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1

Coherent control of a single ^{29}si nuclear spin qubit.

Magnetic fluctuations caused by the nuclear spins of a host crystal are often the leading source of decoherence for many types of solid-state spin qubit. In group-IV semiconductor materials, the spin-bearing nuclei are sufficiently rare that it is possible to identify and control individual host nuclear spins. This Letter presents the first experimental detection and manipulation of a single ^{29}Si nuclear spin. The quantum nondemolition single-shot readout of the spin is demonstrated, and a Hahn echo measurement reveals a coherence time of T_{2}=6.3(7)??ms-in excellent agreement with bulk experiments. Atomistic modeling combined with extracted experimental parameters provides possible lattice sites for the ^{29}Si atom under investigation. These results demonstrate that single ^{29}Si nuclear spins could serve as a valuable resource in a silicon spin-based quantum computer. PMID:25541792

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

2014-12-12

2

Coherent Control of a Single 29Si Nuclear Spin Qubit

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

3

Coherent Control of a Single Silicon-29 Nuclear Spin Qubit

Magnetic fluctuations caused by the nuclear spins of a host crystal are often the leading source of decoherence for many types of solid-state spin qubit. In group-IV materials, the spin-bearing nuclei are sufficiently rare that it is possible to identify and control individual host nuclear spins. This work presents the first experimental detection and manipulation of a single $^{29}$Si nuclear spin. The quantum non-demolition (QND) single-shot readout of the spin is demonstrated, and a Hahn echo measurement reveals a coherence time of $T_2 = 6.3(7)$ ms - in excellent agreement with bulk experiments. Atomistic modeling combined with extracted experimental parameters provides possible lattice sites for the $^{29}$Si atom under investigation. These results demonstrate that single $^{29}$Si nuclear spins could serve as a valuable resource in a silicon spin-based quantum computer.

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

2014-08-06

4

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

5

Nuclear magnetic resonance spectroscopy with single spin sensitivity.

Nuclear magnetic resonance spectroscopy and magnetic resonance imaging at the ultimate sensitivity limit of single molecules or single nuclear spins requires fundamentally new detection strategies. The strong coupling regime, when interaction between sensor and sample spins dominates all other interactions, is one such strategy. In this regime, classically forbidden detection of completely unpolarized nuclei is allowed, going beyond statistical fluctuations in magnetization. Here we realize strong coupling between an atomic (nitrogen-vacancy) sensor and sample nuclei to perform nuclear magnetic resonance on four (29)Si spins. We exploit the field gradient created by the diamond atomic sensor, in concert with compressed sensing, to realize imaging protocols, enabling individual nuclei to be located with Angstrom precision. The achieved signal-to-noise ratio under ambient conditions allows single nuclear spin sensitivity to be achieved within seconds. PMID:25146503

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

2014-01-01

6

Nuclear magnetic resonance spectroscopy with single spin sensitivity

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. PMID:25146503

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.

2014-01-01

7

Single shot NMR on single, dark nuclear spins

The electron and nuclear spins associated with the nitrogen-vacancy (NV) center in diamond are supposed to be building blocks for quantum computing devices and nanometer scale magnetometry operating under ambient conditions. For every such building block precise knowledge of the involved quantum states is crucial. Especially for solid state systems the corresponding hilbert space can be large. Here, we experimentally show that under usual operating conditions the NV color center exists in an equilibrium of two charge states (i.e. 70% in the usually used negative (NV-) and 30% in the neutral one (NV0)). Projective quantum non-demolition measurement of the nitrogen nuclear spin enables the detection even of the additional, optically inactive state. It turns out that the nuclear spin can be coherently driven also in NV0. However, its T1 ~ 90 ms and T2 ~ 6micro-s times are much shorter than in NV-, supposedly because of the dynamic Jahn-Teller effect.

Waldherr, G; Steiner, M; Neumann, P; Gali, A; Jelezko, F; Wrachtrup, J

2010-01-01

8

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

NASA Astrophysics Data System (ADS)

For a III-V semiconductor quantum dot charged with a single hole, we investigate the feedback control of the nuclear spin bath through dynamical nuclear spin polarization. The scheme utilizes the hole-nuclear flip-flop by their anisotropic hyperfine interaction, where the flip direction of the nuclear spin can be conditioned on the sign of the overall hyperfine field through initialization processes that do not involve explicit measurement. We show that a negative feedback can be implemented to suppress the statistical fluctuations of the nuclear hyperfine field for enhancing the coherence time of the hole spin qubit. Positive feedback can prepare the nuclear spin ensemble into states where the nuclear hyperfine field distribution has two well separated peaks, realizing a quantum heat bath that cannot be described by a single effective temperature.

Pang, Hongliang; Gong, Zhirui; Yao, Wang

2015-01-01

9

Single shot NMR on single, dark nuclear spins

The electron and nuclear spins associated with the nitrogen-vacancy (NV)\\u000acenter in diamond are supposed to be building blocks for quantum computing\\u000adevices and nanometer scale magnetometry operating under ambient conditions.\\u000aFor every such building block precise knowledge of the involved quantum states\\u000ais crucial. Especially for solid state systems the corresponding hilbert space\\u000acan be large. Here, we experimentally

G. Waldherr; J. Beck; M. Steiner; P. Neumann; A. Gali; F. Jelezko; J. Wrachtrup

2010-01-01

10

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

High-dynamic-range magnetometry with a single nuclear spin in diamond G. Waldherr1 *, J. Beck1 , P, we implement a quantum phase estimation algorithm6Â8 on a single nuclear spin in diamond to combine coherence times4 , even at ambient conditions, and coherent coupling to nearby nuclear spins11,12 . Its

Pfeifer, Holger

11

Single crystal nuclear magnetic resonance in spinning powders

NASA Astrophysics Data System (ADS)

We present a method for selectively exciting nuclear magnetic resonances (NMRs) from well-defined subsets of crystallites from a powdered sample under magic angle spinning. Magic angle spinning induces a time dependence in the anisotropic interactions, which results in a time variation of the resonance frequencies which is different for different crystallite orientations. The proposed method exploits this by applying selective pulses, which we refer to as XS (for crystallite-selective) pulses, that follow the resonance frequencies of nuclear species within particular crystallites, resulting in the induced flip angle being orientation dependent. By selecting the radiofrequency field to deliver a 180 ? pulse for the target orientation and employing a train of such pulses combined with cogwheel phase cycling, we obtain a high degree of orientational selectivity with the resulting spectrum containing only contributions from orientations close to the target. Typically, this leads to the selection of between 0.1% and 10% of the crystallites, and in extreme cases to the excitation of a single orientation resulting in single crystal spectra of spinning powders. Two formulations of this method are described and demonstrated with experimental examples on [1 - 13C]-alanine and the paramagnetic compound Sm2Sn2O7.

Pell, Andrew J.; Pintacuda, Guido; Emsley, Lyndon

2011-10-01

12

Hyperfine switching triggered by resonant tunneling for the detection of a single nuclear spin qubit

A novel detection mechanism and a robust control of a single nuclear spin-flip by hyperfine interactions between the nuclear spin and tunneling electron spin are proposed on the basis of ab initio non-equilibrium Green's function calculations. The calculated relaxation times of the nuclear spin of proton in a nano-contact system, Pd(electrode)–H2–Pd(electrode), show that ON\\/OFF switching of hyperfine interactions is effectively

Tomofumi Tada

2008-01-01

13

Dynamic Nuclear Polarization with Single Electron Spins J. R. Petta,1,2

polarization driven by scattering between spin-polarized edge states induced hys- teresis in conductanceDynamic Nuclear Polarization with Single Electron Spins J. R. Petta,1,2 J. M. Taylor,1,3 A. C Barbara, California 93106, USA (Received 6 September 2007; published 11 February 2008) We polarize nuclear

Petta, Jason

14

A novel approach for measurement of single electron and nuclear spin states is suggested. Our approach is based on optically detected magnetic resonance in a nano-probe located at the apex of an AFM tip. The method provides single electron spin sensitivity with nano-scale spatial resolution.

Gennady P Berman; Alan R Bishop; Boris M Chernobrod; Marilyn E Hawley; Geoffrey W Brown; Vladimir I Tsifrinovich

2006-01-01

15

Sensing single nuclear spins is a central challenge in magnetic resonance based imaging techniques. Although different methods and especially diamond defect based sensing and imaging techniques in principle have shown sufficient sensitivity, signals from single nuclear spins are usually too weak to be distinguished from background noise. Here, we present the detection and identification of remote single C-13 nuclear spins embedded in nuclear spin baths surrounding a single electron spins of a nitrogen-vacancy centre in diamond. With dynamical decoupling control of the centre electron spin, the weak magnetic field ~10 nT from a single nuclear spin located ~3 nm from the centre with hyperfine coupling as weak as ~500 Hz is amplified and detected. The quantum nature of the coupling is confirmed and precise position and the vector components of the nuclear field are determined. Given the distance over which nuclear magnetic fields can be detected the technique marks a firm step towards imaging, detecting and cont...

Zhao, Nan; Schmid, Berhard; Isoya, Junichi; Markham, Mathew; Twitchen, Daniel; Jelezko, Fedor; Liu, Ren-Bao; Fedder, Helmut; Wrachtrup, Jörg

2012-01-01

16

We demonstrate fast universal electrical spin manipulation with inhomogeneous magnetic fields. With fast Rabi frequency up to 127 MHz, we leave the conventional regime of strong nuclear-spin influence and observe a spin-flip fidelity >96%, a distinct chevron Rabi pattern in the spectral-time domain, and a spin resonance linewidth limited by the Rabi frequency, not by the dephasing rate. In addition, we establish fast z rotations up to 54 MHz by directly controlling the spin phase. Our findings will significantly facilitate tomography and error correction with electron spins in quantum dots. PMID:25615383

Yoneda, J; Otsuka, T; Nakajima, T; Takakura, T; Obata, T; Pioro-Ladrière, M; Lu, H; Palmstrøm, C J; Gossard, A C; Tarucha, S

2014-12-31

17

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

18

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

19

Sensing single nuclear spins is a central challenge in magnetic resonance based imaging techniques. Although different methods and especially diamond defect based sensing and imaging techniques in principle have shown sufficient sensitivity, signals from single nuclear spins are usually too weak to be distinguished from background noise. Here, we present the detection and identification of remote single C-13 nuclear spins embedded in nuclear spin baths surrounding a single electron spins of a nitrogen-vacancy centre in diamond. With dynamical decoupling control of the centre electron spin, the weak magnetic field ~10 nT from a single nuclear spin located ~3 nm from the centre with hyperfine coupling as weak as ~500 Hz is amplified and detected. The quantum nature of the coupling is confirmed and precise position and the vector components of the nuclear field are determined. Given the distance over which nuclear magnetic fields can be detected the technique marks a firm step towards imaging, detecting and controlling nuclear spin species external to the diamond sensor.

Nan Zhao; Jan Honert; Berhard Schmid; Junichi Isoya; Mathew Markham; Daniel Twitchen; Fedor Jelezko; Ren-Bao Liu; Helmut Fedder; Jörg Wrachtrup

2012-04-29

20

Fast room-temperature phase gate on a single nuclear spin in diamond.

Nuclear spins support long lived quantum coherence due to weak coupling to the environment, but are difficult to rapidly control using nuclear magnetic resonance as a result of the small nuclear magnetic moment. We demonstrate a fast ?500??ns nuclear spin phase gate on a (14)N nuclear spin qubit intrinsic to a nitrogen-vacancy center in diamond. The phase gate is enabled by the hyperfine interaction and off-resonance driving of electron spin transitions. Repeated applications of the phase gate bang-bang decouple the nuclear spin from the environment, locking the spin state for up to ?140???s. PMID:25062156

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

2014-07-11

21

NASA Astrophysics Data System (ADS)

A new class of nuclear magnetic resonance (NMR) pulses that provides simultaneous spatially selective inversion of nuclear spins in two dimensions following a single pulse application is described and demonstrated. The two-dimensional selective pulses consist of a single square- or amplitude-modulated ? rf pulse applied in the presence of an amplitude-modulated magnetic field gradient that reorients through the two dimensions during the rf pulse. For example, square and Gaussian rf pulses produce sharply peaked sombrero-, egg-carton-, and stalagmite-shaped profiles of spin inversion in the xz plane when applied in the presence of a gradient that rotates or describes a figure eight in the xz plane. The theoretical profiles, computed by numerical integration of the Bloch equation, are in good agreement with experimental results obtained by incorporating the pulses into a conventional NMR imaging sequence. The pulses are directly applicable to restricted field-of-view high-resolution imaging for the amelioration of aliasing signal artifacts, and when combined with one-dimensional localized phosphorus (31P) chemical shift spectroscopy techniques that employ surface detection coils, should permit complete three-dimensionally localized 31P NMR spectroscopy. The ? pulses provide similar two-dimensional spatial selectivity of the transverse nuclear magnetization when used for refocusing Hahn spin echoes.

Bottomley, Paul A.; Hardy, Christopher J.

1987-11-01

22

Optical pumping of the electronic and nuclear spin of single charge-tunable quantum dots.

We present a comprehensive examination of optical pumping of spins in individual GaAs quantum dots as we change the net charge from positive to neutral to negative with a charge-tunable heterostructure. Negative photoluminescence polarization memory is enhanced by optical pumping of ground state electron spins, which we prove with the first measurements of the Hanle effect on an individual quantum dot. We use the Overhauser effect in a high longitudinal magnetic field to demonstrate efficient optical pumping of nuclear spins for all three charge states of the quantum dot. PMID:15783594

Bracker, A S; Stinaff, E A; Gammon, D; Ware, M E; Tischler, J G; Shabaev, A; Efros, Al L; Park, D; Gershoni, D; Korenev, V L; Merkulov, I A

2005-02-01

23

Teleportation in a nuclear spin quantum computer

We present a procedure for quantum teleportation in a nuclear spin quantum computer in which quantum logic gates are implemented by using selective electromagnetic pulses. A sequence of pulses is combined with single-spin measurements in the sigmaz basis for fast transfer of information in a spin quantum computer. We simulated this procedure for quantum teleportation in a nuclear spin chain

Gennady P. Berman; Gustavo V. López; Vladimir I. Tsifrinovich

2002-01-01

24

. Terbium Double-Decker 1 S3. Nuclear Spin Read-Out 2 S4. Quantum Tunnelling of Magnetization 3 S5. Quantum magnetic field sweeps in three dimensions at field sweep rates up to 0.2 T/s. S2. TERBIUM DOUBLE-DECKER We used a Terbium (III) bis-phthalocyanine single molecule magnet (SMM), which is a metal-organic com

25

NASA Astrophysics Data System (ADS)

A multiterminal device based on a carbon nanotube quantum dot was used at very low temperature to probe a single electronic and nuclear spin embedded in a bis-(phthalocyaninato) terbium (III) complex (TbPc2). A spin-valve signature with large conductance jumps was found when two molecules were strongly coupled to the nanotube. The application of a transverse field separated the magnetic signal of both molecules and enabled single-shot read-out of the terbium nuclear spin. The Landau-Zener (LZ) quantum tunneling probability was studied as a function of field sweep rate, establishing a good agreement with the LZ equation and yielding the tunnel splitting ?. It was found that ? increased linearly as a function of the transverse field. These studies are an essential prerequisite for the coherent manipulation of a single nuclear spin in TbPc2.

Urdampilleta, M.; Klyatskaya, S.; Ruben, M.; Wernsdorfer, W.

2013-05-01

26

Electron Spin Decoherence in Silicon Carbide Nuclear Spin Bath

In this paper, we study the electron spin decoherence of single defects in silicon carbide (SiC) nuclear spin bath. We find that, although the natural abundance of $^{29}\\rm{Si}$ ($p_{\\rm{Si}}=4.7\\%$) is about 4 times larger than that of $^{13}{\\rm C}$ ($p_{\\rm{C}}=1.1\\%$), the electron spin coherence time of defect centers in SiC nuclear spin bath in strong magnetic field ($B>300~\\rm{Gauss}$) is longer than that of nitrogen-vacancy (NV) centers in $^{13}{\\rm C}$ nuclear spin bath in diamond. The reason for this counter-intuitive result is the suppression of heteronuclear-spin flip-flop process in finite magnetic field. Our results show that electron spin of defect centers in SiC are excellent candidates for solid state spin qubit in quantum information processing.

Li-Ping Yang; Christian Burk; Mattias Widmann; Sang-Yun Lee; Jörg Wrachtrup; Nan Zhao

2014-09-16

27

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

28

Nuclear spin circular dichroism

Recent years have witnessed a growing interest in magneto-optic spectroscopy techniques that use nuclear magnetization as the source of the magnetic field. Here we present a formulation of magnetic circular dichroism (CD) due to magnetically polarized nuclei, nuclear spin-induced CD (NSCD), in molecules. The NSCD ellipticity and nuclear spin-induced optical rotation (NSOR) angle correspond to the real and imaginary parts, respectively, of (complex) quadratic response functions involving the dynamic second-order interaction of the electron system with the linearly polarized light beam, as well as the static magnetic hyperfine interaction. Using the complex polarization propagator framework, NSCD and NSOR signals are obtained at frequencies in the vicinity of optical excitations. Hartree-Fock and density-functional theory calculations on relatively small model systems, ethene, benzene, and 1,4-benzoquinone, demonstrate the feasibility of the method for obtaining relatively strong nuclear spin-induced ellipticity and optical rotation signals. Comparison of the proton and carbon-13 signals of ethanol reveals that these resonant phenomena facilitate chemical resolution between non-equivalent nuclei in magneto-optic spectra.

Vaara, Juha, E-mail: juha.vaara@iki.fi [NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, FIN-90014 Oulu (Finland)] [NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, FIN-90014 Oulu (Finland); Rizzo, Antonio [Istituto per i Processi Chimico-Fisici del Consiglio Nazionale delle Ricerche (IPCF-CNR), Area della Ricerca, via G. Moruzzi 1, I-56124 Pisa (Italy)] [Istituto per i Processi Chimico-Fisici del Consiglio Nazionale delle Ricerche (IPCF-CNR), Area della Ricerca, via G. Moruzzi 1, I-56124 Pisa (Italy); Kauczor, Joanna; Norman, Patrick [Department of Physics, Chemistry and Biology, Linköping University, S-58183 Linköping (Sweden)] [Department of Physics, Chemistry and Biology, Linköping University, S-58183 Linköping (Sweden); Coriani, Sonia, E-mail: coriani@units.it [Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, Via L. Giorgieri 1, I-34127 Trieste (Italy)] [Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, Via L. Giorgieri 1, I-34127 Trieste (Italy)

2014-04-07

29

We theoretically study the decoherence and the dynamical decoupling control of nitrogen-vacancy center electron spins in high-purity diamond, where the hyperfine interaction with $^{13}$C nuclear spins is the dominating decoherence mechanism. The decoherence is formulated as the entanglement between the electron spin and the nuclear spins, which is induced by nuclear spin bath evolution conditioned on the electron spin state. The nuclear spin bath evolution is driven by elementary processes such as single spin precession and pairwise flip-flops. The importance of different elementary processes in the decoherence depends on the strength of the external magnetic field.

Zhao, Nan; Liu, Ren-Bao

2011-01-01

30

We theoretically study the decoherence and the dynamical decoupling control of nitrogen-vacancy center electron spins in high-purity diamond, where the hyperfine interaction with $^{13}$C nuclear spins is the dominating decoherence mechanism. The decoherence is formulated as the entanglement between the electron spin and the nuclear spins, which is induced by nuclear spin bath evolution conditioned on the electron spin state. The nuclear spin bath evolution is driven by elementary processes such as single spin precession and pairwise flip-flops. The importance of different elementary processes in the decoherence depends on the strength of the external magnetic field.

Nan Zhao; Sai-Wah Ho; Ren-Bao Liu

2011-08-11

31

NASA Astrophysics Data System (ADS)

We present an extensive nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) study of the normal state ( T> Tc) of an YBa 1.93Sr 0.07Cu 3O 6.92 single crystal ( Tc=90 K). The NMR data is interpreted using a model for the imaginary part of the dynamical electron spin susceptibility ??( q, ?) that is consistent with the inelastic neutron scattering (INS) experiments (carried out on the same sample investigated here): the q-dependence is assumed to be Gaussian (commensurate), with short and T independent coherence length ?. This model enabled us to perform a quantitative analysis of the planar copper spin-lattice and spin-spin relaxation rates which evidenced that a spin pseudogap starts to open at T*?130 K, confirming the INS results. Moreover, we show that the AF fluctuations contribution to yttrium relaxation is not negligible due to the dipolar coupling of the yttrium with the neighboring copper spins. The main signature of this feature is that a relation K??T1T=const does not hold for the yttrium site at higher temperatures. Our main conclusion is that, in order to explain the yttrium (and the planar oxygen) relaxation coherently with the INS results and the widely accepted one-band picture, the characteristic energy ?0 of the spin dynamics near q=0 must be strongly T dependent, otherwise the one-band description is not feasible. All the NMR results are interpreted within the ionic model of the hyperfine Hamiltonian taking into account the anisotropy of the g-factor and the static spin susceptibility ?s.

Auler, T.; Horvatic, M.; Gillet, J. A.; Berthier, C.; Berthier, Y.; Carretta, P.; Kitaoka, Y.; Ségransan, P.; Henry, J. Y.

1999-02-01

32

The main theme of this thesis is the hyperfine interaction between the many lattice nuclear spins and electron spins localized in GaAs quantum dots. This interaction is an intrinsic property of the material. Despite the fact that this interaction is rather weak, it can, as shown in this thesis, strongly influence the dynamics of electron spins in quantum dots. In

S. I. Erlingsson

2003-01-01

33

Electron spin decoherence in silicon carbide nuclear spin bath

NASA Astrophysics Data System (ADS)

In this Rapid Communication, we study the electron spin decoherence of single defects in silicon carbide (SiC) nuclear spin bath. We find that, although the natural abundance of 29Si (pSi=4.7 % ) is about four times larger than that of 13C (pC=1.1 % ), the electron spin coherence time of defect centers in SiC nuclear spin bath in a strong magnetic field (B >300 G ) is longer than that of nitrogen-vacancy (NV) centers in 13C nuclear spin bath in diamond. In addition to the smaller gyromagnetic ratio of 29Si, and the larger bond length in SiC lattice, a crucial reason for this counterintuitive result is the suppression of the heteronuclear-spin flip-flop process in a finite magnetic field. Our results show that electron spin of defect centers in SiC are excellent candidates for solid state spin qubit in quantum information processing.

Yang, Li-Ping; Burk, Christian; Widmann, Matthias; Lee, Sang-Yun; Wrachtrup, Jörg; Zhao, Nan

2014-12-01

34

I. Introduction 566 II. NSR energy levels and frequencies 568 1. Energy levels for resonating nuclei with spins 1 or 3\\/2 568 2. NSR energy levels for spin 5\\/2 571 III. Relative intensities of NSR lines 571 1. Relative intensities of Zeeman components in NQR 571 2. Generalized NSR equations 572 3. Relative intensities of NSR lines for spin 1

Vadim S Grechishkin; N. E. Ajnbinder

1964-01-01

35

Robust control of individual nuclear spins in diamond

Isolated nuclear spins offer a promising building block for quantum information processing systems, but their weak interactions often impede preparation, control, and detection. Hyperfine coupling to a proximal electronic spin can enhance each of these processes. Using the electronic spin of the nitrogen-vacancy center as an intermediary, we demonstrate robust initialization, single-qubit manipulation, and direct optical readout of 13C, 15N, and 14N nuclear spins in diamond. These results pave the way for nitrogen nuclear spin based quantum information architectures in diamond.

Benjamin Smeltzer; Jean McIntyre; Lilian Childress

2009-09-22

36

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

37

Quark Correlations and Single-Spin Asymmetries

Quark Correlations and Single-Spin Asymmetries Matthias Burkardt burkardt@nmsu.edu New Mexico State University Las Cruces, NM, 88003, U.S.A. Quark Correlations and Single-Spin Asymmetries Â p.1 Implications for nucleon structure Summary Quark Correlations and Single-Spin Asymmetries Â p.2/38 #12;What

38

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

39

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

40

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

41

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

42

Electrons trapped in single crystals of sucrose: Induced spin densities

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

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

1990-07-01

43

The first experiments on nuclear quadrupole interactions in crystals ; were carried out by R. V. Pound (Phys. Rev., magnetic resonance lines and by H. ; G. Dehmelt and H. Kruger (Naturwiss., 37: 111(1950)) who observed the absorption ; of radiowaves in a neutral magnetic field. The work was subsequently continued ; in two directions: toward the study of large,

V. S. Grechishkin; N. E. Ainbinder

1963-01-01

44

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

45

Single-shot readout of an electron spin in silicon.

The size of silicon transistors used in microelectronic devices is shrinking to the level at which quantum effects become important. Although 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 silicon can represent a well-isolated quantum bit with long coherence times because of the weak spin-orbit coupling and the possibility of eliminating nuclear spins from the bulk crystal. However, the control of single electrons in silicon has proved challenging, and so far the observation and manipulation of a single spin has been impossible. Here we report the demonstration of single-shot, time-resolved readout of an electron spin in silicon. 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 of ?6?seconds at a magnetic field of 1.5?tesla, and achieved a spin readout fidelity better than 90 per cent. High-fidelity single-shot spin readout in silicon opens the way to the development of a new generation of quantum computing and spintronic devices, built using the most important material in the semiconductor industry. PMID:20877281

Morello, Andrea; Pla, Jarryd J; Zwanenburg, Floris A; Chan, Kok W; Tan, Kuan Y; Huebl, Hans; Möttönen, 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

2010-10-01

46

Spin injection and transport in single layer graphene spin valves

NASA Astrophysics Data System (ADS)

Graphene is an attractive material for spintronics due to its tunable carrier concentration and polarity, weak spin-orbit coupling, and the prediction of novel spin-dependent behavior. We investigate the spin injection and transport in single layer graphene (SLG) spin valves at room temperature. Raman spectroscopy is used to identify SLG. SLG spin valve devices are fabricated by growing cobalt electrodes, defined by electron beam lithography, on top of SLG. Nonlocal resistance measurements are performed on these SLG spin valve devices in order to study the spin injection and transport properties. Our results show that the nonlocal magnetoresistance (MR) is dependent on the gate voltage. Also, the nonlocal MR shows some variation as a function of DC bias current.

Han, Wei; Wang, Wei-Hua; Pi, Keyu; McCreary, Kathy; Bao, Wenzhong; Li, Yan; Lau, Chun Ning; Kawakami, Roland

2009-03-01

47

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

48

Coherent properties of single rare-earth spin qubits

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

49

Coherent properties of single rare-earth spin qubits.

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

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

2014-01-01

50

Long coherence of electron spins coupled to a nuclear spin bath

Qubits, the quantum mechanical bits required for quantum computing, must retain their fragile quantum states over long periods of time. In many types of electron spin qubits, the primary source of decoherence is the interaction between the electron spins and nuclear spins of the host lattice. For electrons in gate defined GaAs quantum dots, previous spin echo measurements have revealed coherence times of about 1 $\\mu$s at low magnetic fields below 100 mT. Here, we show that coherence in such devices can actually survive to much longer times, and provide a detailed understanding of the measured nuclear spin induced decoherence. At fields above a few hundred millitesla, the coherence time measured using a single-pulse spin echo extends to 30 $\\mu$s. At lower magnetic fields, the echo first collapses, but then revives at later times given by the period of the relative Larmor precession of different nuclear species. This behavior was recently predicted, and as we show can be quantitatively accounted for by a semi-classical model for the electron spin dynamics in the presence of a nuclear spin bath. Using a multiple-pulse Carr-Purcell-Meiboom-Gill echo sequence, the decoherence time can be extended to more than 200 $\\mu$s, which represents an improvement by two orders of magnitude compared to previous measurements. This demonstration of effective methods to mitigate nuclear spin induced decoherence puts the quantum error correction threshold within reach.

Hendrik Bluhm; Sandra Foletti; Izhar Neder; Mark Rudner; Diana Mahalu; Vladimir Umansky; Amir Yacoby

2010-05-17

51

Electron correlation effects on nuclear magnetic resonance spin-spin coupling constant calculations

The chemical shifts and nuclear spin-spin coupling constants measured in nuclear magnetic resonance (NMR) experiments are related to the structure and conformation of molecules and consequently, NMR spectroscopy is an invaluable tool to practicing chemists. Accurate measurement of NMR chemical shifts and correlating spin-spin coupling constants and hence, chemical shifts are more widely used. However, NMR spin-spin coupling constants are also equally valuable. Correlating experimentally determined spin-spin coupling constants are also equally valuable. Correlating experimentally determined spin-spin coupling constants to molecular structures requires theoretical support and consequently having reliable and accurate theoretically calculated NMR spin-spin coupling constants is an important component of using experimentally determined spin-spin coupling constants. This work involves development and implementation of equation-of-motion coupled cluster singles and doubles (EOM-CCSD) quadratic and CI-like methods, in order to carry out quantitative NMR spin-spin coupling constant calculations for medium size molecules. In the calibration studies, we focus on the effects of the quadratic contribution, magnitude of the non Fermi-contact contributions, effects of the atomic basis set employed and electron correlation on NMR spin-spin coupling constant calculations with the EOM-CCSD quadratic and CI-like approximations. The results are found to be generally good, providing 13.9,8.4,7.3 and 7.6 mean absolute percent deviation from experiment, respectively, for DZP, TZP, Chipman and QZP basis sets. The overall mean absolute error of the EOM-CCSD results compared to experiment is 7%. The Fermi-contact contribution usually constitutes the largest portion of the total coupling constant. However, there are instances that the non-contact contributions are dominating, for example, HF and N{sub 2} molecules. Several interesting applications of the EOM-CCSD method have been reported.

