajkova, O.; Hamed, A.; Han, L.-X.; Harris, J. W.; Hays-Wehle, J. P.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Huo, L.; Igo, G.; Jacobs, W. W.; Jena, C.; Judd, E. G.; Kabana, S.; Kang, K.; Kapitan, J.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Kikola, D. P.; Kiryluk, J.; Kisel, I.; Kisiel, A.; Kizka, V.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Koroleva, L.; Korsch, W.; Kotchenda, L.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; LaPointe, S.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Leight, W.; LeVine, M. J.; Li, C.; Li, L.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lima, L. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Lu, Y.; Luo, X.; Luszczak, A.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Mall, O. I.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Mioduszewski, S.; Mitrovski, M. K.; Mohammed, Y.; Mohanty, B.; Mondal, M. M.; Morozov, B.; Munhoz, M. G.; Mustafa, M. K.; Naglis, M.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nogach, L. V.; Novak, J.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Oliveira, R. A. N.; Olson, D.; Ostrowski, P.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Plyku, D.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Powell, C. B.; Pruneau, C.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Redwine, R.; Reed, R.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Ruan, L.; Rusnak, J.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, B.; Schmitz, N.; Schuster, T. R.; Seele, J.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shao, M.; Sharma, B.; Sharma, M.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; deSouza, U. G.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Steadman, S. G.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Sumbera, M.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szanto de Toledo, A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarini, L. H.; Tarnowsky, T.; Thein, D.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, Q.; Wang, X. L.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Whitten, C.; Wieman, H.; Wissink, S. W.; Witt, R.; Witzke, W.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, N.; Xu, Q. H.; Xu, W.; Xu, Y.; Xu, Z.; Xue, L.; Yang, Y.; Yang, Y.; Yepes, P.; Yi, Y.; Yip, K.; Yoo, I.-K.

2013-02-01

264

Single spin asymmetry AN in polarized proton-proton elastic scattering at s=200 GeV  

NASA Astrophysics Data System (ADS)

We report a high precision measurement of the transverse single spin asymmetry AN at the center of mass energy s=200 GeV in elastic proton-proton scattering by the STAR experiment at RHIC. The AN was measured in the four-momentum transfer squared t range 0.003?|t|?0.035 (, the region of a significant interference between the electromagnetic and hadronic scattering amplitudes. The measured values of AN and its t-dependence are consistent with a vanishing hadronic spin-flip amplitude, thus providing strong constraints on the ratio of the single spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated by the Pomeron amplitude at this s, we conclude that this measurement addresses the question about the presence of a hadronic spin flip due to the Pomeron exchange in polarized proton-proton elastic scattering.

STAR Collaboration; Adamczyk, L.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alakhverdyants, A. V.; Alekseev, I.; Alford, J.; Anson, C. D.; Arkhipkin, D.; Aschenauer, E.; Averichev, G. S.; Balewski, J.; Banerjee, A.; Barnovska, Z.; Beavis, D. R.; Bellwied, R.; Betancourt, M. J.; Betts, R. R.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bruna, E.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Cai, X. Z.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chung, P.; Chwastowski, J.; Codrington, M. J. M.; Corliss, R.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derradi de Souza, R.; Dhamija, S.; Didenko, L.; Ding, F.; Dion, A.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Elnimr, M.; Engelage, J.; Eppley, G.; Eun, L.; Evdokimov, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Fersch, R. G.; Filip, P.; Finch, E.; Fisyak, Y.; Gagliardi, C. A.; Gangadharan, D. R.; Geurts, F.; Gibson, A.; Gliske, S.; Gorbunov, Y. N.; Grebenyuk, O. G.; Grosnick, D.; Gupta, S.; Guryn, W.; Haag, B.; Hajkova, O.; Hamed, A.; Han, L.-X.; Harris, J. W.; Hays-Wehle, J. P.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Huo, L.; Igo, G.; Jacobs, W. W.; Jena, C.; Judd, E. G.; Kabana, S.; Kang, K.; Kapitan, J.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Kikola, D. P.; Kiryluk, J.; Kisel, I.; Kisiel, A.; Kizka, V.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Koroleva, L.; Korsch, W.; Kotchenda, L.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; LaPointe, S.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Leight, W.; LeVine, M. J.; Li, C.; Li, L.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lima, L. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Lu, Y.; Luo, X.; Luszczak, A.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Mall, O. I.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Mioduszewski, S.; Mitrovski, M. K.; Mohammed, Y.; Mohanty, B.; Mondal, M. M.; Morozov, B.; Munhoz, M. G.; Mustafa, M. K.; Naglis, M.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nogach, L. V.; Novak, J.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Oliveira, R. A. N.; Olson, D.; Ostrowski, P.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Plyku, D.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Powell, C. B.; Pruneau, C.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Redwine, R.; Reed, R.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Ruan, L.; Rusnak, J.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, B.; Schmitz, N.; Schuster, T. R.; Seele, J.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shao, M.; Sharma, B.; Sharma, M.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; deSouza, U. G.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Steadman, S. G.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Sumbera, M.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szanto de Toledo, A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarini, L. H.; Tarnowsky, T.; Thein, D.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, Q.; Wang, X. L.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Whitten, C.; Wieman, H.; Wissink, S. W.; Witt, R.; Witzke, W.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, N.; Xu, Q. H.; Xu, W.; Xu, Y.; Xu, Z.; Xue, L.; Yang, Y.; Yang, Y.; Yepes, P.; Yi, Y.

2013-02-01

265

The elastic behaviour of natural single crystals of the high-spin compound MnS2  

Microsoft Academic Search

The hydrostatic pressure and temperature dependences of velocities of ultrasonic modes propagated in natural single crystals of MnS2 have been measured. The elastic stiffness tensor components and the bulk modulus of this high-spin pyrite structure compound are much smaller than those of the low-spin isostructural crystal FeS2. This is consistent with MnS2 having substantially weaker attractive binding forces than those

G. A. Saunders; Wang Qingxian; E. F. Lambson; N. Lodge; D. Paine; W. Honle

1990-01-01

266

Selective coherent spin transportation in a spin-orbit-coupled bosonic junction  

NASA Astrophysics Data System (ADS)

We propose a theoretical scheme for realizing selective coherent spin transportation in a spin-orbit-coupled bosonic gas trapped in a symmetric double well by fast modulation of the energy-level unbalance between the two wells. The modulation can be tuned in such a way that an arbitrarily, a priori prescribed spin type (single spin or a spin pair with opposite spins) and the number of these spin bosons with or without spin flipping are allowed to tunnel. Furthermore, prescribed superexchange of spin bosons (where only pure spin exchange is allowed between the two wells and the atom number in each well is not changed) is also presented. The resonance conditions of realizing this selective coherent spin transportation are obtained analytically and confirmed numerically. This engineering provides a possible means for spin control and accurate counting or efficient filtering of the number of spins.

Yu, Zi-Fa; Xue, Ju-Kui

2014-09-01

267

Solution of a Sub-Riemannian Optimal Control Problem for a Quantum Spin System  

Microsoft Academic Search

Experiments in nuclear magnetic resonance (NMR) spectroscopy and NMR quantum computing require control of ensembles of quantum mechanical systems. The controlled transfer of coherence along a one-dimensional chain of spin systems plays a key role in NMR spectroscopy of proteins, and spin chains have also been proposed for NMR quantum information processing. The problem of time-optimal or energy-optimal control of

Amit K. Sanyal; Christopher Moseley; Anthony Bloch

268

Conditional Control of Donor Nuclear Spins in Silicon Using Stark Shifts  

NASA Astrophysics Data System (ADS)

Electric fields can be used to tune donor spins in silicon using the Stark shift, whereby the donor electron wave function is displaced by an electric field, modifying the hyperfine coupling between the electron spin and the donor nuclear spin. We present a technique based on dynamic decoupling of the electron spin to accurately determine the Stark shift, and illustrate this using antimony donors in isotopically purified silicon-28. We then demonstrate two different methods to use a dc electric field combined with an applied resonant radio-frequency (rf) field to conditionally control donor nuclear spins. The first method combines an electric-field induced conditional phase gate with standard rf pulses, and the second one simply detunes the spins off resonance. Finally, we consider different strategies to reduce the effect of electric field inhomogeneities and obtain above 90% process fidelities.

Wolfowicz, Gary; Urdampilleta, Matias; Thewalt, Mike L. W.; Riemann, Helge; Abrosimov, Nikolai V.; Becker, Peter; Pohl, Hans-Joachim; Morton, John J. L.

2014-10-01

269

Antiferromagnet-controlled spin current transport in SrMnO3/Pt hybrids  

NASA Astrophysics Data System (ADS)

We investigate the spin Hall magnetoresistance (SMR) in SrMn O3(SMO ) /Pt hybrids, where SMO is an antiferromagnetic (AFM) insulator. The AFM moments partially rotate with out-of-plane magnetic fields, producing room-temperature SMR. By manipulating the electron spins in Pt, we observe Larmor precession-induced oscillating SMR, reaffirming the spin current transport determined by the relative arrangement between the Pt electron spins and AFM moments. The use of the AFM with no net moments annihilates the magnetic proximity effect and thus confirms the SMR origination from AFM-controlled spin current transport, with significant spin mixing conductance of ˜1017m-2 . Our findings provide an interesting perspective to detecting AFM moments and represent a significant step towards AFM spintroincs.

Han, J. H.; Song, C.; Li, F.; Wang, Y. Y.; Wang, G. Y.; Yang, Q. H.; Pan, F.

2014-10-01

270

Controlling coherent and incoherent spin dynamics by steering the photoinduced energy flow  

NASA Astrophysics Data System (ADS)

We present a femtosecond spectroscopic magneto-optical investigation of the coherent and incoherent spin dynamics in the antiferromagnetic dielectric KNiF3. The pathways of the photoinduced energy flow to spins were controlled by tuning the pump photon energy. In particular, we demonstrate that laser pulses, with photon energy tuned to a nearly-zero-absorption region, excite the spin system without any signatures of heating of electrons or phonons. In this regime the ultrafast excitation of coherent spin waves is followed by a gradual increase of the spin temperature solely due to decoherence of the laser-generated magnons, as revealed by our simultaneous measurement of both the transversal and the longitudinal component of the spin dynamics.

Bossini, D.; Kalashnikova, A. M.; Pisarev, R. V.; Rasing, Th.; Kimel, A. V.

2014-02-01

271

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

NASA Astrophysics Data System (ADS)

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.

Hummel, Paul Jeremy

272

Effects of the covalent linker groups on the spin transport properties of single nickelocene molecules attached to single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The understanding of how the spin moment of a magnetic molecule transfers to a carbon nanotube, when the molecule is attached to it, is crucial for designing novel supramolecular spin devices. Here we explore such an issue by modeling the spin transport of a single-walled carbon nanotube grafted with one nickelocene molecule. In particular we investigate how the electron transport becomes spin-polarized depending on the specific linking group bonding nickelocene to the nanotube. We consider as linkers both aziridine and pyrrolidine rings and the amide group. Our calculations show that, at variance with aziridine, both pyrrolidine and amide, do alter the sp2 character of the binding site of the nanotube and thus affect the transmission around the Fermi level. However, only aziridine allows transferring the spin polarization of the nickelocene to the nanotube, whose conductance at the Fermi level becomes spin-polarized. This suggests the superiority of aziridine as a linker for grafting magnetic molecules onto carbon nanotubes with efficient spin filtering functionality.

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

2012-05-01

273

A scanning superconducting quantum interference device with single electron spin sensitivity.  

PubMed

Superconducting quantum interference devices (SQUIDs) can be used to detect weak magnetic fields and have traditionally been the most sensitive magnetometers available. However, because of their relatively large effective size (on the order of 1 µm), the devices have so far been unable to achieve the level of sensitivity required to detect the field generated by the spin magnetic moment (?B) of a single electron. Here we show that nanoscale SQUIDs with diameters as small as 46 nm can be fabricated on the apex of a sharp tip. The nano-SQUIDs have an extremely low flux noise of 50 n?0 Hz(-1/2) and a spin sensitivity of down to 0.38 ?B Hz(-1/2), which is almost two orders of magnitude better than previous devices. They can also operate over a wide range of magnetic fields, providing a sensitivity of 0.6 ?B Hz(-1/2) at 1 T. The unique geometry of our nano-SQUIDs makes them well suited to scanning probe microscopy, and we use the devices to image vortices in a type II superconductor, spaced 120 nm apart, and to record magnetic fields due to alternating currents down to 50 nT. PMID:23995454

Vasyukov, Denis; Anahory, Yonathan; Embon, Lior; Halbertal, Dorri; Cuppens, Jo; Neeman, Lior; Finkler, Amit; Segev, Yehonathan; Myasoedov, Yuri; Rappaport, Michael L; Huber, Martin E; Zeldov, Eli

2013-09-01

274

Single gimbal/strapdown inertial navigation system for use on spin stabilized flight test vehicles  

SciTech Connect

A hybrid strapdown inertial navigation system intended for use on spin stabilized flight test vehicles is described. The configuration of the navigator which is briefly described consists of three floated rate integrating gyros, one of which is used in conjunction with the gimbal with the remaining two operated in a rate gyro mode. Outputs from the two strapdown gyros and three accelerometers are digitized and processed by a high performance computer. The navigation algorithms utilize a direction cosine matrix formulation for the attitude computation implemented in the digital computer. The implementation of this algorithm for the single gimbal configuration is described. An accuracy model and results for a reentry vehicle flight test trajectory are presented. The flight test performance from launch to reentry is presented.

Watts, A.C.; Andreas, R.D.

1980-01-01

275

Single Spin Asymmetries in l p(transv. pol.) --> h X processes and TMD factorisation  

E-print Network

Some estimates for the transverse Single Spin Asymmetry, A_N, in the inclusive processes l p(transv. pol.) --> h X, 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 (l p(transv. pol.) --> l' h X). The factorisation in terms of Transverse Momentum Dependent distribution and fragmentation functions (TMD factorisation) -- i.e., the theoretical framework in which SIDIS azimuthal asymmetries are analysed -- is assumed to hold also for the inclusive process l p --> h X at large P_T. The values of A_N thus obtained agree in sign and shape with the data. Some predictions are given for future experiments.

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

2014-04-25

276

Processing, spinning, and fabrication of continuous fibers of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNTs) show great promise for use in a wide range of applications. One of the most promising avenues for attaining these applications is the dispersion of SWNTs at high concentrations in superacids and processing into macroscopic articles such as fibers or films. Fibers spun from SWNT/superacid dispersions indicate that the morphology of the starting SWNT material influences the final morphology of the as-spun fiber. Here, we describe a method (termed disentanglement) of dispersing SWNTs in superacids and treating them using a high-shear, rotor/stator homogenizer, followed by coagulation to recover the solid SWNT material for use in fiber spinning. Several lines of experimental evidence (rheology and optical microscopy of the SWNTs in solution, scanning electron microscopy (SEM) of the coagulated material, and SEM of fibers spun from the coagulated material) show that this disentanglement treatment radically improves the degree of alignment in the SWNTs' morphology, which in turn improves the dispersibility and processability. Raman microscopy and thermogravimetric analysis (TGA) before and after homogenization show that the treatment does not damage the SWNTs. Although this technique is particularly important as a pre-processing step for fiber spinning of neat SWNT fibers, it is also useful for neat SWNT films, SWNT/polymer composites, and surfactant- or polymer-stabilized SWNT dispersions. Macroscopic neat SWNT fibers were successfully produced and characterized. Studies on coagulated fiber morphology suggest that slow acid removal is crucial to minimizing voids. Better SWNT coalescence and alignment were obtained by using appropriate coagulant and dope concentration. SWNTs were disentangled and dissolved at high concentrations (8 - 10 wt%) in 102% sulfuric acid. Fibers were subsequently extruded by dry-jet wet spinning into ice water and polyvinyl alcohol (PVA) / ice water. Drawing the fiber continuously while spinning further aligned the SWNTs within the fiber. The use of PVA (< 1%) in the coagulant slowed acid removal allowing better SWNT coalescence without damaging the SWNT electrical properties. The resulting combination of pre-processing and fiber drawing shows a threefold improvement in fiber tensile strength.

Booker, Richard Delane

277

Single-shot quantum nondemolition measurement of a quantum-dot electron spin using cavity exciton-polaritons  

NASA Astrophysics Data System (ADS)

We propose a scheme to perform single-shot quantum nondemolition (QND) readout of the spin of an electron trapped in a semiconductor quantum dot (QD). Our proposal relies on the interaction of the QD electron spin with optically excited, quantum well (QW) microcavity exciton-polaritons. The spin-dependent Coulomb exchange interaction between the QD electron and cavity polaritons causes the phase and intensity response of left circularly polarized light to be different than that of right circularly polarized light, in such a way that the QD electron's spin can be inferred from the response to a linearly polarized probe reflected or transmitted from the cavity. We show that with careful device design it is possible to essentially eliminate spin-flip Raman transitions. Thus a QND measurement of the QD electron spin can be performed within a few tens of nanoseconds with fidelity ˜99.95%. This improves upon current optical QD spin readout techniques across multiple metrics, including speed and scalability.

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

2014-10-01

278

Spin mixing conductance at a well-controlled platinum/yttrium iron garnet interface  

NASA Astrophysics Data System (ADS)

A platinum (Pt)/yttrium iron garnet (YIG) bilayer system with a well-controlled interface has been developed; spin mixing conductance at the Pt/YIG interface has been studied. A clear interface with good crystal perfection is experimentally demonstrated to be one of the important factors for an ultimate spin mixing conductance. The spin mixing conductance is obtained to be 1.3 × 1018 m-2 at the well-controlled Pt/YIG interface, which is close to a theoretical prediction.

Qiu, Z.; Ando, K.; Uchida, K.; Kajiwara, Y.; Takahashi, R.; Nakayama, H.; An, T.; Fujikawa, Y.; Saitoh, E.

2013-08-01

279

ESR-STM of a single precessing spin: Detection of exchange-based spin noise A. V. Balatsky,1  

E-print Network

fluctuation is a relatively weak increaing function of the dc current and magnetic field. The linewidth case where the power spectrum of the spins of the tunneling electrons has a peak at zero frequency is the interference between two resonant tunneling components through the magnetic-field-split Zeeman levels.7 Both

Manassen, Yishay

280

On the design of single electron transistors for the measurement of spins in phosphorus doped silicon  

E-print Network

Phosphorus doped silicon is a prime candidate for spin based qubits. We plan to investigate a novel hybrid technique that combines the advantages of spin selective optical excitations with that of electrical readout ...

Randeria, Mallika

2012-01-01

281

Coherent spin control of a nanocavity-enhanced qubit in diamond  

E-print Network

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 (NV) 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 NV-memories, but scaling to larger networks requires more efficient spin-photon interfaces such as optical resonators. Here, we demonstrate such NV-nanocavity systems with optical quality factors approaching 10,000 and electron spin coherence times exceeding 200 $\\mu$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.

Luozhou Li; Tim Schröder; Edward H. Chen; Michael Walsh; Igal Bayn; Jordan Goldstein; Ophir Gaathon; Matthew E. Trusheim; Ming Lu; Jacob Mower; Mircea Cotlet; Matthew L. Markham; Daniel J. Twitchen; Dirk Englund

2014-09-04

282

Control Humidity With Single-Duct, Single-Zone, Constant Air Volume System  

E-print Network

), which turned this inefficient, humid lecture hall into a comfortable learning environment. This case study also explores other possibilities to solve the humidity control problem with single-duct, single-zone constant air volume systems....

Chen, H.; Deng, S.; Bruner, H. L.; Claridge, D. E.

2000-01-01

283

Evidence Of An Incommensurate Spin-Density Wave Instability In Single Crystal Bafe2as Detected By 75as NMR  

SciTech Connect

We report a {sup 75}As NMR study of BaFe{sub 2}As{sub 2} in both single crystal and polycrystal forms. The temperature dependence of the {sup 75}As NMR spectra shows magnetic broadening associated with a spin-density-wave instability at 85 K for the single crystal and at 138 K for the polycrystal material. The nuclear spin-lattice relaxation rate T{sub 1}{sup -1} exhibits a sharp maximum at the transition and is independent of field orientation in the single crystal. Our study suggests that there is no significant difference in the physics of single crystal and polycrystal BaFe{sub 2}As{sub 2} even though some properties differ qualitatively.

Baek, Seung H [Los Alamos National Laboratory; Klimczuk, Tomasz W [Los Alamos National Laboratory; Ronning, Filip [Los Alamos National Laboratory; Bauer, Eric D [Los Alamos National Laboratory; Thompson, Joe D [Los Alamos National Laboratory; Curro, Nicholas J [UC-DAVIS

2008-01-01

284

Control-system techniques for improved departure/spin resistance for fighter aircraft  

NASA Technical Reports Server (NTRS)

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.

Nguyen, L. T.; Gilbert, W. P.; Ogburn, M. E.

