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1

Aharonov-Bohm Radiation  

E-print Network

A solenoid oscillating in vacuum will pair produce charged particles due to the Aharonov-Bohm (AB) interaction. We calculate the radiation pattern and power emitted for charged scalar particles. We extend the solenoid analysis to cosmic strings, and find enhanced radiation from cusps and kinks on loops. We argue by analogy with the electromagnetic AB interaction that cosmic strings should emit photons due to the gravitational AB interaction of fields in the conical spacetime of a cosmic string. We calculate the emission from a kink and find that it is of similar order as emission from a cusp, but kinks are vastly more numerous than cusps and may provide a more interesting observational signature.

Katherine Jones-Smith; Harsh Mathur; Tanmay Vachaspati

2009-11-03

2

Tunable exciton Aharonov-Bohm effect in a quantum ring  

NASA Astrophysics Data System (ADS)

We studied the optical Aharonov-Bohm effect for an exciton in a semiconductor quantum ring. A perpendicular electric field applied to a quantum ring with large height, is able to tune the exciton ground state energy such that it exhibits a weak observable Aharonov-Bohm oscillations. This Aharonov-Bohm effect is tunable in strength and period.

Li, Bin; Magnus, W.; Peeters, F. M.

2010-02-01

3

Tunable exciton Aharonov-Bohm effect in a quantum ring  

Microsoft Academic Search

We studied the optical Aharonov-Bohm effect for an exciton in a semiconductor quantum ring. A perpendicular electric field applied to a quantum ring with large height, is able to tune the exciton ground state energy such that it exhibits a weak observable Aharonov-Bohm oscillations. This Aharonov-Bohm effect is tunable in strength and period.

Bin Li; W. Magnus; F. M. Peeters

2010-01-01

4

Optical theorem for Aharonov-Bohm scattering  

Microsoft Academic Search

Quantum-mechanical scattering off a magnetic vortex is considered, and the optical theorem is derived. The vortex core is assumed to be impermeable to scattered particles, and its transverse size is taken into account. We show that the scattering Aharonov-Bohm effect is independent of the choice of boundary conditions from the variety of the Robin ones. The behaviour of the scattering

Yu A. Sitenko; N. D. Vlasii

2011-01-01

5

The optical Aharonov-Bohm effect  

Microsoft Academic Search

It is shown that the vector potential of a circularly polarized laser causes the optical equivalent of the Aharonov-Bohm effect. An estimate is made of the expected fringe shift due to a circularly polarized laser directed through an optical fiber in an electron diffraction experiment, and it is shown that the effect is equivalent to that of a magnetic field.

M. W. Evans

1994-01-01

6

The Electric Aharonov-Bohm Effect  

E-print Network

In their seminal paper Aharonov and Bohm (1959) claimed that electromagnetic fields can act at a distance on charged particles even if they are identically zero in the region of space where the particles propagate. They proposed two experiments to verify their theoretical conclusions. The magnetic effect, that has been extensively studied, and the electric effect where an electron is affected by a time-dependent electric potential that is constant in the region where the electron is propagating, i.e., such that the electric field vanishes along its trajectory. The Aharonov-Bohm effects imply such a strong departure from the physical intuition coming from classical physics that it is no wonder that they remain a highly controversial issue, after more than fifty years. The existence of electric Aharonov-Bohm effect, that has not been confirmed experimentally, is a very controversial issue. In their 1959 paper Aharonov and Bohm proposed an Ansatz for the solution to the Schroedinger equation in regions where there is a time-dependent electric potential that is constant in space. It consists in multiplying the free evolution by a phase given by the integral in time of the potential. The validity of this Ansatz predicts interference fringes between parts of a coherent electron beam that are subjected to different potentials. In this paper we prove that the exact solution to the Schroedinger equation is given by the Aharonov-Bohm Ansatz up to an error bound in norm that is uniform in time and that decays as a constant divided by the velocity. Our results give, for the first time, a rigorous proof that quantum mechanics predicts the existence of the electric Aharonov-Bohm effect, under conditions that we provide. We hope that our results will estimulate the experimental research on the electric Aharonov-Bohm effect.

Ricardo Weder

2010-06-07

7

The Aharonov-Bohm effect revisited  

Microsoft Academic Search

Schrodinger's equation for an electron in a vector potential A has a one-to-one correspondence with the wave equation for an electric field in a moving medium. First the author points out a few errors in the literature concerning the Aharonov-Bohm (AB) effect then she explores the optical analogy further. The author finds that curl A plays a similar role to

H. Fearn

1995-01-01

8

Optical theorem and Aharonov-Bohm scattering  

Microsoft Academic Search

A rigorous derivation of the optical theorem (OT) from the conservation of probability flux (CPF) is presented for scattering\\u000a on an arbitrary spherically symmetric potential inN-spatial dimensions (ND). The constructed expression for the OT is found to yield the corresponding well-known results for\\u000a two- and three-dimensional cases in a rather natural way. The Aharonov-Bohm (AB) effect is considered as a

M. M. Panja; P K Bera; B. Talukdar

1995-01-01

9

Optical Aharonov-Bohm effect: an inverse hyperbolic problems approach  

E-print Network

We describe the general setting for the optical Aharonov-Bohm effect based on the inverse problem of the identification of the coefficients of the governing hyperbolic equation by the boundary measrements. We interpret the inverse problem result as a possibility in principle to detect the optical Aharonov-Bohm effect by the boundary measurements.

Eskin, Gregory

2007-01-01

10

Photonic Aharonov-Bohm Effect Based on Dynamic Modulation  

NASA Astrophysics Data System (ADS)

We show that when the refractive index of a photonic system is harmonically modulated, the phase of the modulation introduces an effective gauge potential for photons. This effective gauge potential can be used to create a photonic Aharonov-Bohm effect. We show that the photonic Aharonov-Bohm effect provides the optimal mechanism for achieving complete on-chip nonmagnetic optical isolation.

Fang, Kejie; Yu, Zongfu; Fan, Shanhui

2012-04-01

11

Optical Aharonov-Bohm Effect: An Inverse Hyperbolic Problems Approach  

NASA Astrophysics Data System (ADS)

We describe the general setting for the optical Aharonov-Bohm effect based on the inverse problem of the identification of the coefficients of the governing hyperbolic equation by the boundary measurements. We interpret the inverse problem result as a possibility in principle to detect the optical Aharonov-Bohm effect by the boundary measurements.

Eskin, G.

2008-12-01

12

Optical Aharonov-Bohm Effect: An Inverse Hyperbolic Problems Approach  

Microsoft Academic Search

We describe the general setting for the optical Aharonov-Bohm effect based on the inverse problem of the identification of\\u000a the coefficients of the governing hyperbolic equation by the boundary measurements. We interpret the inverse problem result\\u000a as a possibility in principle to detect the optical Aharonov-Bohm effect by the boundary measurements.

Gregory Eskin

2008-01-01

13

Optical Aharonov-Bohm effect: an inverse hyperbolic problems approach  

E-print Network

We describe the general setting for the optical Aharonov-Bohm effect based on the inverse problem of the identification of the coefficients of the governing hyperbolic equation by the boundary measurements. We interpret the inverse problem result as a possibility in principle to detect the optical Aharonov-Bohm effect by the boundary measurements.

Gregory Eskin

2007-07-19

14

Photonic Aharonov-Bohm effect in photon-phonon interactions  

NASA Astrophysics Data System (ADS)

The Aharonov-Bohm effect is one of the most intriguing phenomena in both classical and quantum physics, and associates with a number of important and fundamental issues in quantum mechanics. The Aharonov-Bohm effects of charged particles have been experimentally demonstrated and found applications in various fields. Recently, attention has also focused on the Aharonov-Bohm effect for neutral particles, such as photons. Here we propose to utilize the photon-phonon interactions to demonstrate that photonic Aharonov-Bohm effects do exist for photons. By introducing nonreciprocal phases for photons, we observe experimentally a gauge potential for photons in the visible range based on the photon-phonon interactions in acousto-optic crystals, and demonstrate the photonic Aharonov-Bohm effect. The results presented here point to new possibilities to control and manipulate photons by designing an effective gauge potential.

Li, Enbang; Eggleton, Benjamin J.; Fang, Kejie; Fan, Shanhui

2014-01-01

15

Photonic Aharonov-Bohm effect in photon-phonon interactions.  

PubMed

The Aharonov-Bohm effect is one of the most intriguing phenomena in both classical and quantum physics, and associates with a number of important and fundamental issues in quantum mechanics. The Aharonov-Bohm effects of charged particles have been experimentally demonstrated and found applications in various fields. Recently, attention has also focused on the Aharonov-Bohm effect for neutral particles, such as photons. Here we propose to utilize the photon-phonon interactions to demonstrate that photonic Aharonov-Bohm effects do exist for photons. By introducing nonreciprocal phases for photons, we observe experimentally a gauge potential for photons in the visible range based on the photon-phonon interactions in acousto-optic crystals, and demonstrate the photonic Aharonov-Bohm effect. The results presented here point to new possibilities to control and manipulate photons by designing an effective gauge potential. PMID:24476790

Li, Enbang; Eggleton, Benjamin J; Fang, Kejie; Fan, Shanhui

2014-01-01

16

Photonic Aharonov-Bohm effect in photon-phonon interactions  

PubMed Central

The Aharonov–Bohm effect is one of the most intriguing phenomena in both classical and quantum physics, and associates with a number of important and fundamental issues in quantum mechanics. The Aharonov–Bohm effects of charged particles have been experimentally demonstrated and found applications in various fields. Recently, attention has also focused on the Aharonov–Bohm effect for neutral particles, such as photons. Here we propose to utilize the photon–phonon interactions to demonstrate that photonic Aharonov–Bohm effects do exist for photons. By introducing nonreciprocal phases for photons, we observe experimentally a gauge potential for photons in the visible range based on the photon–phonon interactions in acousto-optic crystals, and demonstrate the photonic Aharonov–Bohm effect. The results presented here point to new possibilities to control and manipulate photons by designing an effective gauge potential. PMID:24476790

Li, Enbang; Eggleton, Benjamin J.; Fang, Kejie; Fan, Shanhui

2014-01-01

17

Optical theorem for Aharonov-Bohm scattering  

NASA Astrophysics Data System (ADS)

Quantum-mechanical scattering off a magnetic vortex is considered, and the optical theorem is derived. The vortex core is assumed to be impermeable to scattered particles, and its transverse size is taken into account. We show that the scattering Aharonov-Bohm effect is independent of the choice of boundary conditions from the variety of the Robin ones. The behaviour of the scattering amplitude in the forward direction is analysed, and the persistence of the Fraunhofer diffraction in the short-wavelength limit is shown to be crucial for maintaining the optical theorem in the quasiclassical limit.

Sitenko, Yu A.; Vlasii, N. D.

2011-08-01

18

Deflating the Aharonov-Bohm Effect  

E-print Network

I argue that the metaphysical import of the Aharonov-Bohm effect has been overstated: correctly understood, it does not require either rejection of gauge invariance or any novel form of nonlocality. The conclusion that it does require one or the other follows from a failure to keep track, in the analysis, of the complex scalar field to which the magnetic vector potential is coupled. Once this is recognised, the way is clear to a local account of the ontology of electrodynamics (or at least, to an account no more nonlocal than quantum theory in general requires); I sketch a possible such account.

David Wallace

2014-07-18

19

The optical Aharonov-Bohm effect Polarization effects in the opticalPolarization effects in the optical AharonovAharonov--BohmBohm  

E-print Network

The optical Aharonov-Bohm effect Polarization effects in the opticalPolarization effects in the optical AharonovAharonov--BohmBohm oscillations in quantum rings.oscillations in quantum rings. Luis Dias. · A net Aharonov-Bohm phase arises signatures in the optical emission and absorption of the Optical AB

Dias, Luis Gregório

20

The Aharonov–Bohm effect in the momentum space  

Microsoft Academic Search

The Schrödinger formalism of quantum mechanics is used to demonstrate the existence of the Aharonov–Bohm effect in momentum space and set-ups for experimentally demonstrating it are proposed for either free or ballistic electrons.

D. Dragoman; S. Bogdan

2008-01-01

21

Electric Aharonov-Bohm effect and multiple beam atom interference  

Microsoft Academic Search

The field of atom interferometry is experiencing rapid progress. Atom interferometers have been used to determine topological phase shifts such as the Aharonov-Bohm or Aharonov-Casher effects. Both two beam and more recently multiple beam atom interferometers have been realized. We report on an investigation of the electric (or scalar) Aharonov-Bohm effect in a multiple beam Ramsey experiment. The topological phase

M. Weitz; M. Mel; T. W. Hansch

1999-01-01

22

Aharonov-Bohm effects on optical phonons in carbon nanotubes  

Microsoft Academic Search

Effects of electron-phonon interaction on optical phonons are studied in carbon nanotubes. In metallic nanotubes, the gap due to an Aharonov-Bohm magnetic flux oriented in the tube axis causes a singular behavior in the broadening. In particular, the broadening appears in the transverse mode and diverges when the gap reaches the phonon energy. This Aharonov-Bohm effect can be used for

Kohta Ishikawa; Tsuneya Ando

2007-01-01

23

Photonic Aharonov-Bohm effect based on dynamic modulation.  

PubMed

We show that when the refractive index of a photonic system is harmonically modulated, the phase of the modulation introduces an effective gauge potential for photons. This effective gauge potential can be used to create a photonic Aharonov-Bohm effect. We show that the photonic Aharonov-Bohm effect provides the optimal mechanism for achieving complete on-chip nonmagnetic optical isolation. PMID:22587255

Fang, Kejie; Yu, Zongfu; Fan, Shanhui

2012-04-13

24

Aharonov-Bohm effect in optical activity  

NASA Astrophysics Data System (ADS)

Optically active media have the helical and dissymmetric crystal structure, which constrains the motions of the electrons to a helical path under the influence of the incident electric field. The charge flow along the helices induces a magnetic field in the direction of the axis of helices. The helical structure hence acts as natural micro-solenoids for the electromagnetic waves passing through them. Optical rotation is related to the difference in the accumulative Aharonov-Bohm (AB) phase between the right- and the left-circularly polarized waves. The AB phase is proportional to the angular momentum of an electron moving around the micro-solenoid. Originally the AB phase is shown to be a continuous function of the magnetic flux. However, quantization of the geometrical angular momentum leads to the quantized AB phase. The rotatory power and the Verdet constant are proportional to the refractive index of the medium. The quantized current in the micro-solenoid is proportional to the Bohr magneton and inversely proportional to the area of the helices.

Tan, C. Z.

2010-09-01

25

Polarized excitons in nanorings and the optical Aharonov-Bohm effect A. O. Govorov  

E-print Network

Polarized excitons in nanorings and the optical Aharonov-Bohm effect A. O. Govorov Department and the well known Aharonov-Bohm AB effect.4 Such a case appears naturally in systems with ring geometry. A prominent example is the Aharonov-Bohm phase, which has been studied in connection with the conductance

Ludwig-Maximilians-Universität, München

26

Impurity effects on the Aharonov-Bohm optical signatures of neutral quantum-ring magnetoexcitons  

E-print Network

Impurity effects on the Aharonov-Bohm optical signatures of neutral quantum-ring magnetoexcitons L to the long-studied Aharonov-Bohm effect (ABE).1 This effect is specially important if the particle with experimen- tally accessible characteristics. The optical manifestations of such excitonic Aharonov- Bohm

Dias, Luis Gregório

27

Anomalous aharonov-bohm gap oscillations in carbon nanotubes.  

PubMed

The gap oscillations caused by a magnetic flux penetrating a carbon nanotube represent one of the most spectacular observations of the Aharonov-Bohm effect at the nanoscale. Our understanding of this effect is, however, based on the assumption that the electrons are strictly confined on the tube surface, on trajectories that are not modified by curvature effects. Using an ab initio approach based on density functional theory, we show that this assumption fails at the nanoscale inducing important corrections to the physics of the Aharonov-Bohm effect. Curvature effects and electronic density that is spilled out of the nanotube surface are shown to break the periodicity of the gap oscillations. We predict the key phenomenological features of this anomalous Aharonov-Bohm effect in semiconductive and metallic tubes and the existence of a large metallic phase in the low flux regime of multiwalled nanotubes, also suggesting possible experiments to validate our results. PMID:21805987

Sangalli, Davide; Marini, Andrea

2011-10-12

28

Aharonov-Bohm magnetism and Landau diamagnetism in semimetals  

E-print Network

We compute the magnetic response of hollow semimetal cylinders and rings to the presence of an axial Aharonov-Bohm magnetic flux, in the absence of interactions. We predict nullification of the Aharonov-Bohm effect for a class of dispersion laws that includes "non-relativistic" dispersion and demonstrate that at zero flux the ground-state of a very short "armchair" graphene tube will exhibit a ferromagnetic broken symmetry. We also compute the diamagnetic response of bulk semimetals to the presence of a uniform magnetic field, specifically predicting that the susceptibility has a logarithmic dependence on the size of the sample.

Eugene B. Kolomeisky; Joseph P. Straley

2011-12-29

29

Aharonov-Bohm magnetism and Landau diamagnetism in semimetals  

E-print Network

We compute the magnetic response of hollow semimetal cylinders and rings to the presence of an axial Aharonov-Bohm magnetic flux, in the absence of interactions. We predict nullification of the Aharonov-Bohm effect for a class of dispersion laws that includes "non-relativistic" dispersion and demonstrate that at zero flux the ground-state of a very short "armchair" graphene tube will exhibit a ferromagnetic broken symmetry. We also compute the diamagnetic response of bulk semimetals to the presence of a uniform magnetic field, specifically predicting that the susceptibility has a logarithmic dependence on the size of the sample.

Kolomeisky, Eugene B

2011-01-01

30

Fizeau's experiment and the Aharonov-Bohm effect  

Microsoft Academic Search

The electromagnetic wave equations in a moving medium may be approximated by a form similar to that of the Schrödinger equation for a particle in an electromagnetic field, with the velocity v of the medium and the vorticity ?×v playing the roles of the vector potential and magnetic field, re- spectively. A purely classical optical analogue of the Aharonov-Bohm effect

Richard J. Cook; Heidi Fearn; Peter W. Milonni

1995-01-01

31

Aharonov-Bohm and Coulomb Scattering Near the Forward Direction  

Microsoft Academic Search

The exact wave functions that describe scattering of a charged particle by a confined magnetic field (Aharonov-Bohm effect) and by a Coulomb field are analyzed. It is well known that the usual procedure of finding asymptotic forms of these functions which admit a separation into a superposition of an incident plane wave and a circular or spherical scattered wave is

Charles M. Sommerfield; Hisakazu Minakata

2000-01-01

32

Group-theoretical derivation of Aharonov-Bohm phase shifts  

SciTech Connect

The phase shifts of the Aharonov-Bohm effect are generally determined by means of the partial wave decomposition of the underlying Schroedinger equation. It is shown here that they readily emerge from an o(2,1) calculation of the energy levels employing an added harmonic oscillator potential which discretizes the spectrum.

Hagen, C. R. [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627-0171 (United States)] [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627-0171 (United States)

2013-02-15

33

Spectral and scattering theory for the Aharonov-Bohm operators  

E-print Network

We review the spectral and the scattering theory for the Aharonov-Bohm model on R^2. New formulae for the wave operators and for the scattering operator are presented. The asymptotics at high and at low energy of the scattering operator are computed.

K. Pankrashkin; S. Richard

2009-11-24

34

The Aharonov–Bohm effect in scattering theory  

SciTech Connect

The Aharonov–Bohm effect is considered as a scattering event with nonrelativistic charged particles of the wavelength which is less than the transverse size of an impenetrable magnetic vortex. The quasiclassical WKB method is shown to be efficient in solving this scattering problem. We find that the scattering cross section consists of two terms, one describing the classical phenomenon of elastic reflection and another one describing the quantum phenomenon of diffraction; the Aharonov–Bohm effect is manifested as a fringe shift in the diffraction pattern. Both the classical and the quantum phenomena are independent of the choice of a boundary condition at the vortex edge, providing that probability is conserved. We show that a propagation of charged particles can be controlled by altering the flux of a magnetic vortex placed on their way. -- Highlights: •Aharonov–Bohm effect as a scattering event. •Impenetrable magnetic vortex of nonzero transverse size. •Scattering cross section is independent of a self-adjoint extension employed. •Classical phenomenon of elastic reflection and quantum phenomenon of diffraction. •Aharonov–Bohm effect as a fringe shift in the diffraction pattern.

Sitenko, Yu.A., E-mail: yusitenko@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, National Academy of Sciences, 14-b Metrologichna Str., Kyiv, 03680 (Ukraine); Vlasii, N.D. [Physics Department, Taras Shevchenko National University of Kyiv, 64 Volodymyrska str., Kyiv, 01601 (Ukraine)] [Physics Department, Taras Shevchenko National University of Kyiv, 64 Volodymyrska str., Kyiv, 01601 (Ukraine)

2013-12-15

35

Non-traditional Aharonov-Bohm effects in condensed matter  

SciTech Connect

In 1959, Aharonov and Bohm proposed an elegant experiment demonstrating observability of electromagnetic potentials (or, which is the same, the non-locality of the wave function of charged particles) in quantum mechanics. This paper discusses the Aharonov-Bohm effect, based on the fundamental principles of quantum theory, as the superposition principles, the quantum character of motion of particles and locality of the interaction of a charge with an electromagnetic potential L{sub int} = j{sub {mu}}A{sup {mu}}. It is thus no wonder that the Aharonov-Bohm's paper aroused much dispute which is still ongoing. Originally, the Aharonov-Bohm effect (ABE) means the dependence of the interference pattern on the magnetic fluid flux {phi} in a Gendaken experiment on a coherent electron beam in the field of an infinitely thin solenoid. Later, however, it became common to refer to the Aharonov-Bohm phenomenon wherever the characteristics of systems under study appear to depend on the flux {phi} in the absence of electric and magnetic fields. In this sense, it was highly interesting to analyze the ABE in condensed media (the many-particle Aharonov-Bohm effect), in particular to study the dependence of the thermodynamic and kinetic characteristics, e.g., of metal on the flux. Such a problem was first discussed by Byers and Yang who formulated the general theorems related to the ABE in conducting condensed media. The next important step was the work of Kulik who formulated a concrete model and calculated the flux-dependent contribution to the metal free energy and provided a first clear formulation of the requirements to reveal.