Perera, A.J.; Bartlett, R.J. [Univ. of Florida, Gainesville, FL (United States)

1996-12-31

52

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

53

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

54

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

55

Dressed qubits in nuclear spin baths

We present a method to encode a dressed qubit into the product state of an electron spin localized in a quantum dot and its surrounding nuclear spins via a dressing transformation. In this scheme, the hyperfine coupling and a portion of a nuclear dipole-dipole interaction become logic gates, while they are the sources of decoherence in electron-spin qubit proposals. We discuss errors and corrections for the dressed qubits. Interestingly, the effective Hamiltonian of nuclear spins is equivalent to a pairing Hamiltonian, which provides the microscopic mechanism to protect dressed qubits against decoherence.

Wu Lianao [Department of Theoretical Physics and History of Science, Basque Country University (EHU/UPV), Post Office Box 644, ES-48080 Bilbao (Spain) and IKERBASQUE, Basque Foundation for Science, ES-48011 Bilbao (Spain)

2010-04-15

56

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

57

Room-temperature entanglement between single defect spins in diamond

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

58

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

59

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

60

Manipulating single electron spins and coherence in quantum dots

NASA Astrophysics Data System (ADS)

The non-destructive detection of a single electron spin in a quantum dot (QD) is demonstrated using a time- averaged magneto-optical Kerr rotation measurementootnotetextJ. Berezovsky, M. H. Mikkelsen, O. Gywat, N. G. Stoltz, L. A. Coldren, and D. D. Awschalom, Science 314, 1916 (2006).. This technique provides a means to directly probe the spin off- resonance, thus minimally disturbing the system. Furthermore, the ability to sequentially initialize, manipulate, and read out the state of a qubit, such as an electron spin in a quantum dot, is necessary for virtually any scheme for quantum information processing. In addition to the time-averaged measurements, we have extended the single dot KR technique into the time domain with pulsed pump and probe lasers, allowing the observation of the coherent evolution of an electron spin stateootnotetextM. H. Mikkelsen, J. Berezovsky, N. G. Stoltz, L. A. Coldren, and D. D. Awschalom, Nature Physics 3, 770 (2007).. The dot is formed by interface fluctuations of a GaAs quantum well and embedded in a diode structure to allow controllable gating/charging of the QD. To enhance the small single spin signal, the QD is positioned within a vertical optical cavity. Observations of coherent single spin precession in an applied magnetic field allow a direct measurement of the electron g-factor and transverse spin lifetime. These measurements reveal information about the relevant spin decoherence mechanisms, while also providing a sensitive probe of the local nuclear spin environment. Finally, we have recently eveloped a scheme for high speed all-optical manipulation of the spin state that enables multiple operations within the coherence timeootnotetextJ. Berezovsky, M. H. Mikkelsen, N. G. Stoltz, L. A. Coldren, and D. D. Awschalom, accepted for publication (2008).. The results represent progress toward the control and coupling of single spins and photons for quantum information processingootnotetextS. Ghosh, W.H. Wang, F. M. Mendoza, R. C. Myers, X. Li, N. Samarth, A. C. Gossard, and D. D. Awschalom, Nature Materials, 5, 267 (2006). as well as quantum non-demolition measurements of a single spin.

Awschalom, David

2008-05-01

61

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. PMID:25302916

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

2014-09-26

62

Single-proton spin detection by diamond magnetometry.

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

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

2014-10-16

63

Room temperature entanglement between distant single spins in diamond

Entanglement is the central yet fleeting phenomena of quantum physics. Once being considered a peculiar counter-intuitive property of quantum theory it has developed into the most central element of quantum technology providing speed up to quantum computers, a path towards long distance quantum cryptography and increased sensitivity in quantum metrology. Consequently, there have been a number of experimental demonstration of entanglement between photons, atoms, ions as well as solid state systems like spins or quantum dots, superconducting circuits and macroscopic diamond. Here we experimentally demonstrate entanglement between two engineered single solid state spin quantum bits (qubits) at ambient conditions. Photon emission of defect pairs reveals ground state spin correlation. Entanglement (fidelity = 0.67 \\pm 0.04) is proven by quantum state tomography. Moreover, the lifetime of electron spin entanglement is extended to ms by entanglement swapping to nuclear spins, demonstrating nuclear spin entanglement over a length scale of 25 nm. The experiments mark an important step towards a scalable room temperature quantum device being of potential use in quantum information processing as well as metrology.

Florian Dolde; Ingmar Jakobi; Boris Naydenov; Nan Zhao; Sebastien Pezzagna; Christina Trautmann; Jan Meijer; Philipp Neumann; Fedor Jelezko; Jörg Wrachtrup

2012-12-12

64

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

65

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

66

Optical Orientation of Nuclear Spins

Stray Field Images of nuclear polarization for 69 Ga as aStray Field Images of nuclear polarization for (a) 71 Gaimages for 69 Ga capture the changing shape of the distribution of nuclear polarization

King, Jonathan Patrick

2012-01-01

67

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

68

Nuclear moments of inertia at high spins

Nuclei with highest angular momentum are discussed. The production of high spin states, and the basic ideas associated with high spin physics are reviewed. Recent developments from continuum ..gamma..-ray studies are presented: the measurement of different average moments of inertia gives new information on the interplay between collective and single particle aspects at high spins. Finally, the exciting possibility of resolving the continuum spectra with new detector systems is examined. 8 references.

Deleplanque, M.A.

1983-12-01

69

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

70

The spin-temperature theory of dynamic nuclear polarization and nuclear spin-lattice relaxation

NASA Technical Reports Server (NTRS)

A detailed derivation of the equations governing dynamic nuclear polarization (DNP) and nuclear spin lattice relaxation by use of the spin temperature theory has been carried to second order in a perturbation expansion of the density matrix. Nuclear spin diffusion in the rapid diffusion limit and the effects of the coupling of the electron dipole-dipole reservoir (EDDR) with the nuclear spins are incorporated. The complete expression for the dynamic nuclear polarization has been derived and then examined in detail for the limit of well resolved solid effect transitions. Exactly at the solid effect transition peaks, the conventional solid-effect DNP results are obtained, but with EDDR effects on the nuclear relaxation and DNP leakage factor included. Explicit EDDR contributions to DNP are discussed, and a new DNP effect is predicted.

Byvik, C. E.; Wollan, D. S.

1974-01-01

71

EFFECTS OF NUCLEAR SPIN POLARIZATION ON REACTION DYNAMICS IN PHOTOSYNTHETIC

- cally induced dynamic nuclear polarization [CIDNP]) (Kaptein and Oosterhoff, 1969; Closs, 1969EFFECTS OF NUCLEAR SPIN POLARIZATION ON REACTION DYNAMICS IN PHOTOSYNTHETIC BACTERIAL REACTION-equilibrium distributions of nuclear spin states (nuclear spin polarization). This polarization will persist until the 3PI

Boxer, Steven G.

72

Long coherence of electron spins coupled to a nuclear spin bath

Qubits, the quantum mechanical bits required for quantum computing, must retain their fragile quantum states over long periods of time. In many types of electron spin qubits, the primary source of decoherence is the interaction between the electron spins and nuclear spins of the host lattice. For electrons in gate defined GaAs quantum dots, previous spin echo measurements have revealed coherence times of about 1 $\\mu$s at low magnetic fields below 100 mT. Here, we show that coherence in such devices can actually survive to much longer times, and provide a detailed understanding of the measured nuclear spin induced decoherence. At fields above a few hundred millitesla, the coherence time measured using a single-pulse spin echo extends to 30 $\\mu$s. At lower magnetic fields, the echo first collapses, but then revives at later times given by the period of the relative Larmor precession of different nuclear species. This behavior was recently predicted, and as we show can be quantitatively accounted for by a semi...

Bluhm, Hendrik; Neder, Izhar; Rudner, Mark; Mahalu, Diana; Umansky, Vladimir; Yacoby, Amir

2010-01-01

73

Dynamics of a mesoscopic nuclear spin ensemble interacting with an optically driven electron spin

NASA Astrophysics Data System (ADS)

The ability to discriminate between simultaneously occurring noise sources in the local environment of semiconductor InGaAs quantum dots, such as electric and magnetic field fluctuations, is key to understanding their respective dynamics and their effect on quantum dot coherence properties. We present a discriminatory approach to all-optical sensing based on two-color resonance fluorescence of a quantum dot charged with a single electron. Our measurements show that local magnetic field fluctuations due to nuclear spins in the absence of an external magnetic field are described by two correlation times, both in the microsecond regime. The nuclear spin bath dynamics show a strong dependence on the strength of resonant probing, with correlation times increasing by a factor of 4 as the optical transition is saturated. We interpret the behavior as motional averaging of both the Knight field of the resident electron spin and the hyperfine-mediated nuclear spin-spin interaction due to optically induced electron spin flips.

Stanley, M. J.; Matthiesen, C.; Hansom, J.; Le Gall, C.; Schulte, C. H. H.; Clarke, E.; Atatüre, M.

2014-11-01

74

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

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

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

2013-04-18

75

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

76

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

A single nuclear spin holds the promise of being a long-lived quantum bit or quantum memory, with the high fidelities required for fault-tolerant quantum computing. We show here that such promise could be fulfilled by a single phosphorus (31P) nuclear spin in a silicon nanostructure. By integrating single-shot readout of the electron spin with on-chip electron spin resonance, we demonstrate the quantum non-demolition, electrical single-shot readout of the nuclear spin, with readout fidelity better than 99.8% - the highest for any solid-state qubit. The single nuclear spin is then operated as a qubit by applying coherent radiofrequency (RF) pulses. For an ionized 31P donor we find a nuclear spin coherence time of 60 ms and a 1-qubit gate control fidelity exceeding 98%. These results demonstrate that the dominant technology of modern electronics can be adapted to host a complete electrical measurement and control platform for nuclear spin-based quantum information processing.

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

2013-02-01

77

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

78

Nuclear spin relaxation in polarized solid xenon

This thesis reports the results of a 3 year study of nuclear spin relaxation in solid [sup 129]Xe using highly polarized nuclei. The spin-1/2 nuclei of gaseous [sup 129]Xe atoms were polarized by spin-exchange with polarized Rb vapor, which was produced by continuous optical pumping of its principal resonance with a circularly polarized Ti:Sapphire laser. The Xe atoms were then frozen within the glass vapor cell by immersing it in liquid nitrogen. Relaxation of the nuclear polarization in the solid was observed by detecting the [sup 129]Xe nuclear magnetic resonance signal repeatedly over a period of time. The characteristic [sup 129]Xe relaxation time has been studied as a function of temperature from 4.2 K to near its boiling point at 161 K, and also as a function of applied magnetic field from near zero to about 2 kGauss. Measured relaxation times ranged from seconds to weeks; the longest time measured was 500 hours. From the results of this research, several different relaxation mechanisms for [sup 129]Xe have been identified. One is produced by internuclear magnetic dipole interactions which are modulated as a result of atomic self-diffusion within the high temperature Xe crystal. Another results from a nuclear spin-rotation interaction which produces a coupling between the nuclear spin-rotation and the thermal vibrations, or phonons, present in the crystal at all temperatures. At 4.2 K, [sup 129]Xe relaxes through a cross relaxation process with [sup 131]Xe, the spin-3/2 isotope of Xe. The relaxation time of [sup 131]Xe has been measured to be only minutes at 4.2 K because of its strong quadrupole coupling to electric field gradients in the crystal. Cross relaxation, which is simply spin-exchange between the two isotopes, therefore results in an effective relaxation mechanism for [sup 129]Xe. Cross relaxation has also been used to generate substantial [sup 131]Xe nuclear spin polarization.

Gatzke, M.A.

1992-01-01

79

Transverse single spin asymmetry measurements at STAR

NASA Astrophysics Data System (ADS)

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

Pan, Yuxi

2014-01-01

80

Optical pumping of a single hole spin in a quantum dot.

The spin of an electron is a natural two-level system for realizing a quantum bit in the solid state. For an electron trapped in a semiconductor quantum dot, strong quantum confinement highly suppresses the detrimental effect of phonon-related spin relaxation. However, this advantage is offset by the hyperfine interaction between the electron spin and the 10(4) to 10(6) spins of the host nuclei in the quantum dot. Random fluctuations in the nuclear spin ensemble lead to fast spin decoherence in about ten nanoseconds. Spin-echo techniques have been used to mitigate the hyperfine interaction, but completely cancelling the effect is more attractive. In principle, polarizing all the nuclear spins can achieve this but is very difficult to realize in practice. Exploring materials with zero-spin nuclei is another option, and carbon nanotubes, graphene quantum dots and silicon have been proposed. An alternative is to use a semiconductor hole. Unlike an electron, a valence hole in a quantum dot has an atomic p orbital which conveniently goes to zero at the location of all the nuclei, massively suppressing the interaction with the nuclear spins. Furthermore, in a quantum dot with strong strain and strong quantization, the heavy hole with spin-3/2 behaves as a spin-1/2 system and spin decoherence mechanisms are weak. We demonstrate here high fidelity (about 99 per cent) initialization of a single hole spin confined to a self-assembled quantum dot by optical pumping. Our scheme works even at zero magnetic field, demonstrating a negligible hole spin hyperfine interaction. We determine a hole spin relaxation time at low field of about one millisecond. These results suggest a route to the realization of solid-state quantum networks that can intra-convert the spin state with the polarization of a photon. PMID:18216849

Gerardot, Brian D; Brunner, Daniel; Dalgarno, Paul A; Ohberg, Patrik; Seidl, Stefan; Kroner, Martin; Karrai, Khaled; Stoltz, Nick G; Petroff, Pierre M; Warburton, Richard J

2008-01-24

81

Nuclear spin symmetry state relaxation in formaldehyde

NASA Astrophysics Data System (ADS)

New measurements of the rate constant of the ortho- para conversion in monomeric gaseous formaldehyde (H 2CO) are presented. Separation of the nuclear spin isomers of formaldehyde was obtained by selective UV laser photolysis of ortho-formaldehyde in the natural ortho- para mixture. A first group of experiments is devoted to the question of surface relaxation. Measurements in low pressure formaldehyde gas show fast relaxation at very low pressures, falling to a minimum at pressures of about 1 mbar and then rising linearly with pressure. The fast relaxation at very low pressures is interpreted as surface relaxation and this interpretation is confirmed by the fact that different wall materials of the fluorescence cells yield different relaxation constants. A second group of experiments extended the pressure range of the nuclear spin symmetry state relaxation measurements in formaldehyde by adding H 2 or SF 6 to it up to pressures of 1 bar. The experimental data follow qualitatively the behaviour that is predicted by theory [R.F. Curl Jr, J.V.V. Kasper, K.S. Pitzer, J. Chem. Phys. 46 (1967) 3220]. Quantitative agreement with theory could be reached by taking calculated values of the spin-rotation coupling constants [P.L. Chapovsky, J. Mol. Struct. 599 (2001) 337] about 35% higher and using surprisingly large nuclear spin symmetry state relaxation cross-sections.

Bechtel, Christian; Elias, Elias; Schramm, Bernhard F.

2005-05-01

82

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

83

Nuclear spin relaxation in Rashba nanowires

NASA Astrophysics Data System (ADS)

We study the nuclear spin relaxation in a ballistic nanowire with hyperfine and Rashba spin-orbit interactions (SOI) and in the presence of magnetic field and electron interactions. The relaxation rate shows pronounced peaks as a function of magnetic field and chemical potential due to van Hove singularities in the Rashba bands. As a result, the regimes of weak and strong SOIs can be distinguished by the number of peaks in the rate. The relaxation rate increases with increasing magnetic field if both Rashba subbands are occupied, whereas it decreases if only the lowest one is occupied.

Zyuzin, Alexander A.; Meng, Tobias; Kornich, Viktoriia; Loss, Daniel

2014-11-01

84

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

85

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

86

Coherent single-spin source based on topological insulators

NASA Astrophysics Data System (ADS)

We report on the injection of quantized pure spin current into quantum conductors. In particular, we propose an on-demand single-spin source generated by periodically varying the gate voltages of two quantum dots that are connected to a two-dimensional topological insulator via tunneling barriers. Due to the nature of the helical states of the topological insulator, one or several spin pairs can be pumped out per cycle giving rise to a pure quantized alternating spin current. Depending on the phase difference between two gate voltages, this device can serve as an on-demand single-spin emitter or single-charge emitter. Again, due to the helicity of the topological insulator, the single-spin emitter or charge emitter is dissipationless and immune to disorder. The proposed single-spin emitter can be an important building block of future spintronic devices.

Xing, Yanxia; Yang, Zhong-liu; Sun, Qing-feng; Wang, Jian

2014-08-01

87

Atomic-Scale Nuclear Spin Imaging Using Quantum-Assisted Sensors in Diamond

NASA Astrophysics Data System (ADS)

Nuclear spin imaging at the atomic level is essential for the understanding of fundamental biological phenomena and for applications such as drug discovery. The advent of novel nanoscale sensors promises to achieve the long-standing goal of single-protein, high spatial-resolution structure determination under ambient conditions. In particular, quantum sensors based on the spin-dependent photoluminescence of nitrogen-vacancy (NV) centers in diamond have recently been used to detect nanoscale ensembles of external nuclear spins. While NV sensitivity is approaching single-spin levels, extracting relevant information from a very complex structure is a further challenge since it requires not only the ability to sense the magnetic field of an isolated nuclear spin but also to achieve atomic-scale spatial resolution. Here, we propose a method that, by exploiting the coupling of the NV center to an intrinsic quantum memory associated with the nitrogen nuclear spin, can reach a tenfold improvement in spatial resolution, down to atomic scales. The spatial resolution enhancement is achieved through coherent control of the sensor spin, which creates a dynamic frequency filter selecting only a few nuclear spins at a time. We propose and analyze a protocol that would allow not only sensing individual spins in a complex biomolecule, but also unraveling couplings among them, thus elucidating local characteristics of the molecule structure.

Ajoy, A.; Bissbort, U.; Lukin, M. D.; Walsworth, R. L.; Cappellaro, P.

2015-01-01

88

Atomic-scale nuclear spin imaging using quantum-assisted sensors in diamond

Nuclear spin imaging at the atomic level is essential for the understanding of fundamental biological phenomena and for applications such as drug discovery. The advent of novel nano-scale sensors has given hope of achieving the long-standing goal of single-protein, high spatial-resolution structure determination in their natural environment and ambient conditions. In particular, quantum sensors based on the spin-dependent photoluminescence of Nitrogen Vacancy (NV) centers in diamond have recently been used to detect nanoscale ensembles of external nuclear spins. While NV sensitivity is approaching single-spin levels, extracting relevant information from a very complex structure is a further challenge, since it requires not only the ability to sense the magnetic field of an isolated nuclear spin, but also to achieve atomic-scale spatial resolution. Here we propose a method that, by exploiting the coupling of the NV center to an intrinsic quantum memory associated with the Nitrogen nuclear spin, can reach a tenfold improvement in spatial resolution, down to atomic scales. The spatial resolution enhancement is achieved through coherent control of the sensor spin, which creates a dynamic frequency filter selecting only a few nuclear spins at a time. We propose and analyze a protocol that would allow not only sensing individual spins in a complex biomolecule, but also unraveling couplings among them, thus elucidating local characteristics of the molecule structure.

Ashok Ajoy; Ulf Bissbort; Mikhail D. Lukin; Ronald L. Walsworth; Paola Cappellaro

2014-07-11

89

Nuclear spin symmetry state relaxation in formaldehyde

New measurements of the rate constant of the ortho–para conversion in monomeric gaseous formaldehyde (H2CO) are presented. Separation of the nuclear spin isomers of formaldehyde was obtained by selective UV laser photolysis of ortho-formaldehyde in the natural ortho–para mixture. A first group of experiments is devoted to the question of surface relaxation. Measurements in low pressure formaldehyde gas show fast

Christian Bechtel; Elias Elias; Bernhard F. Schramm

2005-01-01

90

Recursive polarization of nuclear spins in diamond at arbitrary magnetic fields

NASA Astrophysics Data System (ADS)

We introduce an alternate route to dynamically polarize the nuclear spin host of nitrogen-vacancy (NV) centers in diamond. Our approach articulates optical, microwave, and radio-frequency pulses to recursively transfer spin polarization from the NV electronic spin. Using two complementary variants of the same underlying principle, we demonstrate nitrogen nuclear spin initialization approaching 80% at room temperature both in ensemble and single NV centers. Unlike existing schemes, our approach does not rely on level anti-crossings and is thus applicable at arbitrary magnetic fields. This versatility should prove useful in applications ranging from nanoscale metrology to sensitivity-enhanced NMR.

Pagliero, Daniela; Laraoui, Abdelghani; Henshaw, Jacob D.; Meriles, Carlos A.

2014-12-01

91

Coherent control of a single electron spin with electric fields.

Manipulation of single spins is essential for spin-based quantum information processing. Electrical control instead of magnetic control is particularly appealing for this purpose, because electric fields are easy to generate locally on-chip. We experimentally realized coherent control of a single-electron spin in a quantum dot using an oscillating electric field generated by a local gate. The electric field induced coherent transitions (Rabi oscillations) between spin-up and spin-down with 90 degrees rotations as fast as approximately 55 nanoseconds. Our analysis indicated that the electrically induced spin transitions were mediated by the spin-orbit interaction. Taken together with the recently demonstrated coherent exchange of two neighboring spins, our results establish the feasibility of fully electrical manipulation of spin qubits. PMID:17975030

Nowack, K C; Koppens, F H L; Nazarov, Yu V; Vandersypen, L M K

2007-11-30

92

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

93

Nuclear Spins as Quantum Memory in Semiconductor Nanostructures

We theoretically consider solid state nuclear spins in a semiconductor nanostructure environment as long-lived, high-fidelity quantum memory. In particular, we calculate, in the limit of a strong applied magnetic field, the fidelity versus time of P donor nuclear spins in random bath environments of Si and GaAs, and the lifetime of excited intrinsic spins in polarized Si and GaAs environments. In the former situation, the nuclear spin dephases due to spectral diffusion induced by the dipolar interaction among nuclei in the bath. We calculate the decay of nuclear spin quantum memory in the context of Hahn and Carr-Purcell-Meiboom-Gill (CPMG) refocused spin echoes using a formally exact cluster expansion technique which has previously been successful in dealing with electron spin dephasing in a solid state nuclear spin bath. With decoherence dominated by transverse dephasing (T2), we find it feasible to maintain high fidelity (losses of less than 10^{-6}) quantum memory on nuclear spins for times of the order of 100 microseconds (GaAs:P) and 1 to 2 milliseconds (natural Si:P) using CPMG pulse sequences of just a few (~2-4) applied pulses. We also consider the complementary situation of a central flipped intrinsic nuclear spin in a bath of completely polarized nuclear spins where decoherence is caused by the direct flip-flop of the central spin with spins in the bath. Exact numerical calculations that include a sufficiently large neighborhood of surrounding nuclei show lifetimes on the order of 1-5 ms for both GaAs and natural Si. Our calculated nuclear spin coherence times may have significance for solid state quantum computer architectures using localized electron spins in semiconductors where nuclear spins have been proposed for quantum memory storage.

W. M. Witzel; S. Das Sarma

2007-01-19

94

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

Rabi oscillations and adiabatic passage of single electron spins in a diamond nitrogen vacancy center are demonstrated with two Raman-resonant optical pulses that are detuned from the respective dipole optical transitions. We show that the optical spin control is nuclear-spin selective and can be robust against rapid decoherence, including radiative decay and spectral diffusion, of the underlying optical transitions. A direct comparison between the Rabi oscillation and the adiabatic passage, along with a detailed theoretical analysis, provides significant physical insights into the connections and differences between these coherent spin processes and also elucidates the role of spectral diffusion in these processes. The optically driven coherent spin processes enable the use of nitrogen vacancy excited states to mediate coherent spin-phonon coupling, opening the door to combining optical control of both spin and mechanical degrees of freedom. PMID:24702393

Golter, D Andrew; Wang, Hailin

2014-03-21

95

Single Spin Asymmetry in Charmonium Production

NASA Astrophysics Data System (ADS)

We present estimates of single spin asymmetry (SSA) in the electroproduction of {J/?} 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 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.; Kaushik, Abhiram; Misra, Anuradha; Rawoot, Vaibhav

2015-01-01

96

Technical Notes Single-Sensor Identification of Spinning

Technical Notes Single-Sensor Identification of Spinning Mode Noise from Aircraft Engine Xun Huang function of the first kind K = gain of Kalman filter k = spinning mode frequency, Hz ka = axial wave number, rad = flow density, kg=m3 Subscripts Am = mth spinning mode of A A0 = mean value of A Superscripts ^A

Huang, Xun

97

Qubit Protection in Nuclear-Spin Quantum Dot Memories

We present a mechanism to protect quantum information stored in an ensemble of nuclear spins in a semiconductor quantum dot. When the dot is charged the nuclei interact with the spin of the excess electron through the ...

Taylor, J. M.

98

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

2010-09-09

99

Observation of spin-light coherence for single spin measurement and control in diamond

NASA Astrophysics Data System (ADS)

The long spin coherence and optical addressability of nitrogen-vacancy (NV) centers in diamond makes them excellent candidates for studies of quantum information science with potential technological applications. We demonstrate the coherent coupling of light to the electronic spin of a single NV center for both non-destructive, single-spin readout via the Faraday effect and unitary, single-spin control via the optical Stark effectootnotetextB. B. Buckley, G. D. Fuchs, L. C. Bassett, D. D. Awschalom, Science Express (DOI: 10.1126/science.1196436). By monitoring the Faraday effect of laser light focused on a single NV center and detuned from optical resonances, we are able to read out an NV center's spin state without destroying it, in contrast to traditional spin readout techniques which polarize the spin during measurement. In a complimentary way, the spin coherently rotates in response to the light through the optical Stark effect, which we demonstrate as a method of all-optical spin control. These measurements have important consequences for future single-spin quantum non-demolition measurements and spin-photon entanglement schemes in diamond that may be exploited for the development of quantum repeater technologies and photonic coupling of spins over large distances.

Buckley, Bob

2011-03-01

100

Detection and manipulation of nuclear spin states in fermionic strontium

Fermionic {sup 87}Sr has a nuclear spin of I=9/2, higher than any other element with a similar electronic structure. This large nuclear spin has many applications in quantum simulation and computation, for which preparation and detection of the spin state are requirements. For an ultracold {sup 87}Sr cloud, we show two complementary methods to characterize the spin-state mixture: optical Stern-Gerlach state separation and state-selective absorption imaging. We use these methods to optimize the preparation of a variety of spin-state mixtures by optical pumping and to measure an upper bound of the {sup 87}Sr spin-relaxation rate.

Stellmer, Simon; Grimm, Rudolf [Institut fuer Quantenoptik und Quanteninformation (IQOQI), Oesterreichische Akademie der Wissenschaften, A-6020 Innsbruck (Austria); Institut fuer Experimentalphysik und Zentrum fuer Quantenphysik, Universitaet Innsbruck, A-6020 Innsbruck (Austria); Schreck, Florian [Institut fuer Quantenoptik und Quanteninformation (IQOQI), Oesterreichische Akademie der Wissenschaften, A-6020 Innsbruck (Austria)

2011-10-15

101

Nuclear magnetometry studies of spin dynamics in quantum Hall systems

NASA Astrophysics Data System (ADS)

We performed a nuclear magnetometry study on quantum Hall ferromagnet with a bilayer total filling factor of ?tot=2 . We found not only a rapid nuclear relaxation but also a sudden change in the nuclear-spin polarization distribution after a one-second interaction with a canted antiferromagnetic phase. We discuss the possibility of observing cooperative phenomena coming from nuclear-spin ensemble triggered by hyperfine interaction in quantum Hall system.

Fauzi, M. H.; Watanabe, S.; Hirayama, Y.

