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1

Control of single spin in Markovian environment  

E-print Network

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

Yuan, Haidong

2

Coherent Control of a Single Electron Spin with Electric Fields  

Microsoft Academic Search

Manipulation of single spins is essential for spin-based quantum information\\u000aprocessing. Electrical control instead of magnetic control is particularly\\u000aappealing for this purpose, since electric fields are easy to generate locally\\u000aon-chip. We experimentally realize coherent control of a single electron spin\\u000ain a quantum dot using an oscillating electric field generated by a local gate.\\u000aThe electric field induces

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

2007-01-01

3

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

4

High precision quantum control of single donor spins in silicon  

E-print Network

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

5

Quantum control and engineering of single spins in diamond  

NASA Astrophysics Data System (ADS)

The past two decades have seen intensive research efforts aimed at creating quantum technologies that leverage phenomena such as coherence and entanglement to achieve device functionalities surpassing those attainable with classical physics. While the range of applications for quantum devices is typically limited by their cryogenic operating temperatures, in recent years point defects in semiconductors have emerged as potential candidates for room temperature quantum technologies. In particular, the nitrogen vacancy (NV) center in diamond has gained prominence for the ability to measure and control its spin under ambient conditions and for its potential applications in magnetic sensing. Here we describe experiments that probe the thermal limits to the measurement and control of single NV centers to identify the origin of the system's unique temperature dependence and that define novel thermal sensing applications for single spins. We demonstrate the optical measurement and coherent control of the spin at temperatures exceeding 600 K and show that its addressability is eventually limited by thermal quenching of the optical spin readout. These measurements provide important information for the electronic structure responsible for the optical spin initialization and readout processes and, moreover, suggest that the coherence of the NV center's spin states could be harnessed for thermometry applications. To that end, we develop novel quantum control techniques that selectively probe thermally induced shifts in the spin resonance frequencies while minimizing the defect's interactions with nearby nuclear spins. We use these techniques to extend the NV center's spin coherence for thermometry by 45-fold to achieve thermal sensitivities approaching 10 mK Hz-1/2 . We show the versatility of these techniques by performing measurements in a range of magnetic environments and at temperatures as high as 500 K. Together with diamond's ideal thermal, mechanical, and chemical properties, these measurements suggest that NV center sensors could be employed in a diverse range of applications such as intracellular thermometry, microfuidic thermometry, and scanning thermal microscopy. Finally, while the development of NV center technologies is motivated by the desirable properties of isolated defects in bulk diamond, the realization of many of these technologies, such as those using the spin as a proximal sensor, require a means to control the placement of NV centers within the diamond lattice. We demonstrate a method to pattern defect formation on sub-100-nm length scales using ion implantation and electron beam lithography techniques. The ability to engineer large scale arrays of NV centers with this method holds promise for a variety of applications in quantum information science and nanoscale sensing.

Toyli, David M.

6

Control of single-spin magnetic anisotropy by exchange coupling.  

PubMed

The properties of quantum systems interacting with their environment, commonly called open quantum systems, can be affected strongly by this interaction. Although this can lead to unwanted consequences, such as causing decoherence in qubits used for quantum computation, it can also be exploited as a probe of the environment. For example, magnetic resonance imaging is based on the dependence of the spin relaxation times of protons in water molecules in a host's tissue. Here we show that the excitation energy of a single spin, which is determined by magnetocrystalline anisotropy and controls its stability and suitability for use in magnetic data-storage devices, can be modified by varying the exchange coupling of the spin to a nearby conductive electrode. Using scanning tunnelling microscopy and spectroscopy, we observe variations up to a factor of two of the spin excitation energies of individual atoms as the strength of the spin's coupling to the surrounding electronic bath changes. These observations, combined with calculations, show that exchange coupling can strongly modify the magnetic anisotropy. This system is thus one of the few open quantum systems in which the energy levels, and not just the excited-state lifetimes, can be renormalized controllably. Furthermore, we demonstrate that the magnetocrystalline anisotropy, a property normally determined by the local structure around a spin, can be tuned electronically. These effects may play a significant role in the development of spintronic devices in which an individual magnetic atom or molecule is coupled to conducting leads. PMID:24317285

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

2014-01-01

7

All optical control of a single electron spin in diamond  

E-print Network

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

8

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

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

9

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

NASA Astrophysics Data System (ADS)

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

Morello, Andrea

2011-03-01

10

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

PubMed

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

11

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

12

Excited-State Spectroscopy and Control of Single Spins in Diamond  

NASA Astrophysics Data System (ADS)

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

Fuchs, G. D.

2009-03-01

13

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

PubMed Central

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

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

2013-01-01

14

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

PubMed Central

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

15

Ultrafast single electron spin manipulation in 2D semiconductor quantum dots with optimally controlled time-dependent electric fields through spin-orbit coupling  

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

16

All-optical control of a single electron spin in diamond  

NASA Astrophysics Data System (ADS)

Precise coherent control of the individual electronic spins associated with atomlike 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 ˜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.

Chu, Y.; Markham, M.; Twitchen, D. J.; Lukin, M. D.

2015-02-01

17

Deterministic Writing and Control of the Dark Exciton Spin Using Single Short Optical Pulses  

NASA Astrophysics Data System (ADS)

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

Schwartz, I.; Schmidgall, E. R.; Gantz, L.; Cogan, D.; Bordo, E.; Don, Y.; Zielinski, M.; Gershoni, D.

2015-01-01

18

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

19

Spin-Orbit Mediated Control of Spin Qubits  

Microsoft Academic Search

We propose to use the spin-orbit interaction as a means to control electron spins in quantum dots, enabling both single-qubit and two-qubit operations. Very fast single-qubit operations may be achieved by temporarily displacing the electrons. For two-qubit operations the coupling mechanism is based on a combination of the spin-orbit coupling and the mutual long-ranged Coulomb interaction. Compared to existing schemes

Christian Flindt; Anders S. Sørensen; Karsten Flensberg

2006-01-01

20

Gate controlled spin pumping at a quantum spin Hall edge  

NASA Astrophysics Data System (ADS)

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

Narayan, Awadhesh; Hurley, Aaron; Sanvito, Stefano

2013-09-01

21

Single spin asymmetry in DVCS  

E-print Network

In the following note, we will present an estimation of the single spin asymmetry in deeply virtual Compton scattering (DVCS) which directly allows one to test predictions of the ratio of the imaginary part of the amplitude in DIS to DVCS, as well as access the skewed parton distributions at small $x$ in the DGLAP region. We find it to be large for the HERA kinematics to be accessible in forthcoming runs with polarized electrons.

A. Freund; M. Strikman

1999-06-01

22

Single-spin measurement using spin orbital entanglement  

NASA Astrophysics Data System (ADS)

Single-spin measurement represents a major challenge for spin-based quantum computation. In this paper, we propose a new method for measuring the spin of a single electron confined in a quantum dot (QD). Our strategy is based on entangling (using unitary gates) the spin and orbital degrees of freedom. An 'orbital qubit', defined by a second, empty QD, is used as an ancilla and is prepared in a known initial state. Measuring the orbital qubit will reveal the state of the (unknown) initial spin qubit, hence reducing the problem to the easier task of single charge measurement. Since spin-charge conversion is done with unit probability, single-shot measurement of an electronic spin can be, in principle, achieved. We evaluate the robustness of our method against various sources of error and discuss possible implementations.

Ionicioiu, Radu; Popescu, A. E.

2005-05-01

23

Nanoscale imaging magnetometry with single spins in diamond  

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

24

Single-shot readout of an electron spin in silicon.  

PubMed

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

25

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

SciTech Connect

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

26

Spin effects in single-electron transistors  

E-print Network

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

Granger, Ghislain

2005-01-01

27

Quantum control of proximal spins using nanoscale magnetic resonance imaging  

E-print Network

Quantum control of individual spins in condensed matter systems is an emerging field with wide-ranging applications in spintronics, quantum computation, and sensitive magnetometry. Recent experiments have demonstrated the ability to address and manipulate single electron spins through either optical or electrical techniques. However, it is a challenge to extend individual spin control to nanoscale multi-electron systems, as individual spins are often irresolvable with existing methods. Here we demonstrate that coherent individual spin control can be achieved with few-nm resolution for proximal electron spins by performing single-spin magnetic resonance imaging (MRI), which is realized via a scanning magnetic field gradient that is both strong enough to achieve nanometric spatial resolution and sufficiently stable for coherent spin manipulations. We apply this scanning field-gradient MRI technique to electronic spins in nitrogen-vacancy (NV) centers in diamond and achieve nanometric resolution in imaging, char...

Grinolds, M S; Hong, S; Lukin, M D; Walsworth, R L; Yacoby, A

2011-01-01

28

Quantum control of proximal spins using nanoscale magnetic resonance imaging  

Microsoft Academic Search

Quantum control of individual spins in condensed-matter systems is an emerging field with wide-ranging applications in spintronics, quantum computation and sensitive magnetometry. Recent experiments have demonstrated the ability to address and manipulate single electron spins through either optical or electrical techniques. However, it is a challenge to extend individual-spin control to nanometre-scale multi-electron systems, as individual spins are often irresolvable

M. S. Grinolds; P. Maletinsky; S. Hong; M. D. Lukin; R. L. Walsworth; A. Yacoby

2011-01-01

29

Coherence of single spins coupled to a nuclear spin bath of varying density  

E-print Network

The dynamics of single electron and nuclear spins in a diamond lattice with different 13C nuclear spin concentration is investigated. It is shown that coherent control of up to three individual nuclei in a dense nuclear spin cluster is feasible. The free induction decays of nuclear spin Bell states and single nuclear coherences among 13C nuclear spins are compared and analyzed. Reduction of a free induction decay time T2* and a coherence time T2 upon increase of nuclear spin concentration has been found. For diamond material with depleted concentration of nuclear spin, T2* as long as 30 microseconds and T2 of up to 1.8 ms for the electron spin has been observed. The 13C concentration dependence of T2* is explained by Fermi contact and dipolar interactions with nuclei in the lattice. It has been found that T2 decreases approximately as 1/n, where n is 13C concentration, as expected for an electron spin interacting with a nuclear spin bath.

N. Mizuochi; P. Neumann; F. Rempp; J. Beck; V. Jacques; P. Siyushev; K. Nakamura; D. Twitchen; H. Watanabe; S. Yamasaki; F. Jelezko; J. Wrachtrup

2009-05-05

30

Nanomechanical readout of a single spin  

NASA Astrophysics Data System (ADS)

The spin of a single electron in a suspended carbon nanotube can be read out by using its coupling to the nanomechanical motion of the nanotube. To show this, we consider a single electron confined within a quantum dot formed by the suspended carbon nanotube. The spin-orbit interaction induces a coupling between the spin and one of the bending modes of the suspended part of the nanotube. We calculate the response of the system to pulsed external driving of the mechanical motion using a Jaynes-Cummings model. To account for resonator damping, we solve a quantum master equation, with parameters comparable to those used in recent experiments, and show how information about the spin state of the system can be acquired by measuring the mechanical motion of the nanotube. The latter can be detected by observing the current through a nearby charge sensor.

Struck, Philipp R.; Wang, Heng; Burkard, Guido

2014-01-01

31

Single spin asymmetries in electroproduction at CLAS  

SciTech Connect

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

Harut Avakian; Latifa Elouadrhiri

2004-06-02

32

Voltage-controlled spin precession  

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

33

Quantum control of proximal spins using nanoscale magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Quantum control of individual spins in condensed-matter systems is an emerging field with wide-ranging applications in spintronics, quantum computation and sensitive magnetometry. Recent experiments have demonstrated the ability to address and manipulate single electron spins through either optical or electrical techniques. However, it is a challenge to extend individual-spin control to nanometre-scale multi-electron systems, as individual spins are often irresolvable with existing methods. Here we demonstrate that coherent individual-spin control can be achieved with few- nanometre resolution for proximal electron spins by carrying out single-spin magnetic resonance imaging (MRI), which is realized using a scanning-magnetic-field gradient that is both strong enough to achieve nanometre spatial resolution and sufficiently stable for coherent spin manipulations. We apply this scanning-field-gradient MRI technique to electronic spins in nitrogen-vacancy (NV) centres in diamond and achieve nanometre resolution in imaging, characterization and manipulation of individual spins. For NV centres, our results in individual-spin control demonstrate an improvement of nearly two orders of magnitude in spatial resolution when compared with conventional optical diffraction-limited techniques. This scanning-field-gradient microscope enables a wide range of applications including materials characterization, spin entanglement and nanoscale magnetometry.

Grinolds, M. S.; Maletinsky, P.; Hong, S.; Lukin, M. D.; Walsworth, R. L.; Yacoby, A.

2011-09-01

34

Strong mechanical driving of a single electron spin  

E-print Network

Quantum devices for sensing and computing applications require coherent quantum systems which can be manipulated in a fast and robust way. Such quantum control is typically achieved using external electric or magnetic fields which drive the system's orbital or spin degrees of freedom. However, most of these approaches require complex and unwieldy antenna or gate structures, and with few exceptions are limited to the regime of weak driving. Here, we present a novel approach to strongly and coherently drive a single electron spin in the solid state using internal strain fields in an integrated quantum device. Specifically, we study individual Nitrogen-Vacancy (NV) spins embedded in diamond mechanical oscillators and exploit the intrinsic strain coupling between spin and oscillator to strongly drive the spins. As hallmarks of the strong driving regime, we directly observe the energy spectrum of the emerging phonon-dressed states and employ our strong, continuous driving for enhancement of the NV spin coherence time. Our results constitute a first step towards strain-driven, integrated quantum devices and open new perspectives to investigate unexplored regimes of strongly driven multi-level systems and to study exotic spin dynamics in hybrid spin-oscillator devices.

Arne Barfuss; Jean Teissier; Elke Neu; Andreas Nunnenkamp; Patrick Maletinsky

2015-03-23

35

Neutron single target spin asymmetries in SIDIS  

SciTech Connect

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

Evaristo Cisbani

2010-04-01

36

Sensing electric fields using single diamond spins  

E-print Network

The ability to sensitively detect charges under ambient conditions would be a fascinating new tool benefitting a wide range of researchers across disciplines. However, most current techniques are limited to low-temperature methods like single-electron transistors (SET), single-electron electrostatic force microscopy and scanning tunnelling microscopy. Here we open up a new quantum metrology technique demonstrating precision electric field measurement using a single nitrogen-vacancy defect centre(NV) spin in diamond. An AC electric field sensitivity reaching ~ 140V/cm/\\surd Hz has been achieved. This corresponds to the electric field produced by a single elementary charge located at a distance of ~ 150 nm from our spin sensor with averaging for one second. By careful analysis of the electronic structure of the defect centre, we show how an applied magnetic field influences the electric field sensing properties. By this we demonstrate that diamond defect centre spins can be switched between electric and magnetic field sensing modes and identify suitable parameter ranges for both detector schemes. By combining magnetic and electric field sensitivity, nanoscale detection and ambient operation our study opens up new frontiers in imaging and sensing applications ranging from material science to bioimaging.

Florian Dolde; Helmut Fedder; Marcus W. Doherty; Tobias Nöbauer; Florian Rempp; Gopalakrishnan Balasubramanian; Thomas Wolf; Friedemann Reinhard; Lloyd C. L. Hollenberg; Fedor Jelezko; Jörg Wrachtrup

2011-03-17

37

Single-spin stochastic optical reconstruction microscopy.  

PubMed

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

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

2014-10-14

38

Single spin stochastic optical reconstruction microscopy  

E-print Network

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

Matthias Pfender; Nabeel Aslam; Gerald Waldherr; Jörg Wrachtrup

2014-04-05

39

Single-spin stochastic optical reconstruction microscopy  

PubMed Central

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

2014-01-01

40

Collins Mechanism Contributions to Single Spin Asymmetry  

SciTech Connect

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

Yuan,F.

2009-05-26

41

Collins Mechanism Contributions to Single Spin Asymmetry  

SciTech Connect

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

Yuan, Feng

2009-09-11

42

Collins Mechanism Contributions to Single Spin Asymmetry  

SciTech Connect

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

Yuan,F.

2009-05-25

43

Spin-optical metamaterial route to spin-controlled photonics.  

PubMed

Spin optics provides a route to control light, whereby the photon helicity (spin angular momentum) degeneracy is removed due to a geometric gradient onto a metasurface. The alliance of spin optics and metamaterials offers the dispersion engineering of a structured matter in a polarization helicity-dependent manner. We show that polarization-controlled optical modes of metamaterials arise where the spatial inversion symmetry is violated. The emerged spin-split dispersion of spontaneous emission originates from the spin-orbit interaction of light, generating a selection rule based on symmetry restrictions in a spin-optical metamaterial. The inversion asymmetric metasurface is obtained via anisotropic optical antenna patterns. This type of metamaterial provides a route for spin-controlled nanophotonic applications based on the design of the metasurface symmetry properties. PMID:23661756

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

2013-05-10

44

Robust control of individual nuclear spins in diamond  

E-print Network

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

45

Ultrafast optical control of entanglement between two quantum dot spins  

E-print Network

The interaction between two quantum bits enables entanglement, the two-particle correlations that are at the heart of quantum information science. In semiconductor quantum dots much work has focused on demonstrating single spin qubit control using optical techniques. However, optical control of entanglement of two spin qubits remains a major challenge for scaling from a single qubit to a full-fledged quantum information platform. Here, we combine advances in vertically-stacked quantum dots with ultrafast laser techniques to achieve optical control of the entangled state of two electron spins. Each electron is in a separate InAs quantum dot, and the spins interact through tunneling, where the tunneling rate determines how rapidly entangling operations can be performed. The two-qubit gate speeds achieved here are over an order of magnitude faster than in other systems. These results demonstrate the viability and advantages of optically controlled quantum dot spins for multi-qubit systems.

Danny Kim; Samuel G. Carter; Alex Greilich; Allan Bracker; Daniel Gammon

2010-07-21

46

Universal dynamical decoupling of a single solid-state spin from a spin bath  

E-print Network

Controlling the interaction of a single quantum system with its environment is a fundamental challenge in quantum science and technology. We dramatically suppress the coupling of a single spin in diamond with the surrounding spin bath by using double-axis dynamical decoupling. The coherence is preserved for arbitrary quantum states, as verified by quantum process tomography. The resulting coherence time enhancement is found to follow a general scaling with the number of decoupling pulses. No limit is observed for the decoupling action up to 136 pulses, for which the coherence time is enhanced more than 25 times compared to spin echo. These results uncover a new regime for experimental quantum science and allow to overcome a major hurdle for implementing quantum information protocols.

de Lange, G; Ristè, D; Dobrovitski, V V; Hanson, R

2010-01-01

47

Universal dynamical decoupling of a single solid-state spin from a spin bath  

E-print Network

Controlling the interaction of a single quantum system with its environment is a fundamental challenge in quantum science and technology. We dramatically suppress the coupling of a single spin in diamond with the surrounding spin bath by using double-axis dynamical decoupling. The coherence is preserved for arbitrary quantum states, as verified by quantum process tomography. The resulting coherence time enhancement is found to follow a general scaling with the number of decoupling pulses. No limit is observed for the decoupling action up to 136 pulses, for which the coherence time is enhanced more than 25 times compared to spin echo. These results uncover a new regime for experimental quantum science and allow to overcome a major hurdle for implementing quantum information protocols.

G. de Lange; Z. H. Wang; D. Ristè; V. V. Dobrovitski; R. Hanson

2010-10-21

48

Ultrafast optical control of individual quantum dot spin qubits.  

PubMed

Single spins in semiconductor quantum dots form a promising platform for solid-state quantum information processing. The spin-up and spin-down states of a single electron or hole, trapped inside a quantum dot, can represent a single qubit with a reasonably long decoherence time. The spin qubit can be optically coupled to excited (charged exciton) states that are also trapped in the quantum dot, which provides a mechanism to quickly initialize, manipulate and measure the spin state with optical pulses, and to interface between a stationary matter qubit and a 'flying' photonic qubit for quantum communication and distributed quantum information processing. The interaction of the spin qubit with light may be enhanced by placing the quantum dot inside a monolithic microcavity. An entire system, consisting of a two-dimensional array of quantum dots and a planar microcavity, may plausibly be constructed by modern semiconductor nano-fabrication technology and could offer a path toward chip-sized scalable quantum repeaters and quantum computers. This article reviews the recent experimental developments in optical control of single quantum dot spins for quantum information processing. We highlight demonstrations of a complete set of all-optical single-qubit operations on a single quantum dot spin: initialization, an arbitrary SU(2) gate, and measurement. We review the decoherence and dephasing mechanisms due to hyperfine interaction with the nuclear-spin bath, and show how the single-qubit operations can be combined to perform spin echo sequences that extend the qubit decoherence from a few nanoseconds to several microseconds, more than 5 orders of magnitude longer than the single-qubit gate time. Two-qubit coupling is discussed, both within a single chip by means of exchange coupling of nearby spins and optically induced geometric phases, as well as over longer-distances. Long-distance spin-spin entanglement can be generated if each spin can emit a photon that is entangled with the spin, and these photons are then interfered. We review recent work demonstrating entanglement between a stationary spin qubit and a flying photonic qubit. These experiments utilize the polarization- and frequency-dependent spontaneous emission from the lowest charged exciton state to single spin Zeeman sublevels. PMID:24006335

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

2013-09-01

49

Electron Spin in Single Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

We review aspects of electrical transport in metallic single wall carbon nanotubes (SWCNT) related to the spin of the conductance electrons. For large contact resistances, R ? h/2e2, a SWCNT exhibits Coulomb blockade, and transmission can only occur, when a gate voltage leads to an energy degeneracy for two different numbers of electrons in the SWCNT. The Coulomb blockade gate voltage change is directly proportional to the addition energy for single electron tunnelling. In certain ideal cases every second of the populated electronic states has a higher addition energy, indicating that two spindegenerate electrons are roomed at each orbital state. A low addition energy therefore corresponds to approaching an even number of electrons. The odd-even alternation can be checked in a magnetic field, since then the odd additional electron may enter in one of two Zeeman states. If the high resistance contact is a tunnel junction, the transmission reflects the density of states. This leads to a direct detection of the so-called Luttinger liquid state of the electrons. Ferromagnetic contacts to the SWCNT leads to a conductance which depends on the orientation of the magnetic domains in the contacts. The magnetoresistance effect can be much larger than expected from a simple spin-valve phenomenon. For any intermediate normal metal (Au) contact resistances, R ˜ h/2e2, the Coulomb blockade may still separate the single electron states in the SWCNT with odd and even numbers of electrons. However, at the lowest temperatures the transmission only shows Coulomb blockade for even number of electrons. In the situations with odd number of electrons a coherent tunnelling process dominates. This shortage of the blockade is rooted in the Kondo states formed in the two Au electrodes by exchange interaction due to the spin state in the SWCNT. This tunnelling process is a result of a net spin on the SWCNT and consequently a spin degeneracy. A triplet state is forced into degeneracy with the singlet state in a suitable magnetic field. The situation in a magnetic field is particularly simple in a SWCNT, in contrast to conventional quantum dots, because the tiny diameter of the SWCNT practically speaking precludes orbital effects.

Lindelof, P. E.; Borggreen, J.; Jensen, A.; Nygård, J.; Poulsen, P. R.

2003-10-01

50

Electron Spin in Single Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

We review aspects of electrical transport in metallic single wall carbon nanotubes (SWCNT) related to the spin of the conductance electrons. For large contact resistances, R?h/2e2, a SWCNT exhibits Coulomb blockade, and transmission can only occur, when a gate voltage leads to an energy degeneracy for two different numbers of electrons in the SWCNT. The Coulomb blockade gate voltage change is directly proportional to the addition energy for single electron tunnelling. In certain ideal cases every second of the populated electronic states has a higher addition energy, indicating that two spindegenerate electrons are roomed at each orbital state. A low addition energy therefore corresponds to approaching an even number of electrons. The odd-even alternation can be checked in a magnetic field, since then the odd additional electron may enter in one of two Zeeman states. If the high resistance contact is a tunnel junction, the transmission reflects the density of states. This leads to a direct detection of the so-called Luttinger liquid state of the electrons. Ferromagnetic contacts to the SWCNT leads to a conductance which depends on the orientation of the magnetic domains in the contacts. The magnetoresistance effect can be much larger than expected from a simple spin-valve phenomenon. For any intermediate normal metal (Au) contact resistances, Rh/2e2, the Coulomb blockade may still separate the single electron states in the SWCNT with odd and even numbers of electrons. However, at the lowest temperatures the transmission only shows Coulomb blockade for even number of electrons. In the situations with odd number of electrons a coherent tunnelling process dominates. This shortage of the blockade is rooted in the Kondo states formed in the two Au electrodes by exchange interaction due to the spin state in the SWCNT. This tunnelling process is a result of a net spin on the SWCNT and consequently a spin degeneracy. A triplet state is forced into degeneracy with the singlet state in a suitable magnetic field. The situation in a magnetic field is particularly simple in a SWCNT, in contrast to conventional quantum dots, because the tiny diameter of the SWCNT practically speaking precludes orbital effects.

Lindelof, P. E.; Borggreen, J.; Jensen, A.; Nygård, J.; Poulsen, P. R.

51

Spin-gating of a conventional aluminum single electron transistor  

NASA Astrophysics Data System (ADS)

We report the realization of a single electron transistor in which electron transport from an aluminum source electrode to an aluminum drain electrode via an aluminum island is controlled by spins in a capacitively coupled magnetic gate electrode. The origin of the effect is in the change of the chemical potential on the gate, formed by the ferromagnetic semiconductor GaMnAs, with changing the direction of the magnetization. In agreement with experimental observations, microscopically calculated anisotropies of the chemical potential with respect to the magnetization orientation are of the order of 10?V which is comparable to the electrical gate voltages required to control the on and off state of the single electron transistor. Our phenomenon belongs to the family of anisotropic magnetoresistance effects which can be observed in ohmic, tunneling or other device geometries. In our case, the entire phenomenon is coded in the dependence of the chemical potential on the spin orientation which allowed us to remove the spin functionality from all current contacts and channels and place it in the capacitively coupled gate electrode. Our spintronic device therefore operates without spin current.

Zarbo, Liviu P.; Ciccarelli, Chiara; Irvine, Andy; Wunderlich, Jörg; Champion, Richard; Gallagher, Brian; Jungwirth, Tomáš; Ferguson, Andrew

2012-02-01

52

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

53

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

54

Switchable spin-current source controlled by magnetic domain walls.  

