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1

Single-shot readout of a single nuclear spin.

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

2

Electrically driven nuclear spin resonance in single-molecule magnets.

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

3

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

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

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

2013-07-01

4

Nuclear magnetic resonance spectroscopy with single spin sensitivity

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

5

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

6

Distinguishing between Nonorthogonal Quantum States of a Single Nuclear Spin

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

7

NASA Astrophysics Data System (ADS)

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

Hildmann, Julia; Burkard, Guido

2014-09-01

8

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

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

2004-09-12

9

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

10

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

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

2012-06-22

11

TRANSVERSITY SINGLE SPIN ASYMMETRIES.

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

BOER,D.

2001-04-27

12

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

Morello, A; Millán, A; de Jongh, L J

2014-03-21

13

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

14

Single spin stochastic optical reconstruction microscopy

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

Pfender, Matthias; Waldherr, Gerald; Wrachtrup, Jörg

2014-01-01

15

Decoherence dynamics of a single spin versus spin ensemble

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

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

2008-06-26

16

Liquid-state nuclear spin comagnetometers.

We discuss nuclear spin comagnetometers based on ultralow-field nuclear magnetic resonance in mixtures of miscible solvents, each rich in a different nuclear spin. In one version thereof, Larmor precession of protons and 19F nuclei in a mixture of thermally polarized pentane and hexafluorobenzene is monitored via a sensitive alkali-vapor magnetometer. We realize transverse relaxation times in excess of 20 s and suppression of magnetic field fluctuations by a factor of 3400. We estimate it should be possible to achieve single-shot sensitivity of about 5×10(-9)??Hz, or about 5×10(-11)??Hz in ?1 day of integration. In a second version, spin precession of protons and 129Xe nuclei in a mixture of pentane and hyperpolarized liquid xenon is monitored using superconducting quantum interference devices. Application to spin-gravity experiments, electric dipole moment experiments, and sensitive gyroscopes is discussed. PMID:23004267

Ledbetter, M P; Pustelny, S; Budker, D; Romalis, M V; Blanchard, J W; Pines, A

2012-06-15

17

Nuclear moment of inertia and spin distribution of nuclear levels

We introduce a simple model to calculate the nuclear moment of inertia at finite temperature. This moment of inertia describes the spin distribution of nuclear levels in the framework of the spin-cutoff model. Our model is based on a deformed single-particle Hamiltonian with pairing interaction and takes into account fluctuations in the pairing gap. We derive a formula for the moment of inertia at finite temperature that generalizes the Belyaev formula for zero temperature. We show that a number-parity projection explains the strong odd-even effects observed in shell model Monte Carlo studies of the nuclear moment of inertia in the iron region.

Alhassid, Y.; Fang, L.; Liu, S. [Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06520 (United States); Bertsch, G.F. [Department of Physics and Institute of Nuclear Theory, Box 351560, University of Washington Seattle, Washington 98915 (United States)

2005-12-15

18

Single-spin stochastic optical reconstruction microscopy.

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

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

2014-10-14

19

Single spin stochastic optical reconstruction microscopy

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

Matthias Pfender; Nabeel Aslam; Gerald Waldherr; Jörg Wrachtrup

2014-04-05

20

Spin-Orbit Interaction of Nuclear Shell Structure

Single particle spin-orbit interaction energy problem in nuclear shell structure is solved through negative harmonic oscillator in the self-similar-structure shell model (SSM) [4] and considering quarks' contributions on single particle spin and orbit momentum. The paper demonstrates that single particle motion in normal nuclei is described better by SSM negative harmonic oscillator than conventional shell model positive harmonic oscillator[1][2][3]. The proposed theoretical formula for spin orbit interaction energy agrees well to experiment measurements.

Xiaobin Wang; Zhengda Wang; Xiaochun Wang; Xiaodong Zhang

2012-02-29

21

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

22

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

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

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

2014-01-01

23

Control of single spin in Markovian environment

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

Yuan, Haidong

24

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

25

NASA Technical Reports Server (NTRS)

Electron spin dephasing and decoherence by its interaction with nuclear spins in self-assembled quantum dots are investigated in the framework of the empirical tight-binding model. Electron spin dephasing in an ensemble of dots is induced by the inhomogeneous precession frequencies of the electron among dots, while electron spin decoherence in a single dot arises from the inhomogeneous precession frequencies of nuclear spins in the dot. For In(x)Ga(1-x) As self-assembled dots containing 30000 nuclei, the dephasing and decoherence times are predicted to be on the order of 100 ps and 1 (micro)s.

Lee, Seungwon; vonAllmen, Paul; Oyafuso, Fabiano; Klimeck, Gerhard; Whale, K. Birgitta

2004-01-01

26

Nuclear spin polarization dynamics are measured in optically pumped individual GaAs/AlGaAs interface quantum dots by detecting the time-dependence of the Overhauser shift in photoluminescence (PL) spectra. Long nuclear polarization decay times of ~ 1 minute have been found indicating inefficient nuclear spin diffusion from the GaAs dot into the surrounding AlGaAs matrix in externally applied magnetic field. A spin diffusion coefficient two orders lower than that previously found in bulk GaAs is deduced.

A. E. Nikolaenko; E. A. Chekhovich; M. N. Makhonin; I. W. Drouzas; A. B. Vankov; J. Skiba-Szymanska; M. S. Skolnick; P. Senellart; A. Lemaitre; A. I. Tartakovskii

2009-01-15

27

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

28

Single-shot readout of an electron spin in silicon

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

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

2010-03-13

29

Coherent properties of single rare-earth spin qubits

Rare-earth-doped crystals are excellent hardware for quantum storage of optical information. Additional functionality of these materials is added by their waveguiding properties allowing for on-chip photonic networks. However, detection and coherent properties of rare-earth single-spin qubits have not been demonstrated so far. Here, we present experimental results on high-fidelity optical initialization, effcient coherent manipulation, and optical readout of a single electron spin of Ce$^{3+}$ ion in a YAG crystal. Under dynamic decoupling, spin coherence lifetime reaches $T_2$=2 ms and is almost limited by the measured spin-lattice relaxation time $T_1$=3.8 ms. Strong hyperfine coupling to aluminium nuclear spins suggests that cerium electron spins can be exploited as an interface between photons and long-lived nuclear spin memory. Combined with high brightness of Ce$^{3+}$ emission and a possibility of creating photonic circuits out of the host material, this makes cerium spins an interesting option for integrated quantum photonics.

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

2014-05-20

30

Electrical control of single hole spins in nanowire quantum dots.

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

31

Single-shot readout of an electron spin in silicon

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

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

2010-01-01

32

Spin effects in single-electron transistors

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

Granger, Ghislain

2005-01-01

33

Single Spin Measurement Using Cellular Automata Techniques

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

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

2006-09-08

34

The nuclear quadrupole spin-lattice relaxation was studied in the range 4.2-300 K for single crystals of Bi{sub 4}Ge{sub 3}O{sub 12} doped with minor amounts (the tenth fractions of mol%) of paramagnetic atoms of Cr, Nd, and Gd. Unusual spin dynamic features were recently found for these crystals at room temperature: a dramatic (up to 8-fold) increase in the effective nuclear quadrupole spin-spin relaxation time T{sub 2}* occurred upon doping the pure Bi{sub 4}Ge{sub 3}O{sub 12} sample. Unlike T{sub 2}*, the effective spin-lattice relaxation time T{sub 1}* at room temperature differs insignificantly for both doped and pure samples. But at lower temperatures, the samples exhibit considerably different behavior of the spin-lattice relaxation with temperature, which is caused by different contributions to the relaxation process of the dopant paramagnetic atoms. The distinctive maximum in the temperature dependence of the spin-lattice relaxation time for the Nd-doped crystal is shown to result from the crystal electric field effects.

Orlov, V. G., E-mail: orlov@mbslab.kiae.ru; Sergeev, G. S. [Russian Research Center 'Kurchatov Institute' (Russian Federation); Asaji, Tetsuo [Nihon University, Department of Chemistry, College of Humanities and Sciences (Japan); Kravchenko, E. A. [Russian Academy of Sciences, Institute of General and Inorganic Chemistry (Russian Federation); Kargin, Yu. F. [Russian Academy of Sciences, State Institute of Metallurgy and Material Science (Russian Federation)

2010-02-15

35

Quantum control and nanoscale placement of single spins in diamond

NASA Astrophysics Data System (ADS)

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

Awschalom, David D.

2011-03-01

36

Resolution of Single Spin Flips of a Single Proton

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

37

Nuclear spin qubits in a trapped-ion quantum computer

Physical systems must fulfill a number of conditions to qualify as useful quantum bits (qubits) for quantum information processing, including ease of manipulation, long decoherence times, and high fidelity readout operations. Since these conditions are hard to satisfy with a single system, it may be necessary to combine different degrees of freedom. Here we discuss a possible system, based on electronic and nuclear spin degrees of freedom in trapped ions. The nuclear spin yields long decoherence times, while the electronic spin, in a magnetic field gradient, provides efficient manipulation, and the optical transitions of the ions assure a selective and efficient initialization and readout.

M. Feng; Y. Y. Xu; F. Zhou; D. Suter

2009-04-26

38

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

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

Otani, Yoshichika

39

Single-Spin Asymmetries and Transversity

NASA Astrophysics Data System (ADS)

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

Ratcliffe, Philip G.

2003-07-01

40

Single-Spin Asymmetries and Transversity

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

Ratcliffe, P G

2002-01-01

41

Polarization of nuclear spins by a cold nanoscale resonator

A cold nanoscale resonator coupled to a system of nuclear spins can induce spin relaxation. In the low-temperature limit where spin-lattice interactions are ''frozen out,'' spontaneous emission by nuclear spins into a resonant mechanical mode can become the dominant mechanism for cooling the spins to thermal equilibrium with their environment. We provide a theoretical framework for the study of resonator-induced cooling of nuclear spins in this low-temperature regime. Relaxation equations are derived from first principles, in the limit where energy donated by the spins to the resonator is quickly dissipated into the cold bath that damps it. A physical interpretation of the processes contributing to spin polarization is given. For a system of spins that have identical couplings to the resonator, the interaction Hamiltonian conserves spin angular momentum, and the resonator cannot relax the spins to thermal equilibrium unless this symmetry is broken by the spin Hamiltonian. The mechanism by which such a spin system becomes ''trapped'' away from thermal equilibrium can be visualized using a semiclassical model, which shows how an indirect spin-spin interaction arises from the coupling of multiple spins to one resonator. The internal spin Hamiltonian can affect the polarization process in two ways: (1) By modifying the structure of the spin-spin correlations in the energy eigenstates, and (2) by splitting the degeneracy within a manifold of energy eigenstates, so that zero-frequency off-diagonal terms in the density matrix are converted to oscillating coherences. Shifting the frequencies of these coherences sufficiently far from zero suppresses the development of resonator-induced correlations within the manifold during polarization from a totally disordered state. Modification of the spin-spin correlations by means of either mechanism affects the strength of the fluctuating spin dipole that drives the resonator. In the case where product states can be chosen as energy eigenstates, spontaneous emission from eigenstate populations into the resonant mode can be interpreted as independent emission by individual spins, and the spins relax exponentially to thermal equilibrium if the development of resonator-induced correlations is suppressed. When the spin Hamiltonian includes a significant contribution from the homonuclear dipolar coupling, the energy eigenstates entail a correlation specific to the coupling network. Simulations of dipole-dipole coupled systems of up to five spins suggest that these systems contain weakly emitting eigenstates that can trap a fraction of the population for time periods >>100/R{sub 0}, where R{sub 0} is the rate constant for resonator-enhanced spontaneous emission by a single spin 1/2. Much of the polarization, however, relaxes with rates comparable to R{sub 0}. A distribution of characteristic high-field chemical shifts tends to increase the relaxation rates of weakly emitting states, enabling transitions to states that can quickly relax to thermal equilibrium. The theoretical framework presented in this paper is illustrated with discussions of spin polarization in the contexts of force-detected nuclear-magnetic-resonance spectroscopy and magnetic-resonance force microscopy.

Butler, Mark C.; Weitekamp, Daniel P. [A. A. Noyes Laboratory of Chemical Physics, California Institute of Technology, MC 127-72, Pasadena, California 91125 (United States)

2011-12-15

42

Polarization of nuclear spins by a cold nanoscale resonator

NASA Astrophysics Data System (ADS)

A cold nanoscale resonator coupled to a system of nuclear spins can induce spin relaxation. In the low-temperature limit where spin-lattice interactions are “frozen out,” spontaneous emission by nuclear spins into a resonant mechanical mode can become the dominant mechanism for cooling the spins to thermal equilibrium with their environment. We provide a theoretical framework for the study of resonator-induced cooling of nuclear spins in this low-temperature regime. Relaxation equations are derived from first principles, in the limit where energy donated by the spins to the resonator is quickly dissipated into the cold bath that damps it. A physical interpretation of the processes contributing to spin polarization is given. For a system of spins that have identical couplings to the resonator, the interaction Hamiltonian conserves spin angular momentum, and the resonator cannot relax the spins to thermal equilibrium unless this symmetry is broken by the spin Hamiltonian. The mechanism by which such a spin system becomes “trapped” away from thermal equilibrium can be visualized using a semiclassical model, which shows how an indirect spin-spin interaction arises from the coupling of multiple spins to one resonator. The internal spin Hamiltonian can affect the polarization process in two ways: (1) By modifying the structure of the spin-spin correlations in the energy eigenstates, and (2) by splitting the degeneracy within a manifold of energy eigenstates, so that zero-frequency off-diagonal terms in the density matrix are converted to oscillating coherences. Shifting the frequencies of these coherences sufficiently far from zero suppresses the development of resonator-induced correlations within the manifold during polarization from a totally disordered state. Modification of the spin-spin correlations by means of either mechanism affects the strength of the fluctuating spin dipole that drives the resonator. In the case where product states can be chosen as energy eigenstates, spontaneous emission from eigenstate populations into the resonant mode can be interpreted as independent emission by individual spins, and the spins relax exponentially to thermal equilibrium if the development of resonator-induced correlations is suppressed. When the spin Hamiltonian includes a significant contribution from the homonuclear dipolar coupling, the energy eigenstates entail a correlation specific to the coupling network. Simulations of dipole-dipole coupled systems of up to five spins suggest that these systems contain weakly emitting eigenstates that can trap a fraction of the population for time periods ?100/R0, where R0 is the rate constant for resonator-enhanced spontaneous emission by a single spin 1/2. Much of the polarization, however, relaxes with rates comparable to R0. A distribution of characteristic high-field chemical shifts tends to increase the relaxation rates of weakly emitting states, enabling transitions to states that can quickly relax to thermal equilibrium. The theoretical framework presented in this paper is illustrated with discussions of spin polarization in the contexts of force-detected nuclear-magnetic-resonance spectroscopy and magnetic-resonance force microscopy.

Butler, Mark C.; Weitekamp, Daniel P.

2011-12-01

43

Conversion of Nuclear Spin Isomers of Ethylene

NASA Astrophysics Data System (ADS)

A theoretical model of the nuclear spin isomer conversion in C2H4 induced by the intramolecular spin-spin interaction between hydrogen nuclei has been developed. In the ground electronic state, C2H4 has four nuclear spin isomers in contrast to two isomers in the molecules studied so far in this field of research. At the gas pressure of 1 Torr, the rate of conversion between isomers with the nuclear spin symmetries B1u and B2u was found to be 5.2 - 10-4 s-1, which coincides within experimental uncertainties with the rate recently measured by Sun et al. ( Science 2005, 310, 1938 ). It was determined that at low gas pressures the conversion is induced mainly by the mixing of only one pair of rotational states. The calculated pressure dependence of the conversion rate predicts that conversion slows down with increasing pressure at pressures higher than 300 Torr.

Chapovsky, P. L.; Zhivonitko, V. V.; Koptyug, I. V.

2013-10-01

44

Single-Spin Asymmetries and Transversity in QCD

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

45

NASA Astrophysics Data System (ADS)

Using fast electron spin resonance spectroscopy of a single nitrogen-vacancy defect in diamond, we demonstrate real-time readout of the Overhauser field produced by its nuclear spin environment under ambient conditions. These measurements enable narrowing the Overhauser field distribution by postselection, corresponding to a conditional preparation of the nuclear spin bath. Correlations of the Overhauser field fluctuations are quantitatively inferred by analyzing the Allan deviation over consecutive measurements. This method allows us to extract the dynamics of weakly coupled nuclear spins of the reservoir.

Dréau, A.; Jamonneau, P.; Gazzano, O.; Kosen, S.; Roch, J.-F.; Maze, J. R.; Jacques, V.

2014-09-01

46

Neutron single target spin asymmetries in SIDIS

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

47

Nuclear spin conversion in diatomic molecules

A mechanism of the internal interaction in dimers that mixes different nuclear spin modifications has been proposed. It has been shown that the intramolecular current associated with transitions between electronic terms of different parities can generate different magnetic fields on nuclei, leading to transitions between spin modifications and to the corresponding changes in rotational states. In the framework of the known quantum relaxation process, this interaction initiates irreversible conversion of nuclear spin modifications. The estimated conversion rate for nitrogen at atmospheric pressure is quite high (10{sup -3}-10{sup -5} s{sup -1})

Il'ichev, L. V., E-mail: leonid@iae.nsk.su; Shalagin, A. M. [Russian Academy of Sciences, Institute of Automation and Electrometry, Siberian Branch (Russian Federation)] [Russian Academy of Sciences, Institute of Automation and Electrometry, Siberian Branch (Russian Federation)

2013-07-15

48

Dynamical decoupling design for identifying weakly coupled nuclear spins in a bath

NASA Astrophysics Data System (ADS)

Identifying weakly coupled nuclear spins around single electron spins is a key step toward implementing quantum information processing using coupled electron-nuclei spin systems or sensing like single-spin nuclear magnetic resonance detection using diamond defect spins. Dynamical decoupling control of the center electron spin with periodic pulse sequences [e.g., the Carre-Purcell-Meiboom-Gill (CPMG) sequence] has been successfully used to identify single nuclear spins and to resolve structure of nuclear spin clusters. Here, we design a type of pulse sequence by replacing the repetition unit (a single ? pulse) of the CPMG sequence with a group of nonuniformly spaced ? pulses. Using the nitrogen-vacancy center system in diamond, we theoretically demonstrate that the designed pulse sequence improves the resolution of nuclear spin noise spectroscopy, and more information about the surrounding nuclear spins is extracted. The principle of dynamical decoupling design proposed in this paper is useful in many systems (e.g., defect spin qubit in solids, trapped ion, and superconducting qubit) for high-resolution noise spectroscopy.

Zhao, Nan; Wrachtrup, Jörg; Liu, Ren-Bao

2014-09-01

49

Spin quantum jumps in a singly charged quantum dot

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

50

Target Single Spin Asymmetry in DVCS

NASA Astrophysics Data System (ADS)

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

Seder, Erin

2011-10-01

51

Collins Mechanism Contributions to Single Spin Asymmetry

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

52

Collins Mechanism Contributions to Single Spin Asymmetry

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

53

Collins Mechanism Contributions to Single Spin Asymmetry

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

54

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

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

Walsworth, Ronald L.

55

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

NASA Astrophysics Data System (ADS)

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

Berezovsky, Jesse

2008-03-01

56

Decoherence of nuclear spin quantum memory in a quantum dot

Recently, an ensemble of nuclear spins in a quantum dot have been proposed as a long-lived quantum memory. A quantum state of an electron spin in the dot can be faithfully transfered into nuclear spins through controlled hyperfine coupling. Here we study the decoherence of this memory due to nuclear spin dipolar coupling and inhomogeneous hyperfine interaction during the storage

Changxue Deng; Xuedong Hu

2005-01-01

57

Phenomenological study of decoherence in solid-state spin qubits due to nuclear spin diffusion

NASA Astrophysics Data System (ADS)

We present a study of the prospects for coherence preservation in solid-state spin qubits using dynamical decoupling protocols. Recent experiments have provided the first demonstrations of multipulse dynamical decoupling sequences in this qubit system, but quantitative analyses of potential coherence improvements have been hampered by a lack of concrete knowledge of the relevant noise processes. We present calculations of qubit coherence under the application of arbitrary dynamical decoupling pulse sequences based on an experimentally validated semiclassical model. This phenomenological approach bundles the details of underlying noise processes into a single experimentally relevant noise power spectral density. Our results show that the dominant features of experimental measurements in a two-electron singlet-triplet spin qubit can be replicated using a 1/?2 noise power spectrum associated with nuclear spin flips in the host material. Beginning with this validation, we address the effects of nuclear programming, high-frequency nuclear spin dynamics, and other high-frequency classical noise sources, with conjectures supported by physical arguments and microscopic calculations where relevant. Our results provide expected performance bounds and identify diagnostic metrics that can be measured experimentally in order to better elucidate the underlying nuclear spin dynamics.

Biercuk, Michael J.; Bluhm, Hendrik

2011-06-01

58

NASA Astrophysics Data System (ADS)

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

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

2010-01-01

59

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

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

Loss, Daniel

60

Optical switching of nuclear spin-spin couplings in semiconductors

Two-qubit operation is an essential part of quantum computation. However, solid-state nuclear magnetic resonance quantum computing has not been able to fully implement this functionality, because it requires a switchable inter-qubit coupling that controls the time evolutions of entanglements. Nuclear dipolar coupling is beneficial in that it is present whenever nuclear–spin qubits are close to each other, while it complicates two-qubit operation because the qubits must remain decoupled to prevent unwanted couplings. Here we introduce optically controllable internuclear coupling in semiconductors. The coupling strength can be adjusted externally through light power and even allows on/off switching. This feature provides a simple way of switching inter-qubit couplings in semiconductor-based quantum computers. In addition, its long reach compared with nuclear dipolar couplings allows a variety of options for arranging qubits, as they need not be next to each other to secure couplings. PMID:21730962

Goto, Atsushi; Ohki, Shinobu; Hashi, Kenjiro; Shimizu, Tadashi

2011-01-01

61

Single transverse spin asymmetry of forward neutrons

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

62

Radio Frequency Scanning Tunneling Spectroscopy for Single-Molecule Spin Resonance

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

63

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

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

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

2014-09-26

64

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

65

Phosphorus-doped silicon single crystals with 0.19 % <= f <= 99.2 %, where f is the concentration of 29^Si isotopes, are measured at 8 K using a pulsed electron spin resonance technique, thereby the effect of environmental 29^Si nuclear spins on the donor electron spin is systematically studied. The linewidth as a function of f shows a good agreement with theoretical analysis. We also report the phase memory time T_M of the donor electron spin dependent on both f and the crystal axis relative to the external magnetic field.

Eisuke Abe; Akira Fujimoto; Junichi Isoya; Satoshi Yamasaki; Kohei M. Itoh

2005-12-16

66

Single Spin Asymmetry in Charmonium Production

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

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

2014-01-01

67

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

68

Ensemble spin coherence of singly charged InGaAs quantum dots

NASA Astrophysics Data System (ADS)

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

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

69

Spin-dependent quantum interference within a single magnetic nanostructure.

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

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

2010-02-12

70

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

NASA Astrophysics Data System (ADS)

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

Golter, D. Andrew; Wang, Hailin

2014-03-01

71

Ultrafast entangling gates between nuclear spins using photo-excited triplet states

The representation of information within the spins of electrons and nuclei has been powerful in the ongoing development of quantum computers. Although nuclear spins are advantageous as quantum bits (qubits) due to their long coherence lifetimes (exceeding seconds), they exhibit very slow spin interactions and have weak polarisation. A coupled electron spin can be used to polarise the nuclear spin and create fast single-qubit gates, however, the permanent presence of electron spins is a source of nuclear decoherence. Here we show how a transient electron spin, arising from the optically excited triplet state of C60, can be used to hyperpolarise, manipulate and measure two nearby nuclear spins. Implementing a scheme which uses the spinor nature of the electron, we performed an entangling gate in hundreds of nanoseconds: five orders of magnitude faster than the liquid-state J coupling. This approach can be widely applied to systems comprising an electron spin coupled to multiple nuclear spins, such as NV centres, while the successful use of a transient electron spin motivates the design of new molecules able to exploit photo-excited triplet states.

Vasileia Filidou; Stephanie Simmons; Steven D. Karlen; Feliciano Giustino; Harry L. Anderson; John J. L. Morton

2012-01-23

72

NUCLEAR SPIN ISOSPIN RESPONSES FOR LOW-ENERGY NEUTRINOS

NUCLEAR SPIN ISOSPIN RESPONSES FOR LOW-ENERGY NEUTRINOS Hiroyasu EJIRI Nuclear Physics Laboratory@rcnp.osaka-u.ac.jp (H. Ejiri). Physics Reports 338 (2000) 265}351 Nuclear spin isospin responses for low-energy Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka, 567 Japan. E-mail address: ejiri

Washington at Seattle, University of

73

Electronic transport through nuclear-spin-polarization-induced quantum wire

Electron transport in a new low-dimensional structure - the nuclear spin polarization induced quantum wire (NSPI QW) is theoretically studied. In the proposed system the local nuclear spin polarization creates the effective hyperfine field which confines the electrons with the spins opposite to the hyperfine field to the regions of maximal nuclear spin polarization. The influence of the nuclear spin relaxation and diffusion on the electron energy spectrum and on the conductance of the quantum wire is calculated and the experimental feasibility is discussed.

Yu. V. Pershin; S. N. Shevchenko; I. D. Vagner; P. Wyder

2001-09-25

74

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

Chunyang Tang; Xin Hu; Xinyu Pan

2010-09-08

75

Spin phase coherence of donor nuclear spins in silicon: the influence of electrical readout

NASA Astrophysics Data System (ADS)

Storing information in spin underpins the operation of a wide range of emerging technologies. However, the ability to interact with, and thus control electron spin implies a reasonable coupling to the environment, and a correspondingly limited spin coherence time. This problem can be overcome by using nuclear spins for long term information storage, and significant experimental progress in this direction has been seen recently. Readout of stored information can be achieved in a variety of ways, with electrical approaches offering substantial benefit with regard to integration of spintronic and classical electronic applications. Here, we discuss electrical readout of coherent nuclear spin states of donor nuclei in silicon. By utilizing nuclear Hahn echo sequences, we are able to demonstrate that nuclear spin phase coherence can exceed 3 ms with electrical readout. We find that the spin phase coherence is in this case limited by the spin lifetime of the donor electron which mediates our readout scheme, and discuss approaches to ameliorate this effect.