1980-01-01

285

Control system techniques for improved departure/spin resistance for fighter aircraft  

NASA Technical Reports Server (NTRS)

Some fundamental information on control system effects on controllability of highly-maneuverable aircraft at high angles of attack and techniques for enhancing fighter aircraft departure/spin resistance using control system design is summarized. The discussion includes: (a) a brief review of pertinent high angle-of-attack phenomena including aerodynamics, inertia coupling, and kinematic coupling; (b) effects of conventional stability augmentation systems at high-alpha; (c) high-alpha control system concepts designed to enhance departure/spin resistance; and (d) the outlook for applications of these concepts to future fighters, particularly those designs which incorporate relaxed static stability.

Nguyen, L. T.

1979-01-01

286

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

NASA Astrophysics Data System (ADS)

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.

Gingrich, Eric C.

287

Coherent control of the route of an ultrafast magnetic phase transition via low-amplitude spin precession.  

PubMed

Time-resolved magneto-optical imaging of laser-excited rare-earth orthoferrite (SmPr)FeO3 demonstrates that a single 60 fs circularly polarized laser pulse is capable of creating a magnetic domain on a picosecond time scale with a magnetization direction determined by the helicity of light. Depending on the light intensity and sample temperature, pulses of the same helicity can create domains with opposite magnetizations. We argue that this phenomenon relies on a twofold effect of light which (i) instantaneously excites coherent low-amplitude spin precession and (ii) triggers a spin reorientation phase transition. The former dynamically breaks the equivalence between two otherwise degenerate states with opposite magnetizations in the high-temperature phase and thus controls the route of the phase transition. PMID:22587282

de Jong, J A; Razdolski, I; Kalashnikova, A M; Pisarev, R V; Balbashov, A M; Kirilyuk, A; Rasing, Th; Kimel, A V

2012-04-13

288

Coherent Control of the Route of an Ultrafast Magnetic Phase Transition via Low-Amplitude Spin Precession  

NASA Astrophysics Data System (ADS)

Time-resolved magneto-optical imaging of laser-excited rare-earth orthoferrite (SmPr)FeO3 demonstrates that a single 60 fs circularly polarized laser pulse is capable of creating a magnetic domain on a picosecond time scale with a magnetization direction determined by the helicity of light. Depending on the light intensity and sample temperature, pulses of the same helicity can create domains with opposite magnetizations. We argue that this phenomenon relies on a twofold effect of light which (i) instantaneously excites coherent low-amplitude spin precession and (ii) triggers a spin reorientation phase transition. The former dynamically breaks the equivalence between two otherwise degenerate states with opposite magnetizations in the high-temperature phase and thus controls the route of the phase transition.

de Jong, J. A.; Razdolski, I.; Kalashnikova, A. M.; Pisarev, R. V.; Balbashov, A. M.; Kirilyuk, A.; Rasing, Th.; Kimel, A. V.

2012-04-01

289

Multiferroic M-type hexaferrites with a room-temperature conical state and magnetically controllable spin helicity.  

PubMed

Magnetic and magnetoelectric (ME) properties have been studied for single crystals of Sc-doped M-type barium hexaferrites. Magnetization (M) and neutron diffraction measurements revealed that by tuning Sc concentration a longitudinal conical state is stabilized up to above room temperatures. ME measurements have shown that a transverse magnetic field (H) can induce electric polarization (P) at lower temperatures and that the spin helicity is nonvolatile and endurable up to near the conical magnetic transition temperature. It was also revealed that the response (reversal or retention) of the P vector upon the reversal of M varies with temperature. In turn, this feature allows us to control the relation between the spin helicity and the M vectors with H and temperature. PMID:21231619

Tokunaga, Y; Kaneko, Y; Okuyama, D; Ishiwata, S; Arima, T; Wakimoto, S; Kakurai, K; Taguchi, Y; Tokura, Y

2010-12-17

290

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

SciTech Connect

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.

Frougier, J., E-mail: julien.frougier@thalesgroup.com; Jaffrès, H.; Deranlot, C.; George, J.-M. [Unité Mixte de Physique CNRS-Thales and Université Paris Sud 11, 1 av. Fresnel, 91767 Palaiseau (France)] [Unité Mixte de Physique CNRS-Thales and Université Paris Sud 11, 1 av. Fresnel, 91767 Palaiseau (France); Baili, G.; Dolfi, D. [Thales Research and Technology, 1 av. Fresnel, 91767 Palaiseau (France)] [Thales Research and Technology, 1 av. Fresnel, 91767 Palaiseau (France); Alouini, M. [Institut de Physique de Rennes, 263 Avenue Général Leclerc, 35042 Rennes (France)] [Institut de Physique de Rennes, 263 Avenue Général Leclerc, 35042 Rennes (France); Sagnes, I. [Laboratoire de Photonique et de Nanostructures, Route de Nozay, 91460 Marcoussis (France)] [Laboratoire de Photonique et de Nanostructures, Route de Nozay, 91460 Marcoussis (France); Garnache, A. [Institut d'électronique du Sud CNRS UMR5214, Université Montpellier 2 Place Eugene Bataillon, 34095 Montpellier (France)] [Institut d'électronique du Sud CNRS UMR5214, Université Montpellier 2 Place Eugene Bataillon, 34095 Montpellier (France)

2013-12-16

291

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

292

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

PubMed

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

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

293

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

NASA Astrophysics Data System (ADS)

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.

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

294

Spin Dynamics: A Paradigm for Time Optimal Control on Compact Lie Groups  

Microsoft Academic Search

The development of efficient time optimal control strategies for coupled spin systems plays a fundamental role in nuclear\\u000a magnetic resonance (NMR) spectroscopy. In particular, one of the major challenges lies in steering a given spin system to\\u000a a maximum of its so-called transfer function. In this paper we study in detail these questions for a system of two weakly\\u000a coupled

G. Dirr; U. helmke; K. Hüper; M. Kleinsteuber; Y. Liu

2006-01-01

295

Most spin-1/2 transition-metal ions do have single ion anisotropy  

NASA Astrophysics Data System (ADS)

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 Cu2+ ions in CuCl2.2H2O, LiCuVO4, CuCl2, and CuBr2 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 Cu2+ ions of Bi2CuO4 and Li2CuO2. 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.

Liu, Jia; Koo, Hyun-Joo; Xiang, Hongjun; Kremer, Reinhard K.; Whangbo, Myung-Hwan

2014-09-01

296

Optically induced nuclear spin polarization in a single GaAs/AlGaAs quantum well probed by a resistance detection method in the fractional quantum Hall regime  

E-print Network

We study the optically pumped nuclear spin polarization in a single GaAs/AlGaAs quantum well in the quantum Hall system. We apply resistive detection via the contact hyperfine interaction, which provides high sensitivity and selectivity, to probe a small amount of polarized nuclear spins in a single well. The properties of the optical nuclear spin polarization are clearly observed. We theoretically discuss the nuclear spin dynamics accompanied with doped electrons to analyze the experimental data. The optical nuclear polarization spectra exhibit electron-spin-resolved lowest Landau level interband transitions. We find that the phonon emission process, which normally assists the optical pumping process, influences the optical nuclear spin polarization. We also discuss that the electron-electron interaction can play an important role in the optical nuclear spin polarization.

K. Akiba; T. Yuge; S. Kanasugi; K. Nagase; Y. Hirayama

2012-06-22

297

Forward Neutral Pion Transverse Single Spin Asymmetries in p+p Collisions at \\sqrt{s}=200 GeV  

E-print Network

We report precision measurements of the Feynman-x dependence, and first measurements of the transverse momentum dependence, of transverse single spin asymmetries for the production of \\pi^0 mesons from polarized proton collisions at \\sqrt{s}=200 GeV. The x_F dependence of the results are in fair agreement with perturbative QCD model calculations that identify orbital motion of quarks and gluons within the proton as the origin of the spin effects. Results for the p_T dependence at fixed x_F are not consistent with pQCD-based calculations.

Abelev, B I; Ahammed, Z; Anderson, B D; Arkhipkin, D; Averichev, G S; Bai, Y; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Baumgart, S; Beavis, D R; Bellwied, R; Benedosso, F; Betts, R R; Bhardwaj, S; Bhasin, A; Bhati, A K; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Blyth, S-L; Bombara, M; Bonner, B E; Botje, M; Bouchet, J; Braidot, E; Brandin, A V; Bültmann, S; Burton, T P; Bystersky, M; Cai, X Z; Caines, H; Calderón de la Barca-Sanchez, M; Callner, J; Catu, O; Cebra, D; Cervantes, M C; Chajecki, Z; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, J Y; Cheng, J; Cherney, M; Chikanian, A; Choi, K E; Christie, W; Chung, S U; Clarke, R F; Codrington, M J M; Coffin, J P; Cormier, T M; Cosentino, M R; Cramer, J G; Crawford, H J; Das, D; Dash, S; Daugherity, M; De Moura, M M; Dedovich, T G; De Phillips, M; Derevshchikov, A A; Derradide Souza, R; Didenko, L; Dietel, T; Djawotho, P; Dogra, S M; Dong, X; Drachenberg, J L; Draper, J E; Du, F; Dunlop, J C; Dutta-Majumdar, M R; Edwards, W R; Efimov, L G; Elhalhuli, E; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Estienne, M; Eun, L; Fachini, P; Fatemi, R; Fedorisin, J; Feng, A; Filip, P; Finch, E; Fine, V; Fisyak, Yu; Fu, J; Gagliardi, C A; Gaillard, L; Ganti, M S; García-Solis, E; Ghazikhanian, V; Ghosh, P; Gorbunov, Y N; Gordon, A; Gos, H; Grebenyuk, O; Grosnick, D; Grube, B; Guertin, S M; Guimaraes, K S F F; Sen-Gupta, A; Gupta, N; Guryn, W; Haag, B; Hallman, T J; Hamed, A; Harris, J W; He, W; Heinz, M; Henry, T W; Heppelmann, S; Hippolyte, B; Hirsch, A; Hjort, E; Hoffman, A M; Hoffmann, G W; Hofman, D J; Hollis, R S; Horner, M J; Huang, H Z; Hughes, E W; Humanic, T J; Igo, G; Iordanova, A; Jacobs, P; Jacobs, W W; Jakl, P; Jin, F; Jones, P G; Judd, E G; Kabana, S; Kajimoto, K; Kang, K; Kapitan, J; Kaplan, M; Keane, D; Kechechyan, A; Kettler, D; Khodyrev, V Yu; Kiryluk, J; Kisiel, A; Klein, S R; Knospe, A G; Kocoloski, A; Koetke, D D; Kollegger, T; Kopytine, M; Kotchenda, L; Kouchpil, V; Kowalik, K L; Kravtsov, P; Kravtsov, V I; Krüger, K; Kuhn, C; Kumar, A; Kurnadi, P; Lamont, M A C; Landgraf, J M; Langdon, J; Lange, S; La Pointe, S; Laue, F; Lauret, J; Lebedev, A; Lednicky, R; Lee, C-H; Le Vine, M J; Li, C; Li, Q; Li, Y; Lin, G; Lin, X; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, H; Liu, J; Liu, L; Ljubicic, T; Llope, W J; Longacre, R S; Love, W A; Lu, Y; Ludlam, T; Lynn, D; Ma, G L; Ma, J G; Ma, Y G; Mahapatra, D P; Majka, R; Mangotra, L K; Manweiler, R; Margetis, S; Markert, C; Matis, H S; Matulenko, Yu A; McShane, T S; Meschanin, A; Millane, J; Miller, C; Miller, M L; Minaev, N G; Mioduszewski, S; Mischke, A; Mitchell, J; Mohanty, B; Morozov, D A; Munhoz, M G; Nandi, B K; Nattrass, C; Nayak, T K; Nelson, J M; Nepali, C; Netrakanti, P K; Ng, M J; Nogach, L V; Nurushev, S B; Odyniec, Grazyna Janina; Ogawa, A; Okada, H; Okorokov, V; Olson, D; Pachr, M; Pal, S K; Panebratsev, Yu A; Pavlinov, A I; Pawlak, T; Peitzmann, T; Perevozchikov, V; Perkins, C; Peryt, W; Phatak, S C; Planinic, M; Pluta, J; Poljak, N; Porile, N; Poskanzer, A M; Potekhin, M; Potukuchi, B V K S; Prindle, D; Pruneau, C; Pruthi, N K; Putschke, J; Qattan, I A; Rakness, G; Raniwala, R; Raniwala, S; Ray, R L; Relyea, D; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Ruan, L; Russcher, M J; Rykov, V; Sahoo, R; Sakrejda, I; Sakuma, T; Salur, S; Sandweiss, J; Sarsour, M; Schambach, J; Scharenberg, R P; Schmitz, N; Seger, J; Selyuzhenkov, I; Seyboth, P; Shabetai, A; Shahaliev, E; Shao, M; Sharma, M; Shi, X-H; Sichtermann, E P; Simon, F; Singaraju, R N; Skoby, M J; Smirnov, N; Snellings, R; Sørensen, P; Sowinski, J; Speltz, J; Spinka, H M; Srivastava, B; Stadnik, A; Stanislaus, T D S; Staszak, D; Stock, R; Strikhanov, M; Stringfellow, B; Suaide, A A P; Suarez, M C; Subba, N L; Sumbera, M; Sun, X M; Sun, Z; Surrow, B; Symons, T J M; Szanto de Toledo, A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Tatarowicz, J; Thein, D; Thomas, J H; Tian, J; Timmins, A R; Timoshenko, S; Tokarev, M; Trainor, T A; Tram, V N; Trattner, A L; Trentalange, S; Tribble, R E; Tsai, O D; Ulery, J; Ullrich, T; Underwood, D G; Van Buren, G; Van der Kolk, N; Van Leeuwen, M; Van der Molen, A M; Varma, R; Vasconcelos, G M S; Vasilevski, I M; Vasilev, A N; Vernet, R; Videbaek, F; Vigdor, S E; Viyogi, Y P; Vokal, S; Voloshin, S A; Wada, M; Waggoner, W T; Wang, F; Wang, G; Wang, J S; Wang, Q; Wang, X; Wang, X L; Wang, Y; Webb, J C; Westfall, G D; Whitten, C; Wieman, H; Wissink, S W; Witt, R; Wu, J; Wu, Y; Xu, N; Xu, Q H; Xu, Z; Yepes, P; Yoo, I-K; Yue, Q; Zachariou, N; Zawisza, M; Zhan, W; Zhang, H; Zhang, S; Zhang, W M; Zhang, Y; Zhang, Z P; Zhao, Y; Zhong, C; Zhou, J; Zoulkarneev, R; Zoulkarneeva, Y; Zuo, J X

2008-01-01

298

Helicity asymmetry E measurement for single pi^0 photoproduction with a frozen spin target  

SciTech Connect

The helicity asymmetry for single neutral pion photoproduction was measured using the CLAS detector in Hall B at the Thomas Jefferson National Accelerator Facility. This measurement used longitudinally polarized protons and circularly polarized photons with photon energies between 0.35 GeV to 2.4 GeV. The target was a frozen-spin butanol (C{sub 4}H{sub 9}OH) target, polarized at about 85%. The helicity asymmetry E for the {gamma}p {yields} p{pi}{sup 0} was measured with missing-mass technique at the high statistics of about 12 x 10{sup 6} events. The experimental results are compared to three available theoretical predictions, SAID, MAID, and EBAC. The preliminary results are in good agreement with the model calculations at low E{sub {gamma}} energy bins. However, a significant deviation is observed at high energy bins. Therefore, the new data will help to constrain the parameters of the theoretical models.

Hideko Iwamoto

2012-04-01

299

Multi-Sensor Single-Actuator Control of HVAC Systems  

E-print Network

It is common to control several rooms in a building with a single sensor in one of the rooms and a single actuator driving just one control element such as an air damper. New, low-cost, wireless sensor technology now offers the opportunity...

Lin, C.; Auslander, D.; Federspiel, C.

2002-01-01

300

Single-Chip Microcomputer Control Of The PWM Inverter  

NASA Astrophysics Data System (ADS)

A single-chip microcomputer-based con-troller for a pulsewidth modulated 1.7 KVA inverter of an airconditioner is presented. The PWM pattern generation and the system control of the airconditioner are achieved by software of the 8-bit single-chip micro-computer. The single-chip microcomputer has the disadvantages of low processing speed and small memory capacity which can be overcome by the magnetic flux control method. The PWM pattern is generated every 90 psec. The memory capacity of the PWM look-up table is less than 2 kbytes. The simple and reliable control is realized by the software-based implementation.

Morimoto, Masayuki; Sato, Shinji; Sumito, Kiyotaka; Oshitani, Katsumi

1987-10-01

301

Electrostatic spin control in InAs/InP nanowire quantum dots.  

PubMed

Very robust voltage-controlled spin transitions in few-electron quantum dots are demonstrated. Two lateral-gate electrodes patterned on opposite sides of an InAs/InP nanowire are used to apply a transverse electric field and tune orbital energy separation down to level-pair degeneracy. Transport measurements in this regime allow us to demonstrate the breakdown of the standard alternate up/down spin filling scheme and unambiguously show singlet-triplet spin transitions. The strong confinement of the present devices leads to a large energy gain for the observed anomalous spin configurations that exceeds 4 meV. As a consequence, this behavior is well visible even at temperatures exceeding T = 20 K. PMID:22849393

Romeo, Lorenzo; Roddaro, Stefano; Pitanti, Alessandro; Ercolani, Daniele; Sorba, Lucia; Beltram, Fabio

2012-09-12

302

Experimental Realization of a Quantum Integer-Spin Chain with Controllable Interactions  

E-print Network

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 forces on trapped 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. We observe the time evolution of the system and verify its coherence by entangling a pair of effective three-level particles (`qutrits') with 86% fidelity. By adiabatically ramping a global field, we produce ground states of the XY model, and we demonstrate an instance where the ground state cannot be created without breaking the same symmetries that protect the topological Haldane phase. This experimental platform enables future studies of symmetry...

Senko, C; Smith, J; Lee, A; Cohen, I; Retzker, A; Monroe, C

2014-01-01

303

Opposing spin-canting mechanism in single-crystal LuV O3 and YV O3  

NASA Astrophysics Data System (ADS)

A canted-spin ferromagnetic moment M parallel to the orthorhombic ( Pbnm ) a axis of a YV O3 single crystal changes sign from the direction of a measuring field H?1 kOe on warming from 5 K across a first-order orbital-spin reordering temperature TCG ; the magnetization changes sign again on warming across T* in the interval TCG < T* < TN , where TN is the antiferromagnetic Néel temperature. Although the magnitude of M and its sign changes are the same for a sample cooled in a measuring field (FC) and zero-applied field (ZFC) to 5 K , the M (T) curves differ for warming after FC and ZFC to just above TCG ; but the sign reversal of M occurs at the same T* with the same measuring field H . These unusual features are argued to be the result of two coupled spin-canting mechanisms that oppose one another, an antisymmetric exchange operating on a c -axis spin component, and a 90° site anisotropy in the a-b plane operating on a b -axis component of the spin. The relative strength of the antisymmetric exchange increases with decreasing V-O-V bond angle to give a T* close to a TOO ? TN in LaV O3 and no T* above TCG in LuV O3 .

Yan, J.-Q.; Zhou, J.-S.; Goodenough, J. B.

2005-09-01

304

Modeling the Spin Motor Current of the International Space Station's Control Moment Gyroscopes  

NASA Technical Reports Server (NTRS)

The International Space Station (ISS) attitude control is provided by two means: The Russian Segment uses thrusters and the U.S. Segment uses double-gimbaled control moment gyroscopes (CMG). CMGs are used as momentum exchange devices, providing non propulsive attitude control for the vehicle. The CMGs are very important for the ISS program because, first, they save propellant - which needs to be transferred to the Station in special cargo vehicles - and, second, they provide the microgravity environment on the Station - which is necessary for scientific experiments planned for the ISS mission. Since 2002, when one of the CMG on the ISS failed, all CMGs are closely monitored. High gimbal rates, vibration spikes, unusual variations of spin motor current and bearing temperatures are of great concern, since these parameters are the CMG health indicators. The telemetry analysis of these and some other CMG parameters is used to determine constrains and make changes to the CMGs operation on board. These CMG limitations, in turn, may limit the ISS attitude control capabilities and may be critical to ISS operation. Therefore, it is important to know whether the CMG parameter is nominal or out of family, and why. The goal of this project is to analyze an important CMG parameter - spin motor current. Some operational decisions are made now based on the spin motor current signatures. The spin motor current depends on gimbal rates, ISS rates, and spin bearing friction. The spin bearing friction in turn depends on the bearing temperatures, wheel rates, normal load - which is a function of gimbal and wheel rates - lubrication, etc. The first task of this project is to create a spin motor current mathematical model based on CMG dynamics model and the current knowledge on bearing friction in microgravity.

Pereira, Miguel A.

