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1

Electrical control of single spin dynamics  

NASA Astrophysics Data System (ADS)

Over ten years ago, Daniel Loss and David DiVincenzo proposed using the spin of a single electron as a quantum bit. At the time of the proposal, it was not possible to trap a single electron in a device and measure its spin, let alone demonstrate control of quantum coherence. In this talk I will describe recent progress in the field, focusing on two new methods for single spin control that have been developed by my group at Princeton. The first method is based on quantum interference and implements spin-interferometry on a chip. The second method utilizes the strong spin-orbit coupling of InAs. By shifting the orbital position of the electronic wavefunction at gigahertz frequencies, we can control the orientation of a single electron spin and measure the full g-tensor, which exhibits a large anisotropy due to spin-orbit interactions. Both methods for single spin control are orders of magnitude faster than conventional electron spin resonance and allow investigations of single spin coherence in the presence of fluctuating nuclear and spin-orbit fields. I will also describe recent efforts to transfer these methods to silicon quantum dots, where the effects of fluctuating nuclear fields are much smaller.

Petta, Jason

2012-02-01

2

Coherent, mechanical control of a single electronic spin.  

PubMed

We demonstrate 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 in diamond. Synchronization of spin-addressing protocols to the motion of the driven oscillator is used to fully exploit the coherence of this hybrid mechanical-spin system. We demonstrate applications of this coherent mechanical spin-control technique to nanoscale scanning magnetometry. PMID:22800099

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

2012-08-01

3

Quantum Control over Single Spins in Diamond  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

4

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

5

High precision quantum control of single donor spins in silicon.  

PubMed

The Stark shift of the hyperfine coupling constant is investigated for a P donor in Si far below the ionization regime in the presence of interfaces using tight-binding and band minima basis approaches and compared to the recent precision measurements. In contrast with previous effective mass-based results, the quadratic Stark coefficient obtained from both theories agrees closely with the experiments. It is also shown that there is a significant linear Stark effect for an impurity near the interface, whereas, far from the interface, the quadratic Stark effect dominates. This work represents the most sensitive and precise comparison between theory and experiment for single donor spin control. Such precise control of single donor spin states is required particularly in quantum computing applications of single donor electronics, which forms the driving motivation of this work. PMID:17678301

Rahman, Rajib; Wellard, Cameron J; Bradbury, Forrest R; Prada, Marta; Cole, Jared H; Klimeck, Gerhard; Hollenberg, Lloyd C L

2007-07-20

6

Controlling Single-Particle Coherence and Spin Squeezing with Stimulated Raman Transition  

NASA Astrophysics Data System (ADS)

We present a scheme for controlling single-particle coherence and spin squeezing of atom-photon with stimulated Raman transition. Here we are focus on the dependence of spin squeezing parameter on the mean photon number. We first derive the effective Hamiltonian and then obtain the analytical solution for state vector, the single-particle coherence and spin squeezing parameter. The stronger spin squeezing can be created by adding the mean photon number.

Yi, Xiao-Jie; Huang, Guo-Qiang; Wang, Jian-Min

2013-10-01

7

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

NASA Astrophysics Data System (ADS)

The electron spin of a donor in silicon is an excellent candidate for a solid-state qubit. It is known to have very long coherence and relaxation times in bulk [1], and several architectures have been proposed to integrate donor spin qubits with classical silicon microelectronics [2]. Here we show the first experimental proof of single-shot readout of an electron spin in silicon. The device consists of implanted phosphorus donors, tunnel-coupled to a silicon Single-Electron Transistor (SET), where the SET island is used as a reservoir for spin-to-charge conversion [3]. The large charge transfer signals allow readout fidelity >90% with 3 ?s response time. By measuring the occurrence of excited spin states as a function of wait time, we find spin lifetimes (T1) up to ˜ 6 s at B = 1.5 T, and a magnetic-field dependence T1-1 B^5 consistent with that of phosphorus donors in silicon [4]. In a subsequent experiment we have integrated the single-shot spin readout device with an on-chip microwave transmission line for coherent control of the electron spin. We have detected the spin resonance of a single electron, and observed two hyperfine-split resonance lines, consistent with Stark-shifted coupling to the ^31P nuclear spin. Further experiments are underway to demonstrate coherent spin control and observe Rabi oscillations. This demonstrates the microwave control of a single spin, combined -- for the first time in the same experiment -- with electrically detected single-shot spin readout. [1] A. M. Tyryshkin et al., Phys. Rev. B 68, 193207 (2003). [2] L. C. L. Hollenberg et al., Phys. Rev. B. 74, 045311 (2006). [3] A. Morello et al., Phys. Rev. B 80, 081307(R) (2009). [4] A. Morello et al., Nature 467, 687 (2010).

Morello, Andrea

2011-03-01

8

Fast control of nuclear spin polarization in an optically pumped single quantum dot  

NASA Astrophysics Data System (ADS)

Highly polarized nuclear spins within a semiconductor quantum dot induce effective magnetic (Overhauser) fields of up to several Tesla acting on the electron spin, or up to a few hundred mT for the hole spin. Recently this has been recognized as a resource for intrinsic control of quantum-dot-based spin quantum bits. However, only static long-lived Overhauser fields could be used. Here we demonstrate fast redirection on the microsecond timescale of Overhauser fields on the order of 0.5 T experienced by a single electron spin in an optically pumped GaAs quantum dot. This has been achieved using coherent control of an ensemble of 105 optically polarized nuclear spins by sequences of short radiofrequency pulses. These results open the way to a new class of experiments using radiofrequency techniques to achieve highly correlated nuclear spins in quantum dots, such as adiabatic demagnetization in the rotating frame leading to sub-?K nuclear spin temperatures, rapid adiabatic passage, and spin squeezing.

Makhonin, M. N.; Kavokin, K. V.; Senellart, P.; Lemaître, A.; Ramsay, A. J.; Skolnick, M. S.; Tartakovskii, A. I.

2011-11-01

9

Excited-State Spectroscopy and Control of Single Spins in Diamond  

NASA Astrophysics Data System (ADS)

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

Fuchs, G. D.

2009-03-01

10

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

11

Method for Full Bloch-Sphere Control of a Localized Spin in a Quantum Dot via a Single Electrical Gate  

NASA Astrophysics Data System (ADS)

Manipulating individual spins in solids requires quickly and coherently reorienting localized spins while leaving neighboring spins unaffected. Difficulties confining oscillating magnetic fields have motivated alternate approaches that use electric fields to change the local magnetic environment, including moving an electron within a hyperfine field gradient or fringe-field gradient. Higher temperatures require spins to be localized in much smaller quantum dots, where these techniques are less effective. In contrast, g-tensor manipulation techniques[1] couple an electric field to the spin via the spin-orbit interaction, and should be scalable to small dots with large confinement. Here we calculate the g-tensor of a single electron in a small quantum dot and show the symmetry of its electric field dependence permits full Bloch sphere control of the spin using an electric field applied in a single direction. We find the spin manipulation frequency of an InAs/GaAs QD in 1 Tesla exceeds 150 MHz. We acknowledge support of an ONR MURI and an NSF NIRT. [1] Kato et al. Nature 299, 1201 (2003)

Pingenot, Joseph; Pryor, Craig E.; Flatté, Michael E.

2008-03-01

12

All-electrical control of quantum gates for single heavy-hole spin qubits  

NASA Astrophysics Data System (ADS)

In this paper several nanodevices which realize basic single heavy-hole qubit operations are proposed and supported by time-dependent self-consistent Poisson-Schrödinger calculations using a four band heavy-hole-light-hole model. In particular we propose a set of nanodevices which can act as Pauli X, Y, Z quantum gates and as a gate that acts similar to a Hadamard gate (i.e., it creates a balanced superposition of basis states but with an additional phase factor) on the heavy-hole spin qubit. We also present the design and simulation of a gated semiconductor nanodevice which can realize an arbitrary sequence of all these proposed single quantum logic gates. The proposed devices exploit the self-focusing effect of the hole wave function which allows for guiding the hole along a given path in the form of a stable solitonlike wave packet. Thanks to the presence of the Dresselhaus spin-orbit coupling, the motion of the hole along a certain direction is equivalent to the application of an effective magnetic field which induces in turn a coherent rotation of the heavy-hole spin. The hole motion and consequently the quantum logic operation is initialized only by weak static voltages applied to the electrodes which cover the nanodevice. The proposed gates allow for an all electric and ultrafast (tens of picoseconds) heavy-hole spin manipulation and give the possibility to implement a scalable architecture of heavy-hole spin qubits for quantum computation applications.

Szumniak, P.; Bednarek, S.; Paw?owski, J.; Partoens, B.

2013-05-01

13

Single spin asymmetries at CLAS  

SciTech Connect

We present recent results from Jefferson Lab's CLAS detector on beam and target single-spin asymmetries in single pion electroproduction off unpolarized hydrogen and polarized NH 3 targets. Non-zero single-beam and single-target spin asymmetries are observed for the first time in semi-inclusive and exclusive pion production in hard-scattering kinematics.

Harut Avakian; Latifa Elouadrhiri

2003-05-19

14

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

15

Time resolved control of electron tunnelling times and single-shot spin readout in a quantum dot  

NASA Astrophysics Data System (ADS)

We are pursuing a capability to perform time resolved manipulations of single spins in quantum dot circuits involving more than two quantum dots. In this paper, we demonstrate full counting statistics as well as averaging techniques used to calibrate the tunnel barriers. We make use of this to implement the Delft protocol [1] for single shot single spin readout in a device designed to form a triple quantum dot potential. We are able to tune the tunnelling times over around three orders of magnitude. We obtain a spin relaxation time of 300 ?s at 10 T.

Gaudreau, L.; Kam, A.; Kycia, J. B.; Studenikin, S. A.; Granger, G.; Mason, J. D.; Zawadzki, P.; Sachrajda, A. S.

2010-02-01

16

Single-donor spin qubits in silicon  

NASA Astrophysics Data System (ADS)

The idea of using the spin of a single donor atom in silicon to encode quantum information goes back to the Kane proposal [1] in 1998. We have now resolved the technical challenges involved in the readout and control of the electron and nuclear spin of a single atom. The key breakthrough was the development of a device structure where the donor is tunnel-coupled to the island of an electrostatically-induced single-electron transistor [2]. This device allowed the single-shot readout of the electron spin with visibility > 90% and 3 ?s readout time [3]. More recently we have integrated the single-shot readout device with a broadband microwave transmission line to coherently control the electron and nuclear spins. The resonance frequency of the electron is found by monitoring the excess spin-up counts while sweeping the microwave frequency. At any time, one of two possible frequencies is found to be in resonance with the electron spin, depending on the state of the nuclear spin. Alternately probing the two frequencies yields the (quantum nondemolition) single-shot readout of the nucleus, with fidelity > 99.99%. Then we demonstrate the coherent control (Rabi oscillations) of both the electron and the nucleus, both detected in single-shot mode. The ?-pulse fidelity is ˜70% for the electron and ˜99% for the nucleus. Hahn echo and multi-pulse dynamical decoupling sequences allow us to explore the true coherence of the qubits, yielding T2e˜200 ?s for the electron, and T2n˜60 ms for the nucleus. These results are fully consistent with the bulk values for donors in a natural Si sample. Further improvements in qubit coherence can be expected by moving to isotopically pure ^28Si substrates.[4pt] [1] B. E. Kane, Nature 393, 133 (1998).[0pt] [2] A. Morello et al., Phys. Rev. B 80, 081307(R) (2009).[0pt] [3] A. Morello et al., Nature 467, 687 (2010).

Morello, Andrea

2012-02-01

17

Gate controlled spin pumping at a quantum spin Hall edge  

NASA Astrophysics Data System (ADS)

We propose a four-terminal device designed to manipulate by all electrical means the spin of a magnetic adatom positioned at the edge of a quantum spin Hall insulator. We show that an electrical gate, able to tune the interface resistance between a quantum spin Hall insulator and the source and drain electrodes, can switch the device between two regimes: one where the system exhibits spin pumping and the other where the adatom remains in its ground state. This demonstrates an all-electrical route to control single spins by exploiting helical edge states of topological materials.

Narayan, Awadhesh; Hurley, Aaron; Sanvito, Stefano

2013-09-01

18

Single-pulse terahertz coherent control of spin resonance in the canted antiferromagnet YFeO3, mediated by dielectric anisotropy  

NASA Astrophysics Data System (ADS)

We report on the coherent control of terahertz (THz) spin waves in a canted antiferromagnet yttrium orthoferrite, YFeO3, associated with a quasiferromagnetic (quasi-FM) spin resonance at a frequency of 0.3 THz, using a single-incident THz pulse. The spin resonance is excited impulsively by the magnetic field component of the THz pulse. The intrinsic dielectric anisotropy of YFeO3 in the THz range allows for coherent control of both the amplitude and the phase of the excited spin wave. The coherent control is based on simultaneous generation of two interfering phase-shifted spin waves whose amplitudes and relative phase, dictated by the dielectric anisotropy of the YFeO3 crystal, can be controlled by varying the polarization of the incident THz pulse with respect to the crystal axes. The spatially anisotropic decay of the THz-excited FM spin resonance in YFeO3, leading to an increasingly linear polarization of the THz oscillation at the spin resonance frequency, suggests a key role of magnon-phonon coupling in spin-wave energy dissipation.

Jin, Zuanming; Mics, Zoltán; Ma, Guohong; Cheng, Zhenxiang; Bonn, Mischa; Turchinovich, Dmitry

2013-03-01

19

Polarization and readout of coupled single spins in diamond.  

PubMed

We study the coupling of a single nitrogen-vacancy center in diamond to a nearby single nitrogen defect at room temperature. The magnetic dipolar coupling leads to a splitting in the electron spin resonance frequency of the nitrogen-vacancy center, allowing readout of the state of a single nitrogen electron spin. At magnetic fields where the spin splitting of the two centers is the same, we observe a strong polarization of the nitrogen electron spin. The amount of polarization can be controlled by the optical excitation power. We combine the polarization and the readout in time-resolved pump-probe measurements to determine the spin relaxation time of a single nitrogen electron spin. Finally, we discuss indications for hyperfine-induced polarization of the nitrogen nuclear spin. PMID:17026336

Hanson, R; Mendoza, F M; Epstein, R J; Awschalom, D D

2006-08-25

20

Nanoscale imaging magnetometry with single spins in diamond  

NASA Astrophysics Data System (ADS)

Single Nitrogen-Vacancy colour centers in diamond are gaining popularity because of its exceptional optical and spin properties. The single spin of the defect can be manipulated optically, providing a efficient way to entangle single electron spins and couple nuclear spins qubits in diamond.[1] Long spin coherence time of these single defects finds application as sensitive magnetic field probes. Using engineered diamond we can achieve ultrahigh sensitivity using which we will be able to detect a single external electron or nucelar spin.[2] Controlled creation of these color centers inside nanodiamonds offers diverse applications. By attaching these single spins to the tip of a scanning probe, we were able to perform sensitive scanning probe magnetometry at nanoscale.[3] Improving this device by using quantum grade diamond and synchronized NMR pulse sequences we would have the ability to perform nanoscale NMR/MRI of single molecules.[0pt] [1] Neumann, P. et al. Multipartite Entanglement Among Single Spins in Diamond. Science 320, 1326-1329 (2008).[0pt] [2] Maze, J. R. et al. Nanoscale magnetic sensing with an individual electronic spin in diamond. Nature 455, 644-647(2008).[0pt] [3] Balasubramanian, G. et al. Nanoscale imaging magnetometry with diamond spins under ambient conditions. Nature 455, 648-651(2008).

Balasubramanian, Gopalakrishnan; Tisler, Julia; Kolesov, Roman; Jelezko, Fedor; Wrachtrup, Joerg

2009-03-01

21

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

22

Coherent control of spin currents*  

NASA Astrophysics Data System (ADS)

The use of above-band-gap excitation in semiconductors explores a range of nonlinear processes qualitatively different than the below-band-gap effects more familiar in nonlinear optics. Quantum interference between different electron-hole excitation processes allows for the optical injection of currents and spin currents in semiconductors on ultrafast time scales. Currents characterized by average velocities on the order of a thousand kilometres per second, for example, can be created on the time scale of a few femtoseconds, with electrons acquiring their energy from the photons and their momentum from the underlying lattice. Some of these effects are analogous to the kind of directed ionization of electrons, via coherent control, that is possible from atoms, while some hark back to even earlier work on the circular photogalvanic effect that can now be understood from a new perspective. Pure spin currents can also be injected, with electrons of one spin being sent primarily in one direction, and electrons with the opposite spin in the other. We overview our theoretical work on both two-beam and one-beam implementations of these effects, the latter requiring only a single laser frequency. *Work performed in collaboration with R.D.R. Bhat, Ali Najmaie, F. Nastos, N. Laman, and H.M. van Driel (Unitersity of Toronto) and A. Smirl and M. Stevens (University of Iowa) and funded by NSERC, Photonics Research Ontario, and the DARPA Spintronics Program.

Sipe, J. E.

2004-03-01

23

Single-Shot Readout of a Single Nuclear Spin  

NASA Astrophysics Data System (ADS)

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.

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

2010-07-01

24

Repetitive readout of a single electronic spin via quantum logic with nuclear spin ancillae.  

PubMed

Robust measurement of single quantum bits plays a key role in the realization of quantum computation and communication as well as in quantum metrology and sensing. We have implemented a method for the improved readout of single electronic spin qubits in solid-state systems. The method makes use of quantum logic operations on a system consisting of a single electronic spin and several proximal nuclear spin ancillae in order to repetitively readout the state of the electronic spin. Using coherent manipulation of a single nitrogen vacancy center in room-temperature diamond, full quantum control of an electronic-nuclear system consisting of up to three spins was achieved. We took advantage of a single nuclear-spin memory in order to obtain a 10-fold enhancement in the signal amplitude of the electronic spin readout. We also present a two-level, concatenated procedure to improve the readout by use of a pair of nuclear spin ancillae, an important step toward the realization of robust quantum information processors using electronic- and nuclear-spin qubits. Our technique can be used to improve the sensitivity and speed of spin-based nanoscale diamond magnetometers. PMID:19745117

Jiang, L; Hodges, J S; Maze, J R; Maurer, P; Taylor, J M; Cory, D G; Hemmer, P R; Walsworth, R L; Yacoby, A; Zibrov, A S; Lukin, M D

2009-10-01

25

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

SciTech Connect

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

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

2012-09-28

26

A single-spin-current thermal generator  

NASA Astrophysics Data System (ADS)

We theoretically propose a single-spin-current thermal generator consisting of a Rashba quantum dot (QD), one hot electrode and two cold electrodes. The Rashba QD is directly coupled to the three electrodes, and there exists a bridge channel between the two cold electrodes. Our results show the QD device can be used to generate pure spin-up or spin-down currents in cold electrodes in the absence of bias voltages and magnetic materials. The underlying reason is a cooperative effect of the spin-dependent quantum interference effects originating from Rashba spin-orbit interaction in the QD and temperature gradients among the three electrodes. The working conditions for the single-spin-current thermal generator are also clearly presented. Moreover, we also find that the device can be converted from n-type to p-type or vice versa by a gate voltage.

Liu, Y. S.; Yang, X. F.; Hong, X. K.; Chi, F.

2012-07-01

27

Controlling hole spins in quantum dots and wells  

NASA Astrophysics Data System (ADS)

We review recent theoretical results for hole spins influenced by spin-orbit coupling and Coulomb interaction in two-dimensional quantum wells as well as the decoherence of single hole spins in quantum dots due to hyperfine interaction with surrounding nuclear spins. After reviewing the different forms of spin-orbit coupling that are relevant for electrons and heavy holes in III-V semiconductor quantum wells, we illustrate the combined effect of spin-orbit coupling and Coulomb interactions for hole systems on spin-dependent quasiparticle group velocities. We further analyze spin-echo decay for a single hole spin in a nuclear-spin bath, demonstrating that this decoherence source can be controlled in these systems by entering a motional-averaging regime. Throughout this review, we emphasize physical effects that are unique to hole spins (rather than electrons) in nanoscale systems.

Chesi, Stefano; Wang, Xiaoya Judy; Coish, W. A.

2014-05-01

28

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

29

Tunneling spin injection into single layer graphene.  

PubMed

We achieve tunneling spin injection from Co into single layer graphene (SLG) using TiO? seeded MgO barriers. A nonlocal magnetoresistance (?R(NL)) of 130??? is observed at room temperature, which is the largest value observed in any material. Investigating ?R(NL) vs SLG conductivity from the transparent to the tunneling contact regimes demonstrates the contrasting behaviors predicted by the drift-diffusion theory of spin transport. Furthermore, tunnel barriers reduce the contact-induced spin relaxation and are therefore important for future investigations of spin relaxation in graphene. PMID:21231003

Han, Wei; Pi, K; McCreary, K M; Li, Yan; Wong, Jared J I; Swartz, A G; Kawakami, R K

2010-10-15

30

Controlling Spin Coherence with Semiconductor Nanostructures  

NASA Astrophysics Data System (ADS)

We present two emerging opportunities for manipulating and communicating coherent spin states in semiconductors. First, we show that semiconductor microcavities offer unique means of controlling light-matter interactions in confined geometries, resulting in a wide range of applications in optical communications and inspiring proposals for quantum information processing and computational schemes. Studies of spin dynamics in microcavities — a new and promising research field — have revealed novel effects such as polarization beats, stimulated spin scattering, and giant Faraday rotation. Here, we study the electron spin dynamics in optically-pumped GaAs microdisk lasers with quantum wells and interface-fluctuation quantum dots in the active region. In particular, we examine how the electron spin dynamics are modified by the stimulated emission in the disks, and observe an enhancement of the spin coherence time when the optical excitation is in resonance with a high quality (Q ~ 5000) lasing mode.1 This resonant enhancement, contrary to expectations from the observed trend in the carrier recombination time, is then manipulated by altering the cavity design and dimensions. In analogy to devices based on excitonic coherence, this ability to engineer coherent interactions between electron spins and photons may provide novel pathways towards spin dependent quantum optoelectronics. In a second example, the nitrogen-vacancy (N-V) center in diamond has garnered interest as a room-temperature solid-state system not only for exploring electronic and nuclear spin phenomena but also as a candidate for spin-based quantum information processing. Spin coherence times of up to 50 microseconds have been reported for ensembles of N-V centers and a two-qubit gate utilizing the electron spin of a N-V center and the nuclear spin of a nearby C-13 atom has been demonstrated. Here, we present experiments using angle-resolved magneto-photoluminescence microscopy to investigate anisotropic spin interactions of single N-V centers in diamond at room temperature.2 Negative peaks in the photoluminescence intensity are observed as a function of both magnetic field magnitude and angle, and can be explained by coherent spin precession and anisotropic relaxation at spin-level anticrossings. Additionally, precise field alignment with the symmetry axis of a single N-V center reveals the resonant magnetic dipolar coupling of a single "bright" electron spin of an N-V center to small numbers of "dark" spins of nitrogen defects in its immediate vicinity, which are otherwise undetected by photoluminescence. Most recently, we are exploring the possibility of utilizing this magnetic dipole coupling between bright and dark spins to couple two spatially separated single N-V center spins by means of intermediate nitrogen spins. Note from Publisher: This article contains the abstract only.

Awschalom, David D.

31

Single spin asymmetries in electroproduction at CLAS  

SciTech Connect

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

Harut Avakian; Latifa Elouadrhiri

2004-06-02

32

Voltage-controlled spin precession  

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

33

Single-nuclear-spin cavity QED  

SciTech Connect

We constructed a cavity QED system with a diamagnetic atom of {sup 171}Yb and performed projective measurements on a single nuclear spin. Since Yb has no electronic spin and has 1/2 nuclear spin, the procedure of spin polarization and state verification can be dramatically simplified compared with the pseudo-spin-1/2 system. By enhancing the photon emission rate of the {sup 1}S{sub 0}-{sup 3}P{sub 1} transition, projective measurement is implemented for an atom with the measurement time of T{sub meas}=30 {mu}s. Unwanted spin flip and dark counts of the detector lead to systematic error when the present technique is applied for the determination of diagonal elements of an unknown spin state, which is {delta}|{beta}|{sup 2{<=}}2x10{sup -2}. Fast measurement on a long-lived qubit is key to the realization of large-scale one-way quantum computing.

Takeuchi, Makoto; Takei, Nobuyuki; Zhang Peng [ERATO Macroscopic Quantum Control Project, JST, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Doi, Kodai; Kozuma, Mikio [ERATO Macroscopic Quantum Control Project, JST, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Physics, Tokyo Institute of Technology, 2-12-1 O-Okayama, Meguro-ku, Tokyo 152-8550 (Japan); Ueda, Masahito [ERATO Macroscopic Quantum Control Project, JST, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2010-06-15

34

Spin-transfer torque on a single magnetic adatom  

NASA Astrophysics Data System (ADS)

We theoretically show how the spin orientation of a single magnetic adatom can be controlled by spin polarized electrons in a scanning tunnelling microscope configuration. The underlying physical mechanism is spin assisted inelastic tunnelling. Experiments with Mn adatoms deposited on a Cu2N surface have been reported for non-polarized currents [1-2]. We show that by changing the direction of the applied current, the orientation of the magnetic adatom can be completely reversed on a time scale that ranges from a few nanoseconds to microseconds, depending on bias and temperature. The changes in the adatom magnetization direction are, in turn, reflected in the tunnelling conductance. Therefore, this effect opens the possibility of writing/reading a single spin without the need of a local magnetic field.[4pt] [1] C.F. Hirjibehedin, C. P. Lutz, A. J. Heinrich, Science 312, 1021 (2006).[0pt] [2] C. Hirjibehedin et al., Science 317, 1199 (2007).

Delgado, Fernando; José Palacios, Juan; Fernández-Rossier, Joaquín

2010-03-01

35

A single-atom electron spin qubit in silicon.  

PubMed

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

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

2012-09-27

36

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

PubMed

Quantum control of individual spins in condensed-matter devices is an emerging field with a wide range of applications, from nanospintronics to quantum computing. The electron, possessing spin and orbital degrees of freedom, is conventionally used as the carrier of quantum information in proposed devices. However, electrons couple strongly to the environment, and so have very short relaxation and coherence times. It is therefore extremely difficult to achieve quantum coherence and stable entanglement of electron spins. Alternative concepts propose nuclear spins as the building blocks for quantum computing, because such spins are extremely well isolated from the environment and less prone to decoherence. However, weak coupling comes at a price: it remains challenging to address and manipulate individual nuclear spins. Here we show that the nuclear spin of an individual metal atom embedded in a single-molecule magnet can be read out electronically. The observed long lifetimes (tens of seconds) and relaxation characteristics of nuclear spin at the single-atom scale open the way to a completely new world of devices in which quantum logic may be implemented. PMID:22895342

Vincent, Romain; Klyatskaya, Svetlana; Ruben, Mario; Wernsdorfer, Wolfgang; Balestro, Franck

2012-08-16

37

Faraday rotation with a single-nuclear-spin qubit in a high-finesse optical cavity  

SciTech Connect

When an off-resonant light field is coupled with atomic spins, its polarization can rotate depending on the direction of the spins via Faraday rotation, which has been used for monitoring and controlling the atomic spins. We observed Faraday rotation by an angle of more than 10 deg for a single nuclear spin of 1/2 of a {sup 171}Yb atom in a high-finesse optical cavity. By employing the coupling between the single nuclear spin and a photon, we have also demonstrated that the spin can be projected or weakly measured through the projection of the transmitted single ancillary photon.

Takei, Nobuyuki; Takeuchi, Makoto; Zhang, Peng [ERATO Macroscopic Quantum Control Project, Japan Science and Technology Agency, 2-11-16 Yayoi, Bunkyo-Ku, Tokyo 113-8656 (Japan); Eto, Yujiro; Noguchi, Atsushi; Kozuma, Mikio [ERATO Macroscopic Quantum Control Project, Japan Science and Technology Agency, 2-11-16 Yayoi, Bunkyo-Ku, Tokyo 113-8656 (Japan); Department of Physics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8550 (Japan); Ueda, Masahito [ERATO Macroscopic Quantum Control Project, Japan Science and Technology Agency, 2-11-16 Yayoi, Bunkyo-Ku, Tokyo 113-8656 (Japan); Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2010-04-15

38

Gigahertz dynamics of a strongly driven single quantum spin.  

PubMed

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

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

2009-12-11

39

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

40

Electronic readout of a single nuclear spin using a molecular spin transistor  

NASA Astrophysics Data System (ADS)

Quantum control of individual spins in condensed matter devices is an emerging field with a wide range of applications ranging from nanospintronics to quantum computing [1,2]. The electron, with its spin and orbital degrees of freedom, is conventionally used as carrier of the quantum information in the devices proposed so far. However, electrons exhibit a strong coupling to the environment leading to reduced relaxation and coherence times. Indeed quantum coherence and stable entanglement of electron spins are extremely difficult to achieve. We propose a new approach using the nuclear spin of an individual metal atom embedded in a single-molecule magnet (SMM). In order to perform the readout of the nuclear spin, the quantum tunneling of the magnetization (QTM) of the magnetic moment of the SMM in a transitor-like set-up is electronically detected. Long spin lifetimes of an individual nuclear spin were observed and the relaxation characteristics were studied. The manipulation of the nuclear spin state of individual atoms embedded in magnetic molecules opens a completely new world, where quantum logic may be integrated.[4pt] [1] L. Bogani, W. Wernsdorfer, Nature Mat. 7, 179 (2008).[0pt] [2] M. Urdampilleta, S. Klyatskaya, J.P. Cleuziou, M. Ruben, W. Wernsdorfer, Nature Mat. 10, 502 (2011).

Vincent, R.; Klyastskaya, S.; Ruben, M.; Wernsdorfer, W.; Balestro, F.

2012-02-01

41

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

42

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

NASA Technical Reports Server (NTRS)

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

Bainum, P. M.; Sellappan, R.

1977-01-01

43

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

44

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

45

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

46

Optically controlled spins in semiconductor quantum dots  

Microsoft Academic Search

Spins in charged semiconductor quantum dots are currently generating much interest, both from a fundamental physics standpoint, as well as for their potential technological relevance. Being naturally a two-level quantum system, each of these spins can encode a bit of quantum information. Optically controlled spins in quantum dots possess several desirable properties: their spin coherence times are long, they allow

Sophia Economou

2010-01-01

47

Three-dimensional optical manipulation of a single electron spin.  

PubMed

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

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

2013-03-01

48

Three-dimensional optical manipulation of a single electron spin  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

49

Increasing the electron spin coherence time by coherent optical control of the nuclear spin fluctuations  

NASA Astrophysics Data System (ADS)

A single electron spin plays a central role for spin-based quantum information science and electronic devices. One crucial requirement for the future success is to have a long quantum coherence time. It has been demonstrated that in III-V materials, the electron spin coherence time deteriorates rapidly due to the hyperfine coupling with the nuclear environment. Here, we report the increase of the electron spin coherence time by optical controlled suppression of nuclear spin fluctuations through coherent dark-state spectroscopy. The experiment is performed in a single negatively charged InAs self assembled quantum dot (SAQD). The dynamic nuclear spin polarization manifests itself as a hysteresis in the probe absorption spectrum and in the spectral position of the dark state as a function of the frequency scanning direction of the probe field. We demonstrated that the nuclear field can be locked to the maximum trion excitation by observing a flat-top of the trion absorption lineshape, and the switching of the nuclei from unstable to stable configurations by fixing the laser frequencies and monitoring the coherent optical response as a function of time. The optically controlled locking of the nuclear field leads to an enhancement of the electron spin coherence time, which is measured through dark state spectroscopy. The suppression of the nuclear field fluctuations result from a hole spin assisted dynamic nuclear spin polarization feed-back process. We further demonstrated the electron spin coherence enhancement by a three-beam measurement, where two-pump beams lock the nuclear field and the third probe measures the coherence time through the dark state. The inferred spin coherence time is increased by nearly 3 orders of magnitude compared to its thermal value. Our work lays the groundwork for the reproducible preparation of the nuclear spin environment for repetitive control and measurement of a single spin with minimal statistical broadening.

Xu, Xiaodong

2010-03-01

50

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

51

Ultrafast optical control of individual quantum dot spin qubits  

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

52

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

53

Transverse single spin asymmetry measurements at STAR  

NASA Astrophysics Data System (ADS)

Transverse single spin asymmetries A N are expected to be sensitive to par-ton polarization and orbital angular momentum contributions to the nucleon spin. Significantly large A N has been observed in different collision systems such as semi-inclusive deep inelastic scattering (SIDIS) and polarized proton-proton ( pp) collisions, indicating a dominant contribution of partonic interactions in the non-perturbative regime. Therefore it's critical to measure A N in various channels of polarized pp collisions in order to complement SIDIS data and to constrain theoretical models. We report STAR asymmetry measurements on mid-rapidity hadron-jet and di-hadron correlations at ? s = 200 GeV and forward rapidity inclusive hadron production at ? s = 500 GeV polarized pp collisions.