2014-12-01

102

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

103

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

104

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

2006-01-09

105

Interaction of acoustic waves with nuclear spins in solids

A review of the interactions of high-frequency acoustic waves with nuclear spins in solids is presented here. These interactions result from the modulation of internal magnetic fields and electric field gradients by the impressed acoustic wave. The acoustic technique is especially useful in investigating the coupling of nuclear spins to the lattice vibrations (phonons) of the solid, and in many

D. I. Bolef; R. K. Sundfors

1965-01-01

106

Self-quenching of nuclear spin dynamics in the central spin problem

NASA Astrophysics Data System (ADS)

We consider, in the framework of the central spin s =1/2 model, driven dynamics of two electrons in a double quantum dot subject to hyperfine interaction with nuclear spins and spin-orbit coupling. The nuclear subsystem dynamically evolves in response to Landau-Zener singlet-triplet transitions of the electronic subsystem controlled by external gate voltages. Without noise and spin-orbit coupling, subsequent Landau-Zener transitions die out after about 104 sweeps, the system self-quenches, and nuclear spins reach one of the numerous glassy dark states. We present an analytical model that captures this phenomenon. We also account for the multi-nuclear-specie content of the dots and numerically determine the evolution of around 107 nuclear spins in up to 2×105 Landau-Zener transitions. Without spin-orbit coupling, self-quenching is robust and sets in for arbitrary ratios of the nuclear spin precession times and the waiting time between Landau-Zener sweeps as well as under moderate noise. In the presence of spin-orbit coupling of a moderate magnitude, and when the waiting time is in resonance with the precession time of one of the nuclear species, the dynamical evolution of nuclear polarization results in stroboscopic screening of spin-orbit coupling. However, small deviations from the resonance or strong spin-orbit coupling destroy this screening. We suggest that the success of the feedback loop technique for building nuclear gradients is based on the effect of spin-orbit coupling.

Brataas, Arne; Rashba, Emmanuel I.

2014-01-01

107

Nanoscale magnetometry using a single spin system in diamond

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

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

2011-03-24

108

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

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

Ramos, J. P.; Apel, V. M. [Departamento de Física, Universidad Católica del Norte, Angamos 0610, Casilla 1280, Antofagasta (Chile); Foa Torres, L. E. F. [Instituto de Física Enrique Gaviola (CONICET) and FaMAF, Universidad Nacional de Córdoba, Ciudad Universitaria 5000, Córdoba (Argentina); Orellana, P. A. [Departamento de Física, Universidad Técnica Federico Santa María, Avenida Vicuña Mackenna 3939, San Joaquin, Santiago (Chile)

2014-03-28

109

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

110

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

111

Transverse Single-Spin Asymmetries: Challenges and Recent Progress

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

112

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

113

The silicon-vacancy (SiV^{-}) color center in diamond has attracted attention because of its unique optical properties. It exhibits spectral stability and indistinguishability that facilitate efficient generation of photons capable of demonstrating quantum interference. Here we show optical initialization and readout of electronic spin in a single SiV^{-} center with a spin relaxation time of T_{1}=2.4±0.2??ms. Coherent population trapping (CPT) is used to demonstrate coherent preparation of dark superposition states with a spin coherence time of T_{2}^{?}=35±3??ns. This is fundamentally limited by orbital relaxation, and an understanding of this process opens the way to extend coherence by engineering interactions with phonons. Hyperfine structure is observed in CPT measurements with the ^{29}Si isotope which allows access to nuclear spin. These results establish the SiV^{-} center as a solid-state spin-photon interface. PMID:25615330

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

2014-12-31

114

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

115

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

116

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 1H 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 1H 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 mm3) containing >1019 1H 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

2014-01-01

117

Manipulating Single Spins in Quantum Dots Coupled to Ferromagnetic Leads

NASA Astrophysics Data System (ADS)

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

König, Jürgen; Braun, Matthias; Martinek, Jan

118

Solid-State Nuclear Spin Quantum Computer Based on Magnetic Resonance Force Microscopy

We propose a nuclear spin quantum computer based on magnetic resonance force microscopy (MRFM). It is shown that an MRFM single-electron spin measurement provides three essential requirements for quantum computation in solids: (a) preparation of the ground state, (b) one- and two- qubit quantum logic gates, and (c) a measurement of the final state. The proposed quantum computer can operate at temperatures up to 1K.

G. P. Berman; G. D. Doolen; P. C. Hammel; V. I. Tsifrinovich

1999-09-09

119

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

120

Single-spin asymmetries: The Trento conventions

During the workshop 'Transversity: New Developments in Nucleon Spin Structure' (ECT, Trento, Italy, 14-18 June 2004), a series of recommendations was put forward by the participants concerning definitions and notations for describing effects of intrinsic transverse-momentum of partons in semi-inclusive deep inelastic scattering.

Bacchetta, Alessandro; D'Alesio, Umberto; Diehl, Markus; Miller, C. Andy [Institut fuer Theoretische Physik, Universitaet Regensburg, D-93040 Regensburg (Germany); INFN, Sezione di Cagliari and Dipartimento di Fisica, Universita di Cagliari, I-09042 Monserrato (Italy); Deutsches Elektronen-Synchroton DESY, D-22603 Hamburg (Germany); TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada)

2004-12-01

121

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

122

Reviews of Topical Problems: Nuclear Spin Resonance

I. Introduction 566 II. NSR energy levels and frequencies 568 1. Energy levels for resonating nuclei with spins 1 or 3\\/2 568 2. NSR energy levels for spin 5\\/2 571 III. Relative intensities of NSR lines 571 1. Relative intensities of Zeeman components in NQR 571 2. Generalized NSR equations 572 3. Relative intensities of NSR lines for spin 1

Vadim S. Grechishkin; N. E. Ainbinder

1964-01-01

123

Engineering Nuclear spin has now been associated with Nobel Prizes

Chemical Engineering Nuclear spin has now been associated with Nobel Prizes in Physics, Chemistry-2003, Professor Reimer won the Donald Sterling Noyce Prize, the AIChE Northern California Section Award and the UC

124

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

NASA Astrophysics Data System (ADS)

Quantum dot quantum computing architectures rely on systems in which inversion symmetry is broken, and spin-orbit coupling is present, causing even single-spin qubits to be susceptible to charge noise. We derive an effective Hamiltonian for the combined action of noise and spin-orbit coupling on a single-spin qubit, identify the mechanisms behind dephasing, and estimate the free induction decay dephasing times T2* for common materials such as Si and GaAs. Dephasing is driven by noise matrix elements that cause relative fluctuations between orbital levels, which are dominated by screened whole charge defects and unscreened dipole defects in the substrate. Dephasing times T2* differ markedly between materials and can be enhanced by increasing gate fields, choosing materials with weak spin-orbit, making dots narrower, or using accumulation dots.

Bermeister, Adam; Keith, Daniel; Culcer, Dimitrie

2014-11-01

125

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

126

On the electron scattering and dephasing by the nuclear spins

We show that scattering of the conduction electrons by nuclear spins via the\\u000ahyperfine interaction may lead the upper limit on the mean free path in clean\\u000ametals. Nuclear spins with s >1\\/2 may cause a strong dephasing in dirty limit\\u000adue to the quadrupole coupling to the random potential fluctuations caused by\\u000astatic impurities and lattice imperfections.

A. M. Dyugaev; I. D. Vagner; P. Wyder

2000-01-01

127

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

128

Excited-state spectroscopy using single spin manipulation in diamond.

We use single-spin resonant spectroscopy to study the spin structure in the orbital excited state of a diamond nitrogen-vacancy (N-V) center at room temperature. The data show that the excited-state spin levels have a zero-field splitting that is approximately half of the value of the ground state levels, a g factor similar to the ground state value, and a hyperfine splitting approximately 20x larger than in the ground state. In addition, the width of the resonances reflects the electronic lifetime in the excited state. We also show that the spin level splitting can significantly differ between N-V centers, likely due to the effects of local strain, which provides a pathway to control over the spin Hamiltonian and may be useful for quantum-information processing. PMID:18851332

Fuchs, G D; Dobrovitski, V V; Hanson, R; Batra, A; Weis, C D; Schenkel, T; Awschalom, D D

2008-09-12

129

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

130

Quantum simulation of spin ordering with nuclear spins in a solid state lattice

An experiment demonstrating the quantum simulation of a spin-lattice Hamiltonian is proposed. Dipolar interactions between nuclear spins in a solid state lattice can be modulated by rapid radio-frequency pulses. In this way, the effective Hamiltonian of the system can be brought to the form of an antiferromagnetic Heisenberg model with long range interactions. Using a semiconducting material with strong optical properties such as InP, cooling of nuclear spins could be achieved by means of optical pumping. An additional cooling stage is provided by adiabatic demagnetization in the rotating frame (ADRF) down to a nuclear spin temperature at which we expect a phase transition from a paramagnetic to antiferromagnetic phase. This phase transition could be observed by probing the magnetic susceptibility of the spin-lattice. Our calculations suggest that employing current optical pumping technology, observation of this phase transition is within experimental reach.

Georgios Roumpos; Cyrus P. Master; Yoshihisa Yamamoto

2006-11-21

131

Interaction of Acoustic Phonons with Nuclear Spins in KTaO3

The nuclear spin resonance of 181Ta in a single crystal of KTaO3 has been studied using the technique of direct ultrasonic excitation. Nuclear resonances have been observed for transitions where Deltam=+\\/-1 and +\\/-2, where m is the magnetic quantum number. Longitudinal and both polarizations of transverse waves, set up along the [100] axis of the cubic crystal, were used to

E. H. Gregory

1968-01-01

132

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

133

A single-atom electron spin qubit in silicon.

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

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

2012-09-27

134

Spin-transfer torque in a single ferromagnet

NASA Astrophysics Data System (ADS)

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

Ji, Yi

2004-03-01

135

Single-spin observables and orbital structures in hadronic distributions

NASA Astrophysics Data System (ADS)

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

Sivers, Dennis

2006-11-01

136

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

137

Nuclear-spin observation of noise spectra in semiconductors

We propose a systematic method of obtaining the spectra of noises that cause the decoherence of spins in solids. Based on this method, we experimentally show that this method can be applied to nuclear spins in semiconductors. We clarify that the spectral intensity must be derived from the long-time tail of the multiple-echo decay. To obtain higher-frequency noise, the inversion-pulse interval must be as short as possible, which required us to employ the alternating-phase Carr-Purcell sequence instead of the widely used Carr-Purcell Meiboom-Gill. For {sup 75}As nuclear spin in variously-doped GaAs, we observed a Lorentzian spectrum, instead of the commonly observed 1/f spectrum. This indicates that the nuclear spins are indeed in a coherently-controlled state.

Sasaki, Susumu; Nishimori, Masashi; Kawanago, Takashi [Department of Materials Science, Niigata University, Niigata 950-2181 (Japan); Yuge, Tatsuro [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan); Hirayama, Yoshiro [Department of Physics, Tohoku University, Sendai 980-8578, Japan and JST-ERATO Nuclear Spin Electronics Project, Sendai 980-8578 (Japan)

2013-12-04

138

Nuclear-spin observation of noise spectra in semiconductors

NASA Astrophysics Data System (ADS)

We propose a systematic method of obtaining the spectra of noises that cause the decoherence of spins in solids. Based on this method, we experimentally show that this method can be applied to nuclear spins in semiconductors. We clarify that the spectral intensity must be derived from the long-time tail of the multiple-echo decay. To obtain higher-frequency noise, the inversion-pulse interval must be as short as possible, which required us to employ the alternating-phase Carr-Purcell sequence instead of the widely used Carr-Purcell Meiboom-Gill. For 75As nuclear spin in variously-doped GaAs, we observed a Lorentzian spectrum, instead of the commonly observed 1/f spectrum. This indicates that the nuclear spins are indeed in a coherently-controlled state.

Sasaki, Susumu; Yuge, Tatsuro; Nishimori, Masashi; Kawanago, Takashi; Hirayama, Yoshiro

2013-12-01

139

Spin density matrices for nuclear density functionals with parity violations

The spin density matrix (SDM) used in atomic and molecular physics is revisited for nuclear physics, in the context of the radial density functional theory. The vector part of the SDM defines a "hedgehog" situation, which exists only if nuclear states contain some amount of parity violation.

B. R. Barrett; B. G. Giraud

2010-04-26

140

Spin squeezing of a cold atomic ensemble with the nuclear spin of one-half

To establish an applicable system for advanced quantum information processing between light and atoms, we have demonstrated the quantum non-demolition (QND) measurement with a collective spin of cold ytterbium atoms (171Yb), and observed 1.8 (-1.5, +2.4) dB spin squeezing. Since a 171Yb atom has only a nuclear spin of 1/2 in the ground state, the system is the simplest spin ensemble and robust against decoherence. We used very short pulses with the width of 100 ns, so the interaction time became much shorter than the decoherence time, which is important for multi-step quantum information processing.

Takano, T; Namiki, R; Takahashi, Y

2008-01-01

141

Spin squeezing of a cold atomic ensemble with the nuclear spin of one-half

To establish an applicable system for advanced quantum information processing between light and atoms, we have demonstrated the quantum non-demolition (QND) measurement with a collective spin of cold ytterbium atoms (171Yb), and observed 1.8 (-1.5, +2.4) dB spin squeezing. Since a 171Yb atom has only a nuclear spin of 1/2 in the ground state, the system is the simplest spin ensemble and robust against decoherence. We used very short pulses with the width of 100 ns, so the interaction time became much shorter than the decoherence time, which is important for multi-step quantum information processing.

T. Takano; M. Fuyama; R. Namiki; Y. Takahashi

2008-08-18

142

Coherent mechanical control of a single electronic spin

NASA Astrophysics Data System (ADS)

Quantum control of spins via electrical, magnetic, and optical means has generated numerous applications in metrology and quantum information technology. In this talk we present an alternative control scheme that uses the mechanical motion of a resonator to coherently control spins. Specifically, by coupling the motion of a magnetically coated mechanical oscillator to a single nitrogen-vacancy (NV) defect in diamond, we demonstrate manipulations of both the amplitude and phase of the NV's electronic spin. Coherent control is achieved by synchronizing NV-addressing optical and microwave manipulations to the driven motion of the coupled mechanical oscillator, which additionally allows for a stroboscopic readout of the resonator's motion. We demonstrate applications of this mechanical spin control to sensitive nanoscale scanning magnetometry and discuss the potential for sensitive motion sensing of nanomechanical resonators.

Grinolds, Michael

2013-03-01

143

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

Raghunathan, Shesha; Brun, Todd A. [Center for Quantum Information Science and Technology, Communication Sciences Institute, Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089 (United States); Goan, Hsi-Sheng [Department of Physics and Center for Theoretical Sciences, National Taiwan University, Taipei 10617, Taiwan (China); Center for Quantum Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

2010-11-15

144

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

145

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

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 (199)Hg and (13)C upon coordination of dimethylsulfoxide solvent molecules. PMID:24628152

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

2014-03-14

146

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

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 {sup 199}Hg and {sup 13}C upon coordination of dimethylsulfoxide solvent molecules.

Götz, Andreas W., E-mail: agoetz@sdsc.edu [San Diego Supercomputer Center, University of California San Diego, 9500 Gilman Dr MC 0505, La Jolla, California 92093-0505 (United States); Autschbach, Jochen [Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000 (United States)] [Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000 (United States); Visscher, Lucas, E-mail: visscher@chem.vu.nl [Amsterdam Center for Multiscale Modeling (ACMM), VU University Amsterdam, Theoretical Chemistry, De Boelelaan 1083, 1081 HV Amsterdam (Netherlands)] [Amsterdam Center for Multiscale Modeling (ACMM), VU University Amsterdam, Theoretical Chemistry, De Boelelaan 1083, 1081 HV Amsterdam (Netherlands)

2014-03-14

147

Nuclear-spin dependent parity violation in diatomic molecular ions

Nuclear-spin-dependent (NSD) parity violating (PV) effects can be strongly enhanced in diatomic molecules containing heavy atoms. Future measurements are anticipated to provide nuclear anapole moments and strength constants for PV nuclear forces. In light molecules, the NSD electroweak electron-nucleus interaction may also be detected. Here we calculate NSD PV effects for molecular ions. Our calculations are motivated by rapid developments in trapping techniques for such systems at low temperatures.

Borschevsky, A; Dzuba, V A; Beloy, K; Flambaum, V V; Schwerdtfeger, P A

2012-01-01

148

Quantum Non-demolition measurements of single spins in semiconductors

NASA Astrophysics Data System (ADS)

For the development of large-scale quantum computers, electron spin-encoded qubits in solid-state are appealing because of their favorable decoherence time scales, high potential for scalability, and many handles for precision control. However, an additional requirement that is traditionally challenging in the solid-state is a capacity for high-fidelity qubit readout. We propose a scheme for measuring the state of a single donor electron spin using a field-effect transistor induced two-dimensional electron gas and electrically detected magnetic resonance techniques. The scheme is facilitated by hyperfine coupling to the donor nucleus. We analyze the potential sensitivity and outline experimental requirements. Our measurement provides a single-shot, projective, and effectively quantum non-demolition measurement of an electron spin-encoded qubit state.

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

2008-03-01

149

Using nanoscale transistors to measure single donor spins in semiconductors

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

150

Spin models for the single molecular magnet Mn12-AC

NASA Astrophysics Data System (ADS)

The single molecular magnet (SMM) Mn12-AC attracted the attention of scientists since the discovery of its magnetic hystereses which are accompanied by sudden jumps in magnetic moments at low temperature. Unlike conventional bulk magnets, hysteresis in SMMs is of molecular origin. This qualifies them as candidates for next generation of high density storage media where a molecule which is at most few nanometers in size can be used to store a bit of information. However, the jumps in these hystereses, due to spin tunneling, can lead to undesired loss of information. Mn12-AC molecule contains twelve magnetic ions antiferromagnetically coupled by exchanges leading to S = 10 ground state manifold. The magnetic ions are surrounded by ligands which isolate them magnetically from neighboring molecules. The lowest state of S = 9 manifold is believed to lie at about 40 K above the ground state. Therefore, at low temperatures, the molecule is considered as a single uncoupled moment of spin S = 10. Such model has been used widely to understand phenomena exhibited by the molecule at low temperatures including the tunneling of its spin, while a little attention has been paid for the multi-spin nature of the molecule. Using the 8-spin model, we demonstrate that in order to understand the phenomena of tunneling, a full spin description of the molecule is required. We utilized a calculation scheme where a fraction of energy levels are used in the calculations and the influence of levels having higher energy is neglected. From the dependence of tunnel splittings on the number of states include, we conclude that models based on restricting the number of energy levels (single-spin and 8-spin models) lead to unreliable results of tunnel splitting calculations. To attack the full 12-spin model, we employed the Davidson algorithm to calculated lowest energy levels produced by exchange interactions and single ion anisotropies. The model reproduces the anisotropy properties at low temperature very well. At higher energy levels, however, the agreement is qualitative. Toward better quantitative agreement, further terms must be included in the Hamiltonian and further developments of computation algorithms are needed to overcome the size of the problem.

Al-Saqer, Mohamad A.

2005-11-01

151

Nonlinear single-spin spectrum analyzer.

Qubits have been used as linear spectrum analyzers of their environments. Here we solve the problem of nonlinear spectral analysis, required for discrete noise induced by a strongly coupled environment. Our nonperturbative analytical model shows a nonlinear signal dependence on noise power, resulting in a spectral resolution beyond the Fourier limit as well as frequency mixing. We develop a noise characterization scheme adapted to this nonlinearity. We then apply it using a single trapped ion as a sensitive probe of strong, non-Gaussian, discrete magnetic field noise. Finally, we experimentally compared the performance of equidistant vs Uhrig modulation schemes for spectral analysis. PMID:25166519

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

2013-03-15

152

Nonlinear Single-Spin Spectrum Analyzer

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

153

Spin constraints on nuclear energy density functionals

NASA Astrophysics Data System (ADS)

The Gallagher-Moszkowski rule in the spectroscopy of odd-odd nuclei imposes a new spin constraint on the energy functionals for self-consistent mean field theory. The commonly used parametrization of the effective three-body interaction in the Gogny and Skyrme families of energy functionals is ill suited to satisfy the spin constraint. In particular, the Gogny parametrization of the three-body interaction has the spin dependence opposite to that required by the observed spectra. The two-body part has a correct sign, but in combination the rule is violated as often as not. We conclude that a new functional form is needed for the effective three-body interaction that can take into better account the different spin-isospin channels of the interaction.

Robledo, L. M.; Bernard, R. N.; Bertsch, G. F.

2014-02-01

154

The Nuclear Cusp Condition in Spin-Polarized Thomas - Theory.

NASA Astrophysics Data System (ADS)

Thomas-Fermi theory, which was introduced in the 1920s, was developed into rigorous mathematics in the 1970s by Lieb, Simon, Benilan, Brezis, and others. Later, Goldstein and Rieder extended rigorous Thomas-Fermi theory to a spin polarized context, to include the nuclear cusp condition, and to the case where a magnetic field is present. But they did not investigate incorporating the nuclear cusp condition into the spin polarized context. The purpose of my thesis is to do precisely that. I proved the existence and uniqueness of the problem of minimizing the energy functional by solving a non-linear elliptic partial differential equation on { bf R}^3 which arose from the Euler -Lagrange equation. A topological argument then related the Lagrange multipliers to the numbers of spin up and spin down electrons.

Lung, Chien-An.

155

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

156

High precision quantum control of single donor spins in silicon

The Stark shift of the hyperfine coupling constant is investigated for a P donor in Si far below the ionization regime in the presence of interfaces using Tight-binding and Band Minima Basis approaches and compared to the recent precision measurements. The TB electronic structure calculations included over 3 million atoms. In contrast to previous effective mass based results, the quadratic Stark coefficient obtained from both theories agrees closely with the experiments. This work represents the most sensitive and precise comparison between theory and experiment for single donor spin control. It is also shown that there is a significant linear Stark effect for an impurity near the interface, whereas, far from the interface, the quadratic Stark effect dominates. Such precise control of single donor spin states is required particularly in quantum computing applications of single donor electronics, which forms the driving motivation of this work.

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

2007-05-15

157

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

158

Local manipulation of nuclear spin in a semiconductor quantum well.

The shaping of nuclear spin polarization profiles and the induction of nuclear resonances are demonstrated within a parabolic quantum well using an externally applied gate voltage. Voltage control of the electron and hole wave functions results in nanometer-scale sheets of polarized nuclei positioned along the growth direction of the well. Applying rf voltages across the gates induces resonant spin transitions of selected isotopes. This depolarizing effect depends strongly on the separation of electrons and holes, suggesting that a highly localized mechanism accounts for the observed behavior. PMID:14683395

Poggio, M; Steeves, G M; Myers, R C; Kato, Y; Gossard, A C; Awschalom, D D

2003-11-14

159

NASA Astrophysics Data System (ADS)

We demonstrated electrical spin injection from a half-metallic Heusler alloy Co2MnSi electrode into a GaAs channel through observation of a spin-valve signal and a Hanle signal in the four-terminal nonlocal geometry. Furthermore, we electrically detected a nuclear field acting on electron spins, which was produced by the dynamic nuclear polarization, through observation of transient oblique Hanle signals. Samples with a Co2MnSi spin source exhibited higher spin-injection efficiency and a larger nuclear field compared to samples with a Co50Fe50 spin source, suggesting that the spin polarization of Co2MnSi is higher. This higher polarization is promising for realizing future spintronic devices and for understanding spin interactions as well as spin-dependent transport properties in a semiconductor channel.

Akiho, Takafumi; Shan, Jinhai; Liu, Hong-xi; Matsuda, Ken-ichi; Yamamoto, Masafumi; Uemura, Tetsuya

2013-06-01

160

Three-dimensional optical manipulation of a single electron spin.

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

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

2013-03-01

161

Single-spin manipulation in a double quantum dot in the field of a micromagnet

NASA Astrophysics Data System (ADS)

The manipulation of single spins in double quantum dots by making use of the exchange interaction and a highly inhomogeneous magnetic field was discussed in Coish and Loss [Phys. Rev. B 75, 161302 (2007), 10.1103/PhysRevB.75.161302]. However, such large inhomogeneity is difficult to achieve through the slanting field of a micromagnet in current designs of lateral double dots. Therefore, we examine an analogous spin manipulation scheme directly applicable to realistic GaAs double dot setups. We estimate that typical gate times, realized at the singlet-triplet anticrossing induced by the inhomogeneous micromagnet field, can be a few nanoseconds. We discuss the optimization of initialization, read-out, and single-spin gates through suitable choices of detuning pulses and an improved geometry. We also examine the effect of nuclear dephasing and charge noise. The latter induces fluctuations of both detuning and tunneling amplitude. Our results suggest that this scheme is a promising approach for the realization of fast single-spin operations.

Chesi, Stefano; Wang, Ying-Dan; Yoneda, Jun; Otsuka, Tomohiro; Tarucha, Seigo; Loss, Daniel

2014-12-01

162

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

163

The spin-flip extended single excitation configuration interaction method.

An extension of the spin-flip single excitation configuration interaction (SF-CIS) method is introduced. The extension, abbreviated as SF-XCIS, includes all configurations in which no more than one virtual level of the high spin triplet reference becomes occupied and no more than one doubly occupied level becomes vacant. The number of such configurations is quadratic with molecule size, and the method is implemented in a direct algorithm whose cost scales in the same way with molecule size as CIS itself, thus permitting applications to large systems. Starting from a spin restricted triplet determinant, SF-XCIS yields spin-pure singlet, triplet, and quintet states, and treats both half-occupied reference orbitals in a fully balanced way to allow application to strongly correlated problems. Tests on bond dissociation in the HF molecule, the torsional potential of ethylene, and excited states of polyenes show encouraging improvements using SF-XCIS compared to SF-CIS and a previously suggested extension, the spin-complete CIS model. PMID:18715048

Casanova, David; Head-Gordon, Martin

2008-08-14

164

Cryogenic single-chip electron spin resonance detector.

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

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

2014-10-01

165

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

166

Towards force detected single electron spin resonance at room temperature

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

167

Single-spin superconductivity: Formulation and Ginzburg-Landau theory

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

Robert E. Rudd; Warren E. Pickett

1998-01-01

168

Quantum read-out and fast initialization of nuclear spin qubits with electric currents

Nuclear spin qubits have the longest coherence times in the solid state, but their quantum read-out and initialization is a great challenge. We present a theory for the interaction of an electric current with the nuclear spins of donor impurities in semiconductors. The theory yields a sensitivity criterion for quantum detection of nuclear spin states using electrically detected magnetic resonance, as well as an all electrical method for fast nuclear spin qubit initialization.

Noah Stemeroff; Rogerio de Sousa

2011-08-02

169

A silicon-based nuclear spin quantum computer

Quantum computers promise to exceed the computational efficiency of ordinary classical machines because quantum algorithms allow the execution of certain tasks in fewer steps. But practical implementation of these machines poses a formidable challenge. Here I present a scheme for implementing a quantum-mechanical computer. Information is encoded onto the nuclear spins of donor atoms in doped silicon electronic devices. Logical

B. E. Kane

1998-01-01

170

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

171

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-3He comagnetometer we demonstrate rotation sensitivity of 5 x 10(-7) rad s(-1) Hz(-1/2), equivalent to a magnetic field sensitivity of 2.5 fT/Hz(1/2). The rotation signal can be increased by a factor of 10 using 21Ne with a smaller magnetic moment. The comagnetometer is also a promising tool in searches for anomalous spin couplings beyond the standard model. PMID:16384290

Kornack, T W; Ghosh, R K; Romalis, M V

2005-12-01

172

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.

173

Nuclear spin selection rules in chemical reactions by angular momentum algebra

Nuclear spin selection rules in chemical reactions by angular momentum algebra Takeshi Oka of the representations of the permutationÂinversion group for both nuclear spin and rovibronic coordinate wavefunctions, those of the rotation group for nuclear spin wavefunction only are used. The method allows more

Oka, Takeshi

174

Dynamics of the Measurement of Nuclear Spins in a Solid-State Quantum Computer

We study numerically the process of nuclear spin measurement in a solid-state quantum computer of the type proposed by Kane by modeling the quantum dynamics of two coupled nuclear spins on $^{31}$P donors implanted in silicon. We estimate the minimum measurement time necessary for the reliable transfer of quantum information from the nuclear spin subsystem to the electronic subsystem. We

Gennady P. Berman; David K. Campbell; Gary D. Doolen; Kirill E. Nagaev

1999-01-01

175

Electron-nuclear spin dynamics in a mesoscopic solid-state quantum computer

We numerically simulate the process of nuclear spin measurement in Kane's quantum computer. For this purpose, we model the quantum dynamics of two coupled nuclear spins on 31P donors implanted in Si. We estimate the minimum time of measurement necessary for the reliable transfer of quantum information from the nuclear spin subsystem to the electronic subsystem. We also calculate the

Gennady P. Berman; David K. Campbell; Gary D. Doolen; Kirill E. Nagaev

1999-01-01

176

NASA Astrophysics Data System (ADS)

In a previous paper [M. Carravetta and M. H. Levitt, J. Chem. Phys. 122, 214505 (2005)], we presented the theory of long-lived nuclear spin singlet states in low magnetic field. In this paper, we consider the spin locking of long-lived singlet states in high magnetic field by the application of resonant radio frequency irradiation. We present theoretical results for unmodulated irradiation, including approximate analytical expressions for the singlet decay rate constants. We show the results of numerical simulations, which indicate that modulated radio frequency fields may be used to achieve broadband spin locking of singlet states but only in the case of a small difference in Larmor frequencies between the members of the spin pair.