2008-01-01

305

Coherence rephasing combined with spin-wave storage using chirped control pulses  

NASA Astrophysics Data System (ADS)

Photon-echo based optical quantum memory schemes often employ intermediate steps to transform optical coherences to spin coherences for longer storage times. We analyze a scheme that uses three identical chirped control pulses for coherence rephasing in an inhomogeneously broadened ensemble of three-level ? systems. The pulses induce a cyclic permutation of the atomic populations in the adiabatic regime. Optical coherences created by a signal pulse are stored as spin coherences at an intermediate time interval, and are rephased for echo emission when the ensemble is returned to the initial state. Echo emission during a possible partial rephasing when the medium is inverted can be suppressed with an appropriate choice of control pulse wave vectors. We demonstrate that the scheme works in an optically dense ensemble, despite control pulse distortions during propagation. It integrates conveniently the spin-wave storage step into memory schemes based on a second rephasing of the atomic coherences.

Demeter, Gabor

2014-06-01

306

Reversible control of spin-polarized supercurrents in ferromagnetic Josephson junctions  

NASA Astrophysics Data System (ADS)

Magnetic inhomogeneity at a superconductor (S)–ferromagnet (F) interface converts spin-singlet Cooper pairs into spin-one triplet pairs. These pairs are immune to the pair-breaking exchange field in F and support a long-range proximity effect. Although recent experiments have confirmed the existence of spin-polarized triplet supercurrents in S–F–S Josephson junctions, reversible control of the supercurrent has been impossible because of the robust preconfigured nature of the inhomogeneity. Here, we use a barrier comprising three F layers whose relative magnetic orientation, and hence the interfacial inhomogeneity, can be controlled by small magnetic fields; we show that this enables full control of the triplet supercurrent and, by using finite element micromagnetic simulations, we can directly relate the experimental data to the theoretical models which provide a general framework to understand the role played by magnetic states in long-range supercurrent modulation.

Banerjee, N.; Robinson, J. W. A.; Blamire, M. G.

2014-08-01

307

Coherence rephasing combined with spin-wave storage using chirped control pulses  

E-print Network

Photon-echo based optical quantum memory schemes often employ intermediate steps to transform optical coherences to spin coherences for longer storage times. We analyze a scheme that uses three identical chirped control pulses for coherence rephasing in an inhomogeneously broadened ensemble of three-level $\\Lambda$-systems. The pulses induce a cyclic permutation of the atomic populations in the adiabatic regime. Optical coherences created by a signal pulse are stored as spin coherences at an intermediate time interval, and are rephased for echo emission when the ensemble is returned to the initial state. Echo emission during a possible partial rephasing when the medium is inverted can be suppressed with an appropriate choice of control pulse wavevectors. We demonstrate that the scheme works in an optically dense ensemble, despite control pulse distortions during propagation. It integrates conveniently the spin-wave storage step into memory schemes based on a second rephasing of the atomic coherences.

Gabor Demeter

2014-03-19

308

Spin and Orbital Effects of Cooper Pairs Coupled to a Single Magnetic Impurity  

NASA Astrophysics Data System (ADS)

The Kondo effect strongly depends on spin and orbital degrees of freedom of unconventional superconductivity. We focus on the Kondo effect in uniformly gapped superconducting systems (the two-dimensional px + i p_y-wave and d_x^2 - y^2 + i d_xy-wave superconductors here) to compare the magnetic properties of the spin-triplet and spin-singlet Cooper pairs[1]. The difference appears when both of the paired electrons couple to a local spin directly. For the px + i p_y-wave, the ground state is always a spin doublet for a S_imp = 1/2 local spin, and it is always a spin singlet for S_ imp = 1. The latter is due to uniaxial spin anisotropy of the triplet Cooper pair. For the d_x^2 - y^2 + i d_xy-wave, the interchange of ground states occurs, which resembles a competition between the Kondo effect and the superconducting energy gap in s-wave superconductors. Thus the internal degrees of freedom of Cooper pairs give a variety to the Kondo effect. [1] M. Koga and M. Matsumoto, cond-mat/0109513.

Koga, Mikito; Matsumoto, Masashige

2002-03-01

309

Room-temperature spin-polarized organic light-emitting diodes with a single ferromagnetic electrode  

NASA Astrophysics Data System (ADS)

In this paper, we demonstrate the concept of a room-temperature spin-polarized organic light-emitting diode (Spin-OLED) structure based on (i) the deposition of an ultra-thin p-type organic buffer layer on the surface of the ferromagnetic electrode of the Spin-OLED and (ii) the use of oxygen plasma treatment to modify the surface of that electrode. Experimental results demonstrate that the brightness of the developed Spin-OLED can be increased by 110% and that a magneto-electroluminescence of 12% can be attained for a 150 mT in-plane magnetic field, at room temperature. This is attributed to enhanced hole and room-temperature spin-polarized injection from the ferromagnetic electrode, respectively.

Ding, Baofu; Song, Qunliang; Alameh, Kamal

2014-05-01

310

Forward Neutral-Pion Transverse Single-Spin Asymmetries in p plus p Collisions at s=200 GeV  

Microsoft Academic Search

We report precision measurements of the Feynman x (x{sub F}) dependence, and first measurements of the transverse momentum (p{sub T}) dependence, of transverse single-spin asymmetries for the production of ° mesons from polarized proton collisions at (s)=200 GeV. The x{sub F} dependence of the results is in fair agreement with perturbative QCD model calculations that identify orbital motion of quarks

B. I. Abelev; M. M. Aggarwal; Z. Ahammed; B. D. Anderson; D. Arkhipkin; G. S. Averichev; Y. Bai; J. Balewski; O. Barannikova; L. S. Barnby; J. Baudot; S. Baumgart; D. R. Beavis; R. Bellwied; F. Benedosso; R. R. Betts; S. Bhardwaj; A. Bhasin; A. K. Bhati; H. Bichsel; J. Bielcik; J. Bielcikova; L. C. Bland; S. L. Blyth; M. Bombara; B. E. Bonner; M. Botje; J. Bouchet; E. Braidot; A. V. Brandin; S. Bueltmann; T. P. Burton; M. Bystersky; X. Z. Cai; H. Caines; M. C. D. Sanchez; J. Callner; O. Catu; D. Cebra; M. C. Cervantes; Z. Chajecki; P. Chaloupka; S. Chattopadhyay; H. F. Chen; J. H. Chen; J. Cheng; M. Cherney; A. Chikanian; K. E. Choi; W. Christie; S. U. Chung; R. F. Clarke; M. J. M. Codrington; J. P. Coffin; T. M. Cormier; M. R. Cosentino; J. G. Cramer; H. J. Crawford; D. Das; S. Dash; M. Daugherity; M. M. de Moura; T. G. Dedovich; M. DePhillips; A. A. Derevschikov; R. D. de Souza; L. Didenko; T. Dietel; P. Djawotho; S. M. Dogra; X. Dong; J. L. Drachenberg; J. E. Draper; F. Du; J. C. Dunlop; M. R. D. Mazumdar; W. R. Edwards; L. G. Efimov; E. Elhalhuli; V. Emelianov; J. Engelage; G. Eppley; B. Erazmus; M. Estienne; L. Eun; P. Fachini; R. Fatemi; J. Fedorisin; A. Feng; P. Filip; E. Finch; V. Fine; Y. Fisyak; J. Fu; C. A. Gagliardi; L. Gaillard; M. S. Ganti; E. Garcia-Solis; V. Ghazikhanian; P. Ghosh; Y. N. Gorbunov; A. Gordon; H. Gos; O. Grebenyuk; D. Grosnick; B. Grube; S. M. Guertin; Ksff Guimaraes; A. Gupta; N. Gupta; W. Guryn; B. Haag; T. J. Hallman; A. Hamed; J. W. Harris; W. He; M. Heinz; T. W. Henry; S. Heppelmann; B. Hippolyte; A. Hirsch; E. Hjort; A. M. Hoffman; G. W. Hoffmann; D. J. Hofman; R. S. Hollis; M. J. Horner; H. Z. Huang; E. W. Hughes; T. J. Humanic; G. Igo; A. Iordanova; P. Jacobs; W. W. Jacobs; P. Jakl; F. Jin; P. G. Jones; E. G. Judd; S. Kabana; K. Kajimoto; K. Kang; J. Kapitan; M. Kaplan; D. Keane; A. Kechechyan; D. Kettler; V. Y. Khodyrev; J. Kiryluk; A. Kisiel; S. R. Klein; A. G. Knospe; A. Kocoloski; D. D. Koetke; T. Kollegger; M. Kopytine; L. Kotchenda; V. Kouchpil; K. L. Kowalik; P. Kravtsov; V. I. Kravtsov; K. Krueger; C. Kuhn; A. Kumar; P. Kurnadi; M. A. C. Lamont; J. M. Landgraf; J. Langdon; S. Lange; S. LaPointe; F. Laue; J. Lauret; A. Lebedev; R. Lednicky; C. H. Lee; M. J. LeVine; C. Li; Q. Li; Y. Li; G. Lin; X. Lin; S. J. Lindenbaum; M. A. Lisa; F. Liu; H. Liu; J. Liu; L. Liu; T. Ljubicic; W. J. Llope; R. S. Longacre; W. A. Love; Y. Lu; T. Ludlam; D. Lynn; G. L. Ma; J. G. Ma; Y. G. Ma; D. P. Mahapatra; R. Majka; L. K. Mangotra; R. Manweiler; S. Margetis; C. Markert; H. S. Matis; Y. A. Matulenko; T. S. McShane; A. Meschanin; J. Millane; C. Miller; M. L. Miller; N. G. Minaev; S. Mioduszewski; A. Mischke; J. Mitchell; B. Mohanty; D. A. Morozov; M. G. Munhoz; B. K. Nandi; C. Nattrass; T. K. Nayak; J. M. Nelson; C. Nepali; P. K. Netrakanti; M. J. Ng; L. V. Nogach; S. B. Nurushev; G. Odyniec; A. Ogawa; H. Okada; V. Okorokov; D. Olson; M. Pachr; S. K. Pal; Y. Panebratsev; A. I. Pavlinov; T. Pawlak; T. Peitzmann; V. Perevoztchikov; C. Perkins; W. Peryt; S. C. Phatak; M. Planinic; J. Pluta; N. Poljak; N. Porile; A. M. Poskanzer; M. Potekhin; Bvks Potukuchi; D. Prindle; C. Pruneau; N. K. Pruthi; J. Putschke; I. A. Qattan; G. Rakness; R. Raniwala; S. Raniwala; R. L. Ray; D. Relyea; A. Ridiger; H. G. Ritter; J. B. Roberts; O. V. Rogachevskiy; J. L. Romero; A. Rose; C. Roy; L. Ruan; M. J. Russcher; V. Rykov; R. Sahoo; I. Sakrejda; T. Sakuma; S. Salur; J. Sandweiss; M. Sarsour; J. Schambach; R. P. Scharenberg; N. Schmitz; J. Seger; I. Selyuzhenkov; P. Seyboth; A. Shabetai; E. Shahaliev; M. Shao; M. Sharma; X. H. Shi; E. P. Sichtermann; F. Simon; R. N. Singaraju; M. J. Skoby; N. Smirnov; R. Snellings; P. Sorensen; J. Sowinski; J. Speltz; H. M. Spinka; B. Srivastava; A. Stadnik; T. D. S. Stanislaus; D. Staszak; R. Stock; M. Strikhanov; B. Stringfellow; A. A. P. Suaide; M. C. Suarez; N. L. Subba; M. Sumbera; X. M. Sun; Z. Sun; B. Surrow; T. J. M. Symons; A. S. de Toledo; J. Takahashi; A. H. Tang; Z. Tang; T. Tarnowsky; J. Tatarowicz; D. Thein; J. H. Thomas; J. Tian; A. R. Timmins; S. Timoshenko; M. Tokarev; T. A. Trainor; V. N. Tram; A. L. Trattner; S. Trentalange; R. E. Tribble; O. D. Tsai; J. Ulery; T. Ullrich; D. G. Underwood; G. Van Buren; N. van der Kolk; M. van Leeuwen; A. M. Vander Molen; R. Varma; G. M. S. Vasconcelos; I. M. Vasilevski; A. N. Vasiliev; R. Vernet; F. Videbaek; S. E. Vigdor; Y. P. Viyogi; S. Vokal; S. A. Voloshin; M. Wada; W. T. Waggoner; F. Wang; G. Wang; J. S. Wang; Q. Wang; X. Wang; Y. Wang; J. C. Webb; G. D. Westfall; C. J. Whitten; H. Wieman; S. W. Wissink; R. Witt; J. Wu; Y. Wu; N. Xu; Q. H. Xu; Z. Xu; P. Yepes; I. K. Yoo; Q. Yue; N. Zachariou; M. Zawisza; W. Zhan; H. Zhang; S. Zhang; W. M. Zhang; Y. Zhang; Z. P. Zhang; Y. Zhao; C. Zhong; J. Zhou; R. Zoulkarneev; Y. Zoulkarneeva; J. X. Zuo

2008-01-01

311

Single-Shot Time Domain Studies of Spin-Torque-Driven Switching and Precession in Magnetic Tunnel Junctions  

Microsoft Academic Search

We present single-shot time domain resistance measurements of spin-transfer-driven dynamics in CoFeB\\/MgO\\/CoFeB tunnel junctions. In the regime of thermally-activated current-driven switching, we have sufficient sensitivity to resolve the pattern of resistance oscillations caused by the magnetic dynamics leading up to switching. When an in-plane hard-axis magnetic field is applied, within a short interval before the switching instant the resistance oscillations

Yong-Tao Cui; Robert A. Buhrman; Daniel C. Ralph; Daniele Mauri; Jordan A. Katine

2009-01-01

312

Spin-reorientation and anisotropy of the magnetization in single crystalline Ho 2Co 15Si 2  

Microsoft Academic Search

We have studied the magnetic properties of a Ho2Co15Si2 single crystal. The easy magnetization direction is parallel to the c-axis in an extended temperature region below the Curie temperature. A spin-reorientation transition takes place at 323 K, leading to an easy magnetization direction perpendicular to the c-axis below this temperature. We have compared the present results with those obtained previously

O Tegus; E. H. Bruck; A. A. Menovsky; F. R de Boer; K. H. J. Buschow

2000-01-01

313

Graphene Enabled Low-Control Quantum Gates between Static and Mobile Spins  

E-print Network

We show that the feature of Klein tunneling makes graphene a unique interface for implementing low control quantum gates between static and mobile qubits. A ballistic electron spin is considered as the mobile qubit, while the static qubit is the electronic spin of a quantum dot fixed in a graphene nanoribbon. Scattering is the low control mechanism of the gate, which, in other systems, is really difficult to exploit because of both back-scattering and the momentum dependence of scattering. We find that Klein tunneling enables the implementation of quasi-deterministic quantum gates regardless of the momenta or the shape of the wave function of the incident electron. The Dirac equation is used to describe the system in the one particle approximation with the interaction between the static and the mobile spins modelled by a Heisenberg Hamiltonian. Furthermore, we discuss an application of this model to generate entanglement between two well separated static qubits.

G. Cordourier-Maruri; Y. Omar; R. de Coss; S. Bose

2013-06-30

314

Single-Chain Magnetic Behavior in a Hetero-Tri-Spin Complex Mediated by Supramolecular Interactions with TCNQF(.-) Radicals.  

PubMed

The self-assembly of organic TCNQF(.-) radicals (2-fluoro-7,7,8,8-tetracyano-p-quinodimethane) and the anisotropic [Tb(valpn)Cu](3+) dinuclear cations produced a single-chain magnet (SCM) involving stacking interactions of TCNQF(.-) radicals (H2 valpn is the Schiff base from the condensation of o-vanillin with 1,3-diaminopropane). Static and dynamic magnetic characterizations reveal that the effective energy barrier for the reversal of the magnetization in this hetero-tri-spin SCM is significantly larger than the barrier of the isolated single-molecule magnet based on the {TbCu} dinuclear core. PMID:25213266

Wang, Zhao-Xi; Zhang, Xuan; Zhang, Yuan-Zhu; Li, Ming-Xing; Zhao, Hanhua; Andruh, Marius; Dunbar, Kim R

2014-10-20

315

Cavity-stimulated Raman emission from a single quantum dot spin  

NASA Astrophysics Data System (ADS)

Solid-state quantum emitters have shown strong potential for applications in quantum information, but the spectral inhomogeneity of these emitters poses a significant challenge. We address this issue in a cavity-quantum dot system by demonstrating cavity-stimulated Raman spin flip emission. This process avoids populating the excited state of the emitter and generates a photon that is Raman shifted from the laser and enhanced by the cavity. The emission is spectrally narrow and tunable over a range of at least 125 GHz, which is two orders of magnitude greater than the natural linewidth. We obtain the regime in which the Raman emission is spin dependent, which couples the photon to a long-lived electron spin qubit. This process can enable an efficient, tunable source of indistinguishable photons and deterministic entanglement of distant spin qubits in a photonic-crystal quantum network.

Sweeney, Timothy M.; Carter, Samuel G.; Bracker, Allan S.; Kim, Mijin; Kim, Chul Soo; Yang, Lily; Vora, Patrick M.; Brereton, Peter G.; Cleveland, Erin R.; Gammon, Daniel

2014-06-01

316

Control of single-photon transport in a one-dimensional waveguide by a single photon  

NASA Astrophysics Data System (ADS)

We study controllable single-photon transport in a one-dimensional waveguide with a nonlinear dispersion relation coupled to a three-level emitter in a cascade configuration. An extra cavity field is introduced to drive one of the level transitions of the emitter. In the resonance case, when the extra cavity does not contain photons, the input single photon will be reflected; when the cavity contains one photon, the full transmission of the input single photon can be obtained. In the off-resonance case, the single-photon transport can also be controlled by the parameters of the cavity. Therefore, we show that single-photon transport can be controlled by an extra cavity field.

Yan, Wei-Bin; Fan, Heng

2014-11-01

317

Selective Excitation and Detection of Spin States in a Single Nanowire  

E-print Network

with linewidths as narrow as about 30 µeV, we are able to resolve individual spin states at magnetic fields quantum dots where cleanliness is measured as a narrow line width in the optical spectra. Initial optical for measuring spin states above a magnetic field of 1 T. We grow InAs0.25P0.75 quantum dots embedded in In

318

The NV center as a quantum actuator: time-optimal control of nuclear spins  

E-print Network

Indirect control of qubits by a quantum actuator has been proposed as an appealing strategy to manipulate qubits that couple only weakly to external fields. While universal quantum control can be easily achieved when the actuator-qubit coupling is anisotropic, the efficiency of this approach is less clear. Here we analyze the time-efficiency of the quantum actuator control. We describe a strategy to find time-optimal control sequence by the quantum actuator and compare their gate times with direct driving, identifying regimes where the actuator control performs faster. As an example, we focus on a specific implementation based on the Nitrogen-Vacancy center electronic spin in diamond (the actuator) and nearby carbon-13 nuclear spins (the qubits).

Clarice D. Aiello; Paola Cappellaro

2014-10-21

319

A Comparison Study of Magnetic Bearing Controllers for a Fully Suspended Dynamic Spin Rig  

NASA Technical Reports Server (NTRS)

NASA Glenn Research Center (GRC) has developed a fully suspended magnetic bearing system for the Dynamic Spin Rig (DSR) that is used to perform vibration tests of turbomachinery blades and components under spinning conditions in a vacuum. Two heteropolar radial magnetic bearings and a thrust bearing and the associated control system were integrated into the DSR to provide noncontact magnetic suspension and mechanical excitation of the 35 lb vertical rotor with blades to induce turbomachinery blade vibration. A simple proportional-integral-derivative (PID) controller with a special feature for multidirectional radial excitation worked very well to both support and shake the shaft with blades. However, more advanced controllers were developed and successfully tested to determine the optimal controller in terms of sensor and processing noise reduction, smaller rotor orbits, and energy savings for the system. The test results of a variety of controllers we demonstrated up to the rig's maximum allowable speed of 10,000 rpm are shown.

Choi, Benjamin; Johnson, Dexter; Morrison, Carlos; Mehmed, Oral; Huff, Dennis (Technical Monitor)

2002-01-01

320

The artificial satellite observation chronograph controlled by single chip microcomputer.  

NASA Astrophysics Data System (ADS)

The instrument specifications, hardware structure, software design, and other characteristics of the chronograph mounting on a theodolite used for artificial satellite observation are presented. The instrument is a real time control system with a single chip microcomputer.