Pan, Yuxi

2014-01-01

54

Electrical detection of spin precession in single layer graphene spin valves with transparent contacts  

Microsoft Academic Search

Spin accumulation and spin precession in single layer graphene are studied by nonlocal spin valve measurements at room temperature. The dependence of the nonlocal magnetoresistance on electrode spacing is investigated and the results indicate a spin diffusion length of ~1.6 mum and a spin injection\\/detection efficiency of 0.013. Electrical detection of the spin precession confirms that the nonlocal signal originates

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

2009-01-01

55

Quantum-dot-spin single-photon interface.  

PubMed

Using background-free detection of spin-state-dependent resonance fluorescence from a single-electron charged quantum dot with an efficiency of 0.1%, we realize a classical single spin-photon interface where the detection of a scattered photon with 300 ps time resolution projects the quantum dot spin to a definite spin eigenstate with fidelity exceeding 99%. The bunching of resonantly scattered photons reveals information about electron spin dynamics. High-fidelity fast spin-state initialization heralded by a single photon enables the realization of quantum information processing tasks such as nondeterministic distant spin entanglement. Given that we could suppress the measurement backaction to well below the natural spin-flip rate, realization of a quantum nondemolition measurement of a single spin could be achieved by increasing the fluorescence collection efficiency by a factor exceeding 10 using a photonic nanostructure. PMID:20867763

Yilmaz, S T; Fallahi, P; Imamo?lu, A

2010-07-16

56

Quantum-Dot-Spin Single-Photon Interface  

NASA Astrophysics Data System (ADS)

Using background-free detection of spin-state-dependent resonance fluorescence from a single-electron charged quantum dot with an efficiency of 0.1%, we realize a classical single spin-photon interface where the detection of a scattered photon with 300 ps time resolution projects the quantum dot spin to a definite spin eigenstate with fidelity exceeding 99%. The bunching of resonantly scattered photons reveals information about electron spin dynamics. High-fidelity fast spin-state initialization heralded by a single photon enables the realization of quantum information processing tasks such as nondeterministic distant spin entanglement. Given that we could suppress the measurement backaction to well below the natural spin-flip rate, realization of a quantum nondemolition measurement of a single spin could be achieved by increasing the fluorescence collection efficiency by a factor exceeding 10 using a photonic nanostructure.

Y?lmaz, S. T.; Fallahi, P.; Imamo?lu, A.

2010-07-01

57

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

58

Nanoscale single-electron transistor architectures for single spin detection in solid state quantum computer devices  

Microsoft Academic Search

Single-spin detection will be crucial for solid-state quantum computer architectures in which information is encoded in the spin-state of single nuclear or electron spins. The formidable problem of single-spin detection in a solid can be mapped to a more tractable problem of single-charge detection through spin-dependent electron transfer which may be observed using ultra-sensitive solid-state nanostructure electrometers. Here we describe

Tilo M. Buehler; Rolf Brenner; David J. Reilly; Alex R. Hamilton; Andrew S. Dzurak; Robert C. Clark

2001-01-01

59

Symmetry and Controllability for Quantum Spin Networks  

NASA Astrophysics Data System (ADS)

Symmetry is found to be an important tool to study the controllability problems in quantum control. Based on quantum spin networks subject to control of a single node by a local potential (Z-control), we have considered the relation of symmetriy and subspace controllability. Focusing on the single excitation subspace it is shown that for single-node Z-controls external symmetries are characterized by eigenstates of the system Hamiltonian that have zero overlap with the control node, and there are no internal symmetries. For uniformly coupled XXZ chains a characterization of all possible symmetries is derived from Bethe ansatz. Moreover, for uniform Heisenberg and XX chains, basic number theory can be used to prove that the lack of symmetry is equivalent to subspace controllability. On the other hand, symmetries in the Hamiltonian can be classified into two types: the internal and the external symmetries. Based on the external symmetries, we can rigorously prove the subspace controllability in each of the invariant subspaces for both XXZ and XYZ chains, but not for XX or Ising chains. All these results are useful to design the appropriate control strategy when implementing QIP in real physical systems.

Wang, Xiaoting; Schirmer, Sophie; Burgarth, Daniel; Pemberton-Ross, Peter; Jacobs, Kurt

2013-03-01

60

QCD Resummation for Single Spin Asymmetries  

SciTech Connect

We study the transverse momentum dependent factorization for single spin asymmetries in Drell-Yan and semi-inclusive deep inelastic scattering processes at one-loop order. The next-to-leading order hard factors are calculated in the Ji-Ma-Yuan factorization scheme. We further derive the QCD resummation formalisms for these observables following the Collins-Soper-Sterman method. The results are expressed in terms of the collinear correlation functions from initial and/or final state hadrons coupled with the Sudakov form factor containing all order soft-gluon resummation effects. The scheme-independent coefficients are calculated up to one-loop order.

Kang Zhongbo [RIKEN/BNL Research Center, Building 510A, Brookhaven National Laboratory, Upton, New York 11973 (United States); Xiao Bowen [Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Yuan Feng [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); RIKEN/BNL Research Center, Building 510A, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2011-10-07

61

Quantum physics: The right ambience for a single spin  

NASA Astrophysics Data System (ADS)

Long-lived single electron spins are crucial for quantum computation and for understanding spin dynamics. A remarkably long lifetime -- of the order of minutes -- has now been obtained for a solid-state system. See Letter p.242

Flatté, Michael E.

2013-11-01

62

Universal quantum computation using exchange interactions and measurements of single- and two-spin observables  

SciTech Connect

We show how to construct a universal set of quantum logic gates using control over exchange interactions and single- and two-spin measurements only. Single-spin unitary operations are teleported between neighboring spins instead of being executed directly, thus potentially eliminating a major difficulty in the construction of several of the most promising proposals for solid-state quantum computation, such as spin-coupled quantum dots, donor-atom nuclear spins in silicon, and electrons on helium. Contrary to previous proposals dealing with this difficulty, our scheme requires no encoding redundancy. We also discuss an application to superconducting phase qubits.

Wu, L.-A.; Lidar, Daniel A. [Chemical Physics Theory Group, Chemistry Department, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6 (Canada)

2003-05-01

63

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

64

Implementing controlled-NOT gate based on free spin qubits with semiconductor quantum-dot array  

NASA Astrophysics Data System (ADS)

Based on electron spins in semiconductor quantum dots as qubits, a new quantum controlled-NOT (CNOT) gate is constructed in solid nanostructure without resorting to spin-spin interactions. Single-electron tunneling technology and coherent quantum-dot cellular-automaton architecture are used to generate an ancillary charge entangled state. Using the ancillary charge entangled state as an intermediate state, we obtain a spin entangled state and design a CNOT gate by using only single-spin rotations.

Wu, Yin-Zhong; Zhang, Wei-Min

2005-08-01

65

Dynamically generated pure spin current in single-layer graphene  

NASA Astrophysics Data System (ADS)

The conductance mismatch problem limits the spin-injection efficiency significantly, and spin injection into graphene usually requires high-quality tunnel barriers to circumvent the conductance mismatch. We introduce an approach which enables the generation of pure spin current into single-layer graphene (SLG) that is free from electrical conductance mismatch by using dynamical spin injection. An experimental demonstration of spin-pumping-induced spin current generation and spin transport in SLG at room temperature was successfully achieved, and the spin coherence length was estimated to be 1.36 ?m by using a conventional theoretical model based on the Landau-Lifshitz-Gilbert equation. The spin coherence length is proportional to the quality of SLG, which indicates that spin relaxation in SLG is governed by the Elliot-Yafet mechanism, as was reported.

Tang, Zhenyao; Shikoh, Eiji; Ago, Hiroki; Kawahara, Kenji; Ando, Yuichiro; Shinjo, Teruya; Shiraishi, Masashi

2013-04-01

66

Single Spin Asymmetry in High Energy QCD  

NASA Astrophysics Data System (ADS)

We present the first steps in an effort to incorporate the physics of transverse spin asymmetries into the saturation formalism of high energy QCD. We consider a simple model in which a transversely polarized quark scatters on a proton or nuclear target. Using the light-cone perturbation theory the hadron production cross section can be written as a convolution of the light-cone wave function squared and the interaction with the target. To generate the single transverse spin asymmetry (STSA) either the wave function squared or the interaction with the target has to be T-odd. In this work we use the lowest-order q ? q G wave function squared, which is T-even, generating the STSA from the T-odd interaction with the target mediated by an odderon exchange. We study the properties of the obtained STSA, some of which are in qualitative agreement with experiment: STSA increases with increasing projectile xF and is a non-monotonic function of the transverse momentum kT. Our mechanism predicts that the quark STSA in polarized proton-nucleus collisions should be much smaller than in polarized proton-proton collisions. We also observe that the STSA for prompt photons due to our mechanism is zero within the accuracy of the approximation.

Kovchegov, Yuri V.; Sievert, Matthew D.

67

Controlling the quantum dynamics of a mesoscopic spin bath in diamond  

PubMed Central

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.

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

2012-01-01

68

Magnetic control of spin reorientation and magnetodielectric effect below the spin compensation temperature in TmFeO3  

NASA Astrophysics Data System (ADS)

The onset of antiferromagnetic transition, spin reorientation, and spin compensation of TmFeO3 single crystals were investigated by the magnetic and heat capacity measurements. Control of spin reorientation by magnetic field and anomalous hysteretic behavior in domain switching were clarified. No appreciable magnetodielectric effect was observed in spin reorientation temperature region. On the other hand, below the spin compensation temperature both a dielectric anomaly along the c axis and a concomitant magnetodielectric effect up to ~4% at 80 kOe were observed. This suggests that rare-earth orthoferrites can be another candidate for magnetodielectric system through the mediation of spin compensation phenomena.

Muralidharan, R.; Jang, T.-H.; Yang, C.-H.; Jeong, Y. H.; Koo, T. Y.

2007-01-01

69

RHIC spin flipper AC dipole controller  

SciTech Connect

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

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

2011-03-28

70

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

71

Optically driven Rabi oscillations and adiabatic passage of single electron spins in diamond.  

PubMed

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. PMID:24702393

Golter, D Andrew; Wang, Hailin

2014-03-21

72

Electric field control of spin transport  

Microsoft Academic Search

Spintronics aims to develop electronic devices whose resistance is controlled by the spin of the charge carriers that flow through them. This approach is illustrated by the operation of the most basic spintronic device, the spin valve, which can be formed if two ferromagnetic electrodes are separated by a thin tunnelling barrier. In most cases, its resistance is greater when

Sangeeta Sahoo; Takis Kontos; Jürg Furer; Christian Hoffmann; Matthias Gräber; Audrey Cottet; Christian Schönenberger

2005-01-01

73

Mechanism for electric field driven single spin manipulation of a Mn dopant in GaAs  

NASA Astrophysics Data System (ADS)

We show that the spin orientation of a J=1 (Mn + hole) complex in GaAs can be manipulated using only electrical control fields. The spin degeneracy of the compound spin can be split by a dc electric field due to inversion symmetry breaking. The resonances, corresponding to transitions between the split levels, can be driven by an ac electric field. As the bound hole has an anisotropic shape that depends on the compound spin orientation, we propose that the resonance of a single spin can be detected in the tunneling current with scanning tunneling microscopy. The visibility of the resonance is high, as the total (not spin-resolved) local density of states can change as much as 90% for sites near the Mn dopant as the compound spin orientation is changed. This work is supported by ARO MURI DAAD19-01-1-0541 and DARPA QuIST DAAD-19-01-1-0650.

Tang, Jian-Ming; Levy, Jeremy; Flatté, Michael E.

2005-03-01

74

Ultrafast optical entanglement control between two quantum dot spins  

NASA Astrophysics Data System (ADS)

A single electron spin in an InAs quantum dot is very attractive as a qubit since this system is potentially scalable and allows complete quantum control on an ultrafast timescale using optical pulses. While great progress has been achieved with single spin qubits, it is essential for quantum information applications to move toward entangled multi-qubit systems. Two-qubit systems have been studied in electrostatically-defined quantum dots, but their optical functionality remains unexplored. Here we demonstrate ultrafast optical control of two interacting qubits consisting of two electron spins in separate InAs dots. We initialize the system into a spin singlet state using a cw laser. We then manipulate the entangled state of the two spins with single qubit gates (acting only on one spin) by using pulses faster than the exchange interaction. This allows us to generate all four Bell states. Two-qubit gates are obtained either by the natural exchange precession or by using a longer laser pulse that induces a phase shift in the precession. The two-qubit exchange rate (30 GHz) here gives SWAP gate times of 16 ps, the fastest of any candidate for quantum information processing.

Carter, Sam; Kim, Danny; Greilich, Alex; Bracker, Allan; Gammon, Daniel

2011-03-01

75

Electrons trapped in single crystals of sucrose: Induced spin densities  

SciTech Connect

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

Box, H.C.; Budzinski, E.E.; Freund, H.G. (Biophysics Department, Roswell Park Memorial Institute, Buffalo, New York 14263 (USA))

1990-07-01

76

Spin and charge transport study in single crystal organic semiconductors  

NASA Astrophysics Data System (ADS)

Spin transport studies in amorphous rubrene films have shown exciting and promising results [1]. A large spin diffusion length in these amorphous films has increased the motivation to perform spin transport study in high purity single crystal rubrene. This will provide the fundamental understanding on the spin transport behavior in OS; not influenced by defects or traps. We will present work on small channel single crystal rubrene FET device with magnetic electrodes. For example, our preliminary studies have show mobility for FET with Co electrode to be 0.014cm^2/V-s. A study on the spin and charge transport properties in single crystals of OS with magnetic electrodes is being done and the results will be reported. The influence of gate voltage and applied magnetic field on the transport properties will be discussed. [1] J.H. Shim et al., PRL 100, 226603 (2008)

Raman, Karthik V.; Mulder, Carlijn L.; Baldo, Marc A.; Moodera, Jagadeesh S.

2009-03-01

77

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

78

Searching for spin coherence in single quantum dots  

Microsoft Academic Search

Quantum dots form the basis of many spin-based quantum computing architectures, yet the transverse coherence time T2 of a single electron spin in a quantum dot has not been measured. These measurements are challenging, due to the relatively weak interaction with light and the difficulty of resolving signatures from large ensembles of quantum dots. We describe our efforts to isolate

Petru Fodor; Gilberto Medeiros-Ribeiro; Jeremy Levy

2004-01-01

79

NMR excitation and relaxation in a ``single domain'' spin glass  

Microsoft Academic Search

Zero field NMR measurements of the spin lattice relaxation time T1 on copper satellite nuclei in a frozen CuMn ``single domain'' spin glass show that the longitudinal nuclear magnetization recovery is not purely exponential. Three possible causes for the observed nonexponentiality have been considered: The distribution of enhancement factors, the differences in neighbourhood experienced by the satellite nuclei and a

E. Tönsing; H. Jung; C. Tempelmann; H. Brömer

1991-01-01

80

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

PubMed Central

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

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

2013-01-01

81

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

PubMed

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

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

2013-07-01

82

Collins Fragmentation and the Single Transverse Spin Asymmetry  

SciTech Connect

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

Yuan, Feng; Zhou, Jian

2009-03-26

83

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

84

Quantum Entanglement and Spin Control in Silicon Nanocrystal  

PubMed Central

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

Berec, Vesna

2012-01-01

85

Coherent properties of single rare-earth spin qubits.  

PubMed

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

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

2014-01-01

86

Coherent properties of single rare-earth spin qubits  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

87

Attitude orientation control for a spinning satellite  

NASA Astrophysics Data System (ADS)

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

Frost, Gerald

88

Spectral control of spin qubits in diamond photonic structures  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

89

Room-temperature entanglement between single defect spins in diamond  

NASA Astrophysics Data System (ADS)

Entanglement is the central yet fleeting phenomenon of quantum physics. Once being considered a peculiar counter-intuitive property of quantum theory, it has developed into the most central element of quantum technology. Consequently, there have been a number of experimental demonstrations of entanglement between photons, atoms, ions and solid-state systems such as spins or quantum dots, superconducting circuits and macroscopic diamond. Here we experimentally demonstrate entanglement between two engineered single solid-state spin quantum bits (qubits) at ambient conditions. Photon emission of defect pairs reveals ground-state spin correlation. Entanglement (fidelity=0.67+/-0.04) is proved by quantum state tomography. Moreover, the lifetime of electron spin entanglement is extended to milliseconds by entanglement swapping to nuclear spins. The experiments mark an important step towards a scalable room-temperature quantum device being of potential use in quantum information processing as well as metrology.

Dolde, F.; Jakobi, I.; Naydenov, B.; Zhao, N.; Pezzagna, S.; Trautmann, C.; Meijer, J.; Neumann, P.; Jelezko, F.; Wrachtrup, J.

2013-03-01

90

Nondemolition measurements of a single quantum spin using Josephson oscillations.  

PubMed

We consider a single localized spin-1/2 between the singlet superconducting leads of a Josephson junction (e.g., a superconducting STM). For the spin subject to a dc magnetic field B parallel z, we study the spin dynamics and the possibility to measure the spin state via transport through the junction embedded in a dissipative circuit. Turning on the tunneling or a voltage bias induces oscillations of the Josephson current, with an amplitude sensitive to the initial value of the z component of the spin, S(z)=+/-1/2. At low temperatures, when effects of quasiparticles are negligible, this procedure realizes a quantum nondemolition measurement of S(z). PMID:15169182

Bulaevskii, L; Hruska, M; Shnirman, A; Smith, D; Makhlin, Yu

2004-04-30

91

K-band single-chip electron spin resonance detector.  

PubMed

We report on the design, fabrication, and characterization of an integrated detector for electron spin resonance spectroscopy operating at 27 GHz. The microsystem, consisting of an LC-oscillator and a frequency division module, is integrated onto a single silicon chip using a conventional complementary metal-oxide-semiconductor technology. The achieved room temperature spin sensitivity is about 10(8)spins/G Hz(1/2), with a sensitive volume of about (100 ?m)(3). Operation at 77K is also demonstrated. PMID:22405529

Anders, Jens; Angerhofer, Alexander; Boero, Giovanni

2012-04-01

92

Spin-transfer torque in a single ferromagnet  

NASA Astrophysics Data System (ADS)

A spin polarized current, with sufficiently high current density, is able to switch a magnet or induce magnetization precession. This is the consequence of the ¡°spin-transfer torque¡+/- that originates from spin angular momentum transfer between conduction electrons and the magnetization. Previously most theories and experiments explore F/N/F trilayer and F/N multilayer structures, where F denotes a ferromagnet and N denotes a nonmagnetic metal. These structures have been generally presumed indispensable, since non-collinear magnetizations between a polarizing layer and a free layer are required to generate spin torques, and the GMR effect is essential in detecting magnetization variations. In this work, spin-transfer torque effects in a single ferromagnetic layer are demonstrated, using current injection through a point-contact at 4.2 K. Firstly, differential resistance peaks, generally regarded as signatures of spin-wave excitations, are observed in a single ferromagnetic layer in high magnetic fields [1]. The current values corresponding to the peak positions linearly depend on the external field in the range of 2 to 9 Tesla. Secondly, hysteretic current-induced switching is observed in a single ferromagnet in low magnetic fields. Both experiments can be interpreted by a simple model based on heterogeneous current distribution and domain wall scattering. Systematic variations between low field and high field regions have been investigated and the implications will be discussed. [1] Y. Ji, C. L. Chien and M. D. Stiles, Phys. Rev. Lett. 90, 106601 (2003)

Ji, Yi

2004-03-01

93

Nanoscale magnetometry using a single-spin system in diamond  

NASA Astrophysics Data System (ADS)

We propose a protocol to estimate magnetic fields using a single nitrogen-vacancy (N-V) center in diamond, where the estimate precision scales inversely with time, ?B~1/T, rather than the square-root of time, ?B~1/T. The method is based on converting the task of magnetometry into phase estimation, performing quantum phase estimation on a single N-V nuclear spin using either adaptive or nonadaptive feedback control, and the recently demonstrated capability to perform single-shot readout within the N-V [P. Neumann , ScienceSCIEAS0036-807510.1126/science.1189075 329, 542 (2010)]. We present numerical simulations to show that our method provides an estimate whose precision scales close to ~1/T (T~ the total estimation time), and moreover will give an unambiguous estimate of the static magnetic field experienced by the N-V. By combining this protocol with recent proposals for scanning magnetometry using an N-V, our protocol will provide a significant decrease in signal acquisition time while providing an unambiguous spatial map of the magnetic field.

Said, R. S.; Berry, D. W.; Twamley, J.

2011-03-01

94

Coherent dynamics of a single spin interacting with an adjustable spin bath.  

PubMed

Phase coherence is a fundamental concept in quantum mechanics. Understanding the loss of coherence is paramount for future quantum information processing. We studied the coherent dynamics of a single central spin (a nitrogen-vacancy center) coupled to a bath of spins (nitrogen impurities) in diamond. Our experiments show that both the internal interactions of the bath and the coupling between the central spin and the bath can be tuned in situ, allowing access to regimes with surprisingly different behavior. The observed dynamics are well explained by analytics and numerical simulations, leading to valuable insight into the loss of coherence in spin systems. These measurements demonstrate that spins in diamond provide an excellent test bed for models and protocols in quantum information. PMID:18339902

Hanson, R; Dobrovitski, V V; Feiguin, A E; Gywat, O; Awschalom, D D

2008-04-18

95

Nanomagnetism: Spin doctors play with single electrons  

Microsoft Academic Search

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.

Steven C. Erwin

2006-01-01

96

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

97

Single electron-spin memory with a semiconductor quantum dot  

NASA Astrophysics Data System (ADS)

We show storage of the circular polarization 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 read out through the electronically-triggered emission of a single photon. The emitted photon shares the same polarization 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 T, spin memory is preserved for at least 1000 times more than the exciton's radiative lifetime.

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

2007-10-01

98

Control of magnetic fluctuations by spin current.  

PubMed

We use microfocus Brillouin light scattering spectroscopy to study the interaction of spin current with magnetic fluctuations in a Permalloy microdisk located on top of a Pt strip carrying an electric current. We show that the fluctuations can be efficiently suppressed or enhanced by different directions of the electric current. Additionally, we find that the effect of spin current on magnetic fluctuations is strongly influenced by nonlinear magnon-magnon interactions. The observed phenomena can be used for controllable reduction of thermal noise in spintronic nanodevices. PMID:21981525

Demidov, V E; Urazhdin, S; Edwards, E R J; Stiles, M D; McMichael, R D; Demokritov, S O

2011-09-01

99

Quantum Interference Control of Ballistic Pure Spin Currents in Semiconductors.*  

NASA Astrophysics Data System (ADS)

One of the main obstacles to the development of spintronic devices is the difficulty in injecting and controlling spin currents in semiconductors, especially in the absence of charge currents. Our approach has been to exploit nonlinear optical processes and quantum interference effects to control electron properties in common semiconductors such as GaAs. We have typically employed 150 fs pulses at 1550 nm and 775 nm and used interference between single photon and two-photon absorption pathways to generate and control spin or electrical currents through the relative phase of the beams. Maximum electrical currents are generated when both beams are co-linearly polarized along the [111] direction (bond direction between Ga and As). However, with orthogonally, linearly polarized beams incident collinearly on any surface of GaAs it is possible to generate ballistic spin currents along the polarization direction of the 1550 nm beam [1]. These currents are generated in the absence of electrical currents. With other polarization combinations and crystal orientations it is possible to generate spin currents with or without electrical currents, and electrical currents with or without spin currents. In another configuration the 1550 and 775 nm pulses are incident non-collinearly on GaAs producing pure spin current gratings in bulk [100]-oriented GaAs; the relative phase between the beams and therefore the amplitude of the spin current is modulated periodically across the sample. Through the generation of various types of spin, electrical and spin/electrical current gratings we are able to observe the ballistic as well as diffusive transport characteristics of these currents. [1] M.J. Stevens, A.L. Smirl, R. Bhat, A. Najmaie, J.Sipe and H.M. van Driel, Quantum Inteference Control of Ballistic Pure Spin Currents in Semiconductors, Phys. Rev. Lett. 90, 136603-1(2003). * Work performed in collaboration with J. Sipe, R. Bhat and Y. Kerachian (University of Toronto) and A. Smirl, M. Stevens (University of Iowa) and funded by NSERC, Photonics Research Ontario and the DARPA Spintronics Program.

van Driel, Henry

2004-03-01

100

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

101

Calculation of TMD Evolution for Transverse Single Spin Asymmetry Measurements  

Microsoft Academic Search

In this letter, we show that it is necessary to include the full treatment of QCD evolution of Transverse Momentum Dependent parton densities to explain discrepancies between HERMES data and recent COMPASS data on a proton target for the Sivers transverse single spin asymmetry in Semi-Inclusive Deep Inelastic Scattering (SIDIS). Calculations based on existing fits to TMDs in SIDIS, and

Mert Aybat; Ted Rogers; Alexey Prokudin

2012-01-01

102

Quantum nondemolition measurements of single donor spins in semiconductors  

NASA Astrophysics Data System (ADS)

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

Sarovar, Mohan; Young, Kevin C.; Schenkel, Thomas; Whaley, K. Birgitta

2008-12-01

103

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

104

Nonlinear Single-Spin Spectrum Analyzer  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

105

Single-shot readout of spin qubits in Si/SiGe quantum dots  

NASA Astrophysics Data System (ADS)

Si/SiGe quantum dots are an attractive option for spin qubit development, because of the long coherence times for electron spins in silicon, arising from weak hyperfine interaction and low spin orbit coupling. I will present measurements of gate-defined single and double quantum dots formed in Si/SiGe semiconductor heterostuctures. Control of the gate voltages on these dots enables tuning of the tunnel coupling to the leads and to other dots. Careful tuning of these tunnel rates, in combination with fast, pulsed-gate manipulation and spin-to-charge conversion, allow spin state measurement using an integrated quantum point contact as a local charge detector. Single spin qubit readout relies on the Zeeman energy splitting from an external magnetic field for spin-to-charge conversion. Two-electron singlet-triplet qubits, on the other hand, can be measured by using Pauli spin blockade of tunneling between the dots to readout the qubit even at zero magnetic field. I will present real-time, single-shot readout measurements of both individual spin [1] and singlet-triplet qubits [2] in gated Si/SiGe quantum dots. Work performed in collaboration with J. R. Prance, Zhan Shi, B. J. Van Bael, Teck Seng Koh, D. E. Savage, M. G. Lagally, R. Joynt, L. R. Schreiber, L. M. K. Vandersypen, M. Friesen, S. N. Coppersmith, and M. A. Eriksson. [4pt] [1] C. B. Simmons et al. Physical Review Letters 106, 156804 (2011). [0pt] [2] J. R. Prance, et al., e-print: http://lanl.arxiv.org/abs/1110.6431

Simmons, Christie

2012-02-01

106

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

PubMed

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

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

2011-09-30

107

Coherent spin control by electromagnetic vacuum fluctuations  

SciTech Connect

In coherent control, electromagnetic vacuum fluctuations usually cause coherence loss through irreversible spontaneous emission. However, since the dissipation via emission is essentially due to correlation of the fluctuations, when emission ends in a superposition of multiple final states, correlation between different pathways may build up if the 'which way' information is not fully resolved (i.e., the emission spectrum is broader than the transition energy range). Such correlation can be exploited for spin-flip control in a {Lambda}-type three-level system, which manifests itself as an all-optical spin echo in nonlinear optics with two orders of optical fields saved as compared with stimulated Raman processes. This finding represents a class of optical nonlinearity induced by electromagnetic vacuum fluctuations.

Wang Jing [Department of Physics, Chinese University of Hong Kong, Shatin, N.T. (Hong Kong); Department of Physics, Tsinghua University, Beijing 100084 (China); Liu Renbao [Department of Physics, Chinese University of Hong Kong, Shatin, N.T. (Hong Kong); Zhu Bangfen [Department of Physics, Tsinghua University, Beijing 100084 (China); Institute of Advanced Study, Tsinghua University, Beijing 100084 (China); Sham, L. J. [Department of Physics, University of California-San Diego, La Jolla, California 92093-0319 (United States); Steel, D. G. [H. M. Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2011-05-15

108

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

109

Controllable effects of quantum fluctuations on spin free-induction decay at room temperature.  

PubMed

Fluctuations of local fields cause decoherence of quantum objects. Usually at high temperatures, thermal noises are much stronger than quantum fluctuations unless the thermal effects are suppressed by certain techniques such as spin echo. Here we report the discovery of strong quantum-fluctuation effects of nuclear spin baths on free-induction decay of single electron spins in solids at room temperature. We find that the competition between the quantum and thermal fluctuations is controllable by an external magnetic field. These findings are based on Ramsey interference measurement of single nitrogen-vacancy center spins in diamond and numerical simulation of the decoherence, which are in excellent agreement. PMID:22666535

Liu, Gang-Qin; Pan, Xin-Yu; Jiang, Zhan-Feng; Zhao, Nan; Liu, Ren-Bao

2012-01-01

110

Controllable effects of quantum fluctuations on spin free-induction decay at room temperature  

PubMed Central

Fluctuations of local fields cause decoherence of quantum objects. Usually at high temperatures, thermal noises are much stronger than quantum fluctuations unless the thermal effects are suppressed by certain techniques such as spin echo. Here we report the discovery of strong quantum-fluctuation effects of nuclear spin baths on free-induction decay of single electron spins in solids at room temperature. We find that the competition between the quantum and thermal fluctuations is controllable by an external magnetic field. These findings are based on Ramsey interference measurement of single nitrogen-vacancy center spins in diamond and numerical simulation of the decoherence, which are in excellent agreement.

Liu, Gang-Qin; Pan, Xin-Yu; Jiang, Zhan-Feng; Zhao, Nan; Liu, Ren-Bao

2012-01-01

111

Single-Spin Asymmetries in SIDIS at JLab  

NASA Astrophysics Data System (ADS)

Measurements of spin and azimuthal asymmetries in semi-inclusive processes emerged as an important tool to access Transverse Momentum Dependent (TMD) parton distributions containing information on both the longitudinal and transverse motion of partons inside a fast moving nucleon. CLAS collaboration at Jefferson Lab collected recently approximately 19 billion electron triggers with hydrogen and 7 billion electron triggers with deuterium using solid state ammonia and deuterated ammonia targets. Kinematical dependences of single and double spin asymmetries have been measured for a longitudinally polarized proton target, providing access to transverse momentum distributions of quarks and spin orbit correlations in the nucleon. In this talk we present latest studies of TMDs and discuss newly released results, ongoing activities, as well as planed near term and future measurements.

Avagyan, Harut

2012-03-01

112

Single-chip detector for electron spin resonance spectroscopy  

SciTech Connect

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

Yalcin, T. [Hochschule fuer Technik und Architektur Luzern (HTA), 6048 Horw (Switzerland); Ecole Polytechninque Federale de Lausanne (EPFL), 1015 Lausanne (Switzerland); Boero, G. [Ecole Polytechninque Federale de Lausanne (EPFL), 1015 Lausanne (Switzerland)

2008-09-15

113

Single-chip detector for electron spin resonance spectroscopy.  

PubMed

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

Yalcin, T; Boero, G

2008-09-01

114

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

115

Electric-field sensing using single diamond spins  

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

116

Single-spin superconductivity: Formulation and Ginzburg-Landau theory  

Microsoft Academic Search

We describe a superconducting phase that arises due to a pairing instability of the half-metallic antiferromagnetic (HM AFM) normal state. This single-spin superconducting (SSS) phase contains broken time-reversal symmetry in addition to broken gauge symmetry, the former due to the underlying magnetic order in the normal state. A classification of normal-state symmetries leads to the conclusion that the HM AFM

Robert E. Rudd; Warren E. Pickett

1998-01-01

117

Single transverse-spin asymmetry in hadronic dijet production  

Microsoft Academic Search

We study the single-transverse-spin asymmetry for dijet production in hadronic collisions in both the collinear QCD factorization approach and the Brodsky-Hwang-Schmidt model. We show that a nonvanishing asymmetry is generated by both initial-state and final-state interactions, and that the final-state interactions dominate. We find that in the leading kinematic region where the transverse momentum imbalance of the two jets, q-vector{sub

Jian-Wei Qiu; Werner Vogelsang; Feng Yuan

2007-01-01

118

Single transverse-spin asymmetry in hadronic dijet production  

Microsoft Academic Search

We study the single-transverse-spin asymmetry for dijet production in hadronic collisions in both the collinear QCD factorization approach and the Brodsky-Hwang-Schmidt model. We show that a nonvanishing asymmetry is generated by both initial-state and final-state interactions, and that the final-state interactions dominate. We find that in the leading kinematic region where the transverse momentum imbalance of the two jets, q-->?=P-->1?+P-->2?,

Jian-Wei Qiu; Werner Vogelsang; Feng Yuan

2007-01-01

119

Towards force detected single electron spin resonance at room temperature  

NASA Astrophysics Data System (ADS)

Electrically detected magnetic resonance (EDMR) spectroscopy has shown that electron tunneling at or within silicon dioxide layers is strongly dependent on spin-selection rules [1]. Also demonstrated is the detection of single electron tunneling events by electrostatic force with sub-nanometer spatial resolution [2,3]. Here we propose to combine force detected single electron tunneling microscopy with EDMR to demonstrate a new kind of single spin force microscope. This approach has much better sensitivity than magnetic force based single spin microscopes [4], since electrostatic forces are much larger than corresponding magnetic forces. In this method, a paramagnetic state in an oxidized AFM probe tip is brought within tunneling range of a paramagnetic state in an oxide surface [5]. Under appropriate energy conditions, one of the unpaired electrons can randomly tunnel between the two states causing a random telegraph signal (RTS) to appear on the AFM cantilever frequency. Simulations predict that if magnetic resonance conditions are achieved, a measurable change in the RTS signal is detectable at room temperature. The theory and a quantitative simulation of this atomic scale spin resonance measurement will be presented, along with experimentally observed random telegraph signals.[4pt] [1] D. R. McCamey, et al., Phys. Rev. B, 78, 045302 (2008). [2] L. J. Klein and C.C. Williams, Appl. Phys. Lett. 79, 1828 (2001). [3] E. Bussmann and D.J. Kim, and C.C. Williams, Appl. Phys. Lett. 85, 2538 (2004). [4] D. Rugar et al., Nature 430, 329 (2004). [5] J.P. Johnson, Ph.D. Thesis, Dept. of Physics, University of Utah (2010).