Pileio, Giuseppe; Levitt, Malcolm H.

2009-06-01

177

NASA Astrophysics Data System (ADS)

Spin flip equation of motion coupled cluster (EOM-SF-CC) can correctly treat situations involving electronic degeneracies or near degeneracies, e.g., bond breaking, di- and tri-radicals, etc. However, for large systems EOM-SF-CC (even in single and double excitations) is computationally prohibitively expensive. Therefore, earlier approximations to EOM-SF-CC methods such as spin flip configuration interaction singles with perturbative doubles (SF-CIS(D)) have been proposed. In this work, we present a new perturbative approximation to EOM-SF-CC, which has been found to be more accurate than SF-CIS(D). The capabilities, advantages, and timings of the new approach have been demonstrated considering the singlet-triplet gaps in di- and triradicals as well as bond breaking examples. The method is extended to double spin flip EOM-CC and its capabilities have been tested.

Dutta, Achintya Kumar; Pal, Sourav; Ghosh, Debashree

2013-09-01

178

Quantum Information Atomic Spins, Stokes Vectors for Light and Canonical Variables Light University of Copenhagen Denmark April 2008 #12;Quantum Information Atomic Spins, Stokes Vectors for Light and Canonical Variables Light-Atom Interactions Single Atom Spin Squeezing Outlook Outline of the talk 1 Discuss

Budker, Dmitry

179

We report on optical detection of a single photostable Ce(3+) ion in an yttrium aluminium garnet (YAG) crystal and on its magneto-optical properties at room temperature. The spin quantum state of the emitting level of a single cerium ion in YAG can be initialized by a circularly polarized laser pulse. Coherent precession of the electron spin is read out by observing temporal behavior of circularly polarized fluorescence of the ion. This implies direct mapping of the spin quantum state of Ce(3+) ion onto the polarization state of the emitted photon and represents the quantum interface between a single spin and a single photon. PMID:24093236

Kolesov, Roman; Xia, Kangwei; Reuter, Rolf; Jamali, Mohammad; Stöhr, Rainer; Inal, Tugrul; Siyushev, Petr; Wrachtrup, Jörg

2013-09-20

180

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

181

Driven coherent oscillations of a single electron spin in a quantum dot

in the field of semiconductor quantum dots have made this system very fruitful as a host for the electron spinDriven coherent oscillations of a single electron spin in a quantum dot F. H. L. Koppens1 , C. Vandersypen1 The ability to control the quantum state of a single electron spin in a quantum dot

182

Room-temperature high-speed nuclear-spin quantum memory in diamond

Quantum memories provide intermediate storage of quantum information until it is needed for the next step of a quantum algorithm or a quantum communication process. Relevant figures of merit are therefore the fidelity with which the information can be written and retrieved, the storage time, and also the speed of the read-write process. Here, we present experimental data on a quantum memory consisting of a single $^{13}$C nuclear spin that is strongly coupled to the electron spin of a nitrogen-vacancy (NV) center in diamond. The strong hyperfine interaction of the nearest-neighbor carbon results in transfer times of 300 ns between the register qubit and the memory qubit, with an overall fidelity of 88 % for the write - storage - read cycle. The observed storage times of 3.3 ms appear to be limited by the T$_1$ relaxation of the electron spin. We discuss a possible scheme that may extend the storage time beyond this limit.

J. H. Shim; I. Niemeyer; J. Zhang; D. Suter

2013-01-03

183

Sivers Single-Spin Asymmetry in Photon-Jet Production

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

Bacchetta, Alessandro [Theory Group, Deutsches Elektronen-Synchroton DESY, 22603 Hamburg (Germany); Bomhof, Cedran; Mulders, Piet J. [Department of Physics and Astronomy, Vrije Universiteit Amsterdam, 1081 HV Amsterdam (Netherlands); D'Alesio, Umberto; Murgia, Francesco [INFN, Sezione di Cagliari and Dipartimento di Fisica, Universita di Cagliari, 09042 Monserrato (Italy)

2007-11-23

184

Coherent control is a fundamental challenge in quantum information processing (QIP). Our system of interest employs a local, isolated electron spin to coherently control nuclear spins. Coupled electron/nuclear spins are a ...

Abutaleb, Mohamed Osama

2010-01-01

185

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

186

High spin states in singly closed 143Pm

NASA Astrophysics Data System (ADS)

The high spin states in the N=82 odd-A 143Pm have been investigated by in-beam ?-spectroscopic techniques following the reactions 135Ba(11B,3n)143Pm at E=47 MeV and 133Cs(13C,3n)143Pm at E=63 MeV, respectively, using a gamma detector array, consisting of 12 Compton-supressed high purity germanium detectors and a multiplicity ball of 14 bismuth germanate elements. 28 new ? rays have been assigned to 143Pm on the basis of the ?-ray singles and ?-? coincidence data. The level scheme of 143Pm has been extended up to an excitation energy of 8.4 MeV and spin 47/2? and 24 new levels have been proposed. Spin-parity assignments for most of the newly proposed levels have been made using the measured directional correlation orientation ratios for strong transitions. The observed level structure is discussed in the light of available experimental data and a modest shell model calculation done by us, using the OXBASH code.

Bhattacharya, Sarmishtha; Chanda, Somen; Bandyopadhyay, Dipa; Kumar Basu, Swapan; Mukherjee, G.; Muralithar, S.; Singh, R. P.; Bhowmik, R. K.; Ghugre, S. S.

2000-08-01

187

Spin Density Matrices for Nuclear Density Functionals with Parity Violation

NASA Astrophysics Data System (ADS)

Within the context of the radial density functional [1], we apply the spin density matrix (SDM) used in atomic and molecular physics [2] to nuclear physics. The vector part of the SDM defines a ``hedgehog'' situation, which exists only if nuclear states contain some amount of parity violation. Thus, looking for the vector profile of the SDM could be used as a test for parity violation in nuclei. The difference between the scalar profile and the vector profile of the SDM will be illustrated by a toy model. [4pt] [1] B. G. Giraud, Phys. Rev. C 78, 014307 (2008).[0pt] [2] A. Goerling, Phys. Rev. A 47, 2783 (1993).

Barrett, Bruce; Giraud, Bertrand

2010-11-01

188

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

189

Ab initio calculations combining density-functional theory and nonequilibrium Green's function are performed to investigate the effects of either single B atom or single N atom dopant in zigzag-edged graphene nanoribbons (ZGNRs) with the ferromagnetic state on the spin-dependent transport properties and thermospin performances. A spin-up (spin-down) localized state near the Fermi level can be induced by these dopants, resulting in a half-metallic property with 100% negative (positive) spin polarization at the Fermi level due to the destructive quantum interference effects. In addition, the highly spin-polarized electric current in the low bias-voltage regime and single-spin negative differential resistance in the high bias-voltage regime are also observed in these doped ZGNRs. Moreover, the large spin-up (spin-down) Seebeck coefficient and the very weak spin-down (spin-up) Seebeck effect of the B(N)-doped ZGNRs near the Fermi level are simultaneously achieved, indicating that the spin Seebeck effect is comparable to the corresponding charge Seebeck effect. PMID:25591376

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

2015-01-14

190

$?$-nuclear spin-orbit coupling from two-pion exchange

Using SU(3) chiral perturbation theory we calculate the density-dependent complex-valued spin-orbit coupling strength $U_{\\Sigma ls}(k_f)+ i W_{\\Sigma ls}(k_f)$ of a $\\Sigma$ hyperon in the nuclear medium. The leading long-range $\\Sigma N$ interaction arises from iterated one-pion exchange with a $\\Lambda$ or a $\\Sigma$ hyperon in the intermediate state. We find from this unique long-range dynamics a sizeable ``wrong-sign'' spin-orbit coupling strength of $U_{\\Sigma ls}(k_{f0}) \\simeq -20$ MeVfm$^2$ at normal nuclear matter density $\\rho_0 = 0.16 $fm$^{-3}$. The strong $\\Sigma N\\to \\Lambda N$ conversion process contributes at the same time an imaginary part of $W_{\\Sigma ls}(k_{f0}) \\simeq -12$ MeVfm$^2$. When combined with estimates of the short-range contribution the total $\\Sigma$-nuclear spin-orbit coupling becomes rather weak.

N. Kaiser

2007-11-14

191

Quantum Measurement of a Single Spin using Magnetic Resonance Force Microscopy

Single-spin detection is one of the important challenges facing the development of several new technologies, e.g. single-spin transistors and solid-state quantum computation. Magnetic resonance force microscopy with a cyclic adiabatic inversion, which utilizes a cantilever oscillations driven by a single spin, is a promising technique to solve this problem. We have studied the quantum dynamics of a single spin interacting with a quasiclassical cantilever. It was found that in a similar fashion to the Stern-Gerlach interferometer the quantum dynamics generates a quantum superposition of two quasiclassical trajectories of the cantilever which are related to the two spin projections on the direction of the effective magnetic field in the rotating reference frame. Our results show that quantum jumps will not prevent a single-spin measurement if the coupling between the cantilever vibrations and the spin is small in comparison with the amplitude of the radio-frequency external field.

G. P. Berman; F. Borgonovi; G. Chapline; S. A. Gurvitz; P. C. Hammel; D. V. Pelekhov; A. Suter; V. I. Tsifrinovich

2001-08-06

192

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

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. PMID:25150719

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

2014-09-01

193

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

194

NASA Astrophysics Data System (ADS)

A new polarization propagator approach to indirect nuclear spin-spin coupling constantans is formulated within the framework of the algebraic-diagrammatic construction (ADC) approximation and implemented at the level of the strict second-order approximation scheme, ADC(2). The ADC approach possesses transparent computational procedure operating with Hermitian matrix quantities defined with respect to physical excitations. It is size-consistent and easily extendable to higher orders via the hierarchy of available ADC approximation schemes. The ADC(2) method is tested in the first applications to HF, N2, CO, H2O, HCN, NH3, CH4, C2H2, PH3, SiH4, CH3F, and C2H4. The calculated indirect nuclear spin-spin coupling constants are in good agreement with the experimental data and results of the second-order polarization propagator approximation method. The computational effort of the ADC(2) scheme scales as n5 with respect to the number of molecular orbitals n, which makes this method promising for applications to larger molecules.

Rusakova, I. L.; Krivdin, L. B.; Rusakov, Yu. Yu.; Trofimov, A. B.

2012-07-01

195

High Speed Single Dopant Spin Manipulation with a Single Electrical Gate

NASA Astrophysics Data System (ADS)

Ultra-low-power computation with spin based electronics can be achieved through coherent spin manipulation. Naturally occurring Mn ions with a bound hole in GaAs provide a uniform system with the potential for fast, all electrical spin manipulation applicable to high-density scalable spin-based electronics [1] and can be probed optically [2]. In an effort to increase device scalability by utilizing a single gate we consider a configuration in which three fields, DC magnetic, DC electric and AC electric, are parallel. With a DC magnetic field of 2.5 T and total electric field strength of 200 kV/cm, we predict Rabi periods on the order of picoseconds with high visibilities. Assuming each Mn experiences a random electric field, which modifies its spin precession, we performed an ensemble calculation using this Hamiltonian to predict polarization curves from a PL measurement on low concentration Mn in GaAs. In addition we calculate how these curves are affected by a bias DC electric field.[4pt][1] J.-M Tang, Jeremy Levy, and M. E. Flatt/'e, Phys. Rev. Lett. 97, 106803 (2006).[0pt] [2] R. C. Myers, et al. Nature Mat. 7, 203 (2008).

Povilus, Victoria; Tang, J.-M.; Flatté, M. E.

2009-11-01

196

Nuclear states and shapes at high spin. [Good review

As angular momentum is added to a nucleus, the balance of forces acting upon it to determine its shape, moment of inertia, mode of rotation, and type of level structure may undergo a series of changes. At relatively low spins a deformed nucleus will rotate collectively, and one may see the effect of Coriolis antipairing in gradually increasing the moment of inertia. Around spin 12 to 16 h-bar there may be an abrupt change (backbending) when a pair of high-j nucleons unpairs and the nucleons align with the axis of rotation; this process allows the nucleus to slow its collective rotation. This process, the start of a sharing of angular momentum between single-particle motion and the collective rotation, gives a lower total energy and corresponds to a change toward triaxiality in the shape of the nucleus. At much higher spins discrete ..gamma..-ray transitions can no longer be observed. This is the regime of continuum spectra; all the information on these high-spin states (to 65 h-bar) is contained in these continuum cascades. Knowledge is accumulating on how to study these spectra, experimentally and theoretically, and new techniques offer promise of revealing a great deal of information about the shapes and properties of very high spin states. 71 references, 34 figures.

Diamond, R.M.

1980-08-01

197

Solid effect in magic angle spinning dynamic nuclear polarization

NASA Astrophysics Data System (ADS)

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 ? _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.

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

2012-08-01

198

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.

199

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

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. [RIKEN Nishina Center, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Asahi, K.; Inoue, T.; Uchida, M.; Hatakeyama, N.; Tsuchiya, M.; Kagami, S. [Department of Physics, Tokyo Institute of Technology, Oh-okayama 2-12-1, Meguro, Tokyo 152-8551 (Japan)

2009-08-04

200

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

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

Su, Zhongbo; Wei, Xinyuan; Yang, Zhongqin, E-mail: zyang@fudan.edu.cn [State Key Laboratory of Surface Physics and Key Laboratory for Computational Physical Sciences (MOE) and Department of Physics, Fudan University, Shanghai 200433 (China); An, Yipeng [College of Physics and Electronic Engineering and Institute of Computational Materials Design, Henan Normal University, Xinxiang 453007 (China)

2014-05-28

201

NASA Astrophysics Data System (ADS)

Fully relativistic calculations of the isotropic and anisotropic parts of both indirect nuclear spin-spin couplings 1)J(X-H and 2)J(H-H and nuclear magnetic shieldings sigma(X) and sigma(H) for the group-15 and -16 hydrides are presented. Relativistic calculations were performed with Dirac-Fock wave functions and the random phase approximation method. Results are compared to its nonrelativistic counterpart. Paramagnetic and diamagnetic contributions to the nuclear magnetic shielding constants are also reported. We found very large relativistic corrections to both properties in the sixth-row hydrides (BiH3 and PoH2). Our calculations of the relativistic corrections to the isotropic part of sigma at the heavy nucleus X show that it is roughly proportional to Z3.2 in both series of molecules. Paramagnetic term sigmap is more sensitive to the effects of relativity than the diamagnetic one sigmad, even though both have a behavior proportional to third power of the nuclear charge Z.

Gomez, Sergio S.; Romero, Rodolfo H.; Aucar, Gustavo A.

2002-11-01

202

Quantum Dot Spin Valves Controlled by Single Molecule Magnets

NASA Astrophysics Data System (ADS)

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

Rostamzadeh Renani, Fatemeh; Kirczenow, George

2013-03-01

203

Calculation of TMD Evolution for Transverse Single Spin Asymmetry Measurements

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

Mert Aybat, Ted Rogers, Alexey Prokudin

2012-06-01

204

Single Transverse-Spin Asymmetries at Large-x

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

Brodsky, Stanley J.; Yuan, Feng

2006-10-24

205

Single Spin Asymmetries from the Mainz A4 Experiment

NASA Astrophysics Data System (ADS)

The A4 collaboration at the MAMI accelerator in Mainz measures single spin asymmetries in the cross section of elastic scattering of polarized electrons off unpolarized protons. The electrons can be polarized longitudinally as well as transversely. Longitudinal polarization leads to a parity violating (PV) asymmetry from which the contribution of strange sea quarks to the vector form factors of the proton can be derived. Transverse polarization leads to an azimuthal ?-dependent asymmetry which gives acces to the imaginary part of the 2 ?-exchange amplitude. Measurements at forward angles ?=(35±5)° and two different momentum transfers Q 2 of 0.23 ( and 0.11 ( have been performed so far. Measurements at backward angles ?=(145±5)° are in preparation.

Baunack, S.

2005-06-01

206

Effective ergodicity in single-spin-flip dynamics.

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. PMID:25314429

Süzen, Mehmet

2014-09-01

207

Global fitting of single spin asymmetry: an attempt

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

Alexey Prokudin,Zhong-Bo Kang

2012-04-01

208

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

209

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

210

The water-endofullerene H{sub 2}O@C{sub 60} 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 H{sub 2}O 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 H{sub 2}O molecules is catalysed by {sup 13}C nuclei present in the cages.

Mamone, Salvatore, E-mail: s.mamone@soton.ac.uk; Concistrè, Maria; Carignani, Elisa; Meier, Benno; Krachmalnicoff, Andrea; Johannessen, Ole G.; Denning, Mark; Carravetta, Marina; Whitby, Richard J.; Levitt, Malcolm H., E-mail: mhl@soton.ac.uk [School of Chemistry, University of Southampton, Southampton SO17 1BJ (United Kingdom); Lei, Xuegong; Li, Yongjun [Department of Chemistry, Columbia University, New York, New York 10027 (United States)] [Department of Chemistry, Columbia University, New York, New York 10027 (United States); Goh, Kelvin; Horsewill, Anthony J. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)] [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

2014-05-21

211

Dynamics of the Measurement of Nuclear Spins in a Solid-State Quantum Computer

We study numerically the process of nuclear spin measurement in a solid-state\\u000aquantum computer of the type proposed by Kane by modeling the quantum dynamics\\u000aof two coupled nuclear spins on $^{31}$P donors implanted in silicon. We\\u000aestimate the minimum measurement time necessary for the reliable transfer of\\u000aquantum information from the nuclear spin subsystem to the electronic\\u000asubsystem. We

Gennady P. Berman; David K. Campbell; Gary D. Doolen; Kirill E. Nagaev

1999-01-01

212

Electron-Nuclear Spin Dynamics in a Mesoscopic Solid-State Quantum Computer

We numerically simulate the process of nuclear spin measurement in Kane's quantum computer. For this purpose, we model the quantum dynamics of two coupled nuclear spins located on {sup 31}P donors implanted in Si. We estimate the minimum time of measurement necessary for the reliable transfer of quantum information from the nuclear spin subsystem to the electronic one and the probability of error for typical values of external noise.

Berman, G.P.; Campbell, D.K.; Doolen, G.D.; Nagaev, K.E.

1998-12-07

213

Quadrupolar spectra of nuclear spins in strained InxGa1-xAs quantum dots

NASA Astrophysics Data System (ADS)

Self-assembled quantum dots (QDs) are born out of lattice mismatched ingredients where strain plays an indispensable role. Through the electric quadrupolar coupling, strain affects the magnetic environment as seen by the nuclear spins. To guide prospective single-QD nuclear magnetic resonance (NMR), as well as dynamic nuclear spin polarization experiments, an atomistic insight to the strain and quadrupolar field distributions is presented. A number of implications of the structural and compositional profile of the QD have been identified. A high aspect ratio of the QD geometry enhances the quadrupolar interaction. The inclined interfaces introduce biaxiality and the tilting of the major quadrupolar principal axis away from the growth axis; the alloy mixing of gallium into the QD enhances both of these features while reducing the quadrupolar energy. Regarding the NMR spectra, both Faraday and Voigt geometries are investigated, unraveling in the first place the extend of inhomogeneous broadening and the appearance of the normally forbidden transitions. Moreover, it is shown that from the main extend of the NMR spectra the alloy mole fraction of a single QD can be inferred. By means of the element-resolved NMR intensities it is found that In nuclei has a factor of 5 dominance over those of As. In the presence of an external magnetic field, the borderlines between the quadrupolar and Zeeman regimes are extracted as 1.5 T for In and 1.1 T for As nuclei. At these values the nuclear spin depolarization rates of the respective nuclei get maximized due to the noncollinear secular hyperfine interaction with a resident electron in the QD.

Bulutay, Ceyhun

2012-03-01

214

Nuclear spin-spin coupling in a van der Waals-bonded system: xenon dimer.

Nuclear spin-spin coupling over van der Waals bond has recently been observed via the frequency shift of solute protons in a solution containing optically hyperpolarized (129)Xe nuclei. We carry out a first-principles computational study of the prototypic van der Waals-bonded xenon dimer, where the spin-spin coupling between two magnetically non-equivalent isotopes, J((129)Xe - (131)Xe), is observable. We use relativistic theory at the four-component Dirac-Hartree-Fock and Dirac-density-functional theory levels using novel completeness-optimized Gaussian basis sets and choosing the functional based on a comparison with correlated ab initio methods at the nonrelativistic level. J-coupling curves are provided at different levels of theory as functions of the internuclear distance in the xenon dimer, demonstrating cross-coupling effects between relativity and electron correlation for this property. Calculations on small Xe clusters are used to estimate the importance of many-atom effects on J((129)Xe - (131)Xe). Possibilities of observing J((129)Xe - (131)Xe) in liquid xenon are critically examined, based on molecular dynamics simulation. A simplistic spherical model is set up for the xenon dimer confined in a cavity, such as in microporous materials. It is shown that the on the average shorter internuclear distance enforced by the confinement increases the magnitude of the coupling as compared to the bulk liquid case, rendering J((129)Xe - (131)Xe) in a cavity a feasible target for experimental investigation. PMID:23514495

Vaara, Juha; Hanni, Matti; Jokisaari, Jukka

2013-03-14

215

Radioactive nuclear beams and the North American IsoSpin Laboratory (ISL) initiative

Radioactive nuclear beams (RNBs) offer exciting new research opportunities in fields as diverse as nuclear structure, nuclear reactions, astrophysics atomic, materials, and applied science. Their realization in new accelerator complexes also offers important technical challenges. Some of the nuclear physics possibilities afforded by RNBs, with emphasis on low spin nuclear structure, are discussed, accompanied by an outline of the ISL initiative and its status.

Casten, R.F.

1992-12-01

216

Radioactive nuclear beams and the North American IsoSpin Laboratory (ISL) initiative

Radioactive nuclear beams (RNBs) offer exciting new research opportunities in fields as diverse as nuclear structure, nuclear reactions, astrophysics atomic, materials, and applied science. Their realization in new accelerator complexes also offers important technical challenges. Some of the nuclear physics possibilities afforded by RNBs, with emphasis on low spin nuclear structure, are discussed, accompanied by an outline of the ISL initiative and its status.

Casten, R.F.

1992-01-01

217

Nondestructive optical measurements of a single electron spin in a quantum dot.

Kerr rotation measurements on a single electron spin confined in a charge-tunable semiconductor quantum dot demonstrate a means to directly probe the spin off-resonance, thus minimally disturbing the system. Energy-resolved magneto-optical spectra reveal information about the optically oriented spin polarization and the transverse spin lifetime of the electron as a function of the charging of the dot. These results represent progress toward the manipulation and coupling of single spins and photons for quantum information processing. PMID:17095655

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

2006-12-22

218

Tunable spin loading and T1 of a silicon spin qubit measured by single-shot readout.

We demonstrate single-shot readout of a silicon quantum dot spin qubit, and we measure the spin relaxation time T1. We show that the rate of spin loading can be tuned by an order of magnitude by changing the amplitude of a pulsed-gate voltage, and the fraction of spin-up electrons loaded can also be controlled. This tunability arises because electron spins can be loaded through an orbital excited state. Using a theory that includes excited states of the dot and energy-dependent tunneling, we find that a global fit to the loading rate and spin-up fraction is in good agreement with the data. PMID:21568595

Simmons, C B; Prance, J R; Van Bael, B J; Koh, Teck Seng; Shi, Zhan; Savage, D E; Lagally, M G; Joynt, R; Friesen, Mark; Coppersmith, S N; Eriksson, M A

2011-04-15

219

of hyperfine interactions between nuclear spins and conduction electrons, gN is a gyromagnetic ratio of the nucleus, geff is an effective gyromagnetic ratio of conducting electrons, B is a Bohr magneton, and 00 ?Hq

Demler, Eugene

220

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

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

Ghosh, Bahniman, E-mail: bghosh@utexas.edu [Microelectronics Research Center, 10100, Burnet Road, Bldg. 160, University of Texas at Austin, Austin, TX, 78758 (United States)] [Microelectronics Research Center, 10100, Burnet Road, Bldg. 160, University of Texas at Austin, Austin, TX, 78758 (United States); Katiyar, Saurabh; Salimath, Akshaykumar, E-mail: salimath@iitk.ac.in [Department of Electrical Engineering, Indian Institute of Technology, Kanpur 208016 (India)] [Department of Electrical Engineering, Indian Institute of Technology, Kanpur 208016 (India)

2014-01-15

221

Quantum state tomography for strongly coupled nuclear spin systems

NASA Astrophysics Data System (ADS)

We perform quantum state tomography (QST) in a three-qubit system consisting of strongly coupled nuclear spins, known in the NMR literature as A B X systems. We find that the number of experiments necessary to perform QST in such systems can be reduced with respect to those containing three qubits weakly coupled, which reduces the experimental effort required for the complete density-matrix reconstruction. To test the procedure we implement the full protocol for quantum teleportation. The tomographic results demonstrate that the density matrix can be reconstructed with fewer operations and high fidelity.

Vind, Fatemeh Anvari; Souza, A. M.; Sarthour, R. S.; Oliveira, I. S.

2014-12-01

222

NMR response of nuclear-spin helix in quantum wires with hyperfine and spin-orbit interaction

NASA Astrophysics Data System (ADS)

We calculate the nuclear magnetic resonance (NMR) response of a quantum wire where at low temperature a self-sustained electron-nuclear spin order is created. Our model includes the electron mediated Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange, electron spin-orbit interactions, nuclear dipolar interactions, and the static and oscillating NMR fields, all of which play an essential role. The paramagnet to helimagnet transition in the nuclear system is reflected in an unusual response: it absorbs at a frequency given by the internal RKKY exchange field, rather than the external static field, whereas the latter leads to a splitting of the resonance peak.

Stano, Peter; Loss, Daniel

2014-11-01

223

Electron Spin Resonance of an Irradiated Single Crystal of 5-Chlorouridine

Electron spin resonance signals from radicals of different types have been observed in ?-irradiated 5-chlorouridine. The strongest absorption, a broad resonance with g values ranging from 2.2 to 3.0, must arise from spin density concentrated on chlorine, probably from trapped atoms. However, hyperfine structure expected from Cl nuclei could not be resolved, evidently because of the low symmetry and diversity of the trapping sites and the large anisotropy in the nuclear coupling and g tensor. A very much weaker resonance, which in the single crystal has a resolvable hyperfine structure, was found to be similar to that observed in normal uridine subjected to thermal H atoms. It is concluded that an H atom, probably released by irradiation from the ribose group, replaces the Cl atom on the basic ring to form normal uridine, and that a second H atom later adds to the uridine to form the observed H-addition radical. The differences in the electron spin resonance constants of this radical from those of uridine bombarded with H can be attributed to the proximity of the trapped Cl atoms and to differences in the crystal structure of the chlorouridine from that of normal uridine. PMID:4332244

Reiss, Keith W.; Gordy, Walter

1971-01-01

224

We report on optical detection of a single photostable Ce3+ ion in an yttrium aluminium garnet (YAG) crystal and on its magneto-optical properties at room temperature. The quantum state of an electron spin of the emitting level of cerium ion in YAG can be initialized by circularly polarized laser pulse. Furthermore, its quantum state can be read out by observing temporal behaviour of circularly polarized fluorescence of the ion. This implies direct mapping of the spin quantum state of Ce3+ ion onto the polarization state of the emitted photon and represents one-way quantum interface between a single spin and a single photon.

Kolesov, Roman; Reuter, Rolf; Stoehr, Rainer; Inal, Tugrul; Siyushev, Petr; Wrachtrup, Joerg

2013-01-01

225

NASA Astrophysics Data System (ADS)

A general description of magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectra arising from a pair of chemically equivalent nuclear spins is presented in terms of average Hamiltonian theory (AHT). In general, the MAS NMR spectra of such a spin-pair exhibit a spinning frequency dependent four-line pattern from which it is possible to extract the indirect spin-spin coupling constant, J, involving the ``equivalent'' spin pair. Explicit expressions for the spinning frequency dependence of the four-line pattern have been derived using AHT. In principle, correction terms to any order can be included; however, consideration of correction terms up to and including third order appear to be sufficient to interpret the most important features characteristic of J-recoupled spectra involving chemically equivalent spin pairs. The average Hamiltonian theory predicts three different general types of recoupling patterns. The type of recoupling pattern observed for a particular chemically equivalent spin pair is predicted to depend on the relative magnitudes of the indirect homonuclear coupling constant, J, the direct homonuclear dipolar coupling constant, R, the magnitude of the instantaneous chemical shift difference between the ``equivalent'' spins in frequency units, and the MAS spinning frequency. All reported examples of spinning frequency dependent MAS NMR spectra arising from a pair of chemically equivalent spins can be understood using the theoretical expressions derived here. As an example, we interpret the unusual J-recoupling pattern observed in 31P MAS NMR spectra of Hg(PPh3)2(NO3)2. The recoupling pattern is unusual in that 2J(P,P) is given by the separation of alternate lines in the four-line pattern. Similar unusual J-recoupling patterns were first reported by Eichele, Wu, and Wasylishen.