PubMed

Using nonlocal spin injection, spin-orbit coupling, or spincaloritronic effects, the manipulation of pure spin currents in nanostructures underlies the development of new spintronic devices. Here, we demonstrate the possibility to create switchable pure spin current sources, controlled by magnetic domain walls. When the domain wall is located at a given point of the magnetic circuit, a pure spin current is injected into a nonmagnetic wire. Using the reciprocal measurement configuration, we demonstrate that the proposed device can also be used as a pure spin current detector. Thanks to its simple geometry, this device can be easily implemented in spintronics applications; in particular, a single current source can be used both to induce the domain wall motion and to generate the spin signal. PMID:24874296

Savero Torres, W; Laczkowski, P; Nguyen, V D; Rojas Sanchez, J C; Vila, L; Marty, A; Jamet, M; Attané, J P

2014-07-01

55

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

56

Measuring mechanical motion with a single spin  

NASA Astrophysics Data System (ADS)

We study theoretically the measurement of a mechanical oscillator using a single two-level system as a detector. In a recent experiment, we used a single electronic spin associated with a nitrogen-vacancy center in diamond to probe the thermal motion of a magnetized cantilever at room temperature (Kolkowitz et al 2012 Science 335 1603). Here, we present a detailed analysis of the sensitivity limits of this technique, as well as the possibility to measure the zero-point motion of the oscillator. Further, we discuss the issue of measurement backaction in sequential measurements and find that although backaction heating can occur, it does not prohibit the detection of zero-point motion. Throughout the paper, we focus on the experimental implementation of a nitrogen-vacancy center coupled to a magnetic cantilever; however, our results are applicable to a wide class of spin-oscillator systems. The implications for the preparation of nonclassical states of a mechanical oscillator are also discussed.

Bennett, S. D.; Kolkowitz, S.; Unterreithmeier, Q. P.; Rabl, P.; Bleszynski Jayich, A. C.; Harris, J. G. E.; Lukin, M. D.

2012-12-01

57

Controlling the quantum dynamics of a mesoscopic spin bath in diamond  

PubMed Central

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

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

2012-01-01

58

Dynamically generated pure spin current in single-layer graphene  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

59

Dynamic polarization of single nuclear spins by optical pumping of nitrogen-vacancy color centers in diamond at room temperature.  

PubMed

We report a versatile method to polarize single nuclear spins in diamond, based on optical pumping of a single nitrogen-vacancy (NV) defect and mediated by a level anticrossing in its excited state. A nuclear-spin polarization higher than 98% is achieved at room temperature for the 15N nuclear spin associated with the NV center, corresponding to microK effective nuclear-spin temperature. We then show simultaneous initialization of two nuclear spins in the vicinity of a NV defect. Such robust control of nuclear-spin states is a key ingredient for further scaling up of nuclear-spin based quantum registers in diamond. PMID:19257552

Jacques, V; Neumann, P; Beck, J; Markham, M; Twitchen, D; Meijer, J; Kaiser, F; Balasubramanian, G; Jelezko, F; Wrachtrup, J

2009-02-01

60

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

61

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

PubMed Central

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

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

2014-01-01

62

RHIC spin flipper AC dipole controller  

SciTech Connect

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

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

2011-03-28

63

Sensing and atomic-scale structure analysis of single nuclear spin clusters in diamond  

E-print Network

Single-molecule nuclear magnetic resonance (NMR) is a crown-jewel challenge in the field of magnetic resonance spectroscopy and has important applications in chemical analysis and in quantum computing. Recently, it becomes possible to tackle this grand challenge thanks to experimental advances in preserving quantum coherence of nitrogen-vacancy (NV) center spins in diamond as a sensitive probe and theoretical proposals on atomic-scale magnetometry via dynamical decoupling control. Through decoherence measurement of NV centers under dynamical decoupling control, sensing of single $^{13}\\textbf{C}$ at nanometer distance has been realized. Toward the ultimate goal of structure analysis of single molecules, it is highly desirable to directly measure the interactions within single nuclear spin clusters. Here we sensed a single $^{13}\\textbf{C}$-$^{13}\\textbf{C}$ nuclear spin dimer located about 1 nm from the NV center and characterized the interaction between the two nuclear spins, by measuring NV center spin decoherence under various dynamical decoupling control. From the measured interaction we derived the spatial configuration of the dimer with atomic-scale resolution. These results demonstrate that central spin decoherence under dynamical decoupling control is a feasible probe for NMR structure analysis of single molecules.

Fazhan Shi; Xi Kong; Pengfei Wang; Fei Kong; Nan Zhao; Ren-Bao Liu; Jiangfeng Du

2013-09-25

64

Macroscopic rotation of photon polarization induced by a single spin  

NASA Astrophysics Data System (ADS)

Entangling a single spin to the polarization of a single incoming photon, generated by an external source, would open new paradigms in quantum optics such as delayed-photon entanglement, deterministic logic gates or fault-tolerant quantum computing. These perspectives rely on the possibility that a single spin induces a macroscopic rotation of a photon polarization. Such polarization rotations induced by single spins were recently observed, yet limited to a few 10?3 degrees due to poor spin–photon coupling. Here we report the enhancement by three orders of magnitude of the spin–photon interaction, using a cavity quantum electrodynamics device. A single hole spin in a semiconductor quantum dot is deterministically coupled to a micropillar cavity. The cavity-enhanced coupling between the incoming photons and the solid-state spin results in a polarization rotation by ±6° when the spin is optically initialized in the up or down state. These results open the way towards a spin-based quantum network.

Arnold, Christophe; Demory, Justin; Loo, Vivien; Lemaître, Aristide; Sagnes, Isabelle; Glazov, Mikhaïl; Krebs, Olivier; Voisin, Paul; Senellart, Pascale; Lanco, Loïc

2015-02-01

65

Macroscopic rotation of photon polarization induced by a single spin.  

PubMed

Entangling a single spin to the polarization of a single incoming photon, generated by an external source, would open new paradigms in quantum optics such as delayed-photon entanglement, deterministic logic gates or fault-tolerant quantum computing. These perspectives rely on the possibility that a single spin induces a macroscopic rotation of a photon polarization. Such polarization rotations induced by single spins were recently observed, yet limited to a few 10(-3) degrees due to poor spin-photon coupling. Here we report the enhancement by three orders of magnitude of the spin-photon interaction, using a cavity quantum electrodynamics device. A single hole spin in a semiconductor quantum dot is deterministically coupled to a micropillar cavity. The cavity-enhanced coupling between the incoming photons and the solid-state spin results in a polarization rotation by ±6° when the spin is optically initialized in the up or down state. These results open the way towards a spin-based quantum network. PMID:25687134

Arnold, Christophe; Demory, Justin; Loo, Vivien; Lemaître, Aristide; Sagnes, Isabelle; Glazov, Mikhaïl; Krebs, Olivier; Voisin, Paul; Senellart, Pascale; Lanco, Loïc

2015-01-01

66

Macroscopic rotation of photon polarization induced by a single spin  

PubMed Central

Entangling a single spin to the polarization of a single incoming photon, generated by an external source, would open new paradigms in quantum optics such as delayed-photon entanglement, deterministic logic gates or fault-tolerant quantum computing. These perspectives rely on the possibility that a single spin induces a macroscopic rotation of a photon polarization. Such polarization rotations induced by single spins were recently observed, yet limited to a few 10?3 degrees due to poor spin–photon coupling. Here we report the enhancement by three orders of magnitude of the spin–photon interaction, using a cavity quantum electrodynamics device. A single hole spin in a semiconductor quantum dot is deterministically coupled to a micropillar cavity. The cavity-enhanced coupling between the incoming photons and the solid-state spin results in a polarization rotation by ±6° when the spin is optically initialized in the up or down state. These results open the way towards a spin-based quantum network. PMID:25687134

Arnold, Christophe; Demory, Justin; Loo, Vivien; Lemaître, Aristide; Sagnes, Isabelle; Glazov, Mikhaïl; Krebs, Olivier; Voisin, Paul; Senellart, Pascale; Lanco, Loïc

2015-01-01

67

Anisotropic Resistivities of Precisely Oxygen Controlled Single-Crystal BiâSrâCaCuâO{sub 8+δ}: Systematic Study on {open_quote}{open_quote}Spin Gap{close_quote}{close_quote} Effect  

Microsoft Academic Search

The in-plane resistivity ρ{sub a}(T) and the out-of-plane resistivity ρ{sub c}(T) have been systematically measured for BiâSr âCaCuâO{sub 8+δ} single crystals with their oxygen contents precisely controlled. In the underdoped region, deviation from T -linear in-plane resistivity, which evidences the opening of the {open_quotes}spin gap,{close_quotes} is clearly observed, while the out-of-plane resistivity is well reproduced by the activation-type phenomenological formula

T. Watanabe; A. Matsuda; T. Fujii

1997-01-01

68

Two-qubit gate of combined single-spin rotation and interdot spin exchange in a double quantum dot.  

PubMed

A crucial requirement for quantum-information processing is the realization of multiple-qubit quantum gates. Here, we demonstrate an electron spin-based all-electrical two-qubit gate consisting of single-spin rotations and interdot spin exchange in a double quantum dot. A partially entangled output state is obtained by the application of the two-qubit gate to an initial, uncorrelated state. We find that the degree of entanglement is controllable by the exchange operation time. The approach represents a key step towards the realization of universal multiple-qubit gates. PMID:22107226

Brunner, R; Shin, Y-S; Obata, T; Pioro-Ladrière, M; Kubo, T; Yoshida, K; Taniyama, T; Tokura, Y; Tarucha, S

2011-09-30

69

Electrical control of spin relaxation in a quantum dot.  

PubMed

We demonstrate electrical control of the spin relaxation time T1 between Zeeman-split spin states of a single electron in a lateral quantum dot. We find that relaxation is mediated by the spin-orbit interaction, and by manipulating the orbital states of the dot using gate voltages we vary the relaxation rate W identical withT1(-1) by over an order of magnitude. The dependence of W on orbital confinement agrees with theoretical predictions, and from these data we extract the spin-orbit length. We also measure the dependence of W on the magnetic field and demonstrate that spin-orbit mediated coupling to phonons is the dominant relaxation mechanism down to 1 T, where T1 exceeds 1 s. PMID:18352316

Amasha, S; Maclean, K; Radu, Iuliana P; Zumbühl, D M; Kastner, M A; Hanson, M P; Gossard, A C

2008-02-01

70

Two-Dimensional Nanoscale Imaging of Gadolinium Spins via Scanning Probe Relaxometry with a Single Spin in Diamond  

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

71

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

E-print Network

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

72

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

E-print Network

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

73

OSP Quantum Mechanics: Single Measurments of Spin States Worksheet  

NSDL National Science Digital Library

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

Belloni, Mario

74

Radio Frequency Scanning Tunneling Spectroscopy for Single-Molecule Spin Resonance  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

75

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

PubMed

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

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

2014-09-26

76

Status of Sivers and Collins Single Spin Asymmetries  

E-print Network

The Sivers and Collins asymmetries are the most interesting Single Spin Asymmetries in semi-inclusive deeply inelastic scattering with transverse target polarization. In this talk we present our understanding of these phenomena.

A. V. Efremov; K. Goeke; P. Schweitzer

2007-02-15

77

Coherent control of dipolar coupled spins in large Hilbert spaces  

E-print Network

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

Sinha, Suddhasattwa

2006-01-01

78

Collins Fragmentation and the Single Transverse Spin Asymmetry  

SciTech Connect

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

Yuan, Feng; Zhou, Jian

2009-03-26

79

Geodesic motion in the singly spinning black ring spacetime  

NASA Astrophysics Data System (ADS)

We present analytical solutions of the geodesic equations of test particles and light in the five-dimensional singly spinning black ring spacetime for special cases, since it does not appear possible to separate the Hamilton-Jacobi equation for singly spinning black rings in general. Based on the study of the polynomials in the equations of motion we characterize the motion of test particles and light and discuss the associated orbits.

Grunau, Saskia; Kagramanova, Valeria; Kunz, Jutta; Lämmerzahl, Claus

2012-11-01

80

Strongly enhanced spin squeezing via quantum control.  

PubMed

We describe a new approach to spin squeezing based on a double-pass Faraday interaction between an optical probe and an optically dense atomic sample. A quantum eraser is used to remove residual spin-probe entanglement, thereby realizing a single-axis twisting unitary map on the collective spin. This interaction can be phase matched, resulting in exponential enhancement of squeezing as a function of optical density for times short compared to the decoherence time. In practice the scaling and peak squeezing depends on decoherence, technical loss, and noise. Including these imperfections, our model indicates that ?10 dB of squeezing should be achievable with laboratory parameters. PMID:21231167

Trail, Collin M; Jessen, Poul S; Deutsch, Ivan H

2010-11-01

81

Quantum Entanglement and Spin Control in Silicon Nanocrystal  

PubMed Central

Selective coherence control and electrically mediated exchange coupling of single electron spin between triplet and singlet states using numerically derived optimal control of proton pulses is demonstrated. We obtained spatial confinement below size of the Bohr radius for proton spin chain FWHM. Precise manipulation of individual spins and polarization of electron spin states are analyzed via proton induced emission and controlled population of energy shells in pure 29Si nanocrystal. Entangled quantum states of channeled proton trajectories are mapped in transverse and angular phase space of 29Si axial channel alignment in order to avoid transversal excitations. Proton density and proton energy as impact parameter functions are characterized in single particle density matrix via discretization of diagonal and nearest off-diagonal elements. We combined high field and low densities (1 MeV/92 nm) to create inseparable quantum state by superimposing the hyperpolarizationed proton spin chain with electron spin of 29Si. Quantum discretization of density of states (DOS) was performed by the Monte Carlo simulation method using numerical solutions of proton equations of motion. Distribution of gaussian coherent states is obtained by continuous modulation of individual spin phase and amplitude. Obtained results allow precise engineering and faithful mapping of spin states. This would provide the effective quantum key distribution (QKD) and transmission of quantum information over remote distances between quantum memory centers for scalable quantum communication network. Furthermore, obtained results give insights in application of channeled protons subatomic microscopy as a complete versatile scanning-probe system capable of both quantum engineering of charged particle states and characterization of quantum states below diffraction limit linear and in-depth resolution. PACS numbers: 03.65.Ud, 03.67.Bg, 61.85.+p, 67.30.hj PMID:23028884

Berec, Vesna

2012-01-01

82

Spin-orbit coupling and spin relaxation rate in singly charged pi-conjugated polymer chains  

NASA Astrophysics Data System (ADS)

In inorganic semiconductor spintronics the spin-diffusion length is usually limited by spin-orbit coupling. Here we examine the effect of spin-orbit coupling in organic spintronics. We consider singly charged pi-conjugated polymer chains. We show that the diagonal matrix elements for spin-orbit coupling are zero. Even the off-diagonal matrix elements are zero or negligibly small unless a twisted, non-planar polymer chain is considered. We calculate these matrix elements as a function of twist-angle using tight-binding wavefunctions. We show that time reversal symmetry prevents spin-orbit induced spin-precession and propose a phonon-assisted spin-flip process.

Rybicki, James; Nguyen, Tho Duc; Sheng, Yugang; Wohlgenannt, Markus

2010-03-01

83

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

PubMed Central

Magnetic field fluctuations arising from fundamental spins are ubiquitous in nanoscale biology, and are a rich source of information about the processes that generate them. However, the ability to detect the few spins involved without averaging over large ensembles has remained elusive. Here, we demonstrate the detection of gadolinium spin labels in an artificial cell membrane under ambient conditions using a single-spin nanodiamond sensor. Changes in the spin relaxation time of the sensor located in the lipid bilayer were optically detected and found to be sensitive to near-individual (4 ± 2) proximal gadolinium atomic labels. The detection of such small numbers of spins in a model biological setting, with projected detection times of 1 s [corresponding to a sensitivity of ?5 Gd spins per Hz1/2], opens a pathway for in situ nanoscale detection of dynamical processes in biology. PMID:23776230

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

2013-01-01

84

Nuclear magnetic resonance spectroscopy with single spin sensitivity  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

85

Nuclear magnetic resonance spectroscopy with single spin sensitivity  

PubMed Central

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

86

Electric control of the spin Hall effect by intervalley transitions.  

PubMed

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

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

2014-10-01

87

Electric control of the spin Hall effect by intervalley transitions  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

88

High-fidelity spin entanglement using optimal control.  

PubMed

Precise control of quantum systems is of fundamental importance in quantum information processing, quantum metrology and high-resolution spectroscopy. When scaling up quantum registers, several challenges arise: individual addressing of qubits while suppressing cross-talk, entangling distant nodes and decoupling unwanted interactions. Here we experimentally demonstrate optimal control of a prototype spin qubit system consisting of two proximal nitrogen-vacancy centres in diamond. Using engineered microwave pulses, we demonstrate single electron spin operations with a fidelity F?0.99. With additional dynamical decoupling techniques, we further realize high-quality, on-demand entangled states between two electron spins with F>0.82, mostly limited by the coherence time and imperfect initialization. Crosstalk in a crowded spectrum and unwanted dipolar couplings are simultaneously eliminated to a high extent. Finally, by high-fidelity entanglement swapping to nuclear spin quantum memory, we demonstrate nuclear spin entanglement over a length scale of 25 nm. This experiment underlines the importance of optimal control for scalable room temperature spin-based quantum information devices. PMID:24584174

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

2014-01-01

89

Light-Controlled Spin Filtering in Bacteriorhodopsin  

PubMed Central

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

2015-01-01

90

Coherent properties of single rare-earth spin qubits  

E-print Network

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

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

2014-05-20

91

Single shot NMR on single, dark nuclear spins  

E-print Network

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

92

Nanoscale magnetometry using a single spin system in diamond  

E-print Network

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

93

Attitude control of a spinning rocket via thrust vectoring  

SciTech Connect

Two controllers are developed to provide attitude control of a spinning rocket that has a thrust vectoring capability. The first controller has a single-input/single-output design that ignores the gyroscopic coupling between the control channels. The second controller has a multi-input/multi-output structure that is specifically intended to account for the gyroscopic coupling effects. A performance comparison between the two approached is conducted for a range of roll rates. Each controller is tested for the ability to track step commands, and for the amount of coupling impurity. Both controllers are developed via a linear-quadratic-regulator synthesis procedure, which is motivated by the multi-input/multi-output nature of second controller. Time responses and a singular value analysis are used to evaluate controller performance. This paper describes the development and comparison of two controllers that are designed to provide attitude control of a spinning rocket that is equipped with thrust vector control. 12 refs., 13 figs., 2 tabs.

White, J.E.

1990-12-19

94

Coherent detection of mechanical motion with a single spin qubit  

NASA Astrophysics Data System (ADS)

Mechanical systems can be influenced by a wide variety of extremely small forces, ranging from gravitational to optical, electrical, and magnetic. When mechanical resonators are scaled down to nanometer-scale dimensions, these forces can be harnessed to enable coupling to individual quantum systems. We present results showing that the coherent evolution of a single electronic spin associated with a Nitrogen Vacancy (NV) center in diamond can be coupled to the motion of a magnetized mechanical resonator. Specifically we use coherent manipulation of the spin to sense the driven and Brownian motion of the resonator under ambient conditions at a precision of 5 picometers. We discuss potential future applications of this technique including the detection of the zero-point fluctuations of a mechanical resonator, the realization of strong spin-phonon coupling at a single quantum level, and the implementation of quantum spin transducers.

Kolkowitz, Shimon; Unterreithmeier, Quirin; Jayich, Ania; Bennett, Steven; Rabl, Peter; Harris, Jack; Lukin, Mikhail

2012-06-01

95

Ultrafast optical control of entanglement between two quantum-dot spins  

Microsoft Academic Search

The interaction between two quantum bits enables the creation of entanglement, the two-particle correlations that are at the heart of quantum information science. In semiconductor quantum dots, much work has focused on demonstrating control over single spin qubits using optical techniques. However, optical control of two spin qubits remains a major challenge for scaling to a fully fledged quantum-information platform.

Danny Kim; Samuel G. Carter; Alex Greilich; Allan S. Bracker; Daniel Gammon

2011-01-01

96

High spin rate magnetic controller for nanosatellites  

NASA Astrophysics Data System (ADS)

This paper presents a study of a high rate closed-loop spin controller that uses only electromagnetic coils as actuators. The controller is able to perform spin rate control and simultaneously align the spin axis with the Earth's inertial reference frame. It is implemented, optimised and simulated for a 1-unit CubeSat ESTCube-1 to fulfil its mission requirements: spin the satellite up to 360 deg s-1 around the z-axis and align its spin axis with the Earth's polar axis with a pointing error of less than 3°. The attitude of the satellite is determined using a magnetic field vector, a Sun vector and angular velocity. It is estimated using an Unscented Kalman Filter and controlled using three electromagnetic coils. The algorithm is tested in a simulation environment that includes models of space environment and environmental disturbances, sensor and actuator emulation, attitude estimation, and a model to simulate the time delay caused by on-board calculations. In addition to the normal operation mode, analyses of reduced satellite functionality are performed: significant errors of attitude estimation due to non-operational Sun sensors; and limited actuator functionality due to two non-operational coils. A hardware-in-the-loop test is also performed to verify on-board software.

Slavinskis, A.; Kvell, U.; Kulu, E.; Sünter, I.; Kuuste, H.; Lätt, S.; Voormansik, K.; Noorma, M.

2014-02-01

97

Cavity Control in a Single-Electron Quantum Cyclotron  

E-print Network

Cavity Control in a Single-Electron Quantum Cyclotron An Improved Measurement of the Electron ­ Colloquium The Quantum Cyclotron · Single electron · Resolve lowest cyclotron and spin states via QND? Frequency! B #12;Hanneke MPPL 2010 ­ Colloquium Experimenter's g · The cyclotron is an anharmonic oscillator

Hanneke, David

98

Datta-Das transistor with enhanced spin control  

NASA Astrophysics Data System (ADS)

We consider a two-channel spin transistor with weak spin-orbit induced interband coupling. We show that the coherent transfer of carriers between the coupled channels gives rise to an additional spin rotation. We calculate the corresponding spin-resolved current in a Datta-Das geometry and show that a weak interband mixing leads to enhanced spin control.

Egues, J. Carlos; Burkard, Guido; Loss, Daniel

2003-04-01

99

Nanomagnetism: Spin doctors play with single electrons  

NASA Astrophysics Data System (ADS)

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

Erwin, Steven C.

2006-11-01

100

Excited-state spectroscopy using single-spin manipulation in diamond  

E-print Network

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

101

Single-Spin Asymmetries and Transversity in QCD  

SciTech Connect

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

Brodsky, S.J.; /SLAC

2005-12-14

102

Dynamic polarization of single nuclear spins by optical pumping of NV color centers in diamond at room temperature  

E-print Network

We report a versatile method to efficiently polarize single nuclear spins in diamond, which is based on optical pumping of a single NV color center and mediated by a level-anti crossing in its excited state. A nuclear spin polarization higher than 98% is achieved at room temperature for the 15N nuclear spin associated to the NV center, corresponding to $\\mu$K effective nuclear spin temperature. We then show simultaneous deterministic initialization of two nuclear spins (13C and 15N) in close vicinity to a NV defect. Such robust control of nuclear spin states is a key ingredient for further scaling up of nuclear-spin based quantum registers in diamond.

V. Jacques; P. Neumann; J. Beck; M. Markham; D. Twitchen; J. Meijer; F. Kaiser; G. Balasubramanian; F. Jelezko; J. Wrachtrup

2009-02-10

103

Optically and electrically controlled polariton spin transistor  

NASA Astrophysics Data System (ADS)

We propose two schemes of a spin-optronic device, optical analog of Datta and Das spin transistor for the electrons. The role of ferromagnetic contacts is played by one-dimensional polariton channels with strong TE-TM splitting. A symmetric two-dimensional trap plays a role of the nonmagnetic active region. The rotation of the polarization of the pulse in this region can be achieved either due to its interaction with a spatially confined polariton condensate created resonantly by a circular polarized laser, either due to the splitting between the two linear polarizations of the excitons, controlled electrically by use of metallic gate.

Shelykh, I. A.; Johne, R.; Solnyshkov, D. D.; Malpuech, G.

2010-10-01

104

Using nanoscale transistors to measure single donor spins in semiconductors  

SciTech Connect

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

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

2008-12-01

105

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

NASA Astrophysics Data System (ADS)

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

Simmons, Christie

2012-02-01

106

Entangled Absorption of a Single Photon with a Single Spin in Diamond  

NASA Astrophysics Data System (ADS)

Quantum entanglement, a key resource for quantum information science, is inherent in a solid. It has been recently shown that entanglement between a single optical photon and a single spin qubit in a solid is generated via spontaneous emission. However, entanglement generation by measurement is rather essential for quantum operations. We here show that the physics behind the entangled emission can be time reversed to demonstrate entangled absorption mediated by an inherent spin-orbit entanglement in a single nitrogen vacancy center in diamond. Optical arbitrary spin state preparation and complete spin state tomography reveal the fidelity of the entangled absorption to be 95%. With the entangled emission and absorption of a photon, materials can be spontaneously entangled or swap their quantum state based on the quantum teleportation scheme.

Kosaka, Hideo; Niikura, Naeko

2015-02-01

107

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

NASA Astrophysics Data System (ADS)

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

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

2007-01-01

108

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

E-print Network

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 center 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 center. 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 center 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.

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

2014-06-10

109

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

PubMed Central

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

110

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

PubMed

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

111

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

112

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

PubMed Central

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

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

2012-01-01

113

Room temperature entanglement between distant single spins in diamond  

E-print Network

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

114

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

NASA Astrophysics Data System (ADS)

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

Mayhall, Nicholas J.; Head-Gordon, Martin

2014-10-01

115

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

PubMed

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

Mayhall, Nicholas J; Head-Gordon, Martin

2014-10-01

116

Switching of a Single Atomic Spin Induced by Spin Injection:. a Model Calculation  

NASA Astrophysics Data System (ADS)

Toward the manipulation of a single atomic spin, we theoretically study the switching of a localized quantum spin S = (Sx, Sy, Sz) induced by spin injection in electrode/S/electrode junctions. This S has a uniaxial anisotropy energy, - |D|Sz2, which shows the bistable potential between Sz = -S and S, with D being an anisotropy constant. Furthermore, S interacts with the atomic vibration. For the initial state of Sz = -S, we consider a situation in which up-spin electrons exhibit the spin-flip tunneling from the left electrode to the right one through an exchange interaction between the electron spin and S. Using the master equation approach, we investigate the time t dependence of the current I, the expectation value of Sz, , and that of the vibration quantum number, , of an S = 2 system, which corresponds to an Fe atom on CuN surface. The systems exhibit the switching or nonswitching depending on the transition probability due to spin-atomic vibration interaction within a period of 10 ns. In addition, the t dependence of I and is explained on the basis of and the probability distribution.

Kokado, S.; Harigaya, K.; Sakuma, A.

2009-06-01

117

Single-proton spin detection by diamond magnetometry.  

PubMed

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

118

Electrical Detection of Spin Pumping due to the Precessing Magnetization of a Single Ferromagnet  

E-print Network

Electrical Detection of Spin Pumping due to the Precessing Magnetization of a Single Ferromagnet M of spin pumping, using a lateral normal-metal/ferromagnet/normal- metal device, where a single ferromagnet in ferromagnetic resonance pumps spin-polarized electrons into the normal metal, resulting in spin accumulation

van der Wal, Caspar H.

119

Fast electron spin resonance controlled manipulation of spin injection into quantum dots  

SciTech Connect

In our spin-injection light-emitting diodes, electrons are spin-polarized in a semimagnetic ZnMnSe spin aligner and then injected into InGaAs quantum dots. The resulting electron spin state can be read out by measuring the circular polarization state of the emitted light. Here, we resonantly excite the Mn 3d electron spin system with microwave pulses and perform time-resolved measurements of the spin dynamics. We find that we are able to control the spin polarization of the injected electrons on a microsecond timescale. This electron spin resonance induced spin control could be one of the ingredients required to utilize the quantum dot electrons or the Mn spins as qubits.