McCamey, Dane; van Tol, Johan; Morley, Gavin; Boehme, Christoph

2012-02-01

76

Dynamic Nuclear Spin Resonance in n-GaAs

NASA Astrophysics Data System (ADS)

The dynamics of optically detected nuclear magnetic resonance is studied in n-GaAs via time-resolved Kerr rotation using an on-chip microcoil for rf field generation. Both optically allowed and optically forbidden NMR are observed with a dynamics controlled by the interplay between dynamic nuclear polarization via hyperfine interaction with optically generated spin-polarized electrons and nuclear spin depolarization due to magnetic resonance absorption. Comparing the characteristic nuclear spin relaxation rate obtained in experiment with master equation simulations, the underlying nuclear spin depolarization mechanism for each resonance is extracted.

Chen, Y. S.; Reuter, D.; Wieck, A. D.; Bacher, G.

2011-10-01

77

Dynamic nuclear spin resonance in n-GaAs.

The dynamics of optically detected nuclear magnetic resonance is studied in n-GaAs via time-resolved Kerr rotation using an on-chip microcoil for rf field generation. Both optically allowed and optically forbidden NMR are observed with a dynamics controlled by the interplay between dynamic nuclear polarization via hyperfine interaction with optically generated spin-polarized electrons and nuclear spin depolarization due to magnetic resonance absorption. Comparing the characteristic nuclear spin relaxation rate obtained in experiment with master equation simulations, the underlying nuclear spin depolarization mechanism for each resonance is extracted. PMID:22107431

Chen, Y S; Reuter, D; Wieck, A D; Bacher, G

2011-10-14

78

A method for nuclear spin statistics in molecular spectroscopy

Using spin projection operator methods, generating functions are developed for nuclear spin species. These operators also generate elegantly the irreducible respresentations spanned by a1b1a2b2???atbt nuclear spin functions, where ai is the number of possible spin states of the bi nuclei of the same kind in the molecule. From these generating functions the statistical weights of the rovibronic levels of any

K. Balasubramanian

1981-01-01

79

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

NASA Astrophysics Data System (ADS)

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

Mikkelsen, Maiken H.

2009-03-01

80

Adiabatic refocusing of nuclear spins in Tm3+:YAG

We show that the optical absorbance detection of nuclear spin echo gives direct access to the spin concentration, unlike most coherent signal detection techniques where the signal intensity/amplitude is difficult to connect experimentally with the spin concentration. This way we measure the spin refocusing efficiency in a crystal of Tm$^{3+}$:YAG. Given the large inhomogeneous broadening of the spin transition in this material, rephasing the spins with the usual hard pulse procedure would require excessively high radiofrequency power. Instead we resort to an adiabatic pulse sequence that perfectly returns the spins to their initial common orientation, at low power cost.

Lauro, R; Gouet, J -L Le

2010-01-01

81

Adiabatic refocusing of nuclear spins in Tm3+:YAG

We show that the optical absorbance detection of nuclear spin echo gives direct access to the spin concentration, unlike most coherent signal detection techniques where the signal intensity/amplitude is difficult to connect experimentally with the spin concentration. This way we measure the spin refocusing efficiency in a crystal of Tm$^{3+}$:YAG. Given the large inhomogeneous broadening of the spin transition in this material, rephasing the spins with the usual hard pulse procedure would require excessively high radiofrequency power. Instead we resort to an adiabatic pulse sequence that perfectly returns the spins to their initial common orientation, at low power cost.

R. Lauro; T. Chaneliere; J. -L. Le Gouet

2010-09-22

82

Adiabatic refocusing of nuclear spins in Tm3+:YAG

NASA Astrophysics Data System (ADS)

We show that the optical absorbance detection of nuclear spin echo gives direct access to the spin concentration, unlike most coherent signal detection techniques where the signal intensity/amplitude is difficult to connect experimentally with the spin concentration. This way we measure the spin-refocusing efficiency in a crystal of Tm3+:YAG. Given the large inhomogeneous broadening of the spin transition in this material, rephasing the spins with the usual hard pulse procedure would require excessively high radiofrequency power. Instead we resort to an adiabatic pulse sequence that perfectly returns the spins to their initial common orientation, at low power cost.

Lauro, R.; Chanelière, T.; Le Gouët, J.-L.

2011-01-01

83

Technical Notes Single-Sensor Identification of Spinning

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

Huang, Xun

84

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

85

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

Using the non-equilibrium Green's function (NEGF) formalism within the sequential regime, we studied ultrahigh spin thermopower and pure spin current in single-molecule magnet(SMM), which is attached to nonmagnetic metal wires with spin bias and angle (?) between the easy axis of SMM and the spin orientation in the electrodes. A pure spin current can be generated by tuning the gate voltage and temperature difference with finite spin bias and the arbitrary angle except of ?=1/2?, 2/3?. In the linear regime, large thermopower can be obtained by modifying V(g) and the angles (?). These results are useful in fabricating and advantaging SMM devices based on spin caloritronics. PMID:24549224

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

2014-01-01

86

NASA Astrophysics Data System (ADS)

Single electron or hole spins in III-V semiconductor quantum dots (QDs) are promising candidates for solid-state qubits. Their coherence properties are typically governed by the hyperfine coupling between these ``central'' electronic spins and the dense surrounding bath of lattice nuclear spins. Theoretically this is a challenging problem due to its many-body and strongly-correlated nature. Here we measure the spin dynamics of holes in InGaAs quantum dots by detecting their intrinsic, random spin fluctuations while in thermal equilibrium, which reveals the spin correlation time scales ?h and the functional form of bath-induced spin relaxation. In zero magnetic field, ?h is very long (˜400 ns) and decays exponentially, in marked contrast with recent theories. ?h increases to ˜5 ?s in small (100 G) longitudinal fields, and the spin dynamics evolve to a very slow ˜1/ln(t) decay [1]. We model the influence of nuclear quadrupolar coupling on spin dynamics in these strained QDs for both electrons and holes [2], and find a good agreement with experimental data when the quadrupolar coupling exceeds the hyperfine coupling strength. [1] Yan Li, N. Sinitsyn, et al., PRL 108, 186603 (2012). [2] N. Sinitsyn, Yan Li, et al., PRL 109, 166605 (2012).

Li, Yan; Sinitsyn, N. A.; Saxena, A.; Smith, D. L.; Reuter, D.; Wieck, A. D.; Yakovlev, D. R.; Manfred, B.; Crooker, S. A.

2013-03-01

87

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

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

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

2009-05-29

88

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

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

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

2013-01-01

89

Dependence of nuclear spin singlet lifetimes on RF spin-locking power Stephen J. DeVience a,

Dependence of nuclear spin singlet lifetimes on RF spin-locking power Stephen J. DeVience a: Received 6 January 2012 Revised 14 March 2012 Available online 28 March 2012 Keywords: Nuclear singlet of long-lived nuclear spin singlet states as a function of the strength of the RF spin-locking field

Rosen, Matthew S

90

Mode locking of electron spin coherence in singly charged quantum dots

NASA Astrophysics Data System (ADS)

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

Efros, Alexander

2008-10-01

91

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

Shin, Chang-Seok

2009-05-15

92

Squeezing and entangling nuclear spins in helium 3

We present a realistic model for transferring the squeezing or the entanglement of optical field modes to the collective ground state nuclear spin of $^3$He using metastability exchange collisions. We discuss in detail the requirements for obtaining good quantum state transfer efficiency and study the possibility to readout the nuclear spin state optically.

Gael Reinaudi; Alice Sinatra; Aurelien Dantan; Michel Pinard

2005-12-21

93

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

Many-body correlations can yield key insights into the nature of interacting systems; however, detecting them is often very challenging in many-particle physics, especially in nanoscale systems. Here, taking a phosphorus donor electron spin in a natural-abundance 29Si nuclear spin bath as our model system, we discover both theoretically and experimentally that many-body correlations in nanoscale nuclear spin baths produce identifiable signatures in the decoherence of the central spin under multiple-pulse dynamical decoupling control. We find that when the number of decoupling -pulses is odd, central spin decoherence is primarily driven by second-order nuclear spin correlations (pairwise flip-flop processes). In contrast, when the number of -pulses is even, fourth-order nuclear spin correlations (diagonal interaction renormalized pairwise flip-flop processes) are principally responsible for the central spin decoherence. Many-body correlations of different orders can thus be selectively detected by central spin decoherence under different dynamical decoupling controls, providing a useful approach to probing many-body processes in nanoscale nuclear spin baths.

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

2014-04-10

94

Protection of centre spin coherence by dynamic nuclear spin polarization in diamond.

We experimentally investigate the protection of electron spin coherence of a nitrogen-vacancy (NV) centre in diamond by dynamic nuclear spin polarization (DNP). The electron spin decoherence of an NV centre is caused by the magnetic field fluctuation of the (13)C nuclear spin bath, which contributes large thermal fluctuation to the centre electron spin when it is in an equilibrium state at room temperature. To address this issue, we continuously transfer the angular momentum from electron spin to nuclear spins, and pump the nuclear spin bath to a polarized state under the Hartmann-Hahn condition. The bath polarization effect is verified by the observation of prolongation of the electron spin coherence time (T). Optimal conditions for the DNP process, including the pumping pulse duration and repeat numbers, are proposed by numerical simulation and confirmed by experiment. We also studied the depolarization effect of laser pulses. Our results provide a new route for quantum information processing and quantum simulation using the polarized nuclear spin bath. PMID:25042514

Liu, Gang-Qin; Jiang, Qian-Qing; Chang, Yan-Chun; Liu, Dong-Qi; Li, Wu-Xia; Gu, Chang-Zhi; Po, Hoi Chun; Zhang, Wen-Xian; Zhao, Nan; Pan, Xin-Yu

2014-09-01

95

Nuclear spin diffusion effects in optically pumped quantum wells

NASA Astrophysics Data System (ADS)

We studied the influence of the nuclear spin diffusion on the dynamical nuclear polarization of low dimensional nanostructures subject to optical pumping. Our analysis shows that the induced nuclear spin polarization in semiconductor nanostructures will develop both a time and position dependence due to a nonuniform hyperfine interaction as a result of the geometrical confinement provided by the system. In particular, for the case of semiconductor quantum wells, nuclear spin diffusion is responsible for a nonzero nuclear spin polarization in the quantum well barriers. As an example we considered a 57 Å GaAs square quantum well and a 1000 Å AlxGa1-xAs parabolic quantum well both within 500 Å Al0.4Ga0.6As barriers. We found that the average nuclear spin polarization in the quantum well barriers depends on the strength of the geometrical confinement provided by the structure and is characterized by a saturation time of the order of few hundred seconds. Depending on the value of the nuclear spin diffusion constant, the average nuclear spin polarization in the quantum well barriers can get as high as 70% for the square quantum well and 40% for the parabolic quantum well. These results should be relevant for both time resolved Faraday rotation and optical nuclear magnetic resonance experimental techniques.

Henriksen, Daniel; Kim, Tom; ?ifrea, Ionel

2014-01-01

96

Preparation of Nuclear Spin Singlet States Using Spin-Lock Induced Crossing

NASA Astrophysics Data System (ADS)

We introduce a broadly applicable technique to create nuclear spin singlet states in organic molecules and other many-atom systems. We employ a novel pulse sequence to produce a spin-lock induced crossing (SLIC) of the spin singlet and triplet energy levels, which enables triplet-singlet polarization transfer and singlet-state preparation. We demonstrate the utility of the SLIC method by producing a long-lived nuclear spin singlet state on two strongly coupled proton pairs in the tripeptide molecule phenylalanine-glycine-glycine dissolved in D2O and by using SLIC to measure the J couplings, chemical shift differences, and singlet lifetimes of the proton pairs. We show that SLIC is more efficient at creating nearly equivalent nuclear spin singlet states than previous pulse sequence techniques, especially when triplet-singlet polarization transfer occurs on the same time scale as spin-lattice relaxation.

DeVience, Stephen J.; Walsworth, Ronald L.; Rosen, Matthew S.

2013-10-01

97

Preparation of Nuclear Spin Singlet States using Spin-Lock Induced Crossing

We introduce a broadly applicable technique to create nuclear spin singlet states in organic molecules and other many-atom systems. We employ a novel pulse sequence to produce a spin-lock induced crossing (SLIC) of the spin singlet and triplet energy levels, which enables triplet/singlet polarization transfer and singlet state preparation. We demonstrate the utility of the SLIC method by producing a long-lived nuclear spin singlet state on two strongly-coupled proton pairs in the tripeptide molecule phenylalanine-glycine-glycine dissolved in D2O, and by using SLIC to measure the J-couplings, chemical shift differences, and singlet lifetimes of the proton pairs. We show that SLIC is more efficient at creating nearly-equivalent nuclear spin singlet states than previous pulse sequence techniques, especially when triplet/singlet polarization transfer occurs on the same timescale as spin-lattice relaxation.

DeVience, Stephen J; Rosen, Matthew S

2013-01-01

98

Room temperature hyperpolarization of nuclear spins in bulk.

Dynamic nuclear polarization (DNP), a means of transferring spin polarization from electrons to nuclei, can enhance the nuclear spin polarization (hence the NMR sensitivity) in bulk materials at most 660 times for (1)H spins, using electron spins in thermal equilibrium as polarizing agents. By using electron spins in photo-excited triplet states instead, DNP can overcome the above limit. We demonstrate a (1)H spin polarization of 34%, which gives an enhancement factor of 250,000 in 0.40 T, while maintaining a bulk sample (? 0.6 mg, ? 0.7 × 0.7 × 1 mm(3)) containing >10(19) (1)H spins at room temperature. Room temperature hyperpolarization achieved with DNP using photo-excited triplet electrons has potentials to be applied to a wide range of fields, including NMR spectroscopy and MRI as well as fundamental physics. PMID:24821773

Tateishi, Kenichiro; Negoro, Makoto; Nishida, Shinsuke; Kagawa, Akinori; Morita, Yasushi; Kitagawa, Masahiro

2014-05-27

99

Cryogenic single-chip electron spin resonance detector

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

100

Colour Modification of Factorisation in Single-Spin Asymmetries

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

Ratcliffe, Philip G

2009-01-01

101

NASA Astrophysics Data System (ADS)

We describe a regime for low-field magnetoresistance in organic semiconductors, in which the spin-relaxing effects of localized nuclear spins and electronic spins interfere. The regime is studied by the controlled addition of localized electronic spins to a material that exhibits substantial room-temperature magnetoresistance (˜20%). Although initially the magnetoresistance is suppressed by the doping, at intermediate doping there is a regime where the magnetoresistance is insensitive to the doping level. For much greater doping concentrations the magnetoresistance is fully suppressed. The behavior is described within a theoretical model describing the effect of carrier spin dynamics on the current.

Wang, Y.; Harmon, N. J.; Sahin-Tiras, K.; Wohlgenannt, M.; Flatté, M. E.

2014-08-01

102

Nanomagnetism: Spin doctors play with single electrons

NASA Astrophysics Data System (ADS)

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

Erwin, Steven C.

2006-11-01

103

Single electron-spin memory with a semiconductor quantum dot

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

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

2007-06-14

104

A method for nuclear spin statistics in molecular spectroscopy

NASA Astrophysics Data System (ADS)

Using spin projection operator methods, generating functions are developed for nuclear spin species. These operators also generate elegantly the irreducible respresentations spanned by a1b1 a2b2???atbt nuclear spin functions, where ai is the number of possible spin states of the bi nuclei of the same kind in the molecule. From these generating functions the statistical weights of the rovibronic levels of any polyatomic molecule can be obtained easily. The method is illustrated with 33SF6, 13C-triphenylene, and triphenylene with protons replaced by D. For 13C-triphenylene there are 1 073 741 824 nuclear spin functions from which we determined the statistical weights of the rovibronic levels A'1, A'2, E', A?1, A?2, and E? to be 178 940 928, 178 973 696, 357 913 600, 178 940 928, 178 973 696, and 357 913 600, respectively.

Balasubramanian, K.

1981-06-01

105

Pulsed Nuclear Magnetic Resonance: Spin Echoes MIT Department of Physics

Pulsed Nuclear Magnetic Resonance: Spin Echoes MIT Department of Physics (Dated: February 5, 2014) In this experiment, the phenomenon of Nuclear Magnetic Resonance (NMR) is used to determine the magnetic moments-factor in atomic spectroscopy and is given by g = (Âµ/ÂµN )/I, (2) and ÂµN is the nuclear magneton, e /2mp

Seager, Sara

106

Spin-current autocorrelations from single pure-state propagation.

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

107

Factorisation in Higher-Twist Single-Spin Amplitudes

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

Ratcliffe, P G

1999-01-01

108

Phase-sensitive probes of nuclear polarization in spin-blockaded transport

Spin-blockaded quantum dots provide a unique setting for studying nuclear-spin dynamics in a nanoscale system. Despite recent experimental progress, observing phase-sensitive phenomena in nuclear spin dynamics remains ...

Levitov, Leonid

109

Electron spin dephasing and optical pumping of nuclear spins in GaN

NASA Astrophysics Data System (ADS)

We have measured the donor-bound electron spin dynamics in cubic GaN by time-resolved Kerr rotation experiments. The ensemble electron spin dephasing time in this quantum-dot-like system characterized by a Bohr radius of 2.5 nm is of the order of 1.5 ns as a result of the interaction with the fluctuating nuclear spins. It increases drastically when an external magnetic field as small as 10 mT is applied. We extract a dispersion of the nuclear hyperfine field ?Bn˜4mT , in agreement with calculations. We also demonstrate for the first time in GaN-based systems the optical pumping of nuclear spin yielding the buildup of a significant nuclear polarization.

Wang, G.; Zhu, C. R.; Liu, B. L.; Ye, H.; Balocchi, A.; Amand, T.; Urbaszek, B.; Yang, H.; Marie, X.

2014-09-01

110

Quantum description of nuclear spin cooling in a quantum dot

NASA Astrophysics Data System (ADS)

We study theoretically the cooling of an ensemble of nuclear spins coupled to the spin of a localized electron in a quantum dot. We obtain a master equation for the state of the nuclear spins interacting with a sequence of polarized electrons that allows us to study quantitatively the cooling process including the effect of nuclear spin coherences, which can lead to “dark states” of the nuclear system in which further cooling is inhibited. We show that the inhomogeneous Knight field mitigates this effect strongly and that the remaining dark-state limitations can be overcome by very few shifts of the electron wave function, allowing for cooling far beyond the dark-state limit. Numerical integration of the master equation indicates that polarizations larger than 90% can be achieved within a millisecond time scale.

Christ, H.; Cirac, J. I.; Giedke, G.

2007-04-01

111

Matrix Formalism for Spin Dynamics Near a Single Depolarization Resonance

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

Chao, Alexander W.; /SLAC

2005-10-26

112

Azimuthal and Single Spin Asymmetries in Hard Scattering Processes

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

U. D'Alesio; F. Murgia

2007-12-28

113

Nuclear Spins in a Nanoscale Device for Quantum Information Processing

Coherent oscillations between any two levels from four nuclear spin states of I=3/2 have been demonstrated in a nanometre-scale NMR semiconductor device, where nuclear spins are all-electrically controlled. Using this device, we discuss quantum logic operations on two fictitious qubits of the I=3/2 system, and propose a quantum state tomography scheme based on the measurement of longitudinal magnetization, $M_z$.

S. K. Ozdemir; A. Miranowicz; T. Ota; G. Yusa; N. Imoto; Y. Hirayama

2006-12-29

114

Interaction induced deformation in momentum distribution of spin polarized nuclear matter

Effects of spin polarization on the structure of symmetric nuclear matter and pure neutron matter are investigated. We show that the spin polarization induces a deformation of the Fermi spheres for nucleons with spin parallel and opposite to the polarization axes. This feature can be related to the structure of the one pion exchange contribution to a realistic nucleon-nucleon interaction. While the anisotropies in the momentum distribution lower the energy of the system by small amount, the associated variations of the single particle energies with the angle between the polarization axis and the particle momentum are significant.

T. Frick; H. Müther; A. Sedrakian

2002-03-19

115

Dominant Contribution in Pion Production Single-Spin Asymmetries

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

Ratcliffe, Philip G

2008-01-01

116

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

Budker, Dmitry

117

Using nanoscale transistors to measure single donor spins in semiconductors

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

118

NASA Astrophysics Data System (ADS)

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

Mayhall, Nicholas J.; Head-Gordon, Martin

2014-10-01

119

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

Mayhall, Nicholas J; Head-Gordon, Martin

2014-10-01

120

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

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

2014-10-09

121

Control of single-spin magnetic anisotropy by exchange coupling

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

122

Calculation of nuclear spin-spin coupling constants using frozen density embedding

NASA Astrophysics Data System (ADS)

We present a method for a subsystem-based calculation of indirect nuclear spin-spin coupling tensors within the framework of current-spin-density-functional theory. Our approach is based on the frozen-density embedding scheme within density-functional theory and extends a previously reported subsystem-based approach for the calculation of nuclear magnetic resonance shielding tensors to magnetic fields which couple not only to orbital but also spin degrees of freedom. This leads to a formulation in which the electron density, the induced paramagnetic current, and the induced spin-magnetization density are calculated separately for the individual subsystems. This is particularly useful for the inclusion of environmental effects in the calculation of nuclear spin-spin coupling constants. Neglecting the induced paramagnetic current and spin-magnetization density in the environment due to the magnetic moments of the coupled nuclei leads to a very efficient method in which the computationally expensive response calculation has to be performed only for the subsystem of interest. We show that this approach leads to very good results for the calculation of solvent-induced shifts of nuclear spin-spin coupling constants in hydrogen-bonded systems. Also for systems with stronger interactions, frozen-density embedding performs remarkably well, given the approximate nature of currently available functionals for the non-additive kinetic energy. As an example we show results for methylmercury halides which exhibit an exceptionally large shift of the one-bond coupling constants between 199Hg and 13C upon coordination of dimethylsulfoxide solvent molecules.

Götz, Andreas W.; Autschbach, Jochen; Visscher, Lucas

2014-03-01

123

Strong driving of a single spin using arbitrarily polarized fields

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

124

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

125

Nuclear spin-induced Cotton-Mouton effect in molecules.

In nuclear magneto-optic spectroscopy, effects of nuclear magnetization are detected in light passing through a sample containing spin-polarized nuclei. An optical analogue of nuclear magnetic resonance (NMR) chemical shift has been predicted and observed in the nuclear spin optical rotation of linearly polarized light propagating parallel to the nuclear magnetization. A recently proposed magneto-optic analogue of the NMR spin-spin coupling, the nuclear spin-induced Cotton-Mouton (NSCM) effect entails an ellipticity induced to linearly polarized light when passing through a medium with the nuclear spins polarized in a direction perpendicular to the light beam. Here we present a first-principles electronic structure formulation of NSCM in terms of response theory as well as ab initio and density-functional theory calculations for small molecules. The roles of basis set (we use completeness-optimized sets), electron correlation, and relativistic effects are discussed. It is found that the explicitly temperature-dependent contribution to NSCM, arising from the partial orientation of the molecules due to the nuclear magnetization, typically dominates the effect. This part of NSCM is proportional to the tensor product of molecular polarizability and the NMR direct dipolar coupling tensor. Hence, NSCM provides a means of investigating the dipolar coupling and, thus, molecular structure in a formally isotropic medium. Overall ellipticities of the order of magnitude of 10(-8)...10(-7) rad/(M cm) are predicted for fully polarized nuclei. These should be detectable with modern instrumentation in the Voigt setup. PMID:23742457

Fu, Li-juan; Vaara, Juha

2013-05-28

126

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

127

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

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

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

2014-04-18

128

Single-Spin Asymmetries in Pion Electroproduction at CLAS

NASA Astrophysics Data System (ADS)

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

Avagyan, Harut

2002-04-01

129

Electron and nuclear spins in semiconductor quantum dots

NASA Astrophysics Data System (ADS)

The electron and nuclear spin degrees of freedom in two-dimensional semiconductor quantum dots are studied as important resources for such fields as spintronics and quantum information. The coupling of electron spins to their orbital motion, via the spin-orbit interaction, and to nuclear spins, via the hyperfine interaction, are important for understanding spin-dynamics in quantum dot systems. This work is concerned with both of these interactions as they relate to two-dimensional semiconductor quantum dots. We first consider the spin-orbit interaction in many-electron quantum dots, studying its role in conductance fluctuations. We further explore the creation and destruction of spin-polarized currents by chaotic quantum dots in the strong spin-orbit limit, finding that even without magnetic fields or ferromagnets (i.e., with time reversal symmetry) such systems can produce large spin-polarizations in currents passing through a small number of open channels. We use a density matrix formalism for transport through quantum dots, allowing consideration of currents entangled between different leads, which we show can have larger fluctuations than currents which are not so entangled. Second, we consider the hyperfine interaction between electrons and approximately 106 nuclei in two-electron double quantum dots. The nuclei in each dot collectively form an effective magnetic field interacting with the electron spins. We show that a procedure originally explored with the intent to polarize the nuclei can also equalize the effective magnetic fields of the nuclei in the two quantum dots or, in other parameter regimes, can cause the effective magnetic fields to have large differences.

Krich, Jacob Jonathan

130

Imaging mesoscopic nuclear spin noise with a diamond magnetometer

Magnetic Resonance Imaging (MRI) can characterize and discriminate among tissues using their diverse physical and biochemical properties. Unfortunately, submicrometer screening of biological specimens is presently not possible, mainly due to lack of detection sensitivity. Here we analyze the use of a nitrogen-vacancy center in diamond as a magnetic sensor for nanoscale nuclear spin imaging and spectroscopy. We examine the ability of such a sensor to probe the fluctuations of the "classical" dipolar field due to a large number of neighboring nuclear spins in a densely protonated sample. We identify detection protocols that appropriately take into account the quantum character of the sensor and find a signal-to-noise ratio compatible with realistic experimental parameters. Through various example calculations we illustrate different kinds of image contrast. In particular, we show how to exploit the comparatively long nuclear spin correlation times to reconstruct a local, high-resolution sample spectrum.