Krive, I.V. (Physical-Technical Dept., Kharkov State Univ., 4 Dzerzhinsky Square, 310077 Kharkov (UA)); Rozhavsky, A.S. (Inst. for Low Temperature and Engineering, Ukrainian Academy of Sciences, 47 Lenin Avenue, 310164 Kharkov (UA))

1992-05-10

36

Kirchhoff diffraction optics and the nascent Aharonov–Bohm effect: a theorem  

Microsoft Academic Search

Textbook diffraction optics, Kirchhoff diffraction, is connected to the Aharonov–Bohm effect of quantum mechanics by an easy theorem proved here. The connection is between the Kirchhoff wave field and the Aharonov–Bohm quantum wave field in the limit of zero flux: the ‘nascent’ Aharonov–Bohm effect. The diffracting opaque screen of Kirchhoff optics is replaced in the quantum mechanics by a magnetic

J H Hannay

2010-01-01

37

Kirchhoff diffraction optics and the nascent Aharonov-Bohm effect: a theorem  

Microsoft Academic Search

Textbook diffraction optics, Kirchhoff diffraction, is connected to the Aharonov-Bohm effect of quantum mechanics by an easy theorem proved here. The connection is between the Kirchhoff wave field and the Aharonov-Bohm quantum wave field in the limit of zero flux: the 'nascent' Aharonov-Bohm effect. The diffracting opaque screen of Kirchhoff optics is replaced in the quantum mechanics by a magnetic

J. H. Hannay

2010-01-01

38

Diffraction and Quasiclassical Limit of the Aharonov--Bohm Effect  

E-print Network

Since the Aharonov-Bohm effect is the purely quantum effect that has no analogues in classical physics, its persistence in the quasiclassical limit seems to be hardly possible. Nevertheless, we show that the scattering Aharonov-Bohm effect does persist in the quasiclassical limit owing to the diffraction, i.e. the Fraunhofer diffraction in the case when space outside the enclosed magnetic flux is Euclidean, and the Fresnel diffraction in the case when the outer space is conical. Hence, the enclosed magnetic flux can serve as a gate for the propagation of short-wavelength, almost classical, particles. In the case of conical space, this quasiclassical effect which is in principle detectable depends on the particle spin.

Sitenko, Yu A

2010-01-01

39

Nonlinear Aharonov-Bohm Scattering by Optical Vortices  

Microsoft Academic Search

We study linear and nonlinear wave scattering by an optical vortex in a self-defocusing nonlinear Kerr medium. In the linear case, we find a splitting of a plane-wave front at the vortex proportional to its circulation, similar to what occurs in the scattered wave of electrons for the Aharonov-Bohm effect. For larger wave amplitudes, we study analytically and numerically the

Dragomir Neshev; Alexander Nepomnyashchy; Yuri S. Kivshar

2001-01-01

40

Optical evidence for Aharonov Bohm effect in quantum tubes  

NASA Astrophysics Data System (ADS)

We present an optical evidence for Aharonov-Bohm (AB) effect in InAs quantum tubes fabricated by a selective area-metal organic vapor phase epitaxy. The oscillations of the photoluminescence peak energies are observed in quantum tubes depending on the magnetic flux through the tube. These oscillations in energies are shown to be due to the AB effect of a charged exciton in a quantum tube by a theory based on the effective-mass approximation.

Nomura, S.; Tsumura, K.; Mohan, P.; Motohisa, J.; Fukui, T.

2008-03-01

41

Observation of Aharonov-Bohm Effect by Electron Holography  

Microsoft Academic Search

In this experiment, an electron- and optical-holographic technique is employed with small toroidal ferromagnets each forming a magnetic-flux closure. The holographic interferometry proves that a phase difference between two electron beams having passed through the field-free regions agrees well with the fundamental relation known as the Aharonov-Bohm effect. It is also confirmed from the same hologram that flux leakage from

Akira Tonomura; Tsuyoshi Matsuda; Ryo Suzuki; Akira Fukuhara; Nobuyuki Osakabe; Hiroshi Umezaki; Junji Endo; Kohsei Shinagawa; Yutaka Sugita; Hideo Fujiwara

1982-01-01

42

Optical evidence for Aharonov–Bohm effect in quantum tubes  

Microsoft Academic Search

We present an optical evidence for Aharonov–Bohm (AB) effect in InAs quantum tubes fabricated by a selective area-metal organic vapor phase epitaxy. The oscillations of the photoluminescence peak energies are observed in quantum tubes depending on the magnetic flux through the tube. These oscillations in energies are shown to be due to the AB effect of a charged exciton in

S. Nomura; K. Tsumura; P. Mohan; J. Motohisa; T. Fukui

2008-01-01

43

The Aharonov-Bohm wave and the Cornu spiral  

Microsoft Academic Search

For flux , the Aharonov-Bohm wavefunction9AB.r;\\/ is represented exactly in terms of Fresnel integrals. Numerical evidence shows that in the complex9AB plane the wave clings to the Cornu spiral for all positionsr except very close to the flux line, that is, the argument w.r;\\/ of the Fresnel integrals is almost real. This is confirmed by deriving an asymptotic expansion for

M V Berry; A Shelankov

1999-01-01

44

Optical exciton Aharonov-Bohm effect, persistent current, and magnetization in semiconductor nanorings of type I and II  

E-print Network

Optical exciton Aharonov-Bohm effect, persistent current, and magnetization in semiconductor of the nanoring)10�15 have demonstrated that the optical exciton Aharonov-Bohm effect (X-ABE), i. e-Universit�at zu Berlin, Newtonstr. 15, 12489 Berlin, Germany (Dated: May 11, 2006) The optical exciton Aharonov-Bohm

Zimmermann, Roland

45

Polarization and Aharonov-Bohm oscillations in quantum-ring magnetoexcitons Luis G. G. V. Dias da Silva,1,  

E-print Network

. INTRODUCTION The manifestation of the optical Aharonov-Bohm1 AB effect in neutral and charged excitonsPolarization and Aharonov-Bohm oscillations in quantum-ring magnetoexcitons Luis G. G. V. Dias da's dipole moment, as well as the interaction screening, play important roles in the Aharonov-Bohm AB

Dias, Luis Gregório

46

pss header will be provided by the publisher Exciton Aharonov-Bohm effect and emission kinetics in nanor-  

E-print Network

Aharonov-Bohm effect (X-ABE), i. e. an oscillatory component in the energy of the optically active (brightpss header will be provided by the publisher Exciton Aharonov-Bohm effect and emission kinetics June 2006 Published online 22 June 2006 PACS 71.35.Ji, 78.67.Hc, 71.35.Cc The Aharonov-Bohm effect

Zimmermann, Roland

47

Experimental demonstration of a photonic Aharonov-Bohm effect at radio frequencies  

NASA Astrophysics Data System (ADS)

Building upon recent theoretical proposals for creating an effective gauge field for photons, we experimentally demonstrate the photonic Aharonov-Bohm effect. The effect relies on the nonreciprocal phase acquired by photons during photonic transitions. Our photonic Aharonov-Bohm interferometer is broadly tunable with a contrast ratio above 30 dB, as the operating frequency varies between 8 and 12 MHz.

Fang, Kejie; Yu, Zongfu; Fan, Shanhui

2013-02-01

48

Spectroscopic peculiarities in a 2D Coulomb potential under Aharonov-Bohm effect  

NASA Astrophysics Data System (ADS)

In this paper we demonstrate some spectroscopic peculiarities which occur in the presence of the Aharonov-Bohm effect. As an object of investigation the system of a two-dimensional (2D) Coulomb potential in the presence of the Aharonov-Bohm flux is considered. It is shown, that the bound states in such a system “feel” the presence of the magnetic flux. In particular, the numerical analysis shows that the oscillator strengths of optical transitions turn into zero at some “special” values of the Aharonov-Bohm flux. As a result, some spectral lines (namely, the intensities of spectral lines) will disappear and this fact may be considered as an observable optical manifestation of the Aharonov-Bohm effect in the considered system. The dynamic polarisability of the bound states of an electron in such a system is also analyzed. It is shown numerically that the dynamic polarisability “strongly” depends on the values of the Aharonov-Bohm flux.

Meleshenko, Peter A.; Nguyen, Hang T. T.; Klinskikh, Alexander F.

2013-10-01

49

Gravitational Aharonov-Bohm effect and gravitational lensing  

E-print Network

Considering the spacetime around a rotating massif body it is seen that the time of flight of a light ray is different whether it travels on one side of the source or on the other. The difference is proportional to the angular momentum of the body. In the case that a compact rapidly rotating object is the source of a gravitational lensing effect, the contribution coming from the above mentioned gravitational Aharonov-Bohm effect should be added to the other causes of phase difference between light rays coming from different images of the same object.

A. Tartaglia

2000-03-08

50

Aharonov-Bohm effect without closing a loop  

SciTech Connect

We discuss the consequences of the Aharonov-Bohm (AB) effect in setups involving several charged particles, wherein none of the charged particles encloses a closed loop around the magnetic flux. We show that in such setups, the AB phase is encoded either in the relative phase of a bipartite or multipartite entangled photons states, or alternatively, gives rise to an overall AB phase that can be measured relative to another reference system. These setups involve processes of annihilation or creation of electron-hole pairs. We discuss the relevance of such effects in 'vacuum birefringence' in QED, and comment on their connection to other known effects.

Retzker, A.; Nussinov, S.; Reznik, B. [Department of Physics and Astronomy, Tel-Aviv University, Tel Aviv 69978 (Israel); Aharonov, Y. [Department of Physics and Astronomy, Tel-Aviv University, Tel Aviv 69978 (Israel); Department of Physics, University of South Carolina, Columbia (United States); Botero, A. [Department of Physics, University of South Carolina, Columbia (United States); Departamento de Fisica, Universidad de Los Andes, Apartado Aereo 4976, Bogota (Colombia)

2006-03-15

51

Inelastic transport through Aharonov-Bohm interferometer in Kondo regime  

SciTech Connect

We formulate elastic and inelastic parts of linear conductance through an Aharonov-Bohm (AB) ring with an embedded quantum dot in the Kondo regime. The inelastic part G{sub inel} is proportional to T{sup 2} when the temperature T is much smaller than the Kondo temperature T{sub K}, whereas it is negligibly small compared with elastic part G{sub el} when T ? T{sub K}. G{sub inel} weakly depends on the magnetic flux penetrating the AB ring, which disturbs the precise detection of G{sub el}/(G{sub el}+G{sub inel}) by the visibility of AB oscillation.

Yoshii, Ryosuke; Eto, Mikio [Faculty of Science and Technology, Keio University, Yokohama 223-8522 (Japan); Sakano, Rui [Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581 (Japan); Affleck, Ian [Department of Physics and Astronomy, University of British Columbia, Vancouver (Canada)

2013-12-04

52

Combined Electric and Magnetic Aharonov-Bohm Effects  

E-print Network

It is well-known that the electric and magnetic Aharonov-Bohm effects may be formally described on equal footing using the four-vector potential in a relativistic framework. We propose an illustrative manifestation of both effects in a single configuration, in which the specific path of the charged particle determines the weight of the electric and magnetic acquired relative phases. The phases can be distinctively obtained in the Coulomb gauge. The scheme manifests the pedagogical lesson that though each of the relative phases is gauge-dependent their sum is gauge-invariant.

Samuel Marcovitch; Yakir Aharonov; Tirza Kaufferr; Benni Reznik

2007-09-11

53

Aharonov-Bohm and Coulomb Scattering Near the Forward Direction  

E-print Network

The exact wave functions that describe scattering of a charged particle by a confined magnetic field (Aharonov-Bohm effect) and by a Coulomb field are analyzed. It is well known that the usual procedure of finding asymptotic forms of these functions which admit a separation into a superposition of an incident plane wave and a circular or spherical scattered wave is problematic near the forward direction. It thus appears to be impossible to express the conservation of probability by means of an optical theorem of the usual kind. Both the total cross section and the forward scattering amplitude appear to be infinite. To address these difficulties we find a new representation for the asymptotic form of the Aharonov-Bohm wave function that is valid for all angles. Rather than try to define a cross section at forward angles, however, we work instead with the probability current and find that it is quite well behaved. The same is true for Coulomb scattering. We trace the usual difficulties to a nonuniformity of lim...

Sommerfield, C M; Sommerfield, Charles M.; Minakata, Hisakazu

2000-01-01

54

Kirchhoff diffraction optics and the nascent Aharonov-Bohm effect: a theorem  

NASA Astrophysics Data System (ADS)

Textbook diffraction optics, Kirchhoff diffraction, is connected to the Aharonov-Bohm effect of quantum mechanics by an easy theorem proved here. The connection is between the Kirchhoff wave field and the Aharonov-Bohm quantum wave field in the limit of zero flux: the 'nascent' Aharonov-Bohm effect. The diffracting opaque screen of Kirchhoff optics is replaced in the quantum mechanics by a magnetic flux line, or loop, in the shape of the boundary edge of the screen. The gauge must be chosen appropriately: a delta function on that surface, spanning the boundary edge, which matches the screen.

Hannay, J. H.

2010-09-01

55

Magneto-optical spectra of carbon nanotubes: effect of Aharonov–Bohm flux on depolarization effect  

Microsoft Academic Search

Optical absorption spectra of carbon nanotubes in a magnetic field perpendicular to the tube axis, are calculated for parallel polarization. A depolarization field is induced by Aharonov–Bohm flux, which reduces the lowest peak dramatically.

Hiroshi Ajiki

2002-01-01

56

Classical light analogue of the nonlocal Aharonov-Bohm effect  

E-print Network

We demonstrate the existence of a non-local geometric phase in the intensity-intensity correlations of classical incoherent light, that is not seen in the lower order correlations. This two-photon Pancharatnam phase was observed and modulated in a Mach-Zehnder interferometer. Using acousto-optic interaction, independent phase noise was introduced to light in the two arms of the interferometer to create two independent incoherent classical sources from laser light. The experiment is the classical optical analogue of the multi-particle Aharonov-Bohm effect. As the trajectory of light over the Poincare sphere introduces a phase shift observable only in the intensity-intensity correlation, it provides a means of deflecting the two-photon wavefront, while having no effect on single photons.

Satapathy, Nandan; Mehta, Poonam; Sinha, Supurna; Samuel, Joseph; Ramachandran, Hema

2012-01-01

57

Nonlinear Aharonov-Bohm Scattering by Optical Vortices  

SciTech Connect

We study linear and nonlinear wave scattering by an optical vortex in a self-defocusing nonlinear Kerr medium. In the linear case, we find a splitting of a plane-wave front at the vortex proportional to its circulation, similar to what occurs in the scattered wave of electrons for the Aharonov-Bohm effect. For larger wave amplitudes, we study analytically and numerically the scattering of a dark-soliton stripe (a nonlinear analog of a small-amplitude wave packet) by a vortex and observe a significant asymmetry of the scattered wave. Subsequently, a wave-front splitting of the scattered wave develops into transverse modulational instability, ''unzipping'' the stripe into trains of vortices with opposite charges.

Neshev, Dragomir; Nepomnyashchy, Alexander; Kivshar, Yuri S.

2001-07-23

58

Nonlinear Aharonov-Bohm scattering by optical vortices.  

PubMed

We study linear and nonlinear wave scattering by an optical vortex in a self-defocusing nonlinear Kerr medium. In the linear case, we find a splitting of a plane-wave front at the vortex proportional to its circulation, similar to what occurs in the scattered wave of electrons for the Aharonov-Bohm effect. For larger wave amplitudes, we study analytically and numerically the scattering of a dark-soliton stripe (a nonlinear analog of a small-amplitude wave packet) by a vortex and observe a significant asymmetry of the scattered wave. Subsequently, a wave-front splitting of the scattered wave develops into transverse modulational instability, "unzipping" the stripe into trains of vortices with opposite charges. PMID:11461616

Neshev, D; Nepomnyashchy, A; Kivshar, Y S

2001-07-23

59

Fizeau`s experiment and the Aharonov--Bohm effect  

SciTech Connect

The electromagnetic wave equations in a moving medium may be approximated by a form similar to that of the Schroedinger equation for a particle in an electromagnetic field, with the velocity {bold v} of the medium and the vorticity {del}{times}{bold v} playing the roles of the vector potential and magnetic field, re- spectively. A purely classical optical analogue of the Aharonov--Bohm effect follows by consider- ation of the interference pattern produced by two beams, each of which propagates in a region with zero vorticity, but such that the flux of the vorticity through the closed loop defined by the optical paths does not vanish. Fizeau`s experiment (1851) on the velocity of light in moving media may be regarded as an example of such a situation. {copyright} {ital 1995} {ital American} {ital Association} {ital of} {ital Physics} {ital Teachers}.

Cook, R.J. [Department of Physics, United States Air Force Academy, Colorado Springs, Colorado 80840 (United States); Fearn, H.; Milonni, P.W. [Theoretical Division (T-4), Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1995-08-01

60

Noncommutative analogue Aharonov-Bohm effect and superresonance  

NASA Astrophysics Data System (ADS)

We consider the idea of modeling a rotating acoustic black hole by an idealized draining bathtub vortex which is a planar circulating flow phenomenon with a sink at the origin. We find the acoustic metric for this phenomenon from a noncommutative Abelian Higgs model. As such the acoustic metric not only describes a rotating acoustic black hole but also inherits the noncommutative characteristic of the spacetime. We address the issues of superresonance and analogue Aharonov-Bohm (AB) effect in this background. We mainly show that the scattering of planar waves by a draining bathtub vortex leads to a modified AB effect and due to spacetime noncommutativity, the phase shift persists even in the limit where the parameters associated with the circulation and draining vanish. Finally, we also find that the analogue AB effect and superresonance are competing phenomena at a noncommutative spacetime.

Anacleto, M. A.; Brito, F. A.; Passos, E.

2013-06-01

61

Fizeau's experiment and the Aharonov-Bohm effect  

NASA Astrophysics Data System (ADS)

The electromagnetic wave equations in a moving medium may be approximated by a form similar to that of the Schrödinger equation for a particle in an electromagnetic field, with the velocity v of the medium and the vorticity ?×v playing the roles of the vector potential and magnetic field, re- spectively. A purely classical optical analogue of the Aharonov-Bohm effect follows by consider- ation of the interference pattern produced by two beams, each of which propagates in a region with zero vorticity, but such that the flux of the vorticity through the closed loop defined by the optical paths does not vanish. Fizeau's experiment (1851) on the velocity of light in moving media may be regarded as an example of such a situation.

Cook, Richard J.; Fearn, Heidi; Milonni, Peter W.

1995-08-01

62

Magnetic edge states in Aharonov-Bohm graphene quantum rings  

SciTech Connect

The effect of electron-electron interaction on the electronic structure of Aharonov-Bohm (AB) graphene quantum rings (GQRs) is explored theoretically using the single-band tight-binding Hamiltonian and the mean-field Hubbard model. The electronic states and magnetic properties of hexagonal, triangular, and circular GQRs with different sizes and zigzag edge terminations are studied. The results show that, although the AB oscillations in the all types of nanoring are affected by the interaction, the spin splitting in the AB oscillations strongly depends on the geometry and the size of graphene nanorings. We found that the total spin of hexagonal and circular rings is zero and therefore, no spin splitting can be observed in the AB oscillations. However, the non-zero magnetization of the triangular rings breaks the degeneracy between spin-up and spin-down electrons, which produces spin-polarized AB oscillations.

Farghadan, R., E-mail: rfarghadan@kashanu.ac.ir; Heidari Semiromi, E. [Department of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); Saffarzadeh, A. [Department of Physics, Payame Noor University, P.O. Box 19395-3697 Tehran (Iran, Islamic Republic of); Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6 (Canada)

2013-12-07

63

Optical Aharonov-Bohm effect in stacked type-II quantum dots  

Microsoft Academic Search

Excitons in vertically stacked type-II quantum dots (QDs) experience a topological magnetic phase and demonstrate Aharonov-Bohm oscillations in emission intensity. The photoluminescence of vertically stacked ZnTe\\/ZnSe QDs is measured in magnetic fields up to 31T . Aharonov-Bohm oscillations are found in the magnetic-field dependence of the emission intensity. The positions of the peaks of the emission intensity are in good

Igor L. Kuskovsky; W. MacDonald; A. O. Govorov; L. Mourokh; X. Wei; M. C. Tamargo; M. Tadic; F. M. Peeters

2007-01-01

64

Optical Aharonov-Bohm effect in stacked type-II quantum dots  

NASA Astrophysics Data System (ADS)

Excitons in vertically stacked type-II quantum dots (QDs) experience a topological magnetic phase and demonstrate Aharonov-Bohm oscillations in emission intensity. The photoluminescence of vertically stacked ZnTe/ZnSe QDs is measured in magnetic fields up to 31T . Aharonov-Bohm oscillations are found in the magnetic-field dependence of the emission intensity. The positions of the peaks of the emission intensity are in good agreement with numerical simulations of excitons in stacked QDs.

Kuskovsky, Igor L.; MacDonald, W.; Govorov, A. O.; Mourokh, L.; Wei, X.; Tamargo, M. C.; Tadic, M.; Peeters, F. M.

2007-07-01

65

Aharonov-Bohm photonic cages in waveguide and coupled resonator lattices by synthetic magnetic fields.  

PubMed

We suggest a method for trapping photons in quasi-one-dimensional waveguide or coupled-resonator lattices, which is based on an optical analogue of the Aharonov-Bohm cages for charged particles. Light trapping results from a destructive interference of Aharonov-Bohm type induced by a synthetic magnetic field, which is realized by periodic modulation of the waveguide/resonator propagation constants/resonances. PMID:25361112

Longhi, Stefano

2014-10-15

66

Radiation of Supersymmetric Particles from Aharonov-Bohm R-string  

E-print Network

We study radiation of supersymmetric particles from an Aharonov-Bohm string associated with a discrete R-symmetry. Radiation of the lightest supersymmetric particle, when combined with the observed dark matter density, imposes constraints on the string tension or the freeze-out temperature of the particle. We also calculate the amplitude for Aharonov-Bohm radiation of massive spin $3/2$ particles.

Ookouchi, Yutaka

2014-01-01

67

On the Aharonov-Bohm Effect and Why Heisenberg Captures Nonlocality Better Than Schrödinger  

NASA Astrophysics Data System (ADS)

This article is based on my lecture delivered at Tonomura FIRST International Symposium on "Electron Microscopy and Gauge Fields" held in Tokyo on May 9-10, 2012. I discuss in detail the history of the Aharonov-Bohm effect in Bristol and my encounters with Akira Tonomura later on. I then propose an idea that developed following the publication of the Aharonov-Bohm effect, namely the importance of modulo momentum and Heisenberg representation in dealing with non-local quantum phenomena.