Merz, Andreas, E-mail: andreas.merz@kit.edu; Siller, Jan; Schittny, Robert; Krämmer, Christoph; Kalt, Heinz; Hetterich, Michael [Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe (Germany)

2014-06-23

120

Photoelectron spin-polarization control in the topological insulator Bi2Se3.  

PubMed

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

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

2014-02-21

121

Coherent spin control by electromagnetic vacuum fluctuations  

SciTech Connect

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

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

2011-05-15

122

Strong driving of a single spin using arbitrarily polarized fields  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

123

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

PubMed

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

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

2011-09-30

124

Electrical control of spin in topological insulators  

NASA Astrophysics Data System (ADS)

All-electrical manipulation of electron spin in solids becomes a central issue of quantum information processing and quantum computing. The many previous proposals are based on spin-orbit interactions in semiconductors. Topological insulator, a strong spin-orbit coupling system, make it possible to control the spin transport electrically. Recent calculations proved that external electric fields can drive a HgTe quantum well from normal band insulator phase to topological insulator phase [1]. Since the topological edge states are robust against local perturbation, the controlling of edge states using local fields is a challenging task. We demonstrate that a p-n junction created electrically in HgTe quantum wells with inverted band structure exhibits interesting intraband and interband tunneling processes. We find a perfect intraband transmission for electrons injected perpendicularly to the interface of the p-n junction. The opacity and transparency of electrons through the p-n junction can be tuned by changing the incidence angle, the Fermi energy and the strength of the Rashba spin-orbit interaction (RSOI). The occurrence of a conductance plateau due to the formation of topological edge states in a quasi-one-dimensional p-n junction can be switched on and off by tuning the gate voltage. The spin orientation can be substantially rotated when the samples exhibit a moderately strong RSOI [2]. An electrical switching of the edge-state transport can also be realized using quantum point contacts in quantum spin Hall bars. The switch-on/off of the edge channel is caused by the finite size effect of the quantum point contact and therefore can be manipulated by tuning the voltage applied on the split gate [3,4]. The magnetic ions doped on the surface of 3D TI can be correlated through the helical electrons. The RKKY interaction mediated by the helical Dirac electrons consists of the Heisenberg-like, Ising-like, and Dzyaloshinskii-Moriya (DM)-like terms, which can be tuned by changing the gate voltage. It provides us a new way to control surface magnetism electrically. The gap opened by doped magnetic ions can lead to a short-range Bloembergen-Rowland interaction. The competition among the Heisenberg, Ising, and DM terms leads to rich spin configurations and an anomalous Hall effect on different lattices [4]. There are many proposals for quantum computation scheme are based on the spin in semiconductor quantum dots. Topological insulator quantum dots display a very different behavior with that of conventional semiconductor quantum dots [5]. In sharp contrast to conventional semiconductor quantum dots, the quantum states in the gap of the HgTe QD are fully spin-polarized and show ring-like density distributions near the boundary of the QD and optically dark. The persistent charge currents and magnetic moments, i.e., the Aharonov-Bohm effect, can be observed in such a QD structure. This feature offers us a practical way to detect these exotic ring-like edge states by using the SQUID technique. [0pt]Refs: [1] W. Yang, Kai Chang, and S. C. Zhang, Phys. Rev. Lett. 100, 056602 (2008); J. Li and Kai Chang, Appl. Phys. Lett. 95, 222110 (2009). [2] L. B. Zhang, Kai Chang, X. C. Xie, H. Buhmann and L. W. Molenkamp, New J. Phys. 12, 083058 (2010). [3] L. B. Zhang, F. Cheng, F. Zhai and Kai Chang, Phys. Rev. B 83 081402(R) (2011); Z. H. Wu, F. Zhai, F. M. Peeters, H. Q. Xu and Kai Chang, Phys, Rev. Lett. 106, 176802 (2011). [4] J. J. Zhu, D. X. Yao, S. C. Zhang, and Kai Chang, Phys. Rev. Lett. 106, 097201 (2011). [5] Kai Chang, and Wen-Kai Lou, Phys. Rev. Lett. 106, 206802 (2011).

Chang, Kai

2012-02-01

125

Cryogenic single-chip electron spin resonance detector.  

PubMed

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

126

Observing a Quantum Phase Transition by Measuring a Single Spin  

E-print Network

We show that the ground-state quantum correlations of an Ising model can be detected by monitoring the time evolution of a single spin alone, and that the critical point of a quantum phase transition is detected through a maximum of a suitably defined observable. A proposed implementation with trapped ions realizes an experimental probe of quantum phase transitions which is based on quantum correlations and scalable for large system sizes.

Manuel Gessner; Michael Ramm; Hartmut Haeffner; Andreas Buchleitner; Heinz-Peter Breuer

2014-08-11

127

Ultrafast terahertz spin dynamics: from phonon-induced spin order to coherent magnon control  

NASA Astrophysics Data System (ADS)

Ultrashort pulses in the terahertz (THz) spectral range allow us to study and control spin dynamics on time scales faster than a single oscillation cycle of light. In a first set of experiments, we harness an optically triggered coherent lattice vibration to induce a transient spin-density wave in BaFe2As2, the parent compound of pnictide superconductors. The time-dependent multi-THz response of the non-equilibrium phases shows that the ordering quasi-adiabatically follows a coherent lattice oscillation at a frequency as high as 5.5 THz. The results suggest important implications for unconventional superconductivity. In a second step, we utilize the magnetic field component of intense THz transients to directly switch on and off coherent spin waves in the antiferromagnetic nickel oxide NiO. A femtosecond optical probe traces the magnetic dynamics in the time domain and verifies that the THz field addresses spins selectively via Zeeman interaction. This concept provides a universal ultrafast handle on magnetic excitations in the electronic ground state.

Kim, K. W.; Porer, M.; Bernhard, C.; Demsar, J.; Pashkin, A.; Kampfrath, T.; Sell, A.; Wolf, M.; Leitenstorfer, A.; Huber, R.

2013-02-01

128

Homonuclear single transition correlation spectroscopy of rare spins  

NASA Astrophysics Data System (ADS)

An alternative approach for rare spin homonuclear correlation spectroscopy is proposed and examined, which does not involve double quantum evolution. It relies instead on double quantum filtration resulting in a set of single transitions. This is followed by evolution and zero quantum mixing, generating a diagonal suppressed, single transition correlation spectrum that attains an efficiency matching the bound on unitary coherence transfer, but in fact benefits from reduced relaxation losses. This generally results in modest signal intensity improvement in a given measurement time, compared to the most efficient INADEQUATE variant. Results on 13C are reported and confirm the expected behavior.

Ramesh, V.; George, C.; Chandrakumar, N.

2009-06-01

129

Ultrafast control of nuclear spins using only microwave pulses: towards switchable solid-state quantum gates  

E-print Network

We demonstrate the control of the alpha-proton nuclear spin, I=1/2, coupled to the stable radical CH(COOH)2, S=1/2, in a gamma-irradiated malonic acid single crystal using only microwave pulses. We show that, depending on the state of the electron spin mS=+/-1/2, the nuclear spin can be locked in a desired state or oscillate between mI=+1/2 and mI=-1/2 on the nanosecond time scale. This approach provides a fast and efficient way of controlling nuclear spin qubits and also enables the design of switchable spin-based quantum gates by addressing only the electron spin.

George Mitrikas; Yiannis Sanakis; Georgios Papavassiliou

2009-10-13

130

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

E-print Network

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

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

2014-10-09

131

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

NASA Astrophysics Data System (ADS)

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

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

2015-04-01

132

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

PubMed

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

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

2015-04-22

133

Electron spin resonance of nitrogen-vacancy defects embedded in single nanodiamonds in an ABEL trap.  

PubMed

Room temperature optically detected magnetic resonance of a single quantum object with nanoscale position control is an outstanding challenge in many areas, particularly in the life sciences. We introduce a novel approach to control the nitrogen-vacancy (NV) centers hosted in a single fluorescent nanodiamond (FND) for which an anti-Brownian electrokinetic trap (ABEL) performs the position control and an integrated radiofrequency (RF) circuit provides enhanced magnetic flux density for ensemble spin-state control simultaneously. We demonstrate static magnetic field sensing in platforms compatible with ABEL trap. With the advances in the synthesis and functionalization of stable arbitrarily small FNDs, we foresee the use of our device for the trapping and manipulation of single molecular-sized FNDs in aqueous solution. PMID:25111386

Kayci, Metin; Chang, Huan-Cheng; Radenovic, Aleksandra

2014-09-10

134

Fluorescence and spin properties of defects in single digit nanodiamonds.  

PubMed

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

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

2009-07-28

135

Transverse single spin asymmetry in hadronic ?c,b production  

NASA Astrophysics Data System (ADS)

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

Schäfer, Andreas; Zhou, Jian

2013-07-01

136

Giant Spin Hall Effect in Single Photon Plasmonics  

E-print Network

We show the existence of a very large spin Hall effect of light (SHEL) in single photon plasmonics based on spontaneous emission and the dipole-dipole interaction initiated energy transfer (FRET) on plasmonic platforms. The spin orbit coupling inherent in Maxwell equations is seen in the conversion of sigma + photon to sigma - photon. The FRET is mediated by the resonant surface plasmons and hence we find very large SHEL. We present explicit results for SHEL on both graphene and metal films. We also study how the splitting of the surface plasmon on a metal film affects the SHEL. In contrast to most other works which deal with SHEL as correction to the paraxial results, we consider SHEL in the near field of dipoles which are far from paraxial.

G. S. Agarwal; S. -A. Biehs

2012-12-24

137

Smooth optimal quantum control for robust solid state spin magnetometry  

E-print Network

Nitrogen-vacancy centers in diamond show great potential as magnetic, electric and thermal sensors which are naturally packaged in a bio-compatible material. In particular, NV-based magnetometers combine small sensor volumes with high sensitivities under ambient conditions. The practical operation of such sensors, however, requires advanced quantum control techniques that are robust with respect to experimental and material imperfections, control errors, and noise. Here, we present a novel approach that uses Floquet theory to efficiently generate smooth and simple quantum control pulses with tailored robustness properties. We verify their performance by applying them to a single NV center and by characterising the resulting quantum gate using quantum process tomography. We show how the sensitivity of NV-ensemble magnetometry schemes can be improved by up to two orders of magnitude by compensating for inhomogeneities in both the control field and the spin transition frequency. Our approach is ideally suited for a wide variety of quantum technologies requiring high-fidelity, robust control under tight bandwidth requirements, such as spin-ensemble based memories involving high-Q cavities.

Tobias Nöbauer; Andreas Angerer; Björn Bartels; Michael Trupke; Stefan Rotter; Jörg Schmiedmayer; Florian Mintert; Johannes Majer

2014-12-16

138

Weak Optical Measurements and Control of Atomic Spin Ensembles  

Microsoft Academic Search

Optical polarization spectroscopy is uniquely suited as a continuous, non-destructive probe of the quantum state of an atomic spin ensemble, and provides an attractive starting point for studies of quantum measurement and control. I will broadly consider what information about the spins can be accessed, and also what kinds of spin dynamics can be driven by the atom-probe interaction. I

Poul Jessen

2005-01-01

139

Mechanical Spin Control of Nitrogen-Vacancy Centers in Diamond  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

140

Half-metallic properties, single-spin negative differential resistance, and large single-spin Seebeck effects induced by chemical doping in zigzag-edged graphene nanoribbons  

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

141

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

E-print Network

Coherent control of the nitrogen-vacancy (NV) center in diamond's triplet spin state has traditionally been accomplished with resonant ac magnetic fields under the constraint of the magnetic dipole selection rule, which forbids direct control of the $|-1>\\leftrightarrow |+1>$ spin transition. We show that high-frequency stress resonant with the spin state splitting can coherently control NV center spins within this subspace. Using a bulk-mode mechanical microresonator fabricated from single-crystal diamond, we apply intense ac stress to the diamond substrate and observe mechanically driven Rabi oscillations between the $|-1>$ and $|+1>$ states of an NV center spin ensemble. Additionally, we measure the inhomogeneous spin dephasing time ($T_{2}^{*}$) of the spin ensemble using a mechanical Ramsey sequence and compare it to the dephasing times measured with a magnetic Ramsey sequence for each of the three spin qubit combinations available within the NV center ground state. These results demonstrate coherent spin driving with a mechanical resonator and could enable the creation of a phase-sensitive $\\Delta$-system within the NV center ground state.

E. R. MacQuarrie; T. A. Gosavi; A. M. Moehle; N. R. Jungwirth; S. A. Bhave; G. D. Fuchs

2014-12-03

142

Giant optical Faraday rotation induced by a single electron spin in a quantum dot: Applications to entangling remote spins via a single photon  

E-print Network

We propose a quantum non-demolition method - giant Faraday rotation - to detect a single electron spin in a quantum dot inside a microcavity where negatively-charged exciton strongly couples to the cavity mode. Left- and right-circularly polarized light reflected from the cavity feels different phase shifts due to cavity quantum electrodynamics and the optical spin selection rule. This yields giant and tunable Faraday rotation which can be easily detected experimentally. Based on this spin-detection technique, a scalable scheme to create an arbitrary amount of entanglement between two or more remote spins via a single photon is proposed.

C. Y. Hu; A. Young; J. L. O'Brien; J. G. Rarity

2008-03-08

143

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

144

Indirect Control of Antiferromagnetic Domain Walls with Spin Current  

Microsoft Academic Search

The indirect controlled displacement of an antiferromagnetic domain wall by a spin current is studied by Landau-Lifshitz-Gilbert spin dynamics. The antiferromagnetic domain wall can be shifted both by a spin-polarized tunnel current of a scanning tunneling microscope or by a current driven ferromagnetic domain wall in an exchange coupled antiferromagnetic-ferromagnetic layer system. The indirect control of antiferromagnetic domain walls opens

R. Wieser; E. Y. Vedmedenko; R. Wiesendanger

2011-01-01

145

Anti-Spin Control for Marine Propulsion Systems  

Microsoft Academic Search

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

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

146

Controlled Quantum State Transfer in a Spin Chain  

Microsoft Academic Search

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

Jiangbin Gong; Paul Brumer

2007-01-01

147

Controlled quantum-state transfer in a spin chain  

Microsoft Academic Search

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

Jiangbin Gong; Paul Brumer

2007-01-01

148

Active coning compensation for control of spinning flying vehicles  

Microsoft Academic Search

Many gun launched projectiles spin to maintain in-flight dynamic stability. This spinning often induces the gyroscopic phenomenon known as precession, or coning. Coning poses a problem for actively controlling the projectile. A control scheme is proposed that can compensate for the coning angle of the projectile and allow front-mounted canards to efficiently change the projectile flight path without reaching a

M. U. Salman; B. Chang

2010-01-01

149

Universal control and error correction in multi-qubit spin registers in diamond  

E-print Network

Quantum registers of nuclear spins coupled to electron spins of individual solid-state defects are a promising platform for quantum information processing. Pioneering experiments selected defects with favourably located nuclear spins having particularly strong hyperfine couplings. For progress towards large-scale applications, larger and deterministically available nuclear registers are highly desirable. Here we realize universal control over multi-qubit spin registers by harnessing abundant weakly coupled nuclear spins. We use the electron spin of a nitrogen-vacancy centre in diamond to selectively initialize, control and read out carbon-13 spins in the surrounding spin bath and construct high-fidelity single- and two-qubit gates. We exploit these new capabilities to implement a three-qubit quantum-error-correction protocol and demonstrate the robustness of the encoded state against applied errors. These results transform weakly coupled nuclear spins from a source of decoherence into a reliable resource, paving the way towards extended quantum networks and surface-code quantum computing based on multi-qubit nodes.

T. H. Taminiau; J. Cramer; T. van der Sar; V. V. Dobrovitski; R. Hanson

2013-09-26

150

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

PubMed

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

151

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

152

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

PubMed Central

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

153

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

SciTech Connect

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

154

Fuel-optimal angular momentum vector control for spinning and dual-spin spacecraft.  

NASA Technical Reports Server (NTRS)

The problem of fuel-optimal small-angle reorientation of the spin axis of a spinning or dual-spin spacecraft is examined. The results obtained show significant improvements over previously published optimization studies by virtue of the introduction of two innovations: (1) mass-explusion active control is utilized for angular momentum vector pointing only, with passive damping relied upon for stable vehicles to attenuate vehicle coning about the angular momentum vector, so that the task of the active controller changes from spin axis control to angular momentum vector control, and (2) several options are considered for type, number, and location of attitude control jets. The first of these considerations introduces a target set which is a smooth, two-dimensional linear manifold in the four-dimensional state space, whereas previous studies have adopted the origin as the target set. The second innovation amounts to consideration of a spectrum of control restraint sets.

Larson, V.; Likins, P.

1973-01-01

155

Indirect control of antiferromagnetic domain walls with spin current.  

PubMed

The indirect controlled displacement of an antiferromagnetic domain wall by a spin current is studied by Landau-Lifshitz-Gilbert spin dynamics. The antiferromagnetic domain wall can be shifted both by a spin-polarized tunnel current of a scanning tunneling microscope or by a current driven ferromagnetic domain wall in an exchange coupled antiferromagnetic-ferromagnetic layer system. The indirect control of antiferromagnetic domain walls opens up a new and promising direction for future spin device applications based on antiferromagnetic materials. PMID:21405493

Wieser, R; Vedmedenko, E Y; Wiesendanger, R

2011-02-11

156

Single-spin precessing gravitational waveform in closed form  

NASA Astrophysics Data System (ADS)

In coming years, gravitational-wave detectors should find black hole-neutron star (BH-NS) binaries, potentially coincident with astronomical phenomena like short gamma ray bursts. These binaries are expected to precess. Gravitational-wave science requires a tractable model for precessing binaries, to disentangle precession physics from other phenomena like modified strong field gravity, tidal deformability, or Hubble flow; and to measure compact object masses, spins, and alignments. Moreover, current searches for gravitational waves from compact binaries use templates where the binary does not precess and are ill-suited for detection of generic precessing sources. In this paper we provide a closed-form representation of the single-spin precessing waveform in the frequency domain by reorganizing the signal as a sum over harmonics, each of which resembles a nonprecessing waveform. This form enables simple analytic calculations of the Fisher matrix for use in template bank generation and coincidence metrics, and jump proposals to improve the efficiency of Markov chain Monte Carlo sampling. We have verified that for generic BH-NS binaries, our model agrees with the time-domain waveform to 2%. Straightforward extensions of the derivations outlined here (and provided in full online) allow higher accuracy and error estimates.

Lundgren, Andrew; O'Shaughnessy, R.

2014-02-01

157

Single-spin azimuthal asymmetry in exclusive electroproduction of ?+ mesons  

NASA Astrophysics Data System (ADS)

A single-spin asymmetry in the distribution of exclusively produced ?+ mesons azimuthally around the virtual photon direction relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off longitudinally polarized protons. Integrated over the experimental acceptance, the /sin? moment of the polarization asymmetry of the cross section is measured to be /-0.18+/-0.05(stat.)+/-0.02(syst.). The asymmetry is also studied as a function of the relevant kinematic variables, and its magnitude is found to grow with decreasing /x and increasing /-t and vanish at t-->tmin (where /x is the Bjorken scaling variable and /t is the squared four-momentum transferred to the nucleon).

HERMES Collaboration; Airapetian, A.; Akopov, N.; Akopov, Z.; Amarian, M.; Aschenauer, E. C.; Avakian, H.; Avakian, R.; Avetissian, A.; Avetissian, E.; Bailey, P.; Baturin, V.; Baumgarten, C.; Beckmann, M.; Belostotski, S.; Bernreuther, S.; Bianchi, N.; Böttcher, H.; Borissov, A.; Bouhali, O.; Bouwhuis, M.; Brack, J.; Brauksiepe, S.; Brüll, A.; Brunn, I.; Bulten, H. J.; Capitani, G. P.; Chumney, P.; Cisbani, E.; Ciullo, G.; Court, G. R.; Dalpiaz, P. F.; De Leo, R.; De Nardo, L.; De Sanctis, E.; De Schepper, D.; Devitsin, E.; de Witt Huberts, P. K. A.; Di Nezza, P.; Düren, M.; Ehrenfried, M.; Elbakian, G.; Ellinghaus, F.; Ely, J.; Fabbri, R.; Fantoni, A.; Fechtchenko, A.; Felawka, L.; Filippone, B. W.; Fischer, H.; Fox, B.; Franz, J.; Frullani, S.; Gärber, Y.; Garibaldi, F.; Garutti, E.; Gavrilov, G.; Gharibyan, V.; Graw, G.; Grebeniouk, O.; Green, P. W.; Greeniaus, L. G.; Gute, A.; Haeberli, W.; Hafidi, K.; Hartig, M.; Hasch, D.; Heesbeen, D.; Heinsius, F. H.; Henoch, M.; Hertenberger, R.; Hesselink, W. H. A.; Hofman, G.; Holler, Y.; Holt, R. J.; Hommez, B.; Iarygin, G.; Izotov, A.; Jackson, H. E.; Jgoun, A.; Jung, P.; Kaiser, R.; Kisselev, A.; Kitching, P.; Königsmann, K.; Kolster, H.; Korotkov, V.; Kotik, E.; Kozlov, V.; Krauss, B.; Krivokhijine, V. G.; Kyle, G.; Lagamba, L.; Laziev, A.; Lenisa, P.; Liebing, P.; Lindemann, T.; Lorenzon, W.; Maas, A.; Makins, N. C. R.; Marukyan, H.; Masoli, F.; McIlhany, K.; Meissner, F.; Menden, F.; Mexner, V.; Meyners, N.; Mikloukho, O.; Milner, R.; Muccifora, V.; Nagaitsev, A.; Nappi, E.; Naryshkin, Y.; Nass, A.; Negodaeva, K.; Nowak, W.-D.; Oganessyan, K.; O'Neill, T. G.; Owen, B. R.; Pate, S. F.; Podiatchev, S.; Potashov, S.; Potterveld, D. H.; Raithel, M.; Rakness, G.; Rappoport, V.; Redwine, R.; Reggiani, D.; Reimer, P.; Reolon, A. R.; Rith, K.; Robinson, D.; Rostomyan, A.; Ryckbosch, D.; Sakemi, Y.; Sanjiev, I.; Sato, F.; Savin, I.; Scarlett, C.; Schäfer, A.; Schill, C.; Schmidt, F.; Schnell, G.; Schüler, K. P.; Schwind, A.; Seibert, J.; Seitz, B.; Shibata, T.-A.; Shutov, V.; Simani, M. C.; Simon, A.; Sinram, K.; Steffens, E.; Steijger, J. J. M.; Stewart, J.; Stösslein, U.; Suetsugu, K.; Taroian, S.; Terkulov, A.; Tessarin, S.; Thomas, E.; Tipton, B.; Tytgat, M.; Urciuoli, G. M.; van den Brand, J. F. J.; van der Steenhoven, G.; van de Vyver, R.; Vetterli, M. C.; Vikhrov, V.; Vincter, M. G.; Visser, J.; Volmer, J.; Weiskopf, C.; Wendland, J.; Wilbert, J.; Wise, T.; Yen, S.; Yoneyama, S.; Zohrabian, H.

2002-05-01

158

Calculation of TMD Evolution for Transverse Single Spin Asymmetry Measurements  

SciTech Connect

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

159

Global fitting of single spin asymmetry: An attempt  

NASA Astrophysics Data System (ADS)

We present an attempt of global analysis of semi-inclusive deep inelastic scattering ?p???'?X data on single spin asymmetries and data on left-right asymmetry AN in p?p??X in order to simultaneously extract information on the Sivers function and the twist-three quark-gluon Efremov-Teryaev-Qiu-Sterman function. We explore different possibilities such as the node of the Sivers function in x or k? in order to explain “sign mismatch” between these functions. We show that ?± semi-inclusive deep inelastic scattering data and ?0 STAR data can be well described in a combined fit based on both the transverse momentum dependent and collinear twist-three factorization formalisms; however, ?± BRAHMS data are not described in a satisfactory way. This leaves the question open of a solution to the “sign mismatch.” Possible explanations are then discussed.

Kang, Zhong-Bo; Prokudin, Alexei

2012-04-01

160

Electric control of spin in monolayer WSe? field effect transistors.  

PubMed

We report first-principles theoretical investigations of quantum transport in a monolayer WSe2 field effect transistor (FET). Due to strong spin-orbit interaction (SOI) and the atomic structure of the two-dimensional lattice, monolayer WSe2 has an electronic structure that exhibits Zeeman-like up-down spin texture near the K and K' points of the Brillouin zone. In a FET, the gate electric field induces an extra, externally tunable SOI that re-orients the spins into a Rashba-like texture thereby realizing electric control of the spin. The conductance of FET is modulated by the spin texture, namely by if the spin orientation of the carrier after the gated channel region, matches or miss-matches that of the FET drain electrode. The carrier current I(?, s) in the FET is labelled by both the valley index and spin index, realizing valleytronics and spintronics in the same device. PMID:25287881

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

2014-10-31

161

DFT studies of spin-electric effects in single-molecule magnets without inversion symmetry  

Microsoft Academic Search

Recently [1] it has been proposed that in single-molecule magnets (SMMs) lacking inversion symmetry, a mechanism based on the interplay among quantum exchange, spin orbit interaction and chirality of the underlying spin texture, allows for an effective coupling between the spin states and an external electric field. This effect could represent a very efficient and fast way of manipulating the

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

2010-01-01

162

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

E-print Network

and manipulate the spin states is also required for spin based quantum information processing. Although optical detection techniques, such as optically detected electron spin resonance (ESR) seem very powerful in these contexts, multiple molecules in the focal...

Shin, Chang-Seok

2009-05-15

163

Coherent spin transport and suppression of spin relaxation in InSb nanowires with single subband occupancy at room temperature.  

PubMed

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

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

2014-11-12

164

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

SciTech Connect

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

165

Coherent control of single photon states  

E-print Network

We define a class of multi-mode single photon states suitable for quantum information applications. We show how standard amplitude modulation techniques may be used to control the pulse shape of single photon states.

G. J. Milburn

2007-02-12

166

Geometric control of quantum spin systems  

NASA Astrophysics Data System (ADS)

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

Moseley, Christopher G.

2004-08-01

167

Dual-spin attitude control for outer planet missions  

NASA Technical Reports Server (NTRS)

The applicability of dual-spin technology to a Jupiter orbiter with probe mission was investigated. Basic mission and system level attitude control requirements were established and preliminary mechanization and control concepts developed. A comprehensive 18-degree-of-freedom digital simulation was utilized extensively to establish control laws, study dynamic interactions, and determined key sensitivities. Fundamental system/subsystem constraints were identified, and the applicability of dual-spin technology to a Jupiter orbiter with probe mission was validated.