Williams, C. C.; Payne, A.; Ambal, K.; Boehme, C.

2013-03-01

120

High fidelity readout of a single electron spin  

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

121

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

122

Ultrafast optical control of interacting hole spins in coupled quantum dots  

NASA Astrophysics Data System (ADS)

Recently, hole spins in quantum dots (QDs) have shown great promise as quantum bits due to a reduced hyperfine interaction with nuclear spins, the primary source of decoherence for electron spins. We have developed a system of two vertically stacked InAs QDs that can be charged with a number of holes. In this way, an isolated hole in one QD or two interacting holes in separate dots can be studied. We demonstrate ultrafast optical control of both systems and find a number of differences compared to electron spins. Complete control of the single hole qubit is obtained through optical initialization and single qubit rotations. These control measurements give a hole spin T2^* of 20ns, an order of magnitude longer than electrons in similar QDs. Spin echo experiments extend the coherence time but are complicated by oscillations in the echo amplitude. For the case of two hole spins, we can observe and tune the coherent exchange interaction that acts as a two qubit gate. We also initialize and perform gates on an entangled spin state, taking a significant step toward a scalable platform for quantum information processing. [1] ``Optical control of one and two hole spins in interacting quantum dots,'' A. Greilich, S. G. Carter, D. Kim, A. S. Bracker and D. Gammon. Nature Photon.5, 702 (2011).

Carter, Samuel; Greilich, Alex; Kim, Danny; Bracker, Allan; Gammon, Daniel

2012-02-01

123

Single transverse-spin asymmetry in hadronic dijet production  

NASA Astrophysics Data System (ADS)

We study the single-transverse-spin asymmetry for dijet production in hadronic collisions in both the collinear QCD factorization approach and the Brodsky-Hwang-Schmidt model. We show that a nonvanishing asymmetry is generated by both initial-state and final-state interactions, and that the final-state interactions dominate. We find that in the leading kinematic region where the transverse momentum imbalance of the two jets, q??=P?1?+P?2?, is much less than the momentum of either jet, the contribution from the lowest nontrivial perturbative order to both the spin-averaged and the spin-dependent dijet cross sections can be factorized into a hard part that is a function only of the averaged jet momentum P??=(P?1?-P?2?)/2, and perturbatively generated transverse momentum dependent (TMD) parton distributions. We show that the spin asymmetry at this nontrivial perturbative order can be described by the TMD parton distributions defined in either semi-inclusive deep inelastic scattering or the Drell-Yan process. We derive the same hard parts from both the collinear factorization approach and in the context of the Brodsky-Hwang-Schmidt model, verifying that they are not sensitive to details of the factorized long-distance physics.

Qiu, Jian-Wei; Vogelsang, Werner; Yuan, Feng

2007-10-01

124

Single transverse-spin asymmetry in hadronic dijet production  

SciTech Connect

We study the single-transverse-spin asymmetry for dijet production in hadronic collisions in both the collinear QCD factorization approach and the Brodsky-Hwang-Schmidt model. We show that a nonvanishing asymmetry is generated by both initial-state and final-state interactions, and that the final-state interactions dominate. We find that in the leading kinematic region where the transverse momentum imbalance of the two jets, q-vector{sub perpendicular}=P-vector{sub 1perpendicular}+P-vector{sub 2perpendicular}, is much less than the momentum of either jet, the contribution from the lowest nontrivial perturbative order to both the spin-averaged and the spin-dependent dijet cross sections can be factorized into a hard part that is a function only of the averaged jet momentum P-vector{sub perpendicular}=(P-vector{sub 1perpendicular}-P-vector{sub 2perpendicular})/2, and perturbatively generated transverse momentum dependent (TMD) parton distributions. We show that the spin asymmetry at this nontrivial perturbative order can be described by the TMD parton distributions defined in either semi-inclusive deep inelastic scattering or the Drell-Yan process. We derive the same hard parts from both the collinear factorization approach and in the context of the Brodsky-Hwang-Schmidt model, verifying that they are not sensitive to details of the factorized long-distance physics.

Qiu, Jian-Wei [Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Vogelsang, Werner [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Yuan, Feng [RIKEN BNL Research Center, Building 510A, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2007-10-01

125

Spin Anisotropy Effects in Dimer Single Molecule Magnets  

NASA Astrophysics Data System (ADS)

We present a model of equal spin s1 dimer single molecule magnets. The spins within each dimer interact via the Heisenberg and the most general set of four quadratic anisotropic spin interactions with respective strengths J and Jj, and with the magnetic induction B. For antiferromagnetic Heisenberg couplings (J<0) and weak anisotropy interactions (|Jj/J|1), the low temperature T magnetization M(B) exhibits 2s1 steps, the height and midpoint slope of the sth step differing from their isotropic limits by corrections of O(Jj/J)^2, but the position occurring at the energy level-crossing magnetic induction Bs,s1^lc(,), where , define the direction of B. We solve the model exactly for s1=1/2, 1, and 5/2. For weakly anisotropic dimers, the Hartree approximation yields analytic formulas for M(B) and CV(B) at arbitrary s1 that accurately fit the exact solutions at sufficiently low T or large B. Low-T formulas for the inelastic neutron scattering S(q,?) and the EPR ?(?) in an extended Hartree approximation are given. Our results are discussed with regard to existing experiments on s1=5/2 Fe2 dimers, suggesting further experiments on single crystals of these and some s1=9/2 [Mn4]2 dimers are warranted.

Efremov, Dmitri; Klemm, Richard

2006-03-01

126

Mechanical spin control of nitrogen-vacancy centers in diamond.  

PubMed

We demonstrate direct coupling between phonons and diamond nitrogen-vacancy (NV) center spins by driving spin transitions with mechanically generated harmonic strain at room temperature. The amplitude of the mechanically driven spin signal varies with the spatial periodicity of the stress standing wave within the diamond substrate, verifying that we drive NV center spins mechanically. These spin-phonon interactions could offer a route to quantum spin control of magnetically forbidden transitions, which would enhance NV-based quantum metrology, grant access to direct transitions between all of the spin-1 quantum states of the NV center, and provide a platform to study spin-phonon interactions at the level of a few interacting spins. PMID:24329469

MacQuarrie, E R; Gosavi, T A; Jungwirth, N R; Bhave, S A; Fuchs, G D

2013-11-27

127

Fluorescence and spin properties of defects in single digit nanodiamonds.  

PubMed

This article reports stable photoluminescence and high-contrast optically detected electron spin resonance (ODESR) from single nitrogen-vacancy (NV) defect centers created within ultrasmall, disperse nanodiamonds of radius less than 4 nm. Unexpectedly, the efficiency for the production of NV fluorescent defects by electron irradiation is found to be independent of the size of the nanocrystals. Fluorescence lifetime imaging shows lifetimes with a mean value of around 17 ns, only slightly longer than the bulk value of the defects. After proper surface cleaning, the dephasing times of the electron spin resonance in the nanocrystals approach values of some microseconds, which is typical for the type Ib diamond from which the nanoparticle is made. We conclude that despite the tiny size of these nanodiamonds the photoactive nitrogen-vacancy color centers retain their bulk properties to the benefit of numerous exciting potential applications in photonics, biomedical labeling, and imaging. PMID:21452865

Tisler, Julia; Balasubramanian, Gopalakrishnan; Naydenov, Boris; Kolesov, Roman; Grotz, Bernhard; Reuter, Rolf; Boudou, Jean-Paul; Curmi, Patrick A; Sennour, Mohamed; Thorel, Alain; Börsch, Michael; Aulenbacher, Kurt; Erdmann, Rainer; Hemmer, Philip R; Jelezko, Fedor; Wrachtrup, Jörg

2009-07-28

128

Gigahertz electron spin manipulation using voltage-controlled g-tensor modulation.  

PubMed

We present a scheme that enables gigahertz-bandwidth three-dimensional control of electron spins in a semiconductor heterostructure with the use of a single voltage signal. Microwave modulation of the Landé g tensor produces frequency-modulated electron spin precession. Driving at the Larmor frequency results in g-tensor modulation resonance, which is functionally equivalent to electron spin resonance but without the use of time-dependent magnetic fields. These results provide proof of the concept that quantum spin information can be locally manipulated with the use of high-speed electrical circuits. PMID:12543982

Kato, Y; Myers, R C; Driscoll, D C; Gossard, A C; Levy, J; Awschalom, D D

2003-02-21

129

Reducing quantum control for spin-spin entanglement distribution  

NASA Astrophysics Data System (ADS)

We present a protocol that sets maximum stationary entanglement between remote spins through scattering of mobile mediators without initialization, post-selection or feedback of the mediators' state. No time-resolved tuning is needed and, counterintuitively, the protocol generates two-qubit singlet states even when classical mediators are used. The mechanism responsible for this effect is resilient against non-optimal coupling strengths and dephasing affecting the spins. The scheme uses itinerant particles and scattering centres and can be implemented in various settings. When quantum dots and photons are used a striking result is found: injection of classical mediators, rather than quantum ones, improves the scheme efficiency.

Ciccarello, F.; Paternostro, M.; Palma, G. M.; Zarcone, M.

2009-11-01

130

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

PubMed

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-?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)(? = 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-?m quantum channels. PMID:23262701

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

131

Imaging and controlling spins in semiconductors and ferromagnets  

NASA Astrophysics Data System (ADS)

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

Nowakowski, Mark Edward

132

Dynamics of a Single Spin-1/2 Coupled to x- and y-Spin Baths: Algorithm and Results  

NASA Astrophysics Data System (ADS)

The real-time dynamics of a single spin-1/2 particle, called the central spin, coupled to the x(y)-components of the spins of one or more baths is simulated. The bath Hamiltonians contain interactions of x(y)-components of the bath spins only but are general otherwise. An efficient algorithm is described which allows solving the time-dependent Schr’odinger equation for the central spin, even if the x(y) baths contain hundreds of spins. The algorithm requires storage for 2 × 2 matrices only, no matter how many spins are in the baths. We calculate the expectation value of the central spin, as well as its von Neumann entropy S(t), the quantum purity P(t), and the off-diagonal elements of the quantum density matrix. In the case of coupling the central spin to both x- and y- baths the relaxation of S(t) and P(t) with time is a power law, compared to an exponential if the central spin is only coupled to an x-bath. The effect of different initial states for the central spin and bath is studied. Comparison with more general spin baths is also presented.

Novotny, M. A.; Guerra, Marta L.; De Raedt, Hans; Michielsen, Kristel; Jin, Fengping

133

Reconfigurable Logic Gates Using Single-Electron Spin Transistors  

NASA Astrophysics Data System (ADS)

We propose and numerically analyze novel reconfigurable logic gates using “single-electron spin transistors” (SESTs), which are single-electron transistors (SETs) with ferromagnetic electrodes and islands. The output characteristics of a SEST depend on the relative magnetization configuration of the ferromagnetic island with respect to the magnetization of the source and the drain, i.e., high current drive capability in parallel magnetization and low current drive capability in antiparallel magnetization. The summation of multiple input signals can be achieved by directly coupling multiple input gate electrodes to the SEST island, without using a floating gate. A Tucker-type inverter with a variable threshold voltage, a reconfigurable AND/OR logic gate, and a reconfigurable logic gate for all symmetric Boolean functions are proposed and simulated using the Monte Carlo method.

Hai, Pham Nam; Sugahara, Satoshi; Tanaka, Masaaki

2007-10-01

134

Ferroelectric control of the spin polarization in an organic spin valve  

NASA Astrophysics Data System (ADS)

Recently engineering the spin propagation in organic spin valves has shown increasingly interesting properties. In this work we demonstrate novel ferroelectric control of the spin polarization in an organic spin valve. By inserting a thin ferroelectric buffer layer between a bottom La0.67Sr0.33MnO3 (LSMO) electrode and the organic Alq3 layer, a controlled spin polarization through the ferroelectric interface is achieved. The spin valve exhibits both positive and negative magnetoresistance depending on the applied bias. We conclude that this results from the energy level shift by the ferroelectric dipoles between Alq3 and LSMO (Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. Department of Energy).

Sun, Dali; Xu, Xiaoshan; Jiang, Lu; Lee, Ho Nyung; Guo, Hangwen; Snijders, Paul C.; Zac Ward, T.; Gai, Zheng; Zhang, X.-G.; Shen, Jian

2012-02-01

135

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

136

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

137

Geometric control of quantum spin systems  

NASA Astrophysics Data System (ADS)

Recent papers by Khaneja, Brockett and Glaser obtained efficient RF pulse trains for two-spin and three-spin NMR systems by finding sub-Riemannian geodesics on a quotient space of SU(4). This paper outlines a method for extending their results via the Griffiths formalism for constrained variational problems.

Moseley, Christopher G.

2004-08-01

138

Single Transverse-Spin Asymmetries at Large-x  

SciTech Connect

The large-x behavior of the transverse-momentum dependent quark distributions is analyzed in the factorization-inspired perturbative QCD framework, particularly for the naive time-reversal-odd quark Sivers function which is responsible for the single transverse-spin asymmetries in various semi-inclusive hard processes. By examining the dominant hard gluon exchange Feynman diagrams, and using the resulting power counting rule, we find that the Sivers function has power behavior (1-x){sup 4} at x {yields} 1, which is one power of (1-x) suppressed relative to the unpolarized quark distribution. These power-counting results provide important guidelines for the parameterization of quark distributions and quark-gluon correlations.

Brodsky, Stanley J.; Yuan, Feng

2006-10-24

139

Global fitting of single spin asymmetry: an attempt  

SciTech Connect

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

Alexey Prokudin,Zhong-Bo Kang

2012-04-01

140

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

141

Model for the coherent optical manipulation of a single spin state in a charged quantum dot  

Microsoft Academic Search

The optically driven coherent dynamics associated with the single-shot initialization and readout of a localized spin in a charged semiconductor quantum dot embedded in a realistic structure is theoretically studied using a new Maxwell-pseudospin model. Generalized pseudospin master equation is derived for description of the time evolution of spin coherences and spin populations in terms of the real state pseudospin

G. Slavcheva

2008-01-01

142

Single-particle spin effect on fission fragment angular momentum  

NASA Astrophysics Data System (ADS)

Independent isomeric yield ratios (IYR) of 128Sb, 130Sb, 132Sb, 131Te, 133Te, 132I, 134I, 136I, 135Xe, and 138Cs have been determined in the fast neutron-induced fission of 243Am using the radiochemical and ?-ray spectrometric technique. From the IYR, fragment angular momenta (J rms) have been deduced using the spin-dependent statistical model analysis. From the J rms-values and experimental kinetic energy data deformation parameters (?) have been deduced using the pre-scission bending mode oscillation model and the statistical model. The J rms- and ?-values of fission fragments from the present and earlier work in the odd-Z fissioning systems ( 238Np * , 242Am * and 244Am * ) are compared with the literature data in the even-Z fissioning systems ( 230, 233Th * , 233, 234, 236, 239U * , 239, 240, 241, 242Pu * , 244Cm(SF), 245, 246Cm * , 250Cf * and 252Cf(SF)) to examine the role of single-particle (proton) spin effect. It was observed that i) in all the fissioning systems J rms- and ?-values of the fragments with spherical 82n shell and even-Z products are lower than the fragments away from the spherical neutron shell and odd-Z products, which indicate the effect of nuclear structure. ii) For both even-Z and odd-Z fission products J rms-values increase with Z F 2/A F due to increase in Coulomb torque. iii) The J rms- and ?-values of even-Z fission products are comparable in all the fissioning systems. However, for odd-Z fission products they are slightly higher in the odd-Z fissioning systems compared to their adjacent even-Z fissioning systems. This is possible due to the contribution of the extra single-particle (proton) spin of the odd-Z fissioning systems to their odd-Z fragments. iv) The yield-weighted fragment angular momentum and elemental yields profile shows an anti-correlation in even-Z fissioning systems but not in the odd-Z fissioning systems.

Naik, H.; Dange, S. P.; Singh, R. J.; Reddy, A. V. R.

2007-02-01

143

Generation and manipulation of spin current via a hybrid four-terminal single-molecule junction  

NASA Astrophysics Data System (ADS)

We present a new device which consists of a molecular quantum dot (MQD) attached to a normal-metal, two ferromagnetic (FM), and a superconducting leads. The spin-related Andreev reflection (AR) current and the spin-dependent single-particle tunneling current through the normal-metal terminal are obtained, and it is found that the spin current exhibits the transistor-like behavior. The joint effects of the coherent spin flip and the angle between magnetic moments of the two FM leads on the spin current are also studied, these results provide the possibility to manipulate the spin current with the system parameters.

Zhang, Rong; Bai, Long; Duan, Chen-Long

2012-07-01

144

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

145

Single Spin Asymmetries in Elastic Electron-Nucleon Scattering.  

National Technical Information Service (NTIS)

We discuss the target and beam normal spin asymmetries in elastic electron-nucleon scattering which depend on the imaginary part of two-photon exchange processes between electron and nucleon. In particular, we estimate these transverse spin asymmetries fo...

B. Pasquini

2004-01-01

146

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

147

Controlling spins in adsorbed molecules by a chemical switch  

Microsoft Academic Search

The development of chemical systems with switchable molecular spins could lead to the architecture of materials with controllable magnetic or spintronic properties. Here, we present conclusive evidence that the spin of an organometallic molecule coupled to a ferromagnetic substrate can be switched between magnetic off and on states by a chemical stimulus. This is achieved by nitric oxide (NO) functioning

Christian Wäckerlin; Dorota Chylarecka; Armin Kleibert; Kathrin Müller; Cristian Iacovita; Frithjof Nolting; Thomas A. Jung; Nirmalya Ballav

2010-01-01

148

Spontaneous emission and optical control of spins in quantum dots  

Microsoft Academic Search

Quantum dots are attractive due to their potential technological applications and the opportunity they provide for study of fundamental physics in the mesoscopic scale. This dissertation studies optically controlled spins in quantum dots in connection to quantum information processing. The physical realization of the quantum bit (qubit) consists of the two spin states of an extra electron confined in a

Sophia E. Economou

2006-01-01

149

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

150

A Super Job of Spin Control  

NSF Publications Database

... will cause a given flux tube to move to one side (with the patch of spins underneath moving along ... direction will move it back to the other side (see animation at right). Although Janko and his ...

151

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

152

Controlling spins in adsorbed molecules by a chemical switch  

PubMed Central

The development of chemical systems with switchable molecular spins could lead to the architecture of materials with controllable magnetic or spintronic properties. Here, we present conclusive evidence that the spin of an organometallic molecule coupled to a ferromagnetic substrate can be switched between magnetic off and on states by a chemical stimulus. This is achieved by nitric oxide (NO) functioning as an axial ligand of cobalt(II)tetraphenylporphyrin (CoTPP) ferromagnetically coupled to nickel thin-film (Ni(001)). On NO addition, the coordination sphere of Co2+ is modified and a NO–CoTPP nitrosyl complex is formed, which corresponds to an off state of the Co spin. Thermal dissociation of NO from the nitrosyl complex restores the on state of the Co spin. The NO-induced reversible off–on switching of surface-adsorbed molecular spins observed here is attributed to a spin trans effect.

Wackerlin, Christian; Chylarecka, Dorota; Kleibert, Armin; Muller, Kathrin; Iacovita, Cristian; Nolting, Frithjof; Jung, Thomas A.; Ballav, Nirmalya

2010-01-01

153

Controlling spins in adsorbed molecules by a chemical switch.  

PubMed

The development of chemical systems with switchable molecular spins could lead to the architecture of materials with controllable magnetic or spintronic properties. Here, we present conclusive evidence that the spin of an organometallic molecule coupled to a ferromagnetic substrate can be switched between magnetic off and on states by a chemical stimulus. This is achieved by nitric oxide (NO) functioning as an axial ligand of cobalt(II)tetraphenylporphyrin (CoTPP) ferromagnetically coupled to nickel thin-film (Ni(001)). On NO addition, the coordination sphere of Co(2+) is modified and a NO-CoTPP nitrosyl complex is formed, which corresponds to an off state of the Co spin. Thermal dissociation of NO from the nitrosyl complex restores the on state of the Co spin. The NO-induced reversible off-on switching of surface-adsorbed molecular spins observed here is attributed to a spin trans effect. PMID:20975713

Wäckerlin, Christian; Chylarecka, Dorota; Kleibert, Armin; Müller, Kathrin; Iacovita, Cristian; Nolting, Frithjof; Jung, Thomas A; Ballav, Nirmalya

2010-01-01

154

Suspended Nanowires as Mechanically Controlled Rashba Spin Splitters  

NASA Astrophysics Data System (ADS)

Suspended nanowires are shown to provide mechanically controlled coherent mixing or splitting of the spin states of transmitted electrons, caused by the Rashba spin-orbit interaction. The sensitivity of the latter to mechanical bending makes the wire a tunable nanoelectromechanical weak link between reservoirs. When the reservoirs are populated with misbalanced “spin-up and spin-down” electrons, the wire becomes a source of split spin currents, which are not associated with electric charge transfer and which do not depend on temperature or driving voltages. The mechanical vibrations of the bended wires allow for additional tunability of these splitters by applying a magnetic field and varying the temperature. Clean metallic carbon nanotubes of a few microns length are good candidates for generating spin conductance of the same order as the charge conductance (divided by e2) which would have been induced by electric driving voltages.

Shekhter, R. I.; Entin-Wohlman, O.; Aharony, A.

2013-10-01

155

Active control of magnetoresistance of organic spin valves using ferroelectricity.  

PubMed

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

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

2014-01-01

156

Active control of magnetoresistance of organic spin valves using ferroelectricity  

PubMed Central

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

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

2014-01-01

157

Externally controlled spin state switching in metal-organic complexes.  

NASA Astrophysics Data System (ADS)

Recent transport experiments have demonstrated that a manipulation of the charge of individual molecules is feasible using electromigrated metal junctions [1] or electrochemical gates in conjunction with the STM [2]. Using elaborated density functional theory calculations, we will discuss a possibility to induce -- by means of charging or applied stress -- a switching between low and high spin states in certain metal-organic systems, [Fe(bpp)2]^2+ (bpp: bispyrazolyl pyridine) and [Mn(tpy)2]^2+ (tpy: terpyridine). Based upon a recent success of the single molecular conduction experiment through Ru(II) complex [3], we anticipate the transport properties of Fe(II) and Mn(II) complexes to be gate controlled via exploiting their spin degree of freedom. [1] E. A. Osorio et al., J. Phys.: Condens. Matter20, 374121 (2008); [2] F. Chen el al., Ann. Rev. Phys. Chem. 58, 535 (2007); Li et al., Nanotechnology 18, 044018 (2007). [3] M. Ruben, A. Landa, E. L"ortscher, H. Riel, M. Mayor, H. G"orls, H. Weber, A. Arnold, and F. Evers, Small (online), DOI: 10.1002/smll.200800390 (2008).

Bagrets, Alexei; Meded, Velimir; Ruben, Mario; Evers, Ferdinand

2009-03-01

158

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

159

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

PubMed Central

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

2014-01-01

160

Polytype control of spin qubits in silicon carbide  

NASA Astrophysics Data System (ADS)

The search for coherently addressable spin states in technologically important materials is a promising direction for solid-state quantum information science. Silicon carbide, a particularly suitable target, is not a single material but a collection of about 250 known polytypes, each with its own set of physical properties and technological applications. We show that in spite of these differences, the 4H-, 6H-, and 3C-SiC polytypes all exhibit optically addressable spins with long coherence times [1]. These results include room temperature spins in all three polytypes and suggest a new method for tuning quantum states using crystal polymorphism. 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. Since such inequivalent spin have distinct optical and spin transition energies, these interactions could lead to dipole-coupled networks of separately addressable spins.[4pt] [1] A. Falk et al., submitted

Falk, A. L.; Buckley, B. B.; Calusine, G.; Koehl, W. F.; Politi, A.; Awschalom, D. D.; Dobrovitski, V. V.; Zorman, C. A.; Feng, P. X.-L.

2013-03-01

161

Optimized dynamical control of state transfer through noisy spin chains  

NASA Astrophysics Data System (ADS)

We propose a method of optimally controlling the tradeoff of speed and fidelity of state transfer through a noisy quantum channel (spin-chain). This process is treated as qubit state-transfer through a fermionic bath. We show that dynamical modulation of the boundary-qubits levels can ensure state transfer with the best tradeoff of speed and fidelity. This is achievable by dynamically optimizing the transmission spectrum of the channel. The resulting optimal control is robust against both static and fluctuating noise in the channel?s spin–spin couplings. It may also facilitate transfer in the presence of diagonal disorder (on site energy noise) in the channel.

Zwick, Analia; Álvarez, Gonzalo A.; Bensky, Guy; Kurizki, Gershon

2014-06-01

162

Mechanism for electric field driven single spin manipulation of a Mn dopant in GaAs  

Microsoft Academic Search

We show that the spin orientation of a J=1 (Mn + hole) complex in GaAs can be manipulated using only electrical control fields. The spin degeneracy of the compound spin can be split by a dc electric field due to inversion symmetry breaking. The resonances, corresponding to transitions between the split levels, can be driven by an ac electric field.

Jian-Ming Tang; Jeremy Levy; Michael E. Flatté

2005-01-01

163

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

164

Periodic attitude control of a slowly spinning spacecraft.  

NASA Technical Reports Server (NTRS)

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

Todosiev, E. P.

1973-01-01

165

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.

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

2012-01-01

166

Nonequilibrium intrinsic spin torque in a single nanomagnet  

Microsoft Academic Search

The spin transfer torque usually observed in metallic and tunneling spin-valves, as well as magnetic domain walls, comes from the transfer of the transverse spin-current of conduction electrons to the magnetization [1]. Therefore, it requires both a non collinear configuration of the magnetic structure (or inhomogeneous magnetic texture in the case of domain walls) and magneto-resistive effects. However, a number

Aurelien Manchon

2009-01-01

167

Experimental Study of Single Spin Asymmetries and TMDs  

NASA Astrophysics Data System (ADS)

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

Chen, Jian-Ping

2014-01-01

168

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

169

Spinoptical metamaterials: spin-controlled photonics based on symmetry violation  

NASA Astrophysics Data System (ADS)

Spinoptics provides a route to control light, whereby the photon helicity (spin angular momentum) degeneracy is removed due to a geometric gradient onto a metasurface. The alliance of spinoptics and metamaterials offers the dispersion engineering of a structured matter in a polarization helicity dependent manner. We show that polarization-controlled optical modes of metamaterials arise where the spatial inversion symmetry is violated. The emerged spin-split dispersion of spontaneous emission originates from the spin-orbit interaction of light, generating a selection rule based on symmetry restrictions in a spinoptical metamaterial. The inversion asymmetric metasurface is obtained via anisotropic optical antenna patterns. This type of metamaterial provides a route for spin-controlled nanophotonic applications based on the design of the metasurface symmetry properties.

Shitrit, Nir; Yulevich, Igor; Maguid, Elhanan; Ozeri, Dror; Veksler, Dekel; Kleiner, Vladimir; Hasman, Erez

2013-09-01

170

Coherent Control of Collective Atomic Spins  

NASA Astrophysics Data System (ADS)

In this thesis I explore the use of collective spin angular momentum as a platform for quantum information processing. In the limit of a large number of atoms, the collective variables of atomic systems have a natural connection to the bosonic algebra of light (known as the Holstein-Primakoff or HP approximation) where components of the collective spin angular momentum effectively act as quadratures, making them natural systems for coupling to light. I have sought to improve previous schemes for the spin squeezing of atomic ensembles, such as the proposal of Takeuchi et. al. based on coherent quantum feedback [39]. In this scheme a beam of linearly polarized light passes through the atomic ensemble (prepared in a coherent state), coupling to the atoms through a state-dependent index of refraction (the Faraday effect). The light is then passed through a wave-plate and reflected back through the atoms for a second pass. This double-pass scheme leads to an effective nonlinearity as the atomic fluctuations are mapped onto the light on the first pass and then back on to the atoms in the second pass. The light acts as a bus coupling each atom to each of the others. This nonlinear interaction forms a shearing of the atomic coherent state that results in squeezing. The light is entangled to the atoms through these interactions, and remains entangled as it escapes the system. This leads to decoherence of the atoms as the light is lost to the environment, reducing the amount of spin squeezing achieved. The first step towards improving the double-pass scheme was to add a quantum eraser step in which the light is disentangled from the squeezed atoms. By first measuring one quadrature of the light, and then performing a measurement-dependent rotation on the atomic ensemble, it is possible to decouple the atoms and light so that the loss of the light does not reduce the atomic squeezing. This results in an improvement of the rate of atomic spin squeezing. A complete model includes the effects of photon-atom scattering and other noise and loss effects on the overall rate of squeezing. Previous derivations of noise due to photon-atom scattering have started with the unjustified assumptions that the atomic and photonic decoherence channels were both Gaussian and independent of correlations between the two subsystems. They then proceed with very general statistical arguments that rely upon these simplifications. My work begins with the more fundamental master equation picture in which I find the Linblad jump operators. I find that in general the photonic and atomic loss channels are not independent, with the intensity of the light dictating the details of this dependence, and find the conditions under which the Gaussian approximation holds. Squeezing and loss is initially treated assuming ensembles of spin-1/2 atoms, but this work is further extended to higher dimensional subsystems. For a higher spin case, preparing the atoms in spin coherent states is not optimal. One can engineer a stronger interaction by preparing the atoms in an atomic "cat state", i.e., a superposition of the two stretch states along the direction of propagation of the light beam. The fluctuations of such a state are more strongly coupled to the light, resulting in a stronger nonlinearity. This leads to strong correlations between the atoms, but they are not immediately useful for squeezing; the cat state must be coherently mapped to a coherent state to achieve atomic spin squeezing. The state created in this manner is ultimately more squeezed than that achieved with the same interaction but prepared initially in a coherent state. (Abstract shortened by UMI.)

Trail, Collin M.

171

Progress towards single spin optoelectronics using quantum dot nanostructures  

Microsoft Academic Search

We summarise recent progress in our understanding of the physics of fundamental charge and spin excitations in quantum dot semiconductor nanostructures. Many novel potential applications of these nanostructures have arisen from the strong optical non-linearities that exist in the few-particle quantum dot absorption spectrum. By comparison, the interaction of the electron spin with other localised charges in the dot and

Domink Heiss; Miro Kroutvar; Jonathan J. Finley; Gerhard Abstreiter

2005-01-01

172

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

Microsoft Academic Search

Manipulation of the spin states of a quantum dot by purely electrical means is a highly desirable property of fundamental importance for the development of spintronic devices such as spin filters, spin transistors and single spin memories as well as for solid-state qubits. An electrically gated quantum dot in the Coulomb blockade regime can be tuned to hold a single

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

2008-01-01

173

Sensitive magnetic control of ensemble nuclear spin hyperpolarization in diamond  

NASA Astrophysics Data System (ADS)

Dynamic nuclear polarization, which transfers the spin polarization of electrons to nuclei, is routinely applied to enhance the sensitivity of nuclear magnetic resonance. This method is particularly useful when spin hyperpolarization can be produced and controlled optically or electrically. Here we show complete polarization of nuclei located near optically polarized nitrogen-vacancy centres in diamond. Close to the ground-state level anti-crossing condition of the nitrogen-vacancy electron spins, 13C nuclei in the first shell are polarized in a pattern that depends sensitively upon the magnetic field. Based on the anisotropy of the hyperfine coupling and of the optical polarization mechanism, we predict and observe a reversal of the nuclear spin polarization with only a few millitesla change in the magnetic field. This method of magnetic control of high nuclear polarization at room temperature can be applied in sensitivity enhanced nuclear magnetic resonance of bulk nuclei, nuclear-based spintronics, and quantum computation in diamond.

Wang, Hai-Jing; Shin, Chang S.; Avalos, Claudia E.; Seltzer, Scott J.; Budker, Dmitry; Pines, Alexander; Bajaj, Vikram S.