Aharonov, Yakir

2014-01-01

68

Aharonov-Bohm Hamiltonians, isospectrality and minimal partitions  

NASA Astrophysics Data System (ADS)

The spectral analysis of Aharonov-Bohm Hamiltonians with flux \\frac12 leads surprisingly to a new insight on some questions of isospectrality appearing for example in Jakobson et al (2006 J. Comput. Appl. Math. 194 141-55) and Levitin et al (J. Phys. A: Math. Gen. 39 2073-82) and of minimal partitions (Helffer et al 2009 Ann. Inst. H. Poincaré Anal. Non Linéaire 26 101-38). We will illustrate this point of view by discussing the question of spectral minimal 3-partitions for the rectangle \\big]{-}\\frac a2,\\frac a2\\big[\\times \\big]{-}\\frac b2,\\frac b2\\big[ , with 0 < a <= b. It has been observed in Helffer et al (2009 Ann. Inst. H. Poincaré Anal. Non Linéaire 26 101-38) that when 0<\\frac ab < \\sqrt{\\vphantom{A^A}\\smash{\\\\frac 38}} the minimal 3-partition is obtained by the three nodal domains of the third eigenfunction corresponding to the three rectangles \\big]{-}\\frac a2,\\frac a2\\big[\\times \\big] {-}\\frac b2,-\\frac b6\\big[, \\big]{-}\\frac a2,\\frac a2\\big[\\times \\big]{-}\\frac b6,\\frac b6\\big[ and \\big]{-}\\frac a2,\\frac a2\\big[\\times \\big] \\frac b6, \\frac b2\\big[ . We will describe a possible mechanism of transition for increasing \\frac ab between these nodal minimal 3-partitions and non-nodal minimal 3-partitions at the value \\sqrt{\\vphantom{A^A}\\smash{\\\\frac 38}} and discuss the existence of symmetric candidates for giving minimal 3-partitions when \\sqrt{\\vphantom{A^A}\\smash{\\\\frac 38}} <\\frac ab \\leq 1 . Numerical analysis leads very naturally to nice questions of isospectrality which are solved by the introduction of Aharonov-Bohm Hamiltonians or by going on the double covering of the punctured rectangle.

Bonnaillie-Noël, V.; Helffer, B.; Hoffmann-Ostenhof, T.

2009-05-01

69

A Gravitational Aharonov-Bohm Effect, and Its Connection to Parametric Oscillators and Gravitational Radiation  

NASA Astrophysics Data System (ADS)

A thought experiment is proposed to demonstrate the existence of a gravitational, vector Aharonov-Bohm effect. We begin the analysis starting from four Maxwell-like equations for weak gravitational fields interacting with slowly moving matter. A connection is made between the gravitational, vector Aharonov-Bohm effect and the principle of local gauge invariance for nonrelativistic quantum matter interacting with weak gravitational fields. The compensating vector fields that are necessitated by this local gauge principle are shown to be incorporated by the DeWitt minimal coupling rule. The nonrelativistic Hamiltonian for weak, time-independent fields interacting with quantum matter is then extended to time-dependent fields, and applied to the problem of the interaction of radiation with macroscopically coherent quantum systems, including the problem of gravitational radiation interacting with superconductors. But first we examine the interaction of EM radiation with superconductors in a parametric oscillator consisting of a superconducting wire placed at the center of a high Q superconducting cavity driven by pump microwaves. Some room-temperature data will be presented demonstrating the splitting of a single microwave cavity resonance into a spectral doublet due to the insertion of a central wire. This would represent an unseparated kind of parametric oscillator, in which the signal and idler waves would occupy the same volume of space. We then propose a separated parametric oscillator experiment, in which the signal and idler waves are generated in two disjoint regions of space, which are separated from each other by means of an impermeable superconducting membrane. We find that the threshold for parametric oscillation for EM microwave generation is much lower for the separated configuration than the unseparated one, which then leads to an observable dynamical Casimir effect. We speculate that a separated parametric oscillator for generating coherent GR microwaves could also be built. [Editor's note: for a video of the talk given by Prof. Chiao at the Aharonov-80 conference in 2012 at Chapman University, see http://quantum.chapman.edu/talk-20.

Chiao, Raymond Y.; Haun, Robert W.; Inan, Nader A.; Kang, Bong-Soo; Martinez, Luis A.; Minter, Stephen J.; Munoz, Gerardo A.; Singleton, Douglas A.

70

Loop Quantum Gravity à la Aharonov-Bohm  

NASA Astrophysics Data System (ADS)

The state space of Loop Quantum Gravity admits a decomposition into orthogonal subspaces associated to diffeomorphism equivalence classes of spin-network graphs. In this paper I investigate the possibility of obtaining this state space from the quantization of a topological field theory with many degrees of freedom. The starting point is a 3-manifold with a network of defect-lines. A locally-flat connection on this manifold can have non-trivial holonomy around non-contractible loops. This is in fact the mathematical origin of the Aharonov-Bohm effect. I quantize this theory using standard field theoretical methods. The functional integral defining the scalar product is shown to reduce to a finite dimensional integral over moduli space. A non-trivial measure given by the Faddeev-Popov determinant is derived. I argue that the scalar product obtained coincides with the one used in Loop Quantum Gravity. I provide an explicit derivation in the case of a single defect-line, corresponding to a single loop in Loop Quantum Gravity. Moreover, I discuss the relation with spin-networks as used in the context of spin foam models.

Bianchi, Eugenio

2014-02-01

71

Two-Particle Nonlocal Aharonov-Bohm Effect from Two Single-Particle Emitters Janine Splettstoesser,1  

E-print Network

Two-Particle Nonlocal Aharonov-Bohm Effect from Two Single-Particle Emitters Janine Splettstoesser at different times. The two-particle correlations manifest themselves as an Aharonov-Bohm effect in noise in optics, the Hanbury Brown­Twiss effect [1] and the Hong-Ou-Mandel effect [2] both result from two

72

Cloaking of matter waves under the global Aharonov-Bohm effect  

SciTech Connect

We discuss the Aharonov-Bohm effect of a magnetic flux for its influence on a two-dimensional quantum cloak. It is shown that the matter wave of a charged particle under the global influence of the Aharonov-Bohm effect can still be perfectly cloaked and guided by the quantum cloak. Since the presence of the global influence of a magnetic flux on charged particles is universal, the perfect cloaking and guiding nature not only provides an ideal setup to cloak an object from matter waves but also provides an ideal setup to test the global physics of charged matter waves in the presence of a bare magnetic flux.

Lin, D.-H. [Department of Physics, National Sun Yat-sen University, Kaohsiung 804, Taiwan (China); Luan, P.-G. [Department of Optics and Photonics, National Central University, Jhongli 320, Taiwan (China)

2009-05-15

73

A Simple Proof of Magnetic and Electric Aharonov-Bohm Effects  

E-print Network

Magnetic Aharonov-Bohm effect (AB effect) was studied in hundreds of papers starting with the seminal paper of Aharonov and Bohm [AB] published in 1959. We give a new proof of the magnetic Aharonov-Bohm effect without using the scattering theory and the theory of inverse boundary value problems. We consider separately the cases of one and several obstacles. The electric AB effect was studied much less. We give the first proof of the electric AB effect in domains with moving boundaries. When the boundary does not move with the time the electric AB effect is absent.

Gregory Eskin

2014-07-20

74

Aharonov-Bohm interferometry with a tunnel-coupled wire  

NASA Astrophysics Data System (ADS)

Recent experiments (Yamamoto et al 2012 Nature Nanotechnology 7 247) used the transport of electrons through an Aharonov-Bohm (AB) interferometer and two coupled channels (at both ends of the interferometer) to demonstrate a manipulable flying qubit. Results included in-phase and anti-phase (AB) oscillations of the two outgoing currents as a function of the magnetic flux, for strong and weak inter-channel coupling, respectively. Here we present new experimental results for a three terminal interferometer, with a tunnel coupling between the two outgoing wires. We show that in some limits, this system is an even simpler realization of the ‘two-slit’ experiment. We also present a simple tight-binding theoretical model which imitates the experimental setup. For weak inter-channel coupling, the AB oscillations in the current which is reflected from the device are very small, and therefore the oscillations in the two outgoing currents must cancel each other, yielding the anti-phase behavior, independent of the length of the coupling regime. Technically, the tight binding equations within the two coupled wires have four solutions for each electronic energy. In the ‘anti-phase’ region all of these solutions are wave-like, oscillating with the distance along the wires. As the coupling between the wires increases, two of these solutions become evanescent, and their amplitudes decay as the electron moves in the wires. In this regime, the amplitudes of the two remaining ‘running’ waves are proportional to each other, with a ratio which is practically flux-independent. As a result, the two outgoing currents are proportional to each other, yielding the ‘in phase’ behavior. For larger coupling all the solutions are evanescent, and the outgoing currents become very small.

Aharony, A.; Takada, S.; Entin-Wohlman, O.; Yamamoto, M.; Tarucha, S.

2014-08-01

75

Aharonov–Bohm effect on exciton absorption of perpendicular light in carbon nanotubes  

Microsoft Academic Search

The Aharonov–Bohm effect on optical absorption of light polarized perpendicularly to the tube axis in semiconducting carbon nanotubes is studied by taking account of exciton and depolarization effect in an effective-mass approximation. The magnetic-flux dependence of the excitation energy is weak and quadratic around zero in contrast to the linear dependence for light polarized parallel to the axis.

Seiji Uryu; Tsuneya Ando

2007-01-01

76

Polarized excitons in nanorings and the optical Aharonov-Bohm effect  

Microsoft Academic Search

The quantum nature of matter lies in the wave function phases that accumulate while particles move along their trajectories. A prominent example is the Aharonov-Bohm phase, which has been studied in connection with the conductance of nanostructures. However, optical response in solids is determined by neutral excitations, for which no sensitivity to magnetic flux would be expected. We propose a

A. O. Govorov; S. E. Ulloa; K. Karrai; R. J. Warburton

2002-01-01

77

Berry's phases in optics: Aharonov-Bohm-like effects and gauge structures in surprising contexts  

Microsoft Academic Search

A general introduction to Berry's phase is given. Connections to twin paradoxes, the Aharonov-Bohm effect and the Dirac monopole, are made. Optical forms of this phase are discussed, with emphasis on an early optical fiber experiment, and a recent interference experiment using a nonplanar Mach-Zehnder interferometer. Connection to quantum measurements is also made.

Raymond Chiao

1989-01-01

78

Plasmonic Aharonov-Bohm effect: Optical spin as the magnetic flux parameter  

Microsoft Academic Search

A wave-front phase dislocation due to the scattering of surface plasmons from a topological defect is directly measured in the near field by means of interference. The dislocation strength is shown to be equal to the incident optical spin with analogy to the magnetic flux parameter in the Aharonov-Bohm effect.

Yuri Gorodetski; Sergey Nechayev; Vladimir Kleiner; Erez Hasman

2010-01-01

79

Aharonov-Bohm effects on bright and dark excitons in carbon nanotubes  

Microsoft Academic Search

A short-range part of the Coulomb interaction causes splitting and shift of excitons due to exchange interaction and mixing between different valleys in semiconducting carbon nanotubes. In the absence of a magnetic flux only a single exciton is optically active (bright) and all others are inactive (dark). Two bright excitons appear in the presence of an Aharonov- Bohm magnetic flux.

Tsuneya Ando

2006-01-01

80

Optical manifestations of the Aharonov-Bohm effect by ion interferometry  

Microsoft Academic Search

The Aharonov-Bohm (AB) effect is manifested in ion interferometry not only by particle or current measurements, but also through spontaneous emission from selected excited states. It is possible, in fact, for the AB phase shift to appear in the optical quantum beat signal but not in the particle counts.

M. P. Silverman

1993-01-01

81

Aharonov-Bohm oscillation and chirality effect in optical activity of single-wall carbon nanotubes  

Microsoft Academic Search

We study the Aharonov-Bohm effect in the optical phenomena of single-wall carbon nanotubes (SWCN) and also their chirality dependence. Especially, we consider the natural optical activity as a proper observable and derive its general expression based on a comprehensive symmetry analysis, which reveals the interplay between the enclosed magnetic flux and the tubule chirality for arbitrary chiral SWCN. A quantitative

Fei Ye; Bing-Shen Wang; Zhao-Bin Su

2004-01-01

82

Aharonov Bohm effect on exciton absorption of perpendicular light in carbon nanotubes  

NASA Astrophysics Data System (ADS)

The Aharonov-Bohm effect on optical absorption of light polarized perpendicularly to the tube axis in semiconducting carbon nanotubes is studied by taking account of exciton and depolarization effect in an effective-mass approximation. The magnetic-flux dependence of the excitation energy is weak and quadratic around zero in contrast to the linear dependence for light polarized parallel to the axis.

Uryu, Seiji; Ando, Tsuneya

2007-12-01

83

PRB/LA13144B Aharonov-Bohm Exciton Absorption Splitting in Chiral Specific  

E-print Network

PRB/LA13144B Aharonov-Bohm Exciton Absorption Splitting in Chiral Specific Single-Walled Carbon-Bohm effect was observed in chiral specific SWNTs by the magneto-absorption measure- ments conducted of the E11 optical excitonic transitions. The parameters of both the dark-bright exciton energy splitting

Maruyama, Shigeo

84

Cross-polarized exciton absorption in carbon nanotubes with Aharonov-Bohm flux  

Microsoft Academic Search

The Aharonov-Bohm effect on optical absorption of light polarized perpendicularly to the tube axis in semiconducting carbon nanotubes is studied by taking account of exciton and depolarization effect within an effective-mass approximation. The excitation energy and oscillator strength exhibit weak and quadratic dependence on the flux around zero in contrast to the linear dependence for light polarized parallel to the

Seiji Uryu; Tsuneya Ando

2007-01-01

85

Plasmonic Aharonov-Bohm effect: Optical spin as the magnetic flux parameter  

NASA Astrophysics Data System (ADS)

A wave-front phase dislocation due to the scattering of surface plasmons from a topological defect is directly measured in the near field by means of interference. The dislocation strength is shown to be equal to the incident optical spin with analogy to the magnetic flux parameter in the Aharonov-Bohm effect.

Gorodetski, Yuri; Nechayev, Sergey; Kleiner, Vladimir; Hasman, Erez

2010-09-01

86

Aharonov-Bohm-type oscillations of thermopower in a quantum-dot ring geometry  

Microsoft Academic Search

We investigate Aharonov-Bohm-type oscillations of the thermopower of a quantum dot embedded in a ring for the case when the interaction between electrons can be neglected. The thermopower is shown to be strongly flux dependent, and typically the amplitude of oscillations exceeds the background value. It is also shown to be essentially dependent on the phase of the scattering matrix,

Ya. M. Blanter; C. Bruder; Rosario Fazio; Herbert Schoeller

1997-01-01

87

The Aharonov-Bohm effect in scattering of short-wavelength particles  

E-print Network

Quantum-mechanical scattering of nonrelativistic charged particles by a magnetic vortex of nonzero transverse size is considered. We show that the flux of the vortex serves as a gate for the strictly forward propagation of particles with short, as compared to the transverse size of the vortex, wavelengths. A possibility for the experimental detection of the scattering Aharonov-Bohm effect is discussed.

Sitenko, Yu A

2011-01-01

88

Optical exciton Aharonov-Bohm effect, persistent current, and magnetization in semiconductor nanorings of type I and II  

Microsoft Academic Search

The optical exciton Aharonov-Bohm effect---i.e., an oscillatory component in the energy of optically active (bright) states---is investigated in nanorings. It is shown that a small effective electron mass, strong confinement of the electron, and high barrier for the hole, achieved, e.g., by an InAs nanoring embedded in an AlGaSb quantum well, are favorable for observing the optical exciton Aharonov-Bohm effect.

M. Grochol; F. Grosse; R. Zimmermann

2006-01-01

89

Optical signatures of the Aharonov-Bohm phase in single-walled carbon nanotubes.  

PubMed

We report interband magneto-optical spectra for single-walled carbon nanotubes in high magnetic fields up to 45 tesla, confirming theoretical predictions that the band structure of a single-walled carbon nanotube is dependent on the magnetic flux phi threading the tube. We have observed field-induced optical anisotropy as well as red shifts and splittings of absorption and photoluminescence peaks. The amounts of shifts and splittings depend on the value of phi/phi(0) and are quantitatively consistent with theories based on the Aharonov-Bohm effect. These results represent evidence of the influence of the Aharonov-Bohm phase on the band gap of a solid. PMID:15155942

Zaric, Sasa; Ostojic, Gordana N; Kono, Junichiro; Shaver, Jonah; Moore, Valerie C; Strano, Michael S; Hauge, Robert H; Smalley, Richard E; Wei, Xing

2004-05-21

90

Optical properties in a two-dimensional quantum ring: Confinement potential and Aharonov-Bohm effect  

NASA Astrophysics Data System (ADS)

Optical properties of a two-dimensional quantum ring with pseudopotential in the presence of an external magnetic field and magnetic flux have been theoretically investigated. Our results show that both of the pseudopotential and magnetic field can affect the third non-linear susceptibility and oscillator strength. In addition, we found that the oscillator strength and the absolute value of the resonant peak of the linear, non-linear and total absorption coefficient demonstrates the Aharonov-Bohm oscillation with magnetic flux, moreover, changes in confinement potential can influence the Aharonov-Bohm oscillation in peak while the resonant peak value of the linear, non-linear and total refractive index changes decreases as magnetic flux increases.

Liang, Shijun; Xie, Wenfang; Shen, Huaya

2011-12-01

91

The Berry phase and the Aharonov-Bohm effect on optical activity.  

PubMed

The helical crystal structure in optically active media acts as the natural micro-solenoids for the electromagnetic waves passing through them, producing the longitudinal magnetic field in the direction of the axis of helices. Magnetic flux through the helical structure is quantized. The Berry phase is induced by rotation of the electrons around the helical structure. Optical rotation is related to the difference in the accumulative Berry phase between the right-, and the left-circularly polarized waves, which is proportional to the magnetic flux through the helical structure, according to the Aharonov-Bohm effect. The optical activity is the natural Faraday effect and the natural Aharonov-Bohm effect. PMID:18795005

Tan, C Z

2008-09-15

92

Aharonov-Bohm effect and resonances in the circular quantum billiard with two leads  

SciTech Connect

We calculate the conductance through a circular quantum billiard with two leads and a point magnetic flux at the center. The boundary element method is used to solve the Schr{umlt o}dinger equation of the scattering problem, and the Landauer formula is used to calculate the conductance from the transmission coefficients. We use two different shapes of leads, straight and conic, and find that the conductance is affected by lead geometry, the relative positions of the leads and the magnetic flux. The Aharonov-Bohm effect can be seen from shifts and splittings of fluctuations. When the flux is equal to h/2e and the angle between leads is 180{degree}, the conductance tends to be suppressed to zero in the low-energy range due to the Aharonov-Bohm effect. {copyright} {ital 1999} {ital The American Physical Society}

Ree, S.; Reichl, L.E. [Center for Studies in Statistical Mechanics and Complex Systems, The University of Texas at Austin, Austin, Texas 78712 (United States)] [Center for Studies in Statistical Mechanics and Complex Systems, The University of Texas at Austin, Austin, Texas 78712 (United States)

1999-03-01

93

Scattering theory and the Aharonov-Bohm effect in quasiclassical physics  

SciTech Connect

Research Highlights: > Scattering Aharonov-Bohm effect. > Short-wavelength limit of scattered nonrelativistic particles. > Fraunhofer diffraction in the forward direction. > Fresnel diffraction in the forward region in conical space. > Enclosed magnetic flux is a gate for the propagation of quasiclassical particles. - Abstract: Scattering of a nonrelativistic quantum-mechanical particle by an impenetrable magnetic vortex is considered. The nonvanishing transverse size of the vortex is taken into account, and the limit of short, as compared to this size, wavelengths of the scattered particle is analyzed. We show that the scattering Aharonov-Bohm effect persists in the quasiclassical limit owing to the diffraction persisting in the short-wavelength limit. As a result, the vortex flux serves as a gate for the propagation of short-wavelength, almost classical, particles. This quasiclassical effect is more feasible to experimental detection in the case when space outside the vortex is conical.

Sitenko, Yurii A., E-mail: yusitenko@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, National Academy of Sciences, 03680 Kyiv (Ukraine); Vlasii, Nadiia D. [Bogolyubov Institute for Theoretical Physics, National Academy of Sciences, 03680 Kyiv (Ukraine); Physics Department, Taras Shevchenko National University of Kyiv, 01601 Kyiv (Ukraine)

2011-06-15

94

Exotic electron states and tunable magneto-transport in a fractal Aharonov-Bohm interferometer  

NASA Astrophysics Data System (ADS)

A Sierpinski gasket fractal network model is studied in respect of its electronic spectrum and magneto-transport when each ‘arm' of the gasket is replaced by a diamond shaped Aharonov-Bohm interferometer, threaded by a uniform magnetic flux. Within the framework of a tight binding model for non-interacting, spinless electrons and a real space renormalization group method we unravel a class of extended and localized electronic states. In particular, we demonstrate the existence of extreme localization of electronic states at a special finite set of energy eigenvalues, and an infinite set of energy eigenvalues where the localization gets ‘delayed' in space (staggered localization). These eigenstates exhibit a multitude of localization areas. The two terminal transmission coefficient and its dependence on the magnetic flux threading each basic Aharonov-Bohm interferometer is studied in details. Sharp switch on-switch off effects that can be tuned by controlling the flux from outside, are discussed. Our results are analytically exact.

Nandy, Atanu; Pal, Biplab; Chakrabarti, Arunava

2014-08-01

95

Aharonov-Bohm effect on trion and biexciton in type-II semiconductor quantum dot  

NASA Astrophysics Data System (ADS)

We theoretically examine optical Aharonov-Bohm (AB) effects on trion and biexciton in the type-II semiconductor quantum dots. Many-particle states are calculated numerically by the exact diagonalization method. Two electrons in trion and biexciton are strongly correlated to each other, forming a Wigner molecule. The magnetoluminescence spectra from trion and biexciton change discontinuously as the magnetic flux increases by half of h/e, reflecting the Wigner moleculization.

Okuyama, Rin; Eto, Mikio; Hyuga, Hiroyuki

2011-12-01

96

Observation of Optical Signature of the Aharonov-Bohm Phase in Type-II Quantum Dots  

Microsoft Academic Search

Recent theoretical studies^1,2 on the optical response of type-II excitons in the magnetic field have shown that the excitons will acquire the Aharonov-Bohm (AB) phase as the electrical dipole, formed due to carrier separation, interacts with the field, resulting in the field dependent exciton energy and the emission intensity. Experimentally, the former has been reported^3; however, the behavior of the

Igor Kuskovsky; W. MacDonald; M. C. Tamargo; A. O. Govorov; X. Wei; M. Tadic; F. M. Peeters

2006-01-01

97

Anticrossing-induced optical excitonic Aharonov-Bohm effect in strained type-I semiconductor nanorings  

Microsoft Academic Search

The exciton states in strained (In,Ga)As nanorings embedded in a GaAs matrix\\u000aare computed. The strain distribution is extracted from the continuum\\u000amechanical model, and the exact diagonalization approach is employed to compute\\u000athe exciton states. Weak oscillations of the ground exciton state energy with\\u000athe magnetic field normal to the ring are an expression of the excitonic\\u000aAharonov-Bohm effect.