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

1977-01-01

168

Mapping spin coherence of a single rare-earth ion in a crystal onto a single photon polarization state  

E-print Network

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

169

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

170

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

PubMed

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

171

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

PubMed Central

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

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

2014-01-01

172

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

E-print Network

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

Leigh M. Norris

2014-10-01

173

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

PubMed Central

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

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

2013-01-01

174

Subriemannian geodesics and optimal control of spin systems  

Microsoft Academic Search

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

Navin Khaneja; Steffen Glaser; Roger Brockett

2002-01-01

175

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

NASA Astrophysics Data System (ADS)

Large atomic ensembles interacting with light are one of the most promising platforms for quantum information processing. In the past decade, novel applications for these systems have emerged in quantum communication, quantum computing, and metrology. Essential to all of these applications is the controllability of the atomic ensemble, which is facilitated by a strong coupling between the atoms and light. Non-classical spin squeezed states are a crucial step in attaining greater ensemble control. The degree of entanglement present in these states, furthermore, serves as a benchmark for the strength of the atom-light interaction. Outside the broader context of quantum information processing with atomic ensembles, spin squeezed states have applications in metrology, where their quantum correlations can be harnessed to improve the precision of magnetometers and atomic clocks. This dissertation focuses upon the production of spin squeezed states in large ensembles of cold trapped alkali atoms interacting with optical fields. While most treatments of spin squeezing consider only the case in which the ensemble is composed of two level systems or qubits, we utilize the entire ground manifold of an alkali atom with hyperfine spin f greater or equal to 1/2, a qudit. Spin squeezing requires non-classical correlations between the constituent atomic spins, which are generated through the atoms' collective coupling to the light. Either through measurement or multiple interactions with the atoms, the light mediates an entangling interaction that produces quantum correlations. Because the spin squeezing treated in this dissertation ultimately originates from the coupling between the light and atoms, conventional approaches of improving this squeezing have focused on increasing the optical density of the ensemble. The greater number of internal degrees of freedom and the controllability of the spin-f ground hyperfine manifold enable novel methods of enhancing squeezing. In particular, we find that state preparation using control of the internal hyperfine spin increases the entangling power of squeezing protocols when f >1/2. Post-processing of the ensemble using additional internal spin control converts this entanglement into metrologically useful spin squeezing. By employing a variation of the Holstein-Primakoff approximation, in which the collective spin observables of the atomic ensemble are treated as quadratures of a bosonic mode, we model entanglement generation, spin squeezing and the effects of internal spin control. The Holstein-Primakoff formalism also enables us to take into account the decoherence of the ensemble due to optical pumping. While most works ignore or treat optical pumping phenomenologically, we employ a master equation derived from first principles. Our analysis shows that state preparation and the hyperfine spin size have a substantial impact upon both the generation of spin squeezing and the decoherence of the ensemble. Through a numerical search, we determine state preparations that enhance squeezing protocols while remaining robust to optical pumping. Finally, most work on spin squeezing in atomic ensembles has treated the light as a plane wave that couples identically to all atoms. In the final part of this dissertation, we go beyond the customary plane wave approximation on the light and employ focused paraxial beams, which are more efficiently mode matched to the radiation pattern of the atomic ensemble. The mathematical formalism and the internal spin control techniques that we applied in the plane wave case are generalized to accommodate the non-homogeneous paraxial probe. We find the optimal geometries of the atomic ensemble and the probe for mode matching and generation of spin squeezing.

Norris, Leigh Morgan

176

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

NASA Astrophysics Data System (ADS)

Large atomic ensembles interacting with light are one of the most promising platforms for quantum information processing. In the past decade, novel applications for these systems have emerged in quantum communication, quantum computing, and metrology. Essential to all of these applications is the controllability of the atomic ensemble, which is facilitated by a strong coupling between the atoms and light. Non-classical spin squeezed states are a crucial step in attaining greater ensemble control. The degree of entanglement present in these states, furthermore, serves as a benchmark for the strength of the atom-light interaction. Outside the broader context of quantum information processing with atomic ensembles, spin squeezed states have applications in metrology, where their quantum correlations can be harnessed to improve the precision of magnetometers and atomic clocks. This dissertation focuses upon the production of spin squeezed states in large ensembles of cold trapped alkali atoms interacting with optical fields. While most treatments of spin squeezing consider only the case in which the ensemble is composed of two level systems or qubits, we utilize the entire ground manifold of an alkali atom with hyperfine spin f greater than or equal to 1/2, a qudit. Spin squeezing requires non-classical correlations between the constituent atomic spins, which are generated through the atoms' collective coupling to the light. Either through measurement or multiple interactions with the atoms, the light mediates an entangling interaction that produces quantum correlations. Because the spin squeezing treated in this dissertation ultimately originates from the coupling between the light and atoms, conventional approaches of improving this squeezing have focused on increasing the optical density of the ensemble. The greater number of internal degrees of freedom and the controllability of the spin-f ground hyperfine manifold enable novel methods of enhancing squeezing. In particular, we find that state preparation using control of the internal hyperfine spin increases the entangling power of squeezing protocols when f>1/2. Post-processing of the ensemble using additional internal spin control converts this entanglement into metrologically useful spin squeezing. By employing a variation of the Holstein-Primakoff approximation, in which the collective spin observables of the atomic ensemble are treated as quadratures of a bosonic mode, we model entanglement generation, spin squeezing and the effects of internal spin control. The Holstein-Primakoff formalism also enables us to take into account the decoherence of the ensemble due to optical pumping. While most works ignore or treat optical pumping phenomenologically, we employ a master equation derived from first principles. Our analysis shows that state preparation and the hyperfine spin size have a substantial impact upon both the generation of spin squeezing and the decoherence of the ensemble. Through a numerical search, we determine state preparations that enhance squeezing protocols while remaining robust to optical pumping. Finally, most work on spin squeezing in atomic ensembles has treated the light as a plane wave that couples identically to all atoms. In the final part of this dissertation, we go beyond the customary plane wave approximation on the light and employ focused paraxial beams, which are more efficiently mode matched to the radiation pattern of the atomic ensemble. The mathematical formalism and the internal spin control techniques that we applied in the plane wave case are generalized to accommodate the non-homogeneous paraxial probe. We find the optimal geometries of the atomic ensemble and the probe for mode matching and generation of spin squeezing.

Norris, Leigh Morgan

177

Spin Solitons and Quantum Control of Spin Chain Dynamics  

Microsoft Academic Search

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

Navin Khaneja; Steffen J. Glaser

2002-01-01

178

Controllable spin transport in dual-gated silicene  

NASA Astrophysics Data System (ADS)

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

Wang, Yu; Lou, Yiyi

2014-07-01

179

Electron spin echo and spin relaxation of low-symmetry Mn(2+)-complexes in ammonium oxalate monohydrate single crystal.  

PubMed

Pulse EPR experiments were performed on low concentration Mn(2+) ions in ammonium oxalate monohydrate single crystals at X-band, in the temperature range 4.2-60K at crystal orientation close to the D-tensor z-axis. Hyperfine lines of the resolved spin transitions were selectively excited by short nanosecond pulses. Electron spin echo signal was not observed for the low spin transition (+5/2?+3/2) suggesting a magnetic field threshold for the echo excitation. Echo appears for higher spin transitions with amplitude, which grows with magnetic field. Opposite behavior displays amplitude of echo decay modulations, which is maximal at low field and negligible for high field spin transitions. Electron spin-lattice relaxation was measured by the pulse saturation method. After the critical analysis of possible relaxation processes it was concluded that the relaxation is governed by Raman T(7)-process. The relaxation is the same for all spin transitions except the lowest temperatures (below 20K) where the high field transitions (-3/2?-1/2) and (-5/2?-3/2) have a slower relaxation rate. Electron spin echo dephasing is produced by electron spectral diffusion mainly, with a small contribution from instantaneous diffusion for all spin transitions. For the highest field transition (-5/2?-3/2) an additional contribution from nuclear spectral diffusion appears with resonance type enhancement at low temperatures. PMID:25064270

Hoffmann, Stanis?aw K; Lijewski, Stefan; Goslar, Janina; Mielniczek-Brzóska, Ewa

2014-09-01

180

Photonic transport control by spin-optical disordered metasurface  

E-print Network

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

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

2014-01-01

181

Active control of magnetoresistance of organic spin valves using ferroelectricity  

PubMed Central

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

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

2014-01-01

182

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

NASA Astrophysics Data System (ADS)

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 N14 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.

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

2014-07-01

183

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

PubMed

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

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

2015-03-01

184

Nanoscale magnetic imaging of a single electron spin under ambient conditions  

E-print Network

The detection of ensembles of spins under ambient conditions has revolutionized the biological, chemical, and physical sciences through magnetic resonance imaging and nuclear magnetic resonance. Pushing sensing capabilities to the individual-spin level would enable unprecedented applications such as single molecule structural imaging; however, the weak magnetic fields from single spins are undetectable by conventional far-field resonance techniques. In recent years, there has been a considerable effort to develop nanoscale scanning magnetometers, which are able to measure fewer spins by bringing the sensor in close proximity to its target. The most sensitive of these magnetometers generally require low temperatures for operation, but measuring under ambient conditions (standard temperature and pressure) is critical for many imaging applications, particularly in biological systems. Here we demonstrate detection and nanoscale imaging of the magnetic field from a single electron spin under ambient conditions using a scanning nitrogen-vacancy (NV) magnetometer. Real-space, quantitative magnetic-field images are obtained by deterministically scanning our NV magnetometer 50 nanometers above a target electron spin, while measuring the local magnetic field using dynamically decoupled magnetometry protocols. This single-spin detection capability could enable single-spin magnetic resonance imaging of electron spins on the nano- and atomic scales and opens the door for unique applications such as mechanical quantum state transfer.

M. S. Grinolds; S. Hong; P. Maletinsky; L. Luan; M. D. Lukin; R. L. Walsworth; A. Yacoby

2012-09-02

185

Spin-controlled plasmonics via optical Rashba effect  

SciTech Connect

Observation of the optical Rashba effect in plasmonics is reported. Polarization helicity degeneracy removal, associated with the inversion symmetry violation, is attributed to the surface symmetry design via anisotropic nanoantennas with space-variant orientations. By utilizing the Rashba-induced momentum in a nanoscale kagome metastructure, we demonstrated a spin-based surface plasmon multidirectional excitation under a normal-incidence illumination. The spin-controlled plasmonics via spinoptical metasurfaces provides a route for spin-based surface-integrated photonic nanodevices and light-matter interaction control, extending the light manipulation capabilities.

Shitrit, Nir; Yulevich, Igor; Kleiner, Vladimir; Hasman, Erez, E-mail: mehasman@technion.ac.il [Micro and Nanooptics Laboratory, Faculty of Mechanical Engineering, and Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa 32000 (Israel)] [Micro and Nanooptics Laboratory, Faculty of Mechanical Engineering, and Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa 32000 (Israel)

2013-11-18

186

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

187

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

PubMed Central

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

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

2014-01-01

188

Spin-path entanglement in single-neutron interferometer experiments  

SciTech Connect

There are two powerful arguments against the possibility of extending quantum mechanics (QM) into a more fundamental theory yielding a deterministic description of nature. One is the experimental violation of Bell inequalities, which discards local hidden-variable theories as a possible extension to QM. The other is the Kochen-Specker (KS) theorem, which stresses the incompatibility of QM with a larger class of hidden-variable theories, known as noncontextual hidden-variable theories. We performed experiments with neutron interferometer, which exploits spin-path entanglements in single neutrons. A Bell-like state is generated to demonstrate a violation of the Bell-like inequality and phenomena in accordance with KS theorem: both experiments study quantum contextuality and show clear evidence of the incompatibility of noncontextual hidden variable theories with QM. The value S = 2.202{+-}0.007 Neither-Less-Than-Nor-Equal-To 2 is obtained in the new measurement of the Bell-like inequality, which shows a larger violation than the previous measurement. For the study of KS theorem, the obtained violation 2.291{+-}0.008 Neither-Less-Than-Nor-Equal-To 1 clearly shows that quantum mechanical predictions cannot be reproduced by noncontextual hidden variable theories.

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

2011-09-23

189

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

190

Indirect control of spin precession by electric field via spin-orbit coupling  

E-print Network

The spin-orbit coupling (SOC) can mediate electric-dipole spin resonance (EDSR) in an a.c. electric field. In this letter, the EDSR is essentially understood as an spin precession under an effective a.c. magnetic field induced by the SOC in the reference frame, which is exactly following the classical trajectory of the electron and obtained by applying a quantum linear coordinate transformation. With this observation for one-dimensional (1D) case, we find a upper limit for the spin-flipping speed in the EDSR-based control of spin, which is given by the accessible data from the current experiment. For two-dimensional case, the azimuthal dependence of the effective magnetic field can be used to measure the ratio of the Rashba and Dresselhause SOC strengths.

Li-Ping Yang; C. P. Sun

2014-08-18

191

Spin vector control of a spinning space station  

NASA Technical Reports Server (NTRS)

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

Hendricks, T.

1971-01-01

192

Magnetic attitude control of near earth spinning satellites  

Microsoft Academic Search

Magnetic attitude control systems were employed in several satellite programs due to their salient features like simplicity in construction, absence of moving parts, less power and space requirements and less weight. A control law suitable for keeping the spin axis of the satellite perpendicular to the plane of a near circular orbit was derived, and a control scheme incorporating the

S. Rajaram; P. S. Goel

1977-01-01

193

Spin-controlled mechanics in nanoelectromechanical systems  

NASA Astrophysics Data System (ADS)

We consider a dc-electronic tunneling transport through a carbon nanotube suspended between normal-metal source and arbitrarily spin-polarized drain lead in the presence of an external magnetic field. We show that magnetomotive coupling between electrical current through the nanotube and its mechanical vibrations may lead to an electromechanical instability and give an onset of self-excited mechanical vibrations depending on spin polarization of the drain lead and frequency of vibrations. The self-excitation mechanism is based on correlation between the occupancy of quantized Zeeman-split electronic states in the nanotube and the direction of velocity of its mechanical motion. It is an effective gating effect by the presence of electron in the spin state which, through the Coulomb blockade, permits tunneling of electron to the drain predominantly only during a particular phase of mechanical vibration thus coherently changing mechanical momentum and leading into instability if mechanical damping is overcome.

Radi?, D.

2015-03-01

194

Electric control of spin injection into a ferroelectric semiconductor.  

PubMed

Electric-field control of spin-dependent properties has become one of the most attractive phenomena in modern materials research due to the promise of new device functionalities. One of the paradigms in this approach is to electrically toggle the spin polarization of carriers injected into a semiconductor using ferroelectric polarization as a control parameter. Using first-principles density-functional calculations, we explore the effect of ferroelectric polarization of electron-doped BaTiO_{3} (n-BaTiO_{3}) on the spin-polarized transmission across the SrRuO_{3}/n-BaTiO_{3}(001) interface. Our study reveals that, in this system, the interface transmission is negatively spin polarized and that ferroelectric polarization reversal leads to a change in the transport spin polarization from -65% to -98%. Analytical model calculations demonstrate that this is a general effect for ferromagnetic-metal-ferroelectric-semiconductor systems and, furthermore, that ferroelectric modulation can even reverse the sign of spin polarization. The predicted effect provides a nonvolatile mechanism to electrically control spin injection in semiconductor-based spintronics devices. PMID:25679900

Liu, Xiaohui; Burton, J D; Zhuravlev, M Ye; Tsymbal, Evgeny Y

2015-01-30

195

Electric Control of Spin Injection into a Ferroelectric Semiconductor  

NASA Astrophysics Data System (ADS)

Electric-field control of spin-dependent properties has become one of the most attractive phenomena in modern materials research due to the promise of new device functionalities. One of the paradigms in this approach is to electrically toggle the spin polarization of carriers injected into a semiconductor using ferroelectric polarization as a control parameter. Using first-principles density-functional calculations, we explore the effect of ferroelectric polarization of electron-doped BaTiO3 (n -BaTiO3 ) on the spin-polarized transmission across the SrRuO3/n -BaTiO3(001 ) interface. Our study reveals that, in this system, the interface transmission is negatively spin polarized and that ferroelectric polarization reversal leads to a change in the transport spin polarization from -65 % to -98 % . Analytical model calculations demonstrate that this is a general effect for ferromagnetic-metal-ferroelectric-semiconductor systems and, furthermore, that ferroelectric modulation can even reverse the sign of spin polarization. The predicted effect provides a nonvolatile mechanism to electrically control spin injection in semiconductor-based spintronics devices.

Liu, Xiaohui; Burton, J. D.; Zhuravlev, M. Ye.; Tsymbal, Evgeny Y.

2015-01-01

196

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

PubMed Central

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

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

2012-01-01

197

Probing Johnson noise and ballistic transport in normal metals with a single-spin qubit  

NASA Astrophysics Data System (ADS)

Thermally induced electrical currents, known as Johnson noise, cause fluctuating electric and magnetic fields in proximity to a conductor. These fluctuations are intrinsically related to the conductivity of the metal. We use single-spin qubits associated with nitrogen-vacancy centers in diamond to probe Johnson noise in the vicinity of conductive silver films. Measurements of polycrystalline silver films over a range of distances (20 to 200 nanometers) and temperatures (10 to 300 kelvin) are consistent with the classically expected behavior of the magnetic fluctuations. However, we find that Johnson noise is markedly suppressed next to single-crystal films, indicative of a substantial deviation from Ohm’s law at length scales below the electron mean free path. Our results are consistent with a generalized model that accounts for the ballistic motion of electrons in the metal, indicating that under the appropriate conditions, nearby electrodes may be used for controlling nanoscale optoelectronic, atomic, and solid-state quantum systems.

Kolkowitz, S.; Safira, A.; High, A. A.; Devlin, R. C.; Choi, S.; Unterreithmeier, Q. P.; Patterson, D.; Zibrov, A. S.; Manucharyan, V. E.; Park, H.; Lukin, M. D.

2015-03-01

198

Spin Models for Packet Routing Control in Computer Networks  

NASA Astrophysics Data System (ADS)

We investigate packet flow in computer networks within the framework of statistical physics by using numerical simulations. As mathematical models for packet routing, we present a spin model with lattice gas spins and the one with Ising spins. Then we propose dynamic programming for optimal routing control of packet flow by using the two spin models. This is a kind of goal-directed learning for taking into account of time-dependent environment for the packets. Next we investigate a congestion problem by using the model with lattice gas spins when the packets are not sent to nodes at which their buffers are already full up with packets. Since we have found serious congestion in the packet flow, we then propose reinforcement learning for avoiding the congestion and have performed simulations on several networks including small world networks, scale free networks and so on.

Horiguchi, T.

199

Gate-controlled electron spins in quantum dots  

NASA Astrophysics Data System (ADS)

In this paper we study the properties of anisotropic semiconductor quantum dots (QDs) formed in the conduction band in the presence of the magnetic field. The Kane-type model is formulated and is analyzed by using both analytical and finite element techniques. Among other things, we demonstrate that in such quantum dots, the electron spin states in the phonon-induced spin-flip rate can be manipulated with the application of externally applied anisotropic gate potentials. More precisely, such potentials enhance the spin flip rates and reduce the level crossing points to lower quantum dot radii. This happens due to the suppression of the g-factor towards bulk crystal. We conclude that the phonon induced spin-flip rate can be controlled through the application of spin-orbit coupling. Numerical examples are shown to demonstrate these findings.

Prabhakar, Sanjay; Melnik, Roderick; Bonilla, Luis L.

2013-12-01

200

Gate-controlled electron spins in quantum dots  

SciTech Connect

In this paper we study the properties of anisotropic semiconductor quantum dots (QDs) formed in the conduction band in the presence of the magnetic field. The Kane-type model is formulated and is analyzed by using both analytical and finite element techniques. Among other things, we demonstrate that in such quantum dots, the electron spin states in the phonon-induced spin-flip rate can be manipulated with the application of externally applied anisotropic gate potentials. More precisely, such potentials enhance the spin flip rates and reduce the level crossing points to lower quantum dot radii. This happens due to the suppression of the g-factor towards bulk crystal. We conclude that the phonon induced spin-flip rate can be controlled through the application of spin-orbit coupling. Numerical examples are shown to demonstrate these findings.

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

2013-12-16

201

Polarization-Controlled Single Photons  

Microsoft Academic Search

Vacuum-stimulated Raman transitions are driven between two magnetic substates\\u000aof a rubidium-87 atom strongly coupled to an optical cavity. A magnetic field\\u000alifts the degeneracy of these states, and the atom is alternately exposed to\\u000alaser pulses of two different frequencies. This produces a stream of single\\u000aphotons with alternating circular polarization in a predetermined\\u000aspatio-temporal mode. MHz repetition rates

T. Wilk; S. C. Webster; H. P. Specht; G. Rempe; A. Kuhn

2007-01-01

202

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

E-print Network

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

Ian Harry; Stephen Fairhurst

2011-01-07

203

Spin-related thermoelectric conversion in lateral spin-valve devices with single-crystalline Co2FeSi electrodes  

NASA Astrophysics Data System (ADS)

We demonstrate the conversion between a heat current and a spin current in Cu-based lateral spin valves (LSVs) with single-crystalline Co2FeSi (CFS) electrodes. We can observe the thermally induced spin injection from CFS into Cu resulting from the spin-dependent Seebeck effect, and the heat current generated by the spin-dependent Peltier effect can be detected even in the LSV structures. This study is an important step toward understanding heat-spin conversion in single-crystalline materials with various electronic band structures.

Yamasaki, Kento; Oki, Soichiro; Yamada, Shinya; Kanashima, Takeshi; Hamaya, Kohei

2015-04-01

204

Detection of single electron spin resonance in a double quantum dota)  

NASA Astrophysics Data System (ADS)

Spin-dependent transport measurements through a double quantum dot are a valuable tool for detecting both the coherent evolution of the spin state of a single electron, as well as the hybridization of two-electron spin states. In this article, we discuss a model that describes the transport cycle in this regime, including the effects of an oscillating magnetic field (causing electron spin resonance) and the effective nuclear fields on the spin states in the two dots. We numerically calculate the current flow due to the induced spin flips via electron spin resonance, and we study the detector efficiency for a range of parameters. The experimental data are compared with the model and we find a reasonable agreement.

Koppens, F. H. L.; Buizert, C.; Vink, I. T.; Nowack, K. C.; Meunier, T.; Kouwenhoven, L. P.; Vandersypen, L. M. K.

2007-04-01

205

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

206

Polarization-controlled single photons  

E-print Network

Vacuum-stimulated Raman transitions are driven between two magnetic substates of a rubidium-87 atom strongly coupled to an optical cavity. A magnetic field lifts the degeneracy of these states, and the atom is alternately exposed to laser pulses of two different frequencies. This produces a stream of single photons with alternating circular polarization in a predetermined spatio-temporal mode. MHz repetition rates are possible as no recycling of the atom between photon generations is required. Photon indistinguishability is tested by time-resolved two-photon interference.

Wilk, T; Rempe, G; Specht, H P; Webster, S C

2006-01-01

207

Polarization-Controlled Single Photons  

NASA Astrophysics Data System (ADS)

Vacuum-stimulated Raman transitions are driven between two magnetic substates of a Rb87 atom strongly coupled to an optical cavity. A magnetic field lifts the degeneracy of these states, and the atom is alternately exposed to laser pulses of two different frequencies. This produces a stream of single photons with alternating circular polarization in a predetermined spatiotemporal mode. MHz repetition rates are possible as no recycling of the atom between photon generations is required. Photon indistinguishability is tested by time-resolved two-photon interference.

Wilk, T.; Webster, S. C.; Specht, H. P.; Rempe, G.; Kuhn, A.

2007-02-01

208

Polarization-controlled single photons  

E-print Network

Vacuum-stimulated Raman transitions are driven between two magnetic substates of a rubidium-87 atom strongly coupled to an optical cavity. A magnetic field lifts the degeneracy of these states, and the atom is alternately exposed to laser pulses of two different frequencies. This produces a stream of single photons with alternating circular polarization in a predetermined spatio-temporal mode. MHz repetition rates are possible as no recycling of the atom between photon generations is required. Photon indistinguishability is tested by time-resolved two-photon interference.

T. Wilk; S. C. Webster; H. P. Specht; G. Rempe; A. Kuhn

2006-10-26

209

Polarization-controlled single photons.  

PubMed

Vacuum-stimulated Raman transitions are driven between two magnetic substates of a 87Rb atom strongly coupled to an optical cavity. A magnetic field lifts the degeneracy of these states, and the atom is alternately exposed to laser pulses of two different frequencies. This produces a stream of single photons with alternating circular polarization in a predetermined spatiotemporal mode. MHz repetition rates are possible as no recycling of the atom between photon generations is required. Photon indistinguishability is tested by time-resolved two-photon interference. PMID:17358938

Wilk, T; Webster, S C; Specht, H P; Rempe, G; Kuhn, A

2007-02-01

210

Coherent control of atomic spin currents in a double well  

NASA Astrophysics Data System (ADS)

We propose a method for controlling the atomic currents of a two-component Bose-Einstein condensate in a double well by applying an external field to the atoms in one of the potential wells. We study the ground-state properties of the system and show that the directions of spin currents and net-particle tunneling can be manipulated by adiabatically varying the coupling strength between the atoms and the field. This system can be used to study spin and tunneling phenomena across a wide range of interaction parameters. In addition, spin-squeezed states can be generated. It is useful for quantum information processing and quantum metrology.

Ng, H. T.; Chu, Shih-I.

2012-02-01

211

Floquet control on quantum dissipation in spin chain  

E-print Network

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

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

2014-08-01

212

Quantum gates controlled by spin chain soliton excitations  

SciTech Connect

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

Cuccoli, Alessandro, E-mail: cuccoli@fi.infn.it [Dipartimento di Fisica e Astronomia, Università di Firenze, I-50019 Sesto Fiorentino (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, I-50019 Sesto Fiorentino (Italy); Nuzzi, Davide [Dipartimento di Fisica e Astronomia, Università di Firenze, I-50019 Sesto Fiorentino (Italy); Vaia, Ruggero [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, I-50019 Sesto Fiorentino (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, I-50019 Sesto Fiorentino (Italy); Verrucchi, Paola [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, I-50019 Sesto Fiorentino (Italy); Dipartimento di Fisica e Astronomia, Università di Firenze, I-50019 Sesto Fiorentino (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, I-50019 Sesto Fiorentino (Italy)

2014-05-07

213

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

NASA Astrophysics Data System (ADS)

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

de Greve, Kristiaan

2012-02-01

214

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

NASA Astrophysics Data System (ADS)

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

Tokura, Yasuhiro

2012-02-01

215

Stars Can't Spin Out of Control (Artist's Animation)  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Click on the image for QuickTime Movie of Stars Can't Spin Out of Control

This artist's animation demonstrates how a dusty planet-forming disk can slow down a whirling young star, essentially saving the star from spinning itself to death. Evidence for this phenomenon comes from NASA's Spitzer Space Telescope.

The movie begins by showing a developing star (red ball). The star is basically a giant ball of gas that is collapsing onto itself. As it shrinks, it spins faster and faster, like a skater folding in his or her arms. The green lines represent magnetic fields.

As gravity continues to pull matter inward, the star spins so fast, it starts to flatten out. The same principle applies to the planet Saturn, whose spin has caused it to be slightly squashed or oblate.