C. A. Meriles; L. Jiang; G. Goldstein; J. S. Hodges; J. R. Maze; M. D. Lukin; P. Cappellaro

2010-04-30

131

Tilted Foils Nuclear Spin Polarization at REX-ISOLDE

This thesis will explain and summarize my work and involvement in experiments aimed at producing nuclear spin polarization of post-accelerated beams of ions with the tilted-foils technique at the REX-ISOLDE linear accelerator at CERN. Polarizing the nuclear spin of radioactive beams in particular may provide access to observables which may be difficult to obtain otherwise. Currently, the techniques commonly employed for nuclear spin polarization are restricted to specific nuclides and experimental measurement techniques. Tilted foils polarization may provide a new tool to extend the range of nuclides that can be polarized and the types of experiments that can be performed. The experiments rely not only on the production but also on the method to measure the degree of attained polarization. Two methods will be treated, based on particle scattering in Coulomb excitation that may be utilized for stable beams, and the $\\beta$-NMR that requires $\\beta$-decaying nuclei. The experimental setups and measurements will...

Törnqvist, Hans Toshihide

2013-08-08

132

Quantum Information Transport in Nuclear Spin Chains

In many solid-state proposals for quantum computers, the transport of information over relatively short distances inside the quantum processor itself is an essential task, and one for which relying on photons, and therefore on a frequent exchanging of information between solid-state and light qubits, could be too costly. Quantum wires based on spins could be a viable alternative leading to

Paola Cappellaro; David Cory

2007-01-01

133

Direct observation of a nuclear spin excitation in Ho2Ti2O7.

A single nondispersive excitation is observed by means of neutron backscattering, at E_{0}=26.3 microeV in the spin ice Ho2Ti2O7 but not in the isotopically enriched 162Dy2Ti2O7 analogue. The intensity of this excitation is rather small, less, similar0.2% of the elastic intensity. It is clearly observed below 80 K but resolution limited only below approximately 65 K. The application of a magnetic field up to micro_{0}H=4.5 T, at 1.6 K, has no measurable effect on the energy or intensity. This nuclear excitation is believed to perturb the electronic, Ising spin system resulting in the persistent spin dynamics observed in spin ice compounds. PMID:19257221

Ehlers, G; Mamontov, E; Zamponi, M; Kam, K C; Gardner, J S

2009-01-01

134

Direct Observation of a Nuclear Spin Excitation in Ho2Ti2O7

NASA Astrophysics Data System (ADS)

A single nondispersive excitation is observed by means of neutron backscattering, at E0=26.3?eV in the spin ice Ho2Ti2O7 but not in the isotopically enriched Dy2162Ti2O7 analogue. The intensity of this excitation is rather small, ?0.2% of the elastic intensity. It is clearly observed below 80 K but resolution limited only below ˜65K. The application of a magnetic field up to ?0H=4.5T, at 1.6 K, has no measurable effect on the energy or intensity. This nuclear excitation is believed to perturb the electronic, Ising spin system resulting in the persistent spin dynamics observed in spin ice compounds.

Ehlers, G.; Mamontov, E.; Zamponi, M.; Kam, K. C.; Gardner, J. S.

2009-01-01

135

COMPASS Results on Transverse Single-Spin Asymmetries

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

Anna Martin

2007-02-01

136

Dynamic nuclear polarization from current-induced electron spin polarization

NASA Astrophysics Data System (ADS)

Current-induced electron spin polarization is shown to produce nuclear hyperpolarization through dynamic nuclear polarization. Saturated fields of several millitesla are generated upon the application of an electric field over a time scale of 100 s in InGaAs epilayers and measured using optical Larmor magnetometry. We show that, in contrast to previous demonstrations of current-induced dynamic nuclear polarization, the direction of the current relative to the crystal axis and external magnetic field may be used to control the magnitude and direction of the saturation nuclear field.

Trowbridge, C. J.; Norman, B. M.; Kato, Y. K.; Awschalom, D. D.; Sih, V.

2014-08-01

137

Method for nuclear spin statistics in molecular spectroscopy

Using spin projection operator methods, generating functions are developed for nuclear spin species. These operators also generate elegantly the irreducible respresentations spanned by a/sub 1//sup b//sub 1/ a/sub 2//sup b//sub 2/xxxa/sub t//sup b//sub t/ nuclear spin functions, where a/sub i/ is the number of possible spin states of the b/sub i/ nuclei of the same kind in the molecule. From these generating functions the statistical weights of the rovibronic levels of any polyatomic molecule can be obtained easily. The method is illustrated with /sup 33/SF/sub 6/, /sup 13/C-triphenylene, and triphenylene with protons replaced by D. For /sup 13/C-triphenylene there are 1 073 741 824 nuclear spin functions from which we determined the statistical weights of the rovibronic levels A/sup prime//sub 1/, A/sup prime//sub 2/, E', A/sup double-prime//sub 1/, A/sup double-prime//sub 2/, and E'' to be 178 940 928, 178 973 696, 357 913 600, 178 940 928, 178 973 696, and 357 913 600, respectively.

Balasubramanian, K.

1981-06-15

138

A METHOD FOR NUCLEAR SPIN STATISTICS IN MOLECULAR SPECTROSCOPY

Using spin projection operator methods generating functions are developed for nuclear spin species. These operators also generate elegantly the irreducible representations spanned by a{sub 1}{sup b{sub 1}}, a{sub 2}{sup b{sub 2}} .... a{sub t}{sup b{sub t}} nuclear spin functions where a{sub i} is the number of possible spin states of the b{sub i} nuclei of the same kind in the molecule. From these generating functions the statistical weights of the rovibronic levels of any polyatomic molecule can be obtained easily. The method is illustrated with SF{sub 6}, C{sup 13}-Triphenylene and triphenylene with protons replaced by D. For C{sup 13}-Triphenylene there are 1073741824 nuclear spin functions from which we determine the statistical weights of the rovibronic levels A{sub 1}, A{sub 2}, E, A{sub 1}', A{sub 2}' and E' to be 178940928, 178973696, 357913600, 178940928, 178973696, and 357913600, respectively.

Balasubramanian, K.

1980-10-01

139

Dependence of nuclear spin singlet lifetimes on RF spin-locking power

We measure the lifetime of long-lived nuclear spin singlet states as a function of the strength of the RF spin-locking field and present a simple theoretical model that agrees well with our measurements, including the low-RF-power regime. We also measure the lifetime of a long-lived coherence between singlet and triplet states that does not require a spin-locking field for preservation. Our results indicate that for many molecules, singlet states can be created using weak RF spin-locking fields: more than two orders of magnitude lower RF power than in previous studies. Our findings suggest that in many biomolecules, singlets and related states with enhanced lifetimes might be achievable in vivo with safe levels of RF power.

Stephen J. DeVience; Ronald L. Walsworth; Matthew S. Rosen

2012-01-06

140

Hole - Nuclear Spin Interaction in Semiconductor Quantum Dots

NASA Astrophysics Data System (ADS)

Spins of localized electrons in semiconductor quantum dots (QDs) are attractive for future spintronic and quantum information devices since they are not subject to the classical spin relaxation mechanisms known for free carriers [1]. It is now well established that the main spin dephasing mechanism in QDs is due to the coupling of conduction electron spin with the randomly fluctuating nuclear spins (Fermi contact term) [2-5]. For a valence electron (or hole), this coupling is expected to be much weaker because of the p-symmetry of the valence band states and no experimental evidence of such a hole-nuclear spin interaction has been reported so far [6]. We have measured the carrier spin dynamics in p-doped InAs/GaAs quantum dots by pump probe and time-resolved photoluminescence experiments. We demonstrate that the hole spin dynamics in these QDs is governed by the interaction with randomly fluctuating nuclear spins [7]. Our calculations based on dipole-dipole coupling between the hole and the quantum dot nuclei lead to a hole spin dephasing time for an ensemble of dots of 15 ns in close agreement with experiments.[4pt] In collaboration with B. Eble, C. Testelin, F. Bernardot, and M. Chamarro, Institut des Nanosciences de Paris, Universit'e P. et M. Curie, CNRS, Paris, F-75015 France; A. Balocchi, T. Amand, and B. Urbaszek, Universit'e de Toulouse ; LPCNO, INSA-CNRS-UPS, 135 av. de Rangueil, 31077 Toulouse Cedex 4, France; and A. Lemaître, Laboratoire de Photonique et de Nanostructures, CNRS, Route de Nozay, F-91460, Marcoussis, France. [4pt] [1] Spin Physics in Semiconductors, edited by M. D'Yakonov (Springer, Berlin, 2008) [0pt] [2] I. Merkulov et al, Phys. Rev. B 65, 205309 (2002) [0pt] [3] P.-F. Braun, X. Marie et al, PRL 94, 116601 (2005) [0pt] [4] A. C. Johnson et al , Nature 435, 925 (2005) [0pt] [5] A. Greilich et al, Science 313, 341(2006) [0pt] [6] S. Laurent et al, Phys. Rev. Lett. 94, 147401 (2005) [0pt] [7] B. Eble et al, Phys. Rev. Lett. 102, 146601 (2009)

Marie, Xavier

2010-03-01

141

Nuclear Spin Gyroscope Based on an Atomic Comagnetometer

We describe a nuclear spin gyroscope based on an alkali-metal-noble-gas comagnetometer. Optically pumped alkali-metal vapor is used to polarize the noble-gas atoms and detect their gyroscopic precession. Spin precession due to magnetic fields as well as their gradients and transients can be cancelled in this arrangement. The sensitivity is enhanced by using a high-density alkali-metal vapor in a spin-exchange relaxation free regime. With a K-{sup 3}He comagnetometer we demonstrate rotation sensitivity of 5x10{sup -7} rad s{sup -1} Hz{sup -1/2}, equivalent to a magnetic field sensitivity of 2.5 fT/Hz{sup 1/2}. The rotation signal can be increased by a factor of 10 using {sup 21}Ne with a smaller magnetic moment. The comagnetometer is also a promising tool in searches for anomalous spin couplings beyond the standard model.

Kornack, T.W.; Ghosh, R.K.; Romalis, M.V. [Department of Physics, Princeton University, Princeton, New Jersey 08550 (United States)

2005-12-02

142

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

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

Yang, Jamie Chiaming

2008-01-01

143

Chemical Distinction by Nuclear Spin Optical Rotation Suvi Ikalainen

surroundings of magnetic nuclei. Efficient first-principles calculations for isolated water, ethanol, in which the magnetic field due to spin- polarized nuclei causes the plane of polarization of an incident microscopic property, the dependence of optical polarizability on the nuclear magnetic moment, the laser

Romalis, Mike

144

Spins as qubits: Quantum information processing by nuclear magnetic resonance

of the amount of energy dissipated per logical operation in successive generations of computer hardware. SomeSpins as qubits: Quantum information processing by nuclear magnetic resonance Dieter Suter1,a and T 2007; published online 5 February 2008 Storing information in quantum mechanical degrees of freedom

Suter, Dieter

145

Nuclear spin dynamics in parabolic quantum wells Ionel Tifrea* and Michael E. Flatte

Nuclear spin dynamics in parabolic quantum wells Ionel TÂ¸ifrea* and Michael E. FlatteÂ´ Department March 2004 We present a detailed analytical and numerical analysis of the nuclear spin dynamics of the electronic wave function in small electric fields. The nuclear spin relaxation via the hyperfine interaction

Flatte, Michael E.

146

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

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

Boutis, Gregory Steven, 1975-

2002-01-01

147

The qubit states decoherence in antiferromagnet-based nuclear spin model of quantum register

This study deals with the further development of nuclear spin model of scalable quantum register, which presents the one-dimensional chain of the magnetic atoms with nuclear spins 1/2, substituting the basic atoms in the plate of nuclear spin-free easy-axis 3D antiferromagnet. The decoherence rates of one qubit state and entanglement state of two removed qubits and longitudinal relaxation rates are caused by the interaction of nuclear spins-qubits with virtual spin waves in antiferromagnet ground state were calculated. It was considered also one qubit adiabatic decoherence, is caused by the interaction of nuclear spin of quantum register with nuclear spins of randomly distributed isotopes, substituting the basic nuclear spin-free isotopes of antiferromagnet. We have considered finally encoded DFS (Decoherence-Free Subspaces) logical qubits are constructed on clusters of the four-physical qubits, given by the two states with zero total angular momentum.

A. A. Kokin; V. A. Kokin

2010-03-01

148

Observation of scalar nuclear spin–spin coupling in van der Waals complexes

Scalar couplings between covalently bound nuclear spins are a ubiquitous feature in nuclear magnetic resonance (NMR) experiments, imparting valuable information to NMR spectra regarding molecular structure and conformation. Such couplings arise due to a second-order hyperfine interaction, and, in principle, the same mechanism should lead to scalar couplings between nuclear spins in unbound van der Waals complexes. Here, we report the first observation of scalar couplings between nuclei in van der Waals complexes. Our measurements are performed in a solution of hyperpolarized 129Xe and pentane, using superconducting quantum interference devices to detect NMR in 10 mG fields, and are in good agreement with calculations based on density functional theory. van der Waals forces play an important role in many physical phenomena. The techniques presented here may provide a new method for probing such interactions.

Ledbetter, Micah P.; Saielli, Giacomo; Bagno, Alessandro; Tran, Nhan; Romalis, Michael V.

2012-01-01

149

Search for an Atomic EDM with Optical-Coupling Nuclear Spin Oscillator

NASA Astrophysics Data System (ADS)

We have constructed a nuclear spin oscillator of a new type, that employs a feedback scheme based on an optical spin detection and suceeding spin control by a transverse field application. This spin oscillator parallels the conventional spin maser in many points, but exhibits advantages and requirements that are different from those with the spin maser. By means of the optical-coupling nuclear spin oscillator, an experimental setup to search for an electric dipole moment (EDM) in a spin 1/2 diamagnetic atom 129Xe is being developed.

Asahi, K.; Uchida, M.; Yoshimi, A.; Inoue, T.; Hatakeyama, N.

2007-06-01

150

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

151

Room-temperature optical manipulation of nuclear spin polarization in GaAsN

NASA Astrophysics Data System (ADS)

The effect of hyperfine interaction on the room-temperature defect-enabled spin filtering effect in GaAsN alloys is experimentally investigated and theoretically interpreted through a master equation approach based on the hyperfine and Zeeman interaction between electron and nuclear spin of the Gai2+ interstitial spin filtering defect. We show that the nuclear spin polarization of the gallium defect can be tuned through the optically induced spin polarization of conduction band electrons.

Sandoval-Santana, C.; Balocchi, A.; Amand, T.; Harmand, J. C.; Kunold, A.; Marie, X.

2014-09-01

152

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

153

Dynamics of Overhauser Field under nuclear spin diffusion in a quantum dot

The coherence of electron spin can be significantly enhanced by locking the Overhauser field from nuclear spins using the nuclear spin preparation. We propose a theoretical model to calculate the long time dynamics of the Overhauser field under intrinsic nuclear spin diffusion in a quantum dot. We obtain a simplified diffusion equation that can be numerically solved and show quantitatively how the Knight shift and the electron-mediated nuclear spin flip-flop affect the nuclear spin diffusion. The results explain several recent experimental observations, where the decay time of Overhauser field is measured under different configurations, including variation of the external magnetic field, the electron spin configuration in a double dot, and the initial nuclear spin polarization rate.

Zhe-Xuan Gong; Zhang-qi Yin; L. -M. Duan

2009-12-22

154

Nuclear spin relaxation due to random motion of vortex bundles

The dependence of nuclear-spin-relaxation rate {ital T}{sub 1} on NMR resonant frequency for a layered superconducting sample has been analyzed theoretically. In the considered arrangement the Zeeman field has been applied in the plane of superconducting layers while the relaxation was due to interactions between the spin systems and moving flux bundles, created by the transport current flowing along superconducting layers. It has been found that the functional form of a dependence of spin-relaxation rate on the Zeeman field has two components, a Lorentzian and an oscillatory one. The characteristic rolloff frequency of the Lorentzian component depends on the pinning properties of the sample. The period of oscillations of the oscillatory component is of the order of the inverse of interaction time of flowing flux bundles with a probe nucleus. {copyright} {ital 1996 The American Physical Society.}

Ashkenazy, V.D. [Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel)] [Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel); Jung, G. [Department of Physics, Ben Gurion University of the Negev, 84105 Beer-Sheva (Israel)] [Department of Physics, Ben Gurion University of the Negev, 84105 Beer-Sheva (Israel); [Institute Fizyki PAN, 02668 Warszawa (Poland); Shapiro, B.Y. [Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel)] [Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel); [Jack and Pearl Resnick Institute of Advanced Technology and the Center of Superconductivity, Bar-Ilan University, 52100, Ramat Gan (Israel)

1996-02-01

155

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

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

2014-11-01

156

Nuclear Magnetic Resonance (NMR) This technique observes signals from nuclear spins

magnetic moment () The Bohr model of H atom electron Nucleus I I = n I An intrinsic property of the nucleus alter the alignment of this magnetization, causing the hydrogen nuclei to produce a rotating magnetic #12; Nuclear Magnetic Resonance (NMR) This technique observes signals from nuclear spins

Chen, Yang-Yuan

157

Effective ergodicity in single-spin-flip dynamics

NASA Astrophysics Data System (ADS)

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

Süzen, Mehmet

2014-09-01

158

Hadronic single spin asymmetries at large P sub T

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

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

1991-04-20

159

Nuclear spin circular dichroism in fullerenes: a computational study.

In the recently proposed phenomenon, nuclear spin-induced circular dichroism (NSCD), collective magnetisation of nuclei induces circular dichroism in a light beam passing through a molecular sample. Here we present the first computational predictions of NSCD for fullerenes C60 and C70. We show that the NSCD signal is nucleus-specific, like in NMR spectroscopy. Thus, NSCD may provide a new and promising, high-resolution observable for experimental identification of chemical compounds. PMID:25341745

Straka, Michal; St?pánek, Petr; Coriani, Sonia; Vaara, Juha

2014-11-01

160

Nuclear Spin Relaxation and the Collision Frequency in Dense Gases

The relation between nuclear spin-lattice relaxation (T1) measurements and the collision frequency in dense gases is discussed. It is shown that the density dependence of T1 in compressed H2 gas can be accounted for by assuming a hard-sphere potential model and evaluating the Enskog correction to the collision frequency in a dense fluid. This comparison represents the first direct test

R. G. Gordon; R. L. Armstrong; E. Tward

1968-01-01

161

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

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

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

2013-04-19

162

Interlayer diffusion of nuclear spin polarization in ? =2/3 quantum Hall states

NASA Astrophysics Data System (ADS)

At the spin transition point of ? =2/3 quantum Hall states, nuclear spins in a two-dimensional electron gas are polarized by an electric current. Using GaAs/AlGaAs double-quantum-well samples, we first observed the spatial diffusion of nuclear spin polarization between the two layers when the nuclear spin polarization is current induced in one layer. By numerical simulation, we estimated the diffusion constant of the nuclear spin polarization to be 15±7nm2/s.

Nguyen, Minh-Hai; Tsuda, Shibun; Terasawa, Daiju; Fukuda, Akira; Zheng, Yangdong; Sawada, Anju

2014-01-01

163

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

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

2008-01-01

164

Manipulation of the nuclear spin ensemble in a quantum dot with chirped magnetic resonance pulses

NASA Astrophysics Data System (ADS)

The nuclear spins in nanostructured semiconductors play a central role in quantum applications. The nuclear spins represent a useful resource for generating local magnetic fields but nuclear spin noise represents a major source of dephasing for spin qubits. Controlling the nuclear spins enhances the resource while suppressing the noise. NMR techniques are challenging: the group III and V isotopes have large spins with widely different gyromagnetic ratios; in strained material there are large atom-dependent quadrupole shifts; and nanoscale NMR is hard to detect. We report NMR on 100,000 nuclear spins of a quantum dot using chirped radiofrequency pulses. Following polarization, we demonstrate a reversal of the nuclear spin. We can flip the nuclear spin back and forth a hundred times. We demonstrate that chirped NMR is a powerful way of determining the chemical composition, the initial nuclear spin temperatures and quadrupole frequency distributions for all the main isotopes. The key observation is a plateau in the NMR signal as a function of sweep rate: we achieve inversion at the first quantum transition for all isotopes simultaneously. These experiments represent a generic technique for manipulating nanoscale inhomogeneous nuclear spin ensembles and open the way to probe the coherence of such mesoscopic systems.

Munsch, Mathieu; Wüst, Gunter; Kuhlmann, Andreas V.; Xue, Fei; Ludwig, Arne; Reuter, Dirk; Wieck, Andreas D.; Poggio, Martino; Warburton, Richard J.

2014-09-01

165

Spin-locking of half-integer quadrupolar nuclei, such as 23Na (I=3/2) and 27Al (I=5/2), is of renewed interest owing to the development of variants of the multiple-quantum and satellite-transition magic angle spinning (MAS) nuclear magnetic resonance experiments that either utilize spin-locking directly or offer the possibility that spin-locked states may arise. However, the large magnitude and, under MAS, the time dependence of the quadrupolar interaction often result in complex spin-locking phenomena that are not widely understood. Here we show that, following the application of a spin-locking pulse, a variety of coherence transfer processes occur on a time scale of approximately 1/omegaQ before the spin system settles down into a spin-locked state which may itself be time dependent if MAS is performed. We show theoretically for both spin I=3/2 and 5/2 nuclei that the spin-locked state created by this initial rapid dephasing typically consists of a variety of single- and multiple-quantum coherences and nonequilibrium population states and we discuss the subsequent evolution of these under MAS. In contrast to previous work, we consider spin-locking using a wide range of radio frequency field strengths, i.e., a range that covers both the "strong-field" (omega1 > omegaQPAS and "weak-field" (omega1 < omegaQPAS limits. Single- and multiple-quantum filtered spin-locking experiments on NaNO2, NaNO3, and Al(acac)3, under both static and MAS conditions, are used to illustrate and confirm the results of the theoretical discussion. PMID:15268416

Ashbrook, Sharon E; Wimperis, Stephen

2004-02-01

166

Solid effect in magic angle spinning dynamic nuclear polarization

For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}\\omega _0 ^{ - 2}\\end{equation*} \\end{document}?0?2 field dependence. In particular, for nominally forbidden zero and double quantum SE transitions to be partially allowed, it is necessary for mixing of adjacent nuclear spin states to occur, and this leads to the observed field dependence. However, recently we have improved our instrumentation and report here an enhancement of ? = 91 obtained with the organic radical trityl (OX063) in magic angle spinning experiments performed at 5 T and 80 K. This is a factor of 6-7 higher than previous values in the literature under similar conditions. Because the solid effect depends strongly on the microwave field strength, we attribute this large enhancement to larger microwave field strengths inside the sample volume, achieved with more efficient coupling of the gyrotron to the sample chamber. In addition, we develop a theoretical model to explain the dependence of the buildup rate of enhanced nuclear polarization and the steady-state enhancement on the microwave power. Buildup times and enhancements were measured as a function of 1H concentration for both trityl and Gd-DOTA. Comparison of the results indicates that for trityl the initial polarization step is the slower, rate-determining step. However, for Gd-DOTA the spread of nuclear polarization via homonuclear 1H spin diffusion is rate-limiting. Finally, we discuss the applicability of the solid effect at fields > 5 T and the requirements to address the unfavorable field dependence of the solid effect. PMID:22894339

Corzilius, Bjorn; Smith, Albert A.; Griffin, Robert G.

2012-01-01

167

Nuclear Spin Maser at Highly Stabilized Low Magnetic Field and Search for Atomic EDM

NASA Astrophysics Data System (ADS)

A nuclear spin maser is operated at a low static field through an active feedback scheme based on an optical nuclear spin detection and succeeding spin control by a transverse field application. The frequency stability of this optical-coupling spin maser is improved by installation of a low-noise current source for a solenoid magnet producing a static magnetic field in the maser operation. Experimental devices for application of the maser to EDM experiment are being developed.

Yoshimi, A.; Asahi, K.; Inoue, T.; Uchida, M.; Hatakeyama, N.; Tsuchiya, M.; Kagami, S.

2009-08-01

168

Voltage tunability of single spin-states in a quantum dot

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

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

2013-02-27

169

Stable Three-Axis Nuclear Spin Gyroscope in Diamond

We propose a sensitive and stable three-axis gyroscope in diamond. We achieve high sensitivity by exploiting the long coherence time of the N14 nuclear spin associated with the Nitrogen-Vacancy center in diamond, and the efficient polarization and measurement of its electronic spin. While the gyroscope is based on a simple Ramsey interferometry scheme, we use coherent control of the quantum sensor to improve its coherence time as well as its robustness against long-time drifts, thus achieving a very robust device with a resolution of 0.5mdeg/s/(Hz mm^3)^(1/2). In addition, we exploit the four axes of delocalization of the Nitrogen-Vacancy center to measure not only the rate of rotation, but also its direction, thus obtaining a compact three-axis gyroscope.

Ajoy, Ashok

2012-01-01

170

Stable Three-Axis Nuclear Spin Gyroscope in Diamond

We propose a sensitive and stable three-axis gyroscope in diamond. We achieve high sensitivity by exploiting the long coherence time of the N14 nuclear spin associated with the Nitrogen-Vacancy center in diamond, and the efficient polarization and measurement of its electronic spin. While the gyroscope is based on a simple Ramsey interferometry scheme, we use coherent control of the quantum sensor to improve its coherence time as well as its robustness against long-time drifts, thus achieving a very robust device with a resolution of 0.5mdeg/s/(Hz mm^3)^(1/2). In addition, we exploit the four axes of delocalization of the Nitrogen-Vacancy center to measure not only the rate of rotation, but also its direction, thus obtaining a compact three-axis gyroscope.