Wu, Gang; Wasylishen, Roderick E.

1993-04-01

226

Modeling and simulations of a single-spin measurement using MRFM

We review the quantum theory of a single-spin magnetic resonance force microscopy (MRFM). We concentrate on the novel technique called oscillating cantilever-driven adiabatic reversals (OSCARs), which has been used for a single-spin detection. First we describe the quantum dynamics of the cantilever-spin system using simple estimates in the spirit of the mean field approximation. Then we present the results of

Gennady P. Berman; Fausto Borgonovi; Vyacheslav N. Gorshkov; Vladimir I. Tsifrinovich

2005-01-01

227

In a heteronuclear system, the indirect detection of nuclei S, of weak gyromagnetic ratio, coupled to nuclei I, of strong gyromagnetic ratio, is accomplished by generation of zero and double quantum coherence between the I and S spin systems, during a preparatory period, TP. The zero and double quantum transitions are then interchanged at the midpoint of the evolution period, T1, producing an echo modulated only by S and I-I interactions at the end of the period T1, at which time the zero and double quantum coherence is then converted to I spin single quantum coherence yielding a free induction decay wave form S(T2) for given T1. The period, T1, is then varied to obtain a two-dimensional function S(T1, T2) which is then fully transformed to the frequency domain obtaining S(..omega..1,..omega..2) whereby the chemical shift of the coupled S spin is obtained along the ..omega..1 axis and the chemical shift of the I spin is obtained along the ..omega..2 axis.

Muller, L.

1980-12-09

228

Nuclear Spin Relaxation of Polycrystalline ^129Xe at Low Fields

NASA Astrophysics Data System (ADS)

Through spin exchange techniques, it is possible to achieve upwards of 30% nuclear spin polarization in ^129Xe with an NMR signal enhancement of some 5 orders of magnitude over typical thermal signals. Hyperpolarized ^129Xe has thus found application in several leading-edge technologies. At 1 T and 4.2 K the characteristic relaxation time of enriched polycrystalline ^129Xe (86% ^129Xe, 0.1% ^131Xe) is well over 200 hours, sufficient for long-term storage and transport. At more convenient fields from 1 to 500 G, significant structure in relaxation times vs. magnetic field is seen; the most prominent being a sharp local maximum of 800 min at ? 4 G. Such structure has not been observed in previous measurements of natural Xe. Below 20 K, relaxation can be attributed either to cross relaxation with ^131Xe, mediated by spin diffusion (Gatzke, et al., PRL 70, 690 (1993)) or to paramagnetic impurities. We report measurements of ^129Xe relaxation as a function of magnetic field, temperature and Xe isotopic content and compare with expected theoretical behaviors.

Samuelson, G.; Su, T.; Saam, B.

2003-05-01

229

A new method for measuring the spin of the electrically charged ground state excitations m the Q$j~j quantum Hall effect ia proposed and demonstmted for the tirst time in GaAs/AIGaAs nndtiquantum wells. The method is &sed on the nuclear spin orientation dependence of" the 2D dc conductivity y in the quantum Hall regime due to the nuclear hyperfine interaction. As a demonstration of this method the spin of the electrically charged excitations of the ground state is determined at filling factor v = 1.

Bowers, C.R.; Reno, J.L.; Simmons, J.A.; Vitkalov, S.A.

1998-12-01

230

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 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

231

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

232

NASA Astrophysics Data System (ADS)

We theoretically study the interplay of spin-orbit and hyperfine interactions in dynamical nuclear polarization in two-electron semiconductor double quantum dots near the singlet-triplet (S -T+ ) anticrossing. The goal of the scheme under study is to extend the singlet-triplet (S -T0 ) qubit decoherence time T2* by dynamically transferring the polarization from the electron spins to the nuclear spins. This polarization transfer is achieved by cycling the electron spins over the S -T+ anticrossing. Here, we investigate, both quantitatively and qualitatively, how this hyperfine-mediated dynamical polarization transfer is influenced by the Rashba and Dresselhaus spin-orbit interaction. In addition to T2*, we determine the singlet return probability Ps, a quantity that can be measured in experiments. Our results suggest that the spin-orbit interaction establishes a mechanism that can polarize the nuclear spins in the direction opposite to that of hyperfine-mediated nuclear spin polarization. In materials with relatively strong spin-orbit coupling, this interplay of spin-orbit and hyperfine-mediated nuclear spin polarizations prevents any notable increase in the S -T0 qubit decoherence time T2*.

Ran?i?, Marko J.; Burkard, Guido

2014-12-01

233

Picosecond coherent optical manipulation of a single electron spin in a quantum dot.

Most schemes for quantum information processing require fast single-qubit operations. For spin-based qubits, this involves performing arbitrary coherent rotations of the spin state on time scales much faster than the spin coherence time. By applying off-resonant, picosecond-scale optical pulses, we demonstrated the coherent rotation of a single electron spin through arbitrary angles up to pi radians. We directly observed this spin manipulation using time-resolved Kerr rotation spectroscopy and found that the results are well described by a model that includes the electronnuclear spin interaction. Measurements of the spin rotation as a function of laser detuning and intensity confirmed that the optical Stark effect is the operative mechanism. PMID:18420929

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

2008-04-18

234

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

NASA Astrophysics Data System (ADS)

A stimulated wave of polarization, which implements a simple mechanism of quantum amplification, is experimentally demonstrated in a chain of four J-coupled nuclear spins, irradiated by a weak radio-frequency transverse field. The 'quantum domino' dynamics, a wave of flipped spins triggered by a flip of the first spin, has been observed in fully 13C-labelled sodium butyrate.

Lee, Jae-Seung; Adams, Travis; Khitrin, A. K.

2007-04-01

235

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

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

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

2015-02-01

236

Coherent control of single spins in silicon carbide at room temperature

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

237

Non-destructive Kerr rotation measurements of a single spin in a quantum dot

NASA Astrophysics Data System (ADS)

A single electron spin in a quantum dot forms a natural two state system for use in quantum information processing. The ability to measure this spin without destroying the system is an important step towards observing various quantum measurement-related phenomena. In contrast to previous experiments, we have performed non-destructive Kerr rotation measurements on a single electron spin confined in a charge-tunable semiconductor quantum dot. This measurement technique provides a means to directly probe the spin off-resonance, thus minimally disturbing the system. Energy-resolved Kerr rotation spectra demonstrate that we are probing a single electron, and also yield information about the optically-pumped spin polarization as a function of quantum dot charging. These results point the way towards quantum non-demolition measurements and optically-mediated entanglement of spins in the solid state. J. Berezovsky et al., Science Express, 9 November 2006, (10.1126/science.1133862).

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

2007-03-01

238

NASA Astrophysics Data System (ADS)

Spin labeling of molecules with paramagnetic ions is an important approach for determining molecular structure; however, current ensemble techniques lack the sensitivity to detect few isolated spins. In this paper, we demonstrate two-dimensional nanoscale imaging of paramagnetic gadolinium compounds using scanning relaxometry of a single nitrogen-vacancy (NV) center in diamond. Gadopentetate dimeglumine attached to an atomic-force microscope tip is controllably interacted with and detected by the NV center by virtue of the fact that the NV exhibits fast relaxation in the fluctuating magnetic field generated by electron spin flips in the gadolinium. Using this technique, we demonstrate a reduction in the T1 relaxation time of the NV center by over 2 orders of magnitude, probed with a spatial resolution of 20 nm. Our result exhibits the viability of the technique for imaging individual spins attached to complex nanostructures or biomolecules, along with studying the magnetic dynamics of isolated spins.

Pelliccione, M.; Myers, B. A.; Pascal, L. M. A.; Das, A.; Bleszynski Jayich, A. C.

2014-11-01

239

Anomalous-filling-factor-dependent nuclear-spin polarization in a 2D electron system.

Spin-related electronic phase transitions in the fractional quantum Hall regime are accompanied by a large change in resistance. Combined with their sensitivity to spin orientation of nuclei residing in the same plane as the 2D electrons, they offer a convenient electrical probe to carry out nuclear magnetometry. Despite conditions which should allow both electronic and nuclear-spin subsystems to approach thermodynamic equilibrium, we uncover for the nuclei a remarkable and strongly electronic filling-factor-dependent deviation from the anticipated thermal nuclear-spin polarization. PMID:14995804

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

2004-02-27

240

Optical pump-probe measurements of local nuclear spin coherence in semiconductor quantum wells.

We demonstrate local manipulation and detection of nuclear spin coherence in semiconductor quantum wells by an optical pump-probe technique combined with pulse rf NMR. The Larmor precession of photoexcited electron spins is monitored by time-resolved Kerr rotation (TRKR) as a measure of nuclear magnetic field. Under the irradiation of resonant pulsed rf magnetic fields, Rabi oscillations of nuclear spins are traced by TRKR signals. The intrinsic coherence time evaluated by a spin-echo technique reveals the dependence on the orientation of the magnetic field with respect to the crystalline axis as expected by the nearest neighbor dipole-dipole interaction. PMID:16606048

Sanada, H; Kondo, Y; Matsuzaka, S; Morita, K; Hu, C Y; Ohno, Y; Ohno, H

2006-02-17

241

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

242

Coherent dynamics of coupled electron and nuclear spin qubits in diamond.

Understanding and controlling the complex environment of solid-state quantum bits is a central challenge in spintronics and quantum information science. Coherent manipulation of an individual electron spin associated with a nitrogen-vacancy center in diamond was used to gain insight into its local environment. We show that this environment is effectively separated into a set of individual proximal 13C nuclear spins, which are coupled coherently to the electron spin, and the remainder of the 13C nuclear spins, which cause the loss of coherence. The proximal nuclear spins can be addressed and coupled individually because of quantum back-action from the electron, which modifies their energy levels and magnetic moments, effectively distinguishing them from the rest of the nuclei. These results open the door to coherent manipulation of individual isolated nuclear spins in a solid-state environment even at room temperature. PMID:16973839

Childress, L; Gurudev Dutt, M V; Taylor, J M; Zibrov, A S; Jelezko, F; Wrachtrup, J; Hemmer, P R; Lukin, M D

2006-10-13

243

Dynamics of nuclear spin measurement in a mesoscopic solid-state quantum computer

We study numerically the process of nuclear spin measurement in a solid-state quantum computer of the type proposed by Kane, by calculating the quantum dynamics of two coupled nuclear spins on 31 P donors implanted in 28 Si. We estimate the time of the `quantum swap operation' - the minimum measurement time required for the reliable transfer of quantum information

Gennady P. Berman; David K. Campbell; Gary D. Doolen; Kirill E. Nagaev

2000-01-01

244

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

245

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

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

2014-01-01

246

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

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

2014-01-01

247

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

NASA Astrophysics Data System (ADS)

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

Lindebaum, Stephan; König, Jürgen

2011-12-01

248

Coherent control of two nuclear spins using the anisotropic hyperfine interaction

We demonstrate coherent control of two nuclear spins mediated by the magnetic resonance of a hyperfine-coupled electron spin. This control is used to create a double nuclear coherence in one of the two electron spin manifolds, starting from an initial thermal state, in direct analogy to the creation of an entangled (Bell) state from an initially pure unentangled state. We identify challenges and potential solutions to obtaining experimental gate fidelities useful for quantum information processing in this type of system.

Yingjie Zhang; Colm A. Ryan; Raymond Laflamme; Jonathan Baugh

2011-09-02

249

Spin-dependent quasiparticle transport in aluminum single-electron transistors.

We investigate the effect of Zeeman splitting on quasiparticle transport in normal-superconducting-normal (NSN) aluminum single-electron transistors (SETs). In the above-gap transport, the interplay of Coulomb blockade and Zeeman splitting leads to spin-dependence of the sequential tunneling. This creates regimes where either one or both spin species can tunnel onto or off the island. At lower biases, spin-dependence of the single quasiparticle state is studied, and operation of the device as a bipolar spin filter is suggested. PMID:17026322

Ferguson, A J; Andresen, S E; Brenner, R; Clark, R G

2006-08-25

250

A 3D-Printed High Power Nuclear Spin Polarizer

Three-dimensional printing with high-temperature plastic is used to enable spin exchange optical pumping (SEOP) and hyperpolarization of xenon-129 gas. The use of 3D printed structures increases the simplicity of integration of the following key components with a variable temperature SEOP probe: (i) in situ NMR circuit operating at 84 kHz (Larmor frequencies of 129Xe and 1H nuclear spins), (ii) <0.3 nm narrowed 200 W laser source, (iii) in situ high-resolution near-IR spectroscopy, (iv) thermoelectric temperature control, (v) retroreflection optics, and (vi) optomechanical alignment system. The rapid prototyping endowed by 3D printing dramatically reduces production time and expenses while allowing reproducibility and integration of “off-the-shelf” components and enables the concept of printing on demand. The utility of this SEOP setup is demonstrated here to obtain near-unity 129Xe polarization values in a 0.5 L optical pumping cell, including ~74 ± 7% at 1000 Torr xenon partial pressure, a record value at such high Xe density. Values for the 129Xe polarization exponential build-up rate [(3.63 ± 0.15) × 10?2 min?1] and in-cell 129Xe spin?lattice relaxation time (T1 = 2.19 ± 0.06 h) for 1000 Torr Xe were in excellent agreement with the ratio of the gas-phase polarizations for 129Xe and Rb (PRb ~ 96%). Hyperpolarization-enhanced 129Xe gas imaging was demonstrated with a spherical phantom following automated gas transfer from the polarizer. Taken together, these results support the development of a wide range of chemical, biochemical, material science, and biomedical applications. PMID:24400919

Nikolaou, Panayiotis; Coffey, Aaron M.; Walkup, Laura L.; Gust, Brogan M.; LaPierre, Cristen D.; Koehnemann, Edward; Barlow, Michael J.; Rosen, Matthew S.; Goodson, Boyd M.; Chekmenev, Eduard Y.

2015-01-01

251

Observation of Faraday rotation from a single confined spin

information on the spin state through conditional Faraday rotation of a spectrally detuned laser, induced of the technique, we use an independent resonant laser for spin- state preparation7 . We infer that there are 10 and dispersion coexist in an optical field's response to a spectrally detuned optical transition. Although

Loss, Daniel

252

Progress towards single spin optoelectronics using quantum dot nanostructures

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

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

2005-01-01

253

Spin-dependent modes in nuclei and nuclear forces

NASA Astrophysics Data System (ADS)

Spin-dependent modes in nuclei are studied and important roles of tensor and three-body forces on nuclear structure are discussed. New shell model Hamiltonians, which have proper tensor components, are shown to explain spin properties of both stable and exotic nuclei. Gamow-Teller (GT) strengths in Ni isotopes, especially in 56Ni, are found to be well described by pf-shell Hamiltonian GXPF1J, which leads to a remarkable improvement in the evaluation of electron capture rates in stellar environmnets. GT strength in 40Ar obtained with VMU (monopole-based universal interaction) is found to be consistent with the experimental strength, and neutrino capture reaction cross sections for solar neutrinos from 8B are found to be enhanced compared with previous calculations. The repulsive monopole corrections to the microscopic two-body interactions in isospin T=1 channel are important for the proper shell evolutions in neutron-rich isotopes. The three-body force, in particular the Fujita-Miyazawa force induced by ? excitations, is pointed out to be responsible for the repulsive corrections among the valence neutrons. The important roles of the three-body force on the energies of exotic calcium isotopes as well as on the closed-shell nature of 48Ca and M1 transition in 48Ca are demonstrated.

Suzuki, Toshio; Otsuka, Takaharu; Honma, Michio

2012-10-01

254

Frequency selective detection of nuclear quadrupole resonance (NQR) spin echoes

NASA Astrophysics Data System (ADS)

Nuclear Quadrupole Resonance (NQR) is a radio frequency (RF) technique that can be used to detect the presence of quadrupolar nuclei, such as the 14N nucleus prevalent in many explosives and narcotics. The technique has been hampered by low signal-to-noise ratios and is further aggravated by the presence of RF interference (RFI). To ensure accurate detection, proposed detectors should exploit the rich form of the NQR signal. Furthermore, the detectors should also be robust to any remaining residual interference, left after suitable RFI mitigation has been employed. In this paper, we propose a new NQR data model, particularly for the realistic case where multiple pulse sequences are used to generate trains of spin echoes. Furthermore, we refine two recently proposed approximative maximum likelihood (AML) detectors, enabling the algorithm to optimally exploit the data model of the entire echo train and also incorporate knowledge of the temperature dependent spin-echo decay time. The AML-based detectors ensure accurate detection and robustness against residual RFI, even when the temperature of the sample is not precisely known, by exploiting the dependencies of the NQR resonant lines on temperature. Further robustness against residual interference is gained as the proposed detector is frequency selective; exploiting only those regions of the spectrum where the NQR signal is expected. Extensive numerical evaluations based on both simulated and measured NQR data indicate that the proposed Frequency selective Echo Train AML (FETAML) detector offers a significant improvement as compared to other existing detectors.

Somasundaram, Samuel D.; Jakobsson, Andreas; Smith, John A. S.; Althoefer, Kaspar A.

2006-05-01

255

Single-photon spin-orbit entanglement violating a Bell-like inequality

Single photons emerging from q-plates (or Pancharatnam-Berry phase optical element) exhibit entanglement in the degrees of freedom of spin and orbital angular momentum. We put forward an experimental scheme for probing the spin-orbit correlations of single photons. It is found that the Clauser-Horne-Shimony-Holt (CHSH) parameter S for the single-photon spin-orbit entangled state could be up to 2.828, evidently violating the Bell-like inequality and thus invalidating the noncontextual hidden variable (NCHV) theories.

Lixiang Chen; Weilong She

2010-01-07

256

Understanding electron and nuclear spin dynamics in Cr^5+ doped K3NbO8

NASA Astrophysics Data System (ADS)

Chromium(V) doped in the diamagnetic host potassium niobate, a simple spin S=.5ex1-.1em/ -.15em.25ex2 , I = 0 system, has been proposed as an alternative standard for field calibration and g-standard for high-field EPR [1]. This system constitutes a dilute two-level model relevant for use as a electron spin qubit [2] and as such coherent electron spin manipulation at X-band (˜9.5 GHz) was observed over a wide range temperature. Rabi oscillations are observed for the first time in a spin system based on transition metal oxides up to room temperature. At 4 K, a Rabi frequency ?R of 20 MHz together with the phase coherence relaxation (spin-spin relaxation) time, T2 of ˜10 ?s results in the single qubit figure of merit QM (=?RT2/?) as about 500, showing that a diluted ensemble of Cr(V) (S = 1/2) doped K3NbO8 is a potential candidate for solid-state quantum information processing. Also, the field and temperature dependence of the T1 (spin-lattice relaxation) and T2 times was investigated [3] for a further understanding of the relaxation mechanisms governing the phase decoherence in this system. These studies show that the coupling of the electron spin with the neighboring ^39K nuclei (I = 3/2) is one of the prominent T2 mechanisms. The hyperfine and quadrupole interactions with ^39K nuclei was resolved by using the high-frequency (240 GHz) pulsed electron nuclear double resonance (ENDOR). [3pt] [1]. B. Cage, A. Weekley, L. -C. Brunel and N. S. Dalal, Anal. Chem. 71, 1951 (1999). [0pt] [2]. S. Nellutla, K.-Y. Choi, M. Pati, J. van Tol, I. Chiroescu and N. S. Dalal, Phys. Rev. Lett. 99, 137601 (2007). [0pt] [3]. S. Nellutla, G. W. Morley, M. Pati, N. S. Dalal and J. van Tol, Phys. Rev. B. 78, 054426 (2008).

Nellutla, Saritha

2009-03-01

257

The origin of the rf magnetic-field-induced coupling between spin systems is discussed. A new nuclear-double-resonance technique employing this coupling is proposed, which has particular value in measuring pure nuclear-quadrupole-resonance spectra of integer-spin nuclei by nuclear double resonance. The sensitivity of the new technique is discussed for the case of 1H-14N double resonance in zero static magnetic field, as well as

J. Seliger; R. Blinc; M. Mali; R. Osredkar; A. Prelesnik

1975-01-01

258

Optical Manipulation of a Single Mn Spin in a CdTe-Based Quantum Dot

Two coupled CdTe quantum dots, selected from a self-assembled system, one of them containing a single Mn ion, were studied by continuous wave and modulated photoluminescence, photoluminescence excitation, and photon correlation experiments. Optical writing of information on the spin state of the Mn ion has been demonstrated, using the orientation of the Mn spin by spin-polarized carriers transferred from the

M. Goryca; T. Kazimierczuk; M. Nawrocki; A. Golnik; J. A. Gaj; P. Kossacki; P. Wojnar; G. Karczewski

2009-01-01

259

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

NASA Astrophysics Data System (ADS)

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

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

2000-08-01

260

Spin dynamics in the optical cycle of single nitrogen-vacancy centres in diamond

We investigate spin-dependent decay and intersystem crossing in the optical cycle of single negatively-charged nitrogen-vacancy (NV) centres in diamond. We use spin control and pulsed optical excitation to extract both the spin-resolved lifetimes of the excited states and the degree of optically-induced spin polarization. By optically exciting the centre with a series of picosecond pulses, we determine the spin-flip probabilities per optical cycle, as well as the spin-dependent probability for intersystem crossing. This information, together with the indepedently measured decay rate of singlet population provides a full description of spin dynamics in the optical cycle of NV centres. The temperature dependence of the singlet population decay rate provides information on the number of singlet states involved in the optical cycle.

Robledo, Lucio; van der Sar, Toeno; Hanson, Ronald

2010-01-01

261

Spin dynamics in the optical cycle of single nitrogen-vacancy centres in diamond

We investigate spin-dependent decay and intersystem crossing in the optical cycle of single negatively-charged nitrogen-vacancy (NV) centres in diamond. We use spin control and pulsed optical excitation to extract both the spin-resolved lifetimes of the excited states and the degree of optically-induced spin polarization. By optically exciting the centre with a series of picosecond pulses, we determine the spin-flip probabilities per optical cycle, as well as the spin-dependent probability for intersystem crossing. This information, together with the indepedently measured decay rate of singlet population provides a full description of spin dynamics in the optical cycle of NV centres. The temperature dependence of the singlet population decay rate provides information on the number of singlet states involved in the optical cycle.

Lucio Robledo; Hannes Bernien; Toeno van der Sar; Ronald Hanson

2010-10-06

262

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

263

All optical control of a single electron spin in diamond

Precise coherent control of the individual electronic spins associated with atom-like impurities in the solid state is essential for applications in quantum information processing and quantum metrology. We demonstrate all-optical initialization, fast coherent manipulation, and readout of the electronic spin of the negatively charged nitrogen-vacancy (NV$^-$) center in diamond at T$\\sim$7K. We then present the observation of a novel double-dark resonance in the spectroscopy of an individual NV center. These techniques open the door for new applications ranging from robust manipulation of spin states using geometric quantum gates to quantum sensing and information processing.

Yiwen Chu; Matthew Markham; Daniel J. Twitchen; Mikhail D. Lukin

2014-09-22

264

-spin detection, magnetic reso- nance force microscopy MRFM has been suggested 7Â9 as one of the most promisingRealistic simulations of single-spin nondemolition measurement by magnetic resonance force resonance force microscopy MRFM , including the effects of thermal noise and back action from monitoring. We

Goan, Hsi-Sheng

265

Simulations of a Single Spin Measurement Using Magnetic Resonance Force Microscopy

We simulated classical and quantum dynamics of a single spin measurement in magnetic resonant force microscopy (MRFM). A frequency shift of the cantilever is calculated analytically and numerically in the regime of driven oscillations of the cantilever. We study the problem: What component of the spin is measured in the cyclic adiabatic inversion MRFM? We show that a MRFM technique

Gennady Berman; Fausto Borgonovi; Vyacheslav Gorshkov; Shmuel Gurvitz; Dmitry Kamenev; Vladimir Tsifrinovich

2003-01-01

266

Ultrafast control of donor-bound electron spins with single detuned optical pulses

LETTERS Ultrafast control of donor-bound electron spins with single detuned optical pulses KAI single broadband pulses detuned from resonance in a three-level system4 . This technique is robust is based on a single pulse far detuned from the optical transition. By working off-resonance, decoherence

Loss, Daniel

267

Frequency-stepped acquisition in nuclear magnetic resonance spectroscopy under magic angle spinning

NASA Astrophysics Data System (ADS)

The nuclear magnetic resonance of paramagnetic solids is usually characterized by the presence of large chemical shifts and shift anisotropies due to hyperfine interactions. Frequently the resulting spectra cover a frequency range of several megahertz, which is greater than the bandwidth of commercially available radio-frequency (RF) probes, making it impossible to acquire the whole spectrum in a single experiment. In these cases it common to record a series of spectra, in which the probe is tuned to a different frequency for each, and then sum the results to give the "true" spectrum. While this method is very widely used on static samples, the application of frequency stepping under magic-angle spinning (MAS) is less common, owing to the increased complexity of the spin dynamics when describing the interplay of the RF irradiation with the mechanical rotation of the shift tensor. In this paper, we present a theoretical description, based on the jolting frame formalism of Caravatti et al. [J. Magn. Reson. 55, 88 (1983), 10.1016/0022-2364(83)90279-2], for describing the spin dynamics of a powder sample under MAS when subjected to a selective pulse of low RF-field amplitude. The formalism is used to describe the frequency stepping method under MAS, and under what circumstances the true spectrum is reproduced. We also present an experimental validation of the methodology under ultra-fast MAS with the paramagnetic materials LiMnPO4 and TbCsDPA.

Pell, Andrew J.; Clément, Raphaële J.; Grey, Clare P.; Emsley, Lyndon; Pintacuda, Guido

2013-03-01

268

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

269

Investigation of the Leggett-Garg Inequality for Precessing Nuclear Spins

NASA Astrophysics Data System (ADS)

We report experimental implementation of a protocol for testing the Leggett-Garg inequality (LGI) for nuclear spins precessing in an external magnetic field. The implementation involves certain controlled operations, performed in parallel on pairs of spin-1/2 nuclei (target and probe) from molecules of a nuclear magnetic resonance ensemble, which enable evaluation of temporal correlations from an LG string. Our experiment demonstrates violation of the LGI for time intervals between successive measurements, over which the effects of relaxation on the quantum state of target spin are negligible. Further, it is observed that the temporal correlations decay, and the same target spin appears to display macrorealistic behavior consistent with LGI.

Athalye, Vikram; Roy, Soumya Singha; Mahesh, T. S.

2011-09-01

270

The spin-dependent transport properties of single ferrocene, cobaltocene, and nickelocene molecules attached to the sidewall of a (4,4) armchair single-walled carbon nanotube via a Ni adatom are investigated by using a self-consistent ab initio approach that combines the non-equilibrium Green's function formalism with the spin density functional theory. Our calculations show that the Ni adatom not only binds strongly to the sidewall of the nanotube, but also maintains the spin degeneracy and affects little the transmission around the Fermi level. When the Ni adatom further binds to a metallocene molecule, its density of states is modulated by that of the molecule and electron scattering takes place in the nanotube. In particular, we find that for both cobaltocene and nickelocene the transport across the nanotube becomes spin-polarized. This demonstrates that metallocene molecules and carbon nanotubes can become a promising materials platform for applications in molecular spintronics. PMID:21721654

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

2011-06-28

271

Calculations of single-inclusive cross sections and spin asymmetries in pp scattering

We present calculations of cross sections and spin asymmetries in single-inclusive reactions in pp scattering. We discuss next-to-leading order predictions as well as all-order soft-gluon threshold resummations.

Werner Vogelsang

2005-03-03

272

Single-level resonance parameters fit nuclear cross-sections

NASA Technical Reports Server (NTRS)

Least squares analyses of experimental differential cross-section data for the U-235 nucleus have yielded single level Breit-Wigner resonance parameters that fit, simultaneously, three nuclear cross sections of capture, fission, and total.

Drawbaugh, D. W.; Gibson, G.; Miller, M.; Page, S. L.