M. Tadi?; N. ?ukari?; V. Arsoski; F. M. Peeters

2010-01-01

98

Anticrossing-induced optical excitonic Aharonov-Bohm effect in strained type-I semiconductor nanorings  

Microsoft Academic Search

The exciton states in strained (In,Ga)As nanorings embedded in a GaAs matrix are computed. The strain distribution is extracted from the continuum mechanical model, and the exact diagonalization approach is employed to compute the exciton states. Weak oscillations of the ground exciton state energy with the magnetic field normal to the ring are an expression of the excitonic Aharonov-Bohm effect.

M. Tadic; N. Cukaric; V. Arsoski; F. M. Peeters

2010-01-01

99

Role of the Aharonov–Bohm Phasein the Optical Properties of Carbon Nanotubes  

Microsoft Academic Search

\\u000a A brief review is given on the electronic and optical properties of carbon\\u000a nanotubes with emphasis on Aharonov–Bohm effects. The topics include an\\u000a effective-mass description of the electronic states, optical absorption and excitons,\\u000a their fine structure, optical absorption for perpendicular polarization, and optical\\u000a phonons.

Tsuneya Ando

100

Cross-polarized exciton absorption in carbon nanotubes with Aharonov-Bohm flux  

NASA Astrophysics Data System (ADS)

The Aharonov-Bohm effect on optical absorption of light polarized perpendicularly to the tube axis in semiconducting carbon nanotubes is studied by taking account of exciton and depolarization effect within an effective-mass approximation. The excitation energy and oscillator strength exhibit weak and quadratic dependence on the flux around zero in contrast to the linear dependence for light polarized parallel to the axis.

Uryu, Seiji; Ando, Tsuneya

2007-09-01

101

Influence of Electron-Phonon Interaction on Fano Resonance in Aharonov-Bohm Interferometer  

Microsoft Academic Search

We theoretically study the effect of electron-phonon (e-ph) interaction on a Fano resonance in an Aharonov-Bohm interferometer with an embedded quantum dot. We examine the bias-voltage (V) dependence of the decoherence, using Keldysh Green function method and perturbation with respect to e-ph interaction. With optical phonons of energy omega0, only the elastic process takes place when eV omega0, the inelastic

Akiko Ueda; Mikio Eto

2007-01-01

102

Momentum-transfer scattering cross section and the Aharonov-Bohm effect on a toroidal solenoid  

Microsoft Academic Search

The quantum-mechanical Aharonov-Bohm effect in the diffraction of charged particles by a toroidal solenoid containing a magnetic\\u000a field is investigated. The total and differential elastic scattering cross sections depend on the magnetic flux inside the\\u000a solenoid, even in the presence of a “black” ring-shaped screen which prevents charged particles from entering the region where\\u000a the magnetic field is localized. Relations

V. V. Lyuboshitz; V. L. Lyuboshitz

2000-01-01

103

Polarized excitons in nanorings and the optical Aharonov-Bohm effect  

Microsoft Academic Search

The quantum nature of matter lies in the wave function phases that accumulate\\u000awhile particles move along their trajectories. A prominent example is the\\u000aAharonov-Bohm phase, which has been studied in connection with the conductance\\u000aof nanostructures. However, optical response in solids is determined by neutral\\u000aexcitations, for which no sensitivity to magnetic flux would be expected. We\\u000apropose a

A. O. Govorov; K. Karrai; R. J. Warburton

2002-01-01

104

Two-Slit and Aharonov-Bohm Experiments in Magnetic Field  

Microsoft Academic Search

We discuss the two-slit experiment and the Aharonov-Bohm (AB) experiment in the magnetic field. In such a case the electron\\u000a moving in the magnetic field produces so called synchrotron radiation. In other words the photons are emitted from the points\\u000a of the electron trajectory and it means that the trajectory of electron is visible in the synchrotron radiation spectrum.\\u000a The

Miroslav Pardy

2008-01-01

105

VOLUME 87, NUMBER 4 P H Y S I C A L R E V I E W L E T T E R S 23 JULY 2001 Nonlinear Aharonov-Bohm Scattering by Optical Vortices  

E-print Network

. In this Letter we study an optical analog of the Aharonov-Bohm effect--the wave scattering by an optical vortex. This phenomenon is known these days as the Aharonov-Bohm effect [1], and it was shown to have a more general geo with the Aharonov-Bohm effect, allowing one to observe directly the macroscopic aspects of the geo- metrical phases

106

Many-electron transport in Aharonov-Bohm interferometers: A time-dependent density-functional study  

NASA Astrophysics Data System (ADS)

We apply time-dependent density-functional theory to study many-electron transport in Aharonov-Bohm interferometers in a non-equilibrium situation. The conductance properties in the system are complex and depend on the enclosed magnetic flux in the interferometer, the number of interacting electrons, and the mutual distance of the transport channels at the points of encounter. Generally, the electron-electron interactions do not suppress the visibility of Aharonov-Bohm oscillations if the interchannel distance — determined by the positioning of the incompressible strips through the external magnetic field - is optimized. However, the interactions also impose an interesting Aharonov-Bohm phase shift with channel distances below or above the optimal one. This effect is combined with suppressed oscillation amplitudes. We analyze these effects within different approximations for the exchange-correlation potential in time-dependent density-functional theory.

Salman, Aysevil; Kotimäki, Ville; S?dd?ki, Afif; Räsänen, Esa

2013-04-01

107

Coherent Aharonov-Bohm oscillations in type-II (Zn,Mn)Te\\/ZnSe quantum dots  

Microsoft Academic Search

The magneto-photoluminescence of type-II (ZnMn)Te quantum dots is presented.\\u000aAs a result of the type-II band alignment Aharonov-Bohm (AB) oscillations in\\u000athe photoluminescence intensity are evident, confirming previous predictions\\u000afor the suitability of this geometry to control the optical Aharonov-Bohm\\u000aeffect in semiconductor systems. Moreover, the system demonstrates an\\u000ainteresting interplay between the AB effect and the spin polarization in

I. R. Sellers; V. R. Whiteside; A. O. Govorov; W. C. Fan; I. Khan; A. Petrou; B. D. McCombe

2008-01-01

108

Electric field tuning of the optical excitonic Aharonov-Bohm effect in nanodots grown by droplet epitaxy  

NASA Astrophysics Data System (ADS)

Neutral excitons in axially symmetric GaAs nanodots embedded in an (Al,Ga)As matrix, which are formed by the droplet epitaxy technique, are investigated theoretically. An electric field perpendicular to the nanodot base results in both a vertical and an in-plane exciton polarization, which is beneficial for the appearance of the excitonic Aharonov-Bohm effect. In the range of low magnetic fields (below 5 Tesla), we found that the bright and dark exciton states can cross twice. This results in oscillations of the photoluminescence intensity with magnetic field, which are a striking manifestation of the optical excitonic Aharonov-Bohm effect.

Arsoski, V.; Tadi?, M.; Peeters, F. M.

2013-11-01

109

Force-Free Gravitational Redshift: Proposed Gravitational Aharonov-Bohm Experiment  

NASA Astrophysics Data System (ADS)

We propose a feasible laboratory interferometry experiment with matter waves in a gravitational potential caused by a pair of artificial field-generating masses. It will demonstrate that the presence of these masses (and, for moving atoms, time dilation) induces a phase shift, even if it does not cause any classical force. The phase shift is identical to that produced by the gravitational redshift (or time dilation) of clocks ticking at the atom’s Compton frequency. In analogy to the Aharonov-Bohm effect in electromagnetism, the quantum mechanical phase is a function of the gravitational potential and not the classical forces.

Hohensee, Michael A.; Estey, Brian; Hamilton, Paul; Zeilinger, Anton; Müller, Holger

2012-06-01

110

Gate controlled Aharonov-Bohm-type oscillations from single neutral excitons in quantum rings  

NASA Astrophysics Data System (ADS)

We report on a magnetophotoluminescence study of single self-assembled semiconductor nanorings which are fabricated by molecular-beam epitaxy combined with AsBr3 in situ etching. Oscillations in the neutral exciton radiative recombination energy and in the emission intensity are observed under an applied magnetic field. Further, we control the period of the oscillations with a gate potential that modifies the exciton confinement. We infer from the experimental results, combined with calculations, that the exciton Aharonov-Bohm effect may account for the observed effects.

Ding, F.; Akopian, N.; Li, B.; Perinetti, U.; Govorov, A.; Peeters, F. M.; Bof Bufon, C. C.; Deneke, C.; Chen, Y. H.; Rastelli, A.; Schmidt, O. G.; Zwiller, V.

2010-08-01

111

Optical Aharonov-Bohm oscillations in InGaAs quantum wells  

NASA Astrophysics Data System (ADS)

The intensity of photoluminescence emission in InGaAs/GaAs quantum wells (QWs) exhibits local maxima as a function of magnetic field applied perpendicular to the QW plane at low temperatures. These maxima are attributed to the optical Aharonov-Bohm effect associated with spatially indirect excitons that are formed in the vicinity of indium-rich InGaAs islands within the QW. Analysis of the data yields the radius of the exciton. The exciton linewidth also oscillates with the magnetic field and exhibits maxima that are shifted slightly to higher field values than those of the luminescence intensity maxima.

Schweidenback, L.; Ali, T.; Russ, A. H.; Murphy, J. R.; Cartwright, A. N.; Petrou, A.; Li, C. H.; Yakes, M. K.; Kioseoglou, G.; Jonker, B. T.; Govorov, A.

2012-06-01

112

Optical analogue of the Aharonov-Bohm effect using anisotropic media  

NASA Astrophysics Data System (ADS)

We show that in the context of paraxial optics, which can be analyzed through a wave equation similar to the non-relativistic Schrödinger equation of quantum mechanics but replacing time t by spatial coordinate z, the existence of a vector potential A mimicking the magnetic vector potential in quantum mechanics is allowed by specific gauge symmetries of the optical field in a medium with anisotropic refractive index. In this way, we use Feynman's path integral to demonstrate an optical analogue of the quantum-mechanical Aharonov-Bohm effect, encouraging the search for another optical systems with analogies with more complex quantum field theories.

Dartora, C. A.; Nobrega, K. Z.; Cabrera, G. G.

2011-06-01

113

Higher-order topological phase: generalizations of the Aharonov-Bohm and Josephson effects  

NASA Astrophysics Data System (ADS)

In the magnetic Aharonov-Bohm effect a semiclassical path of a charged particle is gaussian linked with a magnetic flux tube and one observes an interference phase angle proportional to the magnitude of the enclosed flux. We first generalize to the case of knotted paths. Then we argue that quantum mechanical wave functions with semiclassical paths that have higher order linking to multiple magnetic flux tubes have interference angle proportional to the product of the fluxes. Similar results hold for generalizing the Josephson effect.

Buniy, Roman V.; Kephart, Thomas W.

2014-10-01

114

Charging and double-frequency Aharonov-Bohm effects in an open system  

NASA Astrophysics Data System (ADS)

We have investigated experimentally an open semiconductor system in which electron confinement around an obstacle is obtained using a magnetic field. The magnetic field gives rise to Landau levels, and each associated edge state circulates around the obstacle, forming a set of quantized states. Tunable constrictions are fabricated by using a technique which enables us to control transport in and out of these states, producing Aharonov-Bohm oscillations as the magnetic field is swept. Surprisingly, a strong extra oscillation with the same h/e frequency develops, phase shifted by ? so that the frequency appears to have doubled. We explain these results in terms of charging of isolated circulating edge states.

Ford, C. J. B.; Simpson, P. J.; Zailer, I.; Mace, D. R.; Yosefin, M.; Pepper, M.; Ritchie, D. A.; Frost, J. E. F.; Grimshaw, M. P.; Jones, G. A. C.

1994-06-01

115

The Aharonov-Bohm effect in the fractional quantum Hall regime  

NASA Astrophysics Data System (ADS)

We have investigated experimentally resonant tunnelling through single-particle states formed around an antidot by a magnetic field, in the fractional quantum Hall regime. For 1/3 filling factor around the antidot, Aharonov-Bohm oscillations are observed with the same magnetic field period as in the integer quantum Hall regime. All our measurements are consistent with quasiparticles of fractional charge e*. However, the results are also consistent with particles of any charge (? e*) as the system must rearrange every time the flux enclosed increases by h/ e.

Franklin, J. D. F.; Zailer, I.; Ford, C. J. B.; Simpson, P. J.; Frost, J. E. F.; Ritchie, D. A.; Simmons, M. Y.; Pepper, M.

1996-07-01

116

Analogue Aharonov-Bohm effect in a Lorentz-violating background  

NASA Astrophysics Data System (ADS)

In this paper, we consider the acoustic black hole metrics obtained from a relativistic fluid under the influence of constant background that violates the Lorentz symmetry to study the analogue of the Aharonov-Bohm (AB) effect. We show that the scattering of planar waves by a draining bathtub vortex leads to a modified AB effect and due to the Lorentz symmetry breaking, the phase shift persists even in the limit where the parameters associated with the circulation and draining vanish. In this limit, the Lorentz-violating background forms a conical defect, which is also responsible for the appearance of the analogue AB effect.

Anacleto, M. A.; Brito, F. A.; Passos, E.

2012-12-01

117

Scattering theory and the Aharonov--Bohm effect in quasiclassical physics  

E-print Network

Scattering of a nonrelativistic quantum-mechanical particle by an impenetrable magnetic vortex is considered. The nonvanishing transverse size of the vortex is taken into account, and the limit of short, as compared to this size, wavelengths of the scattered particle is analyzed. We show that the scattering Aharonov-Bohm effect persists in the quasiclassical limit owing to the diffraction persisting in the short-wavelength limit. As a result, the vortex flux serves as a gate for the propagation of short-wavelength, almost classical, particles. This quasiclassical effect is more feasible to experimental detection in the case when space outside the vortex is conical.

Sitenko, Yurii A

2010-01-01

118

Aharonov-Bohm effect: influence of the electron's field, and speculations on the possibility of shielding  

SciTech Connect

Aharonov-Bohm (AB) effect is discussed from a viewpoint which stresses the influence of the fields whose source is the scattered particle. Speculations are presented to suggest that AB scattering may be influenced by subtle properties of superconducting surfaces which may shield the particle's fields away from the external magnetic field. Experiments are required to test the reality of such speculations. If such shielding effects can be measured, AB effect may become a sensitive probe to search for unusual surface states which display off diagonal long range order.

Peshkin, M.

1983-01-01

119

Influence of Induced Charges in the Electric Aharonov-Bohm Effect  

E-print Network

This paper states that the induced charge should not be neglected in the electric Aharonov-Bohm effect. If the induced charge is taken into account, the interference pattern of the moving charge will not change with the potential difference between the two metal tubes. It means that the scale potential itself can not affect the phase of the moving charge, and the true factor affecting the phase of the moving charge is the energy of the system including the moving charge and the induced charge.

Rui-Feng Wang

2014-09-24

120

Anyonic strings and membranes in anti-de Sitter space and dual Aharonov-Bohm effects.  

PubMed

It is observed that strings in AdS(5) x S(5) and membranes in AdS(7) x S(4) exhibit long range phase interactions. Two well separated membranes dragged around one another in anti-de Sitter space (AdS) acquire phases of 2 pi/N. The same phases are acquired by a well separated F and D string dragged around one another. The phases are shown to correspond to both the standard and a novel type of Aharonov-Bohm effect in the dual field theory. PMID:17501041

Hartnoll, Sean A

2007-03-16

121

Excitonic Aharonov-Bohm effect in a two-dimensional quantum ring  

SciTech Connect

We study theoretically the optical properties of an exciton in a two-dimensional ring threaded by a magnetic flux. We model the quantum ring by a confining potential that can be continuously tuned from strictly one-dimensional to truly two-dimensional with finite radius-to-width ratio. We present an analytic solution of the problem when the electron-hole interaction is short ranged. The oscillatory dependence of the oscillator strength as a function of the magnetic flux is attributed to the Aharonov-Bohm effect. The amplitude of the oscillations changes upon increasing the width of the quantum ring. We find that the Aharonov-Bohm oscillations of the ground state of the exciton decrease with increasing the width, but, remarkably, the amplitude remains finite down to radius-to-width ratios less than unity. We attribute this resilience of the excitonic oscillations to the nonsimple connectedness of our chosen confinement potential with its centrifugal core at the origin.

Gonzalez-Santander, C.; Dominguez-Adame, F. [Departamento de Fisica de Materiales, Universidad Complutense de Madrid, ES-28040 (Spain); Roemer, R. A. [Department of Physics and Centre for Scientific Computing, University of Warwick, Coventry, CV4 7AL (United Kingdom)

2011-12-15

122

Excitonic Aharonov-Bohm effect in a two-dimensional quantum ring  

NASA Astrophysics Data System (ADS)

We study theoretically the optical properties of an exciton in a two-dimensional ring threaded by a magnetic flux. We model the quantum ring by a confining potential that can be continuously tuned from strictly one-dimensional to truly two-dimensional with finite radius-to-width ratio. We present an analytic solution of the problem when the electron-hole interaction is short ranged. The oscillatory dependence of the oscillator strength as a function of the magnetic flux is attributed to the Aharonov-Bohm effect. The amplitude of the oscillations changes upon increasing the width of the quantum ring. We find that the Aharonov-Bohm oscillations of the ground state of the exciton decrease with increasing the width, but, remarkably, the amplitude remains finite down to radius-to-width ratios less than unity. We attribute this resilience of the excitonic oscillations to the nonsimple connectedness of our chosen confinement potential with its centrifugal core at the origin.

González-Santander, C.; Domínguez-Adame, F.; Römer, R. A.

2011-12-01

123

Enhanced spin figure of merit in an Aharonov-Bohm ring with a double quantum dot  

NASA Astrophysics Data System (ADS)

We theoretically investigate the thermoelectric effects in an Aharonov-Bohm ring with a serially coupled double quantum dot embedded in one arm. An external magnetic field is perpendicularly applied to the two dots. Using the nonequilibrium Green's function method in the linear-response regime, we calculate the charge and spin figures of merit. When the energy levels of the two quantum dots are equal and the system is connected to two normal leads, a large spin figure of merit (ZsT ? 4.5) accompanying with a small charge figure of merit (ZcT ? 0) can be generated due to the remarkable bipolar effect. Further, when the system is connected to two ferromagnetic leads, the spin figure of merit can reach even a higher value about 9. Afterwards, we find that ZsT is enhanced while ZcT is reduced in the coaction of the Aharonov-Bohm flux and Rashba spin-orbit coupling. It is argued that the bipolar effect is positive (negative) to spin (charge) figure of merit in the presence of level detuning of the two quantum dots and intradot Coulomb interactions, respectively. Also, we propose a possible experiment to verify our results.

Zhou, Xingfei; Qi, Fenghua; Jin, Guojun

2014-04-01

124

Anomalous interference in Aharonov-Bohm rings with two Majorana bound states  

NASA Astrophysics Data System (ADS)

We investigate the conductance of an Aharonov-Bohm (AB) interferometer coupled to a quantum dot and two Majorana bound states on the edge of the topological superconductor with finite length. When the tunnel couplings between the Majorana bound states and the Aharonov-Bohm interferometer are fixed to the specific phase, the differential conductance becomes zero irrespective of all the parameters as long as the hoppings to the two Majorana fermions on the opposite side are equal. The conductance at the zero bias voltage does not change with the magnetic flux penetrating the ring for all cases. When the energy level of the quantum dot is equal to the energy of the Majorana bound states, the AB oscillation shows ? periodicity due to the particle-hole symmetry. The breaking of the time-reversal symmetry of the topological superconductor results in 2? periodicity of the AB oscillation for the specific phase of the tunnel coupling while the time-reversal symmetry breaking leads to the mixing of the triplet and singlet states in the quantum dot in another specific phase.

Ueda, Akiko; Yokoyama, Takehito

2014-08-01

125

Optical detection of the Aharonov-Bohm effect on a charged particle in a nanoscale quantum ring.  

PubMed

We study spectroscopically the current produced by a charged particle moving in a nanosize semiconductor quantum ring subject to a perpendicular magnetic field. Several Aharonov-Bohm oscillations are observed in the emission of a charged exciton confined in a single ring structure. The magnetic field period of the oscillations correlates well with the size of the rings. PMID:12786035

Bayer, M; Korkusinski, M; Hawrylak, P; Gutbrod, T; Michel, M; Forchel, A

2003-05-01

126

Effect of the Aharonov-Bohm potential on the optical polaron in a one-dimensional ring  

Microsoft Academic Search

The effect of the Aharonov-Bohm potential on the optical polaron is discussed. In the case of the small magnetic flux the continuous limit is taken and the analytic solution is given. The parameters of the soliton-type solution, such as the height and width of wave packet, the travelling velocity, the lattice deformation and the total energy, is showed to be

Zhou Yi-Chang; Fang Yi-Zhong; He Guang-Ping

1996-01-01

127

Optically mediated spin current and Fano resonance in an Aharonov–Bohm ring with a quantum dot  

Microsoft Academic Search

We study the spin-polarized transport and Fano resonance in an Aharonov–Bohm (AB) interferometer with an embedded quantum dot, where the dot is irradiated by continuous circularly polarized light. Compared with the conventional Fano form, the resonance line shape is found to be deformed by the interplay between the external irradiation and the Coulomb repulsion. The Fano resonance peaks are split

Sha-Sha Ke; Hai-Feng Lü; Huai-Wu Zhang

2011-01-01

128

Noncircular semiconductor nanorings of types I and II: Emission kinetics in the excitonic Aharonov-Bohm effect  

Microsoft Academic Search

Transition energies and oscillator strengths of excitons in dependence on magnetic field are investigated in types I and II semiconductor nanorings. A slight deviation from circular (concentric) shape of the type II nanoring gives a better observability of the Aharonov-Bohm oscillations since the ground state is always optically active. Kinetic equations for the exciton occupation are solved with acoustic phonon

Michal Grochol; Roland Zimmermann

2007-01-01

129

Optical Detection of the Aharonov-Bohm Effect on a Charged Particle in a Nanoscale Quantum Ring  

Microsoft Academic Search

We study spectroscopically the current produced by a charged particle moving in a nanosize semiconductor quantum ring subject to a perpendicular magnetic field. Several Aharonov-Bohm oscillations are observed in the emission of a charged exciton confined in a single ring structure. The magnetic field period of the oscillations correlates well with the size of the rings.