Ashok Ajoy; Paola Cappellaro

2012-05-07

171

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

172

Spin-path entanglement in single-neutron interferometer experiments

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

173

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

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

174

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

175

NASA Astrophysics Data System (ADS)

This work presents the results of various investigations using various techniques of hyperpolarizing the nuclei of atoms. Hyperpolarization implies magnetic order in excess of the thermal order obtained naturally as described by Curie's law. The main portion of this work presents the results of a detailed experimental exploration of predictions arising from a new model of transverse nuclear spin relaxation in quantum systems, based on possible manifestations of microscopic chaos in quantum systems. Experiments have been carried out on a number of hyperpolarized xenon samples, each differing in its relative percentage of xenon isotopes in order to vary the homonuclear and heteronuclear dipole couplings in the spin system. The experiments were performed under a variety of conditions in an attempt to observe the behaviors predicted by the model. Additionally, much more extensive measurements were made on a number of samples of solid CaF2 in both single crystal and powder forms. These samples, although thermally polarized, were observed with superior signal to noise ratios than even the hyperpolarized xenon solids, allowing for more precise measurements for comparison to the theory. This work thus contains the first experimental evidence for the majority of the model's predictions. Additionally, this work contains the first precise measurements of the frequency-shift enhancement parameters for 129Xe and krypton in the presence of spin-polarized Rb. The determination of these important numbers will be useful to many groups who utilize spin-exchange optical pumping in their labs. This work built on the prior knowledge of a precise number for the frequency-shift enhancement parameter of 3He in Rb vapor. Finally, I detail work using NMR to detect nuclear-spin polarization enhancement in silicon phosphorus by a novel, photo-induced hyperpolarization technique developed by the Boehme research group at the University of Utah. Significant nuclear polarization enhancements were observed by the Boehme group due to electron-photon interactions in semiconductor soilds; these enhancements were observed by their effects on the ambient electrons and measured with electron spin resonance techniques. The work described here details experiments to observe the enhanced nuclear polarization by directly measuring the intensity increase in an NMR measurement. I will conclude this dissertation with a brief appendix giving a summary of one additional project involving the use of high pressure fluorinated gas NMR to measure the internal topology and characteristics of energy-rich oil shales.

Sorte, Eric G.

176

Estimation of optical chemical shift in nuclear spin optical rotation

NASA Astrophysics Data System (ADS)

A recently proposed optical chemical shift in nuclear spin optical rotation (NSOR) is studied by theoretical comparison of NSOR magnitude between chemically non-equivalent or different element nuclei in the same molecule. Theoretical expressions of the ratio R between their NSOR magnitudes are derived by using a known semi-empirical formula of NSOR. Taking methanol, tri-ethyl-phosphite and 2-methyl-benzothiazole as examples, the ratios R are calculated and the results approximately agree with the experiments. Based on those, the important influence factors on R and chemical distinction by NSOR are discussed.

Chen, Fang; Yao, Guo-hua; He, Tian-jing; Chen, Dong-ming; Liu, Fan-chen

2014-05-01

177

Spin Instability in Nuclear Matter and the Skyrme Interaction

NASA Astrophysics Data System (ADS)

In the present work the problem of spin instability of nuclear matter with the Skyrme interaction is analyzed. The three-body part of the interaction is replaced by using a density dependent potential which is a modification to that given previously by Dabrowski. The symmetry energies are calculated and their rearrangement corrections. Good agreement is obtained with previous calculations.Translated AbstractSpininstabilität in Kernmaterie und Skyrme-WechselwirkungDie vorliegende Arbeit analysiert die Spininstabilität von Kernmaterie mit Skyrme-Wechselwirkung. Der Dreikörperanteil der Wechselwirkung ist durch ein dichteabhängiges Potential ersetzt. Die Symmetrieenergien und ihre Umordnungskorrekturen werden berechnet. Sie stimmen gut mit vorhergehenden Rechnungen überein.

Mansour, H. M. M.

178

The water-endofullerene H2O@C60 provides a unique chemical system in which freely rotating water molecules are confined inside homogeneous and symmetrical carbon cages. The spin conversion between the ortho and para species of the endohedral H2O was studied in the solid phase by low-temperature nuclear magnetic resonance. The experimental data are consistent with a second-order kinetics, indicating a bimolecular spin conversion process. Numerical simulations suggest the simultaneous presence of a spin diffusion process allowing neighbouring ortho and para molecules to exchange their angular momenta. Cross-polarization experiments found no evidence that the spin conversion of the endohedral H2O molecules is catalysed by (13)C nuclei present in the cages. PMID:24852537

Mamone, Salvatore; Concistrè, Maria; Carignani, Elisa; Meier, Benno; Krachmalnicoff, Andrea; Johannessen, Ole G; Lei, Xuegong; Li, Yongjun; Denning, Mark; Carravetta, Marina; Goh, Kelvin; Horsewill, Anthony J; Whitby, Richard J; Levitt, Malcolm H

2014-05-21

179

As a nuclear spin model of scalable quantum register, the one-dimensional chain of the magnetic atoms with nuclear spins 1/2 substituting the basic atoms in the plate of nuclear spin free easy-axis 3D antiferromagnet is considered. It is formulated the generalized antiferromagnet Hamiltonian in spin-wave approximation (low temperatures) considering the inhomogeneous external magnetic field, which is directed along the easy axis normally to plane of the plate and has a constant gradient along the nuclear spin chain. Assuming a weak gradient, the asymptotic expression for coefficients of unitary transformations to the diagonal form of antiferromagnet Hamiltonian is found. With this result the expression for indirect interspin coupling, which is due to hyperfine nuclear electron coupling in atoms and the virtual spin wave propagation in antiferromagnet ground state, was evaluated. It is shown that the inhomogeneous magnetic field essentially modifies the characteristics of indirect interspin coupling. The indirect interaction essentially grows and even oscillates in relation to the interspin distance when the local field value in the middle point of two considered nuclear spin is close to the critical field for quantum phase transition of spin-flop type in bulk antiferromagnet or close to antiferromagnetic resonance. Thus, the external magnetic field, its gradient, microwave frequency and power can play the role of control parameters for qubit states. Finally, the one and two qubit states decoherence and longitudinal relaxation rate are caused by the interaction of nuclear spins with virtual spin waves in antiferromagnet ground state are calculated.

A. A. Kokin; V. A. Kokin

2008-12-01

180

The Nuclear Structure of ERBIUM-154 at High Spins

NASA Astrophysics Data System (ADS)

The nuclear structure of the ('154)Er nucleus at high spins has been studied by using a heavy-ion fusion -evaporation reaction with an enriched ('124)Te target and a ('34)S-ion beam of 170 Mev bombarding energy. De-excitation gamma rays were detected by using the gamma-gamma coincidence method. Discrete gamma-ray spectra and gamma energy-energy correlation map for the ('154)Er nucleus were obtained. Present results are compared with previous work as well as with theoretical calculations. A new decay scheme of ('154)Er are deduced from the present experiment. Besides the new levels with higher spins which have been identified in this new decay scheme, the present results clarify the discrepancies in the level ordering of the decay scheme among previous reports. However, the absence of correlated gamma transitions in the gamma energy-energy correlation map does not support the prediction of superdeformed shapes in the ('154)Er nucleus at high spins. Possible reasons for this are discussed.

Chen, Ching-Yun

181

Low temperature spin glass transition in Gallium ferrite single crystals

NASA Astrophysics Data System (ADS)

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

Mukherjee, Somdutta; Gupta, Rajeev; Garg, Ashish

2012-02-01

182

High-spin nuclear structure studies with radioactive ion beams

Two important developments in the sixties, namely the advent of heavy-ion accelerators and fabrication of Ge detectors, opened the way for the experimental studies of nuclear properties at high angular momentum. Addition of a new degree of freedom, namely spin, made it possible to observe such fascinating phenomena as occurrences and coexistence of a variety of novel shapes, rise, fall and occasionally rebirth of nuclear collectivity, and disappearance of pairing correlations. Today, with the promise of development of radioactive ion beams (RIB) and construction of the third-generation Ge-detection systems (GAMMASPHERE and EUROBALL), the authors are poised to explore new and equally fascinating phenomena that have been hitherto inaccessible. With the addition of yet another dimension, namely the isospin, they will be able to observe and verify predictions for exotic shapes as varied as rigid triaxiality, hyperdeformation and triaxial octupole shapes, or to investigate the T = 0 pairing correlations. In this paper, they shall review, separately for neutron-deficient and neutron-rich nuclei, these and a few other new high-spin physics opportunities that may be realized with RIB. Following this discussion, they shall present a list of the beam species, intensities and energies that are needed to fulfill these goals. The paper will conclude with a description of the experimental techniques and instrumentations that are required for these studies.

Baktash, C.

1992-12-31

183

Study of thermally induced spin state transition in NdCoO3 single crystal

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

184

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

Paula R. L. Heron

1995-01-01

185

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

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

Ian Harry; Stephen Fairhurst

2011-01-07

186

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

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

Andrei Afanasev; C. E. Carlson

2003-05-01

187

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

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

Dian-Yong Chen; Yu-Bing Dong

2009-11-26

188

Single cell elemental analysis using nuclear microscopy

NASA Astrophysics Data System (ADS)

The use of Particle Induced X-ray Emission (PIXE), Rutherford Backscattering Spectrometry (RBS) and Scanning Transmission Ion Microscopy (STIM) to provide quantitative elemental analysis of single cells is an area which has high potential, particularly when the trace elements such as Ca, Fe, Zn and Cu can be monitored. We describe the methodology of sample preparation for two cell types, the procedures of cell imaging using STIM, and the quantitative elemental analysis of single cells using RBS and PIXE. Recent work on single cells at the Nuclear Microscopy Research Centre,National University of Singapore has centred around two research areas: (a) Apoptosis (programmed cell death), which has been recently implicated in a wide range of pathological conditions such as cancer, Parkinson's disease etc, and (b) Malaria (infection of red blood cells by the malaria parasite). Firstly we present results on the elemental analysis of human Chang liver cells (ATTCC CCL 13) where vanadium ions were used to trigger apoptosis, and demonstrate that nuclear microscopy has the capability of monitoring vanadium loading within individual cells. Secondly we present the results of elemental changes taking place in individual mouse red blood cells which have been infected with the malaria parasite and treated with the anti-malaria drug Qinghaosu (QHS).

Ren, M. Q.; Thong, P. S. P.; Kara, U.; Watt, F.

1999-04-01

189

Nuclear spin structure in dark matter search: The finite momentum transfer limit

Spin-dependent elastic scattering of weakly interacting massive dark matter particles (WIMP) off nuclei is reviewed. All available, within different nuclear models, structure functions S(q) for finite momentum transfer (q>0) are presented. These functions describe the recoil energy dependence of the differential event rate due to the spin-dependent WIMP-nucleon interactions. This paper, together with the previous paper ``Nuclear spin structure in dark matter search: The zero momentum transfer limit'', completes our review of the nuclear spin structure calculations involved in the problem of direct dark matter search.

V. A. Bednyakov; F. Simkovic

2006-08-09

190

Manipulation of nuclear spin dynamics in n-GaAs using an on-chip microcoil

NASA Astrophysics Data System (ADS)

We present an approach for electrically manipulating nuclear spins in n-GaAs using an on-chip microcoil. Optically injected spin-polarized electrons are used to generate a dynamic nuclear polarization via electron-nucleus hyperfine interaction with a characteristic time constant of ˜10 min. The saturated Overhauser field amplitude is on the order of several 10 mT and proportional to the spin polarization degree of the injected electrons. Applying an rf field resonant for the A75s nuclei, complete depolarization of A75s nuclear spins is observed.

Chen, Y. S.; Huang, J.; Ludwig, A.; Reuter, D.; Wieck, A. D.; Bacher, G.

2011-01-01

191

Nuclear spin selection rules in chemical reactions by angular momentum algebra

Nuclear spin selection rules in chemical reactions by angular momentum algebra Takeshi Oka by Quack using molecular symmetry group are derived by using angu- lar momentum algebra. Instead: Selection rules; Nuclear spin modifications; Angular momentum algebra; Ion-neutral reactions; Molecular ions

Oka, Takeshi

192

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

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

2013-10-31

193

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

NASA Astrophysics Data System (ADS)

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

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

2007-06-01

194

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

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

H. Dimov; R. C. Rashkov

2007-09-26

195

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

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

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

2012-09-12

196

Nuclear spin scissors - new type of collective motion

NASA Astrophysics Data System (ADS)

The coupled dynamics of the orbital and spin scissors modes is studied with the help of the Wigner Function Moments method on the basis of Time Dependent Hartree-Fock equations in the harmonic oscillator model including spin orbit potential plus quadrupole- quadrupole and spin-spin residual interactions. The relation between our results and the recent experimental data is discussed.

Balbutsev, E. B.; Molodtsova, I. V.

2014-09-01

197

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

198

Room-temperature solid-state quantum memory using pairs of nuclear spins in diamond

NASA Astrophysics Data System (ADS)

We propose a robust, room-temperature solid-state quantum memory scheme using a pair of nuclear spin impurities in diamond. The memory qubit is encoded in a decoherence-free subspace of this nuclear spin pair, which protects it from noise originating from the surrounding environment. In addition, nuclear spins close to a Nitrogen-Vacancy (NV) color center experience a significant electron-mediated coupling, which further suppresses decoherence of the qubit. We obtain coherence times on the order of a second, along with fast manipulation and readout through the coupling of the nuclear spins to the NV electronic spin. We show that through engineering of the diamond sample this scheme could offer scalability to a many-qubit memory, and could be used as a basic building block for hybrid quantum networks and quantum computing architectures.

Bar-Gill, Nir; Devience, Stephen; Le Sage, David; Belthangady, Chinmay; Pham, Linh; Walsworth, Ronald

2012-02-01

199

Active nuclear spin maser oscillation with double cell

NASA Astrophysics Data System (ADS)

Uncertainty in the frequency precision of the planned experiment to search for a 129Xe atomic electric dipole moment is dominated by drifts in the frequency shift due to contact interaction of 129Xe with polarized Rb valence electrons. In order to suppress the frequency shift, a double-cell geometry has been adopted for the confinement of 129Xe gas. A new process has been identified to take part in the optical detection of spin precession. The parameters controlling the oscillation of the maser in this new double-cell arrangement were optimized. As a result, the frequency shift has been reduced by a factor of 10 or more from the former single-cell geometry.

Hikota, E.; Chikamori, M.; Ichikawa, Y.; Ohtomo, Y.; Sakamoto, Y.; Suzuki, T.; Bidinosti, C. P.; Inoue, T.; Furukawa, T.; Yoshimi, A.; Suzuki, K.; Nanao, T.; Miyatake, H.; Tsuchiya, M.; Yoshida, N.; Shirai, H.; Ino, T.; Ueno, H.; Matsuo, Y.; Fukuyama, T.; Asahi, K.

2014-03-01

200

Cooling a magnetic resonance force microscope via the dynamical back action of nuclear spins

NASA Astrophysics Data System (ADS)

We analyze the back-action influence of nuclear spins on the motion of the cantilever of a magnetic force resonance microscope. We calculate the contribution of nuclear spins to the damping and frequency shift of the cantilever. We show that, at the Rabi frequency, the energy exchange between the cantilever and the spin system cools or heats the cantilever depending on the sign of the high-frequency detuning. We also show that the spin noise leads to a significant damping of the cantilever motion.

Greenberg, Ya. S.; Il'Ichev, E.; Nori, Franco

2009-12-01

201

Optical-coupling nuclear spin maser under highly stabilized low static field

NASA Astrophysics Data System (ADS)

A nuclear spin maser of a new type, that employs a feedback scheme based on optical nuclear spin detection, has been fabricated. The spin maser is operated at a low static field of 30 mG by using the optical detection method. The frequency stability and precision of the spin maser have been improved by a highly stabilized current source for the static magnetic field. An experimental setup to search for an electric dipole moment (EDM) in 129Xe atom is being developed.

Yoshimi, A.; Inoue, T.; Uchida, M.; Hatakeyama, N.; Asahi, K.

2008-01-01

202

Optical-coupling nuclear spin maser under highly stabilized low static field

NASA Astrophysics Data System (ADS)

A nuclear spin maser of a new type, that employs a feedback scheme based on optical nuclear spin detection, has been fabricated. The spin maser is operated at a low static field of 30 mG by using the optical detection method. The frequency stability and precision of the spin maser have been improved by a highly stabilized current source for the static magnetic field. An experimental setup to search for an electric dipole moment (EDM) in 129Xe atom is being developed.

Yoshimi, A.; Inoue, T.; Uchida, M.; Uatakeyama, N.; Asahi, K.

203

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

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

2010-07-28

204

We investigate the electron spin degree of freedom at the imbalanced density bilayer ? = 1 quantum Hall states using the resistively detected nuclear-spin-lattice relaxation rate 1/T{sub 1}. Our measurements reveal a continuous change in 1/T{sub 1} for ? = 1 to 0, suggesting that the balanced density ? = 1 state also exhibits electron-spin fluctuations. Moreover, the value of 1/T{sub 1} in the back layer (the layer from which electrons are transferred to the front layer) increases at intermediate density imbalance states. This indicates that the low-energy electron-spin mode, similar to a mode observed in Skyrmion crystals, might extend across the two layers.

Tsuda, S.; Nguyen, M. H. [Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Terasawa, D.; Fukuda, A. [Department of Physics, Hyogo College of Medicine, Nishinomiya 663-8501 (Japan); Zheng, Y. D.; Arai, T.; Sawada, A. [Research Center for Low Temperatures and Materials Sciences, Kyoto University, Kyoto 606-8501 (Japan); Ezawa, Z. F. [Advanced Meson Science Laboratory, Riken, Wako 980-8578 (Japan)

2013-12-04

205

Single-spin asymmetries in inclusive DIS and in hadronic collisions

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

206

NASA Astrophysics Data System (ADS)

The idea of quantum computation is the most promising recent development in the high-tech domain, while experimental realization of a quantum computer poses a formidable challenge. Among the proposed models especially attractive are semiconductor based nuclear spin quantum computers (S-NSQCs), where nuclear spins are used as quantum bistable elements, `qubits', coupled to the electron spin and orbital dynamics. We propose here a scheme for implementation of basic elements for S-NSQCs which are realizable within achievements of the modern nanotechnology. These elements are expected to be based on a nuclear-spin-controlled isotopically engineered Si/SiGe heterojunction, because in these semiconductors one can vary the abundance of nuclear spins by engineering the isotopic composition. A specific device is suggested, which allows one to model the processes of recording, reading and information transfer on a quantum level using the technique of electrical detection of the magnetic state of nuclear spins. Improvement of this technique for a semiconductor system with a relatively small number of nuclei might be applied to the manipulation of nuclear spin `qubits' in the future S-NSQCs.

Shlimak, I.; Safarov, V. I.; Vagner, I. D.

2001-07-01

207

Conditional Control of Donor Nuclear Spins in Silicon Using Stark Shifts

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

208

Long-lived nuclear spin states could greatly enhance the applicability of hyperpolarized nuclear magnetic resonance. Using singlet states between inequivalent spin pairs has been shown to extend the signal lifetime by more than an order of magnitude compared to the spin lattice relaxation time (T1), but they have to be prevented from evolving into other states. In the most interesting case the singlet is between chemically equivalent spins, as it can then be inherently an eigenstate. However this presents major challenges in the conversion from bulk magnetization to singlet. In the only case demonstrated so far, a reversible chemical reaction to break symmetry was required. Here we present a pulse sequence technique that interconverts between singlet spin order and bulk magnetization without breaking the symmetry of the spin system. This technique is independent of field strength and is applicable to a broad range of molecules. PMID:23505397

Feng, Yesu; Davis, Ryan M.; Warren, Warren S.

2013-01-01

209

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

NASA Astrophysics Data System (ADS)

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

Zhou, Jian

2014-04-01

210

NMR quantum computing with qubit systems represented by nuclear spins (I=12) in small molecules in liquids has led to the most successful experimental quantum information processors so far. We use the quadrupolar spin-32 sodium nuclei of a NaNO3 single crystal as a virtual two-qubit system. The large quadrupolar coupling in comparison with the environmental interactions and the usage of strongly modulating pulses allow us to manipulate the system fast enough and at the same time keeping the decoherence reasonably slow. The experimental challenge is to characterize the "calculation" behavior of the quantum processor by process tomography which is here adapted to the quadrupolar spin system. The results of a selection of quantum gates and algorithms are presented as well as a detailed analysis of experimental results. PMID:15974729

Kampermann, H; Veeman, W S

2005-06-01

211

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

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

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

2013-11-04

212

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

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

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

2012-01-15

213

The Study of High Spin States in Nuclear Rotation by the Cranked Nilsson Strutinsky Model

A heavy-ion reaction can populate nuclear states of very high angular momentum with values of the order of I = 60 achievable. The reaction produces such configurations with a considerable internal excitation, but the emission of a few neutrons reduces the excitation energy effectively while not decreasing the spin by much. At sufficiently high spin the pairing is destroyed completely and the rigid-body moment of inertia becomes a good approximation. Even in this regime, however, the single-particle structure remains important and shell effects can be studied in terms of a rotating phenomenological shell model. On the theoretical side the cranked Nilsson strutinsky model has proved to be a successful tool to describe rapidly rotating nucleus. Indeed, this model gives a microscopic description of the influence of rotation on single-particle motion. This paper will concentrate on introduction to the cranked Nilsson strutinsky model in details. First, we explain the cranking model and the rotating liquid-drop model, then introduce the shell correction method. Also, we describe terminating bands, which show a continuous transition from high collectivity to a pure particle-hole state.

Kardan, A.; Miri-Hakimabad, H.; Rafat-Motevalli, L. [Physics Department, Faculty of Science, Ferdowsi University of Mashhad, P. O. Box 91775-1436, Mashhad (Iran, Islamic Republic of)

2010-11-24

214

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

215

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

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

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

2013-01-01

216

Cryogenic sample exchange NMR probe for magic angle spinning dynamic nuclear polarization

We describe a cryogenic sample exchange system that dramatically improves the efficiency of magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments by reducing the time required to change samples and by ...

Barnes, Alexander B.

217

Nuclear-Spin Gyroscope Based on an Atomic Co-Magnetometer

NASA Technical Reports Server (NTRS)

An experimental nuclear-spin gyroscope is based on an alkali-metal/noblegas co-magnetometer, which automatically cancels the effects of magnetic fields. Whereas the performances of prior nuclear-spin gyroscopes are limited by sensitivity to magnetic fields, this gyroscope is insensitive to magnetic fields and to other external perturbations. In addition, relative to prior nuclear-spin gyroscopes, this one exhibits greater sensitivity to rotation. There is commercial interest in development of small, highly sensitive gyroscopes. The present experimental device could be a prototype for development of nuclear spin gyroscopes suitable for navigation. In comparison with fiber-optic gyroscopes, these gyroscopes would draw less power and would be smaller, lighter, more sensitive, and less costly.

Romalis, Michael; Komack, Tom; Ghost, Rajat

2008-01-01

218

Nuclear Spin Gyroscope Based on an Atomic Comagnetometer T. W. Kornack, R. K. Ghosh, and M. V; published 29 November 2005) We describe a nuclear spin gyroscope based on an alkali their gyroscopic precession. Spin precession due to magnetic fields as well as their gradients and transients can

Romalis, Mike

219

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

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

220

Description of ^{158}Er at Ultrahigh Spin in Nuclear Density Functional Theory

Rotational bands in 158Er at ultrahigh spin have been studied in the framework of relativistic and nonrelativistic nuclear density-functional theories. Consistent results are obtained across the theoretical models used but some puzzles remain when confronted with experiment. Namely, the many-body configurations which provide good description of experimental transition quadrupole moments and dynamic moments of inertia require substantial increase of the spins of observed bands as compared with experimental estimates, which are still subject to large uncertainties. If, however, the theoretical spin assignments turned out to be correct, experimental band 1 in 158Er would be the highest spin structure ever observed.

Afanasjev, A. V. [Mississippi State University/JIHIR, ORNL; Shi, Yue [Peking University; Nazarewicz, Witold [UTK/ORNL/University of Warsaw

2012-01-01

221

Search for electric dipole moment in 129Xe atom using active nuclear spin maser

NASA Astrophysics Data System (ADS)

An experimental search for an electric dipole moment in the diamagnetic atom 129Xe is in progress through the precision measurement of spin precession frequency using an active nuclear spin maser. A 3He comagnetometer has been incorporated into the active spin maser system in order to cancel out the long-term drifts in the external magnetic field. Also, a double-cell geometry has been adopted in order to suppress the frequency shifts due to interaction with polarized Rb atoms. The first EDM measurement with the 129Xe active spin maser and the 3He comagnetometer has been conducted.

Ichikawa, Y.; Chikamori, M.; Ohtomo, Y.; Hikota, E.; Sakamoto, Y.; Suzuki, T.; Bidinosti, C. P.; Inoue, T.; Furukawa, T.; Yoshimi, A.; Suzuki, K.; Nanao, T.; Miyatake, H.; Tsuchiya, M.; Yoshida, N.; Shirai, H.; Ino, T.; Ueno, H.; Matsuo, Y.; Fukuyama, T.; Asahi, K.

2014-03-01

222

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

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

2014-11-12

223

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

224

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

225

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

226

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

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

Goan, Hsi-Sheng

227

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

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

Loss, Daniel

228

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

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

Loss, Daniel

229

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

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

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

1996-01-01

230

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

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

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

1996-01-01

231

Search for electric dipole moment in 129Xe atom using a nuclear spin oscillator

NASA Astrophysics Data System (ADS)

We aim to measure the electric dipole moment (EDM) of a diamagnetic atom 129Xe using an optical-detection nuclear spin maser technique. The relation of EDM in a diamagnetic atom to nuclear Schiff moment and fundamental sources generating it is discussed, and the present status for the development of our experimental setup is presented.

Asahi, K.; Ichikawa, Y.; Chikamori, M.; Ohtomo, Y.; Hikota, E.; Suzuki, T.; Inoue, T.; Furukawa, T.; Yoshimi, A.; Suzuki, K.; Nanao, T.; Miyatake, H.; Tsuchiya, M.; Yoshida, N.; Shirai, H.; Ino, T.; Ueno, H.; Matsuo, Y.; Fukuyama, T.

2014-01-01

232

Sensitizing solid state nuclear magnetic resonance of dilute nuclei by spin- diffusion assisted polarization transfers Adonis Lupulescu and Lucio Frydman Citation: J. Chem. Phys. 135, 134202 (2011); doi: 10://jcp.aip.org/about/rights_and_permissions #12;THE JOURNAL OF CHEMICAL PHYSICS 135, 134202 (2011) Sensitizing solid state nuclear magnetic

Frydman, Lucio

233

Spin-asymmetry energy of nuclear matter N. Kaiser Physik-Department T39, Technische UniversitÃ¤t the density-dependent spin-asymmetry energy S kf of isospin-symmetric nuclear matter in the three of freedom in the description of the nuclear many- body dynamics. The contributions to the energy per

Weise, Wolfram

234

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

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

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

2011-12-15

235

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

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

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

2010-01-29

236

Optimal spin-state transition in singly occupied quantum dots network

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

237

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

We generalize the method of our recent paper on large-spin expansions of Gubser-Klebanov-Polyakov (GKP) strings to the large-spin and large-winding expansions of finite-size giant magnons and finite-size single spikes. By expressing the energies of long open strings in RxS2 in terms of Lambert's W-function, we compute the leading, subleading and next-to-subleading series of classical exponential corrections to the dispersion relations of Hofman-Maldacena giant magnons and infinite-winding single spikes. We also compute the corresponding expansions in the doubled regions of giant magnons and single spikes that are respectively obtained when their angular and linear velocities become smaller or greater than unity.