Pan, Guangrong; Tan, Jufan; Ding, Yuanjun

1991-06-01

321

Generator for single bubbles of controllable size C. D. Ohla)  

E-print Network

. A single bubble is generated by injecting a short burst of gas into a liquid channel flow. The radius Figure 1 sketches the bubble generator. The pressure for the gas (Pgas) injection upper valve in Fig. 1Generator for single bubbles of controllable size C. D. Ohla) Department of Applied Physics, TU

Ohl, Claus-Dieter

322

Storing quantum information in XXZ spin rings with periodically time-controlled interactions  

Microsoft Academic Search

We introduce a general scheme to realize massive quantum memories in simple systems of interacting qubits. Such systems are described by spin rings with XXZ intersite couplings of suitably time-periodically controlled amplitudes. We show that initially localized excitations undergo perfect periodic revivals, allowing for the simultaneous storage of arbitrary sets of different local states. This novel approach to the problem

S. M. Giampaolo; F. Illuminati; G. Mazzarella

2005-01-01

323

MEETING SCIENCE REQUIREMENTS FOR ATTITUDE DETERMINATION AND CONTROL IN A LOW-POWER, SPINNING NANOSATELLITE  

Microsoft Academic Search

this paper describes the attitude determination and control system for a nanosatellite (30 kg), using geomagnetic field data and solar panels as sun sensors, applied to a spinning nanosatellite (Penn State University's LionSat). LionSat will map plasma densities in the ram and wake of the vehicle's path, using two hybrid plasma probes that rotate with the spacecraft. Attitude will be

Phill-Sun Hur; Robert G. Melton; David B. Spencer

324

Zeno and Anti-Zeno Polarization Control of Spin Ensembles by Induced Dephasing Gonzalo A. A lvarez,1,2  

E-print Network

Zeno and Anti-Zeno Polarization Control of Spin Ensembles by Induced Dephasing Gonzalo A. A´ lvarez (polarization) control of qubits entangled with multiple spins, using induced dephasing in nuclear magnetic the bath-induced upward and downward transition rates in the qubit. By contrast, less frequent measurements

Frydman, Lucio

325

PUBLISHED ONLINE: 21 OCTOBER 2012 | DOI: 10.1038/NPHYS2457 Production of spin-controlled rare isotope beams  

E-print Network

-controlled rare isotope beams Yuichi Ichikawa1 * , Hideki Ueno1 , Yuji Ishii2 , Takeshi Furukawa3 , Akihiro propose a method for controlling spin in a system of rare isotopes which takes advantage of the mechanism% was achieved for the spin of a rare isotope 32 Al. The figure of merit for the present method was found

Loss, Daniel

326

Magnetoelectric control of spin-chiral ferroelectric domains in a triangular lattice antiferromagnet  

Microsoft Academic Search

We have grown single crystals of a triangular lattice antiferromagnet (TLA), CuCrO2 , and investigated the correlation between magnetic and dielectric properties. Two magnetic phase transitions are observed at TN2≈24.2K and TN1≈23.6K . It was found that ferroelectric polarization along the triangular lattice plane develops at TN1 , suggesting that the system undergoes a transition into an out-of-plane 120° spin-chiral

Kenta Kimura; Hiroyuki Nakamura; Tsuyoshi Kimura

2008-01-01

327

Counterfactual distributed controlled-phase gate for quantum-dot spin qubits in double-sided optical microcavities  

NASA Astrophysics Data System (ADS)

The existing distributed quantum gates required physical particles to be transmitted between two distant nodes in the quantum network. We here demonstrate the possibility to implement distributed quantum computation without transmitting any particles. We propose a scheme for a distributed controlled-phase gate between two distant quantum-dot electron-spin qubits in optical microcavities. The two quantum-dot-microcavity systems are linked by a nested Michelson-type interferometer. A single photon acting as ancillary resource is sent in the interferometer to complete the distributed controlled-phase gate, but it never enters the transmission channel between the two nodes. Moreover, we numerically analyze the effect of experimental imperfections and show that the present scheme can be implemented with high fidelity in the ideal asymptotic limit. The scheme provides further evidence of quantum counterfactuality and opens promising possibilities for distributed quantum computation.

Guo, Qi; Cheng, Liu-Yong; Chen, Li; Wang, Hong-Fu; Zhang, Shou

2014-10-01

328

When a single hole aligns several spins: Double exchange in organic systems  

NASA Astrophysics Data System (ADS)

The double exchange is a well-known and technically important phenomenon in solid state physics. Ionizing a system composed of two antiferromagnetically coupled high-spin units, the ground state of which is a singlet state, may actually produce a high-spin ground state. This work illustrates the possible occurrence of such a phenomenon in organic chemistry. The here-considered high-spin units are triangulenes, the ground state of which is a triplet. Bridging two of them through a benzene ring produces a molecular architecture of singlet ground state. A careful exploitation of a series of unrestricted density functional calculations enables one to avoid spin contamination in the treatment of the doublet states and shows that under ionization the system becomes of quartet multiplicity in its ground state. The possibility to align more than three spins from conjugated hydrocarbon polyradicals is explored, considering partially hydrogenated triangulenes. A dramatic example shows that ionization of a singlet ground state molecule may generate a decuplet.

Trinquier, Georges; Chilkuri, Vijay Gopal; Malrieu, Jean-Paul

2014-05-01

329

Attitude determination, control and navigation of a spinning satellite  

Microsoft Academic Search

This study examines the concepts of autonomous spacecraft navigation, attitude determination and control. Navigation in orbit requires a minimum of two independent horizon to celestial body measurements that are correlated with time to establish a position in orbit over the earth. Sensor systems applicable for navigation are combinations of one sun sensor, star sensor, horizon sensor and clock, or star

J. J. Rodden

1983-01-01

330

Environment-assisted quantum control of a solid-state spin via coherent dark states  

NASA Astrophysics Data System (ADS)

Understanding the interplay between a quantum system and its environment lies at the heart of quantum science and its applications. So far most efforts have focused on circumventing decoherence induced by the environment by either protecting the system from the associated noise or by manipulating the environment directly. Recently, parallel efforts using the environment as a resource have emerged, which could enable dissipation-driven quantum computation and coupling of distant quantum bits. Here, we realize the optical control of a semiconductor quantum-dot spin by relying on its interaction with an adiabatically evolving spin environment. The emergence of hyperfine-induced, quasi-static optical selection rules enables the optical generation of coherent spin dark states without an external magnetic field. We show that the phase and amplitude of the lasers implement multi-axis manipulation of the basis spanned by the dark and bright states, enabling control via projection into a spin-superposition state. Our approach can be extended, within the scope of quantum control and feedback, to other systems interacting with an adiabatically evolving environment.

Hansom, Jack; Schulte, Carsten H. H.; Le Gall, Claire; Matthiesen, Clemens; Clarke, Edmund; Hugues, Maxime; Taylor, Jacob M.; Atatüre, Mete

2014-10-01

331

Environment-assisted quantum control of a solid-state spin via coherent dark states  

E-print Network

Understanding the interplay between a quantum system and its environment lies at the heart of quantum science and its applications. To-date most efforts have focused on circumventing decoherence induced by the environment by either protecting the system from the associated noise or by manipulating the environment directly. Recently, parallel efforts using the environment as a resource have emerged, which could enable dissipation-driven quantum computation and coupling of distant quantum bits. Here, we realize the optical control of a semiconductor quantum-dot spin by relying on its interaction with an adiabatically evolving spin environment. The emergence of hyperfine-induced, quasi-static optical selection rules enables the optical generation of coherent spin dark states without an external magnetic field. We show that the phase and amplitude of the lasers implement multi-axis manipulation of the basis spanned by the dark and bright states, enabling control via projection into a spin-superposition state. Our approach can be extended, within the scope of quantum control and feedback, to other systems interacting with an adiabatically evolving environment.

Jack Hansom; Carsten H. H. Schulte; Claire Le Gall; Clemens Matthiesen; Edmund Clarke; Maxime Hugues; Jacob M. Taylor; Mete Atatüre

2014-08-06

332

Precise measuring mass and spin of dark matter particles at ILC via singularities in the single lepton energy spectrum  

NASA Astrophysics Data System (ADS)

We consider models, in which stability of Dark Matter particles D is ensured by the conservation of the new quantum number, called D-parity here. Our models contain also charged D-odd particle D ±. We propose method for precision measuring masses and spin of D-particles via the study of energy distribution of single lepton ( e or ?) in the process e + e - ? D + D - ? DDW + W - with the observable state dijet + ? ( or e) + nothing. It is shown that this distribution has kinematically determined singular points (upper edge and kinks or peak). Measuring of their positions allow to determine precisely masses of D and D ±. After this, even a rough measuring of corresponding cross section allows to determine the spin of D particles.

Ginzburg, I. F.

2014-01-01

333

Single-spin asymmetries in semi-inclusive deep-inelastic scattering on a transversely polarized hydrogen target.  

PubMed

Single-spin asymmetries for semi-inclusive electroproduction of charged pions in deep-inelastic scattering of positrons are measured for the first time with transverse target polarization. The asymmetry depends on the azimuthal angles of both the pion (phi) and the target spin axis (phi(S)) about the virtual-photon direction and relative to the lepton scattering plane. The extracted Fourier component sin((phi+phi(S))(pi)(UT) is a signal of the previously unmeasured quark transversity distribution, in conjunction with the Collins fragmentation function, also unknown. The component sin((phi-phi(S)(pi)(UT) arises from a correlation between the transverse polarization of the target nucleon and the intrinsic transverse momentum of quarks, as represented by the previously unmeasured Sivers distribution function. Evidence for both signals is observed, but the Sivers asymmetry may be affected by exclusive vector meson production. PMID:15698069

Airapetian, A; Akopov, N; Akopov, Z; Amarian, M; Andrus, A; Aschenauer, E C; Augustyniak, W; Avakian, R; Avetissian, A; Avetissian, E; Bacchetta, A; Bailey, P; Balin, D; Beckmann, M; Belostotski, S; Bianchi, N; Blok, H P; Böttcher, H; Borissov, A; Borysenko, A; Bouwhuis, M; Brüll, A; Bryzgalov, V; Capitani, G P; Cappiluppi, M; Chen, T; Ciullo, G; Contalbrigo, M; Dalpiaz, P F; Leo, R De; Demey, M; Nardo, L De; Sanctis, E De; Devitsin, E; Nezza, P Di; Düren, M; Ehrenfried, M; Elalaoui-Moulay, A; Elbakian, G; Ellinghaus, F; Elschenbroich, U; Fabbri, R; Fantoni, A; Fechtchenko, A; Felawka, L; Frullani, S; Gapienko, G; Gapienko, V; Garibaldi, F; Garrow, K; Gavrilov, G; Gharibyan, V; Grebeniouk, O; Gregor, I M; Hadjidakis, C; Hafidi, K; Hartig, M; Hasch, D; Henoch, M; Hesselink, W H A; Hillenbrand, A; Hoek, M; Holler, Y; Hommez, B; Hristova, I; Iarygin, G; Ilyichev, A; Ivanilov, A; Izotov, A; Jackson, H E; Jgoun, A; Kaiser, R; Kinney, E; Kisselev, A; Kobayashi, T; Kopytin, M; Korotkov, V; Kozlov, V; Krauss, B; Krivokhijine, V G; Lagamba, L; Lapikás, L; Laziev, A; Lenisa, P; Liebing, P; Linden-Levy, L A; Lorenzon, W; Lu, H; Lu, J; Lu, S; Ma, B-Q; Maiheu, B; Makins, N C R; Mao, Y; Marianski, B; Marukyan, H; Masoli, F; Mexner, V; Meyners, N; Michler, T; Mikloukho, O; Miller, C A; Miyachi, Y; Muccifora, V; Nagaitsev, A; Nappi, E; Naryshkin, Y; Nass, A; Negodaev, M; Nowak, W-D; Oganessyan, K; Ohsuga, H; Osborne, A; Pickert, N; Potterveld, D H; Raithel, M; Reggiani, D; Reimer, P E; Reischl, A; Reolon, A R; Riedl, C; Rith, K; Rosner, G; Rostomyan, A; Rubacek, L; Rubin, J; Ryckbosch, D; Salomatin, Y; Sanjiev, I; Savin, I; Schäfer, A; Schill, C; Schnell, G; Schüler, K P; Seele, J; Seidl, R; Seitz, B; Shanidze, R; Shearer, C; Shibata, T-A; Shutov, V; Sinram, K; Sommer, W; Stancari, M; Statera, M; Steffens, E; Steijger, J J M; Stenzel, H; Stewart, J; Stinzing, F; Tait, P; Tanaka, H; Taroian, S; Tchuiko, B; Terkulov, A; Trzcinski, A; Tytgat, M; Vandenbroucke, A; van der Nat, P B; van der Steenhoven, G; van Haarlem, Y; Vetterli, M C; Vikhrov, V; Vincter, M G; Vogel, C; Volmer, J; Wang, S; Wendland, J; Wilbert, J; Smit, G Ybeles; Ye, Y; Ye, Z; Yen, S; Zihlmann, B; Zupranski, P

2005-01-14

334

A DQ synchronous frame controller for single-phase inverters  

Microsoft Academic Search

This paper deals with design of a synchronous frame control strategy for single-phase inverter-based islanded distributed generation (DG) systems. Although, implementation of these regulators requires a minimum of two independent phases in the system, the required orthogonal phase is generated through the use of a first order all pass filter (APF). The essence of the proposed control strategy is to

Saeed Golestan; Mohammad Monfared; Josep M. Guerrero; Mahmood Joorabian

2011-01-01

335

Room temperature coherent control of defect spin qubits in silicon carbide.  

PubMed

Electronic spins in semiconductors have been used extensively to explore the limits of external control over quantum mechanical phenomena. A long-standing goal of this research has been to identify or develop robust quantum systems that can be easily manipulated, for future use in advanced information and communication technologies. Recently, a point defect in diamond known as the nitrogen-vacancy centre has attracted a great deal of interest because it possesses an atomic-scale electronic spin state that can be used as an individually addressable, solid-state quantum bit (qubit), even at room temperature. These exceptional quantum properties have motivated efforts to identify similar defects in other semiconductors, as they may offer an expanded range of functionality not available to the diamond nitrogen-vacancy centre. Notably, several defects in silicon carbide (SiC) have been suggested as good candidates for exploration, owing to a combination of computational predictions and magnetic resonance data. Here we demonstrate that several defect spin states in the 4H polytype of SiC (4H-SiC) can be optically addressed and coherently controlled in the time domain at temperatures ranging from 20 to 300 kelvin. Using optical and microwave techniques similar to those used with diamond nitrogen-vacancy qubits, we study the spin-1 ground state of each of four inequivalent forms of the neutral carbon-silicon divacancy, as well as a pair of defect spin states of unidentified origin. These defects are optically active near telecommunication wavelengths, and are found in a host material for which there already exist industrial-scale crystal growth and advanced microfabrication techniques. In addition, they possess desirable spin coherence properties that are comparable to those of the diamond nitrogen-vacancy centre. This makes them promising candidates for various photonic, spintronic and quantum information applications that merge quantum degrees of freedom with classical electronic and optical technologies. PMID:22051676

Koehl, William F; Buckley, Bob B; Heremans, F Joseph; Calusine, Greg; Awschalom, David D

2011-11-01

336

Controlling the relaxation of propagating spin waves in yttrium iron garnet/Pt bilayers with thermal gradients  

NASA Astrophysics Data System (ADS)

The spin currents generated by thermal gradients through the spin Seebeck effect (SSE) are usually detected by the voltage generated in a normal metal by means of the inverse spin Hall effect. Here, we present a detailed account of an experimental investigation of the action of spin currents due to SSE on the relaxation rate of spin waves. Propagating spin-wave packets with a frequency in the range of 1-2 GHz are launched in film strips of single-crystal yttrium iron garnet, Y3Fe5O12 (YIG) while a thermal gradient is applied across the thickness in the so-called longitudinal SSE configuration. No change in damping is observed in bare YIG films. However, if the YIG film is covered with an ultrathin platinum layer, we observe a striking change in the amplitude of the detected spin-wave pulses. Depending on the sign of the gradient, the spin-wave relaxation rate can be increased or decreased, leading in the latter case to an apparent amplification. The change in the relaxation rate is attributed to the action of a spin current generated in the YIG film by the SSE while the role of the Pt layer is to supply or absorb the flow of spins.

Cunha, R. O.; Padrón-Hernández, E.; Azevedo, A.; Rezende, S. M.

2013-05-01

337

Simultaneous control of two four-wave-mixing fields via atomic spin coherence  

NASA Astrophysics Data System (ADS)

We report the experimental observation of simultaneous control of two four-wave-mixing fields via an induced atomic spin coherence formed by a Raman process with one coupling field and one probe field in a triple-?-type Rb85 atomic system. It is shown that by changing the atomic density, intensity, or detuning of the coupling field, the relative intensities of the two four-wave-mixing fields can be manipulated. This behavior can be explained as the change in the spin coherence for varying the coupling field intensity and the large difference in the attenuation coefficients of the two produced four-wave-mixing fields for varying the atomic density. This controlling process may find applications in coherent control of nonlinear optical processes and quantum information processing.

Yang, Xihua; Sheng, Jiteng; Khadka, Utsab; Xiao, Min

2011-06-01

338

Transport through single-level systems: Spin dynamics in the nonadiabatic regime  

NASA Astrophysics Data System (ADS)

We investigate the Fano-Anderson model coupled to a large ensemble of spins under the influence of an external magnetic field. The interaction between the two spin systems is treated within a mean-field approach, and we assume an anisotropic coupling between these two systems. By using a nonadiabatic approach, we make no further approximations in the theoretical description of our system, apart from the semiclassical treatment. Therewith, we can include the short-time dynamics as well as the broadening of the energy levels arising due to the coupling to the external electronic reservoirs. We study the spin dynamics in the regime of low and high bias. For the infinite bias case, we compare our results to those obtained from a simpler rate equation approach, where higher-order transitions are neglected. We show that these higher-order terms are important in the range of low magnetic field. Additionally, we analyze extensively the finite bias regime with methods from nonlinear dynamics, and we discuss the possibility of switching of the large spin.

Metelmann, A.; Brandes, T.

2012-12-01

339

Development of Electro-Mechanical Spinning for Controlled Deposition of Carbon Nanofibers  

NASA Astrophysics Data System (ADS)

In the past few decades the fields of nanotechnology and miniaturized devices had an exponentially growth of interest in academic and research environment, leading to breakthroughs discoveries that are envisioned to have a profound impact on our economy and society in the near future. Recently, the focus is moving toward the development of technologies that enable the production of micro- /nano-devices on a larger scale and at lower costs. Among the different micro- /nano-devices manufacturing challenges, in this dissertation the aim is to reliably fabricate suspend carbon micro- /nano-fibers between two carbon electrode walls in a way that can be mass produced at relatively low cost. The first part of this thesis provides an in depth overview of current methods used for the fabrication of carbon based micro devices (C-MEMS) and of electrospinning, a manufacturing technology that emerges as a simple and inexpensive approach to produce nanofibers. Electro-Mechanical Spinning (EMS) has been developed from electrospinning and optimized for the production of suspended carbon nanofibers, aiming to achieve greater deposition control at the single nanofiber level, while maintaining the low cost of electrospinning. After the successful development of EMS, the so fabricated carbon micro- /nano-fibers have been characterized, first from the electrical point of view, then from the mechanical one. The electrical characterization involves conductivity measurements of fibers with respect of different and controllable manufacturing processes steps. Variations of those manufacturing parameters have been proven to be capable of tailoring the carbon structure and, therefore, the conductivity of the fibers within a desired range. Further investigation regarding the electrical properties was also conducted to prevent (or control) current induced fiber breakdown. Finally, the Young's modulus of those fibers was investigated and observed to be dependent on the fibers thickness. Similarly to conductivity, variations in Young's modulus are also related to formation of a different carbon structure when fibers diameter is below certain values. In conclusion, appropriate combinations of EMS and C-MEMS processes were proven to be capable of fabricating controllable suspended carbon nanofibers with tuned conductivity and Young's modulus properties.

Canton, Giulia

340

Correlation control for pure and efficiently generated heralded single photons  

E-print Network

We present a detailed study on the properties of single photons generated by spontaneous parametric down conversion (SPDC) when both the spectral and spatial degrees of freedom are controlled by means of filters. Our results show that it is possible to obtain pure heralded single photons with high heralding efficiency despite the use of filters. Moreover, we report an asymmetry on the single photon properties exhibited in type-II SPDC sources that depends on choosing the signal or the idler photon as the heralding one.

Jefferson Flórez; Omar Calderón; Clara I. Osorio; Alejandra Valencia

2014-10-07

341

Cotunneling spectroscopy and the properties of excited-state spin manifolds of Mn12 single molecule magnets  

NASA Astrophysics Data System (ADS)

We study charge transport through single molecule magnet (SMM) junctions in the cotunneling regime as a tool for investigating the properties of the excited-state manifolds of neutral Mn12 SMs. This study is motivated by a recent transport experiment [S. Kahle et al., Nano Lett. 12, 518 (2012), 10.1021/nl204141z] that probed the details of the magnetic and electronic structure of Mn12 SMMs beyond the ground-state spin manifold. A giant spin Hamiltonian and master equation approach is used to explore theoretically the cotunneling transport through Mn12-Ac SMM junctions. We identify SMM transitions that can account for both the strong and weak features of the experimental differential conductance spectra. We find the experimental results to imply that the excited spin-state manifolds of the neutral SMM have either different anisotropy constants or different g factors in comparison with its ground-state manifold. However, the latter scenario accounts best for the experimental data.