1970-01-01

273

Single Spin Asymmetries of Identified Hadrons in Polarized p+p at p

Single Spin Asymmetries of Identified Hadrons in Polarized p+p at p s = 62.4 and 200 GeV J.H. Lee hadrons, p #6; , K #6; , p, and â?¢ p, from transversely polarized proton collisions at p s = 200 and 62 INTRODUCTION In the lowestÂorder QCD approximation, single transverse spin asymmetries (SSAs) in p " p ( â?¢ p

274

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

2007-10-25

275

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

276

Rényi information flow in the Ising model with single-spin dynamics

NASA Astrophysics Data System (ADS)

The n -index Rényi mutual information and transfer entropies for the two-dimensional kinetic Ising model with arbitrary single-spin dynamics in the thermodynamic limit are derived as functions of ensemble averages of observables and spin-flip probabilities. Cluster Monte Carlo algorithms with different dynamics from the single-spin dynamics are thus applicable to estimate the transfer entropies. By means of Monte Carlo simulations with the Wolff algorithm, we calculate the information flows in the Ising model with the Metropolis dynamics and the Glauber dynamics, respectively. We find that not only the global Rényi transfer entropy, but also the pairwise Rényi transfer entropy, peaks in the disorder phase.

Deng, Zehui; Wu, Jinshan; Guo, Wenan

2014-12-01

277

Coherent optical writing and reading of the exciton spin state in single quantum dots.

We demonstrate a one-to-one correspondence between the polarization state of a light pulse tuned to neutral exciton resonances of single semiconductor quantum dots and the spin state of the exciton that it photogenerates. This is accomplished using two variably polarized and independently tuned picosecond laser pulses. The first "writes" the spin state of the resonantly excited exciton. The second is tuned to biexcitonic resonances, and its absorption is used to "read" the exciton spin state. The absorption of the second pulse depends on its polarization relative to the exciton spin direction. Changes in the exciton spin result in corresponding changes in the intensity of the photoluminescence from the biexciton lines which we monitor, obtaining thus a one-to-one mapping between any point on the Poincaré sphere of the light polarization to a point on the Bloch sphere of the exciton spin. PMID:21405314

Benny, Y; Khatsevich, S; Kodriano, Y; Poem, E; Presman, R; Galushko, D; Petroff, P M; Gershoni, D

2011-01-28

278

Spin distribution in low-energy nuclear level schemes

The spin-cutoff parameter {sigma} has been determined for experimental spin distributions at low excitation energies of 310 nuclei between {sup 18}F and {sup 251}Cf (more than 8000 levels with their spin). The results indicate a weak dependence on the mass number A of the spin-cutoff parameter {sigma}{sup 2}{approx}A{sup 0.28}, and an even-odd spin staggering in the spin distribution of the even-even nuclei, with a strong enhancement of the number of states with spin zero. A modification of the spin-cutoff distribution formula is proposed in order to describe the even-even nuclei data. These findings are in good agreement with recent predictions of shell-model Monte Carlo calculations.

Egidy, T. von [Physik-Department, Technische Universitaet Muenchen, D-85748 Garching (Germany); Bucurescu, D. [Horia Hulubei National Institute of Physics and Nuclear Engineering, R-76900 Bucharest (Romania)

2008-11-15

279

Conditional control of donor nuclear spins in silicon using stark shifts.

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. PMID:25375741

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

2014-10-10

280

Single antidot as a passive way to create caustic spin-wave beams in yttrium iron garnet films

Single antidot as a passive way to create caustic spin-wave beams in yttrium iron garnet films R://apl.aip.org/about/rights_and_permissions #12;Single antidot as a passive way to create caustic spin-wave beams in yttrium iron garnet films R in yttrium iron garnet film. Diffraction of surface magnetostatic spin waves from such antidot

Demokritov, S.O.

281

Measurement and Control of Single Nitrogen-Vacancy Center Spins above 600 K

We study the spin and orbital dynamics of single nitrogen-vacancy (NV) centers in diamond between room temperature and 700 K. We find that the ability to optically address and coherently control single spins above room temperature is limited by nonradiative processes that quench the NV center's fluorescence-based spin readout between 550 and 700 K. Combined with electronic structure calculations, our measurements indicate that the energy difference between the 3E and 1A1 electronic states is approximately 0.8 eV. We also demonstrate that the inhomogeneous spin lifetime (T2*) is temperature independent up to at least 625 K, suggesting that single NV centers could be applied as nanoscale thermometers over a broad temperature range.

D. M. Toyli; D. J. Christle; A. Alkauskas; B. B. Buckley; C. G. Van de Walle; D. D. Awschalom

2012-01-21

282

Extraordinarily slow nuclear spin relaxation in frozen laser-polarized 129Xe

We studied the very slow nuclear spin-lattice relaxation of solid 129Xe as a function of temperature and magnetic field using laser-polarized nuclei. Relaxation times in excess of 500 h were measured. We present evidence for a new relaxation mechanism which results from a Raman spin-phonon scattering process involving the spin-rotation interaction. We also establish the existence of cross relaxation between

M. Gatzke; G. D. Cates; B. Driehuys; D. Fox; W. Happer; B. Saam

1993-01-01

283

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.

284

Infrared spectroscopy of chloromethyl radical in solid parahydrogen and its nuclear spin conversion.

We present high-resolution infrared absorption spectra of chloromethyl radical produced by in situ UV photolysis of chloroiodomethane isolated in solid parahydrogen. The radicals were stable over a few days in solid parahydrogen kept at 3.6 K. Analysis of the rotation-vibration spectra revealed that the radical exhibited quantized one-dimensional rotational motion about the C-Cl bond, while the ortho and para nuclear spin species were still clearly distinguishable in the spectra. Temporal change of the spectra indicated that the nuclear spin conversion between the ortho and para nuclear spin species of the radical in solid parahydrogen occurred in a time scale of a few hours at 3.6 K. It was also found that the nuclear spin conversion became significantly slower in a higher concentration of chloroiodomethane. PMID:23506119

Miyamoto, Yuki; Tsubouchi, Masaaki; Momose, Takamasa

2013-10-01

285

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

286

Atomic-Scale Nuclear Spin Imaging Using Quantum-Assisted Sensors in Diamond

Nuclear spin imaging at the atomic level is essential for the understanding of fundamental biological phenomena and for applications such as drug discovery. The advent of novel nanoscale sensors promises to achieve the ...

Bissbort, U.

287

A high-performance Fortran code to calculate spin- and parity-dependent nuclear level densities

NASA Astrophysics Data System (ADS)

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+g- model spaces. Examples of the calculations for 28Si (in the sd-model space) and 64Ge (in the pf+g-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+g, 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. Program summaryProgram title: MM Catalogue identifier: AENM_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AENM_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 193181 No. of bytes in distributed program, including test data, etc.: 1298585 Distribution format: tar.gz Programming language: Fortran 90, MPI. Computer: Any architecture with a Fortran 90 compiler and MPI. Operating system: Linux. RAM: Proportional to the system size, in our examples, up to 75Mb Classification: 17.15. External routines: MPICH2 (http://www.mcs.anl.gov/research/projects/mpich2/) Nature of problem: Calculating of the spin- and parity-dependent nuclear level density. Solution method: The algorithm implies exact calculation of the first and second Hamiltonian moments for different configurations at fixed spin and parity. The code is parallelized using the Message Passing Interface and a master-slaves dynamical load-balancing approach. Restrictions: The program uses two-body interaction in a restricted single-level basis. For example, GXPF1A in the pf-valence space. Running time: Depends on the system size and the number of processors used (from 1 min to several hours).

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

2013-01-01

288

The determination of the in situ structure by nuclear spin contrast variation

Polarized neutron scattering from polarized nuclear spins in hydrogenous substances opens a new way of contrast variation. The enhanced contrast due to proton spin polarization was used for the in situ structure determination of tRNA of the functional complex of the E.coli ribosome.

Stuhrmann, H.B. [GKSS Forschungszentrum, Geesthacht (Germany); Nierhaus, K.H. [Max-Planch-Institut fuer Molekulare Genetik, Berlin (Germany)

1994-12-31

289

Transverse Relaxation of Cu Nuclear Spins in YBa2Cu3O6.98

We have measured the transverse relaxation of the planar Cu(2) nuclear spins in an oriented powder sample of YBa2Cu3O6.98 (Tc{=}92 K) by using the nuclear quadrupole resonance (NQR) technique. Above Tc, after subtraction of the Tl process, the spin echo envelope decay follows a Gaussian form, and its time constant is almost independent of temperature. In the vicinity of Tc,

Yutaka Itoh; Hiroshi Yasuoka; Yutaka Ueda

1990-01-01

290

Multi-scales nuclear spin relaxation of liquids in porous media

The magnetic field dependence of the nuclear spin–lattice relaxation rate 1\\/T1(?0) is a rich source of dynamical information for characterizing the molecular dynamics of liquids in confined environments. Varying the magnetic field changes the Larmor frequency ?0, and thus the fluctuations to which the nuclear spin relaxation is sensitive. Moreover, this method permits a more complete characterization of the dynamics

Jean-Pierre Korb

2010-01-01

291

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

292

We describe the optical resonant manipulation of a single magnetic impurity in a self-assembled quantum dot. We show that using the resonant pumping one can address and manipulate selectively individual spin states of a magnetic impurity. The mechanisms of resonant optical polarization of a single impurity in a quantum dot involve anisotropic exchange interactions and are different than those in

Alexander O. Govorov; Alexander V. Kalameitsev

2005-01-01

293

Modified approach to single-spin detection using magnetic resonance force microscopy

The magnetic moment of a single spin interacting with a cantilever in magnetic resonance force microscopy (MRFM) experiences quantum jumps in orientation rather than smooth oscillations. These jumps cannot be detected by a conventional MRFM based on observation of driven resonant oscillations of a cantilever. In this paper, we propose a method which should allow detection of the magnetic signal from a single spin using a modification of a conventional MRFM. We estimate the opportunity to detect the magnetic signal from a single proton. (c) 2000 The American Physical Society.

Berman, Gennady P. [Theoretical Division, T-13, MS B213, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division, T-13, MS B213, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Tsifrinovich, Vladimir I. [IDS Department, Polytechnic University, Six Metrotech Center, Brooklyn, New York 11201 (United States)] [IDS Department, Polytechnic University, Six Metrotech Center, Brooklyn, New York 11201 (United States)

2000-02-01

294

We propose a teleportation scheme that relies only on single-photon measurements and Faraday rotation, for teleportation of many-qubit entangled states stored in the electron spins of a quantum dot system. The interaction between a photon and the two electron spins, via Faraday rotation in microcavities, establishes Greenberger-Horne-Zeilinger entanglement in the spin-photon-spin system. The appropriate single-qubit measurements, and the communication of

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

2005-01-01

295

We propose a teleportation scheme that relies only on single-photon measurements and Faraday rotation, for teleportation of many-qubit entangled states stored in the electron spins of a quantum dot system. The interaction between a photon and the two electron spins, via Faraday rotation in micro- cavities, establishes Greenberger-Horne-Zeilinger entanglement in the spin-photon-spin system. The appropriate single-qubit measurements, and the communication

Michael N. Leuenberger; Michael E. Flatte; D. D. Awschalom

2005-01-01

296

In the generalized matrix ENDOR line shape model (P.A. Narayana et al., J. Chem. Phys., 67, 1990 (1977)) the ENDOR intensity is controlled by the nuclear spin lattice relaxation rate formulated as an angularly dependent electron-nuclear dipolar contribution and an angularly independent intrinsic bulk nuclear relaxation contribution. Comparison of this model with single crystal data (L. Kevan et al., J. Chem. Phys., 70, 5006 (1979)) showed that the angularly independent relaxation rate must be more rapid than the intrinsic bulk nuclear relaxation rate. Here we identify the angularly independent relaxation rate with nuclear spin diffusion and apply this interpretation quantitatively to data on methyl radicals in lithium acetate dihydrate crystals and to the radiation generated CH/sub 3/CH(NH/sub 3/)COOH/sup -/ radical in alanine at 77 K.

Schlick, S.; Kevan, L.; Toriyama, K.; Iwasaki, M.

1981-01-01

297

NASA Astrophysics Data System (ADS)

Methods of the diagnostics of the spatial spin-modulated structure of the cycloidal type in multiferroics based on nuclear magnetic resonance and Mössbauer spectroscopy have been considered. It has been established that Mössbauer spectroscopy makes it possible to determine the anharmonicity parameter of the spatial spin-modulated structure of the cycloidal type with no worse accuracy than nuclear magnetic resonance with higher resolution. Mössbauer spectroscopy, being sensitive to the hyperfine quadrupole interaction of the nucleus in the excited state, makes it possible to obtain additional information on the features of the spatial spin-modulated structure.

Rusakov, V. S.; Pokatilov, V. S.; Sigov, A. S.; Matsnev, M. E.; Gubaidulina, T. V.

2014-12-01

298

Excited-state spectroscopy using single-spin manipulation in diamond

We use single-spin resonant spectroscopy to study the spin structure in the orbital excited-state of a diamond nitrogen-vacancy center at room temperature. We find that the excited state spin levels have a zero-field splitting that is approximately half of the value of the ground state levels, a g-factor similar to the ground state value, and a hyperfine splitting ~20x larger than in the ground state. In addition, the width of the resonances reflects the electronic lifetime in the excited state. We also show that the spin-splitting can significantly differ between NV centers, likely due to the effects of local strain, which provides a pathway to control over the spin Hamiltonian and may be useful for quantum information processing.

G. D. Fuchs; V. V. Dobrovitski; R. Hanson; A. Batra; C. D. Weis; T. Schenkel; D. D. Awschalom

2008-06-11

299

Optical manipulation of a single Mn spin in a CdTe-based quantum dot.

Two coupled CdTe quantum dots, selected from a self-assembled system, one of them containing a single Mn ion, were studied by continuous wave and modulated photoluminescence, photoluminescence excitation, and photon correlation experiments. Optical writing of information on the spin state of the Mn ion has been demonstrated, using the orientation of the Mn spin by spin-polarized carriers transferred from the neighboring quantum dot. Mn spin orientation time values from 20 to 100 ns were measured, depending on the excitation power. Storage time of the information on the Mn spin was found to be enhanced by application of a static magnetic field of 1 T, reaching hundreds of microseconds in the dark. Simple rate equation models were found to describe correctly the static and dynamical properties of the system. PMID:19792759

Goryca, M; Kazimierczuk, T; Nawrocki, M; Golnik, A; Gaj, J A; Kossacki, P; Wojnar, P; Karczewski, G

2009-08-21

300

Spin-dependent electron transport in protein-like single-helical molecules.

We report on a theoretical study of spin-dependent electron transport through single-helical molecules connected by two nonmagnetic electrodes, and explain the experiment of significant spin-selective phenomenon observed in ?-helical protein and the contradictory results between the protein and single-stranded DNA. Our results reveal that the ?-helical protein is an efficient spin filter and the spin polarization is robust against the disorder. These results are in excellent agreement with recent experiments [Mishra D, et al. (2013) Proc Natl Acad Sci USA 110(37):14872-14876; Göhler B, et al. (2011) Science 331(6019):894-897] and may facilitate engineering of chiral-based spintronic devices. PMID:25071198

Guo, Ai-Min; Sun, Qing-Feng

2014-08-12

301

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

302

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

303

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

304

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

305

NASA Astrophysics Data System (ADS)

Dynamical magnetic and nuclear polarization in complex spin systems is discussed on the example of transfer of spin from exciton to the central spin of magnetic impurity in a quantum dot in the presence of a finite number of nuclear spins. The exciton is described in terms of electron and heavy-hole spins interacting via exchange interaction with magnetic impurity, via hyperfine interaction with a finite number of nuclear spins and via dipole interaction with photons. The time evolution of the exciton, magnetic impurity and nuclear spins is calculated exactly between quantum jumps corresponding to exciton radiative recombination. The collapse of the wavefunction and the refilling of the quantum dot with a new spin-polarized exciton is shown to lead to the build up of magnetization of the magnetic impurity as well as nuclear spin polarization. The competition between electron spin transfer to magnetic impurity and to nuclear spins simultaneous with the creation of dark excitons is elucidated. The technique presented here opens up the possibility of studying optically induced dynamical magnetic and nuclear polarization in complex spin systems.

Abolfath, Ramin M.; Trojnar, Anna; Roostaei, Bahman; Brabec, Thomas; Hawrylak, Pawel

2013-06-01

306

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

NASA Astrophysics Data System (ADS)

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

Simmons, Christie

2012-02-01

307

Charge and spin readout scheme for single self-assembled quantum dots

NASA Astrophysics Data System (ADS)

We propose an all optical spin initialization and readout concept for single self-assembled quantum dots, and demonstrate its feasibility. Our approach is based on a gateable single dot photodiode structure that can be switched between charge and readout modes. After optical electron generation and storage, we propose to employ a spin-conditional absorption of a circularly polarized light pulse tuned to the single negatively charged exciton transition to convert the spin information of the resident electron to charge occupancy. Switching the device to the charge readout mode then allows us to probe the charge state of the quantum dot (1e,2e) using nonresonant luminescence. The spin orientation of the resident electron is then reflected by the photoluminescence (PL) yield of doubly (X2-) and singly (X-1) charged transitions in the quantum dot. To verify the feasibility of this spin readout concept, we have applied time gated photoluminescence to confirm that selective optical charging and efficient nonperturbative measurement of the charge state can be performed on the same dot. The results show that, by switching the electric field in the vicinity of the quantum dot, the charging rate can be switched between a regime of efficient electron generation (??106s-1W-1cm2) and a readout regime, where the charge occupancy and, therefore, the spin state of the dot can be tested via PL over millisecond timescales, without altering it. Our results show that such a quasicontinuous, nonperturbative readout of the charge state of the dot allows increasing the dark time available for undisturbed spin manipulation and storage into the millisecond range, while still providing sufficient signal for high fidelity readout. Consequently, our readout scheme would allow the investigation of spin relaxation and decoherence mechanisms over the long timescales, predicted by theory.

Heiss, D.; Jovanov, V.; Bichler, M.; Abstreiter, G.; Finley, J. J.

2008-06-01

308

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

309

Back-action-driven electron spin excitation in a single quantum dot

NASA Astrophysics Data System (ADS)

We perform real-time charge counting with a quantum point contact (QPC) for the last six electrons in a single quantum dot. At zero magnetic field, the charge-counting statistics show distinctive non-thermal-equilibrium effects for the even and odd electron numbers. A detailed study relates this difference to the excitation from the spin singlet state to triplet states driven by QPC back-action. At a finite magnetic field, spin excitations to different triplet states and Zeeman states are also observed. A master-equation model is developed to quantitatively characterize the back-action-driven spin excitation rate.

Cao, Gang; Xiao, Ming; Li, HaiOu; Zhou, Cheng; Shang, RuNan; Tu, Tao; Jiang, HongWen; Guo, GuoPing

2013-02-01

310

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

311

Spin-polarized transport through single-molecule magnet Mn6 complexes

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

312

Ultrafast control of donor-bound electron spins with single detuned optical pulses

The ability to control spins in semiconductors is important in a variety of fields including spintronics and quantum information processing. Due to the potentially fast dephasing times of spins in the solid state [1-3], spin control operating on the picosecond or faster timescale may be necessary. Such speeds, which are not possible to attain with standard electron spin resonance (ESR) techniques based on microwave sources, can be attained with broadband optical pulses. One promising ultrafast technique utilizes single broadband pulses detuned from resonance in a three-level Lambda system [4]. This attractive technique is robust against optical pulse imperfections and does not require a fixed optical reference phase. Here we demonstrate the principle of coherent manipulation of spins theoretically and experimentally. Using this technique, donor-bound electron spin rotations with single-pulse areas exceeding pi/4 and two-pulses areas exceeding pi/2 are demonstrated. We believe the maximum pulse areas attained do not reflect a fundamental limit of the technique and larger pulse areas could be achieved in other material systems. This technique has applications from basic solid-state ESR spectroscopy to arbitrary single-qubit rotations [4, 5] and bang-bang control[6] for quantum computation.

Kai-Mei C. Fu; Susan M. Clark; Charles Santori; M. C. Holland; Colin R. Stanley; Yoshihisa Yamamoto

2008-06-25

313

using SWAP operations3,6,18 , or incoherently using a family of dynamic nuclear 1Department of Materials nuclear spins using photoexcited triplet states Vasileia Filidou1 , Stephanie Simmons1 , Steven D. Karlen11,2 . Although nuclear spins are advantageous as quantum bits (qubits) because of their long

Loss, Daniel

314

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

315

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

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

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

2014-01-01

316

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

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

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

2014-01-01

317

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

318

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

319

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

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

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

2015-01-01

320

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

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

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

2015-01-01

321

We address a problem of generating a robust entangling gate between electronic and nuclear spins in the system of a single nitrogen-vacany centre coupled to a nearest Carbon-13 atom in diamond against certain types of systematic errors such as pulse-length and off-resonance errors. We analyse the robustness of various control schemes: sequential pulses, composite pulses and numerically-optimised pulses. We find that numerically-optimised pulses, produced by the gradient ascent pulse engineering algorithm (GRAPE), are more robust than the composite pulses and the sequential pulses. The optimised pulses can also be implemented in a faster time than the composite pulses.

Said, R S

2009-01-01

322

We address a problem of generating a robust entangling gate between electronic and nuclear spins in the system of a single nitrogen-vacany centre coupled to a nearest Carbon-13 atom in diamond against certain types of systematic errors such as pulse-length and off-resonance errors. We analyse the robustness of various control schemes: sequential pulses, composite pulses and numerically-optimised pulses. We find that numerically-optimised pulses, produced by the gradient ascent pulse engineering algorithm (GRAPE), are more robust than the composite pulses and the sequential pulses. The optimised pulses can also be implemented in a faster time than the composite pulses.

R. S. Said; J. Twamley

2009-03-23

323

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

Tosi, Guilherme, E-mail: g.tosi@unsw.edu.au; Mohiyaddin, Fahd A.; Morello, Andrea, E-mail: a.morello@unsw.edu.au [Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia. (Australia); Huebl, Hans [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching (Germany); Nanosystems Initiative Munich (NIM), Schellingstr. 4, D-80799 Munich, Germany. (Germany)

2014-08-15

324

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

325

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

326

ELECTRON SPIN RESONANCE OF IRRADIATED SINGLE CRYSTALS OF L-PHENYLALANINE-HCL*

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

Fasanella, Edwin L.; Gordy, Walter

1969-01-01

327

Study of Nuclear Bound States Using Mean-Field Woods-Saxon and Spin-Orbit Potentials

NASA Astrophysics Data System (ADS)

The neutron single-particle bound states as solutions of radial Schrödinger equation for the central Woods-Saxon potential together with spin-orbit interaction and centrifugal terms have been obtained analytically. By introducing new variable and using Taylor expansion, the differential equation has been transformed to solvable hypergeometric type. This differential equation has also been solved using Nikiforov-Uvarov (NU) method. Neutron single-particle states have been derived as self-adjoint form of hypergeometric series. By means of boundary conditions, which implies eigenvalue condition as complicated relation between energy eigenvalues and parameters of nuclear potential, the neutron single-particle energy eigenvalues have been derived using graphical method. To examine method, numerical results in special cases of S states are evaluated. Results obtained using this method are in satisfactory agreements with available numerical solutions.

Pahlavani, M. R.; Alavi, S. A.

2012-09-01

328

Single transverse-spin asymmetry in Drell-Yan production at large and moderate transverse momentum

We study the single-transverse-spin asymmetry for the Drell-Yan process. We consider production of the lepton pair at large transverse momentum, q{sub perpendicular}{approx}Q, where Q is the pair's mass. The spin asymmetry is then of higher twist and may be generated by twist-three quark-gluon correlation functions. Expanding the result for q{sub perpendicular}<single-transverse-spin asymmetries.

Ji Xiangdong [Physics Department, University of Maryland, College Park, Maryland 20742 (United States); Qiu Jianwei [Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); Vogelsang, Werner [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); RIKEN BNL Research Center, Building 510A, Brookhaven National Laboratory, Upton, New York 11973 (United States); Yuan Feng [RIKEN BNL Research Center, Building 510A, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2006-05-01

329

Shot Noise as a Probe of Spin-Polarized Transport through Single Atoms

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

330

Hahn-echo decay for exchange-coupled nuclear spins in solids.

In this paper we present a simple model to calculate the Hahn-echo decay of the exchange-coupled nuclear spins in solids. Satisfactory agreement between the calculated and experimentally observed echo decay of the exchange-coupled spins of T203l and T205l isotopes in thallium chloride TlCl and thallium tantalum sulfide TlTaS(3) is obtained. PMID:22463816

Sergeev, N A; Panich, A M

2012-01-01

331

The magnetic properties of the spin-1 Heisenberg antiferromagnetic chain with single-ion anisotropy

NASA Astrophysics Data System (ADS)

The magnetic properties of the spin-1 Heisenberg antiferromagnetic chain with exchange anisotropy and single-ion anisotropy are studied by the double-time Green's function method. The determinative equations for the critical temperature, the magnetization, and the zero-field susceptibility are derived analytically. The effects of the anisotropies on the magnetic properties are presented.

Hu, Gangsan; Zhu, Rengui

2015-02-01

332

Broadband excitation by chirped pulses: application to single electron spins in diamond

.4. Multi-line broadband spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4. Conclusions 13Broadband excitation by chirped pulses: application to single electron spins in diamond I Niemeyer1 are used. If the corresponding high power is not available or not desirable, the pulses can be replaced

Suter, Dieter

333

Single-spin measurement and decoherence in magnetic-resonance force microscopy G. P. Berman,1

Single-spin measurement and decoherence in magnetic-resonance force microscopy G. P. Berman,1 F inversion CAI technique in magnetic-resonance force microscopy MRFM . We study the problem: What component.67.Lx I. INTRODUCTION Magnetic-resonance force microscopy MRFM is striv- ing for its ultimate goal

Goan, Hsi-Sheng

334

A requirement for many quantum computation schemes is the ability to measure single spins. This paper examines one proposed scheme: magnetic resonance force microscopy, including the effects of thermal noise and back-action from monitoring. We derive a simplified equation using the adiabatic approximation, and produce a stochastic pure state unraveling which is useful for numerical simulations.

Brun, T A; Brun, Todd A.; Goan, Hsi-Sheng

2003-01-01

335

A requirement for many quantum computation schemes is the ability to measure single spins. This paper examines one proposed scheme: magnetic resonance force microscopy, including the effects of thermal noise and back-action from monitoring. We derive a simplified equation using the adiabatic approximation, and produce a stochastic pure state unraveling which is useful for numerical simulations.

Todd A. Brun; Hsi-Sheng Goan

2003-02-25

336

The Completion of Single-Spin Asymmetry Measurements at the Proza Setup

Single spin asymmetry in inclusive $\\pi^0$-production was measured in the polarized target fragmentation region using 50 GeV proton beam. The asymmetry is in agreement with asymmetry measurements in the polarized beam fragmentation region carried out at higher energies. The measurement completed 30-years history of polarized measurements at the PROZA setup.

V. V. Mochalov; A. N. Vasiliev; N. A. Bazhanov; N. I. Belikov; A. A. Belyaev; N. S. Borisov; A. M. Davidenko; A. A. Derevschikov; V. N. Grishin; A. B. Lazarev; A. A. Lukhanin; Yu. A. Matulenko; Yu. M. Melnik; A. P. Meschanin; N. G. Minaev; D. A. Morozov; A. B. Neganov; L. V. Nogach; S. B. Nurushev; Yu. A. Plis; A. F. Prudkoglyad; P. A. Semenov; L. F. Soloviev; O. N. Shchevelev; Yu. A. Usov; A. E. Yakutin

2009-12-27

337

Modified approach to single-spin detection using magnetic resonance force microscopy

The magnetic moment of a single spin interacting with a cantilever in magnetic resonance force microscopy (MRFM) experiences quantum jumps in orientation rather than smooth oscillations. These jumps cannot be detected by a conventional MRFM based on observation of driven resonant oscillations of a cantilever. In this paper, we propose a method which should allow detection of the magnetic signal

Gennady P. Berman; Vladimir I. Tsifrinovich

2000-01-01

338

Nuclear-Spin Selection Rules in the Chemistry of Interstellar Nitrogen Hydrides

NASA Astrophysics Data System (ADS)

Nitrogen hydrides are at the root of the nitrogen chemistry in interstellar space. The detailed modeling of their gas phase formation, however, requires the knowledge of nuclear-spin branching ratios for chemical reactions involving multiprotonated species. We investigate in this work the nuclear-spin selection rules in both exothermic and near thermoneutral ion-molecule reactions involved in the synthesis of ammonia, assuming full scrambling of protons in the reaction complexes. The formalism of Oka [ J. Mol. Spectrosc. 2004, 228, 635 ] is employed for highly exothermic ion-molecule and dissociative recombination reactions. For thermoneutral reactions, a simple state-to-state statistical approach is suggested, which is in qualitative agreement with both quantum scattering and microcanonical statistical calculations. This model is applied to the seven atom reaction NH4+ + H2, of possible importance in the nuclear-spin thermalization of ammonia.

Rist, Claire; Faure, Alexandre; Hily-Blant, Pierre; Le Gal, Romane

2013-10-01

339

Nuclear-spin selection rules in the chemistry of interstellar nitrogen hydrides.