Emmanuel Floratos; Georgios Linardopoulos

2014-06-03

238

NASA Astrophysics Data System (ADS)

We report solid state 13C and 1H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, 1H and cross-polarized 13C NMR signals from 15N,13C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T1e is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations.

Thurber, Kent R.; Tycko, Robert

2014-05-01

239

We report solid state (13)C and (1)H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, (1)H and cross-polarized (13)C NMR signals from (15)N,(13)C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T1e is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations. PMID:24832263

Thurber, Kent R; Tycko, Robert

2014-05-14

240

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

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

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

2011-01-01

241

Single-particle resonances in continuum nuclear structure calculations

Accuracy and stability of single-particle resonance parameters under changes of a resonance wave function'' are examined in the context of a projection technique. Implications for their use in nuclear structure calculations are discussed.

Teruya, N.; de Toledo Piza, A.F.R.; Dias, H. (Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 20516, 01498 Sao Paulo, SP, Brazil (BR))

1991-07-01

242

A range of aluminate sodalites of general formula M8(AlO2)12.X2, where M and X are a divalent cation and anion, respectively, has been synthesised. The structures of these materials, which contain a single aluminum environment, have been refined from powder X-ray or neutron diffraction data and the compounds further characterised using 27Al magic-angle spinning nuclear magnetic resonance (MAS NMR). Correlations between (i) the Al-O-Al bond angles and the 27Al chemical shift and (ii) the quadrupolar coupling constant and the distorted AlO4 tetrahedral geometry have been determined. PMID:7834310

Weller, M T; Brenchley, M E; Apperley, D C; Davies, N A

1994-04-01

243

Nuclear magnetic moments and the spin-orbit current in the relativistic mean field theory

The Dirac magnetic moments in the relativistic mean field theory are affected not only by the effective mass, but also by the spin-orbit current related to the spin-orbit force through the continuity equation. Previous arguments on the cancellation of the effective-mass effect in nuclear matter are not simply applied to finite nuclei to obtain the Schmidt values. Effects of the

Shigeru Nishizaki; Haruki Kurasawa; Toshio Suzuki

1988-01-01

244

Nuclear spin structure in dark matter search: The zero momentum transfer limit

We review the calculation of spin-dependent matrix elements relevant to\\u000ascattering of weakly interacting massive particles on nuclei. A comprehensive\\u000alist, to our knowledge, of the proton and neutron total spin expectation values\\u000a($<{\\\\bf S}_{p}>$ and $<{\\\\bf S}_{n}>$) calculated within different nuclear\\u000amodels is presented. These values allow a conclusion about the event rate\\u000aexpected in direct dark matter search

V. A. Bednyakov; F. Simkovic

2004-01-01

245

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

NASA Astrophysics Data System (ADS)

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

Nossa, Javier; Canali, Carlo

2013-03-01

246

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

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

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

2012-08-29

247

Effect of electron spin dynamics on solid-state dynamic nuclear polarization performance.

For the broadest dissemination of solid-state dynamic nuclear polarization (ssDNP) enhanced NMR as a material characterization tool, the ability to employ generic mono-nitroxide radicals as spin probes is critical. A better understanding of the factors contributing to ssDNP efficiency is needed to rationally optimize the experimental condition for the practically accessible spin probes at hand. This study seeks to advance the mechanistic understanding of ssDNP by examining the effect of electron spin dynamics on ssDNP performance at liquid helium temperatures (4-40 K). The key observation is that bi-radicals and mono-radicals can generate comparable nuclear spin polarization at 4 K and 7 T, which is in contrast to the observation for ssDNP at liquid nitrogen temperatures (80-150 K) that finds bi-radicals to clearly outperform mono-radicals. To rationalize this observation, we analyze the change in the DNP-induced nuclear spin polarization (Pn) and the characteristic ssDNP signal buildup time as a function of electron spin relaxation rates that are modulated by the mono- and bi-radical spin concentration. Changes in Pn are consistent with a systematic variation in the product of the electron spin-lattice relaxation time and the electron spin flip-flop rate that constitutes an integral saturation factor of an inhomogeneously broadened EPR spectrum. We show that the comparable Pn achieved with both radical species can be reconciled with a comparable integral EPR saturation factor. Surprisingly, the largest Pn is observed at an intermediate spin concentration for both mono- and bi-radicals. At the highest radical concentration, the stronger inter-electron spin dipolar coupling favors ssDNP, while oversaturation diminishes Pn, as experimentally verified by the observation of a maximum Pn at an intermediate, not the maximum, microwave (?w) power. At the maximum ?w power, oversaturation reduces the electron spin population differential that must be upheld between electron spins that span a frequency difference matching the (1)H NMR frequency-characteristic of the cross effect DNP. This new mechanistic insight allows us to rationalize experimental conditions where generic mono-nitroxide probes can offer competitive ssDNP performance to that of custom designed bi-radicals, and thus helps to vastly expand the application scope of ssDNP for the study of functional materials and solids. PMID:24968276

Siaw, Ting Ann; Fehr, Matthias; Lund, Alicia; Latimer, Allegra; Walker, Shamon A; Edwards, Devin T; Han, Song-I

2014-09-21

248

Magnetic property of a single crystal of spin-1/2 triple-chain magnet Cu3(OH)4SO4

NASA Astrophysics Data System (ADS)

The spin-1/2 triple-chain magnet Cu3(OH)4SO4 (mineral name: antlerite) is a candidate `idlespin' system. In order to study the phase transitions in this compound in detail, we have performed specific-heat measurements under magnetic fields up to 10 T and in the temperature range down to 1.9 K and proton nuclear magnetic resonance (1H-NMR) experiments with single crystals. We found at least three successive phase transitions at zero field around 5 K which strongly depend on the value and the direction of the applied field. Another transition around 3 K was also found. 1H-NMR spectra in a low-temperature and low-field ordered phase indicated an antiferromagnetic commensurate spin structure with at least four sublattices, which is discussed in connection with the idle-spin state. Phase diagrams show a richness of magnetic phases for this compound.

Fujii, Yutaka; Ishikawa, Yuya; Kikuchi, Hikomitsu; Narumi, Yasuo; Nojiri, Hiroyuki; Hara, Shigeo; Sato, Hirohiko

2013-06-01

249

be used to hyperpolarize, manipulate and measure two nearby nuclear spins. Implementing a scheme that uses the successful use of a transient electron spin motivates the design of new molecules able to exploitHz. This weak coupling places a lower limit on the duration of a quantum logic operation between two spins

Loss, Daniel

250

We present theoretical calculations of dynamic nuclear polarization (DNP) due to the cross effect in nuclear magnetic resonance under magic-angle spinning (MAS). Using a three-spin model (two electrons and one nucleus), cross effect DNP with MAS for electron spins with a large g-anisotropy can be seen as a series of spin transitions at avoided crossings of the energy levels, with varying degrees of adiabaticity. If the electron spin-lattice relaxation time T1e is large relative to the MAS rotation period, the cross effect can happen as two separate events: (i) partial saturation of one electron spin by the applied microwaves as one electron spin resonance (ESR) frequency crosses the microwave frequency and (ii) flip of all three spins, when the difference of the two ESR frequencies crosses the nuclear frequency, which transfers polarization to the nuclear spin if the two electron spins have different polarizations. In addition, adiabatic level crossings at which the two ESR frequencies become equal serve to maintain non-uniform saturation across the ESR line. We present analytical results based on the Landau-Zener theory of adiabatic transitions, as well as numerical quantum mechanical calculations for the evolution of the time-dependent three-spin system. These calculations provide insight into the dependence of cross effect DNP on various experimental parameters, including MAS frequency, microwave field strength, spin relaxation rates, hyperfine and electron-electron dipole coupling strengths, and the nature of the biradical dopants. PMID:22938251

Thurber, Kent R.; Tycko, Robert

2012-01-01

251

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

252

Taking into account more accurately the isospin dependence of nucleon-nucleon interactions in the in-medium many-body force term of the Gogny effective interaction, new expressions for the single nucleon potential and the symmetry energy are derived. Effects of both the spin(isospin) and the density dependence of nuclear effective interactions on the symmetry potential and the symmetry energy are examined. It is shown that they both play a crucial role in determining the symmetry potential and the symmetry energy at supra-saturation densities. The improved single nucleon potential will be useful for simulating more accurately nuclear reactions induced by rare isotope beams within transport models.

Chang Xu; Bao-An Li

2010-03-08

253

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

254

Simultaneous sub-second hyperpolarization of the nuclear and electron spins of phosphorus in silicon

We demonstrate a method which can hyperpolarize both the electron and nuclear spins of 31P donors in Si at low field, where both would be essentially unpolarized in equilibrium. It is based on the selective ionization of donors in a specific hyperfine state by optically pumping donor bound exciton hyperfine transitions, which can be spectrally resolved in 28Si. Electron and nuclear polarizations of 90% and 76%, respectively, are obtained in less than a second, providing an initialization mechanism for qubits based on these spins, and enabling further ESR and NMR studies on dilute 31P in 28Si.

A. Yang; M. Steger; T. Sekiguchi; M. L. W. Thewalt; T. D. Ladd; K. M. Itoh; H. Riemann; N. V. Abrosimov; P. Becker; H. -J. Pohl

2009-03-09

255

Simultaneous sub-second hyperpolarization of the nuclear and electron spins of phosphorus in silicon

We demonstrate a method which can hyperpolarize both the electron and nuclear spins of 31P donors in Si at low field, where both would be essentially unpolarized in equilibrium. It is based on the selective ionization of donors in a specific hyperfine state by optically pumping donor bound exciton hyperfine transitions, which can be spectrally resolved in 28Si. Electron and nuclear polarizations of 90% and 76%, respectively, are obtained in less than a second, providing an initialization mechanism for qubits based on these spins, and enabling further ESR and NMR studies on dilute 31P in 28Si.

Yang, A; Sekiguchi, T; Thewalt, M L W; Ladd, T D; Itoh, K M; Riemann, H; Abrosimov, N V; Becker, P; Pohl, H -J

2009-01-01

256

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

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

2014-10-02

257

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

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

2014-01-01

258

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

259

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

NASA Astrophysics Data System (ADS)

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

Prabhakar, Sanjay; Raynolds, James

2008-03-01

260

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

261

Improving Estimates of Nuclear-Spin Relaxation Time (T1) in Surface-NMR Experiments

NASA Astrophysics Data System (ADS)

Surface nuclear magnetic resonance (NMR) is a relatively novel and powerful geophysical technique for investigating hydrological characteristics of shallow aquifers from the Earth's surface in a non-invasive way. Large current loops of approximately 100 m diameter laid on the ground transmit electromagnetic pulses into the subsurface. These pulses excite spins of protons in groundwater molecules out of their equilibrium state in the Earth's magnetic field. The spin response is recorded on either coincident or offset surface receiver loops of similar dimension. The amplitudes of the response signals recorded after single-pulse excitation provide estimates of water-content in the shallow subsurface. Another important parameter is the NMR relaxation time T1, from which information on pore structure or even hydraulic conductivity can be inferred under favorable circumstances. T1 data are conventionally acquired using a scheme that involves two sequential pulses of electromagnetic energy, the second of which is phase-shifted by ? relative to the first. We show that common imperfections in the transmitted pulses and variations of the excitation field with distance from the transmitter introduce significant bias in conventional estimates of T1. Here, we propose a novel yet simple modification to the conventional scheme that is theoretically capable of resolving this problem. The proposed scheme comprises a conventional double-pulse sequence followed by an additional double-pulse sequence for which the 2nd pulse is in-phase with the 1st pulse. Subtracting the voltage signals measured during the two double-pulse sequences (i.e., phase cycle) eliminates the bias. This strategy of continuously cycling the phase of the 2nd pulse between ? and 0 in sequential double-pulse experiments and then subtracting the resulting voltages is a promising step towards recording more reliable T1 data under general field conditions.

Walbrecker, Jan O.; Hertrich, Marian; Green, Alan G.

2011-03-01

262

Microwave Field Distribution in a Magic Angle Spinning Dynamic Nuclear Polarization NMR Probe

We present a calculation of the microwave field distribution in a magic angle spinning (MAS) probe utilized in dynamic nuclear polarization (DNP) experiments. The microwave magnetic field (B1S) profile was obtained from simulations performed with the High Frequency Structure Simulator (HFSS) software suite, using a model that includes the launching antenna, the outer Kel-F stator housing coated with Ag, the RF coil, and the 4 mm diameter sapphire rotor containing the sample. The predicted average B1S field is 13µT/W1/2, where S denotes the electron spin. For a routinely achievable input power of 5 W the corresponding value is ? SB1S = 0.84 MHz. The calculations provide insights into the coupling of the microwave power to the sample, including reflections from the RF coil and diffraction of the power transmitted through the coil. The variation of enhancement with rotor wall thickness was also successfully simulated. A second, simplified calculation was performed using a single pass model based on Gaussian beam propagation and Fresnel diffraction. This model provided additional physical insight and was in good agreement with the full HFSS simulation. These calculations indicate approaches to increasing the coupling of the microwave power to the sample, including the use of a converging lens and fine adjustment of the spacing of the windings of the RF coil. The present results should prove useful in optimizing the coupling of microwave power to the sample in future DNP experiments. Finally, the results of the simulation were used to predict the cross effect DNP enhancement (?) vs. ?1S/(2?) for a sample of 13C-urea dissolved in a 60:40 glycerol/water mixture containing the polarizing agent TOTAPOL; very good agreement was obtained between theory and experiment. PMID:21382733

Nanni, Emilio A.; Barnes, Alexander B.; Matsuki, Yoh; Woskov, Paul P.; Corzilius, Bjorn; Griffin, Robert G.; Temkin, Richard J.

2011-01-01

263

Anomalous nuclear spin relaxation of adsorbed helium-3

Within the framework of a general theory of two-dimensional NMR we are able to elucidate certain anomalous features of spin relaxation in adsorbed and porous systems. We explain the linear dependence of relaxation time on applied magnetic field, and this is demonstrated to be related to the relative insensitivity ofT1to temperature. We also show thatT1remains field dependent on the “fast”

Brian P. Cowan

1983-01-01

264

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

Flatte, Michael E.

265

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

266

these couplings for its spin-flip variant for the first time. Our algorithm is closely related to the CIS analytic energy gradient algorithm and should be straightforward to implement in any quantum chemistry code-flip configuration interaction singles and spin-flip time-dependent density functional theory Xing Zhang and John M

Herbert, John

267

Nuclear-Powered Millisecond Pulsars and the Maximum Spin Frequency of Neutron Stars

Millisecond pulsars are neutron stars (NSs) that are thought to have been spun-up by mass accretion from a stellar companion. It is unknown whether there is a natural brake for this process, or if it continues until the centrifugal breakup limit is reached at submillisecond periods. Many NSs that are accreting from a companion exhibit thermonuclear X-ray bursts that last tens of seconds, caused by unstable nuclear burning on their surfaces. Millisecond brightness oscillations during bursts from ten NSs (as distinct from other rapid X-ray variability that is also observed) are thought to measure the stellar spin, but direct proof of a rotational origin has been lacking. Here, we report the detection of burst oscillations at the known spin frequency of an accreting millisecond pulsar, and we show that these oscillations always have the same rotational phase. This firmly establishes burst oscillations as nuclear-powered pulsations tracing the spin of accreting NSs, corroborating earlier evidence. The distribution of spin frequencies of the 11 nuclear-powered pulsars cuts off well below the breakup frequency for most NS models, supporting theoretical predictions that gravitational radiation losses can limit accretion torques in spinning up millisecond pulsars.

Deepto Chakrabarty; Edward H. Morgan; Michael P. Muno; Duncan K. Galloway; Rudy Wijnands; Michiel van der Klis; Craig B. Markwardt

2003-07-01

268

Role of dual nuclear baths on spin blockade leakage current bistabilities.

Spin-blockaded electronic transport across a double quantum dot (DQD) system represents an important advancement in the area of spin-based quantum information. The basic mechanism underlying the blockade is the formation of a blocking triplet state. The bistability of the leakage current as a function of the applied magnetic field in this regime is believed to arise from the effect of nuclear Overhauser fields on spin-flip transitions between the blocking triplet and the conducting singlet states. The objective of this paper is to present the nuances of considering a two bath model on the experimentally observed current bistability by employing a self consistent simulation of the nuclear spin dynamics coupled with the electronic transport of the DQD set up. In doing so, we first discuss the important subtleties involved in the microscopic derivation of the hyperfine mediated spin flip rates. We then give insights as to how the differences between the two nuclear baths and the resulting difference Overhauser field affect the two-electron states of the DQD and their connection with the experimentally observed current hysteresis curve. PMID:25374371

Buddhiraju, Siddharth; Muralidharan, Bhaskaran

2014-12-01

269

Spin excitations in a single La2CuO4 layer.

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

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

2012-10-01

270

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

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

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

2013-12-16

271

In this paper, we calculate properties of the spin polarized asymmetrical nuclear matter and neutron star matter, using the lowest order constrained variational (LOCV) method with the AV{sub 18}, Reid93, UV{sub 14}, and AV{sub 14} potentials. According to our results, the spontaneous phase transition to a ferromagnetic state in the asymmetrical nuclear matter as well as neutron star matter do not occur.

Bordbar, G. H. [Department of Physics, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha, P. O. Box 55134-441, Maragha (Iran, Islamic Republic of); Bigdeli, M. [Department of Physics, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Department of Physics, Zanjan University, Zanjan (Iran, Islamic Republic of)

2008-01-15

272

The role of level anti-crossings in nuclear spin hyperpolarization.

Nuclear spin hyperpolarization is an important resource for increasing the sensitivity of NMR spectroscopy and MRI. Signal enhancements can be as large as 3-4 orders of magnitude. In hyperpolarization experiments, it is often desirable to transfer the initial polarization to other nuclei of choice, either protons or insensitive nuclei such as (13)C and (15)N. This situation arises primarily in Chemically Induced Dynamic Nuclear Polarization (CIDNP), Para-Hydrogen Induced Polarization (PHIP), and the related Signal Amplification By Reversible Exchange (SABRE). Here we review the recent literature on polarization transfer mechanisms, in particular focusing on the role of Level Anti-Crossings (LACs) therein. So-called "spontaneous" polarization transfer may occur both at low and high magnetic fields. In addition, transfer of spin polarization can be accomplished by using especially designed pulse sequences. It is now clear that at low field spontaneous polarization transfer is primarily due to coherent spin-state mixing under strong coupling conditions. However, thus far the important role of LACs in this process has not received much attention. At high magnetic field, polarization may be transferred by cross-relaxation effects. Another promising high-field technique is to generate the strong coupling condition by spin locking using strong radio-frequency fields. Here, an analysis of polarization transfer in terms of LACs in the rotating frame is very useful to predict which spin orders are transferred depending on the strength and frequency of the B1 field. Finally, we will examine the role of strong coupling and LACs in magnetic-field dependent nuclear spin relaxation and the related topic of long-lived spin-states. PMID:25142733

Ivanov, Konstantin L; Pravdivtsev, Andrey N; Yurkovskaya, Alexandra V; Vieth, Hans-Martin; Kaptein, Robert

2014-08-01

273

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

Allada, Kalyan C.

274

Pulsed Gradient Spin Echo Nuclear Magnetic Resonance Imaging of Diffusion in Granular Flow

We derive the formalism to obtain spatial distributions of collisional correlation times for macroscopic particles undergoing granular flow from pulsed gradient spin echo nuclear magnetic resonance diffusion data. This is demonstrated with an example of axial motion in the shear flow regime of a 3D granular flow in a horizontal rotating cylinder at one rotation rate.

Joseph D. Seymour; Arvind Caprihan; Stephen A. Altobelli; Eiichi Fukushima

2000-01-01

275

Pulsed Gradient Spin Echo Nuclear Magnetic Resonance Imaging of Diffusion in Granular Flow

We derive the formalism to obtain spatial distributions of collisional correlation times for macroscopic particles undergoing granular flow from pulsed gradient spin echo nuclear magnetic resonance diffusion data. This is demonstrated with an example of axial motion in the shear flow regime of a 3D granular flow in a horizontal rotating cylinder at one rotation rate. (c) 2000 The American

Joseph D. Seymour; Arvind Caprihan; Stephen A. Altobelli; Eiichi Fukushima

2000-01-01

276

Nuclear spin relaxation in a vinylidene fluoride and trifluoroethylene copolymer 70/30

563 Nuclear spin relaxation in a vinylidene fluoride and trifluoroethylene copolymer 70/30 I fluoride (PVF2) is known to possess a polar crystalline 3 phase were the chains are in the all of this system have been extensively studied [1]. Recently, it has been shown that vinylidene fluoride

Boyer, Edmond

277

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

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

278

NASA Astrophysics Data System (ADS)

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

Goryca, Mateusz

2010-02-01

279

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

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

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

2014-08-13

280

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

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

Han Liu

2006-12-13

281

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

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

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

2014-01-01

282

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

283

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

Max Fathi; Georg Menz

2014-05-13

284

Spin switching and magnetization reversal in single-crystal NdFeO3

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

285

On a translationally invariant nuclear single particle picture

If one assumes a translationally invariant motion of the nucleons relative to the c. m. position in single particle mean fields a correlated single particle picture of the nuclear wave function emerges. A single particle product ansatz leads for that Hamiltonian to nonlinear equations for the single particle wave functions. In contrast to a standard not translationally invariant shell model picture those single particle s-, p- etc states are coupled. The strength of the resulting coupling is an open question. The Schroedinger equation for that Hamiltonian can be solved by few- and many -body techniques, which will allow to check the validity or non-validity of a single particle product ansatz. Realistic nuclear wave functions exhibit repulsive 2-body short range correlations. Therefore a translationally invariant single particle picture -- if useful at all -- can only be expected beyond those ranges. Since exact A = 3 and 4 nucleon ground state wave functions and beyond based on modern nuclear forces are available, the translationally invariant shell model picture can be optimized by an adjustment to the exact wave function and its validity or non-validity decided.

W. Gloeckle; H. Kamada; J. Golak

2011-06-10

286

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

287

NASA Astrophysics Data System (ADS)

We demonstrate that zero-field ?-detected nuclear quadrupole resonance and spin relaxation of low energy Li8 can be used as a sensitive local probe of structural phase transitions near a surface. We find that the transition near the surface of a SrTiO3 single crystal occurs at Tc˜150K, i.e., ˜45K higher than Tcbulk, and that the tetragonal domains formed below Tc are randomly oriented.

Salman, Z.; Kiefl, R. F.; Chow, K. H.; Hossain, M. D.; Keeler, T. A.; Kreitzman, S. R.; Levy, C. D. P.; Miller, R. I.; Parolin, T. J.; Pearson, M. R.; Saadaoui, H.; Schultz, J. D.; Smadella, M.; Wang, D.; Macfarlane, W. A.

2006-04-01

288

All-optical sensing of a single-molecule electron spin

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

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

2013-01-01

289

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

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

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

2014-03-22

290

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

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

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

2014-11-12

291

All-optical sensing of a single-molecule electron spin

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

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

2013-11-07

292

We revisit the calculation of analytic derivative couplings for configuration interaction singles (CIS), and derive and implement these couplings for its spin-flip variant for the first time. Our algorithm is closely related to the CIS analytic energy gradient algorithm and should be straightforward to implement in any quantum chemistry code that has CIS analytic energy gradients. The additional cost of evaluating the derivative couplings is small in comparison to the cost of evaluating the gradients for the two electronic states in question. Incorporation of an exchange-correlation term provides an ad hoc extension of this formalism to time-dependent density functional theory within the Tamm-Dancoff approximation, without the need to invoke quadratic response theory or evaluate third derivatives of the exchange-correlation functional. Application to several different conical intersections in ethylene demonstrates that minimum-energy crossing points along conical seams can be located at substantially reduced cost when analytic derivative couplings are employed, as compared to use of a branching-plane updating algorithm that does not require these couplings. Application to H3 near its D(3h) geometry demonstrates that correct topology is obtained in the vicinity of a conical intersection involving a degenerate ground state. PMID:25134548

Zhang, Xing; Herbert, John M

2014-08-14

293

Rabi and Larmor nuclear quadrupole double resonance of spin-1 nuclei.

We demonstrate the creation of two novel double-resonance conditions between spin-1 and spin-1/2 nuclei in a crystalline solid. Using a magnetic field oscillating at the spin-1/2 Larmor frequency, the nuclear quadrupole resonance (NQR) frequency is matched to the Rabi or Rabi plus Larmor frequency, as opposed to the Larmor frequency as is conventionally done. We derive expressions for the cross-polarization rate for all three conditions in terms of the relevant secular dipolar Hamiltonian, and demonstrate with these expressions how to measure the strength of the heterogenous dipolar coupling using only low magnetic fields. In addition, the combination of different resonance conditions permits the measurement of the spin-1/2 angular momentum vector using spin-1 NQR, opening up an alternate modality for the monitoring of low-field nuclear magnetic resonance. We use ammonium nitrate to explore these resonance conditions, and furthermore use the oscillating field to increase the signal-to-noise ratio per time by a factor of 3.5 for NQR detection of this substance. PMID:23231223

Prescott, D W; Malone, M W; Douglass, S P; Sauer, K L

2012-12-01

294

Experimental demonstration of stimulated polarization wave in a chain of nuclear spins

NASA Astrophysics Data System (ADS)

A one-dimensional Ising chain irradiated by weak resonant transverse field is the simplest model of quantum amplifier [Phys. Rev. A 71, 062338 (2005)]. The quantum state of the chain is stationary when all the qubits (spins) are in the same state. However, when the first qubit is flipped, it triggers a stimulated wave of flipped qubits, propagating through the chain. Such ``quantum domino" dynamics induces huge change in the total polarization, a macroscopic observable. Here we present the experimental demonstration of this quantum amplification process on a four-qubit system by using nuclear magnetic resonance technique. The physical system is a linear chain of four ^13C nuclear spins in a molecule of fully ^ 13C-labeled sodium butyrate dissolved in D2O. The pseudopure ground state (with all spins up) is prepared by multi-frequency partial saturation. The wave of flipped spins has been clearly observed when the first spin of the chain is flipped. We define a coefficient of amplification as the relative enhancement of the total polarization change. In our experimental system, the measured coefficient of amplification is about 3.