2013-06-01

174

Production of spin-controlled rare isotope beams  

NASA Astrophysics Data System (ADS)

The degree of freedom of spin in quantum systems serves as an unparalleled laboratory where intriguing quantum physical properties can be observed, and the ability to control spin is a powerful tool in physics research. We propose a method for controlling spin in a system of rare isotopes which takes advantage of the mechanism of the projectile fragmentation reaction combined with the momentum-dispersion matching technique. The present method was verified in an experiment at the RIKEN RI Beam Factory, in which a degree of alignment of 8% was achieved for the spin of a rare isotope 32Al. The figure of merit for the present method was found to be greater than that of the conventional method by a factor of more than 50.

Ichikawa, Yuichi; Ueno, Hideki; Ishii, Yuji; Furukawa, Takeshi; Yoshimi, Akihiro; Kameda, Daisuke; Watanabe, Hiroshi; Aoi, Nori; Asahi, Koichiro; Balabanski, Dimiter L.; Chevrier, Raphaël; Daugas, Jean-Michel; Fukuda, Naoki; Georgiev, Georgi; Hayashi, Hironori; Iijima, Hiroaki; Inabe, Naoto; Inoue, Takeshi; Ishihara, Masayasu; Kubo, Toshiyuki; Nanao, Tsubasa; Ohnishi, Tetsuya; Suzuki, Kunifumi; Tsuchiya, Masato; Takeda, Hiroyuki; Rajabali, Mustafa M.

2012-12-01

175

Spin-polarized transport through single-molecule magnet Mn6 complexes.  

PubMed

The coherent transport properties of a device, constructed by sandwiching a Mn6 single-molecule magnet between two gold surfaces, are studied theoretically by using the non-equilibrium Green's function approach combined with density functional theory. Two spin states of such Mn6 complexes are explored, namely the ferromagnetically coupled configuration of the six Mn(III) cations, leading to the S = 12 ground state, and the low S = 4 spin state. For voltages up to 1 volt the S = 12 ground state shows a current one order of magnitude larger than that of the S = 4 state. Furthermore this is almost completely spin-polarized, since the Mn6 frontier molecular orbitals for S = 12 belong to the same spin manifold. As such the high-anisotropy Mn6 molecule appears as a promising candidate for implementing, at the single molecular level, both spin-switches and low-temperature spin-valves. PMID:23599124

Cremades, Eduard; Pemmaraju, C D; Sanvito, Stefano; Ruiz, Eliseo

2013-06-01

176

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

NASA Astrophysics Data System (ADS)

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

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

2000-08-01

177

Controllable spin-dependent transport in armchair graphene nanoribbon structures  

Microsoft Academic Search

Using the non-equilibrium Green's functions formalism in a tight binding\\u000amodel, the spin-dependent transport in armchair graphene nanoribbon (GNR)\\u000astructures controlled by a ferromagnetic gate is investigated. Beyond the\\u000aoscillatory behavior of conductance and spin polarization with respect to the\\u000abarrier height, which can be tuned by the gate voltage, we especially analyze\\u000athe effect of width-dependent band gap and

V. Hung Nguyen; V. Nam Do; A. Bournel; V. Lien Nguyen; P. Dollfus

2009-01-01

178

Quantum gates controlled by spin chain soliton excitations  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

179

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

180

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

181

Coherent Population Trapping of Single Spins in Diamond under Optical Excitation  

NASA Astrophysics Data System (ADS)

The nitrogen-vacancy (N-V) center in diamond has long-lived electronic and nuclear spin coherence combined with optical addressability, making it an attractive candidate system for building a photonic network for quantum information applications. However, realizing such schemes will require control over the N-V energy level structure and integration into high-quality microphotonic structures operating at visible wavelengths. In this talk I will describe experiments on optical manipulation of N-V centers in low-nitrogen diamond samples. Typically the optical transitions of NV^- are spin-conserving, so that if the N-V begins in the ms=0 ground state, it can undergo many optical excitation/fluorescence cycles before transitioning to ms=±1. However, by applying stress to the crystal, or by using strain already present, it is possible to realize a ?-type system with one excited state coupled by optical transitions to multiple ground states. By this technique we have observed coherent population trapping both in N-V ensembles and in single N-V centers. These results demonstrate the potential for all-optical spin manipulation in this system. I will also describe initial work on coupling N-V centers to photonic structures with the goal of enhancing emission into the zero-phonon line, as needed for applications such as quantum repeaters.

Santori, Charles

2008-03-01

182

Ultrafast Spin-Motion Entanglement and Interferometry with a Single Atom.  

National Technical Information Service (NTIS)

We report entanglement of a single atom's hyperfine spin state with its motional state on a timescale of order 15 ns. We engineer a short train of intense laser pulses to impart a spin-dependent momentum transfer of +/-2hk. We further create an atomic int...

C. Senko C. W. Conover J. Mizrahi K. G. Johnson W. C. Campbell

2012-01-01

183

Coherent control and detection of spin qubits in semiconductor with magnetic field engineering  

NASA Astrophysics Data System (ADS)

Electrical control and detection of the spin qubits in semiconductor quantum dots (QDs) are among the major rapidly progressing fields for possible implementation of scalable quantum information processing. Coherent control of one-[1-3] and two-[4,5] spin qubits by electrical means had been demonstrated with various approaches. We have used an engineered magnetic field structure realized with proximal micro-magnets to transduce the spin and charge degrees of freedom and to selectively address one of the two spins [3]. We have demonstrated an all-electrical two-qubit gate consisting of single-spin rotations and interdot spin exchange in double QDs. A partially entangled output state is obtained by the application of the two-qubit gate to an initial, uncorrelated state. Our calculations taking into account of the nuclear spin fluctuation show the degree of entanglement. Non-uniform magnetic field also enables spin selective photon-assisted tunneling in double QDs, which then constitutes non-demolition spin read-out system in combination with a near-by charge detector [6]. [4pt] In collaboration with R. Brunner, Inst. of Phys., Montanuniversitaet Leoben, 8700, Austria, M. Pioro-Ladrière, D'ep. de Phys., Universit'e de Sherbrooke, Sherbrooke, Qu'ebec, J1K-2R1, Canada, T. Kubo, Y. -S. Shin, T. Obata, and S. Tarucha, ICORP-JST and Dep. of Appl. Phys., Univ. of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.[4pt] [1] F. H. Koppens, et al., Nature 442, 766 (2006).[0pt] [2] K. C. Nowack, et al., Science 318, 1430 (2007).[0pt] [3] M. Pioro-Ladrière, et al., Nature Physics 4, 776 (2008).[0pt] [4] J. R. Petta, et al., Science 309, 2180 (2005).[0pt] [5] R. Brunner, et al., Phys. Rev. Lett. 107, 146801 (2011).[0pt] [6] Y. -S. Shin, et al., Phys. Rev. Lett. 104, 046802 (2010).

Tokura, Yasuhiro

2012-02-01

184

Design of a Digital Controller for Spinning Flexible Spacecraft.  

National Technical Information Service (NTIS)

An approach to digital control system design is applied to the analysis and design of a practical onboard digital attitude control system for a class of spinning vehicles characterized by a rigid body and two connected flexible appendages. The approach us...

B. C. Kuo S. B. Seltzer G. Singh R. A. Yackel

1974-01-01

185

Quantum control of a spin qubit coupled to a photonic crystal cavity  

NASA Astrophysics Data System (ADS)

A key ingredient for a quantum network is an interface between stationary quantum bits and photons, which act as flying qubits for interactions and communication. Photonic crystal architectures are promising platforms for enhancing the coupling of light to solid-state qubits. Quantum dots can be integrated into a photonic crystal, with optical transitions coupling to photons and spin states forming a long-lived quantum memory. Many researchers have now succeeded in coupling these emitters to photonic crystal cavities, but there have been no demonstrations of a functional spin qubit and quantum gates in this environment. Here, we have developed a coupled cavity-quantum dot system in which the dot is controllably charged with a single electron. We perform the initialization, rotation and measurement of a single electron spin qubit using laser pulses, and find that the cavity can significantly improve these processes.

Carter, Samuel G.; Sweeney, Timothy M.; Kim, Mijin; Kim, Chul Soo; Solenov, Dmitry; Economou, Sophia E.; Reinecke, Thomas L.; Yang, Lily; Bracker, Allan S.; Gammon, Daniel

2013-04-01

186

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

187

Controlling spin contamination using constrained density functional theory  

NASA Astrophysics Data System (ADS)

We have extended the constrained density functional theory (DFT) approach to explicitly control the magnitude of spin contamination. Unlike a restricted or restricted open-shell approach, the present method allows finer granularity, not only constraining the magnitude of the spin contamination but also allowing for the possibility of applying the constraint to a subsystem of a much larger system. This allows for the description of spin polarization where physically meaningful, while simultaneously enabling the reduction of spurious overpolarization that is present in many DFT functionals. We utilize this constraint in two particular model applications: The calculation of isotropic and anisotropic hyperfine couplings of a transition metal complex, [Mn(CN)5NO]2-, and the calculation of the diabatic dissociation curves of OF radical. In both cases, the spin contamination constraint is essential for obtaining physically meaningful, qualitatively correct, results.

Schmidt, J. R.; Shenvi, Neil; Tully, John C.

2008-09-01

188

Controlling and Imaging Quantum Gases at the Single Atom Level  

NASA Astrophysics Data System (ADS)

Over the past years, ultracold quantum gases in optical lattices have offered remarkable opportunities to investigate static and dynamic properties of strongly correlated bosonic or fermionic quantum many-body systems. In this talk I will show how it has recently not only become possible to image such quantum gases with single atom sensitivity and single site resolution, but also how it is now possible to coherently control single atoms on individual lattice sites within a strongly correlated quantum gas. Using a tightly focused laser beam, atoms on selected lattice sites can be addressed and their spin state fully controlled. Magnetic resonance control techniques were employed to achieve sub-lattice period and sub-diffraction limited resolution in our addressing scheme. The ability to address single atoms on a lattice opens a whole range of novel research opportunities, ranging from quantum information processing over the investigation of quantum spin systems to local entropy control, some of which will be discussed in the talk.

Bloch, Immanuel

2011-06-01

189

Controlled coupling of spin-resolved quantum Hall edge states  

NASA Astrophysics Data System (ADS)

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

Karmakar, Biswajit

2012-02-01

190

Spin-dependent quantum interference within a single Co nanostructure  

NASA Astrophysics Data System (ADS)

We present results of a combined experimental and theoretical study of spin-polarized electron confinement on individual nm small Co islands on Cu(111). Spin-polarized low-temperature STM in magnetic fields is used to identify and prepare parallel (P) and anti-parallel (AP) states of the magnetization orientation between a Co island and the magnetic tip of the STM. We find a pronounced spatial modulation of the differential conductance within one island, which is ascribed to electron confinement. The analysis of these modulation patterns for P and AP magnetization states between tip and island reveals a strong variation between both states. Maps of the asymmetry of the differential conductance, (GAP-GP)/(GAP+GP), show strong spatial variations, where the contrast depends on the gap voltage. These results are ascribed to a spatial modulation of the spin-polarization within the Co islands. In conjunction with theory we conclude that the modulation of the spin- polarization, and its variation with energy, can be described by the relative magnitudes of the spin-resolved density of states, where the spatial modulation is mainly due to electron confinement of majority electrons.

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

2010-03-01

191

Spin-orbit-induced strong coupling of a single spin to a nanomechanical resonator.  

PubMed

We theoretically investigate the deflection-induced coupling of an electron spin to vibrational motion due to spin-orbit coupling in suspended carbon nanotube quantum dots. Our estimates indicate that, with current capabilities, a quantum dot with an odd number of electrons can serve as a realization of the Jaynes-Cummings model of quantum electrodynamics in the strong-coupling regime. A quantized flexural mode of the suspended tube plays the role of the optical mode and we identify two distinct two-level subspaces, at small and large magnetic field, which can be used as qubits in this setup. The strong intrinsic spin-mechanical coupling allows for detection, as well as manipulation of the spin qubit, and may yield enhanced performance of nanotubes in sensing applications. PMID:23003173

Pályi, András; Struck, P R; Rudner, Mark; Flensberg, Karsten; Burkard, Guido

2012-05-18

192

Quantum Computation Using the 13C Nuclear Spins Near the Single NV Defect Center in Diamond  

NASA Astrophysics Data System (ADS)

We discuss the possibility of realizing quantum computation on the basis of a cluster of single interacting nuclear spins in solids. This idea seems to be feasible because of the combination of two techniques—Single Molecule Spectroscopy and Optically Detected Electron Nuclear Double Resonance. Compared to the well-known bulk Nuclear Magnetic Resonance (NMR), the proposed method of quantum computation has the advantage that quantum computation is performed with pure spin states and the quantum processor is more easily scalable. At the same time, the advantages of NMR quantum computation are kept: long coherence time and easy construction of quantum gates. As a specific system to implement the above idea, we discuss the 13C-nuclear spins in the nearest vicinity of a single nitrogen-vacancy (NV) defect center in diamond, which can be optically detected using the technique of scanning confocal microscopy. Owing to the hyperfine coupling of the ground state electron paramagnetic spin S=1 of the center to 13C nuclear spins in a diamond lattice, the states of nuclear spins in the vicinity of the defect-center can be addressed individually. Preliminary consideration shows that it should be possible to address up to 12 individual 13C nuclear spins. The dephasing time of the nuclear spin states at low temperatures allows realization up to 105 gates.

Wrachtrup, J.; Kilin, S. Ya.; Nizovtsev, A. P.

2001-09-01

193

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.

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

2013-01-01

194

Dimensional control of cobalt spin state in oxide superlattices  

NASA Astrophysics Data System (ADS)

Perovskite cobalt oxide is a very intriguing system with various spin states owing to the delicate balance between crystal field splitting and Hund exchange energy. In this talk, we show that its spin state can be altered through dimensional control, enabled by digital synthesis of perovskite cobalt oxide superlattices. We employed a few unit cells of LaCoO3 as an active magnetic layer, separated by LaAlO3 spacer layer. High quality [(LaCoO3)n(LaAlO3)n]8 (n = 2, 6, and 10) superlattices were fabricated using pulsed laser epitaxy. Spectroscopic tools including x-ray absorption spectroscopy and optical spectroscopy revealed clear evolution of the electronic structure and resultant spin state by changing dimensionality. Specifically, the spin state changed from a high to a low spin state with a larger optical band gap, as the dimension reduced from 3D to 2D. Dynamic mean field calculation supported the critical role of dimensionality on the spin state and electronic structure of LaCoO3.

Jeong, Da Woon; Choi, W. S.; Okamoto, S.; Sohn, C. H.; Park, H. J.; Kim, J.-Y.; Lee, H. N.; Kim, K. W.; Moon, S. J.; Noh, T. W.

2013-03-01

195

Nanoscale broadband transmission lines for spin qubit control.  

PubMed

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. PMID:23221273

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

2013-01-11

196

Control of open quantum systems: case study of the central spin model  

NASA Astrophysics Data System (ADS)

We study the controllability of a central spin guided by a classical field and interacting with a spin bath and show that the central spin is fully controllable independently of the number of bath spins. Additionally we find that for unequal system-bath couplings even the bath becomes controllable by acting on the central spin alone. We then analyze numerically how the time to implement gates on the central spin scales with the number of bath spins and conjecture that for equal system-bath couplings it reaches a saturation value. We provide evidence that sometimes noise can be effectively suppressed through control.

Arenz, Christian; Gualdi, Giulia; Burgarth, Daniel

2014-06-01

197

Design of a digital controller for spinning flexible spacecraft.  

NASA Technical Reports Server (NTRS)

A new approach to digital control system design is applied to the analysis and design of a practical onboard digital attitude control system for a class of spinning vehicles characterized by a rigid body and two connected flexible appendages. The approach used is to design a continuous-data control system that will provide a satisfactory system response. Then, using the digital redesign method, a digital controller with onboard digital computer is designed to provide a digital control system whose states are similar to those of the continuous system at sampling instants. The simplicity of application of this approach is indicated by an example in which spinning Skylab parameters are used to substantiate the conclusions.

Kuo, B. C.; Singh, G.; Yackel, R. A.; Seltzer, S. M.

1973-01-01

198

Design of a digital controller for spinning flexible spacecraft  

NASA Technical Reports Server (NTRS)

An approach to digital control system design is applied to the analysis and design of a practical onboard digital attitude control system for a class of spinning vehicles characterized by a rigid body and two connected flexible appendages. The approach used is to design a continuous-data control system that will provide a satisfactory system response. Then, using the digital redesign method, a digital controller with onboard digital computer is designed to provide a digital control system whose states are similar to those of the continuous system at sampling instants. The simplicity of application of this approach is indicated by example. The example, using spinning Skylab parameters, is used to substantiate the conclusions.

Kuo, B. C.; Seltzer, S. B.; Singh, G.; Yackel, R. A.

1974-01-01

199

A brushless dc spin motor for momentum exchange altitude control  

NASA Technical Reports Server (NTRS)

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

Stern, D.; Rosenlieb, J. W.

1972-01-01

200

Formal Analysis of a SpaceCraft Controller Using SPIN  

Microsoft Academic Search

This paper documents an application of the finite state model checker SPIN to formally analyze a multi-threaded plan execution module. The plan execution module is one component of NASA's New Millennium Remote Agent, an artificial intelligence based spacecraft control system ar- chitecture which launched in October of 1998 as part of the DEEP SPACE 1 mission. The bottom layer of

Klaus Havelund; Michael R. Lowry; John Penix

2001-01-01

201

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

202

A light-induced spin crossover actuated single-chain magnet  

NASA Astrophysics Data System (ADS)

Both spin-crossover complexes and molecular nanomagnets display bistable magnetic states, potentially behaving as elementary binary units for information storage. It is a challenge to introduce spin-crossover units into molecular nanomagnets to switch the bistable state of the nanomagnets through external stimuli-tuned spin crossover. Here we report an iron(II) spin-crossover unit and paramagnetic iron(III) ions that are incorporated into a well-isolated double-zigzag chain. The chain exhibits thermally induced reversible spin-crossover and light-induced excited spin-state trapping at the iron(II) sites. Single-chain magnet behaviour is actuated accompanying the synergy between light-induced excited spin-state trapping at the iron(II) sites and ferromagnetic interactions between the photoinduced high-spin iron(II) and low-spin iron(III) ions in the chain. The result provides a strategy to switch the bistable state of molecular nanomagnets using external stimuli such as light and heat, with the potential to erase and write information at a molecular level.

Liu, Tao; Zheng, Hui; Kang, Soonchul; Shiota, Yoshihito; Hayami, Shinya; Mito, Masaki; Sato, Osamu; Yoshizawa, Kazunari; Kanegawa, Shinji; Duan, Chunying

2013-11-01

203

Single-laser-shot-induced complete bidirectional spin transition at room temperature in single crystals of (FeII(pyrazine)(Pt(CN)4)).  

PubMed

Single crystals of the {Fe (II)(pyrazine)[Pt(CN) 4]} spin crossover complex were synthesized by a slow diffusion method. The crystals exhibit a thermal spin transition around room temperature (298 K), which is accompanied by a 14 K wide hysteresis loop. X-ray single-crystal analysis confirms that this compound crystallizes in the tetragonal P4/ mmm space group in both spin states. Within the thermal hysteresis region a complete bidirectional photoconversion was induced between the two phases (high spin right arrow over left arrow low spin) when a short single laser pulse (4 ns, 532 nm) was shined on the sample. PMID:18570417

Cobo, Saioa; Ostrovskii, Denis; Bonhommeau, Sébastien; Vendier, Laure; Molnár, Gábor; Salmon, Lionel; Tanaka, Koichiro; Bousseksou, Azzedine

2008-07-16

204

Local Spin Anisotropy Effects upon the Magnetization of Dimer Single Molecule Magnets  

NASA Astrophysics Data System (ADS)

We present an exactly soluble model of equal spin s1 dimer single molecule magnets. The dimer spins interact via the Heisenberg, Zeeman, and the most general quadratic local and global anisotropic exchange interactions. We derive the Hamiltonian matrix for the general case with each type of anisotropy. For antiferromagnetic couplings and s1 > 1/2, the low temperature T magnetization exhibits a strong influence of single-ion anisotropy. Our results suggest a substantial presence of axial single-ion anisotropy in the s1 = 5/2 Fe2 dimer, [Fe(salen)Cl]2.

Klemm, Richard A.; Efremov, Dmitri V.

2006-09-01

205

Spin coherence during optical excitation of a single nitrogen-vacancy center in diamond.  

PubMed

We examine the quantum spin state of a single nitrogen-vacancy (NV) center in diamond at room temperature as it makes a transition from the orbital ground state (GS) to the orbital excited state (ES) during nonresonant optical excitation. While the fluorescence readout of NV-center spins relies on conservation of the longitudinal spin projection during optical excitation, the question of quantum phase preservation has not been examined. Using Ramsey measurements and quantum process tomography of the optical excitation process, we measure a trace fidelity of F=0.87±0.03, which includes ES spin dephasing during measurement. Extrapolation to the moment of optical excitation yields F?0.95. This result provides insight into the interaction between spin coherence and nonresonant optical absorption through a vibronic sideband. PMID:22587283

Fuchs, G D; Falk, A L; Dobrovitski, V V; Awschalom, D D

2012-04-13

206

Spin- and energy-dependent tunneling through a single molecule with intramolecular spatial resolution.  

PubMed

We investigate the spin- and energy-dependent tunneling through a single organic molecule (CoPc) adsorbed on a ferromagnetic Fe thin film, spatially resolved by low-temperature spin-polarized scanning tunneling microscopy. Interestingly, the metal ion as well as the organic ligand show a significant spin dependence of tunneling current flow. State-of-the-art ab initio calculations including also van der Waals interactions reveal a strong hybridization of molecular orbitals and substrate 3d states. The molecule is anionic due to a transfer of one electron, resulting in a nonmagnetic (S=0) state. Nevertheless, tunneling through the molecule exhibits a pronounced spin dependence due to spin-split molecule-surface hybrid states. PMID:20867880

Brede, Jens; Atodiresei, Nicolae; Kuck, Stefan; Lazi?, Predrag; Caciuc, Vasile; Morikawa, Yoshitada; Hoffmann, Germar; Blügel, Stefan; Wiesendanger, Roland

2010-07-23

207

Optical superradiance from nuclear spin environment of single-photon emitters.  

PubMed

We show that superradiant optical emission can be observed from the polarized nuclear spin ensemble surrounding a single-photon emitter such as a single quantum dot or nitrogen-vacancy center. The superradiant light is emitted under optical pumping conditions and would be observable with realistic experimental parameters. PMID:20481939

Kessler, E M; Yelin, S; Lukin, M D; Cirac, J I; Giedke, G

2010-04-01

208

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

209

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

SciTech Connect

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

Jiang, Xiaodong [Los Alamos National Lab

2013-08-01

210

Coherent sensing of a mechanical resonator with a single-spin qubit.  

PubMed

Mechanical systems can be influenced by a wide variety of small forces, ranging from gravitational to optical, electrical, and magnetic. When mechanical resonators are scaled down to nanometer-scale dimensions, these forces can be harnessed to enable coupling to individual quantum systems. We demonstrate that the coherent evolution of a single electronic spin associated with a nitrogen vacancy center in diamond can be coupled to the motion of a magnetized mechanical resonator. Coherent manipulation of the spin is used to sense driven and Brownian motion of the resonator under ambient conditions with a precision below 6 picometers. With future improvements, this technique could be used to detect mechanical zero-point fluctuations, realize strong spin-phonon coupling at a single quantum level, and implement quantum spin transducers. PMID:22362881

Kolkowitz, Shimon; Jayich, Ania C Bleszynski; Unterreithmeier, Quirin P; Bennett, Steven D; Rabl, Peter; Harris, J G E; Lukin, Mikhail D

2012-03-30

211

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

212

Measurements of Kondo and Spin Splitting in Single-Electron Transistors  

Microsoft Academic Search

We measure the spin splitting in a magnetic field B of localized states in single-electron transistors using a new method, inelastic spin-flip cotunneling. Because it involves only internal excitations, this technique gives the most precise value of the Zeeman energy Delta=|g|muBB. In the same devices we also measure the splitting with B of the Kondo peak in differential conductance. The

A. Kogan; S. Amasha; D. Goldhaber-Gordon; G. Granger; M. A. Kastner; Hadas Shtrikman

2004-01-01

213

Efficient Organometallic Spin Filter between Single-Wall Carbon Nanotube or Graphene Electrodes  

Microsoft Academic Search

We present a theoretical study of spin transport in a class of molecular systems consisting of an organometallic benzene-vanadium cluster placed in between graphene or single-wall carbon-nanotube-model contacts. Ab initio modeling is performed by combining spin density functional theory and nonequilibrium Green's function techniques. We consider weak and strong cluster-contact bonds. Depending on the bonding we find from 73% (strong

Mohammad Koleini; Magnus Paulsson; Mads Brandbyge

2007-01-01

214

Spin-polarized transport through single-molecule magnet Mn6 complexes  

NASA Astrophysics Data System (ADS)

The coherent transport properties of a device, constructed by sandwiching a Mn6 single-molecule magnet between two gold surfaces, are studied theoretically by using the non-equilibrium Green's function approach combined with density functional theory. Two spin states of such Mn6 complexes are explored, namely the ferromagnetically coupled configuration of the six MnIII cations, leading to the S = 12 ground state, and the low S = 4 spin state. For voltages up to 1 volt the S = 12 ground state shows a current one order of magnitude larger than that of the S = 4 state. Furthermore this is almost completely spin-polarized, since the Mn6 frontier molecular orbitals for S = 12 belong to the same spin manifold. As such the high-anisotropy Mn6 molecule appears as a promising candidate for implementing, at the single molecular level, both spin-switches and low-temperature spin-valves.The coherent transport properties of a device, constructed by sandwiching a Mn6 single-molecule magnet between two gold surfaces, are studied theoretically by using the non-equilibrium Green's function approach combined with density functional theory. Two spin states of such Mn6 complexes are explored, namely the ferromagnetically coupled configuration of the six MnIII cations, leading to the S = 12 ground state, and the low S = 4 spin state. For voltages up to 1 volt the S = 12 ground state shows a current one order of magnitude larger than that of the S = 4 state. Furthermore this is almost completely spin-polarized, since the Mn6 frontier molecular orbitals for S = 12 belong to the same spin manifold. As such the high-anisotropy Mn6 molecule appears as a promising candidate for implementing, at the single molecular level, both spin-switches and low-temperature spin-valves. Electronic supplementary information (ESI) available: Calculated total and projected density of states of an isolated [Mn6O2(Et-sao)6{O2CPh(Me)2}2(EtOH)6] original SMM complex (Fig. S1). Calculated total and projected density of states of an isolated [Mn6O2(Me-sao)6{O2CPh(SH)}2(MeOH)6] model complex (Fig. S2). Transmission spectra calculated at different voltages corresponding to the S = 12 and S = 4 ground states for the Mn6-Au(111) layer system (Fig. S3). Cell parameters and Cartesian coordinates of the Mn6-Au(111) layer system. See DOI: 10.1039/c3nr00054k

Cremades, Eduard; Pemmaraju, C. D.; Sanvito, Stefano; Ruiz, Eliseo

2013-05-01

215

Magnetic field induced discontinuous spin reorientation in ErFeO3 single crystal  

NASA Astrophysics Data System (ADS)

The spin reorientation of ErFeO3 that spontaneously occurs at low temperature has been previously determined to be a process involving the continuous rotation of Fe3+ spins. In this work, the dynamic process of spin reorientation in ErFeO3 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; Cheng, Zhenxiang; Hong, Fang; Xu, Jiayue; Yuan, Shujuan; Cao, Shixun; Wang, Xiaolin

2013-11-01

216

Spin-wave instability threshold in single-crystal yttrium iron garnet for oblique pumping  

SciTech Connect

The spin-wave instability threshold h/sub crit/ for oblique pumping in high-quality single-crystal yttrium iron garnet (YIG) at room temperature and 9.317 GHz, has been examined. The experimental dependence of h/sub crit/ on the pump angle indicates that the microwave field components parallel and perpendicular to the dc field operate independently in exciting spin-wave instability. Theoretical fits to the data, based on this result, indicate that the spin-wave linewidth is strongly wave vector dependent and that the wave vector dependence varies with the pump angle.

Liu, Y.H.; Patton, C.E.

1982-07-01

217

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

PubMed

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

218

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

219

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.

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

2013-01-01

220

Oscillatory spin-polarized tunnelling from silicon quantum wells controlled by electric field  

NASA Astrophysics Data System (ADS)

Spin-dependent electronic transport is widely used to probe and manipulate magnetic materials and develop spin-based devices. Spin-polarized tunnelling, successful in ferromagnetic metal junctions, was recently used to inject and detect electron spins in organics and bulk GaAs or Si. Electric field control of spin precession was studied in III-V semiconductors relying on spin-orbit interaction, which makes this approach inefficient for Si, the mainstream semiconductor. Methods to control spin other than through precession are thus desired. Here we demonstrate electrostatic modification of the magnitude of spin polarization in a silicon quantum well, and detection thereof by means of tunnelling to a ferromagnet, producing prominent oscillations of tunnel magnetoresistance of up to 8%. The electric modification of the spin polarization relies on discrete states in the Si with a Zeeman spin splitting, an approach that is also applicable to organic, carbon-based and other materials with weak spin-orbit interaction.

Jansen, Ron; Min, Byoung-Chul; Dash, Saroj P.

2010-02-01

221

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

222

Coherent control to prepare an InAs quantum dot for spin-photon entanglement.  

PubMed

We optically generated an electronic state in a single InAs/GaAs self-assembled quantum dot that is a precursor to the deterministic entanglement of the spin of the electron with an emitted photon in the proposal of W. Yao, R.-B. Liu, and L.?J. Sham [Phys. Rev. Lett. 95, 030504 (2005). A superposition state is prepared by optical pumping to a pure state followed by an initial pulse. By modulating the subsequent pulse arrival times and precisely controlling them using interferometric measurement of path length differences, we are able to implement a coherent control technique to selectively drive exactly one of the two components of the superposition to the ground state. This optical transition contingent on spin was driven with the same broadband pulses that created the superposition through the use of a two pulse coherent control sequence. A final pulse affords measurement of the coherence of this "preentangled" state. PMID:24724666

Webster, L A; Truex, K; Duan, L-M; Steel, D G; Bracker, A S; Gammon, D; Sham, L J

2014-03-28

223

Transverse spin structure of the nucleon through target single-spin asymmetry in semi-inclusive deep-inelastic (e, e' ?^{±}_{}) reaction at Jefferson Lab  

NASA Astrophysics Data System (ADS)

Jefferson Lab (JLab) 12 GeV energy upgrade provides a golden opportunity to perform precision studies of the transverse spin and transverse-momentum-dependent structure in the valence quark region for both the proton and the neutron. In this paper, we focus our discussion on a recently approved experiment on the neutron as an example of the precision studies planned at JLab. The new experiment will perform precision measurements of target Single-Spin Asymmetries (SSA) from semi-inclusive electro-production of charged pions from a 40 cm long transversely polarized 3He target in deep-inelastic-scattering kinematics using 11 and 8.8 GeV electron beams. This new coincidence experiment in Hall A will employ a newly proposed solenoid spectrometer (SoLID). The large acceptance spectrometer and the high polarized luminosity will provide precise 4D ( x , z , PT and Q2) data on the Collins, Sivers, and pretzelosity asymmetries for the neutron through the azimuthal angular dependence. The full 2 ? azimuthal angular coverage in the lab is essential in controlling the systematic uncertainties. The results from this experiment, when combined with the proton Collins asymmetry measurement and the Collins fragmentation function determined from the e+e- collision data, will allow for a quark flavor separation in order to achieve a determination of the tensor charge of the d quark to a 10% accuracy. The extracted Sivers and pretzelosity asymmetries will provide important information to understand the correlations between the quark orbital angular momentum and the nucleon spin and between the quark spin and nucleon spin.

Gao, H.; Gamberg, L.; Chen, J.-P.; Qian, X.; Qiang, Y.; Huang, M.; Afanasev, A.; Anselmino, M.; Avakian, H.; Cates, G.; Chudakov, E.; Cisbani, E.; de Jager, C.; Garibaldi, F.; Hu, B. T.; Jiang, X.; Kumar, K. S.; Li, X. M.; Lu, H. J.; Meziani, Z.-E.; Ma, B.-Q.; Mao, Y. J.; Peng, J.-C.; Prokudin, A.; Schlegel, M.; Souder, P.; Xiao, Z. G.; Ye, Y.; Zhu, L.