M. Bayer; M. Korkusinski; P. Hawrylak; T. Gutbrod; M. Michel; A. Forchel

2003-01-01

130

On the spin- 1/2 Aharonov–Bohm problem in conical space: Bound states, scattering and helicity nonconservation  

SciTech Connect

In this work the bound state and scattering problems for a spin- 1/2 particle undergone to an Aharonov–Bohm potential in a conical space in the nonrelativistic limit are considered. The presence of a ?-function singularity, which comes from the Zeeman spin interaction with the magnetic flux tube, is addressed by the self-adjoint extension method. One of the advantages of the present approach is the determination of the self-adjoint extension parameter in terms of physics of the problem. Expressions for the energy bound states, phase-shift and S matrix are determined in terms of the self-adjoint extension parameter, which is explicitly determined in terms of the parameters of the problem. The relation between the bound state and zero modes and the failure of helicity conservation in the scattering problem and its relation with the gyromagnetic ratio g are discussed. Also, as an application, we consider the spin- 1/2 Aharonov–Bohm problem in conical space plus a two-dimensional isotropic harmonic oscillator. -- Highlights: •Planar dynamics of a spin- 1/2 neutral particle. •Bound state for Aharonov–Bohm systems. •Aharonov–Bohm scattering. •Helicity nonconservation. •Determination of the self-adjoint extension parameter.

Andrade, F.M., E-mail: fmandrade@uepg.br [Departamento de Matemática e Estatística, Universidade Estadual de Ponta Grossa, 84030-900 Ponta Grossa-PR (Brazil); Silva, E.O., E-mail: edilbertoo@gmail.com [Departamento de Física, Universidade Federal do Maranhão, Campus Universitário do Bacanga, 65085-580 São Luís-MA (Brazil); Pereira, M., E-mail: marciano@uepg.br [Departamento de Matemática e Estatística, Universidade Estadual de Ponta Grossa, 84030-900 Ponta Grossa-PR (Brazil)

2013-12-15

131

Electron matter optics of the Aharonov-Bohm and Stern-Gerlach effects  

NASA Astrophysics Data System (ADS)

Since the advent of quantum mechanics and the idea that massive particles exhibit wave properties, physicists have made efforts to make use of the short deBroglie wave length of matter waves for fundamental as well as practical studies. Among these are the precise measurements allowed by interference, diffraction, and microscopy as well as the study of more fundamental aspects of quantum theory such as the Aharonov-Bohm effects or the Stern-Gerlach effect, which are described below. However, in order to use matter waves to observe any of these effects it is necessary to produce and maintain coherence in the waves which are used for measurement. With a grasp of what coherence is and how it may be achieved and maintained one can move forward to study the interesting phenomena associated with coherent matter waves. More specifically in this work the interference and diffraction of electron matter waves are considered. The phenomena under consideration are those associated with the interaction of the electric charge and magnetic dipole moment of the electron with external fields and potentials while in the process of interfering or diffracting. Namely the focus of this dissertation is the Aharonov-Bohm effect, the Aharonov-Casher effect, and the Stern-Gerlach effect. Additionally, a wide-angle electron beam-splitter capable of producing two centimeter beam separation at the detection plane is discussed. The beam-splitter utilizes a nanofabricated periodic grating in combination with a bi-prism element. Contrary to devices utilizing only bi-prism elements, the use of the periodic grating causes amplitude, and not wave front, splitting. Even at maximum separation, beam profiles remain undistorted, providing evidence that coherence is intact. This is a step towards the realization of a large area electron interferometer using such a grating bi-prism combination. Such an interferometer could, in principle, be used to test the dispersionless nature of the Aharonov-Bohm effect. Work towards such an interferometer and possible future work are also discussed.

McGregor, Scot Cameron

132

Classical light analogue of the non-local Aharonov-Bohm effect  

NASA Astrophysics Data System (ADS)

We demonstrate the existence of a non-local geometric phase in the intensity-intensity correlations of classical incoherent light, that is not seen in the lower-order correlations. This two-photon Pancharatnam phase was observed and modulated in a Mach-Zehnder interferometer. Using acousto-optic interaction, independent phase noise was introduced to light in the two arms of the interferometer to create two independent incoherent classical sources from laser light. The experiment is the classical optical analogue of the multi-particle Aharonov-Bohm effect. As the trajectory of light over the Poincaré sphere introduces a phase shift observable only in the intensity-intensity correlation, it provides a means of deflecting the two-photon wavefront, while having no effect on single photons.

Satapathy, Nandan; Pandey, Deepak; Mehta, Poonam; Sinha, Supurna; Samuel, Joseph; Ramachandran, Hema

2012-03-01

133

Optical Aharonov-Bohm effect on Wigner molecules in type-II semiconductor quantum dots  

NASA Astrophysics Data System (ADS)

We theoretically examine the magnetoluminescence from a trion and a biexciton in a type-II semiconductor quantum dot, in which holes are confined inside the quantum dot and electrons are in a ring-shaped region surrounding the quantum dot. First, we show that two electrons in the trion and biexciton are strongly correlated to each other, forming a Wigner molecule: Since the relative motion of electrons is frozen, they behave as a composite particle whose mass and charge are twice those of a single electron. As a result, the energy of the trion and biexciton oscillates as a function of magnetic field with half the period of the single-electron Aharonov-Bohm oscillation. Next, we evaluate the photoluminescence. Both the peak position and peak height change discontinuously at the transition of the many-body ground state, implying a possible observation of the Wigner molecule by the optical experiment.

Okuyama, Rin; Eto, Mikio; Hyuga, Hiroyuki

2011-05-01

134

The interplay between the Aharonov-Bohm interference and parity selective tunneling in graphene nanoribbon rings.  

PubMed

We report on a numerical study of the Aharonov-Bohm (AB) effect and parity selective tunneling in pn junctions based on rectangular graphene rings where the contacts and ring arms are all made of zigzag nanoribbons. We find that when applying a magnetic field to the ring, the AB interference can reverse the parity symmetry of incoming waves and hence can strongly modulate the parity selective transmission through the system. Therefore, the transmission between two states of different parity exhibits the AB oscillations with a ?-phase shift, compared to the case of states of the same parity. On this basis, it is shown that interesting effects, such as giant (both positive and negative) magnetoresistance and strong negative differential conductance, can be achieved in this structure. Our study thus presents a new property of the AB interference in graphene nanorings, which could be helpful for further understanding the transport properties of graphene mesoscopic systems. PMID:24785639

Nguyen, V Hung; Niquet, Y-M; Dollfus, P

2014-05-21

135

Gaussian curvature and global effects: Gravitational Aharonov-Bohm effect revisited  

NASA Astrophysics Data System (ADS)

By using the Gauss-Bonnet formula, the integral of the Gaussian curvature over a 2-surface enclosed by a curve in the asymptotically flat region of a static spacetime was found to be a measure of a gravitational analogue of the Aharonov-Bohm effect by Ford and Vilenkin in the linearized regime. Employing the 1+3 formulation of spacetime decomposition, we study the same effect in the context of the full Einstein field equations for stationary spacetimes. Applying our approach to static tubelike and cylindrical distributions of dust, not only do we recover their result but we also obtain an extra term which is interpreted to be representing the classical version of the Colella-Overhauser-Werner effect (the Colella-Overhauser-Werner experiment).

Nouri-Zonoz, M.; Parvizi, A.

2013-07-01

136

The manifestly covariant Aharonov-Bohm effect in terms of the 4D fields  

E-print Network

In this paper it is presented a manifestly covariant formulation of the Aharonov-Bohm (AB) phase difference for the magnetic AB effect . This covariant AB phase is written in terms of the Faraday 2-form F and using the decomposition of F in terms of the electric and magnetic fields as four-dimensional (4D) geometric quantities. It is shown that there is a static electric field outside a stationary solenoid with resistive conductor carrying steady current, which causes that the AB phase difference in the magnetic AB effect may be determined by the electric part of the covariant expression, i.e. by the local influence of the 4D electric field and not, as generally accepted,in terms of nonzero vector potential.

Tomislav Ivezic

2014-07-14

137

Transport properties of a single-quantum dot Aharonov-Bohm interferometer  

NASA Astrophysics Data System (ADS)

We consider a two-terminal Aharonov-Bohm (AB) interferometer with a quantum dot inserted in one path of the AB ring. We investigate the transport properties of this system in and out of the Kondo regime. We utilize perturbation theory to calculate the electron self-energy of the quantum dot with respect to the intradot Coulomb interaction. We show the expression of the Kondo temperature as a function of the AB phase together with its dependence on other characteristics such as the linewidth of the ring and the finite Coulomb interaction and the energy levels of the quantum dot. The current oscillates periodically as a function of the AB phase. The amplitude of the current oscillation decreases with increasing Coulomb interaction. For a given temperature, the electron transport through the AB interferometer can be selected to be in or out of the Kondo regime by changing the magnetic flux threading perpendicular to the AB ring of the system.

Son, D. N.; Arboleda, N., Jr.; Dino, W. A.; Kasai, H.

2007-05-01

138

Thermoelectric effect in an Aharonov-Bohm ring with an embedded quantum dot  

PubMed Central

Thermoelectric effect is studied in an Aharonov-Bohm interferometer with an embedded quantum dot (QD) in the Coulomb blockade regime. The electrical conductance, electron thermal conductance, thermopower, and thermoelectric figure-of-merit are calculated by using the Keldysh Green's function method. It is found that the figure-of-merit ZT of the QD ring may be quite high due to the Fano effect originated from the quantum interference effect. Moreover, the thermoelectric efficiency is sensitive to the magnitude of the dot-lead and inter-lead coupling strengthes. The effect of intradot Coulomb repulsion on ZT is significant in the weak-coupling regime, and then large ZT values can be obtained at rather high temperature. PMID:22369454

2012-01-01

139

Observation of the scalar Aharonov-Bohm effect by neutron interferometry  

NASA Astrophysics Data System (ADS)

A phase shift for de Broglie waves due to the action of a scalar potential in an otherwise field-free (i.e. force-free) region of space is known as the scalar Aharonov-Bohm (AB) effect. Unlike the more familiar AB effect due to the magnetic vector potential, the scalar effect has hitherto remained unverified due, presumably, to technical difficulties in electron interferometry. An analogous interferometric experiment was performed with thermal neutrons subject to pulsed magnetic fields. The observations were carried out at the University of Missouri Research Reactor, using a skew-symmetric perfect silicon crystal neutron interferometer. The expected phase shifts have been observed to a high degree of accuracy. A detailed description of the experiment and its interpretation is given.

Allman, B. E.; Cimmino, A.; Klein, A. G.; Opat, G. I.; Kaiser, H.; Werner, S. A.

140

Interference Signatures of Abelian and Non-Abelian Aharonov-Bohm effect on Neutral Atoms in Optical Lattices  

NASA Astrophysics Data System (ADS)

We propose a scheme to generate an effective Abelian U(1) or non-Abelian SU(2) gauge field for cold neutral atoms in a ring- or square-shaped optical lattice by using Laguerre-Gauss lasers. The synthetic field produced is strongly localized, which allows us to study the Aharonov-Bohm effect on the neutral atoms. By preparing a coherent state of atoms initially and allowing them to evolve along two different paths enclosing the generated magnetic field, we obtain interference signatures of the Aharonov-Bohm effect with distinctly different patterns in the detection area for systems exposed to a zero, an Abelian U(1) or a non-Abelian SU(2) gauge field.

Huo, Ming-Xia; Wei, Nie; Hutchinson, David A. W.; Kwek, Leong Chuan

2013-03-01

141

Electron vortex beams in a magnetic field: A new twist on Landau levels and Aharonov-Bohm states  

E-print Network

We examine the propagation of recently-discovered electron vortex beams in a longitudinal magnetic field. Both the Aharonov-Bohm configuration with a single flux line and the Landau case of a uniform magnetic field are considered. While stationary Aharonov-Bohm modes represent Bessel beams with field-dependent probability and current distributions, stationary Landau states manifest themselves as non-diffracting Laguerre-Gaussian beams. Furthermore, the Landau-state beams possess field- and vortex-dependent phases: (i) the Zeeman phase from coupling the quantized angular momentum to the magnetic field and (ii) the Gouy phase, known from optical Laguerre-Gaussian beams. Remarkably, together these phases determine the structure of Landau energy levels. This unified Zeeman-Landau-Gouy phase manifests itself in a nontrivial evolution of images formed by various superpositions of modes. We demonstrate that, depending on the chosen superposition, the image can rotate in a magnetic field with either Larmor, cyclotron...

Bliokh, Konstantin Y; Verbeeck, Jo; Nori, Franco

2012-01-01

142

Coherent Aharonov-Bohm oscillations in type-II (Zn,Mn)Te\\/ZnSe quantum dots  

Microsoft Academic Search

The magneto-photoluminescence of type-II (Zn,Mn)Te quantum dots is presented. As a result of the type-II band alignment, Aharonov-Bohm (AB) oscillations in the photoluminescence intensity are evident. In addition, an interesting interplay between the AB effect and the spin polarization in these diluted magnetic semiconductor quantum dots is observed. The intensity of the AB oscillations increases with both magnetic field and

I. R. Sellers; V. R. Whiteside; A. O. Govorov; W. C. Fan; W.-C. Chou; I. Khan; A. Petrou; B. D. McCombe

2008-01-01

143

Aharonov-Bohm Excitons at Elevated Temperatures in Type-II ZnTe\\/ZnSe Quantum Dots  

Microsoft Academic Search

Optical emission from type-II ZnTe\\/ZnSe quantum dots demonstrates large and persistent oscillations in both the peak energy and intensity indicating the formation of coherently rotating states. Furthermore, these Aharonov-Bohm oscillations are shown to be remarkably robust and persist until 180 K. This is at least one order of magnitude greater than the typical temperatures in lithographically defined rings. To our

I. R. Sellers; V. R. Whiteside; I. L. Kuskovsky; A. O. Govorov; B. D. McCombe

2008-01-01

144

Physical Optics, the Sagnac Effect, and the Aharonov-Bohm Effect in the Evans Unified Field Theory  

Microsoft Academic Search

A generally covariant and gauge invariant description of physical optics, the Sagnac effect, and the Aharonov-Bohm (AB) effect is developed using the appropriate phase factor for electrodynamics. The latter is a generally covariant development of the Dirac-Wu-Yang phase factor based on the generally covariant Stokes theorem. The Maxwell-Heaviside (MH) field theory fails to describe physical optics, interferometry, and topological phase

Myron W. Evans

2004-01-01

145

Enhancement of the Aharonov-Bohm effect of neutral excitons in semiconductor nanorings with an electric field  

Microsoft Academic Search

This work demonstrates that the Aharonov-Bohm effect for excitons, practically indistinguishable from the numerical noise without an applied electric field, becomes clearly evident in the optical absorption once the electric field is applied in the plane containing the nanoring. The enhancement arises as a result of the field-induced delocalization of the relative electron-hole motion around the entire ring. The excitonic

A. V. Maslov; D. S. Citrin

2003-01-01

146

Slow photons as charged quasi-particles, and photonic Aharonov-Bohm effect  

NASA Astrophysics Data System (ADS)

Recently we have proposed the method of Raman Adiabatic Transfer of Optical States (RATOS) to manipulate the optical state of light. A four-level atomic medium in double-? configuration is interacting with two pump fields and a signal photon with very slow group velocity. An adiabatic change in time of the pump fields can then generate a slow photon in a superposition of different frequencies. Here we theoretically analyze the influence of an adiabatic change in the spatial form of the pump fields. We demonstrate that the signal photon then behaves like a charged quasi-particle: in paraxial approximation its dynamics is governed by a Schr"odinger-like equation that includes a scalar and a vector potential whose form is determined by the shape of the pump fields. We suggest pump field configurations that generate potentials corresponding to a constant electric and a constant magnetic field. Furthermore we devise a scheme of pump fields that generates a vector potential of Aharonov-Bohm type which induces a topological phase shift for slow photons.

Marzlin, Karl-Peter; Appel, Juergen; Lvovsky, Alexander

2007-06-01

147

Optical Aharonov-Bohm Effect for type-II InAs Quantum Dots  

NASA Astrophysics Data System (ADS)

The magnetic field dependence of the ground- and excited-state transitions in InAs quantum dots (QD), capped with a strain reducing layer of GaAs0.76Sb0.26, which results in a type-II band alignment, has been studied by magneto-photoluminescence (magneto-PL) spectroscopy. Oscillations in the PL intensity of both the excited state and ground state magneto-PL are observed. Similar oscillations in intensity have been previously attributed to the Optical Aharonov-Bohm (OAB) effect in other type-II QD systems. In the present case the ground state oscillations are only observed at low excitation power, for which only the ground state is occupied. At higher excitation power the excited state oscillations are more pronounced than the ground state oscillations. The room temperature emission wavelength of these QDs matches the optical telecommunications window at 1.55 ?m, so the OAB effect in these structures may be useful in future devices.

Whiteside, Vincent R.; Sellers, Ian R.; McCombe, Bruce D.; Liu, Huiyun

2009-03-01

148

Effect of vacuum polarization of charged massive fermions in an Aharonov--Bohm field  

E-print Network

The effect of vacuum polarization of charged massive fermions in an Aharonov-Bohm (AB) potential in 2+1 dimensions is investigated. The causal Green's function of the Dirac equation with the AB potential is represented via the regular and irregular solutions of the two-dimensional radial Dirac equation. It is shown that the vacuum current density contains the contribution from free filled states of the negative energy continuum as well as that from a bound unfilled state, which can emerge in the above background due to the interaction of the fermion spin magnetic moment with the AB magnetic field while the induced charge density contains only the contribution from the bound state. The expressions for the vacuum charge and induced current densities are obtained (recovered for massless fermions) for the graphene in the field of infinitesimally thin solenoid perpendicular to the plane of a sample. We also find the bound state energy as a function of magnetic flux, fermion spin and the radius of solenoid as well as discuss the role of the so-called self-adjoint extension parameter and determine it in terms of the physics of the problem.

V. R. Khalilov

2014-07-04

149

Classical Interaction of a Magnet and a Point Charge: The Classical Electromagnetic Forces Responsible for the Aharonov-Bohm Phase Shift  

E-print Network

A new classical electromagnetic analysis is presented suggesting that the Aharonov-Bohm phase shift is overwhelmingly likely to arise from a classical lag effect based upon classical electromagnetic forces. The analysis makes use of several aspects of classical electromagnetic theory which are unfamiliar to most physicists, including the Darwin Lagrangian, acceleration-based electric fields, internal electromagnetic momentum in a magnet, and a magnet model involving at least three mutually-interacting particles. Only when the acceleration-based electric forces acting on the passing charge are included do we find consistency with all the relativistic conservation laws: energy, linear momentum, angular momentum, and constant center-of-mass velocity. The electric forces on the passing charge lead to a lag effect which accounts quantitatively for the Aharonov-Bohm phase shift. Thus the classical analysis strongly suggests that the Aharonov-Bohm phase shift (observed when electrons pass a long solenoid which corre...

Boyer, Timothy H

2014-01-01

150

Aharonov-Bohm Excitons at Elevated Temperatures in Type-II ZnTe/ZnSe Quantum Dots  

NASA Astrophysics Data System (ADS)

Optical emission from type-II ZnTe/ZnSe quantum dots demonstrates large and persistent oscillations in both the peak energy and intensity indicating the formation of coherently rotating states. Furthermore, these Aharonov-Bohm oscillations are shown to be remarkably robust and persist until 180 K. This is at least one order of magnitude greater than the typical temperatures in lithographically defined rings. To our knowledge, this is the highest temperature at which the AB effect has been observed in solid-state and molecular nanostructures.

Sellers, I. R.; Whiteside, V. R.; Kuskovsky, I. L.; Govorov, A. O.; McCombe, B. D.

2008-04-01

151

Noncircular semiconductor nanorings of types I and II: Emission kinetics in the excitonic Aharonov-Bohm effect  

NASA Astrophysics Data System (ADS)

Transition energies and oscillator strengths of excitons in dependence on magnetic field are investigated in types I and II semiconductor nanorings. A slight deviation from circular (concentric) shape of the type II nanoring gives a better observability of the Aharonov-Bohm oscillations since the ground state is always optically active. Kinetic equations for the exciton occupation are solved with acoustic phonon scattering as the major relaxation process, and absorption and luminescence spectra are calculated, showing deviations from equilibrium. The presence of a nonradiative exciton decay leads to a quenching of the integrated photoluminescence with magnetic field.

Grochol, Michal; Zimmermann, Roland

2007-11-01

152

Coherent Aharonov-Bohm oscillations in type-II (Zn,Mn)Te/ZnSe quantum dots  

NASA Astrophysics Data System (ADS)

The magneto-photoluminescence of type-II (Zn,Mn)Te quantum dots is presented. As a result of the type-II band alignment, Aharonov-Bohm (AB) oscillations in the photoluminescence intensity are evident. In addition, an interesting interplay between the AB effect and the spin polarization in these diluted magnetic semiconductor quantum dots is observed. The intensity of the AB oscillations increases with both magnetic field and the degree of optical polarization, indicating that the suppression of spin fluctuations improves the coherence of the system.

Sellers, I. R.; Whiteside, V. R.; Govorov, A. O.; Fan, W. C.; Chou, W.-C.; Khan, I.; Petrou, A.; McCombe, B. D.

2008-06-01

153

The Aharonov-Bohm effect with a twist: Electron transport through finite-width Möbius rings  

NASA Astrophysics Data System (ADS)

The Aharonov-Bohm effect manifests itself in the interference of electron waves traveling through multiply-connected regions and the flux linked with the paths for the electron. Here, we consider the transmission of electrons in the presence of a magnetic field through a finite-width Möbius ring structure which displays a nontrivial topology. The results are compared with the transport through a flat annular ring and a cylindrical ring, with finite-width input and output contacts attached at the periphery in order to highlight the differences in the transmission and conductance patterns. We develop a model to account for the main features associated with the interference effects for propagating states on the Möbius ring. We demonstrate that the periodicity in the magnetic flux, in units of h/e, is weakly broken on 2D rings of finite width, so that the simple treatment proposed here is sufficient for interpreting results. The unusual states with half-integer values of ?Lz? present on Möbius rings display a different characteristic in transmission. Such resonant states are in constructive interference for transmission at magnetic fields where the contribution from ordinary states with integer ?Lz? is in destructive interference, and vice versa. This leads to an alternating dominance of the set of half-integer ?Lz? states and the set of integer ?Lz? states in transport with increasing magnetic fields. We calculate the conductance of the rings, using the Landauer-Büttiker formula, as a function of the magnetic field and the applied bias at contact reservoirs. The differences in the structures considered lend hope for possible for magnetic sensor applications.

Li, Zehao; Ram-Mohan, L. R.