Lee, Jae-Seung; Adams, Travis; Khitrin, Anatoly

2007-03-01

295

Advances and applications of dynamic-angle spinning nuclear magnetic resonance

This dissertation describes nuclear magnetic resonance experiments and theory which have been developed to study quadrupolar nuclei (those nuclei with spin greater than one-half) in the solid state. Primarily, the technique of dynamic-angle spinning (DAS) is extensively reviewed and expanded upon in this thesis. Specifically, the improvement in both the resolution (two-dimensional pure-absorptive phase methods and DAS angle choice) and sensitivity (pulse-sequence development), along with effective spinning speed enhancement (again through choice of DAS conditions or alternative multiple pulse schemes) of dynamic-angle spinning experiment was realized with both theory and experimental examples. The application of DAS to new types of nuclei (specifically the {sup 87}Rb and {sup 85}Rb nuclear spins) and materials (specifically amorphous solids) has also greatly expanded the possibilities of the use of DAS to study a larger range of materials. This dissertation is meant to demonstrate both recent advances and applications of the DAS technique, and by no means represents a comprehensive study of any particular chemical problem.

Baltisberger, J.H.

1993-06-01

296

NASA Astrophysics Data System (ADS)

Resonant cooling of different nuclear isotopes manifested in optically induced nuclear magnetic resonances (NMR) is observed in n-doped CdTe/(Cd,Mg)Te and ZnSe/(Zn,Mg)Se quantum wells and for donor-bound electrons in ZnSe:F and GaAs epilayers. By time-resolved Kerr rotation used in the regime of resonant spin amplification, we can expand the range of magnetic fields where the effect can be observed up to nuclear Larmor frequencies of 170 kHz. The mechanism of the resonant cooling of the nuclear spin system is analyzed theoretically. The developed approach allows us to model the resonant spin amplification signals with NMR features.

Zhukov, E. A.; Greilich, A.; Yakovlev, D. R.; Kavokin, K. V.; Yugova, I. A.; Yugov, O. A.; Suter, D.; Karczewski, G.; Wojtowicz, T.; Kossut, J.; Petrov, V. V.; Dolgikh, Yu. K.; Pawlis, A.; Bayer, M.

2014-08-01

297

NASA Astrophysics Data System (ADS)

In complex biological or colloidal samples, magnetic relaxation dispersion (MRD) experiments using the field-cycling technique can characterize molecular motions on time scales ranging from nanoseconds to microseconds, provided that a rigorous theory of nuclear spin relaxation is available. In gels, cross-linked proteins, and biological tissues, where an immobilized macromolecular component coexists with a mobile solvent phase, nuclear spins residing in solvent (or cosolvent) species relax predominantly via exchange-mediated orientational randomization (EMOR) of anisotropic nuclear (electric quadrupole or magnetic dipole) couplings. The physical or chemical exchange processes that dominate the MRD typically occur on a time scale of microseconds or longer, where the conventional perturbation theory of spin relaxation breaks down. There is thus a need for a more general relaxation theory. Such a theory, based on the stochastic Liouville equation (SLE) for the EMOR mechanism, is available for a single quadrupolar spin I = 1. Here, we present the corresponding theory for a dipole-coupled spin-1/2 pair. To our knowledge, this is the first treatment of dipolar MRD outside the motional-narrowing regime. Based on an analytical solution of the spatial part of the SLE, we show how the integral longitudinal relaxation rate can be computed efficiently. Both like and unlike spins, with selective or non-selective excitation, are treated. For the experimentally important dilute regime, where only a small fraction of the spin pairs are immobilized, we obtain simple analytical expressions for the auto-relaxation and cross-relaxation rates which generalize the well-known Solomon equations. These generalized results will be useful in biophysical studies, e.g., of intermittent protein dynamics. In addition, they represent a first step towards a rigorous theory of water 1H relaxation in biological tissues, which is a prerequisite for unravelling the molecular basis of soft-tissue contrast in clinical magnetic resonance imaging.

Chang, Zhiwei; Halle, Bertil

2013-10-01

298

Natural reference for nuclear high-spin states

We suggest two new representations of the data on rotational nuclei. The first is reference-free and the second arises from a natural reference related to the variable moment of inertia model parameters of the ground-state band of the system. As such, neither representation contains any free parameters. By defining a 'configuration spin' we show how a new ground-state band reference can be applied. Its use allows a complete description of the changes associated with the first, and higher, band crossings. We apply these new representations to discuss the nature of the first band crossing along even-even isotopic chains in the erbium and osmium isotopes and to odd-even nuclei in the vicinity of {sup 158}Er.

Rowley, Neil; Ollier, James; Simpson, John [UMR 8608, Universite de Paris Sud/IN2P3, Division de Physique Theorique, Institut de Physique Nucleaire, F-91406 Orsay Cedex (France); STFC Daresbury Laboratory, Daresbury, Warrington WA44AD (United Kingdom)

2009-08-15

299

Microscopic control of $^{29}$Si nuclear spins near phosphorus donors in silicon

Dynamic nuclear polarization of $^{29}$Si nuclei in resolved lattice sites near the phosphorus donors in natural silicon of has been created using the Overhauser and solid effects. Polarization has been observed as a pattern of well separated holes and peaks in the electron spin resonance line of the donor. The Overhauser effect in ESR hole burning experiments was used to manipulate the polarization of $^{29}$Si spins at ultra low (100-500 mK) temperatures and in high magnetic field of 4.6 T. Extremely narrow holes of 15 mG width were created after several seconds of pumping.

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

2014-01-01

300

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

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

301

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

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

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

2013-09-07

302

Nanoscale magnetic field mapping with a single spin scanning probe magnetometer

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

303

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

304

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

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

305

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

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

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

1999-01-01

306

Nanoscale magnetic field mapping with a single spin scanning probe magnetometer

NASA Astrophysics Data System (ADS)

We demonstrate quantitative magnetic field mapping with nanoscale resolution, by applying a lock-in technique on the electron spin resonance frequency of a single nitrogen-vacancy defect placed at the apex of an atomic force microscope tip. In addition, we report an all-optical magnetic imaging technique which is sensitive to large off-axis magnetic fields, thus extending the operation range of diamond-based magnetometry. Both techniques are illustrated by using a magnetic hard disk as a test sample. Owing to the non-perturbing and quantitative nature of the magnetic probe, this work should open up numerous perspectives in nanomagnetism and spintronics.

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

2012-04-01

307

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

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

Zhong-Bo Kang; Jian-Wei Qiu

2008-11-19

308

Multiferroicity in spin ice Ho2Ti2O7: An investigation on single crystals

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

309

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

NASA Astrophysics Data System (ADS)

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

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

2000-06-01

310

Isovector spin observables in nuclear charge reactions at LAMPF

LAMPF has undertaken a major development program to upgrade facilities for nuclear charge-exchange studies at intermediate energies. The major components of this upgrade are a medium-resolution spectrometer and neutron time-of-flight system for good resolution (delta E < 1 MeV) charge-exchange perograms in (n,p) and (p,n) respectively. Major emphasis is placed on polarization phenomena using polarized beams and analyzing the polarization of the outgoing particle.

McClelland, J.B.

1988-01-01

311

NASA Astrophysics Data System (ADS)

Nuclear inelastic scattering (NIS) spectra of [Fe(ptz) 6](BF 4) 2 (ptz = 1- n-propyl-tetrazole) have been measured for five phases differing in spin state and crystallographic structure. Different spectral patterns have been found for the low-spin and high-spin phases and are described in terms of normal coordinate analysis of the complex molecule. For both low-spin and high-spin phases the conversion from ordered to disordered phase results in splitting of the observed NIS bands. Packing becomes visible in the NIS spectra via coupling of the Fe-N stretching vibrations with those of the terminal n-propyl groups. The DFT-based normal coordinate analysis also reveals the character of Raman markers.

Böttger, Lars H.; Chumakov, Aleksandr I.; Matthias Grunert, C.; Gütlich, Philipp; Kusz, Joachim; Paulsen, Hauke; Ponkratz, Ulrich; Rusanov, Ventzislav; Trautwein, Alfred X.; Wolny, Juliusz A.

2006-09-01

312

Spin-Dependent Structure Functions in Nuclear Matter and the Polarized EMC Effect

An excellent description of both spin-independent and spin-dependent quark distributions and structure functions has been obtained with a modified Nambu-Jona-Lasinio model, which is free of unphysical thresholds for nucleon decay into quarks--hence incorporating an important aspect of confinement. We utilize this model to investigate nuclear medium modifications to structure functions and find that we are readily able to reproduce both nuclear matter saturation and the experimental F{sub 2N}{sup A}/F{sub 2N} ratio, that is, the European Muon Collaboration (EMC) effect. Applying this framework to determine g{sub 1p}{sup A}, we find that the ratio g{sub 1p}{sup A}/g{sub 1p} differs significantly from unity, with the quenching caused by the nuclear medium being about twice that of the spin-independent case. This represents an exciting result, which, if confirmed experimentally, will reveal much about the quark structure of nuclear matter.

Cloeet, I.C. [Special Research Centre for the Subatomic Structure of Matter and Department of Physics and Mathematical Physics, University of Adelaide, South Australia 5005 (Australia); Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States); Bentz, W. [Department of Physics, School of Science, Tokai University, Hiratsuka-shi, Kanagawa 259-1292 (Japan); Thomas, A.W. [Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States)

2005-07-29

313

Spin-dependent structure functions in nuclear matter and the polarized EMC effect

An excellent description of both spin-independent and spin-dependent quark distributions and structure functions has been obtained with a modified Nambu-Jona-Lasinio model, which is free of unphysical thresholds for nucleon decay into quarks--hence incorporating an important aspect of confinement. We utilize this model to investigate nuclear medium modifications to structure functions, and find that we are readily able to reproduce both nuclear matter saturation and the experimental F{sub 2N}{sup A}/F{sub 2N} ratio, that is, the EMC effect. Applying this framework to determine g{sub 1p}{sup A}, we find that the ratio g{sub 1p}{sup A}/g{sub 1p} differs significantly from 1, with the quenching caused by the nuclear medium being about twice that of the spin-independent case. This represents an exciting result, which if confirmed experimentally, will reveal much about the quark structure of nuclear matter.

I.C. Cloet; W. Bentz; A.W. Thomas

2005-04-01

314

High-pressure magic angle spinning nuclear magnetic resonance.

A high-pressure magic angle spinning (MAS) NMR capability, consisting of a reusable high-pressure MAS rotor, a high-pressure rotor loading/reaction chamber for in situ sealing and re-opening of the high-pressure MAS rotor, and a MAS probe with a localized RF coil for background signal suppression, is reported. The unusual technical challenges associated with development of a reusable high-pressure MAS rotor are addressed in part by modifying standard ceramics for the rotor sleeve by abrading the internal surface at both ends of the cylinder. In this way, not only is the advantage of ceramic cylinders for withstanding very high-pressure utilized, but also plastic bushings can be glued tightly in place so that other removable plastic sealing mechanisms/components and O-rings can be mounted to create the desired high-pressure seal. Using this strategy, sealed internal pressures exceeding 150 bars have been achieved and sustained under ambient external pressure with minimal loss of pressure for 72 h. As an application example, in situ(13)C MAS NMR studies of mineral carbonation reaction intermediates and final products of forsterite (Mg(2)SiO(4)) reacted with supercritical CO(2) and H(2)O at 150 bar and 50°C are reported, with relevance to geological sequestration of carbon dioxide. PMID:21862372

Hoyt, David W; Turcu, Romulus V F; Sears, Jesse A; Rosso, Kevin M; Burton, Sarah D; Felmy, Andrew R; Hu, Jian Zhi

2011-10-01

315

High-pressure magic angle spinning nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

A high-pressure magic angle spinning (MAS) NMR capability, consisting of a reusable high-pressure MAS rotor, a high-pressure rotor loading/reaction chamber for in situ sealing and re-opening of the high-pressure MAS rotor, and a MAS probe with a localized RF coil for background signal suppression, is reported. The unusual technical challenges associated with development of a reusable high-pressure MAS rotor are addressed in part by modifying standard ceramics for the rotor sleeve by abrading the internal surface at both ends of the cylinder. In this way, not only is the advantage of ceramic cylinders for withstanding very high-pressure utilized, but also plastic bushings can be glued tightly in place so that other removable plastic sealing mechanisms/components and O-rings can be mounted to create the desired high-pressure seal. Using this strategy, sealed internal pressures exceeding 150 bars have been achieved and sustained under ambient external pressure with minimal loss of pressure for 72 h. As an application example, in situ13C MAS NMR studies of mineral carbonation reaction intermediates and final products of forsterite (Mg 2SiO 4) reacted with supercritical CO 2 and H 2O at 150 bar and 50 °C are reported, with relevance to geological sequestration of carbon dioxide.

Hoyt, David W.; Turcu, Romulus V. F.; Sears, Jesse A.; Rosso, Kevin M.; Burton, Sarah D.; Felmy, Andrew R.; Hu, Jian Zhi

2011-10-01

316

Role of spin state on the geometry and nuclear quadrupole resonance parameters in hemin complex.

Theoretical calculations of structural parameters, 57Fe, 14N and 17 O electric field gradient (EFG) tensors for full size-hemin group have been carried out using density functional theory. These calculations are intended to shed light on the difference between the geometry parameters, nuclear quadrupole coupling constants (QCC), and asymmetry parameters (eta Q) found in three spin states of hemin; doublet, quartet and sextet. The optimization results reveal a significant change for propionic groups and porphyrin plane in different spin states. It is found that all principal components of EFG tensor at the iron site are sensitive to electronic and geometry structures. A relationship between the EFG tensor at the 14N and 17 O sites and the spin state of hemin complex is also detected. PMID:18353527

Behzadi, Hadi; van der Spoel, David; Esrafili, Mehdi D; Parsafar, Gholam Abbas; Hadipour, Nasser L

2008-05-01

317

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

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

2010-02-17

318

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

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

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

2014-01-01

319

Temperature induced Spin Switching in SmFeO3 Single Crystal

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

320

Temperature induced spin switching in SmFeO3 single crystal.

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

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

2014-01-01

321

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

322

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

323

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

324

Nuclear Spin-Lattice Relaxation Time Due to the Orbital Interaction

In the free electron model the spin-lattice relaxation time {T1}(orb) due to the interaction with the orbital motion of conduction electrons diverges if the nuclear Zeeman energy is neglected. Without neglecting it, {T1}(orb) with the field dependence of a form log(Hext) is derived for high magnetic fields. The divergence which arises for Hext{=}0 is removed by taking into account the

Eijiro Haga; Syozo Maeda

1972-01-01

325

NUCLEAR RELAXATION AND SPIN DYNAMICS IN NMP TCNQ F. DEVREUX (*), M. GUGLIELMI and M. NECHTSCHEIN (*)

541 NUCLEAR RELAXATION AND SPIN DYNAMICS IN NMP TCNQ F. DEVREUX (*), M. GUGLIELMI and M Ã©tÃ© effectuÃ©es en fonction de la frÃ©quence dans des echantillons de NMP TCNQ sÃ©lectivement deutÃ©riÃ©s Ã©lectroniques localisÃ©s sur les chaines de NMP et associÃ©s Ã un transfert de charge incomplet. AprÃ¨s

Paris-Sud XI, UniversitÃ© de

326

Theory of magnetic quantum oscillations in the nuclear spin-lattice relaxation rate-T-11, in quasi-two-dimensional conductors at low temperatures and under strong magnetic fields, is presented. We show a close similarity between the magnetic field dependence of T-11 and that of rhoxx in the quantum Hall effect. The shape and the amplitude of the oscillations in T-11 depend strongly on band anisotropy,

I. D. Vagner; Tsofar Maniv

1988-01-01

327

Nuclear-spin relaxation of ²º?Pb in ferroelectric powders

The ²º?Pb nuclear system (nuclear spin I = 1/2; magnetic Moment ? ?0.58 ?N; isotopic abundance ? 22%) in ferroelectric solids has been proposed for a search for a Schiff moment associated with simultaneous violation of parity (P) and time-reversal invariance (T) in fundamental interactions [1] (see also a discussion of the sensitivity of such search in Ref. [2]). The idea is that, due to the Schiff moment, a ferroelectric sample would acquire a P,T-odd magnetic polarization along the direction of its electric polarization. In conclusion, we have presented the first experimental study of relaxation properties of ²º?Pb in PT and PZT below room temperature. We find that above T? 50 K, longitudinal relaxation rate follows the T² dependence characteristic of the two-phonon Raman process. On the other hand, as the temperature is decreased below T? 50 K, the longitudinal relaxation rates drop slower than ?T2 (as opposed to ?T7 expected for the Raman process), and the relaxation is probably due to a direct process associated with paramagnetic impurities and nuclear-spin diffusion. While the longitudinal relaxation times T? vary between several seconds and over an hour in the temperature range between 290 and 10 K, the transverse relaxation time T? is found to be ?1.5 ms for all temperatures and all powder samples studied. D: we never discuss the origin of T? relaxation. Maybe we should. 1.5 ms is only a bit shorter from what would be expected from nuclear spin-spin interactions. Any comments? At some point Sasha asked Oleg to calculate T? exactly for PT and PZT, but I forgot what was the result. If such calculation exists, it would be great to compare with the expt. result. The obtained results provide an important input in the design of the experiments to search for P,T-violating effects in solid ferroelectrics

Bouchard, Louis S.; Sushkov, Alexander O.; Budker, Dmitry; Ford, Joe; Lipton, Andrew S.

2008-02-05

328

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

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

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

1990-01-01

329

NASA Astrophysics Data System (ADS)

Optical detection of single atoms captured in solid noble gas matrices provides an alternative technique to study rare nuclear reactions relevant to nuclear astrophysics. I will describe the prospects of applying this approach for cross section measurements of the ^22Ne,,),25Mg reaction, which is the crucial neutron source for the weak s process inside of massive stars. Noble gas solids are a promising medium for the capture, detection, and manipulation of atoms and nuclear spins. They provide stable and chemically inert confinement for a wide variety of guest species. Because noble gas solids are transparent at optical wavelengths, the guest atoms can be probed using lasers. We have observed that ytterbium in solid neon exhibits intersystem crossing (ISC) which results in a strong green fluorescence (546 nm) under excitation with blue light (389 nm). Several groups have observed ISC in many other guest-host pairs, notably magnesium in krypton. Because of the large wavelength separation of the excitation light and fluorescence light, optical detection of individual embedded guest atoms is feasible. This work is supported by DOE, Office of Nuclear Physics, under contract DE-AC02-06CH11357.

Singh, Jaideep; Bailey, Kevin G.; Lu, Zheng-Tian; Mueller, Peter; O'Connor, Thomas P.; Xu, Chen-Yu; Tang, Xiaodong

2013-04-01

330

Violation of entropic Leggett-Garg inequality in nuclear spins

NASA Astrophysics Data System (ADS)

We report an experimental study of recently formulated entropic Leggett-Garg inequality (ELGI) by Usha Devi [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.87.052103 87, 052103 (2013)]. This inequality places a bound on the statistical measurement outcomes of dynamical observables describing a macrorealistic system. Such a bound is not necessarily obeyed by quantum systems, and therefore provides an important way to distinguish quantumness from classical behavior. Here we study ELGI using a two-qubit nuclear magnetic resonance system. To perform the noninvasive measurements required for the ELGI study, we prepare the system qubit in a maximally mixed state as well as use the “ideal negative result measurement” procedure with the help of an ancilla qubit. The experimental results show a clear violation of ELGI by over four standard deviations. These results agree with the predictions of quantum theory. The violation of ELGI is attributed to the fact that certain joint probabilities are not legitimate in the quantum scenario, in the sense they do not reproduce all the marginal probabilities. Using a three-qubit system, we also demonstrate that three-time joint probabilities do not reproduce certain two-time marginal probabilities.

Katiyar, Hemant; Shukla, Abhishek; Rao, K. Rama Koteswara; Mahesh, T. S.

2013-05-01

331

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

NASA Astrophysics Data System (ADS)

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

Hummel, Paul Jeremy

332

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

333

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

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

334

Rotor Design for High Pressure Magic Angle Spinning Nuclear Magnetic Resonance

High pressure magic angle spinning (MAS) nuclear magnetic resonance (NMR) with a sample spinning rate exceeding 2.1 kHz and pressure greater than 165 bar has never been realized. In this work, a new sample cell design is reported, suitable for constructing cells of different sizes. Using a 7.5 mm high pressure MAS rotor as an example, internal pressure as high as 200 bar at a sample spinning rate of 6 kHz is achieved. The new high pressure MAS rotor is re-usable and compatible with most commercial NMR set-ups, exhibiting low 1H and 13C NMR background and offering maximal NMR sensitivity. As an example of its many possible applications, this new capability is applied to determine reaction products associated with the carbonation reaction of a natural mineral, antigorite ((Mg,Fe2+)3Si2O5(OH)4), in contact with liquid water in water-saturated supercritical CO2 (scCO2) at 150 bar and 50 deg C. This mineral is relevant to the deep geologic disposal of CO2, but its iron content results in too many sample spinning sidebands at low spinning rate. Hence, this chemical system is a good case study to demonstrate the utility of the higher sample spinning rates that can be achieved by our new rotor design. We expect this new capability will be useful for exploring solid-state, including interfacial, chemistry at new levels of high-pressure in a wide variety of fields.

Turcu, Romulus V.F.; Hoyt, David W.; Rosso, Kevin M.; Sears, Jesse A.; Loring, John S.; Felmy, Andrew R.; Hu, Jian Z.

2013-01-01

335

Analytic treatment of nuclear spin-lattice relaxation for diffusion in a cone model

We consider nuclear spin-lattice relaxation rate resulted from a diffusion equation for rotational wobbling in a cone. We show that the widespread point of view that there are no analytical expressions for correlation functions for wobbling in a cone model is invalid and prove that nuclear spin-lattice relaxation in this model is exactly tractable and amenable to full analytical description. The mechanism of relaxation is assumed to be due to dipole-dipole interaction of nuclear spins and is treated within the framework of the standard Bloemberger, Purcell, Pound - Solomon scheme. We consider the general case of arbitrary orientation of the cone axis relative the magnetic field. The BPP-Solomon scheme is shown to remain valid for systems with the distribution of the cone axes depending only on the tilt relative the magnetic field but otherwise being isotropic. We consider the case of random isotropic orientation of cone axes relative the magnetic field taking place in powders. Also we consider the cases of their predominant orientation along or opposite the magnetic field and that of their predominant orientation transverse to the magnetic field which may be relevant for, e.g., liquid crystals. Besides we treat in details the model case of the cone axis directed along the magnetic field. The latter provides direct comparison of the limiting case of our formulas with the textbook formulas for free isotropic rotational diffusion. The dependence of the spin-lattice relaxation rate on the cone half-width yields results similar to those predicted by the model-free approach.

A. E. Sitnitsky

2011-08-02

336

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

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

337

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

Some estimates for the transverse Single Spin Asymmetry, A_N, in the inclusive processes l p(transv. pol.) --> h X, given in a previous paper, are expanded and compared with new experimental data. The predictions are based on the Sivers distributions and the Collins fragmentation functions which fit the azimuthal asymmetries measured in Semi-Inclusive Deep Inelastic Scattering (SIDIS) processes (l p(transv. pol.) --> l' h X). The factorisation in terms of Transverse Momentum Dependent distribution and fragmentation functions (TMD factorisation) -- i.e., the theoretical framework in which SIDIS azimuthal asymmetries are analysed -- is assumed to hold also for the inclusive process l p --> h X at large P_T. The values of A_N thus obtained agree in sign and shape with the data. Some predictions are given for future experiments.

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

2014-04-25

338

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

NASA Astrophysics Data System (ADS)

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

Booker, Richard Delane

339

NASA Technical Reports Server (NTRS)

The survey of negative pion absorption reactions on light and medium nuclei was continued. Muon spin precession was studied using an iron target. An impulse approximation model of the pion absorption process implied that the ion will absorb almost exclusively on nucleon pairs, single nucleon absorption being suppressed by energy and momentum conservation requirements. For measurements on both paramagnetic and ferromagnetic iron, the external magnetic field was supplied by a large C-type electromagnet carrying a current of about 100 amperes.

1974-01-01

340

NASA Astrophysics Data System (ADS)

The single and double spin asymmetries At and Aet have been measured in pi- electro-production off the deuteron using a longitudinally polarized electron beam and a polarized ND3 target. The electron beam was polarized using a strained GaAs cathode and the target was polarized using Dynamic Nuclear Polarization. The data were collected at beam energies of 1.6, 1.7, 2.5 and 4.2 GeV in Hall B at Jefferson Lab in the spring of 2001. The final state particles were detected in the CEBAF Large Acceptance Spectrometer (CLAS). The d(e,e'pi-p)p exclusive channel was identified using the missing mass technique and the asymmetries were extracted as a function of the momentum transfer Q2, invariant mass W, and center of mass pion angles cos(theta*) and ?*. The results are generally in agreement with the phenomenological model MAID at low energies, but there are discrepancies in the 2nd and 3rd resonance regions, as well as at forward angles.

Careccia, Sharon L.

341

NASA Astrophysics Data System (ADS)

The GaAs, GaAs:In,Cr, and GaAs:Mn single crystals were grown by the vertical gradient freeze (VGF) technique. The spin-lattice relaxation processes of 69Ga, 71Ga and 75As have been studied for the undoped GaAs single crystals and crystals doped with paramagnetic impurities Cr and Mn. The relaxation processes in all samples are well described by a single exponential function. The T2 dependence of the relaxation rate was in accordance with that predicted for the Raman mechanism of nuclear spin-lattice relaxation for all crystals investigated. The manganese doping showed a tendency to shorten slightly the spin-lattice relaxation times.

Yeom, T. H.; Kim, I. G.; Choh, S. H.; Hong, K. S.; Park, Y. J.; Min, S.-K.

1999-06-01

342

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

343

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

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

Manassen, Yishay

344

Ignition conditions for inertial confinement fusion targets with a nuclear spin-polarized DT fuel

NASA Astrophysics Data System (ADS)

The nuclear fusion cross-section is modified when the spins of the interacting nuclei are polarized. In the case of deuterium-tritium it has been theoretically predicted that the nuclear fusion cross-section could be increased by a factor ? = 1.5 if all the nuclei were polarized. In inertial confinement fusion this would result in a modification of the required ignition conditions. Using numerical simulations it is found that the required hot-spot temperature and areal density can both be reduced by about 15% for a fully polarized nuclear fuel. Moreover, numerical simulations of a directly driven capsule show that the required laser power and energy to achieve a high gain scale as ?-0.6 and ?-0.4 respectively, while the maximum achievable energy gain scales as ?0.9.