Rostamzadeh Renani, Fatemeh; Kirczenow, George

2014-10-01

342

Spatial light modulator-controlled alignment and spinning of birefringent particles optically trapped in an array.  

PubMed

We demonstrate the use of a phase-only liquid-crystal spatial light modulator (SLM) for polarization-controlled rotation and alignment of an array of optically trapped birefringent particles. A collimated beam incident upon a two-dimensional lenslet array yields multiple foci, scaled to produce optical gradient traps with efficient three-dimensional trapping potentials. The state of polarization of each trapping beam is encoded by the SLM, which acts as a matrix of wave plates with computer-controlled phase retardations. Control of the rotation frequency and alignment direction of the particles is achieved by the transfer of tunable photon spin angular momentum. PMID:12962388

Eriksen, René L; Rodrigo, Peter J; Daria, Vincent R; Glückstad, Jesper

2003-09-01

343

Observation of zero-point quantum fluctuations of a single-molecule magnet through the relaxation of its nuclear spin bath.  

PubMed

A single-molecule magnet placed in a magnetic field perpendicular to its anisotropy axis can be truncated to an effective two-level system, with easily tunable energy splitting. The quantum coherence of the molecular spin is largely determined by the dynamics of the surrounding nuclear spin bath. Here we report the measurement of the nuclear spin-lattice relaxation rate 1/T1n in a single crystal of the single-molecule magnet Mn12-ac, at T ? 30 mK in perpendicular fields B? up to 9 T. The relaxation channel at B ? 0 is dominated by incoherent quantum tunneling of the Mn12-ac spin S, aided by the nuclear bath itself. However for B?>5 T we observe an increase of 1/T1n by several orders of magnitude up to the highest field, despite the fact that the molecular spin is in its quantum mechanical ground state. This striking observation is a consequence of the zero-point quantum fluctuations of S, which allow it to mediate the transfer of energy from the excited nuclear spin bath to the crystal lattice at much higher rates. Our experiment highlights the importance of quantum fluctuations in the interaction between an "effective two-level system" and its surrounding spin bath. PMID:24702408

Morello, A; Millán, A; de Jongh, L J

2014-03-21

344

Analytical and Numerical Solution of a Sub-Riemannian Optimal Control Problem with Applications to Quantum Spin Systems  

Microsoft Academic Search

Experiments in nuclear magnetic resonance (NMR) spectroscopy and NMR quantum computing require control of ensembles of quantum mechanical systems. The controlled transfer of coherence along a one-dimensional chain of spin systems plays a key role in NMR spectroscopy of proteins, and spin chains have also been proposed for NMR quantum information processing. The problem of time-optimal or energy-optimal control of

Amit K. Sanyal; Christopher Moseley; Anthony Bloch

2009-01-01

345

Rashba Spin-Orbit Anisotropy and the Electric Field Control of Magnetism  

PubMed Central

The control of the magnetism of ultra-thin ferromagnetic layers using an electric field, rather than a current, has many potential technologically important applications. It is usually insisted that such control occurs via an electric field induced surface charge doping that modifies the magnetic anisotropy. However, it remains the case that a number of key experiments cannot be understood within such a scenario. Much studied is the spin-splitting of the conduction electrons of non-magnetic metals or semi-conductors due to the Rashba spin-orbit coupling. This reflects a large surface electric field. For a magnet, this same splitting is modified by the exchange field resulting in a large magnetic anisotropy energy via the Dzyaloshinskii-Moriya mechanism. This different, yet traditional, path to an electrically induced anisotropy energy can explain the electric field, thickness, and material dependence reported in many experiments. PMID:24531151

Barnes, Stewart E.; Ieda, Jun'ichi; Maekawa, Sadamichi

2014-01-01

346

Ab initio design of spin-filters using single organic molecules  

NASA Astrophysics Data System (ADS)

The possibility of using the electron`s spin in addition to its charge as information carrying physical quantity in future electronic devices has stimulated extensive experimental and theoretical studies over the last decade. The design of nanoscale spintronic elements in multifunctional devices relies on a clear understanding of the physics at electrode-molecule interfaces and in particular, the functionality of specific molecules in a given organic-metal surface environment. Using density functional theory simulations we have performed systematic studies on several organic molecules (e.g. benzene, cyclopentadiene radical and cyclooctatetraene) adsorbed on a ferromagnetic surface (e.g. 2ML Fe on W(110)). We show how the magnetic information can be transmitted through an interface formed even by a non-magnetic molecule adsorbed on the ferromagnetic metal surfaces. Furthermore, our calculations demonstrate that as for other aromatic molecules on metal surfaces [1], taking into account the van der Waals interaction is essential to precisely follow the charge transfer at the interface and the formation of spin- split molecule-metal hybrid states. Our results demonstrate that even in the case of non-magnetic molecules, a molecule-electrode system can act as an efficient molecular spin-filter if the electrode is magnetic. [1] N. Atodiresei et al. Phys. Rev. Lett. 102, (136809) (2009).

Atodiresei, Nicolae; Lazic, Predrag; Caciuc, Vasile; Blügel, Stefan

2010-03-01

347

Control of crisis-induced intermittency in the dynamics of a kicked, damped spin  

NASA Astrophysics Data System (ADS)

A method of controlling the intermittent behavior induced by a crisis is applied to a model of a periodically kicked, damped spin. Using small, occasional changes of a parameter, one can make the system remain on a former attractor, enlarged or destroyed by a crisis. The amplitude of the changes grows linearly with the distance from the crisis point, and the frequency of interventions scales as the inverse of the characteristic time of the intermittency.

Kacperski, Krzysztof; Ho?yst, Janusz A.

1997-05-01

348

Technology spin-off from space power automation to terrestrial electrical power distribution control and operation  

NASA Astrophysics Data System (ADS)

Areas which hold potential for technology spin-off from space power automation into terrestrial electrical power distribution control and automation are investigated. Areas touched upon include load management, loss reduction, trend analysis, energy storage, and fault diagnosis and analysis with expert systems. A brief overview of terrestrial electric power technology and automation in terrestrial distribution is provided. Power handling capabilities, hardware, loads, and goals of terrestrial and space systems are compared.

Callis, C. T.; Broadwater, R. P.; Chandrasekaran, A.

349

Exploiting environmental torques for attitude control and determination of spin stabilized satellites  

NASA Technical Reports Server (NTRS)

Design techniques are presented which exploit environmental torques for attitude control and determination of spin stabilized satellites. The techniques are applicable to satellite missions where the dominant environmental torques are well understood and lend themselves to accurate analytical modeling. The techniques were applied to the Particles and Fields subsatellites of the Apollo 15 and 16 spacecraft and the flight results show good agreement with the attitude determination estimates obtained.

Gluck, R.

1974-01-01

350

The Sivers effect and the Single Spin Asymmetry A_N in p(transv. pol.) p --> h X processes  

SciTech Connect

The single spin asymmetry A_N, for large P_T single inclusive particle production in p(transv. pol.) p collisions, is considered within a generalised parton model and a transverse momentum dependent factorisation scheme. The focus is on the Sivers effect and the study of its potential contribution to A_N, based on a careful analysis of the Sivers functions extracted from azimuthal asymmetries in semi-inclusive deep inelastic scattering processes. It is found that such Sivers functions could explain most features of the A_N data, including some recent STAR results which show the persistence of a non zero A_N up to surprisingly large P_T values.

Anselmino, Mauro [TORINO, INFN-TORINO; Boglione, Mariaelena [TORINO, INFN-TORINO; D'Alesio, Umberto [INFN Cagliari; Melis, Stefano [TORINO, INFN-TORINO; Murgia, Francesco [INFN Cagliari; Prokudin, Alexei [JLAB

2013-09-01

351

Sivers effect and the single spin asymmetry A_N in p(transv. pol.) p --> h X processes  

E-print Network

The single spin asymmetry A_N, for large P_T single inclusive particle production in p(transv. pol.) p collisions, is considered within a generalised parton model and a transverse momentum dependent factorisation scheme. The focus is on the Sivers effect and the study of its potential contribution to A_N, based on a careful analysis of the Sivers functions extracted from azimuthal asymmetries in semi-inclusive deep inelastic scattering processes. It is found that such Sivers functions could explain most features of the A_N data, including some recent STAR results which show the persistence of a non zero A_N up to surprisingly large P_T values.

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

2013-04-29

352

Single-Shot Time Domain Studies of Spin-Torque-Driven Switching and Precession in Magnetic Tunnel Junctions  

NASA Astrophysics Data System (ADS)

We present single-shot time domain resistance measurements of spin-transfer-driven dynamics in CoFeB/MgO/CoFeB tunnel junctions. In the regime of thermally-activated current-driven switching, we have sufficient sensitivity to resolve the pattern of resistance oscillations caused by the magnetic dynamics leading up to switching. When an in-plane hard-axis magnetic field is applied, within a short interval before the switching instant the resistance oscillations show a steadily-increasing amplitude, qualitatively consistent with expectations for large-angle precession in a simple macrospin model, although the oscillation amplitude can vary between individual switching events. Coherent large-angle oscillations are generally absent in the case of an applied field along the easy axis, which can be attributed to the differences in the precession axis and switching barriers as well as effects of thermal fluctuations. We will also report results of single-shot transport measurements in the regime of spin-torque-driven steady-state precession.

Cui, Yong-Tao; Buhrman, Robert A.; Ralph, Daniel C.; Mauri, Daniele; Katine, Jordan A.

2009-03-01

353

Magnetophoretic circuits for digital control of single particles and cells.  

PubMed

The ability to manipulate small fluid droplets, colloidal particles and single cells with the precision and parallelization of modern-day computer hardware has profound applications for biochemical detection, gene sequencing, chemical synthesis and highly parallel analysis of single cells. Drawing inspiration from general circuit theory and magnetic bubble technology, here we demonstrate a class of integrated circuits for executing sequential and parallel, timed operations on an ensemble of single particles and cells. The integrated circuits are constructed from lithographically defined, overlaid patterns of magnetic film and current lines. The magnetic patterns passively control particles similar to electrical conductors, diodes and capacitors. The current lines actively switch particles between different tracks similar to gated electrical transistors. When combined into arrays and driven by a rotating magnetic field clock, these integrated circuits have general multiplexing properties and enable the precise control of magnetizable objects. PMID:24828763

Lim, Byeonghwa; Reddy, Venu; Hu, XingHao; Kim, KunWoo; Jadhav, Mital; Abedini-Nassab, Roozbeh; Noh, Young-Woock; Lim, Yong Taik; Yellen, Benjamin B; Kim, CheolGi

2014-01-01

354

A sliding mode controller in single phase voltage source inverters  

Microsoft Academic Search

This paper deals with a sliding mode controller for a single phase inverter used in UPS applications. The proposed system provides overload and short circuit protection. It can operate in constant or variable frequency. The use of a reduced order observer eliminates the requirement of the load current measurement and improves the noise immunity. Experimental results obtained in laboratory are

H. Pinheiro; A. S. Martins; J. R. Pinheiro

1994-01-01

355

Lag Synchronization of Coullet System via a Single Control  

NASA Astrophysics Data System (ADS)

In this paper, based on Lyapunov stability theory, a novel scheme is proposed to explore the lag synchronization of Coullet system. Via back stepping method, the scheme needs only a single controller and the sufficient condition of synchronization is derived. To illustrate the effectiveness of the proposed scheme, some numerical simulations are presented.

Shi, Xue-Rong; Wang, Zuolei

2014-11-01

356

Redundant single gimbal control moment gyroscope singularity analysis  

Microsoft Academic Search

The robotic manipulator is proposed as the mechanical analog to single gimbal control moment gyroscope systems, and it is shown that both systems share similar difficulties with singular configurations. This analogy is used to group gimbal angles corresponding to any momentum state into different families. The singularity problem associated with these systems is examined in detail. In particular, a method

Nazareth S. Bedrossian; Joseph Paradiso; Edward V. Bergmann; Derek Rowell

1990-01-01

357

Active Control for Single Camera SLAM Teresa Vidal-Calleja  

E-print Network

Active Control for Single Camera SLAM Teresa Vidal-Calleja Institut de Rob`otica i Inform-held camera perform- ing SLAM at video rate with generic 6DOF motion. The aim is to optimise both to bearing-only SLAM. Moreover, orientation changes are determined by maximising the trace of the Fisher

Murray, David

358

Single-chip microcomputer control of the inverter by the magnetic flux control PWM method [machine control  

Microsoft Academic Search

Single-chip microcomputer control of a pulsewidth-modulated (PWM) inverter for motor drive applications is presented. The PWM pattern generation and the system control of the inverter are achieved by software of the 8-bit single-chip microcomputer. The single-chip microcomputer has a low processing speed and small memory capacity, disadvantages that can be overcome by the magnetic flux control PWM method. The PWM

M. Morimoto; S. Sato; K. Sumito; K. Oshitani

1989-01-01

359

Control Study for Five-Axis Dynamic Spin Rig Using Magnetic Bearings  

NASA Technical Reports Server (NTRS)

The NASA Glenn Research Center (GRC) has developed a magnetic bearing system for the Dynamic Spin Rig (DSR) with a fully suspended shaft that is used to perform vibration tests of turbomachinery blades and components under spinning conditions in a vacuum. Two heteropolar radial magnetic bearings and a thrust magnetic bearing and the associated control system were integrated into the DSR to provide magnetic excitation as well as non-contact mag- netic suspension of a 15.88 kg (35 lb) vertical rotor with blades to induce turbomachinery blade vibration. For rotor levitation, a proportional-integral-derivative (PID) controller with a special feature for multidirectional radial excitation worked well to both support and shake the shaft with blades. However, more advanced controllers were developed and successfully tested to determine the optimal controller in terms of sensor and processing noise reduction, smaller rotor orbits, more blade vibration amplitude, and energy savings for the system. The test results of a variety of controllers that were demonstrated up to 10.000 rpm are shown. Furthermore, rotor excitation operation and conceptual study of active blade vibration control are addressed.

Choi, Benjamin; Johnson, Dexter; Provenza, Andrew; Morrison, Carlos; Montague, Gerald

2003-01-01

360

Control Study for Five-axis Dynamic Spin Rig Using Magnetic Bearings  

NASA Technical Reports Server (NTRS)

The NASA Glenn Research Center (GRC) has developed a magnetic bearing system for the Dynamic Spin Rig (DSR) with a fully suspended shaft that is used to perform vibration tests of turbomachinery blades and components under spinning conditions in a vacuum. Two heteropolar radial magnetic bearings and a thrust magnetic bearing and the associated control system were integrated into the DSR to provide magnetic excitation as well as non-contact mag- netic suspension of a 15.88 kg (35 lb) vertical rotor with blades to induce turbomachinery blade vibration. For rotor levitation, a proportional-integral-derivative (PID) controller with a special feature for multidirectional radial excitation worked well to both support and shake the shaft with blades. However, more advanced controllers were developed and successfully tested to determine the optimal controller in terms of sensor and processing noise reduction, smaller rotor orbits, more blade vibration amplitude, and energy savings for the system. The test results of a variety of controllers that were demonstrated up to 10.000 rpm are shown. Furthermore, rotor excitation operation and conceptual study of active blade vibration control are addressed.

Choi, Benjamin; Johnson, Dexter; Provenza, Andrew; Morrison, Carlos; Montague, Gerald

2003-01-01

361

A 3% Measurement of the Beam Normal Single Spin Asymmetry in Forward Angle Elastic Electron-Proton Scattering using the Qweak Setup  

SciTech Connect

The beam normal single spin asymmetry generated in the scattering of transversely polarized electrons from unpolarized nucleons is an observable of the imaginary part of the two-photon exchange process. Moreover, it is a potential source of false asymmetry in parity violating electron scattering experiments. The Q{sub weak} experiment uses parity violating electron scattering to make a direct measurement of the weak charge of the proton. The targeted 4% measurement of the weak charge of the proton probes for parity violating new physics beyond the Standard Model. The beam normal single spin asymmetry at Q{sub weak} kinematics is at least three orders of magnitude larger than 5 ppb precision of the parity violating asymmetry. To better understand this parity conserving background, the Q{sub weak} Collaboration has performed elastic scattering measurements with fully transversely polarized electron beam on the proton and aluminum. This dissertation presents the analysis of the 3% measurement (1.3% statistical and 2.6% systematic) of beam normal single spin asymmetry in electronproton scattering at a Q2 of 0.025 (GeV/c)2. It is the most precise existing measurement of beam normal single spin asymmetry available at the time. A measurement of this precision helps to improve the theoretical models on beam normal single spin asymmetry and thereby our understanding of the doubly virtual Compton scattering process.

Waidyawansa, Dinayadura Buddhini [OHIO U.

2013-08-01

362

Quantum Interference Control of Ballistic Pure Spin Currents in Semiconductors Martin J. Stevens and Arthur L. Smirl*  

E-print Network

Quantum Interference Control of Ballistic Pure Spin Currents in Semiconductors Martin J. Stevens, University of Toronto, 60 St. George Street, Toronto, Ontario, Canada M5S 1A7 (Received 19 November 2002

Van Driel, Henry M.

363

Cryogenic High-Frequency Readout and Control Platform for Spin Qubits  

E-print Network

We have developed a cryogenic platform for the control and readout of spin qubits that comprises a high density of dc and radio frequency sample interconnects based on a set of coupled printed circuit boards. The modular setup incorporates 24 filtered dc lines, 14 control and readout lines with bandwidth from dc to above 6 GHz, and 2 microwave connections for excitation to 40 GHz. We report the performance of this platform, including signal integrity and crosstalk measurements and discuss design criteria for constructing sample interconnect technology needed for multi-qubit devices.

J. I. Colless; D. J. Reilly

2011-11-28

364

Mass property control of a spin stabilized spacecraft with restrictive mission and weight constraints  

NASA Technical Reports Server (NTRS)

In the primary experiment of the spin stabilized San Marco D/L spacecraft, the drag effects on a light spherical shell coupled to a relatively massive center body will be measured. To achieve the precise mass property control, the centroids of both the shell and the center body must coincide with each other and with the center of pressure of the shell. Precise spin balancing is needed for launch and orbital stability, and the deployable antennas need accurate alignment. Corrective measures, developed after the preliminary mass measurements showed flaws in the mass property control, are described in detail. Inertia booms and a yo-yo despin system were developed as add-on units, spin balance measurements about all three geometric axes were used to define weight minimized correction within the outer shell envelope, and boom tip mass differentials were optimized for the most favorable inertia ratio margin achievable within the mission weight constraints. The weight versus orbital lifetime trade-offs were also considered.

Lang, W. E.; Ardvini, C.

1985-01-01

365

Self-oscillation of standing spin wave in ring resonator with proportional-integral-derivative control  

NASA Astrophysics Data System (ADS)

We report on numerical analysis on self-oscillation of standing spin wave excited in a nanostructured active ring resonator, consists of a ferromagnetic nanowire with perpendicular anisotropy. The confined resonant modes are along the nanowire length. A positive feedback with proportional-integral-derivative gain control was adopted in the active ring. Stable excitation of the 1st order standing spin wave has been demonstrated with micromagnetic simulations, taking into account the thermal effect with a random field model. The stationary standing spin wave with a pre-determined set variable of precession amplitude was attained within 20 ns by optimizing the proportional-integral-derivative gain control parameters. The result indicates that a monochromatic oscillation frequency fosc is extracted from the initial thermal fluctuation state and selectively amplified with the positive feedback loop. The obtained fosc value of 5.22 GHz practically agrees with the theoretical prediction from dispersion relation of the magneto static forward volume wave. It was also confirmed that the fosc change due to the temperature rise can be compensated with an external perpendicular bias field Hb. The observed quick compensation time with an order of nano second suggests the fast operation speed in the practical device application.

Peng, B.; Urazuka, Y.; Chen, H.; Oyabu, S.; Otsuki, H.; Tanaka, T.; Matsuyama, K.

2014-05-01

366

Theory of Spin-Orbit Enhanced Electric-Field Control of Magnetism in Multiferroic BiFeO3  

NASA Astrophysics Data System (ADS)

We present a microscopic theory that shows the importance of spin-orbit coupling in perovskite compounds with heavy ions. In BiFeO3 (BFO) the spin-orbit coupling at the bismuth ion sites results in a special kind of magnetic anisotropy that is linear in the applied E field. This interaction can convert the cycloid ground state into a homogeneous antiferromagnet, with a weak ferromagnetic moment whose orientation can be controlled by the E-field direction. Remarkably, the E-field control of magnetism occurs without poling the ferroelectric moment, providing a pathway for reduced energy dissipation in spin-based devices made of insulators.

de Sousa, Rogério; Allen, Marc; Cazayous, Maximilien

2013-06-01

367

Highly optimized simulations on single- and multi-GPU systems of 3D Ising spin glass  

E-print Network

We present a highly optimized implementation of a Monte Carlo (MC) simulator for the three-dimensional Ising spin-glass model with bimodal disorder, i.e., the 3D Edwards-Anderson model running on CUDA enabled GPUs. Multi-GPU systems exchange data by means of the Message Passing Interface (MPI). The chosen MC dynamics is the classic Metropolis one, which is purely dissipative, since the aim was the study of the critical off-equilibrium relaxation of the system. We focused on the following issues: i) the implementation of efficient access patterns for nearest neighbours in a cubic stencil and for lagged-Fibonacci-like pseudo-Random Numbers Generators (PRNGs); ii) a novel implementation of the asynchronous multispin-coding Metropolis MC step allowing to store one spin per bit and iii) a multi-GPU version based on a combination of MPI and CUDA streams. We highlight how cubic stencils and PRNGs are two subjects of very general interest because of their widespread use in many simulation codes. Our code best perform...