A forming star can theoretically whip around fast enough to overcome gravity and flatten itself into a state where it can no longer become a full-fledged star. But stars don't spin out of control, possibly because swirling disks of dust slow them down. Such disks can be found orbiting young stars, and are filled with dust that might ultimately stick together to form planets.

The second half of the animation demonstrates how a disk is thought to keep its star's speed in check. A developing star is shown twirling inside its disk. As it turns, its magnetic fields pass through the disk and get bogged down like a spoon in molasses. This locks the star's rotation to the slower-turning disk, so the star, while continuing to shrink, does not spin faster.

Spitzer found evidence for star-slowing disks in a survey of nearly 500 forming stars in the Orion nebula. It observed that slowly spinning stars are five times more likely to host disks than rapidly spinning stars.

2006-01-01

216

Ultrafast optical entanglement control between two quantum dot spins  

Microsoft Academic Search

Using continuous-wave lasers and picosecond optical pulses, we demonstrate initialization, single qubit gates, and two qubit gates in a system of two electron spins in separate tunnel-coupled InAs quantum dots. © 2011 Optical Society of America OCIS Codes: (270.5585) Quantum information and processing; (320.7130) Ultrafast processes in condensed matter, including semiconductors

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

2011-01-01

217

Temperature induced Spin Switching in SmFeO3 Single Crystal  

PubMed Central

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

218

Spin-resolved measurements of single molecular magnets on graphene  

NASA Astrophysics Data System (ADS)

The use of magnetic molecules opens a gateway to a flexible design of novel spintronic devices to store, manipulate, and read spin information at the nanoscale. Crucial is the precise knowledge of molecular properties at the interface towards an electrode. Progress in this field relies on resolving and understanding the physics at the relevant interfaces. In particular the role of individual molecular constituents and the impact of the atomic environment on molecular properties determine device relevant parameters, such as conductance and spin polarization. Recently, the incorporation of a graphene sheet to electronically decouple molecules from a ferromagnetic surface has been addressed by surface averaging high-resolution electron energy loss spectroscopy. Here, we applied spin-polarized scanning tunneling microscopy to resolve the physics of the molecule-graphene-ferromagnet interface. The analysis focuses on different phthalocyanine molecules adsorbed on cobalt-intercalated graphene on Ir(111). The phthalocyanine constitutes of an organic macrocyclic ligand and can be functionalized with various metal ions in order to modify, e.g. the molecular spin state. We will discuss the spin-dependent transport from magnetic surfaces through such molecules. In particular, the spin polarization of molecular frontier orbitals is resolved with sub-molecular spatial resolution and the variations in the lifetimes of different orbitals are discussed.

Brede, Jens; Decker, Regis; Schwoebel, Joerg; Bazarnik, Maciej; Wiesendanger, Roland

2013-03-01

219

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

SciTech Connect

A method to optically control a dark transition, for instance, the coupling between different spin states, is proposed. The control is achieved by manipulating the direction, amplitude, and duration of dynamic Stark shifts. Laser-driven spin switches can be prepared by conveniently generalizing different optical techniques, such as {pi}-pulse schemes and adiabatic passage schemes. The efficiency and robustness of the schemes is analyzed for both two-level and multilevel systems, implying quantum state selective wave packet transfer between states of different multiplicity.

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

2006-10-15

220

Spin-dependent Goos-Hänchen shift and spin beam splitter in gate-controllable ferromagnetic graphene  

NASA Astrophysics Data System (ADS)

The transmission and Goos-Hänchen (GH) shift for charge carriers in gate-controllable ferromagnetic graphene induced by ferromagnetic insulator are investigated theoretically. Numerical results demonstrate that spin-up and spin-down electrons exhibit remarkably different transmission and GH shifts. The spin-dependent GH shifts directly demonstrate the spin beam splitting effect, which can be controlled by the voltage of gate. We attribute the spin beam splitting effect to the combination of tunneling through potential barrier and Zeeman interaction from the magnetic field and the exchange proximity interaction between the ferromagnetic insulator and graphene. In view of the spin beam splitting effect and the spin-dependent GH shifts, the gate-controllable ferromagnetic graphene might be utilized to design spin beam splitter.

Wang, Y.; Liu, Y.; Wang, B.

2014-03-01

221

Spin valleytronics in silicene: Quantum spin Hall-quantum anomalous Hall insulators and single-valley semimetals  

NASA Astrophysics Data System (ADS)

Valley-based electronics, known as valleytronics, is one of the keys to breaking through to a new stage of electronics. The valley degree of freedom is ubiquitous in the honeycomb lattice system. The honeycomb lattice structure of silicon, called silicene, is a fascinating playground of valleytronics. We investigate topological phases of silicene by introducing different exchange fields on the A and B sites. There emerges a rich variety of topologically protected states, each of which has a characteristic spin-valley structure. The single Dirac-cone semimetal is such a state where one gap is closed while the other three gaps are open, evading the Nielsen-Ninomiya fermion-doubling problem. We have newly discovered a hybrid topological insulator named the quantum spin-quantum anomalous Hall insulator, where the quantum anomalous Hall effect occurs at one valley and the quantum spin Hall effect occurs at the other valley. Along its phase boundary, single-valley semimetals emerge, where only one of the two valleys is gapless with degenerated spins. These semimetals are also topologically protected because they appear in the interface of different topological insulators. Such a spin-valley-dependent physics will be observed by optical absorption or edge modes.

Ezawa, Motohiko

2013-04-01

222

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

E-print Network

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

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

2004-09-12

223

Transverse Single Spin and Azimuthal Asymmetries in Hadronic Collisions at STAR  

NASA Astrophysics Data System (ADS)

Hadronic collisions with transversely polarized protons are an important part of the quest to understand the transverse spin structure of the proton. Experiments at RHIC collected large datasets at center of mass energies of 200 GeV and 500 GeV, accessing a kinematic regime where factorization is expected to hold. The STAR detector at RHIC, due to its azimuthal symmetry, particle identification capabilities and large acceptance compared with other experiments with polarized protons, is in a unique position to study transverse spin phenomena in p + p?. This contribution will highlight measurements of transversity using di-hadron correlations, transverse single spin asymmetries in jets, measurements sensitive to the origins of the large single spin asymmetries measured in the forward direction, transverse spin asymmetries in W production, which are sensitive to modified universality effects of Sivers function as well as short and long-term upgrades at STAR.

Vossen, Anselm

2015-01-01

224

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

225

Control of spinning flexible spacecraft by modal synthesis  

NASA Technical Reports Server (NTRS)

A procedure is presented for the active control of a spinning flexible spacecraft. Such a system exhibits gyroscopic effects. The design of the controller is based on modal decomposition of the gyroscopic system. This modal decoupling procedure leads to a control mechanism implemented in modular form, which represents a distinct computational advantage over the control of the coupled system. Design procedures are demonstrated for two types of control algorithms, linear and nonlinear. The first represents classical linear feedback approach, and the second represents an application of on-off control, both types made feasible by the modal decomposition scheme.

Meirovitch, L.; Vanlandingham, H. F.; Oez, H.

1976-01-01

226

Sensing thermal motion of a mechanical resonator using a single spin qubit in diamond  

NASA Astrophysics Data System (ADS)

We present experimental results demonstrating the detection of the motion of a magnetized mechanical cantilever using a single spin qubit associated with a nitrogen-vacancy (NV) defect center in diamond. This setup is predicted to enable strong, coherent coupling between the NV electronic spin and the motion of the cantilever, allowing for the mechanical analog of cavity quantum electrodynamics [1]. To this end, we use the NV spin to detect both driven and thermal motion of a magnetic force microscope cantilever at room temperature, reading out the spin state optically using the spin-selective fluorescence of the NV. This method utilizes the high sensitivity of the NV spin precession to Zeeman shifts caused by the a.c. magnetic field induced by the motion of the cantilever. Finally, we discuss potential applications of our approach to the realization of quantum spin transducers using arrays of coupled spin-cantilever pairs [2]. 1. Rabl, P. et al. Strong magnetic coupling between an electronic spin qubit and a mechanical resonator. Physical Review B 79, 41302 (2009). 2. Rabl, P. et al. A quantum spin transducer based on nanoelectromechanical resonator arrays. Nature Physics 6, 602--608 (2010).

Kolkowitz, Shimon; Bleszynski Jayich, Ania; Rabl, Peter; Bennet, Steven; Unterreithmeier, Quirin; Harris, Jack; Lukin, Mikhail

2011-06-01

227

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

E-print Network

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.

228

Initial-state interactions and single-spin asymmetries in Drell-Yan processes  

NASA Astrophysics Data System (ADS)

We show that the initial-state interactions from gluon exchange between the incoming quark and the target spectator system lead to leading-twist single-spin asymmetries in the Drell-Yan process H1H2??? +? -X. The QCD initial-state interactions produce a T-odd spin-correlation S?H 2· P?H 1× Q? between the target spin and the virtual photon production plane which is not power-law suppressed in the Drell-Yan scaling limit at large photon virtuality Q2 at fixed xF. The single-spin asymmetry which arises from the initial-state interactions is not related to the target or projectile transversity distribution ?qH( x, Q). The origin of the single-spin asymmetry in ?p??? +? -X is a phase difference between two amplitudes coupling the proton target with J zp=± {1}/{2} to the same final-state, the same amplitudes which are necessary to produce a nonzero proton anomalous magnetic moment. The calculation requires the overlap of target light-front wavefunctions with different orbital angular momentum: ?Lz=1; thus the SSA in the Drell-Yan reaction provides a direct measure of orbital angular momentum in the QCD bound state. The single-spin asymmetry predicted for the Drell-Yan process ?p??? +? -X is similar to the single-spin asymmetries in deep inelastic semi-inclusive leptoproduction ? p???' ?X which arises from the final-state rescattering of the outgoing quark. The Bjorken-scaling single-spin asymmetries predicted for the Drell-Yan and leptoproduction processes highlight the importance of initial- and final-state interactions for QCD observables.

Brodsky, Stanley J.; Hwang, Dae Sung; Schmidt, Ivan

2002-10-01

229

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

NASA Astrophysics Data System (ADS)

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

Arenz, Christian; Gualdi, Giulia; Burgarth, Daniel

2014-06-01

230

Control of the spin geometric phase in semiconductor quantum rings  

PubMed Central

Since the formulation of the geometric phase by Berry, its relevance has been demonstrated in a large variety of physical systems. However, a geometric phase of the most fundamental spin-1/2 system, the electron spin, has not been observed directly and controlled independently from dynamical phases. Here we report experimental evidence on the manipulation of an electron spin through a purely geometric effect in an InGaAs-based quantum ring with Rashba spin-orbit coupling. By applying an in-plane magnetic field, a phase shift of the Aharonov–Casher interference pattern towards the small spin-orbit-coupling regions is observed. A perturbation theory for a one-dimensional Rashba ring under small in-plane fields reveals that the phase shift originates exclusively from the modulation of a pure geometric-phase component of the electron spin beyond the adiabatic limit, independently from dynamical phases. The phase shift is well reproduced by implementing two independent approaches, that is, perturbation theory and non-perturbative transport simulations. PMID:24067870

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

2013-01-01

231

Controlling chemical reactions of a single particle  

E-print Network

The control of chemical reactions is a recurring theme in physics and chemistry. Traditionally, chemical reactions have been investigated by tuning thermodynamic parameters, such as temperature or pressure. More recently, physical methods such as laser or magnetic field control have emerged to provide completely new experimental possibilities, in particular in the realm of cold collisions. The control of reaction pathways is also a critical component to implement molecular quantum information processing. For these undertakings, single particles provide a clean and well-controlled experimental system. Here, we report on the experimental tuning of the exchange reaction rates of a single trapped ion with ultracold neutral atoms by exerting control over both their quantum states. We observe the influence of the hyperfine interaction on chemical reaction rates and branching ratios, and monitor the kinematics of the reaction products. These investigations advance chemistry with single trapped particles towards achieving quantum-limited control of chemical reactions and indicate limits for buffer gas cooling of single ion clocks.

Lothar Ratschbacher; Christoph Zipkes; Carlo Sias; Michael Köhl

2012-09-26

232

Optical control of one and two hole spins in interacting quantum dots  

Microsoft Academic Search

A single hole spin in a semiconductor quantum dot has emerged as a quantum bit that is potentially superior to an electron spin. A key feature of holes is that they have a greatly reduced hyperfine interaction with nuclear spins, which is one of the biggest difficulties in working with an electron spin. It is now essential to show that

Alex Greilich; Samuel G. Carter; Danny Kim; Allan S. Bracker; Daniel Gammon

2011-01-01

233

Generator for single bubbles of controllable size  

NASA Astrophysics Data System (ADS)

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

Ohl, C. D.

2001-01-01

234

A brushless dc spin motor for momentum exchange altitude control  

NASA Technical Reports Server (NTRS)

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

Stern, D.; Rosenlieb, J. W.

1972-01-01

235

A light-induced spin crossover actuated single-chain magnet  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

236

Measurement of single transverse spin asymmetry AN in forward neutron production ?s=200GeV  

NASA Astrophysics Data System (ADS)

Relativistic Heavy Ion Collider (RHIC) completed its third run in May 2003. The run included a 5 week period in which it collided polarized proton at ?s=200GeV for the first time. Single transverse spin left-right asymmetries in neutron production were observed in the large rapidity region by the PHENIX collaboration using the Zero Degree Calorimeters (ZDC) and (embedded) segmented Shower Max Detectors (SMD). The results confirm the discovery of the left-right analyzing power in the p^arrowp arrow Nx process at RHIC [1] made last year. This year the asymmetries were used, first, for commissioning of the PHENIX spin rotators and then, during the physics run (measurement of double spin asymmetries A_LL) to monitor the proton spin direction. Longitudinal double spin asymmetry (A_LL) resulting from these data are expected to give the first glimpse of the role played by the gluons in determining the nucleon's spin. This talk will cover the status of the asymmetry analysis and comments on its origin, the use of these asymmetries in the commissioning of the spin rotators, and monitoring the spin direction of the proton during the physics data taking period. [1] Y. FUkao et al., Proceedings of SPIN 2002, to be published.

Deshpande, Abhay

2003-10-01

237

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

Microsoft Academic Search

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

238

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

Microsoft Academic Search

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

239

Spin splitting anisotropy in single diluted magnetic nanowire heterostructures.  

PubMed

We study the impact of the nanowire shape anisotropy on the spin splitting of excitonic photoluminescence. The experiments are performed on individual ZnMnTe/ZnMgTe core/shell nanowires as well as on ZnTe/ZnMgTe core/shell nanowires containing optically active magnetic CdMnTe insertions. When the magnetic field is oriented parallel to the nanowire axis, the spin splitting is several times larger than for the perpendicular field. We interpret this pronounced anisotropy as an effect of mixing of valence band states arising from the strain present in the core/shell geometry. This interpretation is further supported by theoretical calculations which allow to reproduce experimental results. PMID:25710186

Szymura, Ma?gorzata; Wojnar, Piotr; K?opotowski, ?ukasz; Suffczy?ski, Jan; Goryca, Mateusz; Smole?ski, Tomasz; Kossacki, Piotr; Zaleszczyk, Wojciech; Wojciechowski, Tomasz; Karczewski, Grzegorz; Wojtowicz, Tomasz; Kossut, Jacek

2015-03-11

240

Single spin asymmetries for identified hadrons at COMPASS  

NASA Astrophysics Data System (ADS)

COMPASS is a fixed target experiment at CERN SPS, dedicated to the study of the nucleon spin structure and hadron spectroscopy. The transverse spin structure of the nucleon is investigated by measuring semi-inclusive deep inelastic scattering (SIDIS) of a 160 GeV/c longitudinally polarized muon beam off transversely polarised targets. Particle Identification (PID) is performed with a Ring Imaging CHerenkov detector (RICH) that has been upgraded in 2005. COMPASS took data using transversely polarised 6LiD target from 2002 to 2004 and with a transversely polarised NH3 target in 2007. In this talk the Collins and Sivers asymmetries on polarised proton for charged pions and kaons will be shown for the first time and compared with the same results on polarised deuteron for COMPASS.

Pesaro, Giulia; Compass Collaboration

2011-05-01

241

Imaging single spin probes embedded in a conductive diamagnetic layer.  

SciTech Connect

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

Messina, P.; Fradin, F. (Materials Science Division)

2009-01-01

242

Thermal control of the spin pumping damping in ferromagnetic/normal metal interfaces  

NASA Astrophysics Data System (ADS)

A model is presented for the control of the magnetic relaxation in a ferromagnetic insulator (FMI) in contact with a normal metal (NM) under a thermal gradient applied across the thickness of the bilayer. We show that the thermal gradient modifies the spin pumping damping created by the contact of the NM with the FMI. This results from the bulk magnon spin current generated through the longitudinal spin Seebeck effect that superimposes to the spin pumping current at the FMI/NM interface, changing the FMI magnetic damping. The results of the model explain the experimental data on the control of the magnetic relaxation by thermal gradients measured by the linewidth of the ferromagnetic resonance absorption and by the attenuation of spin-wave packets propagating along a film of single-crystal yttrium iron garnet covered by a very thin platinum layer. Depending on the sign of the gradient, the relaxation rate can be increased or decreased, leading in the latter case to an apparent amplification.

Rezende, S. M.; Rodríguez-Suárez, R. L.; Azevedo, A.

2014-03-01

243

Voltage assisted control of spin-transfer nano-oscillators  

NASA Astrophysics Data System (ADS)

The spin-transfer nano-oscillator (STNO) has recently acquired a huge amount of research interest, due to its promising easy tunability along with the miniature size. The output frequency control of an STNO through magnetic field and current has been examined almost to its full extent; however, there are issues that still need to be addressed. Here, we propose a novel way of voltage control of the output frequency of an STNO, and alongside reducing its power requirement.

Ghosh, Bahniman; Solanki, Gaurav

2015-03-01

244

All-optical initialization, readout, and coherent preparation of single silicon-vacancy spins in diamond.  

PubMed

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 29Si 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

245

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

PubMed Central

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

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

2013-01-01

246

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

PubMed

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

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

2012-03-30

247

Coherent Sensing of a Mechanical Resonator with a Single-Spin Qubit  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

248

Probing the motion of a mechanical resonator via coherent coupling to a single spin qubit  

NASA Astrophysics Data System (ADS)

Mechanical systems can be influenced by a wide variety of extremely small forces, ranging from gravitational to optical, electrical, and magnetic. When mechanical resonators are scaled down to nanometer-scale dimensions, these forces can be harnessed to enable coupling to individual quantum systems. In this talk we will present results showing that the coherent evolution of a single electronic spin associated with a Nitrogen Vacancy (NV) center in diamond can be coupled to the motion of a magnetized mechanical resonator. Specifically we use coherent manipulation of the spin to sense the driven and Brownian motion of the resonator under ambient conditions at a picometer length scale. We will discuss potential applications of this technique including the decetion of the zero-point fluctuations of a mechanical resonator, the realization of strong spin-phonon coupling at a single quantum level, and the implementation of quantum spin transducers.

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

2012-02-01

249

Single-spin asymmetries in inclusive DIS and in hadronic collisions  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

250

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

NASA Astrophysics Data System (ADS)

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

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

251

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

252

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

253

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

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

254

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

PubMed

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

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

2010-07-28

255

Time optimal control in spin systems  

Microsoft Academic Search

In this paper, we study the design of pulse sequences for nuclear magnetic resonance spectroscopy as a problem of time optimal control of the unitary propagator. Radio-frequency pulses are used in coherent spectroscopy to implement a unitary transfer between states. Pulse sequences that accomplish a desired transfer should be as short as possible in order to minimize the effects of

Navin Khaneja; Roger Brockett; Steffen J. Glaser

2001-01-01

256

Reversible Polarization Control of Single Photon Emission  

Microsoft Academic Search

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

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

2008-01-01

257

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

SciTech Connect

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

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

2013-11-04

258

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

259

Ultralong spin memory of optically excited single magnetic quantum dots  

NASA Astrophysics Data System (ADS)

We study the magnetization dynamics in CdMnTe quantum dots using subwavelength optical microscopy imaging at B =0 T. For continuous laser illumination each dot exhibits strong and unique circular polarization despite completely unpolarized ensemble emission. This implies that after an exciton recombines, the spontaneous ferromagnetic alignment of magnetic impurities persists for over 100 ?s, which is a million times longer than in CdMnTe quantum wells. The spin memory effect points toward a qualitatively different picture of magnetization dynamics in the zero-dimensional limit.

Gurung, Tak; Mackowski, Sebastian; Karczewski, Grzegorz; Jackson, Howard E.; Smith, Leigh M.

2008-10-01

260

Quantum control and measurement of spins in laser cooled gases  

NASA Astrophysics Data System (ADS)

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

Deutsch, Ivan

2012-10-01

261

Single Scale Cluster Expansions with Applications to Many Boson and Unbounded Spin Systems  

E-print Network

We develop a cluster expansion to show exponential decay of correlations for quite general single scale spin systems, as they arise in lattice quantum field theory and discretized functional integral representations for observables of quantum statistical mechanics. We apply our results to: the small field approximation to the coherent state correlation functions of the grand canonical Bose gas at negative chemical potential, constructed by Balaban, Feldman, Kn\\"orrer and Trubowitz (2010); and to N component unbounded spin systems with repulsive two body interaction and massive, possibly complex, covariance. Our cluster expansion is derived by a single application of the BKAR interpolation formula.

Martin Lohmann

2014-11-04

262

Controllable entanglement transfer via two parallel spin chains  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

263

Transport through artificial single-molecule magnets: Spin-pair state sequential tunneling and Kondo effects  

NASA Astrophysics Data System (ADS)

The transport properties of an artificial single-molecule magnet based on a CdTe quantum dot doped with a single Mn+2 ion (S=5/2) are investigated by the non-equilibrium Green function method. We consider a minimal model where the Mn—hole exchange coupling is strongly anisotropic so that spin-flip is suppressed and the impurity spin S and a hole spin s entering the quantum dot are coupled into spin pair states with (2S+1) sublevels. In the sequential tunneling regime, the differential conductance exhibits (2S+1) possible peaks, corresponding to resonance tunneling via (2S+1) sublevels. At low temperature, Kondo physics dominates transport and (2S+1) Kondo peaks occur in the local density of states and conductance. These peaks originate from the spin-singlet state formed by the holes in the leads and on the dot via higher-order processes and are related to the parallel and antiparallel spin pair states.

Niu, Peng-Bin; Wang, Qiang; Nie, Yi-Hang

2013-02-01

264

Electrostatic spin control in multi-barrier nanowires  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

265

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

SciTech Connect

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

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

2013-12-04

266

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

SciTech Connect

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

267

Linear spin wave theory for single-Q incommensurate magnetic structures.  

PubMed

Linear spin wave theory provides the leading term in the calculation of the excitation spectra of long-range ordered magnetic systems as a function of [Formula: see text]. This term is acquired using the Holstein-Primakoff approximation of the spin operator and valid for small ?S fluctuations of the ordered moment. We propose an algorithm that allows magnetic ground states with general moment directions and single-Q incommensurate ordering wave vector using a local coordinate transformation for every spin and a rotating coordinate transformation for the incommensurability. Finally we show, how our model can determine the spin wave spectrum of the magnetic C-site langasites with incommensurate order. PMID:25817594

Toth, S; Lake, B

2015-04-29

268

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

SciTech Connect

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

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

1988-05-13

269

Controllable spin-charge transport in strained graphene nanoribbon devices  

SciTech Connect

We theoretically investigate the spin-charge transport in two-terminal device of graphene nanoribbons in the presence of a uniform uniaxial strain, spin-orbit coupling, exchange field, and smooth staggered potential. We show that the direction of applied strain can efficiently tune strain-strength induced oscillation of band-gap of armchair graphene nanoribbon (AGNR). It is also found that electronic conductance in both AGNR and zigzag graphene nanoribbon (ZGNR) oscillates with Rashba spin-orbit coupling akin to the Datta-Das field effect transistor. Two distinct strain response regimes of electronic conductance as function of spin-orbit couplings magnitude are found. In the regime of small strain, conductance of ZGNR presents stronger strain dependence along the longitudinal direction of strain. Whereas for high values of strain shows larger effect for the transversal direction. Furthermore, the local density of states shows that depending on the smoothness of the staggered potential, the edge states of AGNR can either emerge or be suppressed. These emerging states can be determined experimentally by either spatially scanning tunneling microscope or by scanning tunneling spectroscopy. Our findings open up new paradigms of manipulation and control of strained graphene based nanostructure for application on novel topological quantum devices.

Diniz, Ginetom S., E-mail: ginetom@gmail.com; Guassi, Marcos R. [Institute of Physics, University of Brasília, 70919-970, Brasília-DF (Brazil); Qu, Fanyao [Institute of Physics, University of Brasília, 70919-970, Brasília-DF (Brazil); Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States)

2014-09-21

270

Controllable spin-charge transport in strained graphene nanoribbon devices  

NASA Astrophysics Data System (ADS)

We theoretically investigate the spin-charge transport in two-terminal device of graphene nanoribbons in the presence of a uniform uniaxial strain, spin-orbit coupling, exchange field, and smooth staggered potential. We show that the direction of applied strain can efficiently tune strain-strength induced oscillation of band-gap of armchair graphene nanoribbon (AGNR). It is also found that electronic conductance in both AGNR and zigzag graphene nanoribbon (ZGNR) oscillates with Rashba spin-orbit coupling akin to the Datta-Das field effect transistor. Two distinct strain response regimes of electronic conductance as function of spin-orbit couplings magnitude are found. In the regime of small strain, conductance of ZGNR presents stronger strain dependence along the longitudinal direction of strain. Whereas for high values of strain shows larger effect for the transversal direction. Furthermore, the local density of states shows that depending on the smoothness of the staggered potential, the edge states of AGNR can either emerge or be suppressed. These emerging states can be determined experimentally by either spatially scanning tunneling microscope or by scanning tunneling spectroscopy. Our findings open up new paradigms of manipulation and control of strained graphene based nanostructure for application on novel topological quantum devices.

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

2014-09-01

271

Continuous spinning of a single-walled carbon nanotube-nylon composite fiber.  