Temporal, M.; Brandon, V.; Canaud, B.; Didelez, J. P.; Fedosejevs, R.; Ramis, R.

2012-10-01

345

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

Randeria, Mallika

2012-01-01

346

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

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

Clarice D. Aiello; Paola Cappellaro

2014-10-21

347

Nuclear magnetic resonance study of spin relaxation and magnetic field gradients in maple leaves.

1H Nuclear magnetic resonance techniques were used to measure the distributions of spin-spin relaxation times, T2, and of magnetic field gradients in both the chloroplast and nonchloroplast water compartments of maple leaves (Acer platanoides). Results showed that encounters between water molecules and membranes inside chloroplasts provide an inefficient relaxation mechanism; i.e., chloroplast membranes interact weakly with water molecules. Gradient measurements indirectly measured the sizes of chloroplasts by showing that water in the chloroplasts is confined to small compartments a few microns in diameter. A comparison between measured gradients and gradients calculated for a model leaf indicated that chloroplasts are somewhat more likely to occupy positions along cell walls adjacent to air spaces, but also they may be found in the interiors of cells. PMID:8519965

McCain, D C

1995-09-01

348

Nuclear Spin relaxation mediated by Fermi-edge electrons in n-type GaAs

NASA Astrophysics Data System (ADS)

A method based on the optical orientation technique was developed to measure the nuclear-spin lattice relaxation time T 1 in semiconductors. It was applied to bulk n-type GaAs, where T 1 was measured after switching off the optical excitation in magnetic fields from 400 to 1200 G at low (< 30 K) temperatures. The spin-lattice relaxation of nuclei in the studied sample with n D = 9 × 1016 cm-3 was found to be determined by hyperfine scattering of itinerant electrons (Korringa mechanism) which predicts invariability of T 1 with the change in magnetic field and linear dependence of the relaxation rate on temperature. This result extends the experimentally verified applicability of the Korringa relaxation law in degenerate semiconductors, previously studied in strong magnetic fields (several Tesla), to the moderate field range.

Kotur, M.; Dzhioev, R. I.; Kavokin, K. V.; Korenev, V. L.; Namozov, B. R.; Pak, P. E.; Kusrayev, Yu. G.

2014-03-01

349

Nuclear spin-lattice relaxation from fractional wobbling in a cone

We consider nuclear spin-lattice relaxation rate resulted from a fractional diffusion equation for anomalous rotational wobbling in a cone. The mechanism of relaxation is assumed to be due to dipole-dipole interaction of nuclear spins and is treated within the framework of the standard Bloemberger, Purcell, Pound - Solomon scheme. We consider the general case of arbitrary orientation of the cone axis relative the magnetic field. The BPP-Solomon scheme is shown to remain valid for systems with the distribution of the cone axes depending only on the tilt relative the magnetic field but otherwise being isotropic. We consider the case of random isotropic orientation of cone axes relative the magnetic field taking place in powders. Also we consider the case of their predominant orientation along or opposite the magnetic field and that of their predominant orientation transverse to the magnetic field which may be relevant for, e.g., liquid crystals. Besides we treat in details the model case of the cone axis directed along the magnetic field. The latter provides direct comparison of the limiting case of our formulas with the textbook formulas for ordinary isotropic rotational diffusion. We show that the present model enables one to obtain naturally the well known power law for Larmor frequency dependence of the spin-lattice relaxation rate. The latter is observed in some complex systems. From this law the dependence of the fractional diffusion coefficient on the fractional index is obtained to have a rather simple functional form. The dependence of the spin-lattice relaxation rate on the cone half-width for the case of ordinary rotational diffusion yields results similar to those predicted by the model-free approach.

A. E. Sitnitsky

2011-01-13

350

The lowest order constrained variational technique has been used to investigate some of the thermodynamic properties of spin-polarized hot asymmetric nuclear matter, such as the free energy, symmetry energy, susceptibility, and equation of state. We have shown that the symmetry energy of the nuclear matter is substantially sensitive to the value of spin polarization. Our calculations show that the equation of state of the polarized hot asymmetric nuclear matter is stiffer for higher values of the polarization as well as the isospin asymmetry parameter. Our results for the free energy and susceptibility show that spontaneous ferromagnetic phase transition cannot occur for hot asymmetric matter.

Bigdeli, M. [Department of Physics, Zanjan University, Post Office Box 45195-313, Zanjan (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha, Post Office Box 55134-441, Maragha (Iran, Islamic Republic of); Bordbar, G. H. [Department of Physics, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha, Post Office Box 55134-441, Maragha (Iran, Islamic Republic of); Poostforush, A. [Department of Physics, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of)

2010-09-15

351

NASA Astrophysics Data System (ADS)

The enhancement of the spin-lattice relaxation rate for nuclear spins in a ligand bound to a paramagnetic metal ion [known as the paramagnetic relaxation enhancement (PRE)] arises primarily through the dipole-dipole (DD) interaction between the nuclear spins and the electron spins. In solution, the DD interaction is modulated mostly by reorientation of the nuclear spin-electron spin axis and by electron spin relaxation. Calculations of the PRE are in general complicated, mainly because the electron spin interacts so strongly with the other degrees of freedom that its relaxation cannot be described by second-order perturbation theory or the Redfield theory. Three approaches to resolve this problem exist in the literature: The so-called slow-motion theory, originating from Swedish groups [Benetis et al., Mol. Phys. 48, 329 (1983); Kowalewski et al., Adv. Inorg. Chem. 57, (2005); Larsson et al., J. Chem. Phys. 101, 1116 (1994); T. Nilsson et al., J. Magn. Reson. 154, 269 (2002)] and two different methods based on simulations of the dynamics of electron spin in time domain, developed in Grenoble [Fries and Belorizky, J. Chem. Phys. 126, 204503 (2007); Rast et al., ibid. 115, 7554 (2001)] and Ann Arbor [Abernathy and Sharp, J. Chem. Phys. 106, 9032 (1997); Schaefle and Sharp, ibid. 121, 5387 (2004); Schaefle and Sharp, J. Magn. Reson. 176, 160 (2005)], respectively. In this paper, we report a numerical comparison of the three methods for a large variety of parameter sets, meant to correspond to large and small complexes of gadolinium(III) and of nickel(II). It is found that the agreement between the Swedish and the Grenoble approaches is very good for practically all parameter sets, while the predictions of the Ann Arbor model are similar in a number of the calculations but deviate significantly in others, reflecting in part differences in the treatment of electron spin relaxation. The origins of the discrepancies are discussed briefly.

Belorizky, Elie; Fries, Pascal H.; Helm, Lothar; Kowalewski, Jozef; Kruk, Danuta; Sharp, Robert R.; Westlund, Per-Olof

2008-02-01

352

NASA Astrophysics Data System (ADS)

We show that the coherence properties of the nuclear spin states of rare-earth ions in solids can be manipulated by small applied electric fields. This was done by measuring the Stark effect on the nuclear quadrupole transitions of Eu151 in Y2SiO5 (YSO) using a combination of Raman heterodyne optical detection and Stark modulated quadrupole echoes to achieve high sensitivity. The measured Stark coefficients were 0.42 and 1.0 Hz cm /V for the two quadrupole transitions at 34.54 and 46.20 MHz, respectively. The long decoherence time of the nuclear spin states (25 ms) allowed us to make the measurements in very low electric fields of ˜10 V/cm, which produced 100% modulation of the nuclear spin echo, and to measure Stark shifts of ˜1 Hz or 20 ppm of the inhomogeneous linewidth.

Macfarlane, R. M.; Arcangeli, A.; Ferrier, A.; Goldner, Ph.

2014-10-01

353

NASA Astrophysics Data System (ADS)

In order to carry out orientation dependent nuclear resonance scattering (NRS) experiments on small single crystals of e.g. iron proteins and/or chemical complexes but also on surfaces and other micrometer-sized samples a 2-circle goniometer including sample positioning optics has been installed at beamline P01, PETRA III, DESY, Hamburg. This sample environment is now available for all users of this beamline. Sample cooling is performed with a cryogenic gas stream which allows NRS measurements in the temperature range from 80 up to 400 K. In a first test this new sample environment has been used in order to investigate the orientation dependence of the nuclear inelastic scattering (NIS) signature of (i) a dinuclear iron(II) spin crossover (SCO) system and (ii) a hydrogen peroxide treated metmyoglobin single crystal.

Rackwitz, Sergej; Faus, Isabelle; Schmitz, Markus; Kelm, Harald; Krüger, Hans-Jörg; Andersson, K. Kristoffer; Hersleth, Hans-Petter; Achterhold, Klaus; Schlage, Kai; Wille, Hans-Christian; Schünemann, Volker; Wolny, Juliusz A.

2014-04-01

354

NASA Astrophysics Data System (ADS)

Experimental evidence of observing a rather unusual spin-locking spin echo (SLSE) effect in the fields of two multi-pulse sequences ( ?0) x - ( ? - ?x - 2 ? - ?x - 2 ? - ?- x - 2 ? - ?- x - ?) n and ( ?0) x - ( ? - ?x - 2 ? - ?y - ?) n in 14N nuclear quadrupole resonance is presented. It was demonstrated that the SLSE effect is observed only in the even pulse intervals of both sequences. All experiments were carried out at room temperature on a powder sample of NaNO 2. A theoretical description of the effect is given.

Mikhaltsevitch, V. T.

2005-12-01

355

We introduce spin projection methods in the shell model Monte Carlo approach and apply them to calculate the spin distribution of level densities for iron-region nuclei using the complete (pf+g{sub 9/2}) shell. We compare the calculated distributions with the spin-cutoff model and extract an energy-dependent moment of inertia. For even-even nuclei and at low excitation energies, we observe a significant suppression of the moment of inertia and odd-even staggering in the spin dependence of level densities.

Alhassid, Y.; Liu, S. [Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06520 (United States); Nakada, H. [Department of Physics, Chiba University, Inage, Chiba 263-8522 (Japan)

2007-10-19

356

Electron-mediated nuclear-spin interactions between distant nitrogen-vacancy centers.

We propose a scheme enabling controlled quantum coherent interactions between separated nitrogen-vacancy centers in diamond in the presence of strong magnetic fluctuations. The proposed scheme couples nuclear qubits employing the magnetic dipole-dipole interaction between the electron spins and, crucially, benefits from the suppression of the effect of environmental magnetic field fluctuations thanks to a strong microwave driving. This scheme provides a basic building block for a full-scale quantum-information processor or quantum simulator based on solid-state technology. PMID:22107276

Bermudez, A; Jelezko, F; Plenio, M B; Retzker, A

2011-10-01

357

Despite the concept of nuclear spin isomers (NSIs) exists since the early days of quantum mechanics, only few approaches have been suggested to separate different NSIs. Here, a method is proposed to discriminate different NSIs of a quinodimethane derivative using its electronic excited state dynamics. After electronic excitation by a laser field with femtosecond time duration, a difference in the behavior of several quantum mechanical operators can be observed. A pump-probe experimental approach for separating these different NSIs is then proposed. PMID:25362315

Obaid, Rana; Kinzel, Daniel; Oppel, Markus; González, Leticia

2014-10-28

358

Interlayer transport of nuclear spin polarization in ? = 2/3 quantum Hall states

We investigated the interlayer diffusion of nuclear spin polarization (NSP) by using the phase transition point of quantum Hall states at a Landau level filling factor of ? ? 2/3 in a double quantum well sample. When the NSP is current-pumped in one layer, the magnetoresistance in the other layer is enhanced after a delay of 150 s and the raising speed of this layer is lower than that of the pumped layer. The delay and lower value of the raising speed are explained by the diffusion of NSP.

Tsuda, S.; Nguyen, M. H. [Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Terasawa, D.; Fukuda, A. [Department of Physics, Hyogo College of Medicine, Nishinomiya, Hyogo 663-8501 (Japan); Zheng, Y. D.; Arai, T.; Sawada, A. [Research Center for Low Temperatures and Materials Sciences, Kyoto University, Kyoto 606-8501 (Japan)

2013-12-04

359

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

NASA Astrophysics Data System (ADS)

The cause for the preferred spin orientation in magnetic systems containing spin-1/2 transition-metal ions was explored by studying the origin of the easy-plane anisotropy of the spin-1/2 Cu2+ ions in CuCl2.2H2O, LiCuVO4, CuCl2, and CuBr2 on the basis of density functional theory and magnetic dipole-dipole energy calculations as well as a perturbation theory treatment of the spin-orbit coupling. We find that the spin orientation observed for these spin-1/2 ions is not caused by their anisotropic spin exchange interactions, nor by their magnetic dipole-dipole interactions, but by the spin-orbit coupling associated with their crystal-field split d-states. Our study also predicts in-plane anisotropy for the Cu2+ ions of Bi2CuO4 and Li2CuO2. The results of our investigations dispel the mistaken belief that magnetic systems with spin-1/2 ions have no magnetic anisotropy induced by spin-orbit coupling.

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

2014-09-01

360

Spin state of Mn3O4 investigated by 55Mn nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

The 55Mn nuclear magnetic resonance spectrum for the spinel oxide Mn3O4 was measured at low temperature to investigate the spin structure in the ground state. The spectrum consists of three peaks in the frequency range of 250-265 MHz, which corresponds to the hyperfine field range of 24-25 T. The temperature dependence of the spectrum and the rf enhancement factor show that Mn3+ ions have two different magnetic moments, one of which is strongly related to the commensurate-incommensurate phase transition. This is consistent with the picture of two magnetic moments R and S claimed from the results of a neutron experiment. Comparison with a heat-treated sample suggests a relation between the two different magnetic moments and the occupation sites of manganese ions, the tetrahedral and octahedral sites. Theoretical estimations of the dipolar hyperfine field and the observed peak splitting predict that the magnetic moments of R and S differ by 5% at maximum. The spin-spin relaxation time has a frequency dependence that induces spectrum broadening and further splitting of the peak coming from S, indicating that the Suhl-Nakamura interaction is the major relaxation mechanism in Mn3O4.

Jo, Euna; An, Kyongmo; Shim, Jeong Hyun; Kim, Changsoo; Lee, Soonchil

2011-11-01

361

Limits on New Long Range Nuclear Spin-Dependent Forces Set with a K-{sup 3}He Comagnetometer

A magnetometer using spin-polarized K and {sup 3}He atoms occupying the same volume is used to search for anomalous nuclear spin-dependent forces generated by a separate {sup 3}He spin source. We measure changes in the {sup 3}He spin precession frequency with a resolution of 18 pHz and constrain anomalous spin forces between neutrons to be less than 2x10{sup -8} of their magnetic or less than 2x10{sup -3} of their gravitational interactions on a length scale of 50 cm. We present new limits on neutron coupling to light pseudoscalar and vector particles, including torsion, and constraints on recently proposed models involving unparticles and spontaneous breaking of Lorentz symmetry.

Vasilakis, G.; Brown, J. M.; Kornack, T. W.; Romalis, M. V. [Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States)

2009-12-31

362

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

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

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

2008-01-01

363

Controlling nuclear spin exchange via optical Feshbach resonances in ${}^{171}$Yb

Nuclear spin exchange occurs in ultracold collisions of fermionic alkaline-earth-like atoms due to a difference between s- and p-wave phase shifts. We study the use of an optical Feshbach resonance, excited on the ${}^1S_0 \\to {}^3P_1$ intercombination line of ${}^{171}$Yb, to affect a large modification of the s-wave scattering phase shift, and thereby optically mediate nuclear exchange forces. We perform a full multichannel calculation of the photoassociation resonances and wave functions and from these calculate the real and imaginary parts of the scattering length. As a figure of merit of this interaction, we estimate the fidelity to implement a $\\sqrt{SWAP}$ entangling quantum logic gate for two atoms trapped in the same well of an optical lattice. For moderate parameters one can achieve a gate fidelity of $\\sim95% $ in a time of $\\sim 50 \\mu$s.

Reichenbach, Iris; Deutsch, Ivan H

2009-01-01

364

Controlling nuclear spin exchange via optical Feshbach resonances in ${}^{171}$Yb

Nuclear spin exchange occurs in ultracold collisions of fermionic alkaline-earth-like atoms due to a difference between s- and p-wave phase shifts. We study the use of an optical Feshbach resonance, excited on the ${}^1S_0 \\to {}^3P_1$ intercombination line of ${}^{171}$Yb, to affect a large modification of the s-wave scattering phase shift, and thereby optically mediate nuclear exchange forces. We perform a full multichannel calculation of the photoassociation resonances and wave functions and from these calculate the real and imaginary parts of the scattering length. As a figure of merit of this interaction, we estimate the fidelity to implement a $\\sqrt{SWAP}$ entangling quantum logic gate for two atoms trapped in the same well of an optical lattice. For moderate parameters one can achieve a gate fidelity of $\\sim95% $ in a time of $\\sim 50 \\mu$s.

Iris Reichenbach; Paul S. Julienne; Ivan H. Deutsch

2009-05-28

365

High-performance algorithm to calculate spin- and parity-dependent nuclear level densities

A new algorithm for calculating the spin- and parity-dependent shell-model nuclear level densities using the moments method in the proton-neutron formalism is presented. A new, parallelized code based on this algorithm was developed and tested using up to 4000 cores for a set of nuclei from the sd-, pf-, and pf+g{sub 9/2}-model spaces. By comparing the nuclear level densities at low excitation energy for a given nucleus calculated in two model spaces, such as pf and pf+g{sub 9/2}, one can estimate the ground-state energy in the larger model space, which is not accessible to direct shell-model calculations due to the unmanageable dimension. Examples for the ground-state energies of for {sup 64}Ge and {sup 68}Se in the pf+g{sub 9/2} model space are presented.

Sen'kov, R. A.; Horoi, M. [Department of Physics, Central Michigan University, Mount Pleasant, Michigan 48859 (United States)

2010-08-15

366

A High-Performance Fortran Code to Calculate Spin- and Parity-Dependent Nuclear Level Densities

A high-performance Fortran code is developed to calculate the spin- and parity-dependent shell model nuclear level densities.The algorithm is based on the extension of methods of statistical spectroscopy and implies exact calculation of the first and second Hamiltonian moments for different configurations at fixed spin and parity. The proton-neutron formalism is used. We have applied the method for calculating the level densities for a set of nuclei in the sd-, pf-, and pf+g9/2 - model spaces. Examples of the calculations for 28Si (in the sd-model space) and 64Ge (in the pf+g9/2-model space) are presented. To illustrate the power of the method we estimate the ground state energy of 64Ge in the larger model space pf+g9/2, which is not accessible to direct shell model diagonalization due to the prohibitively large dimension, by comparing with the nuclear level densities at low excitation energy calculated in the smaller model space pf.

Sen'kov, R; Zelevinsky, V G

2012-01-01

367

A High-Performance Fortran Code to Calculate Spin- and Parity-Dependent Nuclear Level Densities

A high-performance Fortran code is developed to calculate the spin- and parity-dependent shell model nuclear level densities.The algorithm is based on the extension of methods of statistical spectroscopy and implies exact calculation of the first and second Hamiltonian moments for different configurations at fixed spin and parity. The proton-neutron formalism is used. We have applied the method for calculating the level densities for a set of nuclei in the sd-, pf-, and pf+g9/2 - model spaces. Examples of the calculations for 28Si (in the sd-model space) and 64Ge (in the pf+g9/2-model space) are presented. To illustrate the power of the method we estimate the ground state energy of 64Ge in the larger model space pf+g9/2, which is not accessible to direct shell model diagonalization due to the prohibitively large dimension, by comparing with the nuclear level densities at low excitation energy calculated in the smaller model space pf.

R. Sen'kov; M. Horoi; V. G. Zelevinsky

2012-06-20

368

Prediction of nuclear spin based on the behavior of ?-particle preformation probability

NASA Astrophysics Data System (ADS)

A realistic density-dependent nucleon-nucleon (NN) interaction with a finite-range exchange part which produces the nuclear matter saturation curve and the energy dependence of the nucleon-nucleus optical model potential is used to calculate the microscopic ?-nucleus potential in the well-established double-folding model. The main effect of antisymmetrization under exchange of nucleons between the ? and daughter nuclei has been included in the folding model through the finite-range exchange part of the NN interaction. The ?-decay half-lives have been determined using a microscopic potential within the semiclassical Wentzel-Kramers-Brillouin approximation in combination with the Bohr-Sommerfeld quantization condition. We systematically studied the preformation probability, S?, for ten even-even and odd mass heavy nuclei from Po to No isotopes. We found that S? has a regular behavior with N if the ? particle emitted from adjacent isotopes comes from the same energy levels or from a group of levels, assuming that the order of levels in this group is not changed. Sudden increase in S? is found when protons and neutrons holes exist below the Fermi levels. Based on the similarity in the behavior of S? with the neutron number for two adjacent nuclei, we try to determine the unknown or doubted nuclear spins and parities or at least correlate spins of adjacent nuclei.

Ismail, M.; Adel, A.

2013-11-01

369

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

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

Hideko Iwamoto

2012-04-01

370

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

371

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

NASA Astrophysics Data System (ADS)

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

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

2005-09-01

372

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

NASA Astrophysics Data System (ADS)

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

Koga, Mikito; Matsumoto, Masashige

2002-03-01

373

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

NASA Astrophysics Data System (ADS)

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

Ding, Baofu; Song, Qunliang; Alameh, Kamal

2014-05-01

374

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

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

375

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

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

2009-01-01

376

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

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

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

2000-01-01

377

Nuclear Spin of H_3^+ and H_2 in Dense Molecular Clouds

NASA Astrophysics Data System (ADS)

The ortho:para ratio of H_2 is a critical parameter for deuterium fractionation in cold, dense quiescent cores. The dominant reservoir for interstellar deuterium is in the inert molecule HD, but the exothermic reaction H_3^+ + HD ? H_2D^+ + H_2 + 220 K (and H_2D^+ + HD, etc.) can yield highly reactive species capable of distributing deuterium to other molecules. The barrier to the reverse reaction, however, can be overcome even at temperatures below 10 K when ortho-H_2 (o-H_2) reacts with H_2D^+ (or D_2H^+, D_3^+), as ortho-H_2 possesses ˜170 K of internal rotational energy in its ground state. Recent modeling work has demonstrated the importance of o-H_2 in cold, dense, highly depleted cores using a chemical network that includes all nuclear spin modifications of H_3^+, H_2, and their isotopologues, but the initial o-H_2 fraction is taken as a parameter in the model. Observationally or computationally constraining this quantity would aid in understanding deuterium fractionation in dense cores. To learn about the initial o-H_2 fraction in a cold core, we have modeled the chemistry of non-depleted dense interstellar clouds from which cold cores are thought to form. A simplified gas-phase chemical network consisting of 28 species and ˜170 reactions is combined with a physical model of a dense cloud, including time-dependent physical conditions. Included in the network are the nuclear spin modifications of H_2, H_2^+, and H_3^+, as well as nuclear spin dependent rate coefficients for the thermalization reactions H_2 + H^+ and H_3^+ + H_2. By modeling the time-dependent chemistry, we find that the ortho:para ratio of H_2 requires 10^7-10^8 years to reach steady state under ``standard'' dense cloud conditions, which is at least on the order of the cloud lifetime. The timescale depends on the ionization rate, the rate coefficients of the various H_3^+ + H_2 reactions, and the relative abundances of H_3^+ and H^+, but is largely insensitive to the total density and temperature. Even at steady state, the o-H_2 fraction is calculated to be >0.5% at 10 K, which is several orders of magnitude above its value at thermodynamic equilibrium. The prospects for using observations of the ortho:para ratio of H_3^+ as a probe of the H_2 ortho:para ratio will be discussed.

Crabtree, Kyle N.; McCall, Benjamin J.