Nitrogen hydrides are at the root of the nitrogen chemistry in interstellar space. The detailed modeling of their gas phase formation, however, requires the knowledge of nuclear-spin branching ratios for chemical reactions involving multiprotonated species. We investigate in this work the nuclear-spin selection rules in both exothermic and near thermoneutral ion–molecule reactions involved in the synthesis of ammonia, assuming full scrambling of protons in the reaction complexes. The formalism of Oka [ J. Mol. Spectrosc. 2004, 228, 635] is employed for highly exothermic ion–molecule and dissociative recombination reactions. For thermoneutral reactions, a simple state-to-state statistical approach is suggested, which is in qualitative agreement with both quantum scattering and microcanonical statistical calculations. This model is applied to the seven atom reaction NH4(+) + H2, of possible importance in the nuclear-spin thermalization of ammonia. PMID:23461639

Rist, Claire; Faure, Alexandre; Hily-Blant, Pierre; Le Gal, Romane

2013-10-01

340

We report solid state {sup 13}C and {sup 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, {sup 1}H and cross-polarized {sup 13}C NMR signals from {sup 15}N,{sup 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 T{sub 1e} 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., E-mail: thurberk@niddk.nih.gov; Tycko, Robert [Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520 (United States)] [Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520 (United States)

2014-05-14

341

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

342

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

2009-08-12

343

NASA Astrophysics Data System (ADS)

The use of topological phases for the manipulation of electron spins in GaAs quantum dots is a promising candidate for solid state quantum computation and non-charged based logic devices for projected post-CMOS technology. A single electron can be trapped and its spin can be manipulated by moving the quantum dot adiabatically in a closed loop (Berry effect) through the application of gate potentials. In this paper, we present numerical simulations and analytical expressions for the transition probability of electron spins in single electron devices for a quantum dot. Using analytical and numerical techniques, we calculate the Berry Phase for both nondegenerate and degenerate cases. We show that the spin orbit coupling in III-V type semiconductors will enhance the transition probability of the electron spin over pure Dresselhaus or pure Rashba cases considered separately. Considering these mechanisms separately however, is useful in that an exact solution exists as determined by the Feynman disentangling technique. For the most general cases where the solution of the propagator becomes non-trivial, we carry out the numerical simulations of such propagator.

Prabhakar, Sanjay; Raynolds, James E.; Inomata, Akira

2010-04-01

344

The phase of a superposition state is a quintessential characteristic that differentiates a quantum bit of information from a classical one. This phase can be manipulated dynamically or geometrically, and can be exploited to sensitively estimate Hamiltonian parameters, perform faithful quantum state tomography and encode quantum information into multiple modes of an ensemble. Here we discuss the methods that we have employed to manipulate and exploit the phase information of single-, two-, multi-qubit and multi-mode spin systems. PMID:22946041

Simmons, Stephanie; Wu, Hua; Morton, John J L

2012-10-13

345

There has been much recent interest in extending the technique of magnetic resonance imaging (MRI) down to the level of single spins with sub-optical wavelength resolution. However, the signal to noise ratio for images of individual spins is usually low and this necessitates long acquisition times and low temperatures to achieve high resolution. An exception to this is the nitrogen-vacancy (NV) color center in diamond whose spin state can be detected optically at room temperature. Here we apply MRI to magnetically equivalent NV spins in order to resolve them with resolution well below the optical wavelength of the readout light. In addition, using a microwave version of MRI we achieved a resolution that is 1/270 size of the coplanar striplines, which define the effective wavelength of the microwaves that were used to excite the transition. This technique can eventually be extended to imaging of large numbers of NVs in a confocal spot and possibly to image nearby dark spins via their mutual magnetic interaction with the NV spin.

Chang Shin; Changdong Kim; Roman Kolesov; Gopalakrishnan Balasubramanian; Fedor Jelezko; Jörg Wrachtrup; Philip R. Hemmer

2010-03-29

346

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

347

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

348

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

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

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

2007-01-01

349

Spin-filtering transport and switching effect of MnCu single-molecule magnet

NASA Astrophysics Data System (ADS)

Electron transport of a single-molecule magnet (SMM) device has been investigated using the first-principles calculations. The SMM based device is constructed by a SMM MnCu [MnCuCl(5-Br-sap)2(MeOH)] bridged between semi-infinite Au(100) electrodes with thiol groups connecting the molecule and the gold electrodes. Our results exhibit crucial features of spin filtering and Kondo resonance. The spin filtering remains robust, whereas the Kondo resonance highly depends on the contact geometry. Specifically, this Kondo resonance can be switched on or off by changing the contact distance. The mechanisms of these features are formulated in details.

Hao, H.; Zheng, X. H.; Dai, Z. X.; Zeng, Z.

2010-05-01

350

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

We study the transverse single spin asymmetry in Drell-Yan production in pA collisions with incoming protons being transversely polarized. We carry out the calculation using a newly developed hybrid approach. The polarized cross section computed in the hybrid approach is consistent with that obtained from the usual TMD factorization at low transverse momentum as expected, whereas at high transverse momentum, color entanglement effect is found to play a role in contributing to the spin asymmetry of Drell-Yan production, though it is a $1/N_c^2$ suppressed effect.

Zhou, Jian

2015-01-01

351

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

NASA Astrophysics Data System (ADS)

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

Schäfer, Andreas; Zhou, Jian

2014-08-01

352

Electron-Hole Asymmetry of Spin Injection and Transport in Single-Layer Graphene

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

353

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

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

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

2009-04-01

354

Transverse Relaxation of Cu Nuclear Spins in YBa2Cu3O6.98

NASA Astrophysics Data System (ADS)

We have measured the transverse relaxation of the planar Cu(2) nuclear spins in an oriented powder sample of YBa2Cu3O6.98 (Tc{=}92 K) by using the nuclear quadrupole resonance (NQR) technique. Above Tc, after subtraction of the Tl process, the spin echo envelope decay follows a Gaussian form, and its time constant is almost independent of temperature. In the vicinity of Tc, however, the Gaussian line shape is gradually narrowed. The calculated value (TG{=}149 ?sec) for the Gaussian time constant based on the direct nuclear dipole-dipole interaction is comparable to the experimental one (TG{=}131± 2 ?sec) at 297 K. Hence, the nuclear indirect coupling proposed previously may not be needed. Below Tc, the Gaussian line shape was found to be narrowed depending on Hl, and especially, it is sharply narrowed at 35 K and 87 K.

Itoh, Yutaka; Yasuoka, Hiroshi; Ueda, Yutaka

1990-10-01

355

The properties of spin polarized pure neutron matter and symmetric nuclear matter are studied using the finite range simple effective interaction, upon its parametrization revisited. Out of the total twelve parameters involved, we now determine ten of them from nuclear matter, against the nine parameters in our earlier calculation, as required in order to have predictions in both spin polarized nuclear matter and finite nuclei in unique manner being free from uncertainty found using the earlier parametrization. The information on the effective mass splitting in polarized neutron matter of the microscopic calculations is used to constrain the one more parameter, that was earlier determined from finite nucleus, and in doing so the quality of the description of finite nuclei is not compromised. The interaction with the new set of parameters is used to study the possibilities of ferromagnetic and antiferromagnetic transitions in completely polarized symmetric nuclear matter. Emphasis is given to analyze the resul...

Behera, B; Routray, T R; Centelles, M

2015-01-01

356

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 (B(1S)) 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 4mm diameter sapphire rotor containing the sample. The predicted average B(1S) field is 13?T/W(1/2), where S denotes the electron spin. For a routinely achievable input power of 5W the corresponding value is ?(S)B(1S)=0.84MHz. 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 (13)C-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, Björn; Griffin, Robert G; Temkin, Richard J

2011-05-01

357

Realization of quantum non-demolition measurement of nuclear spin 1\\/2 of cold ytterbium atom

We have demonstrated a quantum non-demolition (QND) measurement with a collective spin of cold ytterbium atoms (171Yb) via Faraday rotation interaction, and have observed 1.8-1.5+2.4 dB spin squeezing. Since 171Yb atoms have only a nuclear spin of one-half in the ground state, the system constitutes the simplest spin ensemble and is thus robust against decoherence. Furthermore, we have considered the

T. Takano; R. Namiki; Y. Takahashi

2009-01-01

358

Coherent storage of microwave excitations in rare-earth nuclear spins

Interfacing between various elements of a computer - from memory to processors to long range communication - will be as critical for quantum computers as it is for classical computers today. Paramagnetic rare earth doped crystals, such as Nd$^{3+}$:Y$_2$SiO$_5$ (YSO), are excellent candidates for such a quantum interface: they are known to exhibit long optical coherence lifetimes (for communication via optical photons), possess a nuclear spin (memory) and have in addition an electron spin that can offer hybrid coupling with superconducting qubits (processing). Here we study two of these three elements, demonstrating coherent storage and retrieval between electron and $^{145}$Nd nuclear spin states in Nd$^{3+}$:YSO. We find nuclear spin coherence times can reach 9 ms at $\\approx 5$ K, about two orders of magnitude longer than the electron spin coherence, while quantum state and process tomography of the storage/retrieval operation reveal an average state fidelity of 0.86. The times and fidelities are expected to further improve at lower temperatures and with more homogeneous radio-frequency excitation.

Gary Wolfowicz; Hannes Maier-Flaig; Robert Marino; Alban Ferrier; Hervé Vezin; John J. L. Morton; Philippe Goldner

2014-12-23

359

Korringa-Like Nuclear Spin-Lattice Relaxation in a 2DES at ?= 1/2

NASA Astrophysics Data System (ADS)

Via a resistively-detected NMR technique, the nuclear spin lattice relaxation time T1 of ^71Ga at low temperatures has been measured in a GaAs/AlGaAs heterostructure containing two weakly-coupled 2D electron systems (2DES), each at Landau level filling ?= 1/2. Incomplete electronic spin polarization, which has been reported previously [1,2] for low density 2DESs at ?= 1/2, should facilitate hyperfine- coupled nuclear spin relaxation owing to the presence of both electron spin states at the Fermi level. Within composite fermion theory, a Korringa law temperature dependence: T1T = constant, is expected for temperatures T<1 K. Our measurements made at temperatures in the range 35 mK

Tracy, L. A.; Pfeiffer, L. N.

2005-03-01

360

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

361

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

362

NASA Astrophysics Data System (ADS)

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

Koirala, Suman; Kuhn, Sebastian

2013-04-01

363

NASA Astrophysics Data System (ADS)

We study the effect of Coulomb interactions on the low-energy band structure of single-layer transition metal dichalcogenide semiconductors using an effective low-energy model. We show how a large conduction band spin splitting and a spin dependent Fermi velocity are generated in MoS2, as a consequence of the difference between the gaps of the two spin projections induced by the spin-orbit interaction. The conduction band and Fermi velocity spin splitting found are in agreement with the optical absorption energies of the excitonic peaks A, B measured in the experiments.

Ferreiros, Yago; Cortijo, Alberto

2014-11-01

364

The nuclear spin-isospin response to quasifree nucleon scattering

The Neutron-Time-of-Flight (NTOF) facility at LAMPF has been used to measure complete sets of polarization-transfer coefficients for quasifree ({rvec p},{rvec n}) scattering from {sup 2}H, {sup 12}C, and {sup 40}Ca at 494 MeV and scattering angles of 12.5{degrees}, 18{degrees}, and 27{degrees} (q = 1.2, 1.7, 2.5 fm{sup {minus}1}). These measurements yield separated transverse ({sigma} {times} q) and longitudinal ({sigma}{center_dot}q) isovector spin responses. Comparison of the separated responses to calculations and to electron-scattering responses reveals a strong enhancement in the spin transverse channel. This excess transverse strength masks the effect of pionic correlations in the response ratio.

Taddeucci, T.N.

1995-12-31

365

Self-consistent mean-field theory of the XXZ ferrimagnetic spin chain with single-ion anisotropy

NASA Astrophysics Data System (ADS)

The extended self-consistent mean-field theory is applied to study the XXZ ferrimagnetic spin chain with single-ion anisotropy. Based on the effects of XXZ anisotropy ? and single-ion anisotropy D, we calculate the energy excitation spectrums, energy gaps, static uniform susceptibility and specific heat. The magnetization plateau of ferrimagnetic spin chain with single-ion anisotropy D disappears at the critical point Dc = 1.335.

Li, Yinxiang; Chen, Bin; Zhang, Zhengfan; Han, Rushan

2015-01-01

366

Nuclear Spin Relaxation Characteristic of Submonolayer He Films in Nanochannels

NASA Astrophysics Data System (ADS)

In order to obtain information on dynamics of helium films in the nondegenerate fluid region, we have performed a pulsed-NMR experiment at 3.29 MHz on He films adsorbed in straight 2.4 nm channels of FSM silicates down to 0.54 K. In general, the spin-lattice and spin-spin relaxation times and were explained in terms of the two-dimensional Bloembergen-Purcell-Pound model for dipolar relaxation. Temperature dependences of in submonolayer He films show a minimum, indicating that the dipolar-field correlation time is about s. The temperature of the minimum monotonically lowers with increasing coverage, suggesting that He adatoms become more mobile at higher coverages. The low-dimensional property of He adatoms is observed as the separation of and above where . On the other hand, several features specific to films in the nanochannel geometry were also found. Especially, the temperature dependence of becomes very small just below and shows a shoulder at lower temperatures. This anomaly has not been observed in He adsorbed in wider pores or on flat surfaces, so that it is considered to be characteristic of He films confined in narrow channels with a diameter of a few nm.

Matsushita, Taku; Kawai, Ryosuke; Kuze, Atsushi; Hieda, Mitsunori; Wada, Nobuo

2014-04-01

367

Two free radicals are identified by electron spin resonance--electron nuclear double resonance (ESR-ENDOR) spectroscopy in single crystals of guanosine 3',5'-cyclic monophosphate x irradiated at 4.2 K. The two absorptions are attributed to the anion and cation formed on the guanine moiety. The characteristics of the cation absorption are consistent with those postulated previously for guanine cation presumed to form in irradiated DNA.

Kim, H.; Budzinski, E.E.; Box, H.C.

1989-02-01

368

RESONANCE RELAXAT/ON DANS LES ISOLANTS NUCLEAR RELAXATION, SPIN ECHO

of the nuclear echo signal (hl)was observed, when microwave pulse with the power more than spin-wave threshold was applied at any time between the first radio pulse and the signal echo (Fig. 1). If the pair of 900 radio-pulse. Such behaviour of the echo signal intensity can be explaned supposing existenceof

Boyer, Edmond

369

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

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

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

2010-07-02

370

Nonergodic nuclear depolarization in nanocavities

Recently, it has been observed that the effective dipolar interactions between nuclear spins of spin-carrying molecules of a gas in a closed nano-cavities are independent of the spacing between all spins. We derive exact time-dependent polarization for all spins in spin-1\\/2 ensemble with spatially independent effective dipolar interactions. If the initial polarization is on a single (first) spin,$P_1(0)= 1$ then

E. B. Fel'Dman; M. G. Rudavets

2004-01-01

371

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

372

Coherent transfer of nuclear spin polarization in field-cycling NMR experiments

Coherent polarization transfer effects in a coupled spin network have been studied over a wide field range. The transfer mechanism is based on exciting zero-quantum coherences between the nuclear spin states by means of non-adiabatic field jump from high to low magnetic field. Subsequent evolution of these coherences enables conversion of spin order in the system, which is monitored after field jump back to high field. Such processes are most efficient when the spin system passes through an avoided level crossing during the field variation. The polarization transfer effects have been demonstrated for N-acetyl histidine, which has five scalar coupled protons; the initial spin order has been prepared by applying RF-pulses at high magnetic field. The observed oscillatory transfer kinetics is taken as a clear indication of a coherent mechanism; level crossing effects have also been demonstrated. The experimental data are in very good agreement with the theoretical model of coherent polarization transfer. The method suggested is also valid for other types of initial polarization in the spin system, most notably, for spin hyperpolarization.

Pravdivtsev, Andrey N.; Yurkovskaya, Alexandra V.; Ivanov, Konstantin L., E-mail: ivanov@tomo.nsc.ru [International Tomography Center, Siberian Branch of the Russian Academy of Science, Institutskaya 3a, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova 2, Novosibirsk 630090 (Russian Federation); Vieth, Hans-Martin [Institut für Experimental Physik, Freie Universität Berlin, Arnimallee 14, Berlin 14195 (Germany)] [Institut für Experimental Physik, Freie Universität Berlin, Arnimallee 14, Berlin 14195 (Germany)

2013-12-28

373

Nuclear orientation of radon isotopes by spin-exchange optical pumping

This paper reports the first demonstration of nuclear orientation of radon atoms. The method employed was spin exchange with potassium atoms polarized by optical pumping. The radon isotopes were produced at the ISOLDE isotope separator of CERN. The nuclear alignment of /sup 209/Rn and /sup 223/Rn has been measured by observation of ..gamma..-ray anisotropies and the magnetic dipole moment for /sup 209/Rn has been measured by the nuclear-magnetic-resonance method to be chemically bond..mu..chemically bond = 0.838 81(39)..mu../sub N/.

Kitano, M.; Calaprice, F.P.; Pitt, M.L.; Clayhold, J.; Happer, W.; Kadar-Kallen, M.; Musolf, M.; Ulm, G.; Wendt, K.; Chupp, T.

1988-05-23

374

Spin-echo NMR of 159Tb in a single crystal of TbNi5

The field dependence of the hyperfine splittings of 159Tb in a single crystal of TbNi5 has been studied at liquid helium temperature by spin-echo NMR. The field, up to 8 tesla, was applied along the direction of easy magnetization of the crystal. Our measurements are in almost perfect agreement with computation based on the mean values of the crystal field

C. Carboni; D. Gignoux; A. Tari

1995-01-01

375

Transient Dynamics in Magnetic Force Microscopy for a Single-Spin Measurement

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

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

2002-10-01

376

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

377

Preserving hyperpolarised nuclear spin order to study cancer metabolism

: Gyromagnetic ratio of the nucleus of interest (in rad/Ts) • ?: Chemical shift of the nucleus of interest (in ppm) • B0: Magnetic field strength (in Tesla) xii LIST OF MAIN ABBREVIATIONS • ?0: Larmor frequency of the nucleus of interest (in rad/s); ?0 = ??B0 • I... concepts The magnetic moment, ~µ, indicates that a particle can interact with an external magnetic field and is defined as the product of the gyromagnetic ratio of the isotope, ?, with its spin: ~µ = ?~I. (1.1) The gyromagnetic ratio can be either positive...

Marco-Rius, Irene

2014-06-10

378

Model for optically-induced nuclear spin polarization in gallium arsenide

NASA Astrophysics Data System (ADS)

New technologies and corresponding research fields have recently emerged that aim to develop solid-state devices based on large polarizations of electron and/or nuclear spins. These include spin-based strategies for parallel information processing through quantum entanglement ("quantum computing") and semi-classical electronic devices controlled via the spin degree of freedom ("spintronics"). A new rule of thumb - polarization has application - makes the optically pumped semiconductor an interesting system, as it exhibits both large electron and nuclear polarizations. However, several aspects of the process by which nuclear polarization is generated through optical pumping were not understood prior to this thesis, even for the most well studied semiconductor, GaAs. These include the dependence of the nuclear polarization on laser power, irradiation time, and especially on photon energy, which exhibits a dramatic peak near 1.5 eV. This thesis presents a quantitative model for optical nuclear polarization in GaAs. The model makes predictions for all quantities observable in a hulk optically pumped NMR (OPNMR) spectrum: the OPNMR signal magnitude, the hyperfine shift of the NMR frequency, and the nuclear spin temperature. The model may help researchers to optimize experimental conditions for maximizing nuclear polarization in spintronics or quantum computing architectures. A clear correlation is shown between the OPNMR signal and the photoconductivity. A photoconductivity model is developed herein that accounts for the varying penetration depth of the light with photon energy and for the presence of band-to-band and band-to-defect recombination of charge carriers. The model's predictions agree well with the photoconductivity data. The photoconductivity model is then combined with a nuclear polarization model. The resulting picture for near-band-gap (1.495 eV ? by ? 1.6 eV) optical nuclear polarization is as follows. Optical absorption generates free, non-equilibrium electron spins, whose polarization depends on the light polarization. During their excited-state lifetime, these electrons may relax into shallow-donor-bound states, where they experience a strong hyperfine interaction and can cross-relax with nuclear spins. The nuclear polarization near shallow donor defects then evolves over space and time according to a diffusion equation that accounts for localized generation and loss. This model predicts the photon-energy dependence and laser-power dependence of the OPNMR signal very well. The peak at 1.5 eV is predicted to arise from an optimal balance between a high nuclear polarization and a large irradiation volume. Both theory and experiment exhibit a deviation from linear growth of OPNMR signal with laser power at high powers and an earlier onset of non-linear growth for higher photon energy. Finally, the model predicts a time-dependent hyperfine shift of the NMR frequency that fits the data with quantitative agreement. All free parameters within the model are constrained through the fitting of these various data sets. With this model, analytical expressions are derived for helicity asymmetries in OPNMR spectra. These asymmetries are related simply enough to electron spin parameters that they provide a methodology for extracting the initially-excited and steady-state electron spin polarizations from OPNMR spectra, allowing the dependence of these polarizations on temperature and photon-energy to be investigated herein. The OPNMR asymmetry is furthermore used as a local thermometer of the irradiated volume, which provides experimental verification of a quantitative model for laser heating. Several unusual effects in optically pumped GaAs are characterized. Perhaps the most dramatic is a bi-exponential decay of the photoconductivity with irradiation time, observed at all near-band-gap photon energies. This serves as clear evidence of photoquenching of the deep defect known as EL2 under the conditions typical of OPNMR measurements. Further experiments are suggested to complete the studies in this

Coles, Patrick Joseph

379

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

380

Density-Functional and Coupled-Cluster Singles-and-Doubles Calculations of the Nuclear

.7 ppm for incarcerated o-benzyne. For the indirect spin-spin coupling constants, the CCSD model, suggesting large incarceration effects. 1. Introduction The NMR shielding tensor of the triply bonded carbon of Warmuth, o-benzyne was trapped by guest incarceration inside a molecular container, allowing its nuclear

Helgaker, Trygve

381

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

382

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

383

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

384

NASA Astrophysics Data System (ADS)

Molecular beam epitaxy (MBE) is an extremely versatile thin film technique, which can produce single-crystal layers with atomic dimensional controls and thus permit the preparation of novel structures and devices tailored to meet specific needs. Spin relaxation time ts is one of the key features in spin-related phenomena and thus of great importance for spintronics. In this work, we prepare high quality samples, mainly of CdTe epilayers, by MBE, characterize their spin relaxation dynamics, and discuss the results theoretically. First, with the goal of understanding the mechanisms of electron relaxation dynamics and nuclear spin enhancement, we focus on the growth and characterization of CdTe epilayers. By changing the shutter sequences and inserting ZnSe buffer layer, we have reproducibly grown (111) and (100) CdTe epilayers of high crystalline qualities by MBE, despite the large lattice mismatch between CdTe and GaAs substrate. Then we investigate ts for the (111) and (100) CdTe epilayers. It is found that for the (111) CdTe, spin relaxation rate t-1s is significantly enhanced and shows no temperature dependence through 130K to 300K, while t-1s for the (100) CdTe is strongly affected by the temperature. It is also found that t-1s is dependent on material quality for both (111) and (100) CdTe. We theoretically discuss the effect of strain and defect on spin relaxation time of CdTe. It is the first experimental observation of the effect of strain on t-1s in a II-VI semiconductor material. Second, the growth and characterization of ZnTe/ZnSe related type II quantum structures, or quantum dots (QDs), are also presented in this work. The PL of Zn-Se-Te related type II quantum structures show blue shifts with higher intensities of exciting laser, an indication of type II QDs. Besides being an attractive method to p-type dope wide bandgap materials, the resulting material may be a promising structure for spin enhancement properties. Third, we present the study of the enhancement of nuclear spin polarization through pumping laser. We find strong enhancement both in bulk CdTe as well as in CdTe epilayers, independent of the helicity of the laser, which is on the contrary to the prior reports by others. Compared with GaAs crystal, we ascribe this independence to the surface spin-dependent recombination. GaAs/AlAs and GaAs/GaAlAs multiple coupled double quantum wells (QWs), and CdTe/CdMgTe QW have also been grown and explored. The measurements show good quality of the material and are consistent with the designed structures. Last, we summary the work and propose the future directions. Samples are in-situ monitored by reflection high energy electron diffraction (RHEED). Post growth characterization techniques, such as time resolved Kerr rotation (TRKR), X-ray diffraction (XRD), photoluminescence (PL), and optical pumping nuclear magnetic resonance (OPNMR), are introduced and applied to the samples.

Zhang, Qiang

385

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

386

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

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

Goryca, Mateusz; Kossacki, Piotr; Golnik, Andrzej; Kazimierczuk, Tomasz; Nawrocki, Michal [Institute of Experimental Physics, University of Warsaw, Hoza 69, 00-681 Warszawa (Poland); Wojnar, Piotr [Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warszawa (Poland)

2010-01-04

387

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

388

Reconstructing labroid evolution with single-copy nuclear DNA.

Fifteen per cent of all living fishes are united in a single suborder (Labroidei) and display a dazzling array of behavioural and ecological traits. The labroids are considered monophyletic and members share a pharyngeal jaw apparatus (PJA) modified for crushing and processing prey. Outside of the explicitly functional PJA, there is no corroborative evidence for a monophyletic Labroidei. Here, we report the first molecular phylogenetic analysis of the suborder. Contrary to morphology-based phylogenies, our single-copy nuclear DNA data do not support labroid families as a natural group. Our data indicate that pharyngognathy has evolved independently among labroid families and that characters of the PJA are not reliable markers of perciform evolution. This work 'crushes' conventional views of fish phylogeny and should engender novel concepts of piscine life history evolution. PMID:9263469

Streelman, J T; Karl, S A

1997-01-01

389

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

390

Observation and electric current control of a local spin in a single-molecule magnet

In molecular spintronics, the spin state of a molecule may be switched on and off by changing the molecular structure. Here, we switch on and off the molecular spin of a double-decker bis(phthalocyaninato)terbium(III) complex (TbPc2) adsorbed on an Au(111) surface by applying an electric current via a scanning tunnelling microscope. The dI/dV curve of the tunnelling current recorded onto a TbPc2 molecule shows a Kondo peak, the origin of which is an unpaired spin of a ?-orbital of a phthalocyaninato (Pc) ligand. By applying controlled current pulses, we could rotate the upper Pc ligand in TbPc2, leading to the disappearance and reappearance of the Kondo resonance. The rotation shifts the molecular frontier-orbital energies, quenching the ?-electron spin. Reversible switching between two stable ligand orientations by applying a current pulse should make it possible to code information at the single-molecule level. PMID:21364556

Komeda, Tadahiro; Isshiki, Hironari; Liu, Jie; Zhang, Yan-Feng; Lorente, Nicolás; Katoh, Keiichi; Breedlove, Brian K.; Yamashita, Masahiro

2011-01-01

391

Relaxation of excited spin, orbital, and valley qubit states in single electron silicon quantum dots

We expand on previous work that treats relaxation physics of low-lying excited states in ideal, single electron, silicon quantum dots in the context of quantum computing. These states are of three types: orbital, valley, and spin. The relaxation times depend sensitively on system parameters such as the dot size and the external magnetic field. Generally, however, orbital relaxation times are short in strained silicon (from a tenth of a microsecond to picoseconds), spin relaxation times are long (microseconds to greater than seconds), while valley relaxation times are expected to lie in between. The focus is on relaxation due to emission or absorption of phonons, but for spin relaxation we also consider competing mechanisms such as charge noise. Where appropriate, comparison is made to reference systems such as quantum dots in III-V materials and silicon donor states. The phonon bottleneck effect is shown to be rather small in the silicon dots of interest. We compare the theoretical predictions to some recent spin relaxation experiments and comment on the possible effects of non-ideal dots.

Charles Tahan; Robert Joynt

2013-02-28

392

To test whether distances derived from paramagnetic broadening of (15)N heteronuclear single quantum coherence (HSQC) resonances could be used to determine the global fold of a large, perdeuterated protein, we used site-directed spin-labeling of 5 amino acids on the surface of (15)N-labeled eukaryotic translation initiation factor 4E (eIF4E). eIF4E is a 25 kDa translation initiation protein, whose solution structure was previously solved in a 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate hydrate (CHAPS) micelle of total molecular mass approximately 45-50 kDa. Distance-dependent line broadening consistent with the three-dimensional structure of eIF4E was observed for all spin-label substitutions. The paramagnetic broadening effects (PBEs) were converted into distances for modeling by a simple method comparing peak heights in (15)N-HSQC spectra before and after reduction of the nitroxide spin label with ascorbic acid. The PBEs, in combination with HN-HN nuclear Overhauser effects (NOEs) and chemical shift index (CSI) angle restraints, correctly determined the global fold of eIF4E with a backbone precision of 2.3 A (1.7 A for secondary structure elements). The global fold was not correctly determined with the HN-HN NOEs and CSI angles alone. The combination of PBEs with simulated restraints from another nuclear magnetic resonance (NMR) method for global fold determination of large proteins (methyl-protonated, highly deuterated samples) improved the quality of calculated structures. In addition, the combination of the two methods simulated from a crystal structure of an all alpha-helical protein (40 kDa farnesyl diphoshphate synthase) correctly determined the global fold where neither method individually was successful. These results show the potential feasibility of obtaining medium-resolution structures for proteins in the 40-100 kDa range via NMR. PMID:10820006

Battiste, J L; Wagner, G

2000-05-01

393

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

394

New technique for single-scan T1 measurements using solid echoes. [for spin-lattice relaxation time

NASA Technical Reports Server (NTRS)

A simple technique for single-scan T1 measurements in solids is proposed and analyzed for single exponential spin-lattice relaxation. In this technique, the direct spin heating caused by the sampling process is significantly reduced in comparison with conventional techniques by utilizing the 'solid echo' to refocus the magnetization. The applicability of this technique to both the solid and liquid phases is demonstrated.