Lulli, Matteo; Parisi, Giorgio

2014-01-01

368

Paramagnetic Spin Correlations in CaFe2As2 Single Crystals  

SciTech Connect

Magnetic correlations in the paramagnetic phase of CaFe2As2(TN=172 K) have been examined by means of inelastic neutron scattering from 180 K ( 1.05TN) up to 300 K (1.8TN). Despite the first-order nature of the magnetic ordering, strong but short-ranged antiferromagnetic (AFM) correlations are clearly observed. These correlations, which consist of quasielastic scattering centered at the wave vector QAFM of the low-temperature AFM structure, are observed up to the highest measured temperature of 300 K and at high energy transfer ( >60 meV). The L dependence of the scattering implies rather weak interlayer coupling in the tetragonal c direction corresponding to nearly two-dimensional fluctuations in the (ab) plane. The spin correlation lengths within the Fe layer are found to be anisotropic, consistent with underlying fluctuations of the AFM stripe structure. Similar to the cobalt-doped superconducting BaFe2As2 compounds, these experimental features can be adequately reproduced by a scattering model that describes short-ranged and anisotropic spin correlations with overdamped dynamics.

Omar Diallo, Souleymane [ORNL; Pratt, Daniel [Ames Laboratory and Iowa State University; Fernandes, Rafael [Ames Laboratory and Iowa State University; Tian, Wei [Ames Laboratory and Iowa State University; Zarestky, J. L. [Ames Laboratory and Iowa State University; Lumsden, Mark D [ORNL; Perring, T. G. [ISIS Facility, Rutherford Appleton Laboratory; Broholm, C. [Johns Hopkins University; Ni, Ni [Ames Laboratory and Iowa State University; Budko, S L [Ames Laboratory and Iowa State University; Canfield, Paul [Ames Laboratory and Iowa State University; Li, Haifeng [Ames Laboratory and Iowa State University; Vaknin, D [Ames Laboratory and Iowa State University; Kreyssig, A. [Ames Laboratory and Iowa State University; Goldman, A. I. [Ames Laboratory and Iowa State University; Mcqueeney, R J [Ames Laboratory and Iowa State University

2010-01-01

369

Single-cell resolution fluorescence imaging of circadian rhythms detected with a Nipkow spinning disk confocal system.  

PubMed

Single-point laser scanning confocal imaging produces signals with high spatial resolution in living organisms. However, photo-induced toxicity, bleaching, and focus drift remain challenges, especially when recording over several days for monitoring circadian rhythms. Bioluminescence imaging is a tool widely used for this purpose, and does not cause photo-induced difficulties. However, bioluminescence signals are dimmer than fluorescence signals, and are potentially affected by levels of cofactors, including ATP, O(2), and the substrate, luciferin. Here we describe a novel time-lapse confocal imaging technique to monitor circadian rhythms in living tissues. The imaging system comprises a multipoint scanning Nipkow spinning disk confocal unit and a high-sensitivity EM-CCD camera mounted on an inverted microscope with auto-focusing function. Brain slices of the suprachiasmatic nucleus (SCN), the central circadian clock, were prepared from transgenic mice expressing a clock gene, Period 1 (Per1), and fluorescence reporter protein (Per1::d2EGFP). The SCN slices were cut out together with membrane, flipped over, and transferred to the collagen-coated glass dishes to obtain signals with a high signal-to-noise ratio and to minimize focus drift. The imaging technique and improved culture method enabled us to monitor the circadian rhythm of Per1::d2EGFP from optically confirmed single SCN neurons without noticeable photo-induced effects or focus drift. Using recombinant adeno-associated virus carrying a genetically encoded calcium indicator, we also monitored calcium circadian rhythms at a single-cell level in a large population of SCN neurons. Thus, the Nipkow spinning disk confocal imaging system developed here facilitates long-term visualization of circadian rhythms in living cells. PMID:22480987

Enoki, Ryosuke; Ono, Daisuke; Hasan, Mazahir T; Honma, Sato; Honma, Ken-Ichi

2012-05-30

370

Towards an explanation of transverse single-spin asymmetries in proton-proton collisions: the role of fragmentation in collinear factorization  

E-print Network

We study the transverse single-spin asymmetry for single-hadron production in proton-proton collisions within the framework of collinear twist-3 factorization in Quantum Chromodynamics. By taking into account the contribution due to parton fragmentation we obtain a very good description of all high transverse-momentum data for neutral and charged pion production from the Relativistic Heavy Ion Collider. Our study may provide the crucial step towards a final solution to the longstanding problem of what causes transverse single-spin asymmetries in hadronic collisions within Quantum Chromodynamics. We show for the first time that, in a conceptually satisfactory framework, it is possible to simultaneously describe spin/azimuthal asymmetries in proton-proton collisions, semi-inclusive deep-inelastic scattering, and electron-positron annihilation.

Kanazawa, K; Metz, A; Pitonyak, D

2014-01-01

371

Towards an explanation of transverse single-spin asymmetries in proton-proton collisions: the role of fragmentation in collinear factorization  

E-print Network

We study the transverse single-spin asymmetry for single-hadron production in proton-proton collisions within the framework of collinear twist-3 factorization in Quantum Chromodynamics. By taking into account the contribution due to parton fragmentation we obtain a very good description of all high transverse-momentum data for neutral and charged pion production from the Relativistic Heavy Ion Collider. Our study may provide the crucial step towards a final solution to the longstanding problem of what causes transverse single-spin asymmetries in hadronic collisions within Quantum Chromodynamics. We show for the first time that it is possible to simultaneously describe spin/azimuthal asymmetries in proton-proton collisions, semi-inclusive deep-inelastic scattering, and electron-positron annihilation by using collinear twist-3 factorization in the first process along with transverse momentum dependent functions extracted from the latter two reactions.

K. Kanazawa; Y. Koike; A. Metz; D. Pitonyak

2014-04-03

372

The problem of how single electron or hole "central" spins interact with a nuclear spin bath is essential for understanding decoherence  

E-print Network

on passively detecting the spectrum of intrinsic random spin fluctuations while in thermal equilibrium (i noise indicates long (400 ns) spin correlation times at a zero magnetic field that increase to 5 µs and dynamical responses (exponential, power-law, Gaussian, etc.). As an alternative to conventional pump

373

Numrical simulation of a spin interferometer based on a single square loop with Rashba interaction  

NASA Astrophysics Data System (ADS)

We numerically calculate the transverse conductance as a function of magnetic field in two models. One is an exact 1D model and the other is a quasi 1D square loop system which is similar to the experimental setup by Koga et. al. From the conductance curves, we employ FFT (Fast Fourier transform) and IFFT (inverse Fast Fourier transform) to extract separately the oscillatory part of conductance whose period correspond to the magnetic flux quanta (AB oscillation) and half quanta (AAS oscillation). We show that the spin precession angle ? is modulated by the Rashba interaction strength. From the curves about the amplitude of AB or AAS oscillations at B=0 versus ?, we find that the node positions of ? in the exact 1D model fits well with previous theoretical calculations, but there are some deviations for the quasi 1D model.

Zhu, Zhenyue; Sun, Qing-Feng; Chen, Bin; Xie, Xin-Cheng

2006-03-01

374

Refining the Spin Hamiltonian in the Spin-1/2 Kagome Lattice Antiferromagnet ZnCu[subscript 3](OH)[subscript 6]Cl[subscript 2] Using Single Crystals  

E-print Network

We report thermodynamic measurements of the S=1/2 kagome lattice antiferromagnet ZnCu[subscript 3](OH)[subscript 6]Cl[subscript 2], a promising candidate system with a spin-liquid ground state. Using single crystal samples, ...

Han, Tianheng

375

A single-phase controlled-current PWM rectifier  

Microsoft Academic Search

The analysis and test results are given for an experimental single-phase controlled-current PWM (pulse-width-modulated) rectifier that operates at unity power factor with near sinusoidal current waveform and that has power reversal capability. The twice-line-frequency AC power is identified as a source of voltage harmonics in the DC link. The harmonics enter into the voltage regulation feedback loop to distort the

O. Stihi; Boon-Teck Ooi

1988-01-01

376

Single-electron devices via controlled assembly of designed nanoparticles  

Microsoft Academic Search

Single-electron transistors (SET) rely for their functionality on extreme control of lithography and lateral positioning as well as of properties of the building blocks from which the devices are built. By an aerosol-based nanoparticle fabrication we can prepare nanocrystals down to sub-10nm dimensions with metallic or semiconducting character, as well as having a core + shell design for definition of

Tobias Junno; Martin H. Magnusson; Sven-Bertil Carlsson; Knut Deppert; Jan-Olle Malm; Lars Montelius; Lars Samuelson

1999-01-01

377

Single event effects in pulse width modulation controllers  

SciTech Connect

SEE testing was performed on pulse width modulation (PWM) controllers which are commonly used in switching mode power supply systems. The devices are designed using both Set-Reset (SR) flip-flops and Toggle (T) flip-flops which are vulnerable to single event upset (SEU) in a radiation environment. Depending on the implementation of the different devices the effect can be significant in spaceflight hardware.

Penzin, S.H.; Crain, W.R.; Crawford, K.B.; Hansel, S.J.; Kirshman, J.F.; Koga, R. [Aerospace Corp., El Segundo, CA (United States)] [Aerospace Corp., El Segundo, CA (United States)

1996-12-01

378

X-ray absorption spectroscopic investigation of the spin-transition character in a series of single-site perturbed iron(II) complexes.  

PubMed

Select ferrous spin-transition complexes with the pentadentate ligand 2,6-bis(bis(2-pyridyl)methoxymethane)pyridine (PY5) were examined using variable-temperature solution solid-state magnetic susceptibility, crystallography, X-ray absorption spectroscopy (XAS), and UV/vis absorption spectroscopy. Altering the single exogeneous ligand, X, of [Fe(PY5)(X)]n)+ is sufficient to change the spin-state of the complexes. When X is the weak-field ligand Cl-, the resultant Fe complex is high-spin from 4 to 300 K, whereas the stronger-field ligand MeCN generates a low-spin complex over this temperature range. With intermediate-strength exogenous ligands (X = N3-, MeOH), the complexes undergo a spin-transition. [Fe(PY5)(N3)]+, as a crystalline solid, transitions gradually from a high-spin to a low-spin complex as the temperature is decreased, as evidenced by X-ray crystallography and solid-state magnetic susceptibility measurements. The spin-transition is also evident from changes in the pre-edge and EXAFS regions of the XAS Fe K-edge spectra on a ground crystalline sample. The spin-transition observed with [Fe(PY5)(MeOH)]2+ appears abrupt by solid-state magnetic susceptibility measurements, but gradual by XAS analysis, differences attributed to sample preparation. This research highlights the strengths of XAS in determining the electronic and geometric structure of such spin-transition complexes and underscores the importance of identical sample preparation in the investigation of these physical properties. PMID:15732962

Rudd, Deanne Jackson; Goldsmith, Christian R; Cole, Adam P; Stack, T Daniel P; Hodgson, Keith O; Hedman, Britt

2005-03-01

379

Single-atom quantum control of macroscopic mechanical oscillators  

NASA Astrophysics Data System (ADS)

We investigate a hybrid electromechanical system consisting of a pair of charged macroscopic mechanical oscillators coupled to a small ensemble of Rydberg atoms. The resonant dipole-dipole coupling between an internal atomic Rydberg transition and the mechanics allows cooling to its motional ground state with a single atom despite the considerable mass imbalance between the two subsystems. We show that the rich electronic spectrum of Rydberg atoms, combined with their high degree of optical control, paves the way towards implementing various quantum-control protocols for the mechanical oscillators.

Bariani, F.; Otterbach, J.; Tan, Huatang; Meystre, P.

2014-01-01

380

Uncovering many-body correlations in nanoscale nuclear spin baths by central spin decoherence  

NASA Astrophysics Data System (ADS)

Central spin decoherence caused by nuclear spin baths is often a critical issue in various quantum computing schemes, and it has also been used for sensing single-nuclear spins. Recent theoretical studies suggest that central spin decoherence can act as a probe of many-body physics in spin baths; however, identification and detection of many-body correlations of nuclear spins in nanoscale systems are highly challenging. Here, taking a phosphorus donor electron spin in a 29Si nuclear spin bath as our model system, we discover both theoretically and experimentally that many-body correlations in nanoscale nuclear spin baths produce identifiable signatures in decoherence of the central spin under multiple-pulse dynamical decoupling control. We demonstrate that under control by an odd or even number of pulses, the central spin decoherence is principally caused by second- or fourth-order nuclear spin correlations, respectively. This study marks an important step toward studying many-body physics using spin qubits.

Ma, Wen-Long; Wolfowicz, Gary; Zhao, Nan; Li, Shu-Shen; Morton, John J. L.; Liu, Ren-Bao

2014-09-01

381

Uncovering many-body correlations in nanoscale nuclear spin baths by central spin decoherence  

PubMed Central

Central spin decoherence caused by nuclear spin baths is often a critical issue in various quantum computing schemes, and it has also been used for sensing single-nuclear spins. Recent theoretical studies suggest that central spin decoherence can act as a probe of many-body physics in spin baths; however, identification and detection of many-body correlations of nuclear spins in nanoscale systems are highly challenging. Here, taking a phosphorus donor electron spin in a 29Si nuclear spin bath as our model system, we discover both theoretically and experimentally that many-body correlations in nanoscale nuclear spin baths produce identifiable signatures in decoherence of the central spin under multiple-pulse dynamical decoupling control. We demonstrate that under control by an odd or even number of pulses, the central spin decoherence is principally caused by second- or fourth-order nuclear spin correlations, respectively. This study marks an important step toward studying many-body physics using spin qubits. PMID:25205440

Ma, Wen-Long; Wolfowicz, Gary; Zhao, Nan; Li, Shu-Shen; Morton, John J.L.; Liu, Ren-Bao

2014-01-01

382

Single-particle structures, high-spin isomers, and a strongly coupled band in odd-odd Sb120  

NASA Astrophysics Data System (ADS)

Excited states in Sb120 have been investigated using the Cd116(Li7,3n)Sb120 reaction at a beam energy of 34 MeV. A total of 15 new ? rays were added into the level scheme of Sb120. Most of the observed single-particle states can be interpreted in terms of weak coupling of the odd proton and odd neutron to an excited Sn118 core involving either vibrational states or broken neutron pairs. The previously known strongly coupled rotational band based on the ?g9/2-1??h11/2 configuration has been extended up to the (15-) state. The configuration-fixed constrained triaxial relativistic mean-field approaches and the particle rotor model are employed to discuss the high-spin isomers and strongly coupled rotational band, respectively.

Liu, L.; Wang, S. Y.; Chen, Z. Q.; Liu, C.; Qi, B.; Sun, D. P.; Wang, S.; An, Q.; Xu, C. J.; Zhang, P.; Li, Z. Q.; Niu, C. Y.; Wu, X. G.; Li, G. S.; He, C. Y.; Zheng, Y.; Li, C. B.; Yao, S. H.; Hu, S. P.; Li, H. W.; Liu, J. J.; Wang, J. L.

2014-07-01

383

Single Spin Asymmetries of Inclusive Hadrons Produced in Electron Scattering from a Transversely Polarized 3He Target  

We report the first measurement of target single-spin asymmetries (AN) in the inclusive hadron production reaction, e + 3He??h+X, using a transversely polarized 3 He target. The experiment was conducted at Jefferson Lab in Hall A using a 5.9-GeV electron beam. Three types of hadrons (?±, K± and proton) were detected in the transverse hadron momentum range 0.54 T F for pions was -0.29 FF+ and K+. A negative asymmetry is observed for ??. The magnitudes of the asymmetries follow |A? ?|? +|K +|. The K? and proton asymmetries are consistent with zero within the experimental uncertainties. The ?+ and ?? asymmetries measured for the 3He target and extracted for neutrons are opposite in sign with a small increase observed as a function of pT.

Allada, Kalyan; Zhao, Yongxiang; Aniol, Konrad; Annand, John; Averett, Todd; Benmokhtar, Fatiha; Bertozzi, William; Bradshaw, Peter; Bosted, Peter; Camsonne, Alexandre; Canan, Mustafa; Cates, Gordon; Chen, Chunhua; Chen, Jian-Ping; Chen, Wei; Chirapatpimol, Khem; Chudakov, Eugene; Cisbani, Evaristo; Cornejo, Juan; Cusanno, Francesco; Dalton, Mark; Deconinck, Wouter; De, Cornelis; , Jager; De, Raffaele; , Leo; Deng, Xiaoyan; Deur, Alexandre; Ding, Huaibo; Dolph, Peter; Dutta, Chiranjib; Dutta, Dipangkar; Elfassi, Lamiaa; Frullani, Salvatore; Gao, Haiyan; Garibaldi, Franco; Gaskell, David; Gilad, Shalev; Gilman, Ronald; Glamazdin, Oleksandr; Golge, Serkan; Guo, Lei; Hamilton, David; Hansen, Jens-Ole; Higinbotham, Douglas; Holmstrom, Timothy; Huang, Jin; Huang, Min; Ibrahim, Hassan; Iodice, Mauro; Jin, Ge; Jones, Mark; Katich, Joseph; Kelleher, Aidan; Kim, Wooyoung; Kolarkar, Ameya; Korsch, Wolfgang; LeRose, John; Li, Xiaomei; Li, Y; Lindgren, Richard; Liyanage, Nilanga; Long, Elena; Lu, Hai-jiang; Margaziotis, Demetrius; Markowitz, Pete; Marrone, Stefano; McNulty, Dustin; Meziani, Zein-Eddine; Michaels, Robert; Moffit, Bryan; Munoz, Carlos; , Camacho; Nanda, Sirish; Narayan, Amrendra; Nelyubin, Vladimir; Norum, Blaine; Oh, Yongseok; Osipenko, Mikhail; Parno, Diana; Peng, Jen-chieh; Phillips, Sarah; Posik, Matthew; Puckett, Andrew; Qian, Xin; Qiang, Yi; Rakhman, Abdurahim; Ransome, Ronald; Riordan, Seamus; Saha, Arunava; Sawatzky, Bradley; Schulte, Elaine; Shahinyan, Albert; Hashemi, Mitra; , Shabestari; Sirca, Simon; Stepanyan, Stepan; Subedi, Ramesh; Sulkosky, Vincent; Tang, Liguang; Tobias, William; Urciuoli, Guido; Vilardi, Ignazio; Wang, Kebin; Wang, Y; Wojtsekhowski, Bogdan; Yan, X; Yao, Huan; Ye, Yunxiu; Ye, Z; Yuan, Lulin; Zhan, Xiaohui; Zhang, Yawei; Zhang, Yi; Zhao, Bo; Zheng, Xiaochao; Zhu, Lingyan; Zhu, Xiaofeng; Zong, Xing

2014-04-01

384

Entangled states of trapped ions allow measuring the magnetic field gradient produced by a single atomic spin  

NASA Astrophysics Data System (ADS)

We propose detecting the magnetic field gradient produced by the magnetic dipole moment of a single atom by using ions in an entangled state trapped a few ?m from the dipole. This requires measuring magnetic field gradients of order 10-13 tesla/?m. We discuss applications in determining magnetic moments of a wide variety of ion species, for investigating the magnetic substructure of ions with level structures that are not suitable for laser cooling and detection, and for studying exotic or rare ions, and molecular ions. The scheme may also be used for measuring spin imbalances of neutral atoms or atomic ensembles trapped by optical dipole forces. As the proposed method relies on techniques that are well established in ion trap quantum information processing, it is within reach of current technology.

Schmidt-Kaler, F.; Gerritsma, R.

2012-09-01

385

A coherent beam splitter for electronic spin states.  

PubMed

Rapid coherent control of electron spin states is required for implementation of a spin-based quantum processor. We demonstrated coherent control of electronic spin states in a double quantum dot by sweeping an initially prepared spin-singlet state through a singlet-triplet anticrossing in the energy-level spectrum. The anticrossing serves as a beam splitter for the incoming spin-singlet state. When performed within the spin-dephasing time, consecutive crossings through the beam splitter result in coherent quantum oscillations between the singlet state and a triplet state. The all-electrical method for quantum control relies on electron-nuclear spin coupling and drives single-electron spin rotations on nanosecond time scales. PMID:20133567

Petta, J R; Lu, H; Gossard, A C

2010-02-01

386

Lattice-solvent controlled spin transitions in iron(II) complexes.  