2012-06-01

378

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

379

A cost-effective treatment of scalar-relativistic effects on nuclear magnetic shieldings based on the spin-free exact-two-component theory in its one-electron variant (SFX2C-1e) is presented. The SFX2C-1e scheme gains its computational efficiency, in comparison to the four-component approach, from a focus on spin-free contributions and from the elimination of the small component. For the calculation of nuclear magnetic shieldings, the separation of spin-free and spin-dependent terms in the parent four-component theory is carried out here for the matrix representation of the Dirac equation in terms of a restricted-magnetically balanced gauge-including atomic orbital basis. The resulting spin-free four-component matrix elements required to calculate nuclear magnetic shieldings are then used to construct the corresponding SFX2C-1e Hamiltonian and its perturbed counterpart in the context of SFX2C-1e analytic derivative theory. To demonstrate the applicability of the approach, we report coupled-cluster calculations for prototypical problems such as the (17)O shieldings of transition-metal oxo complexes (MO4(2-), M = Cr, Mo, and W) and the (129)Xe shieldings of xenon fluorides (XeF2, XeF4, and XeF6). PMID:23927241

Cheng, Lan; Gauss, Jürgen; Stanton, John F

2013-08-01

380

The neutrino-nucleon cross-section is calculated in dense nuclear matter at finite temperature, in view of applications to\\u000a supernovae and protoneutron stars. The main contribution to this parameter is provided by the axial response function. Nuclear\\u000a correlations play an important role: while the v-N crosssection is usually reduced by correlations, a collective mode in the spin S = 1 channel may

L. Mornasa; Avda Calvo Sotelo

381

. The neutrino-nucleon cross-section is calculated in dense nuclear matter at finite temperature, in view of applications to\\u000a supernovae and protoneutron stars. The main contribution to this parameter is provided by the axial response function. Nuclear\\u000a correlations play an important role: while the ?-N cross-section is usually reduced by correlations, a collective mode in the spin S = 1 channel may

L. Mornas; Avda Calvo Sotelo

2006-01-01

382

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

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

2014-10-20

383

We describe an apparatus for solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS) at 20–25 K and 9.4 Tesla. The MAS NMR probe uses helium to cool the sample space and nitrogen gas for MAS drive and bearings, as described earlier (Thurber et al., J. Magn. Reson. 2008) [1], but also includes a corrugated waveguide for transmission of microwaves from below the probe to the sample. With a 30 mW circularly polarized microwave source at 264 GHz, MAS at 6.8 kHz, and 21 K sample temperature, greater than 25-fold enhancements of cross-polarized 13C NMR signals are observed in spectra of frozen glycerol/water solutions containing the triradical dopant DOTOPA-TEMPO when microwaves are applied. As demonstrations, we present DNP-enhanced one-dimensional and two-dimensional 13C MAS NMR spectra of frozen solutions of uniformly 13C-labeled L-alanine and melittin, a 26-residue helical peptide that we have synthesized with four uniformly 13C-labeled amino acids. PMID:23238592

Thurber, Kent R.; Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

2012-01-01

384

Cavity-stimulated Raman emission from a single quantum dot spin

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

385

Resonant microwave cavity for 8.5Â12 GHz optically detected electron spin resonance with simultaneous nuclear magnetic resonance J. S. Colton1,a and L. R. Wienkes2 1 Department of Physics online 16 March 2009 We present a newly developed microwave resonant cavity for use in optically detected

Hart, Gus

386

Selective Excitation and Detection of Spin States in a Single Nanowire

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

387

Nuclear spin imaging with hyperpolarized nuclei created by brute force method

NASA Astrophysics Data System (ADS)

We have been developing a polarized HD target for particle physics at the SPring-8 under the leadership of the RCNP, Osaka University for the past 5 years. Nuclear polarizaton is created by means of the brute force method which uses a high magnetic field (~17 T) and a low temperature (~ 10 mK). As one of the promising applications of the brute force method to life sciences we started a new project, "NSI" (Nuclear Spin Imaging), where hyperpolarized nuclei are used for the MRI (Magnetic Resonance Imaging). The candidate nuclei with spin ½hslash are 3He, 13C, 15N, 19F, 29Si, and 31P, which are important elements for the composition of the biomolecules. Since the NMR signals from these isotopes are enhanced by orders of magnitudes, the spacial resolution in the imaging would be much more improved compared to the practical MRI used so far. Another advantage of hyperpolarized MRI is that the MRI is basically free from the radiation, while the problems of radiation exposure caused by the X-ray CT or PET (Positron Emission Tomography) cannot be neglected. In fact, the risk of cancer for Japanese due to the radiation exposure through these diagnoses is exceptionally high among the advanced countries. As the first step of the NSI project, we are developing a system to produce hyperpolarized 3He gas for the diagnosis of serious lung diseases, for example, COPD (Chronic Obstructive Pulmonary Disease). The system employs the same 3He/4He dilution refrigerator and superconducting solenoidal coil as those used for the polarized HD target with some modification allowing the 3He Pomeranchuk cooling and the following rapid melting of the polarized solid 3He to avoid the depolarization. In this report, the present and future steps of our project will be outlined with some latest experimental results.

Tanaka, Masayoshi; Kunimatsu, Takayuki; Fujiwara, Mamoru; Kohri, Hideki; Ohta, Takeshi; Utsuro, Masahiko; Yosoi, Masaru; Ono, Satoshi; Fukuda, Kohji; Takamatsu, Kunihiko; Ueda, Kunihiro; Didelez, Jean-P.; Prossati, Giorgio; de Waard, Arlette

2011-05-01

388

Nuclear Collisions Induced by Single-Cycle Laser Pulses:

NASA Astrophysics Data System (ADS)

Fusion occurs when light nuclei of hydrogen (H), deuterium (D), or tritium (T), join together to produce helium, neutrons, and energy. If harnessed on earth, fusion has the potential to provide a clean and virtually unlimited source of energy. The two present techniques for controlled fusion all rely on hot plasma. Thermal motion of the nuclei results in random nuclear collisions, which can be energetic enough to produce fusion when the temperature is high. We propose a ``new method'' which doesn't require preparation and confinement of hot and dense plasma, but works in a molecular gas. It uses the fact that nuclei in a molecule are pre-aligned in front of each other and can be driven into each other by the very strong and ultra-short laser pulse since the nuclei of different masses will acquire different velocities when driven by the same electric field. The nuclei may collide with high kinetic energy needed to overcome the Coulomb Barrier. These collisions may lead to fusion. Realization of this technique will require ultrashort (few-femtosecond, single-cycle) laser pulses with field intensities approaching 10^23W/cm^2. We have performed a classical simulation of nuclear motion under the action of the Coulomb repulsion and a strong laser field. We have also done a simple statistical ensemble calculation. From our results, we can see that collision will occur on a sub-attosecond time scale. On that timescale the nuclei will experience large acceleration and emit zeptosecond bursts of light.

Zhi, Miaochan; Sokolov, Alexei

2004-10-01

389

Nuclear Spin Relaxation of Deuterium Molecule in Deuterium Gas and in Solid Argon

NASA Astrophysics Data System (ADS)

Nuclear spin relaxation times have been measured for molecular deuterium, both as a pure gas and as a dilute impurity in a host matrix of solid argon. In the gas, T(,1) was measured as function of temperature and of the density (rho), over the ranges from 25 to 125 K and from 2 to 12 amagat. For the ortho species of the gas, the measurements were used to calculate T(,1)/(rho), which agreed with previous measurements by Hardy. The T(,1) measurements are consistent with a model of a primary relaxation mechanism resulting from an intramolecular interaction with the molecular angular momentum, which has fluctuating components because of collisions between gas molecules. Also, some measurements were made of the deuteron T(,1) in HD gas; only a small discrepancy from Hardy's results was observed. T(,1) and T(,2) of p-D(,2) were measured for dilute mixtures of molecular deuterium in solid argon at temperatures from 5.6 to 55 K. The mixtures were purposely dilute in order to reduce intermolecular interactions between deuterium molecules. The primary relaxation mechanism in these mixtures is, as for the gaseous samples, the intramolecular interaction with the fluctuating molecular spin; in this case, the molecular spin fluctuations are caused by phonon induced modulation of electric field gradients at the molecular sites. The results can described by Fedders' calculation of the intramolecular interaction, and by the Van Kronendank and Walker model of anharmonic phonon interactions with the molecular quadrupole moment. In addition, evidence for an additional relaxation mechanism was observed. This extra relaxation is probably the result of a direct interaction with the nuclear quadrupole moment. The field fluctuations which cause the direct relaxation are probably the result of molecular motions. The mixture samples were mixed in the liquid phase, and then frozen. T(,1) was also measured in the liquid mixtures, and line shape spectra were recorded. A shift of the deuterium resonance frequency was observed between gas phase and liquid phase mixtures. All of the relaxation time measurements were performed using pulsed NMR techniques, at a frequency of 55 MHz in a 8.5 T superconducting magnet. A liquid helium flow cryostat system was used to control the temperature of the samples. A general-purpose NMR spectrometer, designed and assembled by the author, was used to collect the NMR data.

Mohr, Gregory Alan

390

Fractionated Mercury Isotopes in Fish: The Effects of Nuclear Mass, Spin, and Volume

NASA Astrophysics Data System (ADS)

Mercury is long known as a common environmental contaminant. In methylated form it is even more toxic and the methylation process is facilitated by microbial activities. Methyl mercury easily crosses cell membrane and accumulates in soft tissues of fishes and finally biomagnifies with increasing trophic levels. Natural variations in the isotopic composition of mercury have been reported and such variations have emphasized mass dependent fractionations, while theory and laboratory experiments indicate that mass-independent isotopic fractionation (MIF) effects are likely to be found as well. This study focuses on the MIF of mercury isotopes in the soft tissues of fishes. Samples include both fresh water and marine fish, from different continents and oceans. Approximately 1 gm of fish soft tissue was dissolved in 5 ml of conc. aqua regia for 24 hrs and filtered through a ¬¬¬100 ?m filter paper and diluted with DI water. Hg is measured as a gaseous phase generated by reduction of the sample with SnCl2 in a continuous- flow cold-vapor generator connected to a Thermo-Finnigan Neptune MC-ICPMS. To minimize instrumental fractionation isotope ratios were measured by sample standard bracketing and reported as ?‰ relative to NIST SRM 3133 Hg standard where ?AHg = [(A Hg/202Hg)sample/(A Hg/202Hg)NIST313] -1 ×1000‰. In this study we have measured the isotope ratios 198Hg/202Hg, 199Hg/202Hg, 200Hg/202Hg, 201Hg/202Hg and 204Hg/202Hg. In all the fish samples ?198Hg, ?200Hg, ?202Hg, ?204Hg define a mass- dependent fractionation sequence, where as the ?199Hg and ?201Hg depart from the mass- dependent fractionation line and indicate an excess of the odd-N isotopes. The magnitude of the deviation (?AHg where A=199 or 201) as obtained by difference between the measured ?199Hg and ?201Hg of the samples and the value obtained by linear scaling defined by the even-N isotopes ranges from approximately 0.2 ‰ to 3‰. The ratios of ?199Hg /?201Hg range from 0.8 to 1.3, and thus more than one mass-independent isotope effect is inferred. MIF of mercury can be caused by the nuclear volume effect. Schauble, 2007 has calculated nuclear volume fractionation scaling factors for a number of common mercury chemical species in equilibrium with Hg° vapor. From his calculations the nuclear field shift effect is larger in ?199Hg than in ?201Hg by approximately a factor of two. The predominant mercury chemical species in fish is methylmercury cysteine. From the experimental studies of Buchachenko and others (2004) on the reaction of methylmercury chloride with creatine kinase it seems reasonable to predicted that the thiol functional groups of cysteine gets enriched in 199Hg and 201Hg. Here the magnetic isotope effect (MIE) produces a kinetic partial separation of isotopes with non-zero nuclear spin quantum numbers from the even-N isotopes. The ratio of enrichment of ?201Hg /?199Hg is predicted from theory to be 1.11, which is the ratio of the magnetic moments of 199Hg and 201Hg. Because mercury possesses two odd-N isotopes, it is possible to detect and evaluate the effects of two distinct, mass-independent isotope fractionating processes. From the data obtained on fish samples, we can deconvolute the contributions of the isotope effects of nuclear mass, spin and volume. For these samples the role of spin or the magnetic isotope effect is the most dominant.

Das, R.; Odom, A. L.

2007-12-01

391

NASA Astrophysics Data System (ADS)

Nuclear magnetic resonance (NMR) experiments with a spinning sample [magic angle sample spinning (MASS)] are used to remove the line broadening in composite systems, where the susceptibility contrast of its constituents gives rise to an inhomogeneous field that causes a line broadening and obscures chemical information. The NMR signal in these experiments has a phase and an amplitude part. In the absence of diffusion, i.e., in the MASS spectra of solids, the amplitude of the signal from an isochromat is a constant independent of position and time and the phase is a periodic function of the rotor frequency ?r. In fluids, the amplitude of a spin packet is a function of its position and time. The amplitude modulation and relaxation in diffusive MASS encodes the dynamics of motion and the landscape (geometry of pores and field gradients) probed by the motion. Here we use spin manipulation—total suppression of sidebands (TOSS)—to suppress the effects of phase with the goal of isolating the amplitude term. By the TOSS sequence the phase factor at time t for a spin packet at an azimuthal angle ? is made to depend on ? only as a function of ?rt-?, which suppresses the sidebands in solids upon an integration over ?. Due to molecular diffusion, the amplitude part depends on ?, and, thus, diffusive TOSS cannot suppress the sidebands. The residual sidebands carry the information of dynamics and pore and magnetic field geometry, in addition, by reducing the size of the sidebands, TOSS is of course, also useful in identifying various fluid components in situ. The diffusive MASS gives a measure of the spread in local fields and diffusive TOSS gives a measure of the spread in local gradients.

Liu, Yun; Leu, Gabriela; Singer, S.; Cory, D. G.; Sen, Pabitra N.

2001-04-01

392

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

393

We present a theoretical analysis of the competition between so-called nuclear Jacobi and Poincar\\'e shape transitions in function of spin - at high temperatures. The latter condition implies the method of choice - a realistic version of the nuclear Liquid Drop Model (LDM), here: the Lublin-Strasbourg Drop (LSD) model. We address specifically the fact that the Jacobi and Poincar\\'e shape transitions are accompanied by the flattening of total nuclear energy landscape as function of the relevant deformation parameters what enforces large amplitude oscillation modes that need to be taken into account. For that purpose we introduce an approximate form of the collective Schr\\"odinger equation whose solutions are used to calculate the most probable deformations associated with both types of transitions and discuss the physical consequences in terms of the associated critical-spin values and transitions themselves.

K. Mazurek; J. Dudek; A. Maj; D. Rouvel

2013-08-14

394

Continuous re-hyperpolarization of nuclear spins using parahydrogen: theory and experiment.

The continuous re-hyperpolarization of nuclear spins in the liquid state by means of parahydrogen (para-H2) and chemical exchange at low magnetic fields was recently discovered and offers intriguing perspectives for many varieties of magnetic resonance. In this contribution, we provide a theoretical assessment of this effect and compare the results to experimental data. A distinct distribution of polarization is found, which shares some features with experimental data and, interestingly, does not directly correspond to the loss of the singlet order of para-H2. We derived expressions for the magnetic field and para-H2-substrate interaction time, for which the polarization transfer is maximal. This work sheds light onto the effect of continuous hyperpolarization and elucidates the underlying mechanism, which may facilitate the development of an optimized catalyst. As an application, continuous hyperpolarization may enable highly sensitive nuclear magnetic resonance at very low magnetic fields, for example, for the cost-efficient screening of drugs. PMID:25079961

Hövener, Jan-Bernd; Knecht, Stephan; Schwaderlapp, Niels; Hennig, Jürgen; von Elverfeldt, Dominik

2014-08-25

395

NASA Astrophysics Data System (ADS)

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

Ginzburg, I. F.

2014-01-01

396

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

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

2005-01-14

397

We present 13 C high-resolution magic-angle-turning (MAT) and magic angle spinning nuclear magnetic resonance data of Cs and Rb intercalated single walled carbon nanotubes. We find two distinct phases at different intercalation levels. A simple charge transfer is applicable at low intercalation level. The new phase at high intercalation level is accompanied by a hybridization of alkali (s) orbitals with the carbon (sp2) orbitals of the single walled nanotubes, which indicate bundle surface sites is the most probable alkali site.

Bouhrara, M.; Saih, Y. [KAUST Catalysis Center (KCC) King Abdullah University of Science and Technology, Thuwal (Saudi Arabia); Waagberg, T. [Department of Physics, Umeaa University, 901 87 Umeaa (Sweden); Goze-Bac, C. [LCVN, Universite Montpellier II, Place E. Bataillon, 34095 Montpellier (France); Abou-Hamad, E. [KAUST Catalysis Center (KCC) King Abdullah University of Science and Technology, Thuwal (Saudi Arabia); Department of Physics, Umeaa University, 901 87 Umeaa (Sweden); LCVN, Universite Montpellier II, Place E. Bataillon, 34095 Montpellier (France)

2011-09-01

398

The Effects of Nuclear Fragmentation Models on Single Event Effect Prediction

There is a need for improved physics models to correctly predict single event effects (SEEs) caused by nuclear reaction products from heavy ion radiation. Previous validations for nuclear fragmentation simulations are shown to be insufficient to support SEE analysis applications. A comparison of different physics models with experimental nuclear physics data coupled with energy deposition predictions is presented.

Michael Andrew Clemens; Nathaniel A. Dodds; Robert A. Weller; Marcus H. Mendenhall; Robert A. Reed; Ronald D. Schrimpf; Tatsumi Koi; Dennis H. Wright; Makoto Asai

2009-01-01

399

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

NASA Astrophysics Data System (ADS)

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

Metelmann, A.; Brandes, T.

2012-12-01

400

Paramagnetic relaxation enhancement is often explored in magnetic resonance imaging in terms of contrast agents and in biomolecular nuclear magnetic resonance (NMR) spectroscopy for structure determination. New ultrahigh-spin clusters are investigated with respect to their NMR relaxation properties. As their molecular size and therefore motional correlation times as well as their electronic properties differ significantly from those of conventional contrast agents, questions about a comprehensive characterization arise. The relaxivity was studied by field-dependent longitudinal and transverse NMR relaxometry of aqueous solutions containing Fe(III) 10 Dy(III) 10 ultrahigh-spin clusters (spin ground state 100/2). The high-field limit was extended to 32.9 T by using a 24 MW resistive magnet and an ultrahigh-frequency NMR setup. Interesting relaxation dispersions were observed; the relaxivities increase up to the highest available fields, which indicates a complex interplay of electronic and molecular correlation times. PMID:25115895

Machado, Julyana R; Baniodeh, Amer; Powell, Annie K; Luy, Burkhard; Krämer, Steffen; Guthausen, Gisela

2014-11-10

401

The Spin Dependence of Nuclear Muon Capture by Laser Polarized HELIUM-3.

NASA Astrophysics Data System (ADS)

Using the muon beam at TRIUMF, we have made the first measurement of the spin dependence of the reaction: mu^- + ^3He tonu +^3H. This spin dependence is quite sensitive to the induced pseudoscalar form factor, F_{P}, a piece of the weak charged nuclear current of ^3He about which, experimentally, relatively little is known. The ratio of F_{P} to F _{A}, the axial vector form factor, is predicted by the partially conserved axial current hypothesis (PCAC) and the Goldberger-Treiman relation. Thus, a measurement of F_{P} will test our understanding of strong interactions at low energies. The rate of nuclear muon capture in ^3 He is proportional to (1+A_{v }P_{v} {rm cos} theta), where theta is the angle between the muon polarization and the direction of the triton recoil, P_{v} is the muon vector polarization and A_{v } is the vector analyzing power, a preliminary value for which is: A_{v} = .604 +/-.093(stat.)_sp{-142}{+112 }(system.). This value is in agreement with the PCAC prediction of: A_{v}=.524 +/-.006. A measure of the strength of our technique is that the raw forward/backward asymmetry in the triton recoil direction was measured to 11.5% of itself. The design, construction and operation of the device that served both as a polarized target and as a detector for the recoil tritons is the main emphasis of this thesis. The detector, a gridded ion chamber, was incorporated inside a 5 liter target that was filled with 8 atmospheres of ^3He, 100 torr of N_2, and 6 grams of Rb. Muons stopped in the target formed muonic helium atoms and were polarized by collisions with Rb atoms that were optically pumped with lasers. The ion chamber produced clean signals despite operating under the severe conditions required for optical pumping. The direction of the tritons was determined by fitting the shapes of the ionization pulses. Future improvements of our technique appear to provide the most promising avenue to improved understanding of the induced pseudoscalar coupling, F_ {P}, as well as the induced pseudoscalar coupling of the proton, g_{P}. .

Bogorad, Paul Lev

1995-01-01

402

NASA Astrophysics Data System (ADS)

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

Rostamzadeh Renani, Fatemeh; Kirczenow, George

2014-10-01

403

Nuclear spin relaxation of sodium cations in bacteriophage Pf1 solutions D. N. Sobieski, N. R The nuclear magnetic resonance NMR spectra for the I=3/2 23 Na cation dissolved into filamentous bacteriophage the 23 Na nuclear quadrupole moment and the electric field gradient produced by the negatively charged Pf

Augustine, Mathew P.

404

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

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

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

2014-08-13

405

NASA Astrophysics Data System (ADS)

This contribution focusses on recent measurements of nuclear moments and spins using two complementary methods. The ground state magnetic moments and spins of the exotic isotopes 49,51K have been measured at the ISOLDE facility at CERN using bunched-beam high-resolution collinear laser spectroscopy. The re-inversion of the ground state spin from I = 1/2 in 47,49K back to the normal I = 3/2 in 51K has been established. At GANIL (Caen, France) the quadrupole moment of the 33Al ground state has been measured using the continuous-beam ?-nuclear magnetic resonance method applied to a spin-polarized beam produced at the LISE fragment separator. The large value establishes a very mixed wave function with about equal amounts of normal and neutron particle-hole excited configurations contributing to its ground state wave function. This illustrates the transitional nature of isotopes at the border of the island-of-inversion.

Neyens, G.

2013-07-01

406

Ab initio design of spin-filters using single organic molecules

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

407

Nuclear spin dependence of the reaction of H(3)+ with H2. II. Experimental measurements.

The nuclear spin dependence of the chemical reaction H(3)(+)+ H(2) ? H(2)?+ H(3)(+) has been studied in a hollow cathode plasma cell. Multipass infrared direct absorption spectroscopy has been employed to monitor the populations of several low-energy rotational levels of ortho- and para-H(3)(+) (o-H(3)(+) and p-H(3)(+)) in hydrogenic plasmas of varying para-H(2) (p-H(2)) enrichment. The ratio of the rates of the proton hop (k(H)) and hydrogen exchange (k(E)) reactions ? ? k(H)/k(E) is inferred from the observed p-H(3)(+) fraction as a function of p-H(2) fraction using steady-state chemical models. Measurements have been performed both in uncooled (T(kin) ? 350 K) and in liquid-nitrogen-cooled (T(kin) ? 135 K) plasmas, marking the first time this reaction has been studied at low temperature. The value of ? has been found to decrease from 1.6 ± 0.1 at 350 K to 0.5 ± 0.1 at 135 K. PMID:21599063

Crabtree, Kyle N; Kauffman, Carrie A; Tom, Brian A; Beçka, Eftalda; McGuire, Brett A; McCall, Benjamin J

2011-05-21

408

Breit interaction effects in relativistic theory of the nuclear spin-rotation tensor

NASA Astrophysics Data System (ADS)

In this work, relativistic effects on the nuclear spin-rotation (SR) tensor originated in the electron-nucleus and electron-electron Breit interactions are analysed. To this end, four-component numerical calculations were carried out in model systems HX (X=H,F,Cl,Br,I). The electron-nucleus Breit interaction couples the electrons and nuclei dynamics giving rise to a purely relativistic contribution to the SR tensor. Its leading order in 1/c is of the same value as that of relativistic corrections on the usual second order expression of the SR tensor considered in previous work [I. A. Aucar, S. S. Gómez, J. I. Melo, C. G. Giribet, and M. C. Ruiz de Azúa, J. Chem. Phys. 138, 134107 (2013)], and therefore it is absolutely necessary to establish its relative importance. For the sake of completeness, the corresponding effect originating in the electron-electron Breit interaction is also considered. It is verified that in all cases these Breit interactions yield only very small corrections to the SR tensors of both the X and H nuclei in the present series of compounds. Results of the present work strongly suggest that in order to achieve experimental accuracy in the theoretical study of the SR tensor both electron-nucleus and electron-electron Breit effects can be safely neglected.

Aucar, I. Agustín; Gómez, Sergio S.; Giribet, Claudia G.; Ruiz de Azúa, Martín C.

2013-09-01

409

Breit interaction effects in relativistic theory of the nuclear spin-rotation tensor.

In this work, relativistic effects on the nuclear spin-rotation (SR) tensor originated in the electron-nucleus and electron-electron Breit interactions are analysed. To this end, four-component numerical calculations were carried out in model systems HX (X=H,F,Cl,Br,I). The electron-nucleus Breit interaction couples the electrons and nuclei dynamics giving rise to a purely relativistic contribution to the SR tensor. Its leading order in 1/c is of the same value as that of relativistic corrections on the usual second order expression of the SR tensor considered in previous work [I. A. Aucar, S. S. Go?mez, J. I. Melo, C. G. Giribet, and M. C. Ruiz de Azu?a, J. Chem. Phys. 138, 134107 (2013)], and therefore it is absolutely necessary to establish its relative importance. For the sake of completeness, the corresponding effect originating in the electron-electron Breit interaction is also considered. It is verified that in all cases these Breit interactions yield only very small corrections to the SR tensors of both the X and H nuclei in the present series of compounds. Results of the present work strongly suggest that in order to achieve experimental accuracy in the theoretical study of the SR tensor both electron-nucleus and electron-electron Breit effects can be safely neglected. PMID:24028107

Aucar, I Agustín; Gómez, Sergio S; Giribet, Claudia G; Ruiz de Azúa, Martín C

2013-09-01

410

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

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

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

2013-09-01

411

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

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

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

2013-04-29

412

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

413

Electrical control of quantum dot spin qubits

NASA Astrophysics Data System (ADS)

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

Laird, Edward Alexander

414

We discuss methods of quantum state tomography for solid-state systems with a large nuclear spin $I=3/2$ in nanometer-scale semiconductors devices based on a quantum well. Due to quadrupolar interactions, the Zeeman levels of these nuclear-spin devices become nonequidistant, forming a controllable four-level quantum system (known as quartit or ququart). The occupation of these levels can be selectively and coherently manipulated by multiphoton transitions using the techniques of nuclear magnetic resonance (NMR) [Yusa et al., Nature (London) 434, 101 (2005)]. These methods are based on an unconventional approach to NMR, where the longitudinal magnetization $M_z$ is directly measured. This is in contrast to the standard NMR experiments and tomographic methods, where the transverse magnetization $M_{xy}$ is detected. The robustness against errors in the measured data is analyzed by using condition numbers. We propose several methods with optimized sets of rotations. The optimization is applied to decrease the number of NMR readouts and to improve the robustness against errors, as quantified by condition numbers. An example of state reconstruction, using Monte Carlo methods, is presented. Tomographic methods for quadrupolar nuclei with higher-spin numbers (including $I=7/2$) are also described.

Adam Miranowicz; Sahin K. Ozdemir; Jiri Bajer; Go Yusa; Nobuyuki Imoto; Yoshiro Hirayama; Franco Nori

2014-10-09

415

The derivation, implementation, and validation of a new approximation to the two-electron spin–orbit coupling (SOC) terms is reported. The approximation, referred to as flexible nuclear screening spin–orbit, is based on the effective one-electron spin–orbit operator and accounts for two-electron SOC effects by screening nuclear charges. A highly flexible scheme for the nuclear screening is developed, mainly using parameterization based on ab initio atomic SOC calculations. Tabulated screening parameters are provided for contracted and primitive Gaussian-type basis functions of the ANO-RCC basis set for elements from H to Cm. The strategy for their adaptation to any other Gaussian basis set is presented and validated. A model to correct for the effect of splitting of transition metal d orbitals on their SOC matrix elements is introduced. The method is applied to a representative set of molecules, and compared to exact treatment and other approximative approaches at the same level of relativistic theory. The calculated SOC matrix elements are in very good agreement with their “exact” values; deviation below 1% is observed on average. The presented approximation is considered to be generally applicable, simple to implement, highly efficient, and accurate.

Chalupský, Jakub, E-mail: jakub@ims.ac.jp; Yanai, Takeshi [Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki, Aichi 444-8585 (Japan)] [Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki, Aichi 444-8585 (Japan)

2013-11-28