2011-01-01

224

Quantum control and measurement of spins in laser cooled gases  

NASA Astrophysics Data System (ADS)

Quantum information processing (QIP) requires three important ingredients: (i) preparing a desired initial quantum state, usually highly pure; (ii) controlling the dynamical evolution, usually via a desired unitary transformation; (iii) measuring the desired information encoded in the final quantum state. Many physical platforms are being developed for QIP, including trapped ions, semiconductor quantum dots, and atoms in optical lattices. In these cases, it is the spins of the system that encode the quantum information. Spins are natural carriers of quantum information given their long coherence times and our ability to control them with a variety of external electromagnetic fields. In addition, spins in laser-cooled atomic gases are an excellent testbed for exploring QIP protocols because of our ability to initially prepare highly pure states and employ the well-developed tools of quantum optics and coherent spectroscopy. In this talk I will give an overview of recent theory and experiment in the control and measurement of spins in laser-cooled atomic gases. We consider the hyperfine magnetic sublevels in the ground electronic states of ^133Cs, a 16-dimensional Hilbert space. We can explore all three ingredients described above: preparation of an arbitrary superposition state, evolution through an arbitrary unitary matrix, and readout through quantum state reconstruction of the full density matrix. We employ the tools of optimal quantum control and quantum estimation theory. The implementation involves atoms controlled by radio-frequency, microwave, a optical fields, and measured via polarization spectroscopy. The experiment is performed in the group of Prof. Poul S. Jessen, University of Arizona. This work was supported by the National Science Foundation.

Deutsch, Ivan

2012-10-01

225

The birthrate and initial spin period of single radio pulsars  

NASA Astrophysics Data System (ADS)

A statistical analysis of radio pulsar data is presented. The basic theory behind the analysis is discussed, and all the selection effects of the major pulsar surveys are considered in detail, paying particular attention to those that depend on pulsar period. The birthrate of pulsars is estimated to be one pulsar in about 56 years, and the local rate in the solar neighborhood is estimated to be one pulsar in about 90,000 yr/sq kpc. The calculations confirm an earlier result from Vivekanand and Narayan (1981) that many pulsars are born with initial periods as slow as 0.5 s. Three possibilities are discussed for the correlation between initial spin period and magnetic field. The issue of a luminosity model for radio pulsars is also addressed, and the model of Lyne et al. (1985) is rejected in favor of a power-law model, which fits the data better.

Narayan, Ramesh

1987-08-01

226

Soft-Fermion-Pole Mechanism to Single Spin Asymmetry in Hadronic Pion Production  

NASA Astrophysics Data System (ADS)

Single spin asymmetry (SSA) is a twist-3 observable in the collinear factorization approach. We present a twist-3 single-spin-dependent cross section formula for the pion production in pp-collision, p?p-->?X, relevant to RHIC experiments. In particular, we calculate the soft-fermion-pole (SFP) contribution to the cross section from the quark-gluon correlation functions. We show that its effect can be as large as the soft-gluon-pole (SGP) contribution owing to the large SFP partonic hard cross section, even though the derivative of the SFP function does not participate in the cross section.

Koike, Yuji; Tomita, Tetsuya

2009-08-01

227

Soft-Fermion-Pole Mechanism to Single Spin Asymmetry in Hadronic Pion Production  

SciTech Connect

Single spin asymmetry (SSA) is a twist-3 observable in the collinear factorization approach. We present a twist-3 single-spin-dependent cross section formula for the pion production in pp-collision, p{sup a}rrow upp->piX, relevant to RHIC experiments. In particular, we calculate the soft-fermion-pole (SFP) contribution to the cross section from the quark-gluon correlation functions. We show that its effect can be as large as the soft-gluon-pole (SGP) contribution owing to the large SFP partonic hard cross section, even though the derivative of the SFP function does not participate in the cross section.

Koike, Yuji; Tomita, Tetsuya [Department of Physics, Niigata University, Ikarashi, Niigata 950-2181 (Japan)

2009-08-04

228

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

229

Single-transverse-spin asymmetries: From deep inelastic scattering to hadronic collisions  

SciTech Connect

We study single-spin asymmetries in semi-inclusive deep inelastic scattering with transversely polarized target. Based on the QCD factorization approach, we consider Sivers and Collins contributions to the asymmetries. We fit simple parametrizations for the Sivers and Collins functions to the recent HERMES data, and compare to results from COMPASS. Using the fitted parametrizations for the Sivers functions, we predict the single-transverse-spin asymmetries for various processes in pp collisions at the Relativistic Heavy Ion Collider, including the Drell-Yan process and angular correlations in dijet and jet-plus-photon production. These asymmetries are found to be sizable at forward rapidities.

Vogelsang, Werner [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); RIKEN BNL Research Center, Building 510A, Brookhaven National Laboratory, Upton, New York 11973 (United States); Yuan Feng [RIKEN BNL Research Center, Building 510A, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2005-09-01

230

Dynamics of a single Mn spin in a quantum dot: The role of magnetic fields in Faraday and Voigt geometry  

Microsoft Academic Search

A theoretical analysis of the optically driven spin dynamics of a single Mn atom in a quantum dot in the presence of magnetic fields in different geometries is presented. When a magnetic field in Faraday configuration is applied, the Mn spin can be flipped from its initial state into each of its six spin eigenstates via optical excitation and manipulation

D. E. Reiter; T. Kuhn; V. M. Axt; P. Machnikowski

2009-01-01

231

Liquidlike correlations in single-crystalline Y2Mo2O7: An unconventional spin glass  

NASA Astrophysics Data System (ADS)

The spin-glass behavior of Y2Mo2O7 has remained a puzzle for nearly three decades. Free of bulk disorder within the resolution of powder diffraction methods, it is thought that this material is a rare realization of a spin glass resulting from weak disorder such as bond disorder or local lattice distortions. Here we report on the single-crystal growth of Y2Mo2O7. Using neutron scattering, we present isotropic magnetic diffuse scattering occurring below the spin-glass transition. Our attempts to model the diffuse scattering using a computationally exhaustive search of a class of simple spin Hamiltonians show no agreement with the experimentally observed energy-integrated (diffuse) neutron scattering. This suggests that spin degrees of freedom are insufficient to describe this system. Indeed, a T2 temperature dependence in the heat capacity and density functional theory calculations hint at the presence of a significant frozen degeneracy in both the spin and orbital degrees of freedom resulting from spin-orbital coupling (Kugel-Khomskii type) and random fluctuations in the Mo environment at the local level.

Silverstein, H. J.; Fritsch, K.; Flicker, F.; Hallas, A. M.; Gardner, J. S.; Qiu, Y.; Ehlers, G.; Savici, A. T.; Yamani, Z.; Ross, K. A.; Gaulin, B. D.; Gingras, M. J. P.; Paddison, J. A. M.; Foyevtsova, K.; Valenti, R.; Hawthorne, F.; Wiebe, C. R.; Zhou, H. D.

2014-02-01

232

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

PubMed

The 3d-4f mixed metallacrowns frequently show single-molecule magnetic behavior. We have used magnetic Compton scattering to characterize the spin structure and orbital interactions in three isostructural metallacrowns: Gd2Mn4, Dy2Mn4, and Y2Mn4. These data allow the direct determination of the spin only contribution to the overall magnetic moment. We find that the lanthanide 4f spin in Gd2Mn4 and Dy2Mn4 is aligned parallel to the Mn 3d spin. For Y2Mn4 (manganese-only spin) we find evidence for spin delocalization into the O 2p orbitals. Comparing the magnetic Compton scattering data with SQUID studies that measure the total magnetic moment suggests that Gd2Mn4 and Y2Mn4 have only a small orbital contribution to the moment. In contrast, the total magnetic moment for Dy2Mn4 MCs is much larger than the spin-only moment, demonstrating a significant orbital contribution to the overall magnetic moment. Overall, these data provide direct insight into the correlation of molecular design with molecular magnetic properties. PMID:24625070

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

2014-04-01

233

Intrinsic spin-relaxation induced negative tunnel magnetoresistance in a single-molecule magnet  

NASA Astrophysics Data System (ADS)

We investigate theoretically the effects of intrinsic spin-relaxation on the spin-dependent transport through a single-molecule magnet (SMM), which is weakly coupled to ferromagnetic leads. The tunnel magnetoresistance (TMR) is obtained by means of the rate-equation approach including not only the sequential but also the cotunneling processes. It is shown that the TMR is strongly suppressed by the fast spin-relaxation in the sequential region and can vary from a large positive to slight negative value in the cotunneling region. Moreover, with an external magnetic field along the easy-axis of SMM, a large negative TMR is found when the relaxation strength increases. Finally, in the high bias voltage limit the TMR for the negative bias is slightly larger than its characteristic value of the sequential region; however, it can become negative for the positive bias caused by the fast spin-relaxation.

Xie, Haiqing; Wang, Qiang; Xue, Hai-Bin; Jiao, HuJun; Liang, J.-Q.

2013-06-01

234

All-optical spin manipulation of a single manganese atom in a quantum dot.  

PubMed

For a CdTe quantum dot doped with a single Mn atom we analyze the dynamics of the Mn spin when the dot is excited by ultrashort laser pulses. Because of the exchange interaction with the Mn atom, electron and hole spins can flip and induce a change of the Mn spin. Including both heavy and light-hole excitons and using suitable pulse sequences, angular momentum can be transferred from the light to the Mn system while the exciton system returns to its ground state. We show that by a series of ultrashort laser pulses the Mn spin can be selectively driven into each of its six possible orientations on a picosecond timescale. By applying a magnetic field the total switching time and the required number of pulses can be strongly reduced. PMID:19518830

Reiter, D E; Kuhn, T; Axt, V M

2009-05-01

235

Spin-Polarized Electron Scattering at Single Oxygen Adsorbates on a Magnetic Surface  

NASA Astrophysics Data System (ADS)

Scanning tunneling spectroscopy (STS) on the system of isolated oxygen atoms adsorbed on the double layer of Fe on W(110) shows highly anisotropic spatial oscillations in the local density of states in the vicinity of the adsorbates. We explain this in terms of a single-particle model as electron waves being scattered by the potential induced by the presence of the oxygen atoms. Analysis of the wavelength of the standing electron waves and comparison with ab initio spin-resolved electronic structure calculations reveal that minority-spin bands of d-like symmetry are involved in the scattering process. By applying spin-polarized STS, we observe this standing wave pattern on one particular type of magnetic domain of Fe on W(110) only, thereby proving that the standing electron waves are highly spin polarized.

von Bergmann, K.; Bode, M.; Kubetzka, A.; Heide, M.; Blügel, S.; Wiesendanger, R.

2004-01-01

236

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

SciTech Connect

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

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

1988-05-13

237

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

PubMed

Entanglement has a central role in fundamental tests of quantum mechanics as well as in the burgeoning field of quantum information processing. Particularly in the context of quantum networks and communication, a main challenge is the efficient generation of entanglement between stationary (spin) and propagating (photon) quantum bits. Here we report the observation of quantum entanglement between a semiconductor quantum dot spin and the colour of a propagating optical photon. The demonstration of entanglement relies on the use of fast, single-photon detection, which allows us to project the photon into a superposition of red and blue frequency components. Our results extend the previous demonstrations of single-spin/single-photon entanglement in trapped ions, neutral atoms and nitrogen-vacancy centres to the domain of artificial atoms in semiconductor nanostructures that allow for on-chip integration of electronic and photonic elements. As a result of its fast optical transitions and favourable selection rules, the scheme we implement could in principle generate nearly deterministic entangled spin-photon pairs at a rate determined ultimately by the high spontaneous emission rate. Our observation constitutes a first step towards implementation of a quantum network with nodes consisting of semiconductor spin quantum bits. PMID:23151586

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

2012-11-15

238

Controlling the Competition between Optically Induced Ultrafast Spin-Flip Scattering and Spin Transport in Magnetic Multilayers  

NASA Astrophysics Data System (ADS)

The study of ultrafast dynamics in magnetic materials provides rich opportunities for greater fundamental understanding of correlated phenomena in solid-state matter, because many of the basic microscopic mechanisms involved are as-yet unclear and are still being uncovered. Recently, two different possible mechanisms have been proposed to explain ultrafast laser induced magnetization dynamics: spin currents and spin-flip scattering. In this work, we use multilayers of Fe and Ni with different metals and insulators as the spacer material to conclusively show that spin currents can have a significant contribution to optically induced magnetization dynamics, in addition to spin-flip scattering processes. Moreover, we can control the competition between these two processes, and in some cases completely suppress interlayer spin currents as a sample undergoes rapid demagnetization. Finally, by reversing the order of the Fe/Ni layers, we experimentally show that spin currents are directional in our samples, predominantly flowing from the top to the bottom layer.

Turgut, Emrah; La-o-vorakiat, Chan; Shaw, Justin M.; Grychtol, Patrik; Nembach, Hans T.; Rudolf, Dennis; Adam, Roman; Aeschlimann, Martin; Schneider, Claus M.; Silva, Thomas J.; Murnane, Margaret M.; Kapteyn, Henry C.; Mathias, Stefan

2013-05-01

239

Magnetic-field-induced quantum criticality in a spin- S planar ferromagnet with single-ion anisotropy  

NASA Astrophysics Data System (ADS)

The effects of single-ion anisotropy on quantum criticality in a d-dimensional spin- S planar ferromagnet is explored by means of the two-time Green's function method. We work at the Tyablikov decoupling level for exchange interactions and the Anderson-Callen decoupling level for single-ion anisotropy. In our analysis a longitudinal external magnetic field is used as the non-thermal control parameter and the phase diagram and the quantum critical properties are established for suitable values of the single-ion anisotropy parameter D. We find that the single-ion anisotropy has sensible effects on the structure of the phase diagram close to the quantum critical point. However, for values of the uniaxial crystal-field parameter below a positive threshold, the conventional magnetic-field-induced quantum critical scenario remains unchanged.

Mercaldo, M. T.; Rabuffo, I.; De Cesare, L.; Caramico D'Auria, A.

2013-08-01

240

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

241

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

National Technical Information Service (NTIS)

We demonstrate a technique to nanofabricate nitrogen vacancy (NV) centers in diamond based on broad-beam nitrogen implantation through apertures in electron beam lithography resist. This method enables high-throughput nanofabrication of single NV centers ...

C. D. Weis D. D. Awschalom D. M. Toyli G. D. Fuchs T. Schenkel

2011-01-01

242

Controllable coupling between a charge qubit and a spin ensemble  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

243

Controlling chaotic behaviour for spin generator and Rossler dynamical systems with feedback control  

Microsoft Academic Search

Different methods are proposed to control chaotic behaviour of the Nuclear Spin Generator (NSG) and Rossler continuous dynamical systems. Linear and nonlinear feedback control techniques are used to suppress chaos. The stabilization of unstable fixed point or unstable periodic solution of chaotic behaviour is achieved. The controlled system is stable under some conditions on the parameters of the system. Stability

A. Hegazi; H. N. Agiza; M. M. El-Dessoky

2001-01-01

244

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

245

ELECTRON SPIN RESONANCE OF AN X-RAY IRRADIATED SINGLE CRYSTAL OF DIKETOPIPERAZINE  

Microsoft Academic Search

The electron spin resonance of an x irradiated single crystal of ; diketopiperazine was measured at 9 Gc\\/sec for various orientations of the crystal ; in the static magnetic field. From an analysis of the hyperfine structure ; observed, the components of the hyperfine interaction tensor for the radical ; produced by the irradiation were calculated. The principal values for

W. C. Lin; C. A. McDowell

1963-01-01

246

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

Microsoft Academic Search

Manipulation of the spin-states of a quantum dot by purely electrical means\\u000ais a highly desirable property of fundamental importance for the development of\\u000aspintronic devices such as spin-filters, spin-transistors and single-spin\\u000amemory as well as for solid-state qubits. An electrically gated quantum dot in\\u000athe Coulomb blockade regime can be tuned to hold a single unpaired spin-1\\/2,\\u000awhich is

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

2008-01-01

247

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

Microsoft Academic Search

We explore how electric fields can be used to drive single spin resonance in quantum dots without AC magnetic fields. We calculate the g tensor for a single electron in a semiconductor quantum dot as a function of electric field along the growth direction of the dot. The calculations are based on an eight-band envelope-function formalism[1]. The growth-direction g factor

Joseph Pingenot

2005-01-01

248

Electronic spin transport and spin precession in single graphene layers at room temperature  

Microsoft Academic Search

Electronic transport in single or a few layers of graphene is the subject of intense interest at present. The specific band structure of graphene, with its unique valley structure and Dirac neutrality point separating hole states from electron states, has led to the observation of new electronic transport phenomena such as anomalously quantized Hall effects, absence of weak localization and

Nikolaos Tombros; Csaba Jozsa; Mihaita Popinciuc; Harry T. Jonkman; Bart J. van Wees

2007-01-01

249

Spin-waves in Antiferromagnetic Single-crystal LiFePO4  

SciTech Connect

Spin-wave dispersions in the antiferromagnetic state of single-crystal LiFePO{sub 4} were determined by inelastic neutron scattering measurements. The dispersion curves measured from the (0,1,0) reflection along both a* and b* reciprocal-space directions reflect the anisotropic coupling of the layered Fe{sup 2+} (S=2) spin system. The spin-wave dispersion curves were theoretically modeled using linear spin-wave theory by including in the spin Hamiltonian in-plane nearest- and next-nearest-neighbor interactions (J{sub 1} and J{sub 2}), inter-plane nearest-neighbor interactions (J{perpendicular}) and a single-ion anisotropy (D). A weak (0,1,0) magnetic peak was observed in elastic neutron scattering studies of the same crystal indicating that the ground state of the staggered iron moments is not along the (0,1,0) direction, as previously reported from polycrystalline samples studies, but slightly rotated away from this axis.

Li, Jiying [Ames Laboratory; Garlea, Vasile O [ORNL; Zarestky, Jarel [Ames Laboratory; Vaknin, D. [Ames Laboratory

2006-01-01

250

Quantum optical control of spins and excitons in semiconductor quantum dots  

NASA Astrophysics Data System (ADS)

In this dissertation we present a theory of quantum optical control of spins and excitons in semiconductor quantum dots. Energy structure and optical selection rules of multi-excitons in a semiconductor quantum dot are constructed from a microscopic model. The effect of the electron-hole exchange interaction is discussed. Nonlinear coherent optical effects in a single quantum dot are investigated. A general theory is developed to calculate non-perturbatively the cross-polarized and the co-polarized pump-probe spectra as a function of laser intensity. Aulter-Towners configuration is proposed to be the best scenario to observe the onset of Rabi splitting. This is the prerequisite for performing the Rabi rotation in the multi-exciton space. A theory of fast quantum optical control of exciton dynamics in quantum dots is investigated. The concept of the optimal control is proposed. Pulse design using the average Hamiltonian method and the numerical method is explored. It is shown that by using the shaped-pulses the operation time can be reduced by an order of magnitude. Natural gates instead of the conventional universal quantum gates are used to reduce the number of quantum gates needed for any quantum algorithm. Pulse sequences for the Deutsch-Jozsa algorithm and the quantum Fourier transform are designed explicitly to illustrate the concept of optimal control. Quantum trajectories method is used to simulate the dynamics of the quantum computer including the decoherence process. It is shown that the quantum algorithm can be finished within the decoherence time of the system with high fidelity. To explore the control of single electron spin in quantum dots, adiabatic Raman transition via single ? system is extended to perform arbitrary spin rotations in a single charged quantum dot. Adiabatic condition is discussed. Extension to other ? system is explored. To couple and control the spins localized in neighboring quantum dots, a theory of optical RKKY interaction is developed. This indirect interaction is mediated by the photoexcited delocalized electron-hole pairs or excitons. The general formula and the numerical value of the effective exchange constant are presented. Application to quantum computation is discussed.

Chen, Pochung

251

High-spin states in the single-closed-shell nucleus 142Nd  

Microsoft Academic Search

The excited states of 14260Nd82 have been studied using the 140Ce(alpha, 2ngamma)142Nd and 142Ce(alpha, 4gamma)142Nd reactions. Singles gamma-ray, gamma-gamma coincidence spectra and angular distributions of gamma-rays with respect to the beam direction have been measured. Excited states up to 6.7 MeV with spin values up to 14 are populated. The energy spacings between the lower excited states with spin values

L.-E. de Geer; A. Kerek; Z. Haratym; J. Kownacki; J. Ludziejewski

1975-01-01

252

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

SciTech Connect

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

Hwang, D.S. [Department of Physics, Sejong University, Seoul 143-747 (Korea, Republic of)

2005-05-06

253

Generator for single bubbles of controllable size  

NASA Astrophysics Data System (ADS)

A new type of apparatus for the production of single bubbles of adjustable size is presented. A single bubble is generated by injecting a short burst of gas into a liquid channel flow. The radius of the bubble can be varied continuously from 300 ?m up to a 3 mm by adjusting the timing of a valve injecting the gas. The device works also in liquids with variable pressure and can be microcomputer controlled.

Ohl, C. D.

2001-01-01

254

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

SciTech Connect

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

YUAN, F.

2006-12-18

255

FEM Optimization of Spin Forming Using a Fuzzy Control Algorithm  

NASA Astrophysics Data System (ADS)

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

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

2004-06-01

256

Controllable valley and spin transport in ferromagnetic silicene junctions  

NASA Astrophysics Data System (ADS)

We investigate charge, valley, and spin transports in a normal/ferromagnetic/normal silicene junction. We show that the charge, valley, and spin conductances in this junction oscillate with the length of the ferromagnetic silicene. It is also found that the current through this junction is valley and spin polarized due to the coupling between valley and spin degrees of freedom, and the valley and spin polarizations can be tuned by local application of a gate voltage. In particular, we find a fully valley and spin polarized current by applying the electric field. We also obtain the condition for observing the fully valley and spin polarized current.

Yokoyama, Takehito

2013-06-01

257

Electron spin resonance signal of Luttinger liquids and single-wall carbon nanotubes.  

PubMed

A comprehensive theory of electron spin resonance (ESR) for a Luttinger liquid state of correlated metals is presented. The ESR measurables such as the signal intensity and the linewidth are calculated in the framework of Luttinger liquid theory with broken spin rotational symmetry as a function of magnetic field and temperature. We obtain a significant temperature dependent homogeneous line broadening which is related to the spin-symmetry breaking and the electron-electron interaction. The result crosses over smoothly to the ESR of itinerant electrons in the noninteracting limit. These findings explain the absence of the long-sought ESR signal of itinerant electrons in single-wall carbon nanotubes when considering realistic experimental conditions. PMID:18851238

Dóra, B; Gulácsi, M; Koltai, J; Zólyomi, V; Kürti, J; Simon, F

2008-09-01

258

Single and Double Spin Asymmetries for Semi-Inclusive Deep Inelastic Scattering on Proton and Deuteron  

NASA Astrophysics Data System (ADS)

Transverse momentum dependent (TMD) parton distribution functions encode information on the transverse motion of quarks and gluons inside the nucleon, and may help us understand their orbital angular momentum. The TMDs can be accessed from the target and double spin asymmetries of semi-inclusive deep inelastic scattering (SIDIS) reactions, where the asymmetries, AUL and ALL are convolutions of the fragmentation functions and the TMDs. The EG1-DVCS experiment with CLAS at Jefferson Lab measured semi-inclusive pion production on longitudinally polarized proton and deuteron targets with polarized electrons of 6 GeV. We will show preliminary results on target single spin asymmetries and target-beam double spin asymmetries for these reactions.

Koirala, Suman; Kuhn, Sebastian

2013-04-01

259

Random spin freezing in single crystalline Ce2CuSi3  

NASA Astrophysics Data System (ADS)

We present the results of ac and dc susceptibility, magnetization and magnetic relaxation measurements performed on single crystalline Ce2CuSi3, a hexagonal AlB2-type nonmagnetic atom disorder compound, with the magnetic field applied along two typical crystallographic directions, i.e. H?c-axis and H//c-axis. For both the directions, spin-glass state is confirmed to form at low temperature with almost the same spin freezing temperature Tf (~2.07K), initial frequency shift ?Tf (~0.015) and activation energy Ea/kB (~10.04 K) in zero dc field. Strong magnetic anisotropy is also found to be a significant feature of this compound. The experimental results and the dynamical analyses suggest that spin-glass behavior is intrinsic to the title compound.

Li, D. X.; Nimori, S.; Ohta, S.; Yamamura, Y.; Shikama, Y.

2012-12-01

260

Evidence for a single-spin azimuthal asymmetry in semi-inclusive pion electroproduction  

PubMed

Single-spin asymmetries for semi-inclusive pion production in deep-inelastic scattering have been measured for the first time. A significant target-spin asymmetry of the distribution in the azimuthal angle straight phi of the pion relative to the lepton scattering plane was formed for pi(+) electroproduction on a longitudinally polarized hydrogen target. The corresponding analyzing power in the sinstraight phi moment of the cross section is 0.022+/-0.005+/-0.003. This result can be interpreted as the effect of terms in the cross section involving chiral-odd spin distribution functions in combination with a chiral-odd fragmentation function that is sensitive to the transverse polarization of the fragmenting quark. PMID:10990607

2000-05-01

261

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

SciTech Connect

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

Avakian, H; Bosted, P; Elouadrhiri, L; Adhikari, K P; Aghasyan, M; Amaryan, M; Anghinolfi, M; Baghdasaryan, H; Ball, J; Battaglieri, M; Bedlinskiy, I; Biselli, A S; Branford, D; Briscoe, W J; Brooks, W; Carman, D S; Casey, L; Cole, P L; Collins, P; Crabb, D; Crede, V; D& #x27; Angelo, A; Daniel, A; Dashyan, N; DeVita, R; DeSanctis, E; Deur, A; Dey, B; Dhamija, S; Dickson, R; Djalali, C; Dodge, G; Doughty, D; Dupre, R; El Alaoui, A; Eugenio, P; Fegan, S; Fersch, M; Guler, N; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Hassall, N; Heddle, D; Hicks, K; Holtrop, M; Ilieva, Y; Ireland, D G; Isupov, E L; Jawalkar, S S; Jo, H S; Joo, K; Keller, D; Khandaker, M; Khetarpal,; Kim, W; Klein, A; Klein, F J; Konczykowski, P; Kubarovsky, V; Kuhn, S E; Kuleshov, S V; Kuznetsov, V; Livingston, K; Lu, H Y; Markov, N; Mayer, M; McAndrew, J; McCracken, M E; McKInnon, B; Meyer, C A; Mineeva, T; Mirazita, M; Mokeev, V; Moreno, B; Moriya, K; Morrison, B; Moutarde, H; Munevar, E; Nadel-Turonski, P; Nasseripour, R; Niccolai, S; Niculescu, G; Niculescu, I; Niroula, M R; Osipenko, M; Ostrovidov, A I; Paremuzyan, R; Park, K; Park, S; Pasyuk, E; Anefalos Pereira, S; Perrin, Y; Pisano, S; Pogorelko, O; Price, J W; Procureur, S; Prok, Protopopescu; Raue, B A; Ricco, G; Ripani, M; Rosner, G; Rossi, P; Sabatie, F; Saini, M S; Salamanca, J; Salgado, C; Schumacher, R A; Seder, E; Seraydaryan, H; Sharabian, Y G; Sober, D I; Sokhan, D; Stapanyan, S S; Stepanyan, S; Stoler, P; Strauch, S; Suleiman, R; Taiuti, M; Tedeschi, D J; Tkachenko, S; Ungaro, M; Vernarsky, B; Vineyard, M F; Voutier, E; Watts, D P; Weinstein, L B; Weygand, D P; Wood, M H; Zhang, J; Zhao, B

2010-12-01

262

Determination of Spin Polarization of Half-Metallic Single Crystal CrO2  

NASA Astrophysics Data System (ADS)

Highly spin-polarized materials play a crucial role in magnetoelectronic devices. The tunneling magnetoresistance of a magnetic tunnel junction scales with the spin polarization (P) of the ferromagnetic electrodes. Of particular interest are the half-metallic ferromagnets with P = 100%, which can be verified by the determination of their P values. Recently, it has been shown that a superconductor/metal point contact can be used to measure the spin-polarization P of the conduction electrons in the metal.^1,2 The point contact Andreev reflection (PCAR) technique is based on the fact that Andreev reflection probabilities are suppressed by the imbalance of the density of states for two spin directions in the ferromagnet. Accurate quantitative determination of spin polarization value, however, requires analyses of the entire conductance curves and taking into account interfacial scattering barrier.^3 Using this technique with quantitative analyses, we have measured the spin polarization of a number of common ferromagnets (Fe, Co, and Ni), La_0.7Sr_0.3MnO3 and CrO_2. Most importantly, we have found P in excess of 96% in single-crystal CrO2 films.^4 To date, CrO2 is the first and only half-metallic ferromagnet confirmed from spin current measurements. [1]. Upadhyay et al., Phys. Rev. Lett. 81, 3247 (1998). [2]. Soulen et al., Science 282, 85 (1998). [3]. Strijkers, Ji, Yang, Chien, and Byers, Phys. Rev. B 63, 104510 (2001). [4]. Ji, Strijkers, Yang, Chien, Byers, Anguelouch, Xiao, and Gupta, Phys. Rev. Lett. 86, 5585 (2001).

Ji, Yi

2002-03-01

263

Mechanical read out of a single electron spin in a carbon nanotube  

NASA Astrophysics Data System (ADS)

The spin of a single electron in a suspended carbon nanotube can be read out by using its coupling to the nano-mechanical motion of the nanotube. To show this, we consider a single electron confined within a quantum dot formed by the suspended carbon nanotube. The spin-orbit interaction induces a coupling between the spin and one of the bending modes of the suspended part of the nanotube [1]. We simulate the response of the system to the external driving with a Jaynes-Cummings model by solving the quantum master equation. Using parameters comparable to those used in recent experiments, we show how information of the spin state of the system can be acquired by measuring its mechanical motion [2]. The mechanical motion can be detected by observing the current through a nearby charge detector. [4pt] [1] A. Palyi, P.R. Struck, M. Rudner, K. Flensberg, G. Burkard, Phys. Rev. Lett. 108, 206811 (2012).[0pt] [2] H. Wang, P. R. Struck, G. Burkard, manuscript in preparation.

Burkard, Guido; Wang, Heng; Struck, Philipp

2013-03-01

264

Reversible Polarization Control of Single Photon Emission  

Microsoft Academic Search

We present reversible and a-priori control of the polarization of a photon emitted by a single molecule by introducing a nanoscale metal object in its near field. It is experimentally shown that, with the metal close to the emitter, the polarization ratio of the emission can be varied by a factor of 2. The tunability of polarization decays, when the

Robert J. Moerland; Tim H. Taminiau; Lukas Novotny; Hulst van Niek F; Laurens Kuipers

2008-01-01

265

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

266

Soft-fermion-pole contribution to single-spin asymmetry for pion production in pp collisions  

NASA Astrophysics Data System (ADS)

We study the single transverse spin asymmetry for the inclusive pion production in the nucleon-nucleon collision, pp??X, based on the twist-3 mechanism in the collinear factorization. We derive the soft-fermion-pole (SFP) contribution to the twist-3 single-spin-dependent cross section associated with the twist-3 quark-gluon correlation functions in the polarized nucleon. We find that the SFP can give rise to a large effect to the asymmetry A owing to the large partonic hard cross sections with the large color factor, if the SFP function has a similar magnitude as the soft-gluon-pole (SGP) function, in spite of the absence of the “derivative term” for the SFP function unlike for the SGP function.

Koike, Yuji; Tomita, Tetsuya

2009-05-01

267

On the Relation Between Mechanisms for Single-Transverse-SpinAsymmetries  

SciTech Connect

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

Koike, Yuji; Vogelsang, Werner; Yuan, Feng

2007-11-05

268

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.

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

2012-01-01

269

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

PubMed

Engineering quantum particle systems, such as quantum simulators and quantum cellular automata, relies on full coherent control of quantum paths at the single particle level. Here we present an atom interferometer operating with single trapped atoms, where single particle wave packets are controlled through spin-dependent potentials. The interferometer is constructed from a sequence of discrete operations based on a set of elementary building blocks, which permit composing arbitrary interferometer geometries in a digital manner. We use this modularity to devise a space-time analogue of the well-known spin echo technique, yielding insight into decoherence mechanisms. We also demonstrate mesoscopic delocalization of single atoms with a separation-to-localization ratio exceeding 500; this result suggests their utilization beyond quantum logic applications as nano-resolution quantum probes in precision measurements, being able to measure potential gradients with precision 5 x 10(-4) in units of gravitational acceleration g. PMID:22665771

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

2012-06-19

270

Single spin asymmetries in high energy reactions and nonperturbative QCD effects  

Microsoft Academic Search

We discuss some experimental and theoretical results on single spin asymmetries (SSA) in high energy lepton-hadron and hadron-hadron\\u000a reactions. In particular, recent results on meson SSA obtained by HERMES are considered in detail. We also discuss the SSA\\u000a results obtained recently by COMPASS, as well as those from BRAHMS, PHENIX and STAR. Special attention is paid to a possible\\u000a nonperturbative

A. E. Dorokhova; N. I. Kochelev; W.-D. Nowak

2009-01-01

271

Spin-Lattice Relaxation-Time Measurements of Trivalent Iron in Single-Crystal Calcite  

Microsoft Academic Search

The spin-lattice relaxation time for the M=-12-->12 transition of trivalent iron in single-crystal calcite has been measured at X band by pulse recovery from 1.4 to 45 K and by spectral line broadening from 40 to 195 K. The resulting transition-probability data are well described by the sum of a direct-process term and a Raman-process term, the latter having a

S. A. Marshall; S. V. Nistor; R. A. Serway

1972-01-01

272

Preparing optical thick films for planar waveguides with single spin-coating processes  

Microsoft Academic Search

With the help of methylcellulose, an organic binder, SiO2\\/TiO2\\/methylcellulose hybrid thick films were prepared by a sol–gel technique with single spin-coating processes. After annealing at 70 °C for an hour, 2.5-?m crack-free and dense organic–inorganic hybrid optical films with a refractive index of 1.537 were achieved. Optical losses of waveguides made up of these films and ordinary slide glass substrates are

X. Y. Zhang; J. Yang; C. M. Wu; Z. M. Wang; M. L. Chen; J. Y. Zhang

2005-01-01

273

Preparing optical thick films for planar waveguides with single spin-coating processes  

Microsoft Academic Search

With the help of methylcellulose, an organic binder, SiO2\\/TiO2\\/methylcellulose hybrid thick films were prepared by a sol gel technique with single spin-coating processes. After annealing at 70 °C for an hour, 2.5-mum crack-free and dense organic inorganic hybrid optical films with a refractive index of 1.537 were achieved. Optical losses of waveguides made up of these films and ordinary slide

X. Y. Zhang; J. Yang; C. M. Wu; Z. M. Wang; M. L. Chen; J. Y. Zhang

2005-01-01

274

Optical control of coherent interactions between quantum dot electron spins  

Microsoft Academic Search

Coherent interactions between spins in quantum dots are a key requirement for quantum gates. We have performed pump-probe experiments in which pulsed lasers emitting at different photon energies manipulate two distinct subsets of electron spins within an inhomogeneous InGaAs quantum dot ensemble. The spin dynamics are monitored through their precession about an external magnetic field. These measurements demonstrate spin precession

S. Spatzek; A. Greilich; Sophia E. Economou; A. Schwan; S. Varwig; D. R. Yakovlev; D. Reuter; A. D. Wieck; T. L. Reinecke; M. Bayer

2010-01-01

275

Controlling a nanowire spin-orbit qubit via electric-dipole spin resonance.  