Burum, D. P.; Elleman, D. D.; Rhim, W. K.

1978-01-01

395

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

396

According to quantum mechanics, spin—the intrinsic angular momentum of an electron, nucleus, or elementary particle at rest—is\\u000a a decidedly nonclassical concept. The ? spin statistics theorem of ? quantum statistics distinguishes bosons and fermions\\u000a obeying ? Bose-Einstein statistics or ? Fermi-Dirac statistics, respectively, depending on whether the particle's spin is\\u000a an even or odd multiple of h\\/2, with h =

Klaus Hentschel

397

Observation of high-temperature spin fluctuations in UBe13 by nuclear-spin relaxation

NASA Astrophysics Data System (ADS)

We report the extension of measurements of the 9Be spin-lattice relaxation rate in UBe13 from 300 up to 1000 K. They reflect the fluctuating local magnetic field at the site of the 9Be nuclei. Above about 100 K, there appears a new contribution in addition to the rate observed at lower temperatures. The high temperature contribution is modeled in terms of the thermal excitation of low-lying states of the U3+ ion along lines used by Felton et al. to explain their measurements of the specific heat. Our results indicate a splitting of 200±20 K between the ground and excited states of the system, and a lifetime of 8×10-14 s for the excited states (width =95 K).

Clark, W. G.; Wong, W. H.; Hines, W. A.; Lan, M. D.; MacLaughlin, D. E.; Fisk, Z.; Smith, J. L.; Ott, H. R.

1988-04-01

398

Theoretical model for enrichment of CH{sub 3}F nuclear-spin isomers by resonant microwave radiation

A theoretical model of coherent control of nuclear-spin isomers by microwave radiation has been developed. The model accounts the M degeneracy of molecular states and molecular center-of-mass motion. The model has been applied to the {sup 13}CH{sub 3}F molecules. Microwave radiation excites the para state (J=11, K=1) which is mixed by the nuclear-spin-spin interaction with the ortho state (9,3). Dependences of the isomer enrichment and conversion rates on the radiation frequency have been calculated. Both spectra consist of two resonances situated at the centers of nuclear-spin-allowed and -forbidden transitions of the molecule. Larger enrichment, up to 7%, can be produced by strong radiation resonant to the forbidden transition. The spin conversion rate can be increased by two orders of magnitude at this resonance.

Permyakova, O.I.; Ilisca, E.; Chapovsky, P.L. [Institute of Semiconductor Physics, Russian Academy of Sciences, 630090 Novosibirsk (Russian Federation); Laboratoire de Physique Theorique de la Matiere Condensee, Universite Paris 7-Denis Diderot, 2, Place Jussieu, 75251 Paris Cedex 05 (France); Institute of Automation and Electrometry, Russian Academy of Sciences, 630090 Novosibirsk (Russian Federation)

2003-03-01

399

Nuclear Spin-Echo Fourier-Transform Mapping Spectroscopy for Broad NMR Lines in Solids

NASA Astrophysics Data System (ADS)

A basic theoretical description of nuclear spin-echo Fourier-transform mapping spectroscopy (NSEFTMS) for broad NMR lines was derived from the well-established time-domain spin-echo theory. It has been shown that when the mapping step is less than the radiation field strength under typical conditions of spin-echo experiments, the NSEFTMS mimics precisely the original NMR spectrum. Most important, the NSEFTMS present a more efficient alternative in practice to the conventional point-by-point scanning technique that is, in general, time consuming in studying broad NMR lines in solids, especially when there exist some sharp features. A preliminary 31P NMR study of an iron (II) diphosphate (Fe 2P 2O 7) sample, which is one kind of precursor for the heterogeneous catalytic ferri-phosphate system (FePO), has been taken as an example of the application of the theory.

Tong, Y. Y.

400

A magic angle spinning (MAS) NMR technique for measurement of the distance between two homonuclear sites separated by as much as 0.5 nm is demonstrated. This is achieved by proton decoupling during the magnetization exchange process, greatly attenuating the influence of abundant nuclear spins, selective isotopic labeling of both sites of interest, so that the system may be approximated as a set of magnetically dilute coupled spin pairs, and MAS with matching of the rotational resonance condition. Tyrosine ethyl ester (TEE), carbon 13 labeled at both the -CH{sub 2}- of the ester moiety and at the 4{prime}-OH aromatic carbon is used as a demonstration of the technique. Calculated data is compared to experimental data.

Raleigh, D.P.; Creuzet, F.; Das Gupta, S.K.; Levitt, M.H.; Griffin, R.G. (Massachusetts Institute of Technology, Cambridge (USA))

1989-06-07

401

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

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

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

2010-08-20

402

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

403

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

404

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

405

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

406

Spin-Lattice Relaxation Times of Single Donors and Donor Clusters in Silicon

NASA Astrophysics Data System (ADS)

An atomistic method of calculating the spin-lattice relaxation times (T1 ) is presented for donors in silicon nanostructures comprising of millions of atoms. The method takes into account the full band structure of silicon including the spin-orbit interaction. The electron-phonon Hamiltonian, and hence, the deformation potential, is directly evaluated from the strain-dependent tight-binding Hamiltonian. The technique is applied to single donors and donor clusters in silicon, and explains the variation of T1 with the number of donors and electrons, as well as donor locations. Without any adjustable parameters, the relaxation rates in a magnetic field for both systems are found to vary as B5 , in excellent quantitative agreement with experimental measurements. The results also show that by engineering electronic wave functions in nanostructures, T1 times can be varied by orders of magnitude.

Hsueh, Yu-Ling; Büch, Holger; Tan, Yaohua; Wang, Yu; Hollenberg, Lloyd C. L.; Klimeck, Gerhard; Simmons, Michelle Y.; Rahman, Rajib

2014-12-01

407

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

NASA Technical Reports Server (NTRS)

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

Singh, S. N.

1977-01-01

408

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

409

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

410

Optical and Nuclear Spin Spectroscopy in PRASEODYMIUM(3+):LANTHANUM Fluoride by Optical Pumping

NASA Astrophysics Data System (ADS)

A Stark Modulated Optical Pumping (SMOP) technique was used as a sensitive probe of optical hole-burning to study the effects of nuclear spin interactions in Pr ^{3+}:LaF_3. The results of two experiments are reported. In the first experiment, the SMOP technique is applied for optical detection of the NQR spectrum of the Pr^{3+} optical ground state. Frequency and linewidth variations of the Pr ^{3+} ground state hyperfine levels for different positions within the main ^3 H_4(Gamma1) -^1D_2(Gamma 1) inhomogeneous optical line and satellite transitions of Pr^{3+}:LaF _3 are observed. A linear increase in the broadening of the Pr^{3+} hyperfine transitions, without a shift of central frequency, is measured as the laser is tuned toward the wings of the inhomogeneous optical transition. The linear variation is attributed to electric quadrupole broadening caused by changes in local density of point defects across the Stark broadened optical transition. The optically detected NQR spectra of the satellite transitions associated with Pr ion pairs are shifted in frequency, and for most satellites are narrower in width than the NQR spectra found in the wings of the main inhomogeneous optical line. In the second experiment, direct evidence for the presence of a spin diffusion barrier or "frozen core" in Pr^{3+}:LaF _3 is observed by examining the cross relaxation between the Pr and F nuclei in a magnetic field chosen so that a pair of the optical ground state Pr^ {3+} hyperfine energy levels matches the F splitting or a multiple of the F splitting. This level crossing condition allows resonant flip-flop interactions with the nearest neighbor frozen core fluorine spins to re-populate Pr^{3+} hyperfine levels emptied by laser hole-burning, and is detected as enhanced absorption of the laser beam. The coupling of core fluorine spins to bulk fluorine spins during Pr-F cross-relaxation is measured by NMR of the bulk fluorine spin magnetization. The rate of cross relaxation between the Pr spins and the bulk F spins measured in this way is at least three to four orders of magnitude slower than that expected in the absence of a spin diffusion barrier. This reduction of coupling indicates nearly complete de-tuning of the frozen core F spins immediately surrounding the Pr^{3+} ion, cutting off resonant coupling with the bulk F spins.

Wald, Lawrence Leroy

411

(1)H nuclear spin relaxation of liquid water from molecular dynamics simulations.

We have investigated the nuclear spin relaxation properties of (1)H in liquid water with the help of molecular dynamics simulations. We have computed the (1)H nuclear spin relaxation times T1 and T2 and determined the contribution of the different interactions to the relaxation at different temperatures and for different classical water models (SPC/E, TIP3P, TIP4P, and TIP4P/2005). Among the water models considered, the TIP4P/2005 model exhibits the best agreement with the experiment. The same analysis was performed with Car-Parrinello ab initio molecular dynamics simulations of bulk water at T = 330 K, which provided results close to the experimental values at room temperature. To complete the study, we have successfully accounted for the temperature-dependence of T1 and T2 in terms of a simplified model, which considers the reorientation in finite angle jumps and the diffusive translation of water molecules. PMID:25584483

Calero, C; Martí, J; Guàrdia, E

2015-02-01

412

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

413

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

Invention of scanning tunneling microscope (STM) and atomic force microscope (AFM) initiated a new era of material science and technology characterized by 2-D imaging with atomic resolution and manipulation of individual atoms. However, for further progress in material science, and in particular in structural biology, 3-D imaging with sub-nanometer resolution is very desirable. Currently the most promising technique for 3-D imaging is magnetic resonance force microscopy (MRFM), which senses individual electron spins [1,2] with nanoscale resolution and can detect collective magnetization of about 100 nuclear spins [3]. The highest sensitivity demonstrated by MRFM is based on a time modulation technique called the oscillating cantilever-driven adiabatic reversals (OSCAAR) which requires a long phase relaxation time T 2 of measured spins, which usually corresponds to rather low temperature. For example, a temperature of 300 mK was used in the case of 3D imaging of the tobacco mosaic virus [3]. This limitation is incompatible with the room-temperature operation needed for the study of biological systems under physiological conditions.

Berman, Gennady P [Los Alamos National Laboratory; Chernobrod, Boris [Los Alamos National Laboratory

2009-01-01

414

Asymmetry and Spin-Orbit Effects in Binding Energy in the Effective Nuclear Surface Approximation

Isoscalar and isovector particle densities are derived analytically by using the approximation of a sharp edged nucleus within the local energy density approach with the proton-neutron asymmetry and spin-orbit effects. Equations for the effective nuclear-surface shapes as collective variables are derived up to the higher order corrections in the form of the macroscopic boundary conditions. The analytical expressions for the isoscalar and isovector tension coefficients of the nuclear surface binding energy and the finite-size corrections to the $\\beta $ stability line are obtained.

A. G. Magner; A. I. Sanzhur; A. M. Gzhebinsky

2008-12-19

415

NASA Astrophysics Data System (ADS)

Both kinetically balanced (KB) and kinetically unbalanced (KU) rotational London orbitals (RLO) are proposed to resolve the slow basis set convergence in relativistic calculations of nuclear spin-rotation (NSR) coupling tensors of molecules containing heavy elements [Y. Xiao and W. Liu, J. Chem. Phys. 138, 134104 (2013)]. While they perform rather similarly, the KB-RLO Ansatz is clearly preferred as it ensures the correct nonrelativistic limit even with a finite basis. Moreover, it gives rise to the same "direct relativistic mapping" between nuclear magnetic resonance shielding and NSR coupling tensors as that without using the London orbitals [Y. Xiao, Y. Zhang, and W. Liu, J. Chem. Theory Comput. 10, 600 (2014)].

Xiao, Yunlong; Zhang, Yong; Liu, Wenjian

2014-10-01

416

Optical and Nuclear Spin Spectroscopy in PRASEODYMIUM(3+):LANTHANUM Fluoride by Optical Pumping

A Stark Modulated Optical Pumping (SMOP) technique was used as a sensitive probe of optical hole-burning to study the effects of nuclear spin interactions in Pr ^{3+}:LaF_3. The results of two experiments are reported. In the first experiment, the SMOP technique is applied for optical detection of the NQR spectrum of the Pr^{3+} optical ground state. Frequency and linewidth variations

Lawrence Leroy Wald

1992-01-01

417

Nuclear structure aspects of spin-independent WIMP scattering off xenon

We study the structure factors for spin-independent WIMP scattering off xenon based on state-of-the-art large-scale shell-model calculations, which are shown to yield a good spectroscopic description of all experimentally relevant isotopes. Our results are based on the leading scalar one-body currents only. At this level and for the momentum transfers relevant to direct dark matter detection, the structure factors are in very good agreement with the phenomenological Helm form factors used to give experimental limits for WIMP-nucleon cross sections. In contrast to spin-dependent WIMP scattering, the spin-independent channel, at the one-body level, is less sensitive to nuclear structure details. In addition, we explicitly show that the structure factors for inelastic scattering are suppressed by ~ 10^{-4} compared to the coherent elastic scattering response. This implies that the detection of inelastic scattering will be able to discriminate clearly between spin-independent and spin-dependent scattering. Finally, we provide fits for all calculated structure factors.

L. Vietze; P. Klos; J. Menéndez; W. C. Haxton; A. Schwenk

2014-12-05

418

Nuclear structure aspects of spin-independent WIMP scattering off xenon

We study the structure factors for spin-independent WIMP scattering off xenon based on state-of-the-art large-scale shell-model calculations, which are shown to yield a good spectroscopic description of all experimentally relevant isotopes. Our results are based on the leading scalar one-body currents only. At this level and for the momentum transfers relevant to direct dark matter detection, the structure factors are in very good agreement with the phenomenological Helm form factors used to give experimental limits for WIMP-nucleon cross sections. In contrast to spin-dependent WIMP scattering, the spin-independent channel, at the one-body level, is less sensitive to nuclear structure details. In addition, we explicitly show that the structure factors for inelastic scattering are suppressed by ~ 10^{-4} compared to the coherent elastic scattering response. This implies that the detection of inelastic scattering will be able to discriminate clearly between spin-independent and spin-dependent scattering. Finall...

Vietze, L; Menéndez, J; Haxton, W C; Schwenk, A

2014-01-01

419

Performance Capability of Single-Cavity Vortex Gaseous Nuclear Rockets

NASA Technical Reports Server (NTRS)

An analysis was made to determine the maximum powerplant thrust-to-weight ratio possible with a single-cavity vortex gaseous reactor in which all the hydrogen propellant must diffuse through a fuel-rich region. An assumed radial temperature profile was used to represent conduction, convection, and radiation heat-transfer effects. The effect of hydrogen property changes due to dissociation and ionization was taken into account in a hydrodynamic computer program. It is shown that, even for extremely optimistic assumptions of reactor criticality and operating conditions, such a system is limited to reactor thrust-to-weight ratios of about 1.2 x 10(exp -3) for laminar flow. For turbulent flow, the maximum thrust-to-weight ratio is less than 10(exp -3). These low thrusts result from the fact that the hydrogen flow rate is limited by the diffusion process. The performance of a gas-core system with a specific impulse of 3000 seconds and a powerplant thrust-to-weight ratio of 10(exp -2) is shown to be equivalent to that of a 1000-second advanced solid-core system. It is therefore concluded that a single-cavity vortex gaseous reactor in which all the hydrogen must diffuse through the nuclear fuel is a low-thrust device and offers no improvement over a solid-core nuclear-rocket engine. To achieve higher thrust, additional hydrogen flow must be introduced in such a manner that it will by-pass the nuclear fuel. Obviously, such flow must be heated by thermal radiation. An illustrative model of a single-cavity vortex system employing supplementary flow of hydrogen through the core region is briefly examined. Such a system appears capable of thrust-to-weight ratios of approximately 1 to 10. For a high-impulse engine, this capability would be a considerable improvement over solid-core performance. Limits imposed by thermal radiation heat transfer to cavity walls are acknowledged but not evaluated. Alternate vortex concepts that employ many parallel vortices to achieve higher hydrogen flow rates offer the possibility of sufficiently high thrust-to-weight ratios, if they are not limited by short thermal-radiation path lengths.

Ragsdale, Robert G.

1963-01-01

420

Solid-state nuclear-spin quantum computer based on magnetic resonance force microscopy G. P. Berman September 1999 We propose a nuclear-spin quantum computer based on magnetic resonance force microscopy MRFM for a small number of spins.6Â8 Magnetic resonance force microscopy MRFM has ma- tured over the past few years

Hammel, P. Chris

421

NASA Astrophysics Data System (ADS)

We have studied theoretically the possibility of ultra-fast manipulation of a single electron spin in 2D semiconductor quantum dots, by means of high-frequency time-dependent electric fields. The electron spin degree of freedom is excited through spin-orbit coupling, and the procedure may be enhanced by the presence of a static magnetic field. We use quantum optimal control theory to tailor the temporal profile of the electric field in order to achieve the most effective manipulation. The scheme predicts significant control over spin operations in times of the order of picoseconds - an ultrafast time scale that permits to avoid the effects of decoherence if this scheme is to be used as a tool for quantum information processing.

Budagosky Marcilla, Jorge A.; Castro, Alberto

2015-01-01

422

Single-branch theory of ultracold Fermi gases with artificial Rashba spin-orbit coupling

We consider interacting ultracold fermions subject to Rashba spin-orbit coupling. We construct a single-branch interacting theory for the Fermi gas when the system is dilute enough so that the positive helicity branch is not occupied at all in the non-interacting ground state. We show that the theory is renormalizable in perturbation theory and therefore yields a model of polarized fermions that avoids a multi-channel treatment of the problem. Our results open the path towards a much more straightforward approach to the many-body physics of cold atoms subject to artificial vector potentials.

Daniel Maldonado-Mundo; Patrik Ohberg; Manuel Valiente

2012-12-14

423

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

424

Twist-3 single-spin asymmetries in semi-inclusive deep-inelastic scattering

NASA Astrophysics Data System (ADS)

The single-spin asymmetries for a longitudinally polarized lepton beam or a longitudinally polarized nucleon target in semi-inclusive deep-inelastic scattering are twist-3 observables. We study these asymmetries in a simple diquark spectator model of the nucleon. Analogous to the case of transverse target polarization, non-vanishing asymmetries are generated by gluon exchange between the struck quark and the target system. It is pointed out that the coupling of the virtual photon to the diquark is needed in order to preserve electromagnetic gauge invariance at the twist-3 level. The calculation indicates that previous analyses of these observables are incomplete.

Metz, A.; Schlegel, M.

2004-12-01

425

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

2014-07-02

426

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

427

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

428

NASA Astrophysics Data System (ADS)

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

Liu, Gui-Bin; Liu, Bang-Gui

2010-10-01

429

A NEW METHOD FOR EXTRACTING SPIN-DEPENDENT NEUTRON STRUCTURE FUNCTIONS FROM NUCLEAR DATA

High-energy electrons are currently the best probes of the internal structure of nucleons (protons and neutrons). By collecting data on electrons scattering off light nuclei, such as deuterium and helium, one can extract structure functions (SFs), which encode information about the quarks that make up the nucleon. Spin-dependent SFs, which depend on the relative polarization of the electron beam and the target nucleus, encode quark spins. Proton SFs can be measured directly from electron-proton scattering, but those of the neutron must be extracted from proton data and deuterium or helium-3 data because free neutron targets do not exist. At present, there is no reliable method for accurately determining spin-dependent neutron SFs in the low-momentum-transfer regime, where nucleon resonances are prominent and the functions are not smooth. The focus of this study was to develop a new method for extracting spin-dependent neutron SFs from nuclear data. An approximate convolution formula for nuclear SFs reduces the problem to an integral equation, for which a recursive solution method was designed. The method was then applied to recent data from proton and deuterium scattering experiments to perform a preliminary extraction of spin-dependent neutron SFs in the resonance region. The extraction method was found to reliably converge for arbitrary test functions, and the validity of the extraction from data was verifi ed using a Bjorken integral, which relates integrals of SFs to a known quantity. This new information on neutron structure could be used to assess quark-hadron duality for the neutron, which requires detailed knowledge of SFs in all kinematic regimes.

Kahn, Y.F.; Melnitchouk, W.

2009-01-01

430

statistics in single semiconductor nano- crystal quantum dots have been observed by Shimizu 22 . An excellentSpin quantum jumps in a singly charged quantum dot M. P. van Exter, J. Gudat, G. Nienhuis, and D quantum dot driven by a constant optical field. Using a separation of time scales we predict

Exter, Martin van

431

Single Photons Michael N. Leuenberger and Michael E. FlatteÂ´ Department of Physics and Astronomy and OSTC propose a teleportation scheme that relies only on single-photon measurements and Faraday rotation. The interaction between a photon and the two electron spins, via Faraday rotation in micro- cavities, establishes

Flatte, Michael E.

432

Spin and lattice structures of single-crystalline SrFe2As2 W. Ratcliff II,2

and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA 2 NIST Center for Neutron 2008 We use neutron scattering to study the spin and lattice structure of single-crystal SrFe2As2. In this paper, we report single-crystal neutron-scattering studies of the structural and magnetic phase

Hu, Jiangping

433

The properties of spin polarized pure neutron matter and symmetric nuclear matter are studied using the finite range simple effective interaction, upon its parametrization revisited. Out of the total twelve parameters involved, we now determine ten of them from nuclear matter, against the nine parameters in our earlier calculation, as required in order to have predictions in both spin polarized nuclear matter and finite nuclei in unique manner being free from uncertainty found using the earlier parametrization. The information on the effective mass splitting in polarized neutron matter of the microscopic calculations is used to constrain the one more parameter, that was earlier determined from finite nucleus, and in doing so the quality of the description of finite nuclei is not compromised. The interaction with the new set of parameters is used to study the possibilities of ferromagnetic and antiferromagnetic transitions in completely polarized symmetric nuclear matter. Emphasis is given to analyze the results analytically, as far as possible, to elucidate the role of the interaction parameters involved in the predictions.

B. Behera; X. Viñas; T. R. Routray; M. Centelles

2015-01-12

434

Nuclear-spin-induced cotton-mouton effect in a strong external magnetic field.

Novel, high-sensitivity and high-resolution spectroscopic methods can provide site-specific nuclear information by exploiting nuclear magneto-optic properties. We present a first-principles electronic structure formulation of the recently proposed nuclear-spin-induced Cotton-Mouton effect in a strong external magnetic field (NSCM-B). In NSCM-B, ellipticity is induced in a linearly polarized light beam, which can be attributed to both the dependence of the symmetric dynamic polarizability on the external magnetic field and the nuclear magnetic moment, as well as the temperature-dependent partial alignment of the molecules due to the magnetic fields. Quantum-chemical calculations of NSCM-B were conducted for a series of molecular liquids. The overall order of magnitude of the induced ellipticities is predicted to be 10(-11) -10(-6) rad?T(-1) ?M(-1) ?cm(-1) for fully spin-polarized nuclei. In particular, liquid-state heavy-atom systems should be promising for experiments in the Voigt setup. PMID:24862946

Fu, Li-Juan; Vaara, Juha

2014-08-01

435

Single-molecule-magnet behavior and spin changes affected by crystal packing effects.

Five Mn 3Zn 2 heterometallic complexes have been synthesized and structurally and magnetically characterized. Spin ground states up to S = 6 have been observed for these complexes and are shown to depend on the cocrystallizing cation and on the terminal ligand. Large axial zero-field interactions ( D = -1.16 K) are the result of near-parallel alignment of the Mn (III) Jahn-Teller axes. High-frequency electron paramagnetic resonance, single-crystal magnetization hysteresis, and alternating current susceptibility measurements are presented to characterize [NEt 4] 3[Mn 3Zn 2(salox) 3O(N 3) 6X 2] [X (-) = Cl (-) ( 1), Br (-) ( 2)] and [AsPh 4] 3[Mn 3Zn 2(salox) 3O(N 3) 6Cl 2] ( 3) and reveal that 1 and 2 are single-molecule magnets ( U eff = 44 K), while 3 is not. PMID:18771258

Feng, Patrick L; Koo, Changhyun; Henderson, John J; Nakano, Motohiro; Hill, Stephen; del Barco, Enrique; Hendrickson, David N

2008-10-01

436

Realization of quantum non-demolition measurement of nuclear spin 1/2 of cold ytterbium atom

NASA Astrophysics Data System (ADS)

We have demonstrated a quantum non-demolition (QND) measurement with a collective spin of cold ytterbium atoms (171Yb) via Faraday rotation interaction, and have observed 1.8-1.5+2.4 dB spin squeezing. Since 171Yb atoms have only a nuclear spin of one-half in the ground state, the system constitutes the simplest spin ensemble and is thus robust against decoherence. Furthermore, we have considered the atomic quantum swapping gate as a quantum information device using multiple Faraday rotation interactions, and have found that we can realize the quantum-domain performance for a realistic experimental condition.

Takano, T.; Namiki, R.; Takahashi, Y.

2009-04-01

437

Nuclear spin driven quantum tunneling of magnetization (QTM) phenomena, which arise from admixture of more than two orthogonal electronic spin wave functions through the couplings with those of the nuclear spins, are one of the important magnetic relaxation processes in lanthanide single molecule magnets (SMMs) in the low temperature range. Although recent experimental studies have indicated that the presence of the intramolecular f-f interactions affects their magnetic relaxation processes, little attention has been given to their mechanisms and, to the best of our knowledge, no rational theoretical models have been proposed for the interpretations of how the nuclear spin driven QTMs are influenced by the f-f interactions. Since quadruple-decker phthalocyanine complexes with two terbium or dysprosium ions as the magnetic centers show moderate f-f interactions, these are appropriate to investigate the influence of the f-f interactions on the dynamic magnetic relaxation processes. In the present paper, a theoretical model including ligand field (LF) potentials, hyperfine, nuclear quadrupole, magnetic dipolar, and the Zeeman interactions has been constructed to understand the roles of the nuclear spins for the QTM processes, and the resultant Zeeman plots are obtained. The ac susceptibility measurements of the magnetically diluted quadruple-decker monoterbium and diterbium phthalocyanine complexes, [Tb-Y] and [Tb-Tb], have indicated that the presence of the f-f interactions suppresses the QTMs in the absence of the external magnetic field (H(dc)) being consistent with previous reports. On the contrary, the faster magnetic relaxation processes are observed for [Tb-Tb] than [Tb-Y] at H(dc) = 1000 Oe, clearly demonstrating that the QTMs are rather enhanced in the presence of the external magnetic field. Based on the calculated Zeeman diagrams, these observations can be attributed to the enhanced nuclear spin driven QTMs for [Tb-Tb]. At the H(dc) higher than 2000 Oe, the magnetic relaxations become faster with increasing Hdc for both complexes, which are possibly ascribed to the enhanced direct processes. The results on the dysprosium complexes are also discussed as the example of a Kramers system. PMID:24003906

Fukuda, Takamitsu; Matsumura, Kazuya; Ishikawa, Naoto

2013-10-10

438

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

439

Symmetry-lowering lattice distortion at the spin reorientation in MnBi single crystals

NASA Astrophysics Data System (ADS)

Structural and physical properties determined by measurements on large single crystals of the anisotropic ferromagnet MnBi are reported. The findings support the importance of magnetoelastic effects in this material. X-ray diffraction reveals a structural phase transition at the spin reorientation temperature TS R=90 K. The distortion is driven by magnetoelastic coupling, and upon cooling transforms the structure from hexagonal to orthorhombic. Heat capacity measurements show a thermal anomaly at the crystallographic transition, which is suppressed rapidly by applied magnetic fields. Effects on the transport and anisotropic magnetic properties of the single crystals are also presented. Increasing anisotropy of the atomic displacement parameters for Bi with increasing temperature above TS R is revealed by neutron diffraction measurements. It is likely that this is directly related to the anisotropic thermal expansion in MnBi, which plays a key role in the spin reorientation and magnetocrystalline anisotropy. The identification of the true ground-state crystal structure reported here may be important for future experimental and theoretical studies of this permanent magnet material, which have to date been performed and interpreted using only the high-temperature structure.

McGuire, Michael A.; Cao, Huibo; Chakoumakos, Bryan C.; Sales, Brian C.

2014-11-01

440

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