PubMed

A series of spin transition (ST) iron(II) compounds of the type [FeII2](X)2.{S}2 (where is 4'-(4'''-cyanophenyl)-1,2':6'1''-bispyrazolylpyridine, X=ClO4- or BF4-, and S is acetonitrile) was synthesized and magnetically investigated. The effects of the removal of the lattice-solvent molecules and of their different positions relative to the iron(II) cations on the ST process were investigated. Crystallization yields orange block (A.{S}2) crystals of the composition [FeII()2](ClO4)2.{S}2, and two polymorphic compounds of the stoichiometry [FeII()2](BF4)2.{S}2 as red coffin (B.{S}2) and orange block (C.{S}2) crystals. The Fe-N bond distances of A.{S}2 (from 1.921(9) to 1.992(3) A; at 150 K), B.{S}2 (from 1.943(2) to 2.017(2) A; at 180 K) and C.{S}2 (from 1.883(3) to 1.962(3) A; at 180 K) indicate low spin (LS) states of the respective iron(II) ions. Notably, the observed small difference in the Fe-N distances at 180 K for the two polymorphs B.{S}2and C.{S}2 are due to different positions of the acetonitrile molecules in the crystal lattices and illustrate the sensitivity of the spin transition properties on lattice-solvent effects. Variable-temperature single crystal X-ray studies display single-crystal thermochroism (red (LS)<-->orange (HS)) for A.{S}2 and B.{S}2 and ca. 3.6% decrease in the unit cell volume of A.{S}2 from 4403 A3 at 300 K to 4278 A3 at 150 K. The temperature dependent magnetic susceptibilities of A.{S}2 and B.{S}2 demonstrate systematic increase of the spin transition temperatures (T1/2) and continuous decreases of the hysteresis loop width (DeltaT1/2) upon slow lattice-solvent exclusion. PMID:17680043

Rajadurai, Chandrasekar; Qu, Zhirong; Fuhr, Olaf; Gopalan, Balaji; Kruk, Robert; Ghafari, Mohammed; Ruben, Mario

2007-08-28

387

Analytic Theory and Control of the Motion of Spinning Rigid Bodies  

NASA Technical Reports Server (NTRS)

Numerical simulations are often resorted to, in order to understand the attitude response and control characteristics of a rigid body. However, this approach in performing sensitivity and/or error analyses may be prohibitively expensive and time consuming, especially when a large number of problem parameters are involved. Thus, there is an important role for analytical models in obtaining an understanding of the complex dynamical behavior. In this dissertation, new analytic solutions are derived for the complete attitude motion of spinning rigid bodies, under minimal assumptions. Hence, we obtain the most general solutions reported in the literature so far. Specifically, large external torques and large asymmetries are included in the problem statement. Moreover, problems involving large angular excursions are treated in detail. A new tractable formulation of the kinematics is introduced which proves to be extremely helpful in the search for analytic solutions of the attitude history of such kinds of problems. The main utility of the new formulation becomes apparent however, when searching for feedback control laws for stabilization and/or reorientation of spinning spacecraft. This is an inherently nonlinear problem, where standard linear control techniques fail. We derive a class of control laws for spin axis stabilization of symmetric spacecraft using only two pairs of gas jet actuators. Practically, this could correspond to a spacecraft operating in failure mode, for example. Theoretically, it is also an important control problem which, because of its difficulty, has received little, if any, attention in the literature. The proposed control laws are especially simple and elegant. A feedback control law that achieves arbitrary reorientation of the spacecraft is also derived, using ideas from invariant manifold theory. The significance of this research is twofold. First, it provides a deeper understanding of the fundamental behavior of rigid bodies subject to body-fixed torques. Assessment of the analytic solutions reveals that they are very accurate; for symmetric bodies the solutions of Euler's equations of motion are, in fact, exact. Second, the results of this research have a fundamental impact on practical scientific and mechanical applications in terms of the analysis and control of all finite-sized rigid bodies ranging from nanomachines to very large bodies, both man made and natural. After all, Euler's equations of motion apply to all physical bodies, barring only the extreme limits of quantum mechanics and relativity.

Tsiotras, Panagiotis

1993-01-01

388

Electron Spin Resonance of a Gamma-Irradiated Single Crystal of Barbituric Acid Dihydrate  

Microsoft Academic Search

Free radicals produced in single crystals of barbituric acid dihydrate by ionizing radiation have been identified by ESR spectroscopy and the parameters of the Hamiltonian describing the free radicals have been determined. The stable radical observed at room temperature is formed by loss of a hydrogen atom from C(5) of the original molecule, thus leaving an unpaired electron mainly in

William Bernhard; Wallace Snipes

1966-01-01

389

Mapping of single-site magnetic anisotropy tensors in weakly coupled spin clusters by torque magnetometry.  

PubMed

Single-crystal torque magnetometry performed on weakly-coupled polynuclear systems provides access to a complete description of single-site anisotropy tensors. Variable-temperature, variable-field torque magnetometry was used to investigate triiron(III) complex [Fe3La(tea)2(dpm)6] (Fe3La), a lanthanum(III)-centred variant of tetrairon(III) single molecule magnets (Fe4) (H3tea = triethanolamine, Hdpm = dipivaloylmethane). Due to the presence of the diamagnetic lanthanoid, magnetic interactions among iron(III) ions (si = 5/2) are very weak (<0.1 cm(?1)) and the magnetic response of Fe3La is predominantly determined by single-site anisotropies. The local anisotropy tensors were found to have Di > 0 and to be quasi-axial with |Ei/Di| ~ 0.05. Their hard axes form an angle of approximately 70° with the threefold molecular axis, which therefore corresponds to an easy magnetic direction for the molecule. The resulting picture was supported by a High Frequency EPR investigation and by DFT calculations. Our study confirms that the array of peripheral iron(III) centres provides substantially noncollinear anisotropy contributions to the ground state of Fe4 complexes, which are of current interest in molecular magnetism and spintronics. PMID:25014192

Rigamonti, Luca; Cornia, Andrea; Nava, Andrea; Perfetti, Mauro; Boulon, Marie-Emmanuelle; Barra, Anne-Laure; Zhong, Xiaoliang; Park, Kyungwha; Sessoli, Roberta

2014-08-28

390

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

E-print Network

]. Such an environment is provided, for instance, by ligand groups holding such atoms together in a single magnetic mole a few magnetic atoms in an anisotropic environment respond to an electron current [1 magnetic atoms embedded in a molecular network on an insulating surface in an STM setup [4,5]. Such systems

391

Valley-spin blockade and spin resonance in carbon nanotubes  

NASA Astrophysics Data System (ADS)

The manipulation and readout of spin qubits in quantum dots have been successfully achieved using Pauli blockade, which forbids transitions between spin-triplet and spin-singlet states. Compared with spin qubits realized in III-V materials, group IV materials such as silicon and carbon are attractive for this application because of their low decoherence rates (nuclei with zero spins). However, valley degeneracies in the electronic band structure of these materials combined with Coulomb interactions reduce the energy difference between the blocked and unblocked states, significantly weakening the selection rules for Pauli blockade. Recent demonstrations of spin qubits in silicon devices have required strain and spatial confinement to lift the valley degeneracy. In carbon nanotubes, Pauli blockade can be observed by lifting valley degeneracy through disorder, but this makes the confinement potential difficult to control. To achieve Pauli blockade in low-disorder nanotubes, quantum dots have to be made ultrasmall, which is incompatible with conventional fabrication methods. Here, we exploit the bandgap of low-disorder nanotubes to demonstrate robust Pauli blockade based on both valley and spin selection rules. We use a novel stamping technique to create a bent nanotube, in which single-electron spin resonance is detected using the blockade. Our results indicate the feasibility of valley-spin qubits in carbon nanotubes.

Pei, Fei; Laird, Edward A.; Steele, Gary A.; Kouwenhoven, Leo P.

2012-10-01

392

RBS1, an RNA Binding Protein, Interacts with SPIN1 and Is Involved in Flowering Time Control in Rice  

PubMed Central

The rice U-box/ARM E3 ubiquitin ligase SPL11 negatively regulates programmed cell death (PCD) and disease resistance, and controls flowering time through interacting with the novel RNA/DNA binding KH domain protein SPIN1. Overexpression of Spin1 causes late flowering in transgenic rice under short-day (SD) and long-day (LD) conditions. In this study, we characterized the function of the RNA-binding and SPIN1-interacting 1 (RBS1) protein in flowering time regulation. Rbs1was identified in a yeast-two-hybrid screen using the full-length Spin1 cDNA as a bait and encodes an RNA binding protein with three RNA recognition motifs. The protein binds RNA in vitro and interacts with SPIN1 in the nucleus. Rbs1 overexpression causes delayed flowering under SD and LD conditions in rice. Expression analyses of flowering marker genes show that Rbs1 overexpression represses the expression of Hd3a under SD and LD conditions. Rbs1 is upregulated in both Spin1 overexpression plants and in the spl11 mutant. Interestingly, Spin1 expression is increased but Spl11 expression is repressed in the Rbs1 overexpression plants. Western blot analysis revealed that the SPIN1 protein level is increased in the Rbs1 overexpression plants and that the RBS1 protein level is also up-regulated in the Spin1 overexpression plants. These results suggest that RBS1 is a new negative regulator of flowering time that itself is positively regulated by SPIN1 but negatively regulated by SPL11 in rice. PMID:24498057

Cai, Yuhui; Vega-Sanchez, Miguel E.; Park, Chan Ho; Bellizzi, Maria; Guo, Zejian; Wang, Guo-Liang

2014-01-01

393

A comparative EPR study of high- and low-spin Mn 6 single-molecule magnets  

Microsoft Academic Search

We report detailed numerical and spectroscopic studies of two complexes from a family of recently discovered Mn6III single-molecule magnets (SMMs) with large barriers to magnetization reversal. These complexes consist of a pair of Mn3III triangles with a ferromagnetic interaction between the triangles. Recent studies have shown that the exchange interactions within the triangular Mn3III units can be switched from antiferromagnetic

Saiti Datta; Erica Bolin; Ross Inglis; Constantinos J. Milios; Euan K. Brechin; Stephen Hill

2009-01-01

394

Measurements of Single and Double Spin Asymmetry in \\textit{pp} Elastic Scattering in the CNI Region with Polarized Hydrogen Gas Jet Target  

E-print Network

Precise measurements of the single spin asymmetry, $A_N$ and the double spin asymmetry, $A_{NN}$, in proton-proton (\\textit{pp}) elastic scattering in the region of four-momentum transfer squared $0.001 hydrogen gas jet target and the RHIC polarized proton beam at 24 GeV/$c$ and 100 GeV/$c$. The polarized gaseous proton target allowed us to achieve the measurement of $A_{NN}$ in the CNI region for the first time. Our results of $A_N$ and $A_{NN}$ provide significant constraints to determine the magnitude of poorly known hadronic single and double spin-flip amplitudes at this energy.

H. Okada; I. Alekseev; A. Bravar; G. Bunce; S. Dhawan; K. O. Eyser; R. Gill; W. Haeberli; H. Huang; O. Jinnouchi; Y. Makdishi; I. Nakagawa; A. Nass; N. Saito; E. Stephenson; D. Sviridia; T. Wise; J. Wood; A. Zelenski

2007-04-08

395

Spin-stripe density varies linearly with the hole content in single-layer Bi2+xSr2-xCuO6+y cuprate superconductors.  

PubMed

We have performed inelastic neutron scattering measurements on the single-layer cuprate Bi(2+x) Sr(2-x) CuO(6+y) (Bi2201) with x = 0.2, 0.3, 0.4, and 0.5, a doping range that spans the spin-glass to superconducting phase boundary. The doping evolution of low energy spin fluctuations (11 spin correlations between Bi2201 and the prototypical single-layer system La(2-x) Sr(x)CuO(4) are discussed. PMID:23383829

Enoki, M; Fujita, M; Nishizaki, T; Iikubo, S; Singh, D K; Chang, S; Tranquada, J M; Yamada, K

2013-01-01

396

Controllable orientation of single silver nanowire using two fiber probes  

PubMed Central

We report a strategy for realizing precise orientation of single silver nanowire using two fiber probes. By launching a laser of 980?nm wavelength into the two fibers, single silver nanowire with a diameter of 600?nm and a length of 6.5??m suspended in water was trapped and rotated by optical torque resulting from its interaction with optical fields outputted from the fiber probes. Angular orientation of the nanowire was controlled by varying the relative distance between the two fiber probes. The angular stiffness, which refers to the stability of orientation, was estimated to be on the order of 10?19?J/rad2·mW. The experiments were interpreted by theoretical analysis. PMID:24496474

Xu, Xiaohao; Cheng, Chang; Xin, Hongbao; Lei, Hongxiang; Li, Baojun

2014-01-01

397

Magnetic field controlled FZ single crystal growth of intermetallic compounds  

NASA Astrophysics Data System (ADS)

Intermetallic rare-earth-transition-metal compounds with their coexistence of magnetic ordering and superconductivity are still of great scientific interest. The crystal growth of bulk single crystals is very often unsuccessful due to an unfavorable solid-liquid interface geometry enclosing concave fringes. The aim of the work is the contactless control of heat and material transport during floating-zone single crystal growth of intermetallic compounds. This control is provided by a tailored design of the electromagnetic field and the resulting electromagnetically driven convection. Numerical simulations for the determination of the electromagnetic field configuration induced by the RF heater coil and the solution of the coupled heat and hydrodynamic equations were done for the model substance Ni with and without additional magnetic field. As a result, an innovative magnetic two-phase stirrer system has been developed which enables the controlled influence on the melt ranging from intensive inwards/outwards flows to flows almost at rest. The selection of parameters necessary for the desired fluid flow is determined from numerical simulation. The basis for the calculations are the process-related fluid flow conditions which are determined by the mode of heating, heat radiation at the free surface and material parameters. This treatment of the problem leads to the customised magnetic field for the special intermetallic compound. The application of the new magnetic system leads to a distinct improvement of the solid-liquid interface validated on experiments with the model substance Nickel.

Hermann, R.; Behr, G.; Gerbeth, G.; Priede, J.; Uhlemann, H.-J.; Fischer, F.; Schultz, L.

2005-02-01

398

Uranium and manganese assembled in a wheel-shaped nanoscale single-molecule magnet with high spin-reversal barrier  

NASA Astrophysics Data System (ADS)

Discrete molecular compounds that exhibit both magnetization hysteresis and slow magnetic relaxation below a characteristic ‘blocking’ temperature are known as single-molecule magnets. These are promising for applications including memory devices and quantum computing, but require higher spin-inversion barriers and hysteresis temperatures than currently achieved. After twenty years of research confined to the d- block transition metals, scientists are moving to the f-block to generate these properties. We have now prepared, by cation-promoted self-assembly, a large 5f-3d U12Mn6 cluster that adopts a wheel topology and exhibits single-molecule magnet behaviour. This uranium-based molecular wheel shows an open magnetic hysteresis loop at low temperature, with a non-zero coercive field (below 4 K) and quantum tunnelling steps (below 2.5 K), which suggests that uranium might indeed provide a route to magnetic storage devices. This molecule also represents an interesting model for actinide nanoparticles occurring in the environment and in spent fuel separation cycles.

Mougel, Victor; Chatelain, Lucile; Pécaut, Jacques; Caciuffo, Roberto; Colineau, Eric; Griveau, Jean-Christophe; Mazzanti, Marinella

2012-12-01

399

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

PubMed

It is demonstrated that the threshold current for damping compensation can be reached in a 5???m diameter YIG(20??nm)|Pt(7??nm) disk. The demonstration rests upon the measurement of the ferromagnetic resonance linewidth as a function of I_{dc} using a magnetic resonance force microscope (MRFM). It is shown that the magnetic losses of spin-wave modes existing in the magnetic insulator can be reduced or enhanced by at least a factor of 5 depending on the polarity and intensity of an in-plane dc current I_{dc} flowing through the adjacent normal metal with strong spin-orbit interaction. Complete compensation of the damping of the fundamental mode by spin-orbit torque is reached for a current density of ?3×10^{11}??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. PMID:25415921

Hamadeh, A; d'Allivy Kelly, O; Hahn, C; Meley, H; Bernard, R; Molpeceres, A H; Naletov, V V; Viret, M; Anane, A; Cros, V; Demokritov, S O; Prieto, J L; Muñoz, M; de Loubens, G; Klein, O

2014-11-01

400

Single spin asymmetries in charged kaon production from semi-inclusive deep inelastic scattering on a transversely polarized 3He target  

We report the first measurement of target single spin asymmetries of charged kaons produced in semi-inclusive deep inelastic scattering of electrons off a transversely polarized 3He target. Both the Collins and Sivers moments, which are related to the nucleon transversity and Sivers distributions, respectively, are extracted over the kinematic range of 0.1

Zhao, Y. X.; Wang, Y.; Allada, K.; Aniol, K.; Annand, J. R.; Averett, T.; Benmokhtar, F.; Bertozzi, W.; Bradshaw, P. C.; Bosted, P.; Camsonne, A.; Canan, M.; Cates, G. D.; Chen, C.; Chen, J.-P.; Chen, W.; Chirapatpimol, K.; Chudakov, E.; Cisbani, E.; Cornejo, J. C.; Cusanno, F.; Dalton, M. M.; Deconinck, W.; de Jager, C. W.; De Leo, R.; Deng, X.; Deur, A.; Ding, H.; Dolph, P. A.; Dutta, C.; Dutta, D.; El Fassi, L.; Frullani, S.; Gao, H.; Garibaldi, F.; Gaskell, D.; Gilad, S.; Gilman, R.; Glamazdin, O.; Golge, S.; Guo, L.; Hamilton, D.; Hansen, O.; Higinbotham, D. W.; Holmstrom, T.; Huang, J.; Huang, M.; Ibrahim, H. F.; Iodice, M.; Jiang, X.; Jin, G.; Jones, M. K.; Katich, J.; Kelleher, A.; Kim, W.; Kolarkar, A.; Korsch, W.; LeRose, J. J.; Li, X.; Li, Y.; Lindgren, R.; Liyanage, N.; Long, E.; Lu, H.-J.; Margaziotis, D. J.; Markowitz, P.; Marrone, S.; McNulty, D.; Meziani, Z.-E.; Michaels, R.; Moffit, B.; Munoz Camacho, C; Nanda, S.; Narayan, A.; Nelyubin, V.; Norum, B.; Oh, Y.; Osipenko, M.; Parno, D.; Peng, J.-C.; Phillips, S. K.; Posik, M.; Puckett, A. J.; Qian, X.; Qiang, Y.; Rakhman, A.; Ransome, R.; Riordan, S.; Saha, A.; Sawatzky, B.; Schulte, E.; Shahinyan, A.; Shabestari, M. H.; Sirca, S; Stepanyan, S.; Subedi, R.; Sulkosky, V.; Tang, L.-G.; Tobias, A.; Urciuoli, G. M.; Vilardi, I.; Wang, K.; Wojtsekhowski, B.; Yan, X.; Yao, H.; Ye, Y.; Ye, Z.; Yuan, L.; Zhan, X.; Zhang, Y.; Zhang, Y.-W.; Zhao, B.; Zheng, X.; Zhu, L.; Zhu, X.; Zong, X.

2014-11-01

401

One-step electro-spinning/netting technique for controllably preparing polyurethane nano-fiber/net.  

PubMed

Electro-spinning/netting (ESN) as a cutting-edge technique evokes much interest because of its ability in the one-step preparation of versatile nano-fiber/net (NFN) membranes. Here, a controllable fabrication of polyurethane (PU) NFN membranes with attractive structures, consisting of common electrospun nanofibers and two-dimensional (2D) soap bubble-like structured nano-nets via an ESN process is reported. The unique nanoscaled NFN architecture can be finely controlled by regulating the solution properties and several ESN process parameters. The versatile PU nano-nets comprising interlinked nanowires with ultrathin diameters (5-40 nm) mean that the NFN structured membranes possess several excellent characteristics, such as an extremely large specific surface area, high porosity and large stacking density, which would be particularly useful for applications in ultrafiltration, special protective clothing, ultrasensitive sensors, catalyst support and so on. PMID:21858891

Hu, Juanping; Wang, Xianfeng; Ding, Bin; Lin, Jinyou; Yu, Jianyong; Sun, Gang

2011-11-01

402

Control and Detection of the Larmor Precession of F = 2 87Rb Bose-Einstein Condensates by Ramsey Interferometry and Spin-Echo  

NASA Astrophysics Data System (ADS)

Radio-frequency pulses are applied to probe and control the Larmor precession of a spin-2 Bose-Einstein condensate subject to a magnetic field gradient. Using the techniques of Ramsey interferometry and Stern-Gerlach absorption imaging, a helical spin pattern was clearly observed as spatial variations in the atomic density distribution. We experimentally show that the spin echo technique reduces the effects of spatially inhomogeneous and temporally fluctuating spin evolution, and improves the repeatability of the interferometry.