PubMed

A semiconductor nanowire quantum dot with strong spin-orbit coupling (SOC) can be used to achieve a spin-orbit qubit. In contrast to a spin qubit, the spin-orbit qubit can respond to an external ac electric field, an effect called electric-dipole spin resonance. Here we develop a theory that can apply in the strong SOC regime. We find that there is an optimal SOC strength ?(opt)=?2/2, where the Rabi frequency induced by the ac electric field becomes maximal. Also, we show that both the level spacing and the Rabi frequency of the spin-orbit qubit have periodic responses to the direction of the external static magnetic field. These responses can be used to determine the SOC in the nanowire. PMID:24010464

Li, Rui; You, J Q; Sun, C P; Nori, Franco

2013-08-23

276

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

277

Electrical control of spin dynamics in finite one-dimensional systems  

NASA Astrophysics Data System (ADS)

We investigate the possibility of the electrical control of spin transfer in monoatomic chains incorporating spin impurities. Our theoretical framework is the mixed quantum-classical (Ehrenfest) description of the spin dynamics, in the spirit of the s-d model, where the itinerant electrons are described by a tight-binding model while localized spins are treated classically. Our main focus is on the dynamical exchange interaction between two well-separated spins. This can be quantified by the transfer of excitations in the form of transverse spin oscillations. We systematically study the effect of an electrostatic gate bias Vg on the interconnecting channel and we map out the long-range dynamical spin transfer as a function of Vg. We identify regions of Vg giving rise to significant amplification of the spin transmission at low frequencies and relate this to the electronic structure of the channel.

Pertsova, A.; Stamenova, M.; Sanvito, S.

2011-10-01

278

Spin measurements and control of cold atoms using spin-orbit fields  

NASA Astrophysics Data System (ADS)

We show that by switching on a spin-orbit interaction in a cold-atom system, experiencing a Zeeman-like coupling to an external field, e.g., in a Bose-Einstein condensate, one can simulate a quantum measurement on a precessing spin. Depending on the realization, the measurement can access both the ergodic and the Zeno regimes, while the time dependence of the spin's decoherence may vary from a Gaussian to an inverse fractional power law. Back action of the measurement forms time- and coordinate-dependent profiles of the atoms' density, resulting in its translation, spin-dependent fragmentation, and appearance of interference patterns.

Sokolovski, D.; Sherman, E. Ya.

2014-04-01

279

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

280

Detection of single micron-sized magnetic bead and magnetic nanoparticles using spin valve sensors for biological applications  

Microsoft Academic Search

We have fabricated a series of highly sensitive spin valve sensors on a micron scale that successfully detected the presence of a single superparamagnetic bead (Dynabeads M-280, 2.8 mum in diameter), and thus showed suitability for identifying biomolecules labeled by such magnetic beads. By polarizing the magnetic microbead on a spin valve sensor with a dc magnetic field and modulating

Guanxiong Li; Vikram Joshi; Robert L. White; Shan X. Wang; Jennifer T. Kemp; Chris Webb; Ronald W. Davis; Shouheng Sun

2003-01-01

281

Single-parameter quantum charge and spin pumping in armchair graphene nanoribbons  

NASA Astrophysics Data System (ADS)

We investigate quantum charge and spin pumping in armchair graphene nanoribbons under a single ac gate voltage connected with nonmagnetic/ferromagnetic leads via the nonequilibrium Green's function method. In the case of nonmagnetic leads, where only part of the nanoribbon is subject to an ac gate voltage to break the left-right spatial symmetry, we discover that peaks of the charge pumping current appear at the Fermi energies around the sub-band edges in the ac-field-free region of the nanoribbon. In the case of ferromagnetic leads with the lead magnetizations being antiparallel to break the left-right symmetry, similar peaks appear in the spin pumping current when the Fermi energies are around the edges of the the majority-spin sub-bands in the ferromagnetic leads. All these peaks originate from the pronounced symmetry breaking in the transmissions with energies being around the corresponding sub-band edges. Moreover, we predict a pure spin current in the case of ferromagnetic leads with the whole graphene nanoribbon under an ac gate voltage. The ac-field-strength and ac-field-frequency dependencies of the pumping current are also investigated with the underlying physics revealed.

Zhou, Y.; Wu, M. W.

2012-08-01

282

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

NASA Astrophysics Data System (ADS)

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

2013-12-01

283

Switching of a quantum dot spin valve by single molecule magnets  

NASA Astrophysics Data System (ADS)

We explore theoretically the spin transport in nanostructures consisting of a gold quantum dot bridging nonmagnetic electrodes and two Mn12-Ph single molecule magnets (SMMs) that are thiol bonded to the dot but are not in direct contact with the electrodes. We find that reversal of the magnetic moment of either SMM by the application of a magnetic field leads to a large change in the resistance of the dot, i.e., a strong spin-valve effect. We show that this phenomenon arises from the following physical principle: The spin-dependent molecular orbitals that extend over the dot and both SMMs change drastically when the magnetic moment of either SMM is reversed, resulting in a large change in the conduction via those orbitals. The same physics may also be responsible for the spin-valve phenomena discovered recently in carbon nanotube quantum dots with rare-earth SMMs [M. Urdampilleta , Nat. Mater.1476-112210.1038/nmat3050 10, 502 (2011)].

Rostamzadeh Renani, Fatemeh; Kirczenow, George

2013-03-01

284

Full spin control in 2DEGs with no magnetic fields  

NASA Astrophysics Data System (ADS)

A properly chosen closed spin transport path in the plane of a III-V semiconductor quantum well suffices for arbitrary spin manipulation of conduction electrons about any desired axis. This feature of spin transport relies on the non-commutativity of the precession matrices associated with non-colinear path segments. The electron spin rotation depends solely on the path geometry, not the speed of the spin along the path. Simple closed paths have been found which will perform arbitrary spin rotations along arbitrary axes with no net spatial displacement of the spins. The paths differ depending on the form of the internal effective magnetic fields induced by crystal asymmetry, growth asymmetry, and strain and electric fields. This work was supported by an ONR MURI.

Moehlmann, B. J.; Flatté, M. E.

2009-03-01

285

Full spin control in 2DEGs with no magnetic fields  

NASA Astrophysics Data System (ADS)

A properly chosen closed spin transport path in the plane of a III-V semiconductor quantum well suffices for arbitrary spin manipulation of conduction electrons about any desired axis. This feature of spin transport relies on the non-commutativity of the precession matrices associated with non-colinear path segments. The electron spin rotation depends solely on the path geometry, not the speed of the spin along the path. Simple closed paths have been found which will perform arbitrary spin rotations along arbitrary axes with no net spatial displacement of the spins. The paths differ depending on the form of the internal effective magnetic fields induced by crystal asymmetry, growth asymmetry, and strain and electric fields. This work was supported by an ONR MURI.

Moehlmann, B. J.; Flatté, Michael

2009-11-01

286

Optical control of magnetization and spin blockade in graphene quantum dots  

NASA Astrophysics Data System (ADS)

We show that the magnetization of triangular graphene quantum dots with zigzag edges can be manipulated optically. When the system is charge neutral, the magnetic moment can be first erased by addition of a single electron spin with a gate, then restored by absorption of a photon. The conversion of a single photon to a magnetic moment results in a many-body effect, optical spin blockade. The effect demonstrated here can potentially lead to efficient spin to photon conversion, quantum memories, and single-photon detectors.

Güçlü, A. D.; Hawrylak, P.

2013-01-01

287

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

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

288

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

NASA Astrophysics Data System (ADS)

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

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

2008-05-01

289

High-dynamic-range magnetometry with a single electronic spin in diamond.  

PubMed

Magnetic sensors capable of detecting nanoscale volumes of spins allow for non-invasive, element-specific probing. The error in such measurements is usually reduced by increasing the measurement time, and noise averaging the signal. However, achieving the best precision requires restricting the maximum possible field strength to much less than the spectral linewidth of the sensor. Quantum entanglement and squeezing can then be used to improve precision (although they are difficult to implement in solid-state environments). When the field strength is comparable to or greater than the spectral linewidth, an undesirable trade-off between field strength and signal precision occurs. Here, we implement novel phase estimation algorithms on a single electronic spin associated with the nitrogen-vacancy defect centre in diamond to achieve an ?8.5-fold improvement in the ratio of the maximum field strength to precision, for field magnitudes that are large (?0.3 mT) compared to the spectral linewidth of the sensor (?4.5 µT). The field uncertainty in our approach scales as 1/T(0.88), compared to 1/T(0.5) in the standard measurement approach, where T is the measurement time. Quantum phase estimation algorithms have also recently been implemented using a single nuclear spin in a nitrogen-vacancy centre. Besides their direct impact on applications in magnetic sensing and imaging at the nanoscale, these results may prove useful in improving a variety of high-precision spectroscopy techniques. PMID:22179565

Nusran, N M; Momeen, M Ummal; Dutt, M V Gurudev

2012-02-01

290

Polytype control of spin qubits in silicon carbide  

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

291

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

292

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

PubMed

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

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

2010-08-20

293

Controlling the competition between optically induced ultrafast spin-flip scattering and spin transport in magnetic multilayers.  

PubMed

The study of ultrafast dynamics in magnetic materials provides rich opportunities for greater fundamental understanding of correlated phenomena in solid-state matter, because many of the basic microscopic mechanisms involved are as-yet unclear and are still being uncovered. Recently, two different possible mechanisms have been proposed to explain ultrafast laser induced magnetization dynamics: spin currents and spin-flip scattering. In this work, we use multilayers of Fe and Ni with different metals and insulators as the spacer material to conclusively show that spin currents can have a significant contribution to optically induced magnetization dynamics, in addition to spin-flip scattering processes. Moreover, we can control the competition between these two processes, and in some cases completely suppress interlayer spin currents as a sample undergoes rapid demagnetization. Finally, by reversing the order of the Fe/Ni layers, we experimentally show that spin currents are directional in our samples, predominantly flowing from the top to the bottom layer. PMID:23705737

Turgut, Emrah; La-o-Vorakiat, Chan; Shaw, Justin M; Grychtol, Patrik; Nembach, Hans T; Rudolf, Dennis; Adam, Roman; Aeschlimann, Martin; Schneider, Claus M; Silva, Thomas J; Murnane, Margaret M; Kapteyn, Henry C; Mathias, Stefan

2013-05-10

294

Optical control of collisional population flow between molecular electronic states of different spin multiplicity  

NASA Astrophysics Data System (ADS)

In this work we demonstrate optical control of the singlet-triplet probability distribution in the outcome of a collisional process involving lithium dimers and argon atoms. The control is achieved using the Autler-Townes effect to manipulate the spin character of a spin-orbit coupled pair of levels serving as a "gateway" between the singlet and triplet electronic state manifolds.

Ahmed, E. H.; Pan, X.; Huennekens, J.; Lyyra, A. M.

2014-06-01

295

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

296

Implementation of Dynamically Corrected Gates on a Single Electron Spin in Diamond  

NASA Astrophysics Data System (ADS)

Precise control of an open quantum system is critical to quantum information processing but is challenging due to inevitable interactions between the quantum system and the environment. We demonstrated experimentally a type of dynamically corrected gates using only bounded-strength pulses on the nitrogen-vacancy centers in diamond. The infidelity of quantum gates caused by a nuclear-spin bath is reduced from being the second order to the sixth order of the noise-to-control-field ratio, which offers greater efficiency in reducing infidelity. The quantum gates have been protected to the limit essentially set by the spin-lattice relaxation time T1. Our work marks an important step towards fault-tolerant quantum computation in realistic systems.

Rong, Xing; Geng, Jianpei; Wang, Zixiang; Zhang, Qi; Ju, Chenyong; Shi, Fazhan; Duan, Chang-Kui; Du, Jiangfeng

2014-02-01

297

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

PubMed

Precise control of an open quantum system is critical to quantum information processing but is challenging due to inevitable interactions between the quantum system and the environment. We demonstrated experimentally a type of dynamically corrected gates using only bounded-strength pulses on the nitrogen-vacancy centers in diamond. The infidelity of quantum gates caused by a nuclear-spin bath is reduced from being the second order to the sixth order of the noise-to-control-field ratio, which offers greater efficiency in reducing infidelity. The quantum gates have been protected to the limit essentially set by the spin-lattice relaxation time T1. Our work marks an important step towards fault-tolerant quantum computation in realistic systems. PMID:24580578

Rong, Xing; Geng, Jianpei; Wang, Zixiang; Zhang, Qi; Ju, Chenyong; Shi, Fazhan; Duan, Chang-Kui; Du, Jiangfeng

2014-02-01

298

Optical control of single excitons in semiconductor quantum dots  

NASA Astrophysics Data System (ADS)

The fundamental building block of quantum information processing technologies is the quantum-bit a ‘qubit.’ These technologies require the ability to prepare, control, and read out a qubit state. Spins confined in self-assembled quantum dots are promising candidates for a quantum bit, because semiconductors are compatible with mature modern opto- and micro-electronics. These quantum dot systems offer two more advantages: they are excellent interfaces between the spin state—an anchored qubit and a photon—a ‘flying qubit’ and they provide means to coherently control the spin qubit by ultrashort optical pulses. In this review, we thoroughly discuss the qubit provided by an optically-excited electron in a quantum dot–the exciton qubit. We demonstrate its spin state initialization, coherent control and read-out using ultrashort optical pulses.

Kodriano, Y.; Schmidgall, E. R.; Benny, Y.; Gershoni, D.

2014-05-01

299

Pulse FT NMR of non-equilibrium states of half-integer spin quadrupolar nuclei in single crystals.  

PubMed

For quadrupolar nuclei with spin quantum numbers equal to 3/2, 5/2 and 7/2, the intensities of the NMR transitions in a single crystal are examined as a function of the rf excitation flip angle. Single-quantum NMR intensities are calculated using density matrix theory beginning under various non-equilibrium conditions and are compared with those determined experimentally. As a representative spin-3/2 system, the flip-angle dependence of the (23)Na NMR intensities of a single crystal of NaNO(3) was investigated beginning with the inversion of the populations associated with one of the satellite transitions. Subsequently, the populations of both satellite transitions were inverted using highly frequency-selective hyperbolic secant pulses. Calculated and experimental intensities are in good agreement. As an example of a spin-5/2 system, the flip-angle dependence of the (27)Al NMR transition intensities was determined using a single crystal of sapphire, Al(2)O(3), starting under different nuclear spin population conditions. The experimental trends mimicked those predicted by the density matrix calculations but the agreement was not as good as for the spin-3/2 case. Some SIMPSON simulations were also carried out to confirm the results generated by our density matrix calculations. The theoretical flip-angle behavior of the NMR transition intensities obtained from a spin-7/2 spin system is also discussed. PMID:19962334

Nakashima, Thomas T; Harris, Kristopher J; Wasylishen, Roderick E

2010-02-01

300

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

301

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

NASA Astrophysics Data System (ADS)

We model 100 ps pulse switching dynamics of orthogonal spin transfer (OST) devices that employ an out-of-plane polarizer and an in-plane polarizer. Simulation results indicate that increasing the spin polarization ratio, CP = PIPP/POPP, results in deterministic switching of the free layer without over-rotation (360° rotation). By using spin torque asymmetry to realize an enhanced effective PIPP, we experimentally demonstrate this behavior in OST devices in parallel to anti-parallel switching. Modeling predicts that decreasing the effective demagnetization field can substantially reduce the minimum CP required to attain deterministic switching, while retaining low critical switching current, Ip ˜ 500 ?A.

Park, Junbo; Ralph, D. C.; Buhrman, R. A.

2013-12-01

302

Self-stabilising attitude control for spinning tethered formations  

NASA Astrophysics Data System (ADS)

The paper analyses the dynamics of a spinning tethered formation where the tethered units are modelled as extended rigid bodies. The system, composed by two platforms linked by a flexible tether a few hundreds of meters long, constitutes the building block of more complex tethered architectures utilised in proposed space interferometry missions. The issue investigated herein is the transfer of a collimated beam from one platform to another in the presence of environmental perturbations and structural vibrations affecting the position and attitude of the two tethered units. We propose to damp residual oscillations and limit the effect of environmental torques with the aid of two passive dampers placed at the tether attachment point. When the damping system is properly tuned, this approach has the considerable advantage of rapidly bringing the system to a minimum energy configuration (zero residual vibrations) without any external control force. Numerical results show the effectiveness of the proposed control strategy and provide an important element towards the implementation of future space-based observatories and formation-flying demonstration mission based on tether-connected architectures.

Menon, Carlo; Bombardelli, Claudio

2007-05-01

303

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

SciTech Connect

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

Gong, Zhirui [University of Hong Kong, The; Liu, G. B. [University of Hong Kong, The; Yu, Hongyi [University of Hongkong; Xiao, Di [Carnegie Mellon University; Cui, Xiaodong [University of Hong Kong, The; Xu, Xiaodong [University of Washington; Yao, Wang [University of Hong Kong, The

2013-01-01

304

Controllable spin-dynamics cycles and ERASE functionality on quasilinear molecular ions  

NASA Astrophysics Data System (ADS)

We present an ab initio investigation of the ?-process-based ultrafast spin manipulation on positively charged two-magnetic-center molecular ions with a nonmagnetic bridging atom O in-between. Multiple spin-switching and spin-transfer scenarios are derived on the quasilinear structure [Fe-O-Co]+, which are used to build two closed, irreversible spin-dynamics cycles with respect to the spin localization and orientation. A mechanism addressing the "ERASE" functionality is proposed by properly exploiting the irreversibility of some laser-induced spin-manipulation scenarios, and the resulting Shannon entropy change is analyzed. Such controllable spin-dynamics cycles and logic functionality demonstrate promising applications in the design of spintronic devices.

Li, Chun; Zhang, Shaobin; Jin, Wei; Lefkidis, Georgios; Hübner, Wolfgang

2014-05-01

305

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

306

Reversible polarization control of single photon emission.  

PubMed

We present reversible and a-priori control of the polarization of a photon emitted by a single molecule by introducing a nanoscale metal object in its near field. It is experimentally shown that, with the metal close to the emitter, the polarization ratio of the emission can be varied by a factor of 2. The tunability of polarization decays, when the metal is displaced by typically 30 nm. Calculations based on the multiple multipole method agree well with our experiments and predict even further enhancement with a suitable nanoantenna design. PMID:18193913

Moerland, Robert J; Taminiau, Tim H; Novotny, Lukas; van Hulst, Niek F; Kuipers, Laurens

2008-02-01

307

Spin-orbit splitting in single-layer MoS2 revealed by triply resonant Raman scattering.  

PubMed

Although new spintronic devices based on the giant spin-orbit splitting of single-layer MoS(2) have been proposed, such splitting has not been studied effectively in experiments. This Letter reports the valence band spin-orbit splitting in single-layer MoS(2) for the first time, probed by the triply resonant Raman scattering process. We found that upon 325 nm laser irradiation, the second order overtone and combination Raman modes of single-layer MoS(2) are dramatically enhanced. Such resonant Raman enhancement arises from the electron-two-phonon triple resonance via the deformation potential and Fröhlich interaction. As a sensitive and precise probe for the spin-orbit splitting, the triply resonant Raman scattering will provide a new and independent route to study the spin characteristics of MoS(2). PMID:24093287

Sun, Linfeng; Yan, Jiaxu; Zhan, Da; Liu, Lei; Hu, Hailong; Li, Hong; Tay, Ben Kang; Kuo, Jer-Lai; Huang, Chung-Che; Hewak, Daniel W; Lee, Pooi See; Shen, Ze Xiang

2013-09-20

308

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

309

Bias-controllable spin beam splitter based on antiparallel double ?-magnetic-barrier nanostructure  

NASA Astrophysics Data System (ADS)

We investigate Goos-Hänchen (GH) effect of spin beams in antiparallel double ?-magnetic-barrier (MB) nanostructure under an applied bias, which can be experimentally realized by depositing two metallic ferromagnetic (FM) stripes on top and bottom of the semiconductor heterostructure. GH shifts for spin beams accross this device, is numerically calculated, with the help of the stationary phase method. It is shown that a sizable spin polarization of GH shifts still exists in this device under an applied bias. It also is shown that both magnitude and sign of spin polarization of GH shifts can be controlled by adjusting the applied bias. These interesting properties may provide an effective approach to spin injection, and this device can be used as a bias-controllable spin beam splitter.

Kong, Yong-Hong; Fu, Xi; Li, Ai-Hua; Chen, Xiao-Lin

2013-03-01

310

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

311

Twist-3 Single-Spin Asymmetry for SIDIS and its Azimuthal Structure  

NASA Astrophysics Data System (ADS)

We derive the complete twist-3 single-spin-dependent cross section for semi-inclusive DIS, ep?-->e?X, associated with the complete set of the twist-3 quark-gluon correlation functions in the transversely polarized nucleon, extending our previous study. The cross section consists of five independent structure functions with different azimuthal dependences, consistently with the transverse-momentum-dependent (TMD) factorization approach in the low qT region. Correspondence with the inclusive DIS limit and comparison with the TMD approach are briefly discussed.

Koike, Yuji; Tanaka, Kazuhiro

2009-08-01

312

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

313

Generating entangled spin states for quantum metrology by single-photon detection  

NASA Astrophysics Data System (ADS)

We propose and analyze a probabilistic but heralded scheme to generate pure, entangled, non-Gaussian states of collective spin in large atomic ensembles by means of single-photon detection. One photon announces the preparation of a Dicke state, while two or more photons announce Schrödinger cat states. The method produces pure states even for finite photon detection efficiency and weak atom-photon coupling. The entanglement generation can be made quasideterministic by means of repeated trial and feedback, enabling metrology beyond the standard quantum limit.

McConnell, Robert; Zhang, Hao; ?uk, Senka; Hu, Jiazhong; Schleier-Smith, Monika H.; Vuleti?, Vladan

2013-12-01

314

Unified picture for single transverse-spin asymmetries in hard-scattering processes.  

PubMed

Using lepton-pair production in hadron-hadron collisions as an example, we explore the relation between two well-known mechanisms for single-transverse-spin asymmetries in hard processes: twist-three quark-gluon correlations when the pair's transverse momentum is large, q perpendicular > Lambda QCD, and time-reversal-odd and transverse-momentum-dependent parton distributions when q perpendicular is much less than the pair's mass. We find that, although the two mechanisms each have their own domain of validity, they describe the same physics in the kinematic region where they overlap. This unifies the two mechanisms and imposes an important constraint on phenomenological studies. PMID:17026293

Ji, Xiangdong; Qiu, Jian-Wei; Vogelsang, Werner; Yuan, Feng

2006-08-25

315

Trigluon correlations and single transverse spin asymmetry in open charm production  

NASA Astrophysics Data System (ADS)

We study the single transverse-spin asymmetry for open charm production in the semiinclusive lepton-hadron deep inelastic scattering (SIDIS) and pp collision. Within collinear factorization approach, we find that the asymmetry is sensitive to the twist-3 trigluon correlation functions in the proton. With a simple model for the trigluon correlation functions, we estimate the asymmetry in SIDIS for both COMPASS and eRHIC kinematics, as well as in pp collision at RHIC energy. We discuss the possibilities of extracting the trigluon correlation functions in these experiments.

Kang, Zhong-Bo; Qiu, Jian-Wei

2009-08-01

316

Calculation of Transverse-Momentum-Dependent Evolution for Sivers Transverse Single Spin Asymmetry Measurements  

NASA Astrophysics Data System (ADS)

The Sivers transverse single spin asymmetry (TSSA) is calculated and compared at different scales using the transverse-momentum-dependent (TMD) evolution equations applied to previously existing extractions. We apply the Collins-Soper-Sterman (CSS) formalism, using the version recently developed by Collins. Our calculations rely on the universality properties of TMD functions that follow from the TMD-factorization theorem. Accordingly, the nonperturbative input is fixed by earlier experimental measurements, including both polarized semi-inclusive deep inelastic scattering (SIDIS) and unpolarized Drell-Yan (DY) scattering. It is shown that recent preliminary COMPASS measurements are consistent with the suppression prescribed by TMD evolution.

Aybat, S. Mert; Prokudin, Alexei; Rogers, Ted C.

2012-06-01

317

Trigluon correlations and single transverse spin asymmetry in open charm production  

SciTech Connect

We study the single transverse-spin asymmetry for open charm production in the semiinclusive lepton-hadron deep inelastic scattering (SIDIS) and pp collision. Within collinear factorization approach, we find that the asymmetry is sensitive to the twist-3 trigluon correlation functions in the proton. With a simple model for the trigluon correlation functions, we estimate the asymmetry in SIDIS for both COMPASS and eRHIC kinematics, as well as in pp collision at RHIC energy. We discuss the possibilities of extracting the trigluon correlation functions in these experiments.

Kang Zhongbo; Qiu Jianwei [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States)

2009-08-04

318

Dynamical Monte Carlo investigation of spin reversal and nonequilibrium magnetization of single-molecule magnets  

NASA Astrophysics Data System (ADS)

In this paper, we combine thermal effects with Landau-Zener (LZ) quantum tunneling effects in a dynamical Monte Carlo (DMC) framework to produce satisfactory magnetization curves of single-molecule magnet (SMM) systems. We use the giant spin approximation for SMM spins and consider regular lattices of SMMs with magnetic dipolar interactions (MDIs). We calculate spin-reversal probabilities from thermal-activated barrier hurdling, direct LZ tunneling, and thermal-assisted LZ tunnelings in the presence of sweeping magnetic fields. We do systematical DMC simulations for Mn12 systems with various temperatures and sweeping rates. Our simulations produce clear step structures in low-temperature magnetization curves, and our results show that the thermally activated barrier hurdling becomes dominating at high temperature near 3 K and the thermal-assisted tunnelings play important roles at intermediate temperature. These are consistent with corresponding experimental results on good Mn12 samples (with less disorders) in the presence of little misalignments between the easy axis and applied magnetic fields, and therefore our magnetization curves are satisfactory. Furthermore, our DMC results show that the MDI, with the thermal effects, have important effects on the LZ tunneling processes, but both the MDI and the LZ tunneling give place to the thermal-activated barrier hurdling effect in determining the magnetization curves when the temperature is near 3 K. This DMC approach can be applicable to other SMM systems and could be used to study other properties of SMM systems.

Liu, Gui-Bin; Liu, Bang-Gui

2010-10-01

319

Single-photon-level optical storage in a solid-state spin-wave memory  

NASA Astrophysics Data System (ADS)

A long-lived quantum memory is a firm requirement for implementing a quantum repeater scheme. Recent progress in solid-state rare-earth-ion-doped systems justifies their status as very strong candidates for such systems. Nonetheless an optical memory based on spin-wave storage at the single-photon level has not been shown in such a system to date, which is crucial for achieving the long storage times required for quantum repeaters. In this paper we show that it is possible to execute a complete atomic frequency comb (AFC) scheme, including spin-wave storage, with weak coherent pulses of n¯=2.5±0.6 photons per pulse. We discuss in detail the experimental steps required to obtain this result and demonstrate the coherence of a stored time-bin pulse. We show a noise level of (7.1±2.3)×10-3 photons per mode during storage, and this relatively low noise level paves the way for future quantum optics experiments using spin waves in rare-earth-doped crystals.

Timoney, N.; Usmani, I.; Jobez, P.; Afzelius, M.; Gisin, N.

2013-08-01

320

The dispersion characteristics of the waves propagating in a spinning single-walled carbon nanotube  

NASA Astrophysics Data System (ADS)

As the nano-motor becomes a mechanical reality, its prototype can be envisaged as nano-sized rotating machinery at a situation, albeit for different purposes, like that in the first half of the 20th century during which rotor dynamics has contributed to boosting machine power capacity. Accordingly, we take the benefit of hindsight to develop a classical framework of vibration analysis. Essentially, the equations of motion are formulated to cope with both the special carbon-nanotube properties and the first author's previously developed spinning beam formalism, establishing a model satisfactorily verified by some available molecular dynamics (MD) data and classical spinning beam results extracted from the literature. The model is inexpensive based on continuum mechanics as an alternative to the less-flexible MD method for simulating wave motion of the spinning single-walled carbon nanotube, yielding several interesting phenomena, including the fall-off and splitting of the wave characteristic curves and the unexpected gyroscopic phase property. Potential applications are proposed.

Chan, K. T.; Zhao, Yapu

2011-10-01

321

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

PubMed Central

We built new hybrid devices consisting of chemical vapor deposition (CVD) grown carbon nanotube (CNT) transistors, decorated with TbPc2 (Pc = phthalocyanine) rare-earth based single-molecule magnets (SMMs). The drafting was achieved by tailoring supramolecular ?-? interactions between CNTs and SMMs. The magnetoresistance hysteresis loop measurements revealed steep steps, which we can relate to the magnetization reversal of individual SMMs. Indeed, we established that the electronic transport properties of these devices depend strongly on the relative magnetization orientations of the grafted SMMs. The SMMs are playing the role of localized spin polarizer and analyzer on the CNT electronic conducting channel. As a result, we measured magneto-resistance ratios up to several hundred percent. We used this spin valve effect to confirm the strong uniaxial anisotropy and the superparamagnetic blocking temperature (TB ~ 1 K) of isolated TbPc2 SMMs. For the first time, the strength of exchange interaction between the different SMMs of the molecular spin valve geometry could be determined. Our results introduce a new design for operable molecular spintronic devices using the quantum effects of individual SMMs.

Urdampilleta, Matias; Nguyen, Ngoc-Viet; Cleuziou, Jean-Pierre; Klyatskaya, Svetlana; Ruben, Mario; Wernsdorfer, Wolfgang

2011-01-01

322

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

NASA Technical Reports Server (NTRS)

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

Pantason, P.; Dickens, W.

1979-01-01

323

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

324

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

325

High temperature gate control of quantum well spin memory.  

PubMed

Time-resolved optical measurements in (110)-oriented GaAs/AlGaAs quantum wells show a tenfold increase of the spin-relaxation rate as a function of applied electric field from 20 to 80 kV cm(-1) at 170 K and indicate a similar variation at 300 K, in agreement with calculations based on the Rashba effect. Spin relaxation is almost field independent below 20 kV cm(-1) reflecting quantum well interface asymmetry. The results indicate the achievability of a voltage-gateable spin-memory time longer than 3 ns simultaneously with a high electron mobility. PMID:14683140

Karimov, O Z; John, G H; Harley, R T; Lau, W H; Flatté, M E; Henini, M; Airey, R

2003-12-12

326

High Temperature Gate Control of Quantum Well Spin Memory  

NASA Astrophysics Data System (ADS)

Time-resolved optical measurements in (110)-oriented GaAs/AlGaAs quantum wells show a tenfold increase of the spin-relaxation rate as a function of applied electric field from 20 to 80 kV cm-1 at 170K and indicate a similar variation at 300K, in agreement with calculations based on the Rashba effect. Spin relaxation is almost field independent below 20 kV cm-1 reflecting quantum well interface asymmetry. The results indicate the achievability of a voltage-gateable spin-memory time longer than 3ns simultaneously with a high electron mobility.

Karimov, O. Z.; John, G. H.; Harley, R. T.; Lau, W. H.; Flatté, M. E.; Henini, M.; Airey, R.

2003-12-01

327

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

PubMed Central

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, Jorg

2014-01-01

328

High-dynamic-range magnetometry with a single nuclear spin in diamond.  