2013-10-01

154

High-Velocity Estimates for the Scattering Operator and Aharonov-Bohm Effect in Three Dimensions  

E-print Network

We obtain high-velocity estimates with error bounds for the scattering operator of the Schr\\"odinger equation in three dimensions with electromagnetic potentials in the exterior of bounded obstacles that are handlebodies. A particular case is a finite number of tori. We prove our results with time-dependent methods. We consider high-velocity estimates where the direction of the velocity of the incoming electrons is kept fixed as its absolute value goes to infinity. In the case of one torus our results give a rigorous proof that quantum mechanics predicts the interference patterns observed in the fundamental experiments of Tonomura et al. that gave a conclusive evidence of the existence of the Aharonov-Bohm effect using a toroidal magnet. We give a method for the reconstruction of the flux of the magnetic field over a cross-section of the torus modulo $2\\pi$. Equivalently, we determine modulo $2\\pi$ the difference in phase for two electrons that travel to infinity, when one goes inside the hole and the other outside it. For this purpose we only need the high-velocity limit of the scattering operator for one direction of the velocity of the incoming electrons. When there are several tori -or more generally handlebodies- the information that we obtain in the fluxes, and on the difference of phases, depends on the relative position of the tori and on the direction of the velocities when we take the high-velocity limit of the incoming electrons. For some locations of the tori we can determine all the fluxes modulo 2$\\pi$ by taking the high-velocity limit in only one direction. We also give a method for the unique reconstruction of the electric potential and the magnetic field outside the handlebodies from the high-velocity limit of the scattering operator.

Miguel Ballesteros; Ricardo Weder

2007-11-16

155

Classical Interaction of a Magnet and a Point Charge: The Classical Electromagnetic Forces Responsible for the Aharonov-Bohm Phase Shift  

E-print Network

A new classical electromagnetic analysis is presented suggesting that the Aharonov-Bohm phase shift is overwhelmingly likely to arise from a classical lag effect based upon classical electromagnetic forces. The analysis makes use of several aspects of classical electromagnetic theory which are unfamiliar to most physicists, including the Darwin Lagrangian, acceleration-based electric fields, internal electromagnetic momentum in a magnet, and a magnet model involving at least three mutually-interacting particles. Only when the acceleration-based electric forces acting on the passing charge are included do we find consistency with all the relativistic conservation laws: energy, linear momentum, angular momentum, and constant center-of-mass velocity. The electric forces on the passing charge lead to a lag effect which accounts quantitatively for the Aharonov-Bohm phase shift. Thus the classical analysis strongly suggests that the Aharonov-Bohm phase shift (observed when electrons pass a long solenoid which corresponds to a line of magnetic dipoles) is the analogue of the Matteucci-Pozzi phase shift (observed when electrons pass a line of electric dipoles). The classical electromagnetic analysis suggests experiments to distinguish the proposed classical-based lag effect from the presently accepted view that the Aharonov-Bohm phase shift is a quantum topological effect arising from magnetic fluxes in the absence of classical electromagnetic forces.

Timothy H. Boyer

2014-08-16

156

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Spin Filter Based on an Aharonov Bohm Interferometer with Rashba Spin Orbit Effect  

Microsoft Academic Search

We propose a spin filter based on both the quantum interference and the Rashba spin-orbit (RSO) effects. This spin filter consists of a Aharonov-Bohm (AB) interferometer with two quantum dots (QDs) inserted in its arms. The influences of a magnetic flux varphi threading through the AB ring and the RSO interaction inside the two QDs are taken into account by

Ming Fang; Lian-Liang Sun

2008-01-01

157

Mesoscopic photovoltaic effect in GaAs/Ga1-xAlxAs Aharonov-Bohm rings L. Angers, A. Chepelianskii, R. Deblock, B. Reulet, and H. Bouchiat  

E-print Network

Mesoscopic photovoltaic effect in GaAs/Ga1-xAlxAs Aharonov-Bohm rings L. Angers, A. Chepelianskii specific dc voltage. We have investigated this photovoltaic PV effect on GaAs/Ga1-xAlxAs Aharonov is generally done by measuring the dc induced signal sometimes called photovoltaic effect which has also given

Shepelyansky, Dima

158

Magnetoresistance of nanoscale molecular devices based on Aharonov-Bohm interferometry.  

PubMed

Control of conductance in molecular junctions is of key importance in the growing field of molecular electronics. The current in these junctions is often controlled by an electric gate designed to shift conductance peaks into the low bias regime. Magnetic fields, on the other hand, have rarely been used due to the small magnetic flux captured by molecular conductors (an exception is the Kondo effect in single-molecule transistors). This is in contrast to a related field, electronic transport through mesoscopic devices, where considerable activity with magnetic fields has led to a rich description of transport. The scarcity of experimental activity is due to the belief that significant magnetic response is obtained only when the magnetic flux is of the order of the quantum flux, while attaining such a flux for molecular and nanoscale devices requires unrealistic magnetic fields. Here we review recent theoretical work regarding the essential physical requirements necessary for the construction of nanometer-scale magnetoresistance devices based on an Aharonov-Bohm molecular interferometer. We show that control of the conductance properties using small fractions of a magnetic flux can be achieved by carefully adjusting the lifetime of the conducting electrons through a pre-selected single state that is well separated from other states due to quantum confinement effects. Using a simple analytical model and more elaborate atomistic calculations we demonstrate that magnetic fields which give rise to a magnetic flux comparable to 10(-3) of the quantum flux can be used to switch a class of different molecular and nanometer rings, ranging from quantum corrals, carbon nanotubes and even a molecular ring composed of polyconjugated aromatic materials. The unique characteristics of the magnetic field as a gate is further discussed and demonstrated in two different directions. First, a three-terminal molecular router devices that can function as a parallel logic gate, processing two logic operations simultaneously, is presented. Second, the role of inelastic effects arising from electron-phonon couplings on the magnetoresistance properties is analyzed. We show that a remarkable difference between electric and magnetic gating is also revealed when inelastic effects become significant. The inelastic broadening of response curves to electric gates is replaced by a narrowing of magnetoconductance peaks, thereby enhancing the sensitivity of the device. PMID:21693808

Hod, Oded; Baer, Roi; Rabani, Eran

2008-09-24

159

Spin-Orbit Effect on the Magneto-Optical Aharonov-Bohm Spectrum of Exciton in Semiconductor Quantum Rings  

NASA Astrophysics Data System (ADS)

We investigate the Rashba spin-orbit interaction (RSOI) and Dresselhaus spin-orbit interaction (DSOI) on exciton spectrum in a semiconductor double-ring threaded by a perpendicular magnetic flux. Compared with many-electron systems, the multi-zigzag Aharonov-Bohm spectrum of exciton is even richer under the interplay between spin-orbit, Zeeman, and Coulomb effects. We also calculate the optical absorption strength to demonstrate the complex optical transitions in the presence of SOIs. The electron-hole separation is another quantity of interest. Via control of RSOI and DSOI strengths, we can manipulate the population of electron and hole in the double-ring. As a consequence, the adjustment is directly concerned with the generation of charge currents and spin currents, which can be applied to achieve the opportunity of quantum control.

Kuan, Wen-Hsuan

2012-02-01

160

Shot noise in a double-quantum-dot Aharonov-Bohm interferometer under the perturbation of ac fields  

NASA Astrophysics Data System (ADS)

We have investigated the shot noise spectral density in the parallel double-quantum-dot (DQD) interferometer threaded with an Aharonov-Bohm (AB) flux under the perturbation of ac fields. The derivations are based on the nonequilibrium Green's function (NGF) technique in the Coulomb blockade regime. The AB flux and the perturbation of ac fields together provide a photon-assisted AB interferometer for controlling the shot noise efficiently. The signature of the shot noise reflects the intrinsic microstructure of the DQD system, which plays important roles for the enhancement and suppression of shot noise. The versatile resonant structures of shot noise, Fano factor have been revealed to exhibit the sub-Poissonian and super-Poissonian types of shot noise by adjusting the gate voltages sequentially.

Zhao, H.-K.; Zhao, L.-L.

2011-02-01

161

Quantum geometric phase in Majorana's stellar representation: mapping onto a many-body Aharonov-Bohm phase.  

PubMed

The (Berry-Aharonov-Anandan) geometric phase acquired during a cyclic quantum evolution of finite-dimensional quantum systems is studied. It is shown that a pure quantum state in a (2J+1)-dimensional Hilbert space (or, equivalently, of a spin-J system) can be mapped onto the partition function of a gas of independent Dirac strings moving on a sphere and subject to the Coulomb repulsion of 2J fixed test charges (the Majorana stars) characterizing the quantum state. The geometric phase may be viewed as the Aharonov-Bohm phase acquired by the Majorana stars as they move through the gas of Dirac strings. Expressions for the geometric connection and curvature, for the metric tensor, as well as for the multipole moments (dipole, quadrupole, etc.), are given in terms of the Majorana stars. Finally, the geometric formulation of the quantum dynamics is presented and its application to systems with exotic ordering such as spin nematics is outlined. PMID:23004240

Bruno, Patrick

2012-06-15

162

The double slit experiment, the Aharonov-Bohm effect, and a new quantum potential theory: Towards a realistic interpretation of quantum mechanics  

NASA Astrophysics Data System (ADS)

In this paper, a new proposal of the quantum potential theory is presented, along with a discussion of the two-slit interference experiment and the Aharonov-Bohm effect, which are explicitly calculated within the scheme adopted. The present formulation holds the notion of particle trajectory and follows the interpretation suggested by de Broglie and Bohm, the quantum potential being a manifestation of the quantum wave. This wave always satisfies the Schrödinger equation and is considered as a real and separate entity from the particle with which is associated. In our approach we try to circumvent some conceptual difficulties that prevent the de Broglie-Bohm's theory from fulfilling a complete objective program. New effects are predicted, specially for the Aharonov-Bohm experiment in the regime of high magnetic fields, and a setup for their detection is proposed.

Mónaco, R. E. L.; Cabrera, G. G.

1994-02-01

163

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Anomalous Kondo-Switching Effect of a Spin-Flip Quantum Dot Embedded in an Aharonov-Bohm Ring  

Microsoft Academic Search

We theoretically investigate the Kondo effect of a quantum dot embedded in a mesoscopic Aharonov-Bohm (AB) ring in the presence of the spin flip processes by means of the one-impurity Anderson Hamiltonian. Based on the slave-boson mean-field theory, we find that in this system the persistent current (PC) sensitively depends on the parity and size of the AB ring and

Xiong-Wen Chen; Zhen-Gang Shi; Ke-Hui Song

2009-01-01

164

Modulation of the Aharonov Bohm effect in type-II II V ZnSe:Te quantum dots by a far-infrared laser  

Microsoft Academic Search

We present magneto-photoluminescence of a ZnTe\\/ZnSe multilayer structure in which the clustering of Te atoms results in the formation of columns of type-II ZnSe:Te quantum dots. This unique geometry permits the observation of strong Aharonov Bohm oscillations in both the emission energy and peak intensity with increasing magnetic field. Furthermore, far-infrared optically detected resonance techniques exhibit resonances that are ascribed

Ian R. Sellers; Vincent R. Whiteside; Igor L. Kuskovsky; Alexander O. Govorov; Bruce D. McCombe

2008-01-01

165

Edge states, Aharonov-Bohm oscillations, and thermodynamic and spectral properties in a two-dimensional electron gas with an antidot  

SciTech Connect

The thermodynamic and spectral properties of a two-dimensional electron gas with an antidot in a strong magnetic field, {ital r}{sub {ital c}}{le}{ital r}{sub 0}, where {ital r}{sub {ital c}} is the cyclotron radius and {ital r}{sub 0} is the antidot effective radius, are studied via a solvable model with the antidot confinement potential {ital U}{similar_to}1/{ital r}{sup 2}. The edge states localized at the antidot boundary result in an Aharonov-Bohm-type oscillatory dependence of the magnetization as a function of the magnetic field flux through the antidot. These oscillations are superimposed on the de Haas--van Alphen oscillations. In the strong-field limit, {h_bar}{omega}{sub {ital c}}{similar_to}{epsilon}{sub {ital F}}, where {omega}{sub {ital c}} is the cyclotron frequency and {epsilon}{sub {ital F}} is the Fermi energy, the amplitude of the Aharonov-Bohm-type oscillations of the magnetization due to the contribution of the lowest edge state is {similar_to}{mu}{sub {ital B}}{ital k}{sub {ital F}}{ital r}{sub {ital c}} ({mu}{sub {ital B}} is the Bohr magneton and {ital k}{sub {ital F}} is the Fermi wave vector). When the magnetic field is decreased, higher edge states can contribute to the magnetization, leading to the appearance of a beating pattern in the Aharonov-Bohm oscillations. The role of temperature in suppressing the oscillatory contribution due to higher edge states is analyzed. Rapid oscillations of the magnetization as a function of the Aharonov-Bohm flux, occurring on a scale of a small fraction of the flux quantum {ital hc}/{ital e}, are demonstrated. The appearance of a manifold of non- equidistant frequencies in the magneto-optical-absorption spectrum, due to transitions between electronic edge states localized near the antidot boundary, is predicted.

Bogachek, E.N.; Landman, U. [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)] [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

1995-11-15

166

Modulation of the Aharonov–Bohm effect in type-II II–V ZnSe:Te quantum dots by a far-infrared laser  

Microsoft Academic Search

We present magneto-photoluminescence of a ZnTe\\/ZnSe multilayer structure in which the clustering of Te atoms results in the formation of columns of type-II ZnSe:Te quantum dots. This unique geometry permits the observation of strong Aharonov–Bohm oscillations in both the emission energy and peak intensity with increasing magnetic field. Furthermore, far-infrared optically detected resonance techniques exhibit resonances that are ascribed to

Ian R. Sellers; Vincent R. Whiteside; Igor L. Kuskovsky; Alexander O. Govorov; Bruce D. McCombe

2008-01-01

167

Edge states, Aharonov-Bohm oscillations, and thermodynamic and spectral properties in a two-dimensional electron gas with an antidot  

Microsoft Academic Search

The thermodynamic and spectral properties of a two-dimensional electron gas with an antidot in a strong magnetic field, rc<=r0, where rc is the cyclotron radius and r0 is the antidot effective radius, are studied via a solvable model with the antidot confinement potential U~1\\/r2. The edge states localized at the antidot boundary result in an Aharonov-Bohm-type oscillatory dependence of the

E. N. Bogachek; Uzi Landman

1995-01-01

168

The optical Aharonov-Bohm effect and magneto-optical properties in type-II quantum dots  

NASA Astrophysics Data System (ADS)

We present a detailed experimental study of the magneto-optical properties of type-II quantum dots (QDs) in: (1) ZnTe/ZnSe superlattices grown by Molecular Beam Epitaxy (MBE)---these Zn(SeTe) QDs evolve from Te-clustering in the ZnSe matrix during growth; and (2) diluted magnetic semiconductor, (ZnMn)Se, QDs in a ZnSe matrix produced by migration enhanced epitaxy. In case (1) the Zn(SeTe) QDs display large and robust (with temperature) oscillations as a function of magnetic field in both the photoluminescence energy and intensity as a result of the optical Aharonov-Bohm effect. The large strength of these oscillations is attributed to a combination of the type-II symmetry and the columnar geometry of the structures; the oscillations persist until 180K. The type-II diluted magnetic semiconductor, (ZnMn)Te quantum dots display similar oscillatory effects in the emission intensity. Interestingly, the coherence of the Aharonov-Bohm phase in these magnetic dots is strongly related to the spin polarization of the system due to the Mn-exciton exchange interaction as shown by the disappearance of the oscillations at low magnetic fields. The enhanced coherence at high fields, which leads to strong oscillations in intensity, is attributed to removal of magnetic disorder by the applied magnetic field. While the magnetic nature of the QDs is clear from the polarization measurements there is the seemingly contradictory behavior of a very small Zeeman shift for material that has a corresponding large Zeeman shift for the comparable composition of bulk (ZnMn)Te. More importantly, a red shift greater than 30 meV is observed in the peak energy of the PL as function of time after excitation with a picosecond pulse. These results can be explained by postulating formation of bound magnetic polarons in the QDs. The overall red shift is identified as the magnetic polaron binding energy, EMP; it is roughly independent of temperature, persisting up to 150K. The large MP binding energy is apparently contradictory to the small observed Zeeman splitting and the temperature dependence of the optical polarization in the steady state. These apparently contradictory properties are interpreted in terms of a model that explains the temperature dependence as well as the polarization and Zeeman energy splitting, while fully taking into account the polaron formation energy. The model is based on the hole-Mn and the Mn-Mn exchange coupling and their role in the magnetic polaron formation with a crucial aspect being the formation of an antiferromagnetically ordered state of the Mn spin system in each of the QDs in the absence of photoinjected holes.

Whiteside, Vincent Ryan

169

Modulation of the Aharonov Bohm effect in type-II II V ZnSe:Te quantum dots by a far-infrared laser  

NASA Astrophysics Data System (ADS)

We present magneto-photoluminescence of a ZnTe/ZnSe multilayer structure in which the clustering of Te atoms results in the formation of columns of type-II ZnSe:Te quantum dots. This unique geometry permits the observation of strong Aharonov-Bohm oscillations in both the emission energy and peak intensity with increasing magnetic field. Furthermore, far-infrared optically detected resonance techniques exhibit resonances that are ascribed to the activation and recapture of electrons by different subsets of quantum dots.

Sellers, Ian R.; Whiteside, Vincent R.; Kuskovsky, Igor L.; Govorov, Alexander O.; McCombe, Bruce D.

2008-04-01

170

Determination of excitonic size with sub-nanometer precision via excitonic Aharonov-Bohm effect in type-II quantum dots  

NASA Astrophysics Data System (ADS)

A spectral analysis of the Aharonov-Bohm (AB) oscillation in magneto-photoluminescence intensity was performed for stacked type-II ZnTe/ZnSe quantum dots (QDs). Very narrow AB oscillations (˜0.3 T) allowed for probing of both the lateral size distribution in the stack ensemble of QDs and the size of type-II excitons as determined by the electronic orbit with sub-nanometer precision. Two sets of stacks with excitonic size of 18.2 and 17.5 nm are determined to be present in the sample.

Roy, B.; Ji, H.; Dhomkar, S.; Cadieu, F. J.; Peng, L.; Moug, R.; Tamargo, M. C.; Kuskovsky, I. L.

2012-05-01

171

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Anomalous Kondo-Switching Effect of a Spin-Flip Quantum Dot Embedded in an Aharonov-Bohm Ring  

NASA Astrophysics Data System (ADS)

We theoretically investigate the Kondo effect of a quantum dot embedded in a mesoscopic Aharonov-Bohm (AB) ring in the presence of the spin flip processes by means of the one-impurity Anderson Hamiltonian. Based on the slave-boson mean-field theory, we find that in this system the persistent current (PC) sensitively depends on the parity and size of the AB ring and can be tuned by the spin-flip scattering (R). In the small AB ring, the PC is suppressed due to the enhancing R weakening the Kondo resonance. On the contrary, in the large AB ring, with R increasing, the peak of PC firstly moves up to max-peak and then down. Especially, the PC phase shift of ? appears suddenly with the proper value of R, implying the existence of the anomalous Kondo effect in this system. Thus this system may be a candidate for quantum switch.

Chen, Xiong-Wen; Shi, Zhen-Gang; Song, Ke-Hui

2009-11-01

172

Aharonov-Bohm Effect  

NSDL National Science Digital Library

This web page illustrates the effect of a magnetic flux on the interference of a quantum double-slit experiment. The time-dependent scattering patterns are shown with and without a magnetic field. In addition, the effects of changing the topology of the system are discussed and displayed.

Michielsen, Kristel; De Raedt, Hans

2004-03-10

173

Optical Aharonov-Bohm Effect in Al0.08Ga0.92As/Al.25Ga0.75As Quantum Wells  

NASA Astrophysics Data System (ADS)

The photoluminescence (PL) from Al0.08Ga0.92As/Al.25Ga0.75As quantum wells (QW) was studied as function of magnetic field applied along the normal to the QW planes. The PL intensity exhibits two maxima at 2.3 and 4.9 tesla. The time-resolved PL from the same sample has a decay time which is one order of magnitude longer than the PL from a GaAs/AlGaAs QW, indicating that the recombination in the AlGaAs QW is spatially indirect. The PL intensity oscillations are attributed to the optical Aharonov-Bohm effect associated with spatially quasi-indirect excitons, which are located in the vicinity of islands with lower Al composition. The holes are localized by the islands, while the electrons move around them in a ring-like geometry. This model is in agreement with the interpretation of earlier results from AlxGa1-xAs/AlyGa1-yAs Fe spin-LEDs.

Russ, Andreas; Schweidenback, Lars; Murphy, Joseph; Cartwright, Alexander; Petrou, Athos; Kioseoglou, George; Govorov, Alexander; Hanbicki, Aubrey; Jonker, Berend

2012-02-01

174

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Spin Filter Based on an Aharonov Bohm Interferometer with Rashba Spin Orbit Effect  

NASA Astrophysics Data System (ADS)

We propose a spin filter based on both the quantum interference and the Rashba spin-orbit (RSO) effects. This spin filter consists of a Aharonov-Bohm (AB) interferometer with two quantum dots (QDs) inserted in its arms. The influences of a magnetic flux varphi threading through the AB ring and the RSO interaction inside the two QDs are taken into account by using the nonequilibrium Green's function technique. Due to the existence of the RSO interaction, the electrons flowing through different arms of the ring will acquire a spin-dependent phase factor in the linewidth matrix elements. This phase factor, combined with the influence of the magnetic flux, will induce a spin-dependent electron transport through the device. Moreover, we show that by tuning the magnetic flux, the RSO strength and the inter-dot tunnelling coupling strength, a pure spin-up or spin-down conductance can be obtained when a spin-unpolarized current is injected from the external leads, which can be used to filter the electron spin.

Fang, Ming; Sun, Lian-Liang

2008-09-01

175

Tunable spin-dependent Andreev reflection in a four-terminal Aharonov-Bohm interferometer with coherent indirect coupling and Rashba spin-orbit interaction  

PubMed Central

Using the nonequilibrium Green’s function method, we theoretically study the Andreev reflection(AR) in a four-terminal Aharonov-Bohm interferometer containing a coupled double quantum dot with the Rashba spin-orbit interaction (RSOI) and the coherent indirect coupling via two ferromagnetic leads. When two ferromagnetic electrodes are in the parallel configuration, the spin-up conductance is equal to the spin-down conductance due to the absence of the RSOI. However, for the antiparallel alignment, the spin-polarized AR occurs resulting from the crossed AR (CAR) and the RSOI. The effects of the coherent indirect coupling, RSOI, and magnetic flux on the Andreev-reflected tunneling magnetoresistance are analyzed at length. The spin-related current is calculated, and a distinct swap effect emerges. Furthermore, the pure spin current can be generated due to the CAR when two ferromagnets become two half metals. It is found that the strong RSOI and the large indirect coupling are in favor of the CAR and the production of the strong spin current. The properties of the spin-related current are tunable in terms of the external parameters. Our results offer new ways to manipulate the spin-dependent transport. PMID:23228047

2012-01-01

176

Real-time dynamics of spin-dependent transport through a double-quantum-dot Aharonov-Bohm interferometer with spin-orbit interaction  

NASA Astrophysics Data System (ADS)

The spin-resolved nonequilibrium real-time electron transport through a double-quantum-dot (DQD) Aharonov-Bohm (AB) interferometer with spin-orbit interaction (SOI) is explored. The SOI and AB interference in the real-time dynamics of spin transport is expressed by effective magnetic fluxes. Analytical formulas for the time-dependent currents, for initially unpolarized spins, are presented. In many cases, there appear spin currents in the electrodes, for which the spins in each electrode are polarized along characteristic directions, predetermined by the SOI parameters and by the geometry of the system. Special choices of the system parameters yield steady-state currents in which the spins are fully polarized along these characteristic directions. The time required to reach this steady state depends on the couplings of the DQD to the leads. The magnitudes of the currents depend strongly on the SOI-induced effective fluxes. Without the magnetic flux, the spin-polarized current cannot be sustained to the steady states, due to the phase rigidity for this system. For a nondegenerate DQD, transient spin transport can be produced by the sole effects of SOI. We also show that one can extract the spin-resolved currents from measurements of the total charge current.