PubMed

We report a chemical processing technology that allows the continuous spinning of single-walled carbon nanotubes (SWNTs)-nylon 6 (PA6) fibers by the in-situ polymerization of caprolactam in the presence of SWNTs, which simultaneously optimizes the morphology of the composite. We show that caprolactam is an excellent solvent for carboxylic-acid-functionalized SWNTs (SWNT-COOH) and that this allows the efficient dispersal of the SWNTs and subsequent grafting of PA6 chains to the SWNTs through condensation reactions between the carboxylic-acid group on SWNT-COOH and the terminal amine group of PA6. The existence of a graft copolymer between the PA6 chains and the SWNTs is demonstrated by IR, TGA, and AFM studies, and we show that the solubility of the polymerized material in formic acid is controlled by the degree of graft copolymerization. The amount of grafted PA6 chains that are attached to the SWNTs can be adjusted by controlling the concentration of the initiator (6-aminocaproic acid). The process leads to a uniform dispersion of the SWNTs, and the presence of the graft copolymer increases the polymer/SWNT compatibility while strengthening the interfacial interaction between the nanotube and matrix. The Young's modulus, tensile strength, and thermal stability of the SWNT-reinforced composite fibers produced by this process are significantly improved. PMID:15771520

Gao, Junbo; Itkis, Mikhail E; Yu, Aiping; Bekyarova, Elena; Zhao, Bin; Haddon, Robert C

2005-03-23

272

High spin single particle states in 152,153Er  

NASA Astrophysics Data System (ADS)

A spectroscopic investigation of yrast and near-yrast states in 152Er and 153Er is presented. We report measurements of prompt and delayed excitation functions, ?-? coincidences, isomeric lifetimes, and ?-ray angular distribution, obtained chiefly from the reactions 144Sm(12C,xn)152,153Er using carbon beams of laboratory energy 65-95 MeV. The levels observed extend to a spin of J>=432 and include two long-lived isomers in 153Er. The nuclear structure is discussed in terms of the shell model and compared with the systematic behavior of levels in N=84 and N=85 isotones. NUCLEAR REACTIONS 144Sm(12C,xn) E=65-95 MeV; 144Sm(11B,xn) E=40-70 MeV; 124Te(32S,xn) E=125-155 MeV. Measured I?(E,t), I?(?), ?-?(t). Deduced level sequences, T12, J?. Continuous and pulsed beams, enriched targets, Ge(Li) detectors, NaI(Tl) multiplicity filter.

Horn, D.; Young, G. R.; Lister, C. J.; Baktash, C.

1981-03-01

273

Mesoscopic effects in a single-mode Datta-Das spin field-effect transistor  

NASA Astrophysics Data System (ADS)

We study a single-mode Datta-Das spin field-effect transistor (SFET) in the presence (absence) of impurity scattering and external magnetic fields, and find interesting mesoscopic effects such as peak splitting, phase locking, and period halving. Experimental observation of these effects appears to be feasible in a single-mode SFET made of materials such as InGaAs/InAlAs .

Lee, Hyun-Woo; Çal??kan, S.; Park, Hyowon

2005-10-01

274

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

275

Dynamics and Control of a Quasi-1D Spin System  

E-print Network

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

Paola Cappellaro; Chandrasekhar Ramanathan; David G. Cory

2007-06-04

276

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

277

RF instrumentation and system design for coherent control of anisotropic hyperfine-coupled electron/nuclear spin qubits  

E-print Network

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

278

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

E-print Network

Coherent Control of a Nitrogen-Vacancy Center Spin Ensemble with a Diamond Mechanical Resonator E Cornell University, Ithaca, NY 14853 Abstract Coherent control of the nitrogen-vacancy (NV) center of how spin systems interact with their environment. The spin triplet ground state of the nitrogen

Afshari, Ehsan

279

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

E-print Network

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

Yang, Jamie Chiaming

2008-01-01

280

Coupling a single spin in diamond to the quantum motion of a mechanical cantilever  

NASA Astrophysics Data System (ADS)

We present theoretical considerations for a magnetized mechanical cantilever coupled to a single electronic spin associated with a nitrogen-vacancy (NV) defect center in diamond. This coupled system has recently been implemented in an experiment where the NV spin was used to detect the thermal motion of a magnetic force microscope cantilever at room temperature, reading out the spin state optically using the spin-selective fluorescence of the NV. The possibility to extend this system to the quantum regime opens the door to applications such as readout and transfer of quantum information, as well as interesting theoretical questions. For example, it should be possible to reach the regime of strong coupling between the spin and the motion of the cantilever, in analogy to cavity quantum electrodynamics. We discuss the prospects for reaching the strong coupling regime and the conditions for measuring the onset of quantum effects, such as measuring the zero point motion of the cantilever using the spin as a detector.

Bennett, Steven; Kolkowitz, Shimon; Unterreithmeier, Quirin; Rabl, Peter; Bleszynski-Jayich, Ania; Harris, Jack; Lukin, Mikhail

2012-02-01

281

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

SciTech Connect

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

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

2011-12-15

282

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

NASA Astrophysics Data System (ADS)

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

2011-12-01

283

Sub-optical resolution of single spins using magnetic resonance imaging at room temperature in diamond  

E-print Network

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

284

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

E-print Network

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

Emmanuel Floratos; Georgios Linardopoulos

2014-09-12

285

Controlling quantum transport through a single molecule.  

PubMed

We investigate multiterminal quantum transport through single monocyclic aromatic annulene molecules, and their derivatives, using the nonequilibrium Green function approach within the self-consistent Hartree-Fock approximation. We propose a new device concept, the quantum interference effect transistor, that exploits perfect destructive interference stemming from molecular symmetry and controls current flow by introducing decoherence and/or elastic scattering that break the symmetry. This approach overcomes the fundamental problems of power dissipation and environmental sensitivity that beset nanoscale device proposals. PMID:17090067

Cardamone, David M; Stafford, Charles A; Mazumdar, Sumit

2006-11-01

286

Controlled synthesis of single-crystalline graphene  

SciTech Connect

This paper reports the controlled synthesis of single-crystalline graphene on the back side of copper foil using CH{sub 4} as the precursor. The influence of growth time and the pressure ratio of CH{sub 4}/H{sub 2} on the structure of graphene are examined. An optimized polymer-assisted method is used to transfer the synthesized graphene onto a SiO{sub 2}/Si substrate. Scanning electron microscopy and Raman spectroscopy are used to characterize the graphene.

Xueshen, Wang, E-mail: wangxs@nim.ac.cn; Jinjin, Li, E-mail: jinjinli@nim.ac.cn; Qing, Zhong; Yuan, Zhong; Mengke, Zhao; Yonggang, Liu [National Institute of Metrology, Beijing, China, 100013 (China)] [National Institute of Metrology, Beijing, China, 100013 (China)

2014-03-15

287

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

Microsoft Academic Search

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

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

2007-01-01

288

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

SciTech Connect

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

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

2010-01-29

289

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

PubMed Central

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

Ban, Yue; Chen, Xi

2014-01-01

290

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

PubMed

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

Ban, Yue; Chen, Xi

2014-01-01

291

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

NASA Astrophysics Data System (ADS)

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

Ban, Yue; Chen, Xi

2014-09-01

292

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

NASA Technical Reports Server (NTRS)

Flight tests were performed to investigate the stall, spin, and recovery characteristics of a four-place, low-wing, single-engine, T-tail, general aviation research airplane at an aft center-of-gravity position. Most stalls resulted in roll-offs. Spins were oscillatory in roll and pitch at 43 deg angle of attack; the magnitude of the oscillations was determined by aileron position. Power, flap deflection, and landing gear position did not affect the angle of attack to the spin. Antispin rudder followed by forward wheel with ailerons neutral produced the fastest and most consistent recoveries but the initial application of recovery controls did not always stop a spin.

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

1985-01-01

293

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

E-print Network

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

Chunyang Tang; Xin Hu; Xinyu Pan

2010-09-09

294

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

E-print Network

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 (MDI). 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 -ac systems with various temperatures and sweeping field 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 3K and the thermal-assisted tunnelings play important roles at intermediate temperature. Our magnetization curves are satisfactory compared to experimental results, considering possible...

Liu, Gui-Bin

2010-01-01

295

Measurement of z-direction component of electron spins field-emitted from a single-crystal magnetite whisker.  

PubMed

A 90° sector type spin rotator was developed for measurement of the z-direction component of a spin polarization, which is parallel to the emitter axis. The rotator enables us to measure all components of electron spins field-emitted from a single crystalline magnetite. In-plane component of spin polarization dominated of field-emitted electrons from single crystalline magnetite whisker, thus it is suggested that the magnetization of the magnetite whisker results from the anisotropy of crystalline structure rather than its shape. PMID:21664540

Nagai, S; Sakakibara, H; Hata, K; Okada, M; Mimura, H

2011-05-01

296

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

SciTech Connect

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

297

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

298

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

PubMed

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

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

2012-08-29

299

Terahertz probes of magnetic field induced spin reorientation in YFeO3 single crystal  

NASA Astrophysics Data System (ADS)

Using the terahertz time-domain spectroscopy, we demonstrate the spin reorientation of a canted antiferromagnetic YFeO3 single crystal, by evaluating the temperature and magnetic field dependence of resonant frequency and amplitude for the quasi-ferromagnetic (FM) and quasi-antiferromagnetic modes (AFM), a deeper insight into the dynamics of spin reorientation in rare-earth orthoferrites is established. Due to the absence of 4f-electrons in Y ion, the spin reorientation of Fe sublattices can only be induced by the applied magnetic field, rather than temperature. In agreement with the theoretical predication, the frequency of FM mode decreases with magnetic field. In addition, an obvious step of spin reorientation phase transition occurs with a relatively large applied magnetic field of 4 T. By comparison with the family members of RFeO3 (R = Y3+ or rare-earth ions), our results suggest that the chosen of R would tailor the dynamical rotation properties of Fe ions, leading to the designable spin switching in the orthoferrite antiferromagnetic systems.

Lin, Xian; Jiang, Junjie; Jin, Zuanming; Wang, Dongyang; Tian, Zhen; Han, Jiaguang; Cheng, Zhenxiang; Ma, Guohong

2015-03-01

300

Theory of electrically controlled resonant tunneling spin devices  

NASA Technical Reports Server (NTRS)

We report device concepts that exploit spin-orbit coupling for creating spin polarized current sources using nonmagnetic semiconductor resonant tunneling heterostructures, without external magnetic fields. The resonant interband tunneling psin filter exploits large valence band spin-orbit interaction to provide strong spin selectivity.

Ting, David Z. -Y.; Cartoixa, Xavier

2004-01-01

301

Quantum electronics. Probing Johnson noise and ballistic transport in normal metals with a single-spin qubit.  

PubMed

Thermally induced electrical currents, known as Johnson noise, cause fluctuating electric and magnetic fields in proximity to a conductor. These fluctuations are intrinsically related to the conductivity of the metal. We use single-spin qubits associated with nitrogen-vacancy centers in diamond to probe Johnson noise in the vicinity of conductive silver films. Measurements of polycrystalline silver films over a range of distances (20 to 200 nanometers) and temperatures (10 to 300 kelvin) are consistent with the classically expected behavior of the magnetic fluctuations. However, we find that Johnson noise is markedly suppressed next to single-crystal films, indicative of a substantial deviation from Ohm's law at length scales below the electron mean free path. Our results are consistent with a generalized model that accounts for the ballistic motion of electrons in the metal, indicating that under the appropriate conditions, nearby electrodes may be used for controlling nanoscale optoelectronic, atomic, and solid-state quantum systems. PMID:25636797

Kolkowitz, S; Safira, A; High, A A; Devlin, R C; Choi, S; Unterreithmeier, Q P; Patterson, D; Zibrov, A S; Manucharyan, V E; Park, H; Lukin, M D

2015-03-01

302

Orientation-controlled single-molecule junctions.  

PubMed

The conductivity of a single aromatic ring, perpendicular to its plane, is determined using a new strategy under ambient conditions and at room temperature by a combination of molecular assembly, scanning tunneling microscopy (STM) imaging, and STM break junction (STM-BJ) techniques. The construction of such molecular junctions exploits the formation of highly ordered structures of flat-oriented mesitylene molecules on Au(111) to enable direct tip/? contacts, a result that is not possible by conventional methods. The measured conductance of Au/?/Au junction is about 0.1?G(o)?, two orders of magnitude higher than the conductance of phenyl rings connected to the electrodes by standard anchoring groups. Our experiments suggest that long-range ordered structures, which hold the aromatic ring in place and parallel to the surface, are essential to increase probability of the formation of orientation-controlled molecular junctions. PMID:25044431

Afsari, Sepideh; Li, Zhihai; Borguet, Eric

2014-09-01

303

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

E-print Network

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

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

2014-10-02

304

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

305

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

Microsoft Academic Search

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

Atsushi Goto; Tadashi Shimizu; Kenjiro Hashi; Hideaki Kitazawa

2002-01-01

306

Single-Spin Transverse Asymmetry in Neutral Pion Production at PHENIX  

NASA Astrophysics Data System (ADS)

The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) began operation as the first polarized proton collider in 2001. From data collected in the 2001-2002 run, the PHENIX experiment has measured the single-spin transverse asymmetry (A_N) for neutral pion production at x_F ˜0 over a transverse momentum range of 1.0 to 5.0 GeV/c from polarized proton-proton interactions at a center of mass energy (?s) of 200 GeV. Interest in these measurements arises from the observation of large ( ˜10-30%) single-spin transverse asymmetries in pp_arrowarrow? X at forward angles by the E704 collaboration at Fermilab (?s = 19.4GeV) and the STAR collaboration at RHIC (?(s) = 200GeV), as well as single-spin, azimuthal asymmetries in semi-inclusive deep-inelastic scattering by the HERMES collaboration at DESY. Such large asymmetries were initially surprising because, at leading-order, pQCD predicts only small effects. Recently it has been argued that these large asymmetries may be produced by initial-state effects (e.g. the Sivers effect), final-state effects (e.g. transversity with the Collins effect), higher-twist contributions, or a combination of the three. In this talk, we will report on the results ofthis measurement.

Aidala, Christine

2004-05-01

307

Electron-nuclear spin control in charged semiconductor quantum dots by electrical currents through micro-coils  

NASA Astrophysics Data System (ADS)

We have fabricated micrometer-sized single-turn coils on top of charged CdSe/ZnSe quantum dot heterostructures by lithographical techniques. Current injection creates magnetic fields in the some 10 mT range, strong enough to modulate the hyperfine interaction. The very low coil inductance allows for generation of fast field transients. We demonstrate local control of the resident electron spin as well as read-out of the nuclear spin state on the 10 ns time scale by electrical current pulses.

Kim, Jungtaek; Puls, J.; Chen, Y. S.; Bacher, G.; Henneberger, F.

2010-04-01

308

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

NASA Astrophysics Data System (ADS)

We present a technique for addressing single nitrogen-vacancy (NV) center spins in diamond over macroscopic distances using a tunable dielectric microwave cavity. We demonstrate optically detected magnetic resonance (ODMR) for a single negatively charged NV center (NV-) in a nanodiamond (ND) located directly under the macroscopic microwave cavity. By moving the cavity relative to the ND, we record the ODMR signal as a function of position, mapping out the distribution of the cavity magnetic field along one axis. In addition, we argue that our system could be used to determine the orientation of the NV- major axis in a straightforward manner.

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

2014-09-01

309

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

SciTech Connect

We study the single transverse spin asymmetries in the single inclusive particle production within the framework of the generalized parton model (GPM). By carefully analyzing the initial- and final-state interactions, we include the process-dependence of the Sivers functions into the GPM formalism. The modified GPM formalism has a close connection with the collinear twist-3 approach. Within the new formalism, we make predictions for inclusive {pi}{sup 0} and direct photon productions at RHIC energies. We find the predictions are opposite to those in the conventional GPM approach.

Leonard Gamberg, Zhong-Bo Kang

2011-01-01

310

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

SciTech Connect

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

311

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

NASA Astrophysics Data System (ADS)

Iron(II) phthalocyanine (FePc) molecule causes novel Kondo effects derived from the unique electronic structure of multi-spins and multi-orbitals when attached to Au(111). Two unpaired electrons in the dz2 and the degenerate d? orbitals are screened stepwise, resulting in spin and spin+orbital Kondo effects, respectively. We investigated the impact on the Kondo effects of the coordination of CO and NO molecules to the Fe2+ ion as chemical stimuli by using scanning tunneling microscopy (STM) and density functional theory calculations. The impacts of the two diatomic molecules are different from each other as a result of the different electronic configurations. The coordination of CO converts the spin state from triplet to singlet, and then the Kondo effects completely disappear. In contrast, an unpaired electron survives in the molecular orbital composed of Fe dz2 and NO 5? and 2?* orbitals for the coordination of NO, causing a sharp Kondo resonance. The isotropic magnetic response of the peak indicates the origin is the spin Kondo effect. The diatomic molecules attached to the Fe2+ ion were easily detached by applying a pulsed voltage at the STM junction. These results demonstrate that the single molecule chemistry enables us to switch and control the spin and the many-body quantum states reversibly.

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

2014-08-01

312

State Controller's Office Single Audit Status Report Legend  

E-print Network

State Controller's Office Single Audit Status Report Legend Missing Audit Report Packages Letter 0 Financial Statement Report 0 Single Audit Report 0 Missing Documents Summary Status Report State and Documents The State Controller's Office (SCO) either has not received a Single Audit Reporting Package

313

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

314

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

SciTech Connect

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

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

2013-12-16

315

Using heat to control the sample spinning speed in MAS NMR  

NASA Astrophysics Data System (ADS)

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

Mihaliuk, Eugene; Gullion, Terry

2011-10-01

316

Spin  

Microsoft Academic Search

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

317

Photonic spin control for solar wind electric sail  

NASA Astrophysics Data System (ADS)

The electric solar wind sail (E-sail) is a novel, efficient propellantless propulsion concept which utilises the natural solar wind for spacecraft propulsion with the help of long centrifugally stretched charged tethers. The E-sail requires auxiliary propulsion applied to the tips of the main tethers for creating the initial angular momentum and possibly for modifying the spinrate later during flight to counteract the orbital Coriolis effect and possibly for mission specific reasons. We introduce the possibility of implementing the required auxiliary propulsion by small photonic blades (small radiation pressure solar sails). The blades would be stretched centrifugally. We look into two concepts, one with and one without auxiliary tethers. The use of small photonic sails has the benefit of providing sufficient spin modification capability for any E-sail mission while keeping the technology fully propellantless. We conclude that small photonic sails appear to be a feasible and attractive solution to E-sail spinrate control.

Janhunen, Pekka

2013-02-01

318

Spin-polarized density-matrix functional theory of the single-impurity Anderson model  

NASA Astrophysics Data System (ADS)

Lattice density functional theory (LDFT) is used to investigate spin excitations in the single-impurity Anderson model. In this method, the single-particle density matrix ?ij? with respect to the lattice sites replaces the wave function as the basic variable of the many-body problem. A recently developed two-level approximation (TLA) to the interaction-energy functional W[?] is extended to systems having spin-polarized density distributions and bond orders. This allows us to investigate the effect of external magnetic fields and, in particular, the important singlet-triplet gap ?E, which determines the Kondo temperature. Applications to finite Anderson rings and square lattices show that the gap ?E as well as other ground-state and excited-state properties are very accurately reproduced. One concludes that the spin-polarized TLA is reliable in all interaction regimes, from weak to strong correlations, for different hybridization strengths and for all considered impurity valence states. In this way the efficiency of LDFT to account for challenging electron-correlation effects is demonstrated.

Töws, W.; Pastor, G. M.

2012-12-01

319

Controlling spin-orbit interaction in a ferromagnetic Fe/Au double layer  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

320

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

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

321

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

322

Spin Filtering and Entanglement Swapping through Coherent Evolution of a Single Quantum Dot  

E-print Network

We exploit the non-dissipative 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 AKLT 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 choice of dot-size and initialization errors, as well as decoherence introduced by the hyperfine interaction.

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

2010-08-18

323

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

324

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

325

Spin-lattice relaxation times of single donors and donor clusters in silicon.  

PubMed

An atomistic method of calculating the spin-lattice relaxation times (T?) 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 T? 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 B?, in excellent quantitative agreement with experimental measurements. The results also show that by engineering electronic wave functions in nanostructures, T? times can be varied by orders of magnitude. PMID:25541787

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

2014-12-12

326

Transverse single spin and azimuthal asymmetries in hadronic collisions at PHENIX  

NASA Astrophysics Data System (ADS)

Inclusive transverse single spin asymmetries from high energetic polarized proton proton collisions provide insight into the spin-momentum correlations in QCD. Originally expected to be small in collinear perturbative QCD, results from PHENIX and other experiments show significant asymmetries in the forward momentum direction of the polarized proton over a wide range of center-of-mass energies. Several mechanisms have been proposed that attempt to explain these asymmetries, which include initial and final state effects. In order to disentangle these effects, a variety of probes is needed in different kinematic regions. In the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC), we study polarized p+p collisions at center-of-mass energies up to 500 GeV. We will show transverse asymmetries at forward (3.1< |?| <3.8) and central rapidities (|?| <0.35) and discuss their possible implications for intitial and final state effects.

Kleinjan, David

2015-01-01

327

All-Optical Sensing of a Single-Molecule Electron Spin  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

328

Strongly Enhanced Spin Squeezing via Quantum Control Collin M. Trail,1,* Poul S. Jessen,2  

E-print Network

squeezing based on a double-pass Faraday interaction between an optical probe and an optically dense atomic the polarization of a probe pulse is correlated with the spin through Faraday rotation during a first pass sample. A quantum eraser is used to remove residual spin- probe entanglement, thereby realizing a single

Jessen, Poul S.

329

Robust state transfer with high fidelity in spin-1/2 chains by Lyapunov control  

NASA Astrophysics Data System (ADS)

Based on the Lyapunov control, we present a scheme to realize state transfer with high fidelity by only modulating the boundary spins in a quantum spin-1/2 chain. Recall that the conventional transmission protocols aim at nonstationary state (or information) transfer from the first spin to the end spin at a fixed time. The present scheme possesses the following advantages. First, the scheme does not require precise manipulations of the control time. Second, it is robust against uncertainties in the initial states and fluctuations in the control fields. Third, the controls are exerted only on the boundary sites of the chain. It works for variable spin-1/2 chains with different periodic structures and has good scalability. The feasibility to replace the control fields by square pules is explored, which simplifies the realization in experiments.

Shi, Z. C.; Zhao, X. L.; Yi, X. X.

2015-03-01

330

Flight investigation of the effects of an outboard wing-leading-edge modification on stall/spin characteristics of a low-wing, single-engine, T-tail light airplane  

NASA Technical Reports Server (NTRS)

Flight tests were performed to investigate the change in stall/spin characteristics due to the addition of an outboard wing-leading-edge modification to a four-place, low-wing, single-engine, T-tail, general aviation research airplane. Stalls and attempted spins were performed for various weights, center of gravity positions, power settings, flap deflections, and landing-gear positions. Both stall behavior and wind resistance were improved compared with the baseline airplane. The latter would readily spin for all combinations of power settings, flap deflections, and aileron inputs, but the modified airplane did not spin at idle power or with flaps extended. With maximum power and flaps retracted, the modified airplane did enter spins with abused loadings or for certain combinations of maneuver and control input. The modified airplane tended to spin at a higher angle of attack than the baseline airplane.

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

1987-01-01

331

Polytype control of spin qubits in silicon carbide  

PubMed Central

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

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

2013-01-01

332

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

PubMed

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

Zhang, Xing; Herbert, John M

2014-08-14

333

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

SciTech Connect

Single-transverse spin asymmetries (SSA) in strong interactions have a long history, starting from the 1970s and 1980s when surprisingly large single-transverse spin asymmetries were observed in p+p {yields} {pi}X and pp {yields} {Lambda} + X, where really none were expected. They have again attracted much interest in recent years from both experimental and theoretical sides. In particular, first measurements by the STAR, PHENIX, and BRAHMS collaborations at RHIC have now become available which again reveal large single transverse spin asymmetries for hadron production in polarized proton proton scattering. This extends the SSA observations from the fixed target energy range to the collider regime. Meanwhile, experimental studies in Deep Inelastic Scattering by the HERMES collaboration at DESY, SMC at CERN, and CLAS at JLab also show a remarkably large SSA in semi-inclusive hadron production, {gamma}*p {yields} {pi}X, when the proton is transversely polarized. On the theoretical side, there are several approaches to understanding SSA within Quantum Chromodynamics (QCD). For example, to explain the large SSAs for hadron production in hadron collisions, a mechanism that takes into account the contribution from quark-gluon-quark correlations (twist-3) in the nucleon was proposed. On the other hand, possible origins of SSA in DIS and hadronic scattering were also found in leading-twist transverse momentum dependent parton distributions. Current theoretical efforts aim at a better conceptual understanding of these two types of mechanisms, and of their connections. We were very happy at this timely date to bring together the theorists and experimentalists of this field to review and discuss the current theoretical status and the latest experimental results. The whole workshop contained 25 formal talks, both experiment (15) and theory (10), and a few informal talks and many fruitful discussions. The topics covered all the relevant SSA observables, including in Deep Inelastic Scattering, the Drell-Yan process, and in inclusive hadron production and dijet correlations at hadron colliders. There were not only discussions on possible interpretations of the existing SSA data, but also on the future observables for the ongoing experiments as well as for planned experiments (such as RHIC II and eRHIC). On the theory side, the talks ranged from overviews and descriptions of the fundamental aspects of SSAs, to presentations of detailed phenomenological studies. All of the talks attracted much interest and initiated active discussions. Directions for future measurements were pointed out, in particular for studies at RHIC. Also, significant theoretical advances were made that may tie together some of the currently proposed mechanisms for single-spin asymmetries. This was a very successful workshop. It stimulated many discussions and new collaborations.

YUAN, F.; VOGELSANG, W.

2005-06-01

334

Single-spin azimuthal asymmetry in exclusive electroproduction of ?+ mesons on transversely polarized protons  

NASA Astrophysics Data System (ADS)

Exclusive electroproduction of ? mesons was studied by scattering 27.6 GeV positrons or electrons off a transversely polarized hydrogen target. The single-spin azimuthal asymmetry with respect to target polarization was measured as a function of the Mandelstam variable t, the Bjorken scaling variable xB, and the virtuality Q of the exchanged photon. The extracted Fourier components of the asymmetry were found to be consistent with zero, except one that was found to be large and that involves interference of contributions from longitudinal and transverse virtual photons.

Airapetian, A.; Akopov, N.; Akopov, Z.; Aschenauer, E. C.; Augustyniak, W.; Avetissian, A.; Avetisyan, E.; Ball, B.; Belostotski, S.; Bianchi, N.; Blok, H. P.; Böttcher, H.; Bonomo, C.; Borissov, A.; 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.; Dreschler, J.; Düren, M.; Ehrenfried, M.; Elbakian, G.; Ellinghaus, F.; Fabbri, R.; Fantoni, A.; Felawka, L.; Frullani, S.; Gabbert, D.; Gapienko, V.; Garibaldi, F.; Gharibyan, V.; Giordano, F.; Gliske, S.; Hadjidakis, C.; Hartig, M.; Hasch, D.; Hill, G.; Hillenbrand, A.; Hoek, M.; Holler, Y.; Hristova, I.; Imazu, Y.; Ivanilov, A.; Jackson, H. E.; Jo, H. S.; Joosten, S.; Kaiser, R.; Keri, T.; Kinney, E.; Kisselev, A.; Kobayashi, N.; Korotkov, V.; Kravchenko, P.; Lagamba, L.; Lamb, R.; Lapikás, L.; Lehmann, I.; Lenisa, P.; Linden-Levy, L. A.; López Ruiz, A.; Lorenzon, W.; Lu, X.-G.; Lu, X.-R.; Ma, B.-Q.; Mahon, D.; Makins, N. C. R.; Manaenkov, S. I.; Manfré, L.; Mao, Y.; Marianski, B.; Martinez de La Ossa, B.; Marukyan, H.; Miller, C. A.; Miyachi, Y.; Movsisyan, A.; Muccifora, V.; Murray, M.; Mussgiller, A.; Nappi, E.; Naryshkin, Y.; Nass, A.; Nowak, W.-D.; Pappalardo, L. L.; Perez-Benito, R.; 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.; Schüler, K. P.; Seitz, B.; Shibata, T.-A.; Shutov, V.; Stancari, M.; Statera, M.; Steijger, J. J. M.; Stenzel, H.; Stewart, J.; Taroian, S.; Terkulov, A.; Trzcinski, A.; Tytgat, M.; Vandenbroucke, A.; van der Nat, P. B.; van Haarlem, Y.; van Hulse, C.; Varanda, M.; Veretennikov, D.; Vikhrov, V.; Vilardi, I.; Vogel, C.; Wang, S.; Yaschenko, S.; Ye, H.; Ye, Z.; Yen, S.; Yu, W.; Zeiler, D.; Zihlmann, B.; Zupranski, P.; HERMES Collaboration

2010-01-01

335

Do we understand the single-spin asymmetry for ? 0 inclusive production in pp collisions?  