PubMed

Sensors based on the nitrogen-vacancy defect in diamond are being developed to measure weak magnetic and electric fields at the nanoscale. However, such sensors rely on measurements of a shift in the Lamor frequency of the defect, so an accumulation of quantum phase causes the measurement signal to exhibit a periodic modulation. This means that the measurement time is either restricted to half of one oscillation period, which limits accuracy, or that the magnetic field range must be known in advance. Moreover, the precision increases only slowly (as T(-0.5)) with measurement time T (ref. 3). Here, we implement a quantum phase estimation algorithm on a single nuclear spin in diamond to combine both high sensitivity and high dynamic range. By achieving a scaling of the precision with time to T(-0.85), we improve the sensitivity by a factor of 7.4 for an accessible field range of 16 mT, or, alternatively, we improve the dynamic range by a factor of 130 for a sensitivity of 2.5 µT Hz(-1/2). Quantum phase estimation algorithms have also recently been implemented using a single electron spin in a nitrogen-vacancy centre. These methods are applicable to a variety of field detection schemes, and do not require quantum entanglement. PMID:22179568

Waldherr, G; Beck, J; Neumann, P; Said, R S; Nitsche, M; Markham, M L; Twitchen, D J; Twamley, J; Jelezko, F; Wrachtrup, J

2012-02-01

329

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

330

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

331

Control of spin ambiguity during reorientation of an energy dissipating body  

NASA Technical Reports Server (NTRS)

A quasi-rigid body initially spinning about its minor principal axis and experiencing energy dissipation will enter a tumbling mode and eventually reorient itself such that stable spin about its major principal axis is achieved. However, in this final state the body may be spinning in a positive or negative sense with respect to its major axis and aligned in a positive or negative sense with the inertially fixed angular momentum vector. This ambiguity can be controlled only through an active system. The associated dynamical formulations and simulations of uncontrolled reorientations are presented. Three control schemes are discussed and results offered for specific examples. These schemes include displacement of internal masses, spinning up of internal inertia, and reaction jets, all of which have demonstrated the ability to control spin ambiguity.

Kaplan, M. H.; Cenker, R. J.

1973-01-01

332

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

333

Magnetic field controlled reversal of ferroelectric polarization in conical spin ordered multiferroics: Monte Carlo simulation  

NASA Astrophysics Data System (ADS)

To understand the fascinating multiferroicity observed in CoCr2O4, Monte Carlo simulation is performed on a three-dimensional spinel lattice with classical Heisenberg spins. The conical spin order is confirmed to be the origin of the peculiar magnetoelectric behavior with coexisting magnetization and ferroelectric polarization. Furthermore, the simultaneous reversals of magnetization and polarization controlled by the external magnetic field are reproduced, consisting with the experimental observation qualitatively. It is revealed that, from the microscopic structures of spins, the axis of spin cone provides a ``handle,'' with which the magnetization and polarization can be reversed by the magnetic field easily.

Yao, Xiaoyan; Lo, Veng Cheong; Liu, Jun-Ming

2009-10-01

334

Optically Controlled Quantum Dot Spins for Scaleable Quantum Computing.  

National Technical Information Service (NTIS)

The objective of this program has been to work towards development of spin based quantum dots for optically driven quantum information processing. Using a combination of ultrahigh resolution laser spectroscopy to study the physics of the dots and ultrafas...

D. G. Steel

2005-01-01

335

Control of noise in magnetic multilayers by spin torque  

NASA Astrophysics Data System (ADS)

In this work we show that the stability of magnetic nanostructures can be enhanced by time-dependent spin momentum transfer. Building reliable magnetic devices at smaller scales need to address the issue of thermal noise. Using two commonly studied magnetic systems with multiple stable states at zero temperature as examples, we show that periodic spin torques can enhance the stability of the system and hence suppress the noise due to interwell transitions. In the case of weak periodic spin torques, stochastic resonance which is usually associated with ac magnetic fields is also manifested for non-conservative torques. In more complex systems with a relatively low energy barrier, it is shown that high frequency spin torques can inhibit interwell transitions and in effect suppress the telegraph noise due to the switching between neigboring states.

Rebei, Adnan

2012-02-01

336

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

NASA Astrophysics Data System (ADS)

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 sin?2? single spin asymmetry was observed for the first time indicating strong spin-orbit correlations for transversely polarized quarks in the longitudinally polarized proton.

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.; Anefalos Pereira, S.; 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.

2010-12-01

337

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

338

Voltage controlled electron spin dynamics in resonant tunnelling devices  

NASA Astrophysics Data System (ADS)

We investigate the electron spin dynamics in a p-type GaAs/AlAs resonant tunnelling device by measuring the time- and polarized-resolved photoluminescence (PL) from the GaAs quantum well under a high magnetic field (15 T). The voltage dependence of the PL transients have revealed various tunnelling processes with different time constants that give rise to distinct spin-polarized carriers injected into the double-barrier structure.

Galeti, H. V. A.; Brasil, M. J. S. P.; Gobato, Y. Galv ao; Henini, M.

2014-04-01

339

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

340

Voltage control of the spin dynamics of an exciton in a semiconductor quantum dot.  

PubMed

We report the observation of a spin-flip process in a quantum dot whereby a dark exciton with total angular momentum L = 2 becomes a bright exciton with L = 1. The spin-flip process is revealed in the decay dynamics following nongeminate excitation. We are able to control the spin-flip rate by more than an order of magnitude simply with a dc voltage. The spin-flip mechanism involves a spin exchange with the Fermi sea in the back contact of our device and corresponds to the high temperature Kondo regime. We use the Anderson Hamiltonian to calculate a spin-flip rate, and we find excellent agreement with the experimental results. PMID:16090209

Smith, J M; Dalgarno, P A; Warburton, R J; Govorov, A O; Karrai, K; Gerardot, B D; Petroff, P M

2005-05-20

341

Simultaneous time-optimal control of the inversion of two spin-(1/2) particles  

SciTech Connect

We analyze the simultaneous time-optimal control of two-spin systems. The two noncoupled spins, which differ in the value of their chemical offsets, are controlled by the same magnetic fields. Using an appropriate rotating frame, we restrict the study to the case of opposite shifts. We then show that the optimal solution of the inversion problem in a rotating frame is composed of a pulse sequence of maximum intensity and is similar to the optimal solution for inverting only one spin by using a nonresonant control field in the laboratory frame. An example is implemented experimentally using nuclear magnetic resonance techniques.

Assemat, E.; Lapert, M.; Sugny, D. [Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 5209 CNRS-Universite de Bourgogne, 9 Avenue A. Savary, BP 47 870, F-21078 Dijon Cedex (France); Zhang, Y.; Braun, M.; Glaser, S. J. [Department of Chemistry, Technische Universitaet Muenchen, Lichtenbergstrasse 4, D-85747 Garching (Germany)

2010-07-15

342

Spin dynamics in single-molecule magnets combining surface acoustic waves and high frequency electron paramagnetic resonance  

NASA Astrophysics Data System (ADS)

We report a new experimental technique that integrates high frequency surface acoustic waves (SAWs) with high frequency electron paramagnetic resonance (HFEPR) spectroscopy in order to measure spin dynamics on fast time scales in single-molecule magnets. After driving the system out of equilibrium by triggering magnetic avalanches, or simply by heating with short SAW pulses, the evolution of the spin populations within fixed energy levels is measured using HFEPR spectroscopy.

Hill, Stephen; Lawrence, Jonathan; Macia, Ferran; Hernandez, Joan Manel; Tejada, Javier; Santos, Paulo; Lampropoulos, Christos; Christou, George

2008-03-01

343

Spin dynamics in single-molecule magnets combining surface acoustic waves and high-frequency electron paramagnetic resonance  

NASA Astrophysics Data System (ADS)

We report an experimental technique that integrates high-frequency surface acoustic waves (SAWs) with high-frequency electron paramagnetic resonance (HFEPR) spectroscopy in order to measure spin dynamics on fast time scales in single-molecule magnets. After the system is driven out of equilibrium by triggering magnetic avalanches, or simply by heating with short SAW pulses, the evolution of the spin populations within fixed energy levels is measured using HFEPR spectroscopy.

Macià, F.; Lawrence, J.; Hill, S.; Hernandez, J. M.; Tejada, J.; Santos, P. V.; Lampropoulos, C.; Christou, G.

2008-01-01

344

Measurement of the Target Single-Spin Asymmetry in Quasi-Elastic 3He?(e,e')  

NASA Astrophysics Data System (ADS)

Experiment E05-015 measured the target single spin asymmetry, Ay for the neutron using the inclusive quasi-elastic 3He (e,e') in Hall A at Jefferson Lab with a vertically polarized 3He target at Q2 = 1.0 and 2.3 GeV. Ay is the asymmetry of target spin up versus target spin down, and is sensitive to the two-photon exchange amplitude. For my presentation I will discuss the goals of the experiment, my contributions and, my involvement in creating a new 3He Target lab at Longwood University.

St. John, Jeremy

2009-10-01

345

Elasticity of Single-Crystal Ferropericlase across the Spin Transition of Iron Investigated by Brillouin and Impulsive Spectroscopies  

NASA Astrophysics Data System (ADS)

Understanding the effect of the electronic spin transition of the iron on the elasticity of the lower-mantle ferropericlase (Mg,Fe)O is critical in our understanding of the seismic velocity structures of the Earth's lower mantle. Previous studies have reported inconsistent results about the elastic behavior of ferropericlase across the spin transition--- ISLS results showed that the spin transition is associated with softening of all elastic moduli by as much as 25% between 40 and 50 GPa (Crowhurst et al., 2008), whereas Brillouin spectroscopic studies revealed an increase in shear wave anisotropy across the transition. Inelastic X-ray scattering results, on the other hand, did not show any visible effects of the spin transition. To decipher the elasticity of the lower-mantle ferropericlase within the spin transition and in the low-spin state, we have used both Brillouin Light Scattering (BLS; sensitive to Vs) and Impulsive Stimulated Light Scattering (ISLS; sensitive to Vp) techniques to simultaneously measure the shear wave (BLS) and compressional wave (ISLS) velocities of a single-crystal ferropericlase in a high-pressure diamond anvil cell. Together with X-ray diffraction analyses, our results reveal various magnitudes of the effects of the spin transition on elastic moduli as well as Vp/Vs anisotropies of ferropericlase. These experimental results are used in thermal elastic modeling to address potential geophysical consequences of the spin transition in the lower mantle.

Tong, X.; Yang, J.; Lin, J.

2013-12-01

346

Quantum Control of the Spin-Orbit Interaction Using the Autler-Townes Effect  

NASA Astrophysics Data System (ADS)

The interaction between the spin and the orbital angular momenta (spin-orbit interaction) of the electron in an atom or a molecule often can be neglected or treated as a perturbation. However, when relativistic effects are not negligible, the spin-orbit interaction must be taken into account. It can cause mixing of electronic states of different spin multiplicity, with the degree of mixing dependent on the strength of the spin-orbit interaction as well as the energy separation between the interacting states. It is also well known that, in the presence of strong electromagnetic fields, the energy levels in atoms or molecules experience shifts in their positions due to the Autler-Townes (AT) effect. Thus control of the spin-orbit interaction can be realized by using resonant or nonresonant laser fields as an external control mechanism. We have demonstrated [1] experimentally such control of the spin-orbit interaction using resonant cw optical field. We show that the enhancement of the spin-orbit interaction between a pair of weakly interacting singlet-triplet rovibrational levels, 1^3?g^-(v=1, N=21, f)-G^1?g(v=12, J=21, f), depends on the Rabi frequency (laser power) of the control laser. The increase in the spin-orbit interaction due to the control field is observed as a change in the spin character of the individual components of the perturbed pair. [0pt] [1] E. H. Ahmed, S. Ingram, T. V. Kirova, O. Salihoglu, J. Huennekens, and A. M. Lyyra, PRL, 107, 163601 (2011).

Ahmed, Ergin; Ingram, Sonia; Kirova, Teodora; Salihoglu, Omer; Huennekens, John; Qi, Jianbing; Quan, Yafei; Lyyra, Marjatta

2013-03-01

347

General theory of feedback control of a nuclear spin ensemble in quantum dots  

NASA Astrophysics Data System (ADS)

We present a microscopic theory of the nonequilibrium nuclear spin dynamics driven by the electron and/or hole under continuous-wave pumping in a quantum dot. We show the correlated dynamics of the nuclear spin ensemble and the electron and/or hole under optical excitation as a quantum feedback loop and investigate the dynamics of the many nuclear spins as a nonlinear collective motion. This gives rise to three observable effects: (i) hysteresis, (ii) locking (avoidance) of the pump absorption strength to (from) the natural resonance, and (iii) suppression (amplification) of the fluctuation of weakly polarized nuclear spins, leading to prolonged (shortened) electron-spin coherence time. A single nonlinear feedback function is constructed which determines the different outcomes of the three effects listed above depending on the feedback being negative or positive. The general theory also helps to put in perspective the wide range of existing theories on the problem of a single electron spin in a nuclear spin bath.

Yang, Wen; Sham, L. J.

2013-12-01

348

Symmetric rotating-wave approximation for the generalized single-mode spin-boson system  

SciTech Connect

The single-mode spin-boson model exhibits behavior not included in the rotating-wave approximation (RWA) in the ultra and deep-strong coupling regimes, where counter-rotating contributions become important. We introduce a symmetric rotating-wave approximation that treats rotating and counter-rotating terms equally, preserves the invariances of the Hamiltonian with respect to its parameters, and reproduces several qualitative features of the spin-boson spectrum not present in the original rotating-wave approximation both off-resonance and at deep-strong coupling. The symmetric rotating-wave approximation allows for the treatment of certain ultra- and deep-strong coupling regimes with similar accuracy and mathematical simplicity as does the RWA in the weak-coupling regime. Additionally, we symmetrize the generalized form of the rotating-wave approximation to obtain the same qualitative correspondence with the addition of improved quantitative agreement with the exact numerical results. The method is readily extended to higher accuracy if needed. Finally, we introduce the two-photon parity operator for the two-photon Rabi Hamiltonian and obtain its generalized symmetric rotating-wave approximation. The existence of this operator reveals a parity symmetry similar to that in the Rabi Hamiltonian as well as another symmetry that is unique to the two-photon case, providing insight into the mathematical structure of the two-photon spectrum, significantly simplifying the numerics, and revealing some interesting dynamical properties.

Albert, Victor V.; Scholes, Gregory D.; Brumer, Paul [Department of Chemistry and Centre for Quantum Information and Quantum Control, University of Toronto, Toronto, M5S 3H6 (Canada)

2011-10-15

349

A scanning superconducting quantum interference device with single electron spin sensitivity  

NASA Astrophysics Data System (ADS)

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.

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

350

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

351

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

352

Sub-nanoscale, single-molecule, magnetic electronic switching from externally perturbed spin states in iron (III)-based complexes  

NASA Astrophysics Data System (ADS)

Both the temperature and pressure dependent spin state transition behaviour of two Fe(III) complexes will be exemplified. Such compounds are considered attractive as potential molecular switch devices for low power, low weight, high density nanomemory arrays in computer applications, or as sensors. Spin state configurations are readily investigated by 57Fe Mössbauer spectroscopy in the range 300-4 K, or at high pressures up to 20 GPa in diamond anvil cells. An iron coordination compound with the chemical formula {[FeIIIL2] [ClO4]}2·EtOH, where L- is a uni-negative ligand, HL is N-(pyridin-2-ylmethyl)salicylideneamine and EtOH is ethanol, is in the high spin (HS), 6A1g, state at room temperature. The onset of low spin (LS) population occurs at {\\sim }240 K and this increases monotonically as the temperature is lowered to 100 K. At 70 K the sample is predominantly in the LS state although a remnant {\\sim }12{%} HS population persists to the lowest recorded temperature of {\\sim }15 K. Thermodynamic parameters associated with the energy barrier between the two spin states are deduced from the temperature dependence of the equilibrium constant K. Pressure induced spin switching from the high moment HS state to the low moment LS electronic state in a haem-porphyrin [FeIII(TPP)(NCS)] will also be shown. Spin pairing onset occurs at a moderate pressure of {\\sim }5 GPa. HS and LS isomers exist in equilibrium up to {\\sim }12 GPa at room temperature. The sample is fully LS populated at P>12 GPa. Temperature and pressure dependent spin-spin relaxation is used to account for the pressure evolution of the (asymmetric) quadrupole split resonance profile. Density functional theory calculations, in conjunction with crystallographic data, are used to consider the structural response to such a spin state variation, perhaps suggesting the possibility of a mechanically operated single-molecule magnetic switch.

Hearne, G. R.; Munro, O.; Pearson, N.; Shongwe, M.

2005-03-01

353

Direct observation of Fe spin reorientation in single-crystalline YbFe6Ge6  

NASA Astrophysics Data System (ADS)

We have grown single crystals of YbFe6Ge6 and LuFe6Ge6 and characterized their anisotropic behaviour through low-field magnetic susceptibility, field-dependent magnetization, resistivity and heat capacity measurements. The Yb3+ valency is confirmed by LIII XANES measurements. YbFe6Ge6 crystals exhibit a field-dependent, sudden reorientation of the Fe spins at about 63 K, a unique effect in the RFe6Ge6 family (R = rare earths), where the Fe ions order anti-ferromagnetically with Neél temperatures above 450 K and the R ions' magnetism appears to behave independently. The possible origins of this unusual behaviour of the ordered Fe moments in this compound are discussed.

Avila, M. A.; Takabatake, T.; Takahashi, Y.; Bud'ko, S. L.; Canfield, P. C.

2005-11-01

354

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

355

Ultrafast quasiparticle dynamics in spin-density-wave LaOFeAs single crystal  

NASA Astrophysics Data System (ADS)

Ultrafast quasiparticle dynamics of single crystalline LaOFeAs were investigated by pump-probe measurement. The compound experiences structural and spin-density-wave (SDW) phase transitions at 150 K ( T S1) and 130 K ( T S2), respectively. The relaxation time of quasiparticles was somewhat temperature independent at high temperature but exhibited a sharp upturn at T S1 and reached the maximum at approximately T S2. The remarkable slowing down of quasiparticle relaxation time is caused by the formation of energy gap. By employing the Rothwarf-Taylor model analysis, we found that there should be already energy gaps opening just below the structural transition. The magnitude of SDW gap was identified to be 72 meV.

Chen, RongYan; Dong, Tao; Wang, HaiPeng; Wang, NanLin

2013-12-01

356

Quantum control of the spin-orbit interaction using the Autler-Townes effect.  

PubMed

We have demonstrated quantum control of the spin-orbit interaction based on the Autler-Townes (ac-Stark) effect in a molecular system using a cw optical field. We show that the enhancement of the spin-orbit interaction between a pair of weakly interacting singlet-triplet rovibrational levels, G?(1)?(g)(v=12,J=21,f)-1?(3)?(g)(-)(v=1,N=21,f), separated by 750 MHz in the lithium dimer, depends on the Rabi frequency (laser power) of the control laser. The increase in the spin-orbit interaction due to the control field is observed as a change in the spin character of the individual components of the perturbed pair. PMID:22107380

Ahmed, E H; Ingram, S; Kirova, T; Salihoglu, O; Huennekens, J; Qi, J; Guan, Y; Lyyra, A M

2011-10-14

357

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

PubMed

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

Mathonière, Corine; Lin, Hsiu-Jung; Siretanu, Diana; Clérac, Rodolphe; Smith, Jeremy M

2013-12-26

358

Slow exciton spin relaxation in single self-assembled In1-xGaxAs/GaAs quantum dots  

NASA Astrophysics Data System (ADS)

We calculate the acoustic phonon-assisted exciton spin relaxation via spin-orbit coupling in single self-assembled In1-xGaxAs/GaAs quantum dots using an atomistic empirical pseudopotential method. We show that the transition rate from bright to dark exciton states is zero under Hartree-Fock approximation. The exciton spin relaxation time obtained from sophisticated configuration interaction calculations is approximately 15-55 ?s in pure InAs/GaAs QDs and even longer in alloy dots. These results are more than three orders of magnitude longer than previous theoretical and experimental results (a few ns), but agree with more recent experiments which suggest that excitons have long spin-relaxation times (>1 ?s).

Wei, Hai; Guo, Guang-Can; He, Lixin

2014-06-01

359

Tunnel junction of helical edge states: Determining and controlling spin-preserving and spin-flipping processes through transconductance  

NASA Astrophysics Data System (ADS)

When a constriction is realized in a 2D quantum spin Hall system, electron tunneling between helical edge states occurs via two types of channels allowed by time-reversal symmetry, namely spin-preserving (p) and spin-flipping (f) tunneling processes. Determining and controlling the effects of these two channels is crucial to the application of helical edge states in spintronics. We show that, despite that the Hamiltonian terms describing these two processes do not commute, the scattering matrix entries of the related 4-terminal setup always factorize into products of p-term and f-term contributions. Such factorization provides an operative way to determine the transmission coefficients Tp and Tf related to each of the two processes, via transconductance measurements. Furthermore, these transmission coefficients are also found to be controlled independently by a suitable combination of two gate voltages applied across the junction. This result holds for an arbitrary profile of the tunneling amplitudes, including disorder in the tunnel region, enabling us to discuss the effect of the finite length of the tunnel junction, and the space modulation of both magnitude and phase of the tunneling amplitudes.

Sternativo, Pietro; Dolcini, Fabrizio

2014-01-01

360

Integration of adaptive process control with computational simulation for spin-forming  

SciTech Connect

Improvements in spin-forming capabilities through upgrades to a metrology and machine control system and advances in numerical simulation techniques were studied in a two year project funded by Laboratory Directed Research and Development (LDRD) at Lawrence Livermore National Laboratory. Numerical analyses were benchmarked with spin-forming experiments and computational speeds increased sufficiently to now permit actual part forming simulations. Extensive modeling activities examined the simulation speeds and capabilities of several metal forming computer codes for modeling flat plate and cylindrical spin-forming geometries. Shape memory research created the first numerical model to describe this highly unusual deformation behavior in Uranium alloys. A spin-forming metrology assessment led to sensor and data acquisition improvements that will facilitate future process accuracy enhancements, such as a metrology frame. Finally, software improvements (SmartCAM) to the manufacturing process numerically integrate the part models to the spin-forming process and to computational simulations.

Raboin, P. J., LLNL

1998-03-10

361

Controlled exchange interaction for quantum logic operations with spin qubits in coupled quantum dots  

SciTech Connect

A two-electron system confined in two coupled semiconductor quantum dots is investigated as a candidate for performing quantum logic operations with spin qubits. We study different processes of swapping the electron spins by a controlled switching on and off of the exchange interaction. The resulting spin swap corresponds to an elementary operation in quantum-information processing. We perform direct simulations of the time evolution of the two-electron system. Our results show that, in order to obtain the full interchange of spins, the exchange interaction should change smoothly in time. The presence of jumps and spikes in the time characteristics of the confinement potential leads to a considerable increase of the spin-swap time. We propose several mechanisms to modify the exchange interaction by changing the confinement potential profile and discuss their advantages and disadvantages.

Moskal, S.; Bednarek, S.; Adamowski, J. [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Cracow (Poland)

2007-09-15

362

Velocity of the high-spin low-spin interface inside the thermal hysteresis loop of a spin-crossover crystal, via photothermal control of the interface motion.  

PubMed

We investigated by optical microscopy the thermal transition of the spin-crossover dinuclear iron(II) compound [(Fe(NCSe)(py)(2))(2)(m-bpypz)]. In a high-quality crystal the high-spin (HS) low-spin (LS) thermal transition took place with a sizable hysteresis, at ~108 K and ~116 K on cooling and heating, respectively, through the growth of a single macroscopic domain with a straight LS and HS interface. The interface orientation was almost constant and its propagation velocity was close to ~6 and 26 ? m s(-1) for the on-cooling and on-heating processes, respectively. We found that the motion of the interface was sensitive to the intensity of the irradiation beam of the microscope, through a photothermal effect. By fine-tuning the intensity we could stop and even reverse the interface motion. This way we stabilized a biphasic state of the crystal, and we followed the spontaneous motion of the interface at different temperatures inside the thermal hysteresis loop. This experiment gives access for the first time to an accurate determination of the equilibrium temperature in the case of thermal hysteresis--which was not accessible by the usual quasistatic investigations. The temperature dependence of the propagation velocity inside the hysteretic interval was revealed to be highly nonlinear, and it was quantitatively reproduced by a dynamical mean-field theory, which made possible an estimate of the macroscopic energy barrier. PMID:23473199

Slimani, Ahmed; Varret, François; Boukheddaden, Kamel; Garrot, Damien; Oubouchou, Hassane; Kaizaki, Sumio

2013-02-22

363

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

NASA Astrophysics Data System (ADS)

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

Saffarzadeh, Alireza; Kirczenow, George

2013-03-01

364

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

365

Variable range hopping conductivity and spin glass behavior in spin-ladder Ba0.6K0.4Fe2Se3 single crystals  

NASA Astrophysics Data System (ADS)

Ba0.6K0.4Fe2Se3 (BKFS) single crystals were investigated by means of measurements of powder x-ray diffraction, temperature-dependent resistivity, anisotropic dc magnetization, ac magnetic susceptibility and specific heat. The powder x-ray diffraction indicates staggered iron displacements along the ladders with short and long Fe-Fe bond lengths (2.64(2) and 2.91(2) Å) variation. The resistivity of BKFS exhibits variable range hopping behavior with ln(?) ˜ T-1/2 at low temperature. The magnetic susceptibility ?(T) exhibits a sharp cusp at around 20 K in a zero-field-cooled process. The frequency-dependent ac magnetic susceptibility reveals that the cusp feature is attributable to spin glass behavior. The anisotropic ac magnetic susceptibility indicates that BKFS is probably an anisotropic Heisenberg-like spin glass with its easy magnetization plane perpendicular to the chain direction. The specific heat also supports an insulating and spin glass ground state. Extended Curie-Weiss behavior above 40 K was observed with a reduced effective moment (?eff = 1.66 ?B/Fe for H?b and ?eff = 1.82 ?B/Fe for H ? b) in BKFS, which is close to the spin-only magnetism with S=\\frac{1}{2}.

Bao, Jin-Ke; Feng, Chun-Mu; Luo, Yong-Kang; Jiang, Hao; Sun, Yun-Lei; Jiao, Wen-He; Shen, Chen-Yi; Xu, Zhu-An; Cao, Guang-Han

2014-01-01

366

Electric control of a {Fe4} single-molecule magnet in a single-electron transistor  

NASA Astrophysics Data System (ADS)

Using first-principles methods, we study theoretically the properties of an individual {Fe4} single-molecule magnet (SMM) attached to metallic leads in a single-electron transistor geometry. We show that the conductive leads do not affect the spin ordering and magnetic anisotropy of the neutral SMM. On the other hand, the leads have a strong effect on the anisotropy of the charged states of the molecule, which are probed in Coulomb blockade transport. Furthermore, we demonstrate that an external electric potential, modeling a gate electrode, can be used to manipulate the magnetic properties of the system. For a charged molecule, by localizing the extra charge with the gate voltage closer to the magnetic core, the anisotropy magnitude and spin ordering converges to the values found for the isolated {Fe4} SMM. We compare these findings with the results of recent quantum transport experiments in three-terminal devices.

Nossa, J. F.; Islam, M. F.; Canali, C. M.; Pederson, M. R.

2013-12-01

367

Controlling spin ordering in frustrated magnets via thin film heteroepitaxy  

NASA Astrophysics Data System (ADS)

Competing exchange interactions can give rise to varying degrees of frustration that manifest itself in noncollinear magnetic moment ordering or canonical geometric frustration in magnets with large ground-state degeneracies. Relieving this frustration has the potential to stabilize ground states inaccessible in the bulk. We demonstrate that heteroepitaxial lattice distortions can modify the strength of exchange interactions in thin films of the frustrated ferrimagnet, CuCr2O4. The reduction of magnetic frustration in CuCr2O4 through lattice distortions results in greater collinear spin ordering in CuCr2O4 thin films and an enhanced magnetization. We identify heteroepitaxial lattice distortions as a method to tune spin functionality and potentially lift ground-state degeneracies more broadly in frustrated magnets.

Iwata-Harms, Jodi M.; Wong, Franklin J.; Alaan, Urusa S.; Kirby, B. J.; Borchers, Julie A.; Toney, Michael F.; Nelson-Cheeseman, Brittany B.; Liberati, Marco; Arenholz, Elke; Suzuki, Yuri

2012-06-01

368

Controlling spin diffusion by tailored rf-irradiation schemes  

NASA Astrophysics Data System (ADS)

Spin-diffusion type polarization transfer among heteronuclei, e.g., 13C or 15N, plays an important role in many solid-state NMR experiments for structure determination of proteins. In such experiments, chemical-shift compensation is provided by the proton bath (‘proton-driven') which can be improved by radio-frequency irradiation of the protons. Here, we address the problem that the polarization-transfer rates depend not only on the intermolecular distance but also on the chemical-shift difference of the two spins. We introduce rf-modulation schemes that allow eliminating the chemical-shift dependence to a large extent over a predefined range. At the same time, the rate constants are maximized.

Wittmann, Johannes J.; Hendriks, Lyndsey; Meier, Beat H.; Ernst, Matthias

2014-07-01

369

Chemical control of single bubble cavitation  

NASA Astrophysics Data System (ADS)

Sonochemistry would be ideally studied with a single bubble with known size pulsating in known acoustic pressure field. Single bubble cavitation provides the means to make such studies. The promise that single bubble cavitation brought to the quantitative measurements of chemical activity of cavitation, however, has not been previously fulfilled due to the very small amount of reacting gas within a single bubble (typically <10-13 moles). We have now quantitated the chemical reactions inside a single cavitating bubble and established an inventory of energy dissipation during bubble collapse. The yields of nitrite ions, hydroxyl radicals, and photons from a single cavitation bubble have now been measured, and the first true measures of energy efficiencies during acoustic cavitation have been determined. The energy efficiency of the formation of hydroxyl radicals from single bubble is comparable to that in multibubble cavitation. The energy efficiency of light emission, however, is much higher for SBSL. The observed rate of nitrite formation is in good agreement with the calculated diffusion rate of nitrogen into the bubble. The temperatures reached during single bubble cavitation in liquids with significant vapor pressures will be substantially limited by the endothermic chemical reactions of the polyatomics inside the collapsing bubble.

Didenko, Yuri T.; Suslick, Kenneth S.

2003-04-01

370

Indistinguishable tunable single photons emitted by spin-flip Raman transitions in InGaAs quantum dots.  

PubMed

This Letter reports all-optically tunable and highly indistinguishable single Raman photons from a driven single quantum dot spin. The frequency, linewidth, and lifetime of the Raman photons are tunable by varying the driving field power and detuning. Under continuous-wave excitation, subnatural linewidth single photons from off-resonant Raman scattering show an indistinguishability of 0.98(3). Under ? pulse excitation, spin- and time-tagged Raman fluorescence photons show an almost vanishing multiphoton emission probability of 0.01(2) and a two-photon quantum interference visibility of 0.95(3). Lastly, Hong-Ou-Mandel interference is demonstrated between two single photons emitted from remote, independent quantum dots with an unprecedented visibility of 0.87(4). PMID:24476302

He, Yu; He, Yu-Ming; Wei, Y-J; Jiang, X; Chen, M-C; Xiong, F-L; Zhao, Y; Schneider, Christian; Kamp, Martin; Höfling, Sven; Lu, Chao-Yang; Pan, Jian-Wei

2013-12-01

371

Electric field control of spin-resolved edge states in graphene quantum nanorings  

NASA Astrophysics Data System (ADS)

The electric-field effect on the electronic and magnetic properties of triangular and hexagonal graphene quantum rings with zigzag edge termination is investigated by means of the single-band tight-binding Hamiltonian and the mean-field Hubbard model. It is shown how the electron and spin states in the nanoring structures can be manipulated by applying an electric field. We find different spin-depolarization behaviors with variation of electric field strength due to the dependence of spin densities on the shapes and edges of this kind of nanorings. In the case of triangular quantum rings, the magnetization on the inner and outer edges can be selectively tuned and the spin states depolarize gradually as the field strength is increased, while in the case of hexagonal nanorings, the transverse electric field reduces the magnetic moments on both inner and outer edges symmetrically and rapidly.

Farghadan, R.; Saffarzadeh, A.

2014-05-01

372

Electric field control of spin precession in KTaO3 field-effect transistor  

NASA Astrophysics Data System (ADS)

Field-effect transistors (FET) with KTaO3 single crystal channel were fabricated to study spin-orbit coupling effects on the gate-induced electron gas. By applying gate voltage via organic gate insulator parylene, an electron accumulation layer was successfully formed at the interface of KTaO3. By analyzing magnetoresistance associated with weak ntilocalization at low temperature, we find that the spin precession length is remarkably short in this system, in the 20-70 nm range [1]. The factors possibly leading to this remarkably short spin precession length are 1) heavy electron mass originating from d-bands, 2) strongly asymmetric potential well, and 3) strong spin-orbit coupling caused by 5d element, tantalum.[4pt] [1] H. Nakamura and T. Kimura, Phys. Rev. B, 80, 121308(R) (2009).

Nakamura, Hiroyuki; Kimura, Tsuyoshi

2010-03-01

373

Voltage-controlled spin selection in a magnetic resonant tunneling diode.  