Tu, Matisse Wei-Yuan; Aharony, Amnon; Zhang, Wei-Min; Entin-Wohlman, Ora

2014-10-01

177

Tunable spin-dependent Andreev reflection in a four-terminal Aharonov-Bohm interferometer with coherent indirect coupling and Rashba spin-orbit interaction  

NASA Astrophysics Data System (ADS)

Using the nonequilibrium Green's function method, we theoretically study the Andreev reflection(AR) in a four-terminal Aharonov-Bohm interferometer containing a coupled double quantum dot with the Rashba spin-orbit interaction (RSOI) and the coherent indirect coupling via two ferromagnetic leads. When two ferromagnetic electrodes are in the parallel configuration, the spin-up conductance is equal to the spin-down conductance due to the absence of the RSOI. However, for the antiparallel alignment, the spin-polarized AR occurs resulting from the crossed AR (CAR) and the RSOI. The effects of the coherent indirect coupling, RSOI, and magnetic flux on the Andreev-reflected tunneling magnetoresistance are analyzed at length. The spin-related current is calculated, and a distinct swap effect emerges. Furthermore, the pure spin current can be generated due to the CAR when two ferromagnets become two half metals. It is found that the strong RSOI and the large indirect coupling are in favor of the CAR and the production of the strong spin current. The properties of the spin-related current are tunable in terms of the external parameters. Our results offer new ways to manipulate the spin-dependent transport.

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

2012-12-01

178

Novel Aharonov-Bohm-like effect: Detectability of the vector potential in a solenoidal configuration with a ferromagnetic core covered by superconducting lead, and surrounded by a thin cylindrical shell of aluminum  

E-print Network

The flux as measured by the Josephson effect in a SQUID-like configuration with a ferromagnetic core inserted into its center, is shown to be sensitive to the vector potential arising from the central ferromagnetic core, even when the core is covered with a superconducting material that prevents any magnetic field lines from ever reaching the perimeter of the SQUID-like configuration. This leads to a macroscopic, Aharonov-Bohm-like effect that is observable in an asymmetric hysteresis loop in the response of the SQUID-like configuration to an externally applied magnetic field.

R. Y. Chiao

2012-06-23

179

CALL FOR PAPERS: Special issue on Quantum Phases: 50 Years of the Aharonov-Bohm Effect and 25 Years of the Berry Phase Special issue on Quantum Phases: 50 Years of the Aharonov-Bohm Effect and 25 Years of the Berry Phase  

NASA Astrophysics Data System (ADS)

This is a call for contributions to a special issue of Journal of Physics A: Mathematical and Theoretical dedicated to the subject of quantum phases and highlighting the impact of the discovery of the Aharonov--Bohm effect and of the Berry phase across physics. Researchers working in the area are invited to submit papers of original research to this issue. Editorial policy The Editorial Board has invited Lev Vaidman, Mark Dennis and Sandu Popescu to serve as Guest Editors for the special issue. The criteria for acceptance of contributions are as follows: Contributions will be refereed and processed according to the usual procedure and high standards of the journal. Papers should be original and should contain substantial new results. All contributions will be refereed and processed according to the usual procedure of the journal. Papers should report original and significant research that has not already been published. Guidelines for preparation of contributions The DEADLINE for contributed papers will be 1 February 2010. This deadline will allow the special issue to appear in September 2010. Advice on publishing your work in Journal of Physics A: Mathematical and Theoretical www.iop.org/Journals/jphysa. Contributions to the special issue should be submitted electronically, if possible, by web upload at www.iop.org/Journals/jphysa, or by email to jphysa@iop.org, quoting 'JPhysA Special Issue— Quantum Phases'. Submissions should ideally be in standard LaTeX form. Please see the website for further information on electronic submissions. Authors unable to submit electronically may send hard-copy contributions to: Publishing Administrators, Journal of Physics A, IOP Publishing, Dirac House, Temple Back, Bristol BS1 6BE, UK. Please quote 'JPhysA Special Issue— Quantum Phases'. All contributions should be accompanied by a read-me file or covering letter giving the postal and e-mail addresses for correspondence. The Publishing Office should be notified of any subsequent change of address. This special issue will be published in the paper and online version of the journal.

Vaidman, Lev; Dennis, Mark; Popescu, Sandu

2010-01-01

180

Aharonov-Bohm effect in optical activity  

Microsoft Academic Search

Optically active media have the helical and dissymmetric crystal structure, which constrains the motions of the electrons to a helical path under the influence of the incident electric field. The charge flow along the helices induces a magnetic field in the direction of the axis of helices. The helical structure hence acts as natural micro-solenoids for the electromagnetic waves passing

C. Z. Tan

2010-01-01

181

Aharonov–Bohm effect in optical activity  

Microsoft Academic Search

Optically active media have the helical and dissymmetric crystal structure, which constrains the motions of the electrons to a helical path under the influence of the incident electric field. The charge flow along the helices induces a magnetic field in the direction of the axis of helices. The helical structure hence acts as natural micro-solenoids for the electromagnetic waves passing

C Z Tan

2010-01-01

182

Aharonov-Bohm effect in carbon nanotubes  

Microsoft Academic Search

Optical absorption spectra are calculated in carbon nanotubes in the presence of a magnetic flux parallel to the tube axis. A drastic change in the band gap manifests itself in optical spectra for light polarization parallel to the axis. In the case of perpendicular polarization, the absorption is suppressed by a large depolarization effect.

Hiroshi Ajiki; Tsuneya Ando

1994-01-01

183

Optical theorem for Aharonov-Bohm scattering  

E-print Network

Quantum-mechanical scattering off an impermeable magnetic vortex is considered and the optical theorem is derived. The nonvanishing transverse size of the vortex is taken into account, and the Robin boundary condition is imposed on the particle wave function at the edge of the vortex. The persistence of the Fraunhofer diffraction in the short-wavelength limit is shown to be crucial for maintaining the optical theorem in the quasiclassical limit.

Sitenko, Yu A

2011-01-01

184

Field Asymmetry of mesoscopic rectification In Aharonov Bohm Rings  

E-print Network

= eVG e FEE µ )( +eV= e EGI F Mesoscopic rectification: Sensitivity of Conductance fluctuations between 2 reservoirs No gate... Semi diffusive regime L > le >W Measurement of non linear transport from by electric pulses and successive illuminations Already experiments in gated structures: Quantum dots g~1

Fominov, Yakov

185

Optical analog of the Aharonov-Bohm interferometer  

Microsoft Academic Search

The problem of the spin dynamics is one of the most interesting in mesoscopic physics. The investigations in this field are stimulated by the possibility of creation of nanodevices, where the spins of the single particles could be precisely manipulated and controlled. The first de- vice of this type, namely spin transistor, was proposed in early 90's in the pioneer

I. A. Shelykh; G. Pavlovic; D. D. Solnyshkov; G. Malpuech

186

Aharonov-Bohm effect of excitons in nanorings  

Microsoft Academic Search

The magnetic field effects on excitons in an InAs nanoring are studied theoretically. By numerically diagonalizing the effective-mass Hamiltonian of the problem that can be separated into terms in center-of-mass and relative coordinates, we calculate the low-lying excitonic energy levels and oscillator strengths as a function of the ring width and the strength of an external magnetic field. It is

Hui Hu; Jia-Lin Zhu; Dai-Jun Li; Jia-Jiong Xiong

2001-01-01

187

Fizeau`s experiment and the Aharonov--Bohm effect  

Microsoft Academic Search

The electromagnetic wave equations in a moving medium may be approximated by a form similar to that of the Schroedinger equation for a particle in an electromagnetic field, with the velocity {bold v} of the medium and the vorticity âÃ{bold v} playing the roles of the vector potential and magnetic field, re- spectively. A purely classical optical analogue of the

Richard J. Cook; H. Fearn; P. W. Milonni

1995-01-01

188

Aharonov–Bohm effect induced by light in a fiber  

Microsoft Academic Search

A weakly coupled normal-metal ring surrounding an optical fiber is considered under the condition that the frequency of light in fiber is larger than the conduction bandwidth of the metal. It is shown that in the presence of static magnetic field parallel to the fiber axis, the resistance of the ring is a nonmonotone function of the optical intensity and

Igor O. Kulik; Alexander S. Shumovsky

1996-01-01

189

Detecting noncommutative phase space by the Aharonov-Bohm effect  

NASA Astrophysics Data System (ADS)

Noncommutative phase space plays an essential role in particle physics and quantum gravity at the Planck scale. However, direct experimental evidence or observation to demonstrate the existence of noncommutative phase space is still lacking. We study a quantum ring in noncommutative phase space based on the Seiberg-Witten map and give the effective magnetic potential and field coming from the noncommutative phase space, which induces the persistent current in the ring. We introduce two variables as two signatures to detect the noncommutative phase space and propose an experimental scheme to detect the noncommutative phase space as long as we measure the persistent current and the external magnetic flux.

Liang, Shi-Dong; Li, Haoqi; Huang, Guang-Yao

2014-07-01

190

Induced Current and Aharonov-Bohm Effect in Graphene  

E-print Network

The effect of vacuum polarization in the field of an infinitesimally thin solenoid at distances much larger than the radius of solenoid is investigated. The induced charge density and induced current are calculated. Though the induced charge density turned out to be zero, the induced current is finite periodical function of the magnetic flux $\\Phi$. The expression for this function is found exactly in a value of the flux. The induced current is equal to zero at the integer values of $\\Phi/\\Phi_0$ as well as at half-integer values of this ratio, where $\\Phi_0=2\\pi\\hbar c/e$ is the elementary magnetic flux. The latter is a consequence of the Furry theorem and periodicity of the induced current with respect to magnetic flux. As an example we consider the graphene in the field of solenoid perpendicular to the plane of a sample.

Jackiw, R; Pi, S -Y; Terekhov, I S

2009-01-01

191

Induced Current and Aharonov-Bohm Effect in Graphene  

E-print Network

The effect of vacuum polarization in the field of an infinitesimally thin solenoid at distances much larger than the radius of solenoid is investigated. The induced charge density and induced current are calculated. Though the induced charge density turned out to be zero, the induced current is finite periodical function of the magnetic flux $\\Phi$. The expression for this function is found exactly in a value of the flux. The induced current is equal to zero at the integer values of $\\Phi/\\Phi_0$ as well as at half-integer values of this ratio, where $\\Phi_0=2\\pi\\hbar c/e$ is the elementary magnetic flux. The latter is a consequence of the Furry theorem and periodicity of the induced current with respect to magnetic flux. As an example we consider the graphene in the field of solenoid perpendicular to the plane of a sample.

R. Jackiw; A. I. Milstein; S. -Y. Pi; I. S. Terekhov

2009-04-14

192

The Aharonov-Bohm effect for an exciton  

NASA Astrophysics Data System (ADS)

We study theoretically the exciton absorption (luminescence) of a ring-like quantum dot shreded by a magnetic flux. We consider the limit when the width of the ring is smaller than the excitonic Bohr radius a_B. We demonstrate that, despite the electrical neutrality of the exciton, both the spectral position of the exciton peak in the absorption (luminescence), and the corresponding oscillator strength oscillate with magnetic flux with a period ?0 --- the universal flux quantum. Assuming that the attraction between electron and hole is short-ranged we find analytically the functional form of these oscillations for both quantities.^1 This enables us to trace the magnitude of the effect with changing the ratio 2 ? R/aB where R is the radius of the ring. Physically, the origin of the oscillations is the finite probability for electron and hole, created by a photon at the same point, to tunnel in the opposite directions and meet each other on the opposite side of the ring. Possible candidates for the experimental observation of the effect are recently discovered self-assembled quantum ring-like structures of InAs embedded in GaAs.^2,3 ^1R.A. Römer and M.E. Raikh, preprint cond-mat/9906314. ^2A. Lorke et al., Microelectronic Engeneering 47, 95 (1999). ^3H. Petterson et al., Proceedings of EP2DS-13, to be published in Physica E, (1999).

Römer, R. A.; Raikh, M. E.

2000-03-01

193

The Aharonov-Bohm effect in conical space  

E-print Network

Conical space emerges inevitably as an outer space of any topological defect of the vortex type. Quantum-mechanical scattering of a nonrelativistic particle by a vortex centred in conical space is considered, and effects of the transverse size of the vortex are taken into account. Paradoxical peculiarities of scattering in the short-wavelength limit are discussed.

Sitenko, Yu A

2010-01-01

194

Optical Aharonov-Bohm effect on Wigner molecules in type-II semiconductor quantum dots  

Microsoft Academic Search

We theoretically examine the magnetoluminescence from a trion and a biexciton in a type-II semiconductor quantum dot, in which holes are confined inside the quantum dot and electrons are in a ring-shaped region surrounding the quantum dot. First, we show that two electrons in the trion and biexciton are strongly correlated to each other, forming a Wigner molecule: Since the

Rin Okuyama; Mikio Eto; Hiroyuki Hyuga

2011-01-01

195

Optical Aharonov-Bohm Effect for type-II InAs Quantum Dots  

Microsoft Academic Search

The magnetic field dependence of the ground- and excited-state transitions in InAs quantum dots (QD), capped with a strain reducing layer of GaAs0.76Sb0.26, which results in a type-II band alignment, has been studied by magneto-photoluminescence (magneto-PL) spectroscopy. Oscillations in the PL intensity of both the excited state and ground state magneto-PL are observed. Similar oscillations in intensity have been previously

Vincent R. Whiteside; Ian R. Sellers; Bruce D. McCombe; Huiyun Liu

2009-01-01

196

Classical light analogue of the non-local Aharonov-Bohm effect  

Microsoft Academic Search

We demonstrate the existence of a non-local geometric phase in the intensity-intensity correlations of classical incoherent light, that is not seen in the lower-order correlations. This two-photon Pancharatnam phase was observed and modulated in a Mach-Zehnder interferometer. Using acousto-optic interaction, independent phase noise was introduced to light in the two arms of the interferometer to create two independent incoherent classical

Nandan Satapathy; Deepak Pandey; Poonam Mehta; Supurna Sinha; Joseph Samuel; Hema Ramachandran

2012-01-01

197

Verification of the Aharonov-Bohm effect in superconductors by use of a toroidal flux geometry  

SciTech Connect

Predictions made by Aharonov and Bohm concerning the effects of electromagnetic potentials on electrons in field-free regions of space, have been demonstrated in superconductors with the use of the flux produced by a very fine toroidal solenoid. The use of a toroidal geometry sidesteps the objections raised by Roy concerning the use of sources of flux with linear geometries. The use of superconductors excludes the possibility that stray electrons can pass through the flux-filled region of space to produce the observed phenomena.

Walker, I.R.

1986-04-01

198

Tunable optical Aharonov-Bohm effect in a semiconductor quantum ring  

NASA Astrophysics Data System (ADS)

By applying an electric field perpendicular to a semiconductor quantum ring we show that it is possible to modify the single particle wave function between quantum dot (QD)-like and ring-like. The constraints on the geometrical parameters of the quantum ring to realize such a transition are derived. With such a perpendicular electric field we are able to tune the Aharanov-Bohm (AB) effect for both the single particle and for excitons. The tunability is in both the strength of the AB effect as well as in its periodicity. We also investigate the strain induce potential inside the self-assembled quantum ring and the effect of the strain on the AB effect.

Li, Bin; Peeters, F. M.

2011-03-01

199

High-sensitivity rotation sensing with atom interferometers using Aharonov-Bohm effect  

Microsoft Academic Search

In recent years there has been significant activity in research and development of high sensitivity accelerometers and gyroscopes using atom interferometers. In these devices, a fringe shift in the interference of atom de Broglie waves indicates the rotation rate of the interferometer relative to an inertial frame of reference. In both optical and atomic conventional Sagnac interferometers, the resultant phase

2006-01-01

200

Excitons in Carbon Nanotubes Revisited: Dependence on Diameter, Aharonov-Bohm Flux, and Strain  

Microsoft Academic Search

Optical spectra are calculated in semiconducting carbon nanotubes in the presence of magnetic flux and strain within a k{\\\\cdot}p scheme. The exciton absorption energies show an extra logarithmic dependence on the diameter after being scaled by the inverse diameter, coming from that of the enhancement of the band gaps. The exciton binding energy remains almost independent of the extra dependence.

Tsuneya Ando

2004-01-01

201

Impurity effects on the Aharonov-Bohm optical signatures of neutral quantum-ring magnetoexcitons  

Microsoft Academic Search

We study the role of impurity scattering on the photoluminescence (PL) emission of polarized magnetoexcitons. We consider systems where both the electron and hole are confined on a ring structure (quantum rings) as well as on a type-II quantum dot. Despite their neutral character, excitons exhibit strong modulation of energy and oscillator strength in the presence of magnetic fields. Scattering

L. G. G. V. Dias da Silva; S. E. Ulloa; A. O. Govorov

2004-01-01

202

Exciton storage in type-II quantum dots using the optical Aharonov-Bohm effect  

NASA Astrophysics Data System (ADS)

We investigate the bright-to-dark exciton conversion efficiency in type-II quantum dots subject to a perpendicular magnetic field. To this end, we take the exciton storage protocol recently proposed by Simonin and co-workers [Phys. Rev. B 89, 075304 (2014)] and simulate its coherent dynamics. We confirm the storage is efficient in perfectly circular structures subject to weak external electric fields, where adiabatic evolution is dominant. In practice, however, the efficiency rapidly degrades with symmetry lowering. Besides, the use of excited states is likely unfeasible owing to the fast decay rates. We then propose an adaptation of the protocol which does not suffer from these limitations.

Climente, Juan I.; Planelles, Josep

2014-05-01

203

Aharonov-Bohm interference in quantum ring exciton: effects of built-in electric fields  

Microsoft Academic Search

We report a comprehensive discussion of quantum interference effects due to\\u000athe finite structure of excitons in quantum rings and their first experimental\\u000acorroboration observed in the optical recombinations. Anomalous features that\\u000aappear in the experiments are analyzed according to theoretical models that\\u000adescribe the modulation of the interference pattern by temperature and built-in\\u000aelectric fields.

M. D. Teodoro; V. L. Campo Jr.; V. Lopez-Richard; E. Marega Jr.; G. E. Marques; Y. Galvao-Gobato; F. Iikawa; M. J. S. P. Brasil; Z. Y. AbuWaar; V. G. Dorogan; Yu. I. Mazur; M. Benamara; G. J. Salamo

2009-01-01

204

Aharonov-Bohm Interference in Neutral Excitons: Effects of Built-In Electric Fields  

NASA Astrophysics Data System (ADS)

We report a comprehensive discussion of quantum interference effects due to the finite structure of neutral excitons in quantum rings and their first experimental corroboration observed in the optical recombinations. The signatures of built-in electric fields and temperature on quantum interference are demonstrated by theoretical models that describe the modulation of the interference pattern and confirmed by complementary experimental procedures.

Teodoro, M. D.; Campo, V. L., Jr.; Lopez-Richard, V.; Marega, E., Jr.; Marques, G. E.; Gobato, Y. Galvão; Iikawa, F.; Brasil, M. J. S. P.; Abuwaar, Z. Y.; Dorogan, V. G.; Mazur, Yu. I.; Benamara, M.; Salamo, G. J.

2010-02-01

205

The Aharonov-Bohm effect and its applications to observations of the microscopic world  

Microsoft Academic Search

Summary  Just as the field of coherent optics was opened up by the advent of the laser beam, coherent electron optics has been propelled\\u000a forward by the development of a field-emission beam which is both bright and monochromatic. This development has made it feasible\\u000a to observe high-contrast electron interference patterns even in real time, thereby making it possible to carry out

A. Tonomura

1995-01-01

206

Excitonic Aharonov-Bohm effect in a two-dimensional quantum ring  

Microsoft Academic Search

We study theoretically the optical properties of an exciton in a two-dimensional ring threaded by a magnetic flux. We model the quantum ring by a confining potential that can be continuously tuned from strictly one-dimensional to truly two-dimensional with finite radius-to-width ratio. We present an analytic solution of the problem when the electron-hole interaction is short ranged. The oscillatory dependence

C. González-Santander; F. Domínguez-Adame; R. A. Römer

2011-01-01

207

Aharonov-Bohm Interference in Neutral Excitons: Effects of Built-In Electric Fields  

Microsoft Academic Search

We report a comprehensive discussion of quantum interference effects due to the finite structure of neutral excitons in quantum rings and their first experimental corroboration observed in the optical recombinations. The signatures of built-in electric fields and temperature on quantum interference are demonstrated by theoretical models that describe the modulation of the interference pattern and confirmed by complementary experimental procedures.

M. D. Teodoro; V. L. Campo Jr.; V. Lopez-Richard; E. Marega Jr.; G. E. Marques; Y. Galvão Gobato; F. Iikawa; M. J. S. P. Brasil; Z. Y. Abuwaar; V. G. Dorogan; Yu. I. Mazur; M. Benamara; G. J. Salamo

2010-01-01

208

Effects of Valley Mixing and Exchange on Excitons in Carbon Nanotubes with Aharonov-Bohm Flux  

Microsoft Academic Search

Because of the presence of two valleys and the electron spin, the exciton states have a degeneracy of 16 in the lowest order k\\\\cdot p approximation. Due to a weak short-range part of the Coulomb interaction, they are split into several levels, leaving only a single optically-active bright level and making all others optically-inactive or dark. Their ordering and energy

Tsuneya Ando

2006-01-01

209

Aharonov-Bohm beam deflection: Shelankov's formula, exact solution, asymptotics and an optical analogue  

Microsoft Academic Search

Using a paraxial analysis, Shelankov (1998 Europhys. Lett. 43 623) has shown that charged particles in a beam of small angular width 1\\/w, aimed at a magnetic flux line with quantum flux icons\\/Journals\\/Common\\/alpha\\

M. V. Berry

1999-01-01

210

Exciton Storage in a Nanoscale Aharonov-Bohm Ring with Electric Field Tuning  

SciTech Connect

We study analytically the optical properties of a simple model for an electron-hole pair on a ring subjected to perpendicular magnetic flux and in-plane electric field. We show how to tune this excitonic system from optically active to optically dark as a function of these external fields. Our results offer a simple mechanism for exciton storage and readout.