Eto, Yujiro; Sekine, Sawako; Hasegawa, Sho; Sadgrove, Mark; Saito, Hiroki; Hirano, Takuya

2013-05-01

403

Adiabatic Charge Control in a Single Donor Atom Transistor  

E-print Network

We charge an individual donor with electrons stored in a quantum dot in its proximity. A Silicon quantum device containing a single Arsenic donor and an electrostatic quantum dot in parallel is realized in a nanometric field effect transistor. The different coupling capacitances of the donor and the quantum dot with the control and the back gates are exploited to generate a relative rigid shift of their energy spectrum as a function of the back gate voltage, causing the crossing of the energy levels. We observe the sequential tunneling through the $D^{2-}$ and the $D^{3-}$ energy levels of the donor hybridized at the oxide interface at 4.2 K. Their respective states form an honeycomb pattern with the quantum dot states. It is therefore possible to control the exchange coupling of an electron of the quantum dot with the electrons bound to the donor, thus realizing a physical qubit for quantum information processing applications.

Enrico Prati; Matteo Belli; Simone Cocco; Guido Petretto; Marco Fanciulli

2010-05-18

404

Measurement of Single and Double Spin Asymmetries in p(e, e' pi(+/-,0))X Semi-Inclusive Deep-Inelastic Scattering  

NASA Astrophysics Data System (ADS)

Measurements in the late 1980s at CERN revealed that quark spins account for a small fraction of the proton's spin. This so-called spin crisis spurred a number of new experiments to identify the proton's silent spin contributors, namely, the spin of the gluons, which hold the quarks together, and the orbital angular momentum of both quarks and gluons. One such experiment was eg1-dvcs at the Thomas Jefferson National Accelerator Facility in Newport News, Va., which ran in 2009 and collected approximately 19 billion electron triggers for hydrogen. I will present new measurements of the single and double-spin asymmetries ALU, AUL and ALL for pi+, pi - and pi0, measured as a function of Bjorken xB, squared momentum transfer Q2, hadron energy fraction z, and hadron transverse momentum Ph ?. These asymmetries, which are convolutions of transverse-momentum-dependent parton distributions and fragmentation functions, correlate with the transverse momentum, and therefore with the orbital motion, of the struck quark.

Jawalkar, Sucheta Shrikant

405

PHYSICAL REVIEW A 89, 013805 (2014) Single-photon router: Coherent control of multichannel scattering for single photons  

E-print Network

PHYSICAL REVIEW A 89, 013805 (2014) Single-photon router: Coherent control of multichannel 2013; published 7 January 2014) We propose a single-photon router using a single atom with an inversion quantum channels formed with 1D CRWs has been proposed as a quantum router [9], where * Corresponding

Nori, Franco

406

Tightly Regulated and Heritable Division Control in Single Bacterial Cells  

PubMed Central

The robust surface adherence property of the aquatic bacterium Caulobacter crescentus permits visualization of single cells in a linear microfluidic culture chamber over an extended number of generations. The division rate of Caulobacter in this continuous-flow culture environment is substantially faster than in other culture apparati and is independent of flow velocity. Analysis of the growth and division of single isogenic cells reveals that the cell cycle control network of this bacterium generates an oscillatory output with a coefficient of variation lower than that of all other bacterial species measured to date. DivJ, a regulator of polar cell development, is necessary for maintaining low variance in interdivision timing, as transposon disruption of divJ significantly increases the coefficient of variation of both interdivision time and the rate of cell elongation. Moreover, interdivision time and cell division arrest are significantly correlated between mother and daughter cells, providing evidence for epigenetic inheritance of cell division behavior in Caulobacter. The single-cell growth/division results reported here suggest that future predictive models of Caulobacter cell cycle regulation should include parameters describing the variance and inheritance properties of this system. PMID:18469083

Siegal-Gaskins, Dan; Crosson, Sean

2008-01-01

407

Electric-field control of spin waves at room temperature in multiferroic BiFeO3.  

PubMed

To face the challenges lying beyond present technologies based on complementary metal-oxide-semiconductors, new paradigms for information processing are required. Magnonics proposes to use spin waves to carry and process information, in analogy with photonics that relies on light waves, with several advantageous features such as potential operation in the terahertz range and excellent coupling to spintronics. Several magnonic analog and digital logic devices have been proposed, and some demonstrated. Just as for spintronics, a key issue for magnonics is the large power required to control/write information (conventionally achieved through magnetic fields applied by strip lines, or by spin transfer from large spin-polarized currents). Here we show that in BiFeO(3), a room-temperature magnetoelectric material, the spin-wave frequency (>600 GHz) can be tuned electrically by over 30%, in a non-volatile way and with virtually no power dissipation. Theoretical calculations indicate that this effect originates from a linear magnetoelectric effect related to spin-orbit coupling induced by the applied electric field. We argue that these properties make BiFeO(3) a promising medium for spin-wave generation, conversion and control in future magnonics architectures. PMID:21076416

Rovillain, P; de Sousa, R; Gallais, Y; Sacuto, A; Méasson, M A; Colson, D; Forget, A; Bibes, M; Barthélémy, A; Cazayous, M

2010-12-01

408

Stray-field imaging of magnetic vortices with a single diamond spin  

NASA Astrophysics Data System (ADS)

Despite decades of advances in magnetic imaging, obtaining direct, quantitative information with nanometre scale spatial resolution remains an outstanding challenge. Recently, a technique has emerged that employs a single nitrogen-vacancy defect in diamond as an atomic-size magnetometer, which promises significant advances. However, the effectiveness of the technique when applied to magnetic nanostructures remains to be demonstrated. Here we use a scanning nitrogen-vacancy magnetometer to image a magnetic vortex, which is one of the most iconic objects of nanomagnetism, owing to the small size (~10?nm) of the vortex core. We report three-dimensional, vectorial and quantitative measurements of the stray magnetic field emitted by a vortex in a ferromagnetic square dot, including the detection of the vortex core. We find excellent agreement with micromagnetic simulations, both for regular vortex structures and for higher-order magnetization states. These experiments establish scanning nitrogen-vacancy magnetometry as a practical and unique tool for fundamental studies in nanomagnetism.

Rondin, L.; Tetienne, J.-P.; Rohart, S.; Thiaville, A.; Hingant, T.; Spinicelli, P.; Roch, J.-F.; Jacques, V.

2013-07-01

409

Controlled permeation of cell membrane by single bubble acoustic cavitation  

PubMed Central

Sonoporation is the membrane disruption generated by ultrasound and has been exploited as a non-viral strategy for drug and gene delivery. Acoustic cavitation of microbubbles has been recognized to play an important role in sonoporation. However, due to the lack of adequate techniques for precise control of cavitation activities and real-time assessment of the resulting sub-micron process of sonoporation, limited knowledge has been available regarding the detail processes and correlation of cavitation with membrane disruption at the single cell level. In the current study, we developed a combined approach including optical, acoustic, and electrophysiological techniques to enable synchronized manipulation, imaging, and measurement of cavitation of single bubbles and the resulting cell membrane disruption in real-time. Using a self-focused femtosecond laser and high frequency (7.44 MHz) pulses, a single microbubble was generated and positioned at a desired distance from the membrane of a Xenopus oocyte. Cavitation of the bubble was achieved by applying a low frequency (1.5 MHz) ultrasound pulse (duration 13.3 or 40 µs) to induce bubble collapse. Disruption of the cell membrane was assessed by the increase in the transmembrane current (TMC) of the cell under voltage clamp. Simultaneous high-speed bright field imaging of cavitation and measurements of the TMC were obtained to correlate the ultrasound-generated bubble activities with the cell membrane poration. The change in membrane permeability was directly associated with the formation of a sub-micrometer pore from a local membrane rupture generated by bubble collapse or bubble compression depending on ultrasound amplitude and duration. The impact of the bubble collapse on membrane permeation decreased rapidly with increasing distance (D) between the bubble (diameter d) and the cell membrane. The effective range of cavitation impact on membrane poration was determined to be D/d = 0.75. The maximum mean radius of the pores was estimated from the measured TMC to be 0.106 ± 0.032 µm (n = 70) for acoustic pressure of 1.5 MPa (duration 13.3 µs), and increased to 0.171 ± 0.030 µm (n = 125) for acoustic pressure of 1.7 MPa and to 0.182 ± 0.052 µm (n=112) for a pulse duration of 40 µs (1.5 MPa). These results from controlled cell membrane permeation by cavitation of single bubbles revealed insights and key factors affecting sonoporation at the single cell level. PMID:21945682

Zhou, Y.; Yang, K.; Cui, J.; Ye, J. Y.; Deng, C. X.

2011-01-01

410

Mammalian monogamy is not controlled by a single gene  

PubMed Central

Complex social behavior in Microtus voles and other mammals has been postulated to be under the direct genetic control of a single locus: the arginine vasopressin 1a receptor (avpr1a) gene. Using a phylogenetic approach, we show that a repetitive element in the promoter region of avpr1a, which reportedly causes social monogamy, is actually widespread in nonmonogamous Microtus and other rodents. There was no evidence for intraspecific polymorphism in regard to the presence or absence of the repetitive element. Among 25 rodent species studied, the element was absent in only two closely related nonmonogamous species, indicating that this absence is certainly the result of an evolutionarily recent loss. Our analyses further demonstrate that the repetitive structures upstream of the avpr1a gene in humans and primates, which have been associated with social bonding, are evolutionarily distinct from those in rodents. Our evolutionary approach reveals that monogamy in rodents is not controlled by a single polymorphism in the promoter region of the avpr1a gene. We thus resolve the contradiction between the claims for an evolutionarily conserved genetic programming of social behavior in mammals and the vast evidence for highly complex and flexible mating systems. PMID:16832060

Fink, Sabine; Excoffier, Laurent; Heckel, Gerald

2006-01-01

411

Single Cell Adhesion Assay Using Computer Controlled Micropipette  

PubMed Central

Cell adhesion is a fundamental phenomenon vital for all multicellular organisms. Recognition of and adhesion to specific macromolecules is a crucial task of leukocytes to initiate the immune response. To gain statistically reliable information of cell adhesion, large numbers of cells should be measured. However, direct measurement of the adhesion force of single cells is still challenging and today’s techniques typically have an extremely low throughput (5–10 cells per day). Here, we introduce a computer controlled micropipette mounted onto a normal inverted microscope for probing single cell interactions with specific macromolecules. We calculated the estimated hydrodynamic lifting force acting on target cells by the numerical simulation of the flow at the micropipette tip. The adhesion force of surface attached cells could be accurately probed by repeating the pick-up process with increasing vacuum applied in the pipette positioned above the cell under investigation. Using the introduced methodology hundreds of cells adhered to specific macromolecules were measured one by one in a relatively short period of time (?30 min). We blocked nonspecific cell adhesion by the protein non-adhesive PLL-g-PEG polymer. We found that human primary monocytes are less adherent to fibrinogen than their in vitro differentiated descendants: macrophages and dendritic cells, the latter producing the highest average adhesion force. Validation of the here introduced method was achieved by the hydrostatic step-pressure micropipette manipulation technique. Additionally the result was reinforced in standard microfluidic shear stress channels. Nevertheless, automated micropipette gave higher sensitivity and less side-effect than the shear stress channel. Using our technique, the probed single cells can be easily picked up and further investigated by other techniques; a definite advantage of the computer controlled micropipette. Our experiments revealed the existence of a sub-population of strongly fibrinogen adherent cells appearing in macrophages and highly represented in dendritic cells, but not observed in monocytes. PMID:25343359

Salanki, Rita; Hos, Csaba; Orgovan, Norbert; Peter, Beatrix; Sandor, Noemi; Bajtay, Zsuzsa; Erdei, Anna; Horvath, Robert; Szabo, Balint

2014-01-01

412

Stray-field imaging of magnetic vortices with a single diamond spin.  

PubMed

Despite decades of advances in magnetic imaging, obtaining direct, quantitative information with nanometre scale spatial resolution remains an outstanding challenge. Recently, a technique has emerged that employs a single nitrogen-vacancy defect in diamond as an atomic-size magnetometer, which promises significant advances. However, the effectiveness of the technique when applied to magnetic nanostructures remains to be demonstrated. Here we use a scanning nitrogen-vacancy magnetometer to image a magnetic vortex, which is one of the most iconic objects of nanomagnetism, owing to the small size (~10?nm) of the vortex core. We report three-dimensional, vectorial and quantitative measurements of the stray magnetic field emitted by a vortex in a ferromagnetic square dot, including the detection of the vortex core. We find excellent agreement with micromagnetic simulations, both for regular vortex structures and for higher-order magnetization states. These experiments establish scanning nitrogen-vacancy magnetometry as a practical and unique tool for fundamental studies in nanomagnetism. PMID:23900221

Rondin, L; Tetienne, J-P; Rohart, S; Thiaville, A; Hingant, T; Spinicelli, P; Roch, J-F; Jacques, V

2013-01-01

413

Single spin asymmetries of inclusive hadrons produced in electron scattering from a transversely polarized 3He target  

NASA Astrophysics Data System (ADS)

We report 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. The experiment was conducted at Jefferson Lab in Hall A using a 5.9-GeV electron beam. Three types of hadrons (?±, K±, and proton) were detected in the transverse hadron momentum range 0.54

Allada, K.; Zhao, Y. X.; Aniol, K.; Annand, J. R. M.; Averett, T.; Benmokhtar, F.; Bertozzi, W.; Bradshaw, P. C.; Bosted, P.; Camsonne, A.; Canan, M.; Cates, G. D.; Chen, C.; Chen, J.-P.; Chen, W.; Chirapatpimol, K.; Chudakov, E.; Cisbani, E.; Cornejo, J. C.; Cusanno, F.; Dalton, M.; Deconinck, W.; de Jager, C. W.; De Leo, R.; Deng, X.; Deur, A.; Ding, H.; Dolph, P. A. M.; Dutta, C.; Dutta, D.; Fassi, L. El; Frullani, S.; Gao, H.; Garibaldi, F.; Gaskell, D.; Gilad, S.; Gilman, R.; Glamazdin, O.; Golge, S.; Guo, L.; Hamilton, D.; Hansen, O.; Higinbotham, D. W.; Holmstrom, T.; Huang, J.; Huang, M.; Ibrahim, H. F.; Iodice, M.; Jiang, X.; Jin, G.; Jones, M. K.; Katich, J.; Kelleher, A.; Kim, W.; Kolarkar, A.; Korsch, W.; LeRose, J. J.; Li, X.; Li, Y.; Lindgren, R.; Liyanage, N.; Long, E.; Lu, H.-J.; Margaziotis, D. J.; Markowitz, P.; Marrone, S.; McNulty, D.; Meziani, Z.-E.; Michaels, R.; Moffit, B.; Camacho, C. Muñoz; Nanda, S.; Narayan, A.; Nelyubin, V.; Norum, B.; Oh, Y.; Osipenko, M.; Parno, D.; Peng, J.-C.; Phillips, S. K.; Posik, M.; Puckett, A. J. R.; Qian, X.; Qiang, Y.; Rakhman, A.; Ransome, R.; Riordan, S.; Saha, A.; Sawatzky, B.; Schulte, E.; Shahinyan, A.; Shabestari, M. H.; Širca, S.; Stepanyan, S.; Subedi, R.; Sulkosky, V.; Tang, L.-G.; Tobias, A.; Urciuoli, G. M.; Vilardi, I.; Wang, K.; Wang, Y.; Wojtsekhowski, B.; Yan, X.; Yao, H.; Ye, Y.; Ye, Z.; Yuan, L.; Zhan, X.; Zhang, Y.; Zhang, Y.-W.; Zhao, B.; Zheng, X.; Zhu, L.; Zhu, X.; Zong, X.; Jefferson Lab Hall A Collaboration

2014-04-01

414

Magnetization process and quantum entanglement in spin-1 XXZ model with single-ion anisotropy under external field  

NASA Astrophysics Data System (ADS)

By the infinite time-evolving block decimation (iTEBD) technique, the magnetization process and the quantum phase transitions (QPTs) in the spin-1 XXZ model with single-ion anisotropy under external field are investigated. It is found that, all the phases will be destroyed by a sufficient strong magnetic field. Before they come into the ferromagnetic (fully polarized) phase, some interesting intermediate phases are induced. A pseudo order Oixy=?{<+<} with finite truncation dimension ? can be used to describe the XY1 phase. Especially, the Oxyi with finite ? is found to be nonzero in the XY1 phase, but vanishes in the XY2 phase. It means that two kinds of XY phases can be distinguished by the pseudo order parameter Oxyi. All the QPTs can be described by the behavior of the entanglement entropy and the ground-state energy. QPTs from the XY phase to the large-D, Haldane, and antiferromagnetic phases are found to be infinite-order BKT type transitions, but the QPTs from the XY1 phase to the ferromagnetic phase and XY2 have second-order characters. In addition, doubly degenerate entanglement spectra are observed in the Haldane phase.

Liu, Guang-Hua; Li, Wei; You, Wen-Long; Su, Gang; Tian, Guang-Shan

2014-06-01

415

Single and double spin asymmetries for pion electro-production from the deuteron in the resonance region  

NASA Astrophysics Data System (ADS)

The single and double spin asymmetries At and Aet have been measured in pi- electro-production off the deuteron using a longitudinally polarized electron beam and a polarized ND3 target. The electron beam was polarized using a strained GaAs cathode and the target was polarized using Dynamic Nuclear Polarization. The data were collected at beam energies of 1.6, 1.7, 2.5 and 4.2 GeV in Hall B at Jefferson Lab in the spring of 2001. The final state particles were detected in the CEBAF Large Acceptance Spectrometer (CLAS). The d(e,e'pi-p)p exclusive channel was identified using the missing mass technique and the asymmetries were extracted as a function of the momentum transfer Q2, invariant mass W, and center of mass pion angles cos(theta*) and ?*. The results are generally in agreement with the phenomenological model MAID at low energies, but there are discrepancies in the 2nd and 3rd resonance regions, as well as at forward angles.

Careccia, Sharon L.

416

A Mononuclear Fe(III) Single Molecule Magnet with a 3/2<->5/2 Spin Crossover  

PubMed Central

The air stable complex [(PNP)FeCl2] (1) (PNP = N[2-P(CHMe2)2-4-methylphenyl]2?), prepared from one-electron oxidation of [(PNP)FeCl] with ClCPh3, displays an unusual S = 3/2 to S = 5/2 transition above 80 K as inferred by the dc SQUID magnetic susceptibility measurement. The ac SQUID magnetization data, at zero field and between frequencies 10 and 1042 Hz, clearly reveals complex 1 to undergo a frequency dependent of the out-of-phase signal and thus be a single molecular magnet with a thermally activated barrier of Ueff = 32-36 cm?1 (47 - 52 K). Variable temperature Mössbauer data also corroborate a significant temperature dependence in ? and ?EQ values for 1, which is in agreement with the system undergoing a change in spin state. Likewise, variable temperature X-band EPR spectra of 1 reveals the S = 3/2 to be likely the ground state with the S = 5/2 being close in energy. Multi-edge XAS absorption spectra suggest the electronic structure of 1 to be highly covalent with an effective iron oxidation state that is more reduced than the typical ferric complexes due to the significant interaction of the phosphine groups in PNP and Cl ligands with iron. A variable temperature single crystal X-ray diffraction study of 1 collected between 30-300 K also reveals elongation of the Fe–P bond lengths and increment in the Cl–Fe–Cl angle as the S = 5/2 state is populated. Theoretical studies show overall similar orbital pictures except for the d(z2) orbital which is the most sensitivity to change in the geometry and bonding where the quartet (4B) and the sextet (6A) states are close in energy. PMID:22817325

Tran, Ba L.; Adhikari, Debashis; Pink, Maren; Heinemann, Frank W.; Sutter, Jorg; Szilagyi, Robert K.

2012-01-01

417

Electric field controlled reversible magnetic anisotropy switching studied by spin rectification  

NASA Astrophysics Data System (ADS)

In this letter, spin rectification was used to study the electric field controlled dynamic magnetic properties of the multiferroic composite which is a Co stripe with induced in-plane anisotropy deposited onto a Pb(Mg1/3Nb2/3)O3-PbTiO3 substrate. Due to the coupling between piezoelectric and magnetoelastic effects, a reversible in-plane anisotropy switching has been realized by varying the history of the applied electric field. This merit results from the electric hysteresis of the polarization in the nonlinear piezoelectric regime, which has been proved by a butterfly type electric field dependence of the in-plane anisotropy field. Moreover, the electric field dependent effective demagnetization field and linewidth have been observed at the same time.

Zhou, Hengan; Fan, Xiaolong; Wang, Fenglong; Jiang, Changjun; Rao, Jinwei; Zhao, Xiaobing; Gui, Y. S.; Hu, C.-M.; Xue, Desheng

2014-03-01