PubMed

We have fabricated all II-VI semiconductor resonant tunneling diodes based on the (Zn,Mn,Be)Se material system, containing dilute magnetic material in the quantum well, and studied their current-voltage characteristics. When subjected to an external magnetic field the resulting spin splitting of the levels in the quantum well leads to a splitting of the transmission resonance into two separate peaks. This is interpreted as evidence of tunneling transport through spin polarized levels, and could be the first step towards a voltage controlled spin filter. PMID:12857209

Slobodskyy, A; Gould, C; Slobodskyy, T; Becker, C R; Schmidt, G; Molenkamp, L W

2003-06-20

374

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

SciTech Connect

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

Jing, H.; Jiang, Y. [Department of Physics, Henan Normal University, Xinxiang 453007 (China); Meystre, P. [B2 Institute and Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States)

2009-12-15

375

Electric control of spin-dependent Goos-Hänchen shift in a magnetically modulated semiconductor nanostructure  

NASA Astrophysics Data System (ADS)

We theoretically investigate how to manipulate spin-dependent Goos-Hänchen (GH) shifts by an applied bias in a realistic magnetic-barrier nanostructure, which is experimentally created by depositing a ferromagnetic stripe with perpendicular magnetization on the top of heterostructure. GH shifts of transmitted electron beams are calculated numerically with the help of the stationary phase method. It is shown that both magnitude and sign of spin polarization in GH shifts are closely relative to the applied bias, which can give rise to a bias-controllable spin beam splitter.

Kong, Yong-Hong; Fu, Xi; Chen, Sai-Yan; Li, Ai-Hua; Liang, Xiao-Lin

2013-11-01

376

Dynamical spin properties of exciton and biexciton in /CdMnTe/CdTe/CdMgTe single quantum well  

NASA Astrophysics Data System (ADS)

Exciton and biexciton optical properties in II-VI semiconductor single quantum well have been studied by magneto-photoluminescence, and time-resolved four-wave-mixing spectroscopies. The polarization dependence of both measurements can clearly distinguish biexciton from other bound states and show the dynamical spin properties of exciton and biexciton.

Adachi, S.; Tsuchiya, T.; Mino, H.; Takeyama, S.; Karczewski, G.; Wojitowicz, T.; Kossut, J.

2001-05-01

377

Next-to-Leading Order Calculation of the Single Transverse Spin Asymmetry in the Drell-Yan Process  

SciTech Connect

We calculate the next-to-leading order perturbative QCD corrections to the transverse momentum weighted single transverse spin asymmetry in Drell-Yan lepton pair production in hadronic collisions. We identify the splitting function relevant for the scale evolution of the twist-three quark-gluon correlation function. We comment on the consequences of our results for phenomenology.

Vogelsang, Werner; Yuan, Feng

2009-03-30

378

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

Microsoft Academic Search

We report single-shot measurements of resistance versus time for thermally assisted spin-torque switching in magnetic tunnel junctions. We achieve the sensitivity to resolve the magnetic dynamics prior to as well as during switching, yielding detailed views of switching modes and variations between events. Analyses of individual traces allow measurements of coherence times, nonequilibrium excitation spectra, and variations in magnetization precession

Y.-T. Cui; G. Finocchio; C. Wang; J. A. Katine; R. A. Buhrman; D. C. Ralph

2010-01-01

379

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

380

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

381

Electric-Field-Induced Spin Flop in BiFeO3 Single Crystals at Room Temperature  

Microsoft Academic Search

Bismuth ferrite, BiFeO3, is the only known room-temperature magnetic ferroelectric material. We demonstrate here, using neutron scattering measurements in high quality single crystals, that the antiferromagnetic and ferroelectric order parameters are intimately coupled. Initially in a single ferroelectric state, our crystals have a canted antiferromagnetic structure describing a unique cycloid. Under electrical poling, polarization reorientation induces a spin flop. We

D. Lebeugle; D. Colson; A. Forget; M. Viret; A. M. Bataille; A. Gukasov

2008-01-01

382

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

383

Transverse Spin Structure of the Nucleon through Target Single Spin Asymmetry in Semi-Inclusive Deep-Inelastic $(e,e^\\prime \\pi^\\pm)$ Reaction at Jefferson Lab  

SciTech Connect

Jefferson Lab (JLab) 12 GeV energy upgrade provides a golden opportunity to perform precision studies of the transverse spin and transverse-momentum-dependent structure in the valence quark region for both the proton and the neutron. In this paper, we focus our discussion on a recently approved experiment on the neutron as an example of the precision studies planned at JLab. The new experiment will perform precision measurements of target Single Spin Asymmetries (SSA) from semi-inclusive electro-production of charged pions from a 40-cm long transversely polarized $^3$He target in Deep-Inelastic-Scattering kinematics using 11 and 8.8 GeV electron beams. This new coincidence experiment in Hall A will employ a newly proposed solenoid spectrometer (SoLID). The large acceptance spectrometer and the high polarized luminosity will provide precise 4-D ($x$, $z$, $P_T$ and $Q^2$) data on the Collins, Sivers, and pretzelocity asymmetries for the neutron through the azimuthal angular dependence. The full 2$\\pi$ azimuthal angular coverage in the lab is essential in controlling the systematic uncertainties. The results from this experiment, when combined with the proton Collins asymmetry measurement and the Collins fragmentation function determined from the e$^+$e$^-$ collision data, will allow for a quark flavor separation in order to achieve a determination of the tensor charge of the d quark to a 10% accuracy. The extracted Sivers and pretzelocity asymmetries will provide important information to understand the correlations between the quark orbital angular momentum and the nucleon spin and between the quark spin and nucleon spin.

Gao, H; Chen, J -P; Qian, X; Qiang, Y; Huang, M; Afanasev, A; Anselmino, M; Avakian, H; Cates, G; Chudakov, E; Cisbani, E; de Jager, C; Garibaldi, F; Hu, B T; Jiang, X; Kumar, K S; Li, X M; Lu, H J; Meziani, Z -E; Ma, B -Q; Mao, Y J; Peng, J -C; Prokudin, A; Schlegel, M; Souder, P; Xiao, Z G; Ye, Y

2011-01-01

384

Quasi sliding mode controller for single phase PFC boost converter  

Microsoft Academic Search

In this paper, a quasi sliding mode controller is proposed to control single phase PFC boost converter. The outer voltage loop is PI control and the sliding mode control is used in the inner current loop. The designed quasi sliding mode controller has advantages such as robustness when there are large variations in line voltage and output load. Moreover, the

Yanping Jiao; Fang Lin Luo

2010-01-01

385

Instrumentation and control system for an F-15 stall/spin  

NASA Technical Reports Server (NTRS)

An instrumentation and control system is described that was used for radio-controlled F-15 airplane model stall/spin research at the NASA-Langley Research Center. This stall/spin research technique, using scale model aircraft, provides information on the post-stall and spin-entry characteristics of full-scale aircraft. The instrumentation described provides measurements of flight parameters such as angle of attack and sideslip, airspeed, control-surface position, and three-axis rotation rates; these data are recorded on an onboard magnetic tape recorder. The proportional radio control system, which utilizes analog potentiometric signals generated from ground-based pilot inputs, and the ground-based system used in the flight operation are also described.

Pitts, F. L.; Holmes, D. C. E.; Zaepfel, K. P.

1974-01-01

386

Robust control of entanglement in a nitrogen-vacancy center coupled to a C13 nuclear spin in diamond  

NASA Astrophysics Data System (ADS)

We address the problem of generating a robust entangling gate between electronic and nuclear spins in a system of a single nitrogen-vacancy center coupled to a nearest C13 atom in diamond against certain types of systematic errors such as pulse-length and off-resonance errors. We analyze the robustness of various control schemes: sequential pulses, composite pulses and numerically optimized pulses. We find that numerically optimized pulses, produced by the modified gradient ascent pulse engineering (GRAPE) algorithm, are more robust than the composite pulses and the sequential pulses. The optimized pulses can also be implemented in a faster time than the composite pulses.

Said, R. S.; Twamley, J.

2009-09-01

387

Controlled transport of superparamagnetic beads with spin-valves  

NASA Astrophysics Data System (ADS)

Trapping, release, and transport of individual, or ensembles of, 2.8 ?m superparamagnetic beads (SPB) functionalized with streptavidin were demonstrated with an addressable array of spin-valve (SV) traps integrated into a microfluidic channel. The linear array consists of two staggered lines of 1 ?m × 8 ?m SVs toggled ``on'' or ``off'' with 10 ms and 150 mA or -100 mA current pulses, respectively. The SPB is trapped when the SV is ``on'' and released or ignored when the SV is ``off''. This ``switchable permanent magnet'' offers a low power alternative to other precision microfluidic transport devices.

Altman, Wendy R.; Moreland, John; Russek, Stephen E.; Han, Bruce W.; Bright, Victor M.

2011-10-01

388

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

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

389

Electrically controlled spin polarization and selection in a topological insulator sandwiched between ferromagnetic electrodes  

NASA Astrophysics Data System (ADS)

We theoretically investigate the electrically controllable spin polarization and selective efficiency of the edge state Dirac electron in a two-dimensional topological insulator (TI) sandwiched between ferromagnetic (FM) electrodes by using the method of Keldysh nonequilibrium Green's function. A nearly full spin polarization of the topological edge state with giant inversion of ˜80% is observed, which is much higher than the value previously reported. Moreover, the selective efficiency for spin-up electrons under the modulation of the parallel configuration of FM electrodes has been demonstrated to be larger than 95% for the first time, while that for spin-down electrons in the antiparallel case is higher than 90% in a wide energy range, owing to the inter-edge spin tunneling induced backscattering and spin dephasing effect. The obtained results may provide a deeper understanding of the TI edge states and a valuable guidance to design spin switch and filter with high on-off speed and selective efficiency based on TIs.

Guo, Junji; Liao, Wenhu; Zhao, Heping; Zhou, Guanghui

2014-01-01

390

Giant Rotating Magnetocaloric Effect in the Region of Spin-Reorientation Transition in the NdCo5 Single Crystal  

NASA Astrophysics Data System (ADS)

We have investigated the anisotropy of the magnetocaloric effect in a NdCo5 single crystal in a wide range of temperatures, including the spin-reorientation temperature region. In the field ?0H=1.3T in the spin-reorientation region 250-310 K, we discovered a giant rotating magnetocaloric effect of ˜1.6K, caused by rotation of the magnetization vector. The calculations of the anisotropy magnetocaloric effect for the field ?0H=1.3T have been carried out.

Nikitin, S. A.; Skokov, K. P.; Koshkid'Ko, Yu. S.; Pastushenkov, Yu. G.; Ivanova, T. I.

2010-09-01

391

Gate-voltage control of spin interactions between electrons and nuclei in a semiconductor  

Microsoft Academic Search

Semiconductors are ubiquitous in device electronics, because their charge distributions can be conveniently manipulated with applied voltages to perform logic operations. Achieving a similar level of control over the spin degrees of freedom, either from electrons or nuclei, could provide intriguing prospects for information processing and fundamental solid-state physics issues. Here, we report procedures that carry out the controlled transfer

J. H. Smet; R. A. Deutschmann; F. Ertl; W. Wegscheider; G. Abstreiter; K. von Klitzing

2003-01-01

392

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

Microsoft Academic Search

The paramagnetic properties of size-controlled ink particles isolated from the ink sacs of Sepia officinalis were studied by electron spin resonance (ESR) spectroscopy. Both the size-controlled ink particles and synthetic melanins seemingly yielded similar ESR spectra consisting of a singlet with a slightly asymmetrical signal. However, the progressive microwave power saturation revealed a clear difference between their paramagnetic behaviors. In

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

2010-01-01

393

Pairwise control of exchange interaction between individual spins in a triple quantum dot  

NASA Astrophysics Data System (ADS)

The original spin qubit proposal [1] suggested a linear array of spins for quantum computations and the exchange interaction for 2 qubit operations. An essential component of the proposal was the ability to control pairwise the exchange interaction between neighbouring pairs of spins. In this work we experimentally demonstrate such a pairwise control of the exchange interaction between three spins localized in a triple quantum dot (TQD) device. The TQD potential was formed using electrostatic lateral split-gate technology on a GaAs/GaAlAs heterostructure with a high-mobility two-dimensional electron gas [2]. We employ fast pulsing technique based on the Landau-Zener-Stuckelberg (LZS) approach for creating and manipulating coherent superpositions of three spin quantum states [3]. We show that we are able to maintain coherence when increasing the exchange coupling of one spin with another while simultaneously decreasing its coupling with the third.[4pt] [1] D. Loss, and D.P. DiVincenzo, Phys. Rev. A57, 120-126 (1998).[0pt] [2] L. Gaudreau , et al., Appl. Phys. Lett. v.95, 193101 (2009). [0pt] [3] J.R. Petta, H. Lu, and A.C. Gossard, Science v.327, 669-672 (2010).

Granger, G.; Studenikin, Sergei; Aers, G.; Kam, A.; Zawadzki, P.; Gaudreau, L.; Wasilewski, R.; Pioro-Ladriere, M.; Sachrajda, A.

2012-02-01

394

Gate-controlled persistent spin helix state in (In,Ga)As quantum wells  

NASA Astrophysics Data System (ADS)

In layered semiconductors with spin-orbit interaction (SOI) a persistent spin helix (PSH) state with suppressed spin relaxation is expected if the strengths of the Rashba and Dresselhaus SOI terms, ? and ?, are equal. Here we demonstrate gate control and detection of the PSH in two-dimensional electron systems with strong SOI including terms cubic in momentum. We consider strain-free InGaAs/InAlAs quantum wells and first determine a ratio ?/??1 for nongated structures by measuring the spin-galvanic and circular photogalvanic effects. Upon gate tuning the Rashba SOI strength in a complementary magnetotransport experiment, we monitor the complete crossover from weak antilocalization via weak localization to weak antilocalization, where the emergence of weak localization reflects a PSH-type state. A corresponding numerical analysis reveals that such a PSH-type state indeed prevails even in presence of strong cubic SOI, however no longer at ?=?.

Kohda, M.; Lechner, V.; Kunihashi, Y.; Dollinger, T.; Olbrich, P.; Schönhuber, C.; Caspers, I.; Bel'kov, V. V.; Golub, L. E.; Weiss, D.; Richter, K.; Nitta, J.; Ganichev, S. D.

2012-08-01

395

Modified Pulsed-continuous arterial spin labeling for labeling of a single artery  

PubMed Central

Imaging the contribution of different arterial vessels to the blood supply of the brain can potentially guide the treatment of vascular disease and other disorders. Previously available only with catheter angiography, vessel selective labeling of arteries has now been demonstrated with pulsed and continuous arterial spin labeling (ASL) methods. Pulsed continuous labeling, which permits continuous labeling on standard scanner RF hardware, has been used to encode the contribution of different vessels to the blood supply of the brain. Vessel encoding requires a longer scan, a more complex reconstruction algorithm, and may be more sensitive to fluctuations in flow, however. Here a method is presented for single artery selective labeling in which a disc around the targeted vessel is labeled. Based on pulsed-continuous labeling, this method is achieved by rotating the directions of added in-plane gradients. Numerical simulations of the simplest strategy show good efficiency but poor suppression of labeling at large distances from the target vessel. Amplitude modulation of the rotating in-plane gradients results in better suppression of distant vessels. In-vivo results demonstrate highly selective labeling of individual vessels and a rapid falloff of the labeling with distance from the center of the labeling disc, in agreement with the simulations.

Dai, Weiying; Robson, Philip M.; Shankaranarayanan, Ajit; Alsop, David C.

2012-01-01

396

Optical Pumping and Electron Spin Resonance of Single 87Rb Atoms on Helium Nanodroplets  

NASA Astrophysics Data System (ADS)

Our recent development of electron spin resonance (ESR) spectroscopy on superfluid helium nanodroplets (HeN) provides a sensitive tool to investigate interactions between a surface located alkali-metal atom and an ESR silent species inside the droplet. Highest sensitivity is expected for alkali-metal atoms with large hyperfine coupling. We present hyperfine resolved ESR spectra of single 87Rb (hyperfine constant a_HFS = 3417 MHz) atoms isolated on HeN. In accordance with our previous work on 85Rb (AHFS= 1012 MHz) we find a droplet size dependent increase of AHFS between 400 and 450 ppm, due to the electronic perturbation by the helium environment. The process of optical pumping and of optical detection on HeN is investigated in detail in order to optimize the ESR signal. A simple model for optical pumping on HeN is presented, which agrees well with the experimental results. M. Koch, G. Auböck, C. Callegari, and W.E. Ernst, Phys. Rev. Lett. 103, 035302 (2009) A. Volk, J. Poms, M. Koch, and W.E. Ernst, J. Phys. Chem. A, in press

Koch, Markus; Poms, Johannes; Volk, Alexander; Ernst, Wolfgang E.

2011-06-01

397

Nuclear-spin-dependent coherent population trapping of single nitrogen-vacancy centers in diamond  

NASA Astrophysics Data System (ADS)

Coherent population trapping (CPT) provides a highly sensitive means for probing the energy-level structure of an atomic system. For a nitrogen-vacancy center in diamond, the CPT offers an alternative to the standard optically detected magnetic resonance method for measuring the hyperfine structure of the electronic ground states. We show that the nuclear-spin-dependent CPT measures directly the hyperfine splitting of these states due to the 14N nuclear spin. The CPT spectral response obtained in the presence of a strong microwave field, resonant or nearly resonant with a ground-state spin transition, maps out the dynamic Stark splitting induced by the coherent spin excitation.

Golter, D. Andrew; Dinyari, Khodadad N.; Wang, Hailin

2013-03-01

398

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

399

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

400

Controlling the exchange interaction using the spin-flip transition of antiferromagnetic spins in Ni81 Fe19 /?- Fe2 O3  

NASA Astrophysics Data System (ADS)

We report anisotropy, coercivity, and exchange bias in ferromagnetic Ni81Fe19 layers coupled to antiferromagnetic (AF) (0001), (112¯0) , and (110¯2)?-Fe2O3 layers. We show that AF spin configurations which permit spin-flop coupling give rise to a strong uniaxial anisotropy and hence a large coercivity, and that by annealing in magnetic fields parallel to specific directions in the AF we can control either coercivity or exchange bias. In particular, we show that a reversible temperature-induced spin reorientation in the AF can be used to control the exchange interaction.

Dho, Joonghoe; Leung, C. W.; Barber, Z. H.; Blamire, M. G.

2005-05-01

401

Single spin-torque vortex oscillator using combined bottom-up approach and e-beam lithography  

NASA Astrophysics Data System (ADS)

A combined bottom-up assembly of electrodeposited nanowires and electron beam lithography technique has been developed to investigate the spin transfer torque and microwave emission on specially designed nanowires containing a single Co/Cu/Co pseudo spin valve. Microwave signals have been obtained even at zero magnetic field. Interestingly, high frequency vs. magnetic field tunability was demonstrated, in the range 0.4-2 MHz/Oe, depending on the orientation of the applied magnetic field relative to the magnetic layers of the pseudo spin valve. The frequency values and the emitted signal frequency as a function of the external magnetic field are in good quantitative agreement with the analytical vortex model as well as with micromagnetic simulations.

Abreu Araujo, F.; Piraux, L.; Antohe, V. A.; Cros, V.; Gence, L.

2013-06-01

402

Simple modeling of dipolar coupled 7Li spins and stimulated-echo spectroscopy of single-crystalline ?-eucryptite  

NASA Astrophysics Data System (ADS)

Stimulated-echo spectroscopy has recently been applied to study the ultra-slow dynamics of nuclear spin-3/2 probes such as 7Li and 9Be in solids. Apart from the dominant first-order quadrupolar interaction in the present article also the impact of the homonuclear dipolar interactions is considered in a simple way: the time evolution of a dipole coupled pair of spins with I=3/2 is calculated in an approximation, which takes into account that the satellite transitions usually do not overlap. Explicit analytical expressions describing various aspects of a coupled quadrupolar pair subjected to a Jeener-Broekaert pulse sequence are derived. Extensions to larger spin systems are also briefly discussed. These results are compared with experimental data on a single-crystalline Li ion conductor.

Qi, F.; Diezemann, G.; Böhm, H.; Lambert, J.; Böhmer, R.

2004-08-01

403

Simple modeling of dipolar coupled 7Li spins and stimulated-echo spectroscopy of single-crystalline beta-eucryptite.  

PubMed

Stimulated-echo spectroscopy has recently been applied to study the ultra-slow dynamics of nuclear spin-3/2 probes such as 7Li and 9Be in solids. Apart from the dominant first-order quadrupolar interaction in the present article also the impact of the homonuclear dipolar interactions is considered in a simple way: the time evolution of a dipole coupled pair of spins with I = 3/2 is calculated in an approximation, which takes into account that the satellite transitions usually do not overlap. Explicit analytical expressions describing various aspects of a coupled quadrupolar pair subjected to a Jeener-Broekaert pulse sequence are derived. Extensions to larger spin systems are also briefly discussed. These results are compared with experimental data on a single-crystalline Li ion conductor. PMID:15261617

Qi, F; Diezemann, G; Böhm, H; Lambert, J; Böhmer, R

2004-08-01

404

Single lever power control for piston aircraft engines  

Microsoft Academic Search

Based on the success of gas turbine and automotive engine control system designs, a single lever power control (SLPC) model for aircraft piston engines has been developed utilizing fuzzy logic controllers. To permit development and refinement of the SLPC controllers, a propulsion simulation workbench has been developed for simulation of light aircraft piston engine applications. The objective of the workbench

Scott E. Ashton; Louis F. Godbout

1997-01-01

405

Nuclear spin effects in semiconductor quantum dots  

NASA Astrophysics Data System (ADS)

The interaction of an electronic spin with its nuclear environment, an issue known as the central spin problem, has been the subject of considerable attention due to its relevance for spin-based quantum computation using semiconductor quantum dots. Independent control of the nuclear spin bath using nuclear magnetic resonance techniques and dynamic nuclear polarization using the central spin itself offer unique possibilities for manipulating the nuclear bath with significant consequences for the coherence and controlled manipulation of the central spin. Here we review some of the recent optical and transport experiments that have explored this central spin problem using semiconductor quantum dots. We focus on the interaction between 104-106 nuclear spins and a spin of a single electron or valence-band hole. We also review the experimental techniques as well as the key theoretical ideas and the implications for quantum information science.

Chekhovich, E. A.; Makhonin, M. N.; Tartakovskii, A. I.; Yacoby, A.; Bluhm, H.; Nowack, K. C.; Vandersypen, L. M. K.

2013-06-01

406

Nuclear magnetic resonance linewidth and spin diffusion in {sup 29}Si isotopically controlled silicon  

SciTech Connect

A nuclear magnetic resonance (NMR) study was performed with n-type silicon single crystals containing {sup 29}Si isotope abundance f ranges from 1.2% to 99.2%. The nuclear spin diffusion coefficient D has been determined from the linewidth of significantly enhanced {sup 29}Si NMR signals utilizing a developed dynamic nuclear polarization (DNP) method. The {sup 29}Si NMR linewidth depends linearly on f, at least when f<10%, and approaches {proportional_to}f{sup 1/2} dependence when f>50%. The estimated {sup 29}Si nuclear spin diffusion time T{sub sd} between phosphorus atoms used for DNP is more than ten times shorter than the nuclear polarization time T{sub 1}{sup p} of {sup 29}Si nuclei around phosphorus. Therefore, the regime of 'rapid spin diffusion' is realized in the DNP experiments.

Hayashi, Hiroshi; Itoh, Kohei M.; Vlasenko, Leonid S. [Department of Applied Physics and Physico-Informatics, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); A. F. Ioffe Physico-Technical Institute, 194021 Saint Petersburg (Russian Federation)

2008-10-15

407

Probing spin entanglement by gate-voltage-controlled interference of current correlation in quantum spin Hall insulators  

NASA Astrophysics Data System (ADS)

We propose an entanglement detector composed of two quantum spin Hall insulators and a side gate deposited on one of the edge channels. For an ac gate voltage, the differential noise contributed from the entangled electron pairs exhibits the nontrivial step structures, from which the spin entanglement concurrence can be easily obtained. The possible spin dephasing effects in the quantum spin Hall insulators are also included.

Chen, Wei; Wang, Z. D.; Shen, R.; Xing, D. Y.

2014-05-01

408

Field Induced Spin-Flop Transition in a Na0.8CoO2 Single Crystal  

NASA Astrophysics Data System (ADS)

We measured the magnetization of a high-quality single crystal of Na0.8CoO2 prepared by the floating-zone method under magnetic fields along the c axis up to 12T. Magnetization measurements clearly show that a transition exists at an applied field of about 9T along the c axis below ~21K. This suggests that a spin flop transition occurs between an antiferromagnetic state and a spin polarized state (along the c direction) in a field of about 9T at low temperatures. The magnetization of the Na0.8CoO2 single crystal in applied magnetic fields can be described by the magnetic phase diagram for NaxCoO2 with x>=0.75.

Guo, Y. Q.; Huang, M.; Luo, J. L.; Wu, D.; Jin, D.

2006-09-01

409

Measurement of the Target Single-Spin Asymmetry in Quasi-Elastic ^3He^(e,e')  

NASA Astrophysics Data System (ADS)

Nuclear and nucleon structure are often studied by measuring form factors using the Born approximation, which assumes one-photon exchange, with multiple-photon exchanges neglected, so the target single-spin asymmetry is expected to be zero in the Born approximation. The Jefferson Lab experiment E05-015 was devoted to the measurement of the neutron target single-spin asymmetry, A^ny, using the inclusive quasi-elastic ^3He^(e,e') reaction with a vertically polarized ^3He target and standard Hall A high resolution spectrometers at Q^2=0.13, 0.46 and 0.97 (GeV/c)^2. The non-zero results from this experiment clearly demonstrate the contribution of two-photon exchange, providing new constraints on Generalized Parton Distribution Models and new information on the dynamics of the two-photon exchange process. Details of this experiment and a very preliminary result will be presented.

Zhang, Yawei

2011-04-01

410

Transverse single spin asymmetry in e+p??e+J/?+X and transverse momentum dependent evolution of the Sivers function  

NASA Astrophysics Data System (ADS)

We extend our analysis of transverse single spin asymmetry in electroproduction of J/? to include the effect of the scale evolution of the transverse momentum dependent (TMD) parton distribution functions and gluon Sivers function. We estimate single spin asymmetry for JLab, HERMES, COMPASS, and eRHIC energies using the color evaporation model of charmonium production, using an analytically obtained approximate solution of TMD evolution equations discussed in the literature. We find that there is a reduction in the asymmetry compared with our predictions for the earlier case considered by us, wherein the Q2 dependence came only from DGLAP evolution of the unpolarized gluon densities and a different parametrization of the TMD Sivers function was used.

Godbole, Rohini M.; Misra, Anuradha; Mukherjee, Asmita; Rawoot, Vaibhav S.

2013-07-01

411

Single-layer organic light-emitting diode with 2.0% external quantum efficiency prepared by spin-coating  

Microsoft Academic Search

We present a highly efficient organic light-emitting diode with a single-layer structure and air-stable Al cathode. The device consists of a spin-coated thin film of polystyrene in which rubrene and Alq3 molecules are dispersed. By optimizing the concentration of Alq3 and rubrene, a maximum external quantum efficiency of 2.0% photons\\/electron and a current efficiency of 8.5 cd\\/A at 22 V

Y. D. Jin; J. P. Yang; P. L. Heremans; M. Van der Auweraer; E. Rousseau; H. J. Geise; G. Borghs

2000-01-01

412

EPR study of Mn in ferroelastic BiVO4 single crystal: Monoclinic spin hamiltonian parameters and their temperature dependence  

Microsoft Academic Search

Zero-field splitting (ZFS) parameters of Mn in a BiVO4 single crystal obtained with a Q-band EPR spectrometer at room temperature are analyzed with the monoclinic spin Hamiltonian and compared with those of Baran et al. The ZFS Bk shows that the site symmetry of Mn (or Bi) center in the ferroelastic BiVO4 crystal is monoclinic. The temperature dependence of Mn

Tae Ho Yeom; Czeslaw Rudowicz; Sung Ho Choh

1994-01-01

413

Spin liquid in a single crystal of the frustrated diamond lattice antiferromagnet CoAl2O4  

Microsoft Academic Search

We study the evidence for spin liquid in the frustrated diamond lattice antiferromagnet CoAl2O4 by means of single-crystal neutron scattering in zero and applied magnetic fields. The magnetically ordered phase appearing below TN=8 K remains nonconventional down to 1.5 K. The magnetic Bragg peaks at the q=0 positions are broad and their line shapes have strong Lorentzian contributions. Additionally, the

O. Zaharko; N. B. Christensen; A. Cervellino; V. Tsurkan; A. Maljuk; U. Stuhr; C. Niedermayer; F. Yokaichiya; D. N. Argyriou; M. Boehm; A. Loidl

2011-01-01

414

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

415

Short-time scaling via Monte Carlo single spin-flip algorithms for the Baxter–Wu model  

Microsoft Academic Search

The short-time critical dynamics of the Baxter–Wu model is investigated via Monte Carlo simulations using single spin-flip algorithms. The critical dynamic exponents z and ? are estimated and it is shown that the N-fold way provides a reliable estimate for the ratio of the static exponents (2?\\/?) and a good confirmation of the short-time scheme. However, we find that the

I. A. Hadjiagapiou; A. Malakis; S. S. Martinos

2005-01-01

416

Electronically controllable biquads using single CDBA  

Microsoft Academic Search

Three new electronically tunable filter configurations which employ only one current controlled differencing buffered amplifier (CDBA) are proposed. The proposed filters operate in voltage-mode (VM) and use three passive elements. Each proposed filter can realize one of the band-pass, low-pass or high-pass responses. The parameters omega 0 and omega0\\/Q enjoy independent electronic tunability. Effect of the non-idealities and the sensitivity

Sükrü Eser Oner; Muhammet Koksal; Mehmet Sagbas

2006-01-01

417

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

418

Constrained Active Space Unrestricted Mean-Field Approaches for Controlling Spin-Contamination  

NASA Astrophysics Data System (ADS)

We have recently shown that unrestricted Hartree-Fock (UHF) variationally reduces to high-spin restricted open-shell Hartree-Fock when constraints are imposed on the eigenvalues of the spin density matrix [T. Tsuchimochi and G. E. Scuseria, J. Chem. Phys. 133, 141102 (2010)]. We here generalize these ideas and propose to control spin-contamination in UHF by releasing the constraints in an active space while imposing them elsewhere. If the active space is properly chosen, our constrained UHF (CUHF) method greatly benefits from a controlled broken-symmetry effect while avoiding the massive spin contamination arising in the traditional UHF. We apply Lowdin's projection operator to CUHF and obtain multireference wave functions with moderate computational cost. We report results on singlet-triplet energy gaps to show that our constrained scheme outperforms fully unrestricted methods. This constrained approach can be readily used in Kohn-Sham (KS) density functional theory with similar favorable effects, provided that spin-contamination is given by the KS orbitals as in UHF.

Tsuchimochi, Takashi; Scuseria, Gustavo E.

2011-03-01

419

Gate-voltage control of spin interactions between electrons and nuclei in a semiconductor.  

PubMed

Semiconductors are ubiquitous in device electronics, because their charge distributions can be conveniently manipulated with voltages to perform logic operations. Achieving a similar level of control over the spin degrees of freedom, either from electrons or nuclei, could provide intriguing prospects for both information processing and the study of fundamental solid-state physics issues. Here we report procedures that carry out the controlled transfer of spin angular momentum between electrons-confined to two dimensions and subjected to a perpendicular magnetic field-and the nuclei of the host semiconductor, using gate voltages only. We show that the spin transfer rate can be enhanced near a ferromagnetic ground state of the electron system, and that the induced nuclear spin polarization can be subsequently stored and 'read out'. These techniques can also be combined into a spectroscopic tool to detect the low-energy collective excitations in the electron system that promote the spin transfer. The existence of such excitations is contingent on appropriate electron-electron correlations, and these can be tuned by changing, for example, the electron density via a gate voltage. PMID:11796998

Smet, J H; Deutschmann, R A; Ertl, F; Wegscheider, W; Abstreiter, G; von Klitzing, K

2002-01-17

420

Intrinsic quantum noise in Faraday-rotation measurements of a single-electron spin  

NASA Astrophysics Data System (ADS)

Faraday rotation is one way to realize quantum nondemolition measurement of electron spin in quantum dots. To describe Faraday rotation, semiclassical models are typically used based on quantized electron-spin states and classical electromagnetic fields. Such treatments neglect the entanglement between electronic and photonic degrees of freedom that produce intrinsic quantum noise, limiting the ultimate sensitivity of this technique. We present a fully quantum-mechanical description of Faraday rotation and quantify this intrinsic noise. A method for measuring the purity of a given spin state is suggested based on this analysis.

Ma, Yanjun; Levy, Jeremy

2009-02-01

421

Local control of single atom magnetocrystalline anisotropy.  

PubMed

Individual Fe atoms on a Cu(2)N/Cu(100) surface exhibit strong magnetic