NASA Astrophysics Data System (ADS)

The cross section data for ?^0 inclusive production in pp collisions is considered in a rather broad kinematic region in energy sqrt{s}, Feynman variable x F and transverse momentum p T. The analysis of these data is done in the perturbative QCD framework at the next-to-leading order. We find that they cannot be correctly described in the entire kinematic domain and this leads us to conclude that the single-spin asymmetry, A N for this process, observed several years ago at FNAL by the experiment E704 and the recent result obtained at BNL-RHIC by STAR, are two different phenomena.

Bourrely, C.; Soffer, J.

2004-08-01

336

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

337

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

NASA Astrophysics Data System (ADS)

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 color center in diamond. We incorporate multipulse 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.

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

2013-12-01

338

Observation of Spin-Orbit Splitting in ? Single-Particle States  

NASA Astrophysics Data System (ADS)

The spin-orbit splitting of ? single-particle states in 13?C was measured. The 13C\\(K-,?- \\)13?C reaction was used to excite both the 1/2- and 3/2- states simultaneously, which have predominantly 12C\\(0+\\)×p? configuration. ? rays from the states to the ground state were measured in coincidence with the ?-'s, by which ls splitting was found to be 152+/-54\\(stat\\)+/-36\\(syst\\) keV. The value is 20-30 times smaller than exhibited by the ls splitting in the nuclear shell model. This value gives us new insight into the YN interaction.

Ajimura, S.; Hayakawa, H.; Kishimoto, T.; Kohri, H.; Matsuoka, K.; Minami, S.; Mori, T.; Morikubo, K.; Saji, E.; Sakaguchi, A.; Shimizu, Y.; Sumihama, M.; Chrien, R. E.; May, M.; Pile, P.; Rusek, A.; Sutter, R.; Eugenio, P.; Franklin, G.; Khaustov, P.; Paschke, K.; Quinn, B. P.; Schumacher, R. A.; Franz, J.; Fukuda, T.; Noumi, H.; Outa, H.; Gan, L.; Tang, L.; Yuan, L.; Tamura, H.; Nakano, J.; Tamagawa, T.; Tanida, K.; Sawafta, R.

2001-05-01

339

Single Spin Asymmetry in High Pt Charged Hadron Production off Nuclei at 40 GeV  

E-print Network

The single transverse spin asymmetry data for the charged hadron production in pC and pCu interactions are presented. The measurements have been performed at FODS-2 experimental setup using 40 GeV/c IHEP polarized proton beam. The hadron transverse momentum range is from 0.5 GeV/c up to 4 GeV/c. The data obtained off the nuclear targets are compared with the proton target data measured earlier with the same experimental setup and with the data of other experiments.

V. V. Abramov; P. I. Goncharov; A. Yu. Kalinin; A. V. Khmelnikov; A. V. Korablev; Yu . P. Korneev; A. V. Kostritsky; A. N. Krinitsyn; V. I. Kryshkin; A. A. Markov; V. V. Talov; L. K. Turchanovich; A. A. Volkov

2004-12-29

340

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

E-print Network

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

Zhong-Bo Kang; Jian-Wei Qiu

2008-12-03

341

Period Halving in a Single-Mode Datta-Das Spin Field Effect Transistor  

NASA Astrophysics Data System (ADS)

We study a nonballistic single-mode Datta-Das spin field effect transistor (SFET) subject to an external magnetic field parallel to the effective Rashba field. We map the SFET to an effective Aharonov-Bohm interferometer (ABI) and use this mapping to demonstrate that when the magnetic field is sufficiently strong, the Rashba-interaction-induced oscillation period of its conductance at sufficiently high temperature becomes a half of its zero temperature value while the temperature-induced period halving does not occur when the magnetic field is sufficiently weak.

Lee, Hyun-Woo; ?ali?kan, S.; Park, Hyowon

2006-09-01

342

Single-spin asymmetries in electroproduction of pions on the longitudinally polarized nucleon targets  

NASA Astrophysics Data System (ADS)

We study the single-spin asymmetries of pions produced in semi-inclusive deep-inelastic scattering on the longitudinally polarized nucleon targets. We particularly consider the effects of the twist-3 transverse-momentum dependent distribution functions fL? and hL to the asymmetry. We calculate the asymmetric moment AULsin?h for ?+, ?-, and ?0 produced off the proton target at HERMES and compare the results with the HERMES data. We also present the prediction of the same asymmetries for different pions at the kinematics of CLAS 5.5 GeV on a proton target, as well as at COMPASS on a deuteron target.

Lu, Zhun

2014-07-01

343

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

E-print Network

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

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

2014-07-02

344

CdSe/ZnSe quantum dot with a single Mn2+ ion—A new system for a single spin manipulation  

NASA Astrophysics Data System (ADS)

We present a magneto-optical study of individual self-assembled CdSe/ZnSe quantum dots doped with single Mn2+ ions. Properties of the studied dots are analyzed analogously to more explored system of Mn-doped CdTe/ZnTe dots. Characteristic sixfold splitting of the neutral exciton emission line as well as its evolution in the magnetic field are described using a spin Hamiltonian model. Dynamics of both exciton recombination and Mn2+ spin relaxation are extracted from a series of time-resolved experiments. Presence of a single dopant is shown not to affect the average excitonic lifetime measured for a number of nonmagnetic and Mn-doped dots. On the other hand, non-resonant pumping is demonstrated to depolarize the Mn2+ spin in a quantum dot placed in external magnetic field. This effect is utilized to determine the ion spin relaxation time in the dark.

Smole?ski, T.

2015-03-01

345

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

SciTech Connect

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

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

2013-01-01

346

Single-Axis Acoustic Levitator With Rotation Control  

NASA Technical Reports Server (NTRS)

Rotation-control equipment simplified. Acoustic levitator with rotation control handles liquid and solid specimens as dense as steel in both low gravity and normal Earth gravity. Levitator is single-axis type.

Trinh, E. H.; Olli, E. E.

1987-01-01

347

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

348

Electric field control of spin dynamics in a magnetically active tunnel junction  

NASA Astrophysics Data System (ADS)

The dynamics of a single spin embedded in a tunnelling junction is studied. Within a nonequilibrium Keldysh Green's function technique, we derive a quantum Langevin equation describing the spin dynamics. In the high temperature limit, it reduces to a Bloch equation, for which the spin relaxation rate, as determined by the temporal fluctuation, is linearly proportional to the temperature. In the opposite limit, the relaxation rate depends on the applied voltage, in contrast to the case of a spin in an equilibrium environment. We also show that spin-flip transition processes during electron tunnelling convert the applied electric field (i.e. voltage bias) into an effective magnetic field. Consequently, the dynamics of the spin, otherwise precessing along the static magnetic field, will have either a frequency shift proportional to the dc bias or a magnetic resonance driven indirectly by an ac electric field at the Larmor frequency ?L. An experiment to measure this effect is also proposed.

Zhu, Jian-Xin; Fransson, Jonas

2006-11-01

349

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

E-print Network

Single Photons Michael N. Leuenberger and Michael E. Flatte´ 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.

350

Elliptic functions and efficient control of Ising spin chainswith unequal couplings  

Microsoft Academic Search

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

Haidong Yuan; Robert Zeier; Navin Khaneja

351

Universal quantum gates on electron-spin qubits with quantum dots inside single-side optical microcavities.  

PubMed

We present some compact quantum circuits for a deterministic quantum computing on electron-spin qubits assisted by quantum dots inside single-side optical microcavities, including the CNOT, Toffoli, and Fredkin gates. They are constructed by exploiting the giant optical Faraday rotation induced by a single-electron spin in a quantum dot inside a single-side optical microcavity as a result of cavity quantum electrodynamics. Our universal quantum gates have some advantages. First, all the gates are accomplished with a success probability of 100% in principle. Second, our schemes require no additional electron-spin qubits and they are achieved by some input-output processes of a single photon. Third, our circuits for these gates are simple and economic. Moreover, our devices for these gates work in both the weak coupling and the strong coupling regimes, and they are feasible in experiment. PMID:24515020

Wei, Hai-Rui; Deng, Fu-Guo

2014-01-13

352

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

PubMed

Nitrogen-vacancy (NV) center in diamond is a promising quantum metrology tool finding applications across disciplines. The spin sensor measures magnetic fields, electric fields and temperature with nano-scale precision and is fully operable under ambient conditions. Moreover, it achieves precision scaling inversely with total measurement time ?B ? 1/T (Heisenberg scaling) rather than as the inverse of the square root of T, with ?B = ?T the Shot-Noise limit. This scaling can be achieved by means of phase estimation algorithms (PEAs), in combination with single-shot read-out. Despite their accuracy, the range of applicability of PEAs is limited to sensing single frequencies with negligible temporal fluctuations. Nuclear Magnetic Resonance (NMR) signals from molecules often contain multifrequency components and sensing them using PEA is ruled out. Here we propose an alternative method for precision magnetometry in frequency multiplexed signals via compressive sensing (CS) techniques focusing on nanoscale NMR. We show that CS can provide for precision scaling approximately as ?B ? 1/T, as well as for a 5-fold increase in sensitivity over dynamic-range gain, in addition to reducing the total number of resources required. We illustrate our method by taking model solid-state spectra of Glycine acquired under Magic Angle Spinning conditions. PMID:24728454

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

2014-01-01

353

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

354

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

PubMed Central

Nitrogen-vacancy (NV) center in diamond is a promising quantum metrology tool finding applications across disciplines. The spin sensor measures magnetic fields, electric fields and temperature with nano-scale precision and is fully operable under ambient conditions. Moreover, it achieves precision scaling inversely with total measurement time ?B ? 1/T (Heisenberg scaling) rather than as the inverse of the square root of T, with the Shot-Noise limit. This scaling can be achieved by means of phase estimation algorithms (PEAs), in combination with single-shot read-out. Despite their accuracy, the range of applicability of PEAs is limited to sensing single frequencies with negligible temporal fluctuations. Nuclear Magnetic Resonance (NMR) signals from molecules often contain multifrequency components and sensing them using PEA is ruled out. Here we propose an alternative method for precision magnetometry in frequency multiplexed signals via compressive sensing (CS) techniques focusing on nanoscale NMR. We show that CS can provide for precision scaling approximately as ?B ? 1/T, as well as for a 5-fold increase in sensitivity over dynamic-range gain, in addition to reducing the total number of resources required. We illustrate our method by taking model solid-state spectra of Glycine acquired under Magic Angle Spinning conditions. PMID:24728454

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

2014-01-01

355

Electric field control of spin rotation in bilayer graphene.  

PubMed

The manipulation of the electron spin degree of freedom is at the core of the spintronics paradigm, which offers the perspective of reduced power consumption, enabled by the decoupling of information processing from net charge transfer. Spintronics also offers the possibility of devising hybrid devices able to perform logic, communication, and storage operations. Graphene, with its potentially long spin-coherence length, is a promising material for spin-encoded information transport. However, the small spin-orbit interaction is also a limitation for the design of conventional devices based on the canonical Datta-Das spin field-effect transistors. An alternative solution can be found in magnetic doping of graphene or, as discussed in the present work, in exploiting the proximity effect between graphene and ferromagnetic oxides (FOs). Graphene in proximity to FO experiences an exchange proximity interaction, that acts as an effective Zeeman field for electrons in graphene, inducing a spin precession around the magnetization axis of the FO. Here we show that in an appropriately designed double-gate field-effect transistor, with a bilayer graphene channel and FO used as a gate dielectric, spin-precession of carriers can be turned ON and OFF with the application of a differential voltage to the gates. This feature is directly probed in the spin-resolved conductance of the bilayer. PMID:20929246

Michetti, Paolo; Recher, Patrik; Iannaccone, Giuseppe

2010-11-10

356

Electric control of the spin Hall effect by intervalley transitions  

E-print Network

., & Jungwirth T. Spin-injection Hall effect in a planar photovoltaic cell Nature Phys. 5, 675 (2009). 24 Wunderlich, J., Park, B. G., Irvine, A. C., Zarbo, L. P. , Rozkotova, E., Nemec, P., Novak, V., Sinova, J., & Jungwirth, T. Spin Hall effect transistor...

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

2014-08-10

357

Stark shift control of single optical centers in diamond  

E-print Network

Lifetime limited optical excitation lines of single nitrogen vacancy (NV) defect centers in diamond have been observed at liquid helium temperature. They display unprecedented spectral stability over many seconds and excitation cycles. Spectral tuning of the spin selective optical resonances was performed via the application of an external electric field (i.e. the Stark shift). A rich variety of Stark shifts were observed including linear as well as quadratic components. The ability to tune the excitation lines of single NV centers has potential applications in quantum information processing.

Ph. Tamarat; T. Gaebel; J. R. Rabeau; M. Khan; A. D. Greentree; H. Wilson; L. C. L. Hollenberg; S. Prawer; P. Hemmer; F. Jelezko; J. Wrachtrup

2006-07-25

358

Noise-compensating pulses for electrostatically controlled silicon spin qubits  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

359

Polarization control at spin-driven ferroelectric domain walls.  

PubMed

Unusual electronic states arise at ferroelectric domain walls due to the local symmetry reduction, strain gradients and electrostatics. This particularly applies to improper ferroelectrics, where the polarization is induced by a structural or magnetic order parameter. Because of the subordinate nature of the polarization, the rigid mechanical and electrostatic boundary conditions that constrain domain walls in proper ferroics are lifted. Here we show that spin-driven ferroelectricity promotes the emergence of charged domain walls. This provides new degrees of flexibility for controlling domain-wall charges in a deterministic and reversible process. We create and position a domain wall by an electric field in Mn0.95Co0.05WO4. With a magnetic field we then rotate the polarization and convert neutral into charged domain walls, while its magnetic properties peg the wall to its location. Using atomistic Landau-Lifshitz-Gilbert simulations we quantify the polarization changes across the two wall types and highlight their general occurrence. PMID:25868608

Leo, Naëmi; Bergman, Anders; Cano, Andres; Poudel, Narayan; Lorenz, Bernd; Fiebig, Manfred; Meier, Dennis

2015-01-01

360

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

Microsoft Academic Search

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

Amit K. Sanyal; Christopher Moseley; Anthony Bloch

361

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

362

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

363

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

PubMed

We report the first measurement of the transverse momentum dependence of double-spin asymmetries in semi-inclusive production of pions in deep-inelastic scattering off the longitudinally polarized proton. Data have been obtained using a polarized electron beam of 5.7 GeV with the CLAS detector at the Jefferson Lab (JLab). Modulations of single spin asymmetries over the azimuthal angle between lepton scattering and hadron production planes ? have been measured over a wide kinematic range in Bjorken x and virtual photon squared four-momentum Q2. A significant nonzero sin2? single spin asymmetry was observed for the first time indicating strong spin-orbit correlations for transversely polarized quarks in the longitudinally polarized proton. PMID:21231647

Avakian, H; Bosted, P; Burkert, V D; Elouadrhiri, L; Adhikari, K P; Aghasyan, M; Amaryan, M; Anghinolfi, M; Baghdasaryan, H; Ball, J; Battaglieri, M; Bedlinskiy, I; Biselli, A S; Branford, D; Briscoe, W J; Brooks, W; Carman, D S; Casey, L; Cole, P L; Collins, P; Crabb, D; Crede, V; D'Angelo, A; Daniel, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Dey, B; Dhamija, S; Dickson, R; Djalali, C; Dodge, G; Doughty, D; Dupre, R; El Alaoui, A; Eugenio, P; Fegan, S; Fersch, R; Forest, T A; Fradi, A; Gabrielyan, M Y; Gavalian, G; Gevorgyan, N; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Gohn, W; Gothe, R W; Griffioen, K A; Guidal, M; Guler, N; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Hassall, N; Heddle, D; Hicks, K; Holtrop, M; Ilieva, Y; Ireland, D G; Isupov, E L; Jawalkar, S S; Jo, H S; Joo, K; Keller, D; Khandaker, M; Khetarpal, P; Kim, W; Klein, A; Klein, F J; Konczykowski, P; Kubarovsky, V; Kuhn, S E; Kuleshov, S V; Kuznetsov, V; Livingston, K; Lu, H Y; Markov, N; Mayer, M; Martinez, D; McAndrew, J; McCracken, M E; McKinnon, B; Meyer, C A; Mineeva, T; Mirazita, M; Mokeev, V; Moreno, B; Moriya, K; Morrison, B; Moutarde, H; Munevar, E; Nadel-Turonski, P; Nasseripour, R; Niccolai, S; Niculescu, G; Niculescu, I; Niroula, M R; Osipenko, M; Ostrovidov, A I; Paremuzyan, R; Park, K; Park, S; Pasyuk, E; Pereira, S Anefalos; Perrin, Y; Pisano, S; Pogorelko, O; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Raue, B A; Ricco, G; Ripani, M; Rosner, G; Rossi, P; Sabatié, F; Saini, M S; Salamanca, J; Salgado, C; Schumacher, R A; Seder, E; Seraydaryan, H; Sharabian, Y G; Sober, D I; Sokhan, D; Stepanyan, S S; Stepanyan, S; Stoler, P; Strauch, S; Suleiman, R; Taiuti, M; Tedeschi, D J; Tkachenko, S; Ungaro, M; Vernarsky, B; Vineyard, M F; Voutier, E; Watts, D P; Weinstein, L B; Weygand, D P; Wood, M H; Zhang, J; Zhao, B; Zhao, Z W

2010-12-31

364

Spin-orbit controlled quantum capacitance of a polar heterostructure  

NASA Astrophysics Data System (ADS)

Oxide heterostructures with polar films display special electronic properties, such as the electronic reconstruction at their internal interfaces with the formation of two-dimensional metallic states. Moreover, the electrical field from the polar layers is inversion-symmetry breaking and generates a Rashba spin-orbit coupling (RSOC) in the interfacial electronic system. We investigate the quantum capacitance of a heterostructure in which a sizable RSOC at a metallic interface is controlled by the electric field of a surface electrode. Such a structure is, for example, given by a LaAlO3 film on a SrTiO3 substrate which is gated by a top electrode. Such heterostructures can exhibit a strong enhancement of their capacitance [Li et al., Science 332, 825 (2011), 10.1126/science.1204168]. The capacitance is related to the electronic compressibility of the heterostructure, but the two quantities are not equivalent. In fact, the transfer of charge to the interface controls the relation between capacitance and compressibility. We find that, due to a strong RSOC, the quantum capacitance can be larger than the classical geometric value. However, in contrast to the results of recent investigations [Caprara et al., Phys. Rev. Lett. 109, 196401 (2012), 10.1103/PhysRevLett.109.196401;Bucheli et al., Phys. Rev. B 89, 195448 (2014), 10.1103/PhysRevB.89.195448; Seibold et al., Europhys. Lett. 109, 17006 (2015), 10.1209/0295-5075/109/17006], the compressibility does not become negative for realistic parameter values for LaAlO3/SrTiO3 and, therefore, we find that no phase-separated state is induced by the strong RSOC at these interfaces.

Steffen, Kevin; Loder, Florian; Kopp, Thilo

2015-02-01

365

Single-Chip Microcomputer Control Of The PWM Inverter  

NASA Astrophysics Data System (ADS)

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

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

1987-10-01

366

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

SciTech Connect

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

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

2010-07-15

367

Controlling spin-wave propagation with Oersted fields  

NASA Astrophysics Data System (ADS)

The goal of magnon spintronics is to utilize the coherent propagation of spin waves for low-power data processing. Spin waves carry angular momentum and can transport spin information over distances much larger than the spin diffusion length of metals. However, in thin magnetic films the highly anisotropic dispersion relation leads to strong changes in the spin-wave energy for different angles between their propagation direction and the magnetization orientation. Consequently, spin waves only travel along a straight path if the magnetization direction is fixed by a global external magnetic field. We demonstrate that locally rotating magnetic fields generated via electric current pulses allow to vary the propagation direction of spin waves. Using spatially resolved Brillouin light scattering microscopy the propagation behavior was directly verified.footnotetextK. Vogt, H. Schultheiss, S. Jain, J.E. Pearson, A. Hoffmann, S.D. Bader, and B. Hillebrands, Appl. Phys. Lett. 101, 042410 (2012) We have modeled the current generated magnetic fields with a finite element code and calculated the magnetic response using micro magnetic simulations.

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

2013-03-01

368

Control of electron spin-orbit anisotropy in pyramidal InAs quantum dots  

NASA Astrophysics Data System (ADS)

We investigate the electron spin-orbit interaction anisotropy of pyramidal InAs quantum dots using a fully three-dimensional Hamiltonian. The dependence of the spin-orbit interaction strength on the orientation of externally applied in-plane magnetic fields is consistent with recent experiments, and it can be explained from the interplay between Rashba and Dresselhaus spin-orbit terms in dots with asymmetric confinement. Based on this, we propose manipulating the dot composition and height as efficient means for controlling the spin-orbit anisotropy.

Segarra, C.; Planelles, J.; Climente, J. I.

2015-02-01

369

Gate-controlled spin-orbit quantum interference effects in lateral transport.  

PubMed

In situ control of spin-orbit coupling in coherent transport using a clean GaAs/AlGaAs two-dimensional electron gas is realized, leading to a gate-tunable crossover from weak localization to antilocalization. The necessary theory of 2D magnetotransport in the presence of spin-orbit coupling beyond the diffusive approximation is developed and used to analyze experimental data. With this theory the Rashba contribution and linear and cubic Dresselhaus contributions to spin-orbit coupling are separately estimated, allowing the angular dependence of spin-orbit precession to be extracted at various gate voltages. PMID:12633263

Miller, J B; Zumbühl, D M; Marcus, C M; Lyanda-Geller, Y B; Goldhaber-Gordon, D; Campman, K; Gossard, A C

2003-02-21

370

Conditional control of donor nuclear spins in silicon using Stark shifts  

E-print Network

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.

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

2014-05-28

371

Antiferromagnet-controlled spin current transport in SrMnO3/Pt hybrids  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

372

Single-chip microcontrollers for switchgear control  

NASA Technical Reports Server (NTRS)

A switchgear controller utilizing a microcontroller is described. The primary goal was to mimic the functions and performance of the generic controller board with a microcontroller board which will cause the power automation system to consume less power. The code for the microcontroller implementation on a development board has been developed, and the signal conditioning for the signals to the microcontroller has been designed and tested. The implementation of this decision system for data gathering, command control, fault detection, and circuit protection, when compared to other implementations, provides more functions and better response while reducing weight, volume, and power consumption.

Watson, Karan; Russell, B. Don; Jagadish, Usha

1991-01-01

373

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

374

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

375

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

376

Phase-controllable spin wave generation in iron garnet by linearly polarized light pulses  

NASA Astrophysics Data System (ADS)

A phase-controlled spin wave was non-thermally generated in bismuth-doped rare-earth iron garnet by linearly polarized light pulses. We controlled the initial phase of the spin wave continuously within a range of 180° by changing the polarization azimuth of the excitation light. The azimuth dependences of the initial phase and amplitude of the spin wave were attributed to a combination of the inverse Cotton-Mouton effect and photoinduced magnetic anisotropy. Temporally and spatially resolved spin wave propagation was observed with a CCD camera, and the waveform was in good agreement with calculations. A nonlinear effect of the spin excitation was observed for excitation fluences higher than 100 mJ/cm2.

Yoshimine, Isao; Satoh, Takuya; Iida, Ryugo; Stupakiewicz, Andrzej; Maziewski, Andrzej; Shimura, Tsutomu

2014-07-01

377

Gate-controlled spin splitting in GaN /AlN quantum wells  

NASA Astrophysics Data System (ADS)

The spin splitting of wurtzite GaN was calculated by 32×32 Hamiltonian with spin-orbital interaction. The band-folding effect generates two conduction bands ?C1 and ?C3 in which the p-wave probability shows a tremendous change when kz approaches the anticrossing zone. We found that a large spin plitting in GaN /AlN quantum wells is produced due to ?C1-?C3 coupling, and is effectively controlled by electric field. Based on the mechanism and gate-controllable spin splitting, we proposed a p-wave-enhanced quantum well, InxGa1-xN /InyAl1-yN, for the application of the spin-polarized field effect transistor designed by Datta and Das [Appl. Phys. Lett. 56, 665 (1990)].

Lo, Ikai; Wang, W. T.; Gau, M. H.; Tsai, J. K.; Tsay, S. F.; Chiang, J. C.

2006-02-01

378

Phase-controllable spin wave generation in iron garnet by linearly polarized light pulses  

SciTech Connect

A phase-controlled spin wave was non-thermally generated in bismuth-doped rare-earth iron garnet by linearly polarized light pulses. We controlled the initial phase of the spin wave continuously within a range of 180° by changing the polarization azimuth of the excitation light. The azimuth dependences of the initial phase and amplitude of the spin wave were attributed to a combination of the inverse Cotton-Mouton effect and photoinduced magnetic anisotropy. Temporally and spatially resolved spin wave propagation was observed with a CCD camera, and the waveform was in good agreement with calculations. A nonlinear effect of the spin excitation was observed for excitation fluences higher than 100 mJ/cm{sup 2}.

Yoshimine, Isao; Iida, Ryugo; Shimura, Tsutomu [Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505 (Japan); Satoh, Takuya, E-mail: satoh@phys.kyushu-u.ac.jp [Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505 (Japan); PRESTO, Japan Science and Technology Agency, Tokyo 102-0076 (Japan); Department of Physics, Kyushu University, Fukuoka 812-8581 (Japan); Stupakiewicz, Andrzej; Maziewski, Andrzej [Laboratory of Magnetism, Faculty of Physics, University of Bialystok, Bialystok 15-424 (Poland)

2014-07-28

379

Controlling the spins angular momentum in ferromagnets with sequences of picosecond acoustic pulses.  

PubMed

Controlling the angular momentum of spins with very short external perturbations is a key issue in modern magnetism. For example it allows manipulating the magnetization for recording purposes or for inducing high frequency spin torque oscillations. Towards that purpose it is essential to modify and control the angular momentum of the magnetization which precesses around the resultant effective magnetic field. That can be achieved with very short external magnetic field pulses or using intrinsically coupled magnetic structures, resulting in a transfer of spin torque. Here we show that using picosecond acoustic pulses is a versatile and efficient way of controlling the spin angular momentum in ferromagnets. Two or three acoustic pulses, generated by femtosecond laser pulses, allow suppressing or enhancing the magnetic precession at any arbitrary time by precisely controlling the delays and amplitudes of the optical pulses. A formal analogy with a two dimensional pendulum allows us explaining the complex trajectory of the magnetic vector perturbed by the acoustic pulses. PMID:25687970

Kim, Ji-Wan; Vomir, Mircea; Bigot, Jean-Yves

2015-01-01

380

Controlling the Spins Angular Momentum in Ferromagnets with Sequences of Picosecond Acoustic Pulses  

PubMed Central

Controlling the angular momentum of spins with very short external perturbations is a key issue in modern magnetism. For example it allows manipulating the magnetization for recording purposes or for inducing high frequency spin torque oscillations. Towards that purpose it is essential to modify and control the angular momentum of the magnetization which precesses around the resultant effective magnetic field. That can be achieved with very short external magnetic field pulses or using intrinsically coupled magnetic structures, resulting in a transfer of spin torque. Here we show that using picosecond acoustic pulses is a versatile and efficient way of controlling the spin angular momentum in ferromagnets. Two or three acoustic pulses, generated by femtosecond laser pulses, allow suppressing or enhancing the magnetic precession at any arbitrary time by precisely controlling the delays and amplitudes of the optical pulses. A formal analogy with a two dimensional pendulum allows us explaining the complex trajectory of the magnetic vector perturbed by the acoustic pulses. PMID:25687970

Kim, Ji-Wan; Vomir, Mircea; Bigot, Jean-Yves

2015-01-01

381

Controlling the Spins Angular Momentum in Ferromagnets with Sequences of Picosecond Acoustic Pulses  

NASA Astrophysics Data System (ADS)

Controlling the angular momentum of spins with very short external perturbations is a key issue in modern magnetism. For example it allows manipulating the magnetization for recording purposes or for inducing high frequency spin torque oscillations. Towards that purpose it is essential to modify and control the angular momentum of the magnetization which precesses around the resultant effective magnetic field. That can be achieved with very short external magnetic field pulses or using intrinsically coupled magnetic structures, resulting in a transfer of spin torque. Here we show that using picosecond acoustic pulses is a versatile and efficient way of controlling the spin angular momentum in ferromagnets. Two or three acoustic pulses, generated by femtosecond laser pulses, allow suppressing or enhancing the magnetic precession at any arbitrary time by precisely controlling the delays and amplitudes of the optical pulses. A formal analogy with a two dimensional pendulum allows us explaining the complex trajectory of the magnetic vector perturbed by the acoustic pulses.

Kim, Ji-Wan; Vomir, Mircea; Bigot, Jean-Yves

2015-02-01

382

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

SciTech Connect

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

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

2011-10-15

383

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

PubMed

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

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

2013-09-01

384

PUBLISHED ONLINE: 11 OCTOBER 2009 | DOI: 10.1038/NPHYS1424 Universal quantum control of two-electron spin  

E-print Network

electron spins where the rapid exchange of the two electrons permits electrically controllable rotations magnitude, we achieve full quantum control of the two-electron logical spin qubit with nanosecond operation-level quantum bit (smallest logical unit of the quantum computer) is encoded in the spin state of two electrons

Loss, Daniel

385

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

SciTech Connect

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

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

1980-01-01

386

Observation of spin-orbit splitting in lambda single-particle states.  

PubMed

The spin-orbit splitting of Lambda single-particle states in (13)(Lambda)C was measured. The 13C(K-,pi(-))(13)(Lambda)C reaction was used to excite both the 1/2(-) and 3/2(-) states simultaneously, which have predominantly 12C(0(+)) x p(Lambda) configuration. gamma rays from the states to the ground state were measured in coincidence with the pi(-)'s, by which ls splitting was found to be 152+/-54(stat)+/-36(syst) keV. The value is 20-30 times smaller than exhibited by the ls splitting in the nuclear shell model. This value gives us new insight into the YN interaction. PMID:11328148

Ajimura, S; Hayakawa, H; Kishimoto, T; Kohri, H; Matsuoka, K; Minami, S; Mori, T; Morikubo, K; Saji, E; Sakaguchi, A; Shimizu, Y; Sumihama, M; Chrien, R E; May, M; Pile, P; Rusek, A; Sutter, R; Eugenio, P; Franklin, G; Khaustov, P; Paschke, K; Quinn, B P; Schumacher, R A; Franz, J; Fukuda, T; Noumi, H; Outa, H; Gan, L; Tang, L; Yuan, L; Tamura, H; Nakano, J; Tamagawa, T; Tanida, K; Sawafta, R

2001-05-01

387

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

E-print Network

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

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

2015-02-06

388

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

389

Increasing the coherence time of single electron spins in diamond by high temperature annealing  

E-print Network

Negatively charged Nitrogen-Vacancy (NV$^-$) centers in diamond produced by ion implantation often show properties different from NVs created during the crystal growth. We observe that NVs created from nitrogen ions with four different energies (30-300 keV) show much shorter electron spin coherence time $T_2$ compared to the "natural" NVs and we could find any dependence of $T_2$ on the implantation energy. Moreover, we also find out that about 10% of them show switching from NV$^-$to NV$^0$. We develop a method to increase $T_2$ of single NV$^-$ centers by annealing the sample at $t=1200 {\\circ}$C whereas at the same time the fraction of the NVs showing discharging is greatly reduced.

Boris Naydenov; Friedemann Reinhard; Anke Lämmle; V. Richter; Rafi Kalish; Ulrika F. S. D'Haenens-Johansson; Mark Newton; Fedor Jelezko; Jörg Wrachtrup

2010-12-01

390

Electrical control of spin dynamics in spin-orbit coupled ferromagnets  

E-print Network

in the lattice could be used, 22 Chapter 2: Theoretical background introducing larger lattice electric potentials. (Ga,Mn)Sb substitutes the Arsenide ions for Antimony, increasing the spin-orbit energy splitting by ?2.5 times.121 (Ga,Mn)Sb has been grown by MBE...

Skinner, Timothy

2015-01-06

391

The artificial satellite observation chronograph controlled by single chip microcomputer  

Microsoft Academic Search

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

Guangrong Pan; Jufan Tan; Yuanjun Ding

1991-01-01

392

The artificial satellite observation chronograph controlled by single chip microcomputer.  

NASA Astrophysics Data System (ADS)

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

Pan, Guangrong; Tan, Jufan; Ding, Yuanjun

1991-06-01

393

A single current sensor control technique for induction motors  

Microsoft Academic Search

This paper describes a single current sensor control technique for induction motors that uses only a single DC-link current sensing resistor to obtain the information of three line currents. The principal motivation is to reduce the cost, and improve the reliability of a drive system. However, in certain conditions, the measurement is distorted due to the too narrow current pulse

Chunpeng Zhang; Fei Lin

2002-01-01

394

GAS GENERATOR ACTUATOR ARRAYS FOR FLIGHT CONTROL OF SPINNING BODY PROJECTILES  

E-print Network

for integration of these GGAs into a 40-mm diameter gun-launched projectile for projectile flight controlGAS GENERATOR ACTUATOR ARRAYS FOR FLIGHT CONTROL OF SPINNING BODY PROJECTILES Brian A. English2 delivering the impulse. The arrays of GGAs are connected with control electronics and integrated into a 40-mm

395

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

396

Control of spin-wave excitations in deterministic fractals  

NASA Astrophysics Data System (ADS)

We study spin-wave spectra of mesoscopic ferromagnetic Sierpinski carpets by means of broadband-ferromagnetic resonance measurements and micromagnetic simulations. Sierpinski carpets are self-similar fractals with noninteger Hausdorff dimension that are constructed via a deterministic iteration process. The number of quantized spin-wave modes in the spectra increases with the iteration level of the carpets and the frequency splitting resembles bandpass characteristics known from fractal antennas. We find that the splitting is sensitive to the fractal dimension as well as to the relative alignment of the magnetic field and the sides of the fractals. Micromagnetic simulations provide the localization of individual spin-wave modes determined by the confinement and the inhomogeneity of the internal field.

Swoboda, Christian; Martens, Michael; Meier, Guido

2015-02-01

397

Controlled transport through a single molecule.  

PubMed

We demonstrate how an electrode-molecule-electrode junction can be controllably opened and closed by careful tuning of the contacts' interspace and voltage. The molecule, an octanethiol, flips to bridge a ~1 nm interspace between substrate and scanning tunnelling microscope tip when an electric field exceeds a threshold (switch 'on'). Reducing the field below this threshold value leads to the reproducible detachment of the octanethiol (switch 'off'). Once contacted, a further reduction of the contacts' interspace leads to an increase of the conductance of the molecule. PMID:22311709

Kumar, A; Heimbuch, R; Poelsema, B; Zandvliet, H J W

2012-02-29

398

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

SciTech Connect

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

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

2008-01-01

399

Time-optimal monotonically convergent algorithm with an application to the control of spin systems  

NASA Astrophysics Data System (ADS)

We present a new formulation of monotonically convergent algorithms which allows us to optimize both the control duration and the field fluence. A standard algorithm designs a control field of fixed duration, which both brings the system close to the target state and minimizes its fluence, whereas here we include in addition the optimization of the duration in the cost functional. We apply this new algorithm to the control of spin systems in nuclear magnetic resonance. We show how to implement controlled-not gates in systems of two and four coupled spins.

Lapert, M.; Salomon, J.; Sugny, D.

2012-03-01

400

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

NASA Technical Reports Server (NTRS)

Some fundamental information on control system effects on controllability of highly maneuverable aircraft at high angles of attack are summarized as well as techniques for enhancing fighter aircraft departure/spin resistance using control system design. The discussion includes: (1) a brief review of pertinent high angle of attack phenomena including aerodynamics, inertia coupling, and kinematic coupling; (2) effects of conventional stability augmentation systems at high angles of attack; (3) high angle of attack control system concepts designed to enhance departure/spin resistance; and (4) the outlook for applications of these concepts to future fighters, particularly those designs which incorporate relaxed static stability.

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

1980-01-01

401

Microscopy beyond the diffraction limit using actively controlled single molecules  

PubMed Central

Summary In this short review, the general principles are described for obtaining microscopic images with resolution beyond the optical diffraction limit with single molecules. Although it has been known for several decades that single-molecule emitters can blink or turn on and off, in recent work the addition of on/off control of molecular emission to maintain concentrations at very low levels in each imaging frame combined with sequential imaging of sparse subsets has enabled the reconstruction of images with resolution far below the optical diffraction limit. Single-molecule active control microscopy provides a powerful window into information about nanoscale structures that was previously unavailable. PMID:22582796

MOERNER, W.E.

2013-01-01

402

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

SciTech Connect

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

Raboin, P. J., LLNL

1998-03-10

403

Spin canting, metamagnetism, and single-chain magnetic behaviour in a cyano-bridged homospin iron(II) compound.  

PubMed

Spin canting, antiferromagnetic ordering, metamagnetism and single-chain magnetism were verified in a cyano-bridged Fe(II) compound synthesized from the pentagonal bipyramidal Fe(II) starting material in the presence of excessive BF4(-) anions. PMID:25600433

Shao, Dong; Zhang, Shao-Liang; Zhao, Xin-Hua; Wang, Xin-Yi

2015-03-14

404

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

NASA Astrophysics Data System (ADS)

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

Gingrich, Eric C.

405

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

E-print Network

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

Randeria, Mallika

2012-01-01

406

Robust control of entanglement in a Nitrogen-vacancy centre coupled to a Carbon-13 nuclear spin in diamond  

E-print Network

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

407

Nonredundant Single-Gimbaled Control Moment Gyroscopes Timothy A. Sands,  

E-print Network

Nonredundant Single-Gimbaled Control Moment Gyroscopes Timothy A. Sands, Jae Jun Kim, and Brij N configuration. Next, momentum space reshaping is shown via mixed skew angles permitting orientation of maximum, a decoupled gimbal angle calculation technique is shown to avoid loss of attitude control associated

408

Control of vibrational states by spin-polarized transport in a carbon nanotube resonator  

NASA Astrophysics Data System (ADS)

We study spin-dependent transport in a suspended carbon nanotube quantum dot in contact with two ferromagnetic leads and with the dot's spin coupled to the flexural mechanical modes. The spin-vibration interaction induces spin-flip processes between the two energy levels of the dot. This interaction arises from the spin-orbit coupling or a magnetic field gradient. The inelastic vibration-assisted spin flips give rise to a mechanical damping and, for an applied bias voltage, to a steady nonequilibrium occupation of the harmonic oscillator. We analyze these effects as function of the energy-level separation of the dot and the magnetic polarization of the leads. Depending on the magnetic configuration and the bias-voltage polarity, we can strongly cool a single mode or pump energy into it. In the latter case, we find that within our approximation, the system approaches eventually a regime of mechanical instability. Furthermore, owing to the sensitivity of the electron transport to the spin orientation, we find signatures of the nanomechanical motion in the current-voltage characteristic. Hence, the vibrational state can be read out in transport measurements.

Stadler, P.; Belzig, W.; Rastelli, G.

2015-02-01

409

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

PubMed

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

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

2003-06-20

410

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

SciTech Connect

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

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

2013-12-16

411

Electrically controlled transfer of spin angular momentum of light in an optically active medium  

NASA Astrophysics Data System (ADS)

Spin is an intrinsic property of the photon. A method for using an externally applied dc electric field to manipulate the transfer of spin angular momentum of light in an optically active medium is presented. To discuss this, we first develop a wave coupling theory of the mutual action of natural optical activity and the linear electro-optic effect. Besides being used for analyzing the electrically controlled transfer of spin angular momentum of light, the theory can also be used to describe the propagation of light traveling along an arbitrary direction in any optically active medium with an external dc electric field along an arbitrary direction.

Chen, Lixiang; Zheng, Guoliang; Xu, Jie; Zhang, Bingzhi; She, Weilong

2006-12-01

412

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

NASA Astrophysics Data System (ADS)

We studied the spin-polarized electron transport in oxygen-incorporated Au, Cu, and Fe single-atom chains (SACs) by first-principles calculations. We first investigated the mechanism responsible for the low conductance (<1G0) of the Au and Cu SACs in an oxygen environment reported in recent experiments. We found that for the Au SACs, the low conductance plateau around 0.6G0 can be attributed to a distorted chain doped with a single oxygen atom, while the 0.1G0 conductance comes from a linear chain incorporated with an oxygen molecule and is caused by an antibonding state formed by oxygen's occupied frontier orbital with dz orbitals of adjacent Au atoms. For the Cu SACs, the conductance about 0.3G0 is ascribed to a special configuration that contains Cu and O atoms in an alternating sequence. This exhibits an even-odd conductance oscillation with an amplitude of ˜0.1G0. In contrast, for the alternating Fe-O SACs, conductance overall decreases with an increase in O atoms and it approaches nearly zero for the chain with more than four O atoms. While the Cu-O SACs behave as perfect spin filters for one spin channel due to the half metallic nature, the Fe-O SACs can serve as perfect spin filters for two spin channels depending on the polarity of the applied gate voltage.

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

2015-01-01

413

A single neuron PID control for twin rotor MIMO system  

Microsoft Academic Search

This paper presents an intelligent control scheme which utilizes a single neuron PID controller to an experimental propeller setup called the twin rotor multi-input multi-output system (TRMS). The control objective is to make the TRMS move quickly and accurately to the desired attitudes. The pitch angle and the azimuth angle in the conditions of decoupled and cross-coupled between vertical and

Ting-Kai Liu; Jih-Gau Juang

2009-01-01

414

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

Microsoft Academic Search

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

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

2006-01-01

415

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

NASA Astrophysics Data System (ADS)

We report precision measurements of the Feynman x (xF) dependence, and first measurements of the transverse momentum (pT) dependence, of transverse single-spin asymmetries for the production of ?0 mesons from polarized proton collisions at s=200GeV. The xF dependence of the results is in fair agreement with perturbative QCD model calculations that identify orbital motion of quarks and gluons within the proton as the origin of the spin effects. Results for the pT dependence at fixed xF are not consistent with these same perturbative QCD-based calculations.

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

2008-11-01

416

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

NASA Astrophysics Data System (ADS)

Single antidot as a passive point excitation source has been implemented to create caustic spin-wave beams in yttrium iron garnet film. Diffraction of surface magnetostatic spin waves from such antidot is investigated experimentally and theoretically. Our experimental results from Brillouin light scattering spectroscopy indicate that the diffraction beams, which manifest as reflection, extinction, and semicaustic lines, are tunable by the frequency and direction of the incident wave. Numerical calculations are in good agreement with the experimental findings and explain the directions of caustic beams caused by the diffraction.

Gieniusz, R.; Ulrichs, H.; Bessonov, V. D.; Guzowska, U.; Stognii, A. I.; Maziewski, A.

2013-03-01

417

Interlocking control by Distributed Signal Boxes: design and verification with the SPIN model checker  

E-print Network

1 Interlocking control by Distributed Signal Boxes: design and verification with the SPIN model control design is applied to a railway- interlocking problem and more precisely, to the Athens underground metro sys- tem. Signal boxes correspond to the network's interlocking points and commu- nicate only

Katsaros, Panagiotis

418

Magnetic field controlled FZ single crystal growth of intermetallic compounds  

Microsoft Academic Search

Intermetallic rare-earth-transition-metal compounds with their coexistence of magnetic ordering and superconductivity are still of great scientific interest. The crystal growth of bulk single crystals is very often unsuccessful due to an unfavorable solid–liquid interface geometry enclosing concave fringes. The aim of the work is the contactless control of heat and material transport during floating-zone single crystal growth of intermetallic compounds.

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

2005-01-01

419

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

SciTech Connect

The cause for the preferred spin orientation in magnetic systems containing spin-1/2 transition-metal ions was explored by studying the origin of the easy-plane anisotropy of the spin-1/2 Cu{sup 2+} ions in CuCl{sub 2}·2H{sub 2}O, LiCuVO{sub 4}, CuCl{sub 2}, and CuBr{sub 2} on the basis of density functional theory and magnetic dipole-dipole energy calculations as well as a perturbation theory treatment of the spin-orbit coupling. We find that the spin orientation observed for these spin-1/2 ions is not caused by their anisotropic spin exchange interactions, nor by their magnetic dipole-dipole interactions, but by the spin-orbit coupling associated with their crystal-field split d-states. Our study also predicts in-plane anisotropy for the Cu{sup 2+} ions of Bi{sub 2}CuO{sub 4} and Li{sub 2}CuO{sub 2}. The results of our investigations dispel the mistaken belief that magnetic systems with spin-1/2 ions have no magnetic anisotropy induced by spin-orbit coupling.

Liu, Jia; Whangbo, Myung-Hwan, E-mail: hxiang@fudan.edu.cn, E-mail: mike-whangbo@ncsu.edu [Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695 (United States); Koo, Hyun-Joo [Department of Chemistry and Research Institute for Basic Sciences, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Xiang, Hongjun, E-mail: hxiang@fudan.edu.cn, E-mail: mike-whangbo@ncsu.edu [Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433 (China); Kremer, Reinhard K. [Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany)

2014-09-28

420

Morphologic parameters of normal swallowing events using single-shot fast spin echo dynamic MRI.  

PubMed

This study was designed to determine visible and measurable morphological parameters in normal swallowing using dynamic MRI with single-shot fast spin echo (SSFSE), as a preliminary study in view of noninvasive MRI swallowing evaluation in patients with dysphagia. Seven healthy volunteers aged 24-40 underwent dynamic MRI with SSFSE, with a 1.5-T unit, using a head and neck antenna. Patients repeated dry swallow, water swallow, marshmallow swallow, cake swallow, and cookie chewing for a total of five series, with 15 acquisitions per series at a rate of 700 ms per acquisition. A checklist of swallowing events and anatomic landmarks was used to determine which anatomic landmarks are always visible, which phases or swallowing movements are always visible, and which landmarks can be used to measure oral and pharyngeal motion in swallowing. The oral preparatory, oral, and oropharyngeal phases of deglutition were visible in all cases. No aspiration, reflux, or abnormal residue was observed. Spatial resolution allowed for anatomical measurements of laryngeal elevation, oropharyngeal diameter, and tongue base and velum displacement in all cases. SSFSE dynamic MRI is pertinent for evaluation of the anatomical and physiological characteristics of swallow. The temporal parameters, however, cannot be studied using this technique. Motion artifacts preclude its use in the study of mastication. It remains complementary to videofluoroscopy and other techniques in swallow evaluation. PMID:14571329

Hartl, Dana M; Albiter, Marcella; Kolb, Frédéric; Luboinski, Bernard; Sigal, Robert

2003-01-01

421

Transverse single-spin asymmetries of pion production in semi-inclusive DIS at subleading twist  

NASA Astrophysics Data System (ADS)

We study the single-spin asymmetries with the sin?S and sin(2?h-?S) angular dependences for charged and neutral pions produced in semi-inclusive deep inelastic scattering on the transversely polarized proton target. The theoretical interpretations of the two asymmetries are presented in terms of the convolution of the twist-3 quark transverse momentum dependent distributions and twist-2 fragmentation functions. Specifically, we investigate the role of the distributions fT, hT, and hT? in the sin?S asymmetry, as well as the role of the distributions fT?, hT, and hT? in the sin(2?h-?S) asymmetry. We calculate these distributions in a spectator-diquark model and predict the corresponding asymmetries for the first time, considering the kinematics at HERMES, JLab, and COMPASS. The numerical estimates show that the asymmetries are sizable, and the dominant contribution to the sin?S asymmetry comes from the T-odd distribution fT, while fT? gives the main contribution to the sin(2?h-?S) asymmetry. The future measurements on these asymmetries can shed light on the information of twist-3 transverse momentum dependent distributions.

Mao, Wenjuan; Lu, Zhun; Ma, Bo-Qiang

2014-07-01

422

Single transverse spin asymmetry of dilepton production near Z0 pole  

NASA Astrophysics Data System (ADS)

Using the latest quark Sivers functions extracted from the global analysis of available data on single transverse spin asymmetry (SSA), we calculate the SSA of Drell-Yan inclusive production of lepton pairs of invariant mass Q at both 4

Kang, Zhong-Bo; Qiu, Jian-Wei

2010-03-01

423

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

SciTech Connect

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

Guo, Junji; Liao, Wenhu, E-mail: whliao2007@aliyun.com; Zhao, Heping [College of Physics, Mechanical and Electrical Engineering, Jishou University, Jishou 416000 (China); Zhou, Guanghui [Department of Physics and Key Laboratory for Low-Dimensional Quantum Structures and Manipulation (Ministry of Education), Hunan Normal University, Changsha 410081 (China)

2014-01-14

424

Controlled transport of superparamagnetic beads with spin-valves  

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

425

Entanglement entropy and fidelity susceptibility in the one-dimensional spin-1 XXZ chains with alternating single-site anisotropy  

NASA Astrophysics Data System (ADS)

We study the fidelity susceptibility in an antiferromagnetic spin-1 XXZ chain numerically. By using the density-matrix renormalization group method, the effects of the alternating single-site anisotropy D on fidelity susceptibility are investigated. Its relation with the quantum phase transition is analyzed. It is found that the quantum phase transition from the Haldane spin liquid to periodic Néel spin solid can be well characterized by the fidelity. Finite size scaling of fidelity susceptibility shows a power-law divergence at criticality, which indicates the quantum phase transition is of second order. The results are confirmed by the second derivative of the ground-state energy. We also study the relationship between the entanglement entropy, the Schmidt gap and quantum phase transitions. Conclusions drawn from these quantum information observables agree well with each other.

Ren, Jie; Liu, Guang-Hua; You, Wen-Long

2015-03-01

426

Superconductivity on a Crossover Phenomenon of Spin–Ladder System SrCa13Cu24O41 Single Crystals  

NASA Astrophysics Data System (ADS)

Electrical resistivity and alternating current susceptibility measurements were performed for the spin–ladder compound SrCa13Cu24O41 under hydrostatic pressure up to 8 GPa. The superconducting transition was observed below TC = 14.7 K at pressures above 2 GPa. By using high-quality single crystals, the bulk superconductivity with a volume fraction of 50% and temperature quadratic behavior of the normal state resistivity were observed above 3.7 GPa. They suggest that a strong interladder interaction induces the bulk superconductivity and transforms the system into a Fermi-liquid-like state. The optimal pressure was in a crossover region and the highest TC was observed without going through the bulk superconducting state. Our results suggest that the superconducting state on the crossover phenomenon presents the feature of the doped two-leg spin–ladder system because the spin gap was observed in this compound.

Hisada, Akihiko; Matsubayashi, Kazuyuki; Uwatoko, Yoshiya; Fujiwara, Naoki; Deng, Guochu; Pomjakushina, Ekaterina; Conder, Kazimierz; Mohan Radheep, Dinadhayalane; Thiyagarajan, Raman; Esakkimuthu, Sankaran; Arumugam, Sonachalam

2014-07-01

427

Entanglement entropy and fidelity susceptibility in the one-dimensional spin-1 XXZ chains with alternating single-site anisotropy  

E-print Network

We study the fidelity susceptibility in an antiferromagnetic spin-1 XXZ chain numerically. By using the density-matrix renormalization group method, the effects of the alternating single-site anisotropy $D$ on fidelity susceptibility are investigated. Its relation with the quantum phase transition is analyzed. It is found that the quantum phase transition from the Haldane spin liquid to periodic N\\'{e}el spin solid can be well characterized by the fidelity. Finite size scaling of fidelity susceptibility shows a power-law divergence at criticality, which indicates the quantum phase transition is of second order. The results are confirmed by the second derivative of the ground-state energy. We also study the relationship between the entanglement entropy, the Schmidt gap and quantum phase transitions. Conclusions drawn from these quantum information observables agree well with each other.

Jie Ren; Guang-Hua Liu; Wen-Long You

2015-02-18

428

Entanglement entropy and fidelity susceptibility in the one-dimensional spin-1 XXZ chains with alternating single-site anisotropy.  

PubMed

We study the fidelity susceptibility in an antiferromagnetic spin-1 XXZ chain numerically. By using the density-matrix renormalization group method, the effects of the alternating single-site anisotropy D on fidelity susceptibility are investigated. Its relation with the quantum phase transition is analyzed. It is found that the quantum phase transition from the Haldane spin liquid to periodic Néel spin solid can be well characterized by the fidelity. Finite size scaling of fidelity susceptibility shows a power-law divergence at criticality, which indicates the quantum phase transition is of second order. The results are confirmed by the second derivative of the ground-state energy. We also study the relationship between the entanglement entropy, the Schmidt gap and quantum phase transitions. Conclusions drawn from these quantum information observables agree well with each other. PMID:25707024

Ren, Jie; Liu, Guang-Hua; You, Wen-Long

2015-03-18

429

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

NASA Astrophysics Data System (ADS)

Photon-echo based optical quantum memory schemes often employ intermediate steps to transform optical coherences to spin coherences for longer storage times. We analyze a scheme that uses three identical chirped control pulses for coherence rephasing in an inhomogeneously broadened ensemble of three-level ? systems. The pulses induce a cyclic permutation of the atomic populations in the adiabatic regime. Optical coherences created by a s