Fischer, Andrea M.; Roemer, Rudolf A. [Department of Physics and Centre for Scientific Computing, University of Warwick, Coventry, CV4 7AL (United Kingdom); Campo, Vivaldo L. Jr. [Departmento de Fisica, Universidade Federal de Sao Carlos-UFSCar, 13565-905 Sao Carlos, SP (Brazil); Portnoi, Mikhail E. [School of Physics, University of Exeter, Exeter EX4 4QL (United Kingdom)

2009-03-06

211

Optical properties in a two-dimensional quantum ring: Confinement potential and Aharonov–Bohm effect  

Microsoft Academic Search

Optical properties of a two-dimensional quantum ring with pseudopotential in the presence of an external magnetic field and magnetic flux have been theoretically investigated. Our results show that both of the pseudopotential and magnetic field can affect the third non-linear susceptibility and oscillator strength. In addition, we found that the oscillator strength and the absolute value of the resonant peak

Shijun Liang; Wenfang Xie; Huaya Shen

2011-01-01

212

Slow photons as charged quasi-particles, and photonic Aharonov-Bohm effect  

Microsoft Academic Search

Recently we have proposed the method of Raman Adiabatic Transfer of Optical States (RATOS) to manipulate the optical state of light. A four-level atomic medium in double-lambda configuration is interacting with two pump fields and a signal photon with very slow group velocity. An adiabatic change in time of the pump fields can then generate a slow photon in a

Karl-Peter Marzlin; Juergen Appel; Alexander Lvovsky

2007-01-01

213

Optical Signatures of the Aharonov-Bohm Phase in Single-Walled Carbon Nanotubes  

Microsoft Academic Search

We report interband magneto-optical spectra for single-walled carbon nanotubes in high magnetic fields up to 45 tesla, confirming theoretical predictions that the band structure of a single-walled carbon nanotube is dependent on the magnetic flux phi threading the tube. We have observed field-induced optical anisotropy as well as red shifts and splittings of absorption and photoluminescence peaks. The amounts of

Sasa Zaric; Gordana N. Ostojic; Junichiro Kono; Jonah Shaver; Valerie C. Moore; Michael S. Strano; Robert H. Hauge; Richard E. Smalley; Xing Wei

2004-01-01

214

Tunable optical Aharonov-Bohm effect in a semiconductor quantum ring  

Microsoft Academic Search

By applying an electric field perpendicular to a semiconductor quantum ring we show that it is possible to modify the single particle wave function between quantum dot (QD)-like and ring-like. The constraints on the geometrical parameters of the quantum ring to realize such a transition are derived. With such a perpendicular electric field we are able to tune the Aharanov-Bohm

Bin Li; F. M. Peeters

2011-01-01

215

Scaling of Aharonov-Bohm couplings and the dynamical vacuum in gauge theories  

SciTech Connect

Recent results on the vacuum polarization induced by a thin string of magnetic flux lead us to suggest an analogue of the Copenhagen flux spaghetti'' QCD vacuum as a possible mechanism for avoiding the divergence of perturbative QED, thus permitting a consistent completion of the full, nonperturbative theory. The mechanism appears to operate for spinor, but not scalar, QED.

Goldhaber, A.S. (Intitute for Theoretical Physics, State University of New York, Stony Brook, New York 11794-3840 (United States)); Li, H. (Department of Physics, National Chung-Cheng University, Chia-Yi, Taiwan (Taiwan, Province of China)); Parwani, R.R. (Service de Physique Theorique, CE-Saclay, 91191 Gif-sur-Yvette (France))

1995-01-15

216

Dynamics of a classical Hall system driven by a time-dependent AharonovBohm flux  

E-print Network

: generation, recombina- tion, lifetime, trapping, mean free paths 1 Introduction The motivation to study energy loss. PACS numbers: 45.50.Pk Particle orbits classical mechanics, 45.50.-j Dy- namics1, p2)) in phase space P = R2 \\ (0) Ã? R2 the time dependent Hamiltonian is : 1 2m (p - eA(t, q))2

217

Levinson's theorem and higher degree traces for Aharonov-Bohm operators  

E-print Network

to the scattering operator, the terms at 0-energy and at energy +. The second one is based on non Levinson's theorem. In this context, the Chern number of a bundle defined by a family of projections is put into evidence in a physical context. While the precise physical meaning of this equality deserves

218

Generalised boundary conditions for the Aharonov-Bohm e ect combined with  

E-print Network

, A = A hmf +AAB , with the part A hmf corresponding to the homogeneous magnetic #28;eld in the circular gauge, A hmf = {B 2 ( x 2 dx 1 + x 1 dx 2 ); and with the part AAB corresponding to the idealised AB e#27;ect

219

AZO DYES ARE MAJOR CONTRIBUTORS TO THE MUTAGENIC ACTIVITY DETECTED IN THE CRISTAIS RIVER WATERS  

EPA Science Inventory

To determine if compounds from a dye processing plant were contributing to the mutagenicity repeatedly found in the Cristais River, Sao Paulo, Brazil, we chemically characterized the treated industrial effluent, raw and treated water, and the sludge produced by a Drinking Water T...

220

THE CONTRIBUTION OF AZO DYES TO THE MUTAGENIC ACTIVITY OF THE CRISTAIS RIVER  

EPA Science Inventory

To verify if compounds within the discharge of a dye processing plant were contributing to the mutagenicity repeatedly found in the Cristais River, Sao Paulo, Brazil, we chemically characterized the treated industrial effluent, raw and treated water, and the sludge produced by a ...

221

Aharonov-Bohm Excitons at Elevated Temperatures in Type-II ZnTe\\/ZnSe Quantum Dots  

Microsoft Academic Search

Optical emission from type-II ZnTe\\/ZnSe quantum dots demonstrates large and\\u000apersistent oscillations in both the peak energy and intensity indicating the\\u000aformation of coherently rotating states. Furthermore, the Aharanov-Bohm (AB)\\u000aeffect is shown to be remarkably robust and persists until 180K. This is at\\u000aleast one order of magnitude greater than the typical temperatures in\\u000alithographically defined rings. To our

I. R. Sellers; V. R. Whiteside; I. L. Kuskovsky; A. O. Govorov; B. D. McCombe

2008-01-01

222

Interplay of Aharonov-Bohm, chirality, and aspect ratio effects in the axial conductance of a nanotube  

E-print Network

A magnetic flux applied along the axis of a nanotube can counteract the effect of the tube chirality and dramatically affect its conductance, leading to a way to determine the chirality of a nanotube. The effect of the applied flux is strongest in the long tube limit where the conductance is (i) either a sequence of sharp $4e^{2}/h$ height peaks located at integer (in units of the flux quantum) values of the flux (for an armchair tube) or (ii) a periodic sequence of pairs of $2e^{2}/h$ height peaks for a chiral tube, with the spacing determined by the chirality. In the short tube limit the conductance takes on the value that gives the universal conductivity of an undoped graphene sheet, with a small amplitude modulation periodic in the flux.

Eugene B. Kolomeisky; Joseph P. Straley; Hussain Zaidi

2011-10-03

223

The three-dimensional Dirac-Oscillator in the presence of Aharonov-Bohm and magnetic monopole potentials  

E-print Network

We study the Dirac equation in 3+1 dimensions with non-minimal coupling to isotropic radial three-vector potential and in the presence of static electromagnetic potential. The space component of the electromagnetic potential has angular (non-central) dependence such that the Dirac equation is completely separable in spherical coordinates. We obtain exact solutions for the case where the three-vector potential is linear in the radial coordinate (Dirac-Oscillator) and the time component of the electromagnetic potential vanishes. The relativistic energy spectrum and spinor eigenfunctions are obtained.

A. D. Alhaidari

2005-01-06

224

Temperature dependence of the Aharonov-Bohm oscillations and the energy spectrum in a single-mode ballistic ring  

E-print Network

-mode ballistic ring M. Casse´,1,2 Z. D. Kvon,3 G. M. Gusev,4 E. B. Olshanetskii,1,3 L. V. Litvin,3 A. V oscillations in a single mode ballistic ring has been measured. The experimental data is analyzed using to fab- ricate ballistic ring interferometers.2,3 At low temperatures the electron phase coherence

Gusev, Guennady

225

Electron Vortex Beams in a Magnetic Field: A New Twist on Landau Levels and Aharonov-Bohm States  

E-print Network

as nondiffracting Laguerre-Gaussian beams. Furthermore, the Landau-state beams possess field- and vortex) the Gouy phase, known from optical Laguerre-Gaussian beams. Remarkably, together these phases determine

Nori, Franco

226

THE CASE FOR THE CONTRIBUTION OF CRISTAIS RIVER NITRO-AMINOBENZENE DYES TO THE MUTAGENICITY OF AMBIENT SAMPLES  

EPA Science Inventory

In order to verify if dyestuffs within an effluent of a textile industry was contributing to the systematic mutagenicity detected in the Cristais River, within the metropolitan region of Sao Paulo, mutagenic samples of the industrial effluent, crude water, and treated silt of the...

227

December 12, 2005 13:52 WSPC/Trim Size: 10in x 7in for Proceedings kono-isqm-vf OPTICAL PROCESSES IN SINGLE-WALLED CARBON NANOTUBES  

E-print Network

consistent with existing theories based on the Aharonov-Bohm effect. Keywords: carbon nanotubes; Aharonov-Bohm on the value of /0 where 0 is the magnetic flux quantum. This is a consequence of the Aharonov-Bohm phase 2 on /0. This exotic behavior is a direct consequence of the Aharonov-Bohm (AB) phase influenc- ing

Kono, Junichiro

228

Aharonov-Bohm exciton splitting in the optical absorption of chiral-specific single-walled carbon nanotubes in magnetic fields up to 78 T  

NASA Astrophysics Data System (ADS)

The Ajiki-Ando (A-A) splitting of single-walled carbon nanotubes (SWNTs) originating from the Aharanov-Bohm effect was observed in chiral-specific SWNTs by the magneto-absorption measurements conducted at magnetic fields of up to 78 T. The absorption spectra from each chirality showed clear A-A splitting of the E11 optical excitonic transitions. The parameters of both the dark-bright exciton energy splitting and the rate of A-A splitting in a magnetic field were determined for the first time from the well-resolved absorption spectra.

Takeyama, Shojiro; Suzuki, Hirofumi; Yokoi, Hiroyuki; Murakami, Yoichi; Maruyama, Shigeo

2011-06-01

229

Aharonov-Bohm exciton splitting in the optical absorption of chiral-specific single-walled carbon nanotubes in magnetic fields up to 78 T  

Microsoft Academic Search

The Ajiki-Ando (A-A) splitting of single-walled carbon nanotubes (SWNTs) originating from the Aharanov-Bohm effect was observed in chiral-specific SWNTs by the magneto-absorption measurements conducted at magnetic fields of up to 78 T. The absorption spectra from each chirality showed clear A-A splitting of the E11 optical excitonic transitions. The parameters of both the dark-bright exciton energy splitting and the rate

Shojiro Takeyama; Hirofumi Suzuki; Hiroyuki Yokoi; Yoichi Murakami; Shigeo Maruyama

2011-01-01

230

pss header will be provided by the publisher Magneto-optical spectroscopy of excitons in carbon nanotubes  

E-print Network

Key words : Single-walled carbon nanotubes, Excitons, the Aharonov-Bohm effect. PACS 71.35.Ji, 78: Coulomb- induced splitting; AB: Aharonov-Bohm-induced splitting. Both states become optically degeneracy, and the amount of state splitting is determined by the Aharonov-Bohm phase. We show experimental

Maruyama, Shigeo

231

VOLUME 87, NUMBER 15 P H Y S I C A L R E V I E W L E T T E R S 8 OCTOBER 2001 Kondo Correlations and the Fano Effect in Closed Aharonov-Bohm Interferometers  

E-print Network

observed recently in linear transport through multilevel quantum dots [6], where the nature of the direct effect, and can even be inverted into a Kondo val- ley. We call this behavior the Fano-Kondo effect

232

Magneto-optical spectroscopy of highly aligned carbon nanotubes: Identifying the role of threading magnetic flux  

E-print Network

of 1D magnetoexcitonic bands14,15 based on the Aharonov- Bohm effect.16,21­23 PL measurements were bands with Aharonov-Bohm-phase-dependent energies, masses, and oscillator strengths, successfullyMagneto-optical spectroscopy of highly aligned carbon nanotubes: Identifying the role of threading

Kono, Junichiro

233

Yambo:Yambo: present, past and futurepresent, past and future  

E-print Network

. Chem Phys. 131131, 084102(2009), 084102(2009) #12;Magnetic systems: Ab-initio Aharonov-Bohm effect Anomalous Aharonov-Anomalous Aharonov- Bohm due to theBohm due to the Lorentz correctionLorentz correctionClaudio Attaccalite #12;#12;#12;Nano-structures: Tailoring the optical properties of Si Nws with Si/Ge mixing \\ M

Marini, Andrea

234

Helical Quantum States in HgTe Quantum Dots with Inverted Band Structures Kai Chang and Wen-Kai Lou  

E-print Network

.e., the Aharonov-Bohm effect, can be observed in such a QD structure. This feature offers us a practical way fields, i.e., the Aharonov-Bohm effect. This effect offers us a possibility for detecting these exotic strength of the interband optical transition. This is the common feature for various semiconductor QDs

235

Electronic and transport properties of nanotubes Jean-Christophe Charlier*  

E-print Network

711 D. Quantum interference effects 711 1. Weak localization and the Aharonov-Bohm *Electronic address, will be addressed, including excitonic effects in optical experiments, the Coulomb-blockade regime. Aharonov-Bohm quantum phase 688 2. Parallel field: The band-gap opening and orbital degeneracy splitting

Wu, Zhigang

236

PHYSICAL REVIEW B 84, 075332 (2011) Linear and nonlinear transport in a small charge-tunable open quantum ring  

E-print Network

traveling along different ring arms, the waves acquire a phase shift due to the Aharonov- Bohm (AB) effect Paris, France (Received 18 April 2011; published 16 August 2011) We experimentally study the Aharonov-Bohm-bands).20 Also, the energy spectra were determined by optical spectroscopy in self-assembled rings.21

Gusev, Guennady

237

Magnetic Brightening of Carbon Nanotube Photoluminescence through  

E-print Network

and the interplay of Coulomb interactions and the Aharonov-Bohm effect. This conclusively explains our data to be a consequence of broken time reversal symmetry, working in tandem with the Aharonov-Bohm effect, and has far optical properties dominated by one-dimensional (1-D) excitons with huge binding ener- gies.8 However

Kono, Junichiro

238

Photons as quasicharged particles K.-P. Marzlin, Jrgen Appel, and A. I. Lvovsky  

E-print Network

photons and a topological phase shift of Aharonov-Bohm type. DOI: 10.1103/PhysRevA.77.043813 PACS number around a black hole or generate topological phase fac- tors of the Aharonov-Bohm type 3 , and inhomogeneous dielectric media could generally exhibit geometric effects such as an optical spin-Hall effect

Lvovsky, Alexander

239

Excitons in Carbon Nanotubes with Broken Time-Reversal Symmetry G. N. Ostojic,1  

E-print Network

fields (>55 T). We show that the peak separation is determined by the Aharonov-Bohm phase due to the tube]. This is due to the appearance of the Aharonov-Bohm (AB) phase, 2=0 (where is the tube-threading flux interference effects [6], magneto-optical studies should be able to provide more clear-cut evidence

Kono, Junichiro

240

Optical analog of the Iordanskii force in a Bose-Einstein condensate  

SciTech Connect

A vortex in a Bose-Einstein condensate generates the optical analog of the Aharonov-Bohm effect when illuminated with slow light. In contrast to the original Aharonov-Bohm effect the vortex will exchange forces with the light that leads to a measurable motion of the vortex.

Leonhardt, U.; Oehberg, P. [School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9SS, Scotland (United Kingdom)

2003-05-01

241

RICE UNIVERSITY High Field Magneto-optical Spectroscopy of  

E-print Network

structure and the interplay of Coulomb interactions and the Aharonov-Bohm effect. This conclusively explains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 One-dimensional excitons . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.3 Aharonov-BohmRICE UNIVERSITY High Field Magneto-optical Spectroscopy of Semiconducting Single-walled Carbon

Natelson, Douglas

242

J. Phys. II trance 4 (1994) 1999-2027 NOVEMBER 1994, PAGE 1999 Classification  

E-print Network

experiments of Kasevich and Chu, and the atomic equivalents of the Sagnac and Aharonov-Bohm effects and Chu), a particle in a rotating frame, and the atomic equivalents of the Aharonov-Bohm effects. 1. Path their position and momentum. Also important has been the birth of "atomic optics", a range of mechanisms

Paris-Sud XI, Université de

243

Optical Analog of the Iordanskii Force in a Bose-Einstein Condensate  

Microsoft Academic Search

A vortex in a Bose-Einstein condensate generates the optical analog of the Aharonov-Bohm effect when illuminated with slow light. In contrast to the original Aharonov-Bohm effect the vortex will exchange forces with the light that lead to a measurable motion of the vortex.

U. Leonhardt; P. Ohberg

2001-01-01

244

Optical analog of the Iordanskii force in a Bose-Einstein condensate  

Microsoft Academic Search

A vortex in a Bose-Einstein condensate generates the optical analog of the Aharonov-Bohm effect when illuminated with slow light. In contrast to the original Aharonov-Bohm effect the vortex will exchange forces with the light that leads to a measurable motion of the vortex.

U. Leonhardt; P. Öhberg

2003-01-01

245

Fano effect in a quantum-ringquantum-dot system with tunable coupling A. Fuhrer,1,2 P. Brusheim,1 T. Ihn,2 M. Sigrist,2 K. Ensslin,2 W. Wegscheider,3 and M. Bichler4  

E-print Network

the Fano effect disappears, while the Aharonov-Bohm interference in the ring persists up to T=4.2 K. Good of interacting systems on the other hand. Ring- shaped structures give rise to Aharonov-Bohm AB interference1 of the Fano effect was originally developed for scatter- ing cross sections of nuclei8­10 and in optical

Ihn, Thomas

246

Momentum of electromagnetic fields, speed of light in moving media, and the photon mass  

E-print Network

In both the equations for matter and light wave propagation, the momentum of the electromagnetic fields Pe reflects the relevant em interaction. As a review of some applications of wave propagation properties, an optical experiment which tests the speed of light in moving rarefied gases is described. Moreover, Pe is also the link to the unitary vision of the quantum effects of the Aharonov-Bohm (AB) type, which provide a useful quantum approach for the limit of the photon mass mph. A bench-top experiment based on effects of the AB type that exploit new interferometric techniques, is foreseen to yield the limit mph = 10^-54 g, a value that improves upon the results achieved with other approaches.

Spavieri, Gianfranco

2010-01-01

247

Lecture Notes in Quantum Mechanics Doron Cohen  

E-print Network

, scattering resonances · The Aharonov-Bohm effect · Magnetic field (Landau levels, Hall effect) · Motion · Spherical geometry, phase shifts · Cross section, optical theorem, resonances Quantum mechanics in practice

Cohen, Doron

248

J Low Temp Phys DOI 10.1007/s10909-009-0112-8  

E-print Network

caused by the alignment-- e.g. the shift of optical transitions due to the Aharonov-Bohm effect to the tube axis. SWNTs thus produce a polarization dependent change of the optical transmission, that permits

Natelson, Douglas

249

Gauge invariance and the detection of gravitational radiation  

E-print Network

The detection of gravitational radiation raises some subtle issues having to do with the coordinate invariance of general relativity. This paper explains these issues and their resolution by using an analogy with the Aharonov-Bohm effect of quantum mechanics.

David Garfinkle

2005-11-16

250

Direct Observation of Dark Excitons in Individual Carbon Nanotubes: Inhomogeneity in the Exchange Splitting  

E-print Network

bright excitons due to the Aharonov- Bohm effect [17­19]. Previous temperature (T)-dependent magneto-optical the Aharonov-Bohm effect and intervalley Coulomb mixing. The directly measured dark-bright splitting valuesRevLett.101.087402 PACS numbers: 78.67.Ch, 71.35.Ji, 78.55.�m Optical properties of single-walled carbon

Kono, Junichiro

251

Transport quantique dans les systmes dsordonns Gilles Montambaux, LPS, Orsay  

E-print Network

-electron interactions #12;5 Phase coherence Aharonov-Bohm effect 1 1 b a e A dl = 2 2 i e = 2 2I ( ) 2 2 1 2 1 22 1's law #12;6 Phase coherence Aharonov-Bohm effect 1 1 b a e A dl = 2 2 i e = 2 2I ( ) 2 2 1 2 1 22 1 probability Pcl(r,r',t) Quantum effects : quantum crossings Evaluation of quantum corrections Weak

Paris-Sud 11, Université de

252

Quantum interference in an electron-hole graphene ring system  

SciTech Connect

Quantum interference is observed in a graphene ring system via the Aharonov Bohm effect. As graphene is a gapless semiconductor, this geometry allows to study the unique situation of quantum interference between electrons and holes in addition to the unipolar quantum interference. The period and amplitude of the observed Aharonov-Bohm oscillations are independent of the sign of the applied gate voltage showing the equivalence between unipolar and dipolar interference.

Smirnov, D.; Schmidt, H.; Haug, R. J. [Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstr. 2 30167 Hannover (Germany)

2013-12-04

253

Electromagnetic momentum in frontiers of modern physics  

NASA Astrophysics Data System (ADS)

We review the role of the momentum of the electromagnetic (EM) fields P e in several areas of modern physics. P e represents the EM interaction in equations for matter and light waves propagation. As an application of wave propagation properties, a first order optical experiment which tests the speed of light in moving rarefied gases is presented. Within a classical context, the momentum P e appears also in proposed tests of EM interactions involving open currents and angular momentum conservation laws. Moreover, P e is the link to the unitary vision of the quantum effects of the Aharonov-Bohm (AB) type and, for several of these effects, the strength of P e is evaluated. These effects provide a quantum approach to evaluate the limit of the photon mass m ph. A new effect of the AB type, together with the scalar AB effect, provides the basis for table-top experiments which yield the limit m ph = 9.4 × 10-52g, a value that improves the results achieved with recent classical and quantum approaches.

Spavieri, Gianfranco; Erazo, Jesús; Sanchez, Arturo; Aguirre, Felix; Gillies, George T.; Rodriguez, Miguel

2008-09-01

254

A Note on the Sagnac Effect and Current Terrestrial Experiments  

E-print Network

We focus on the Sagnac effect for light beams in order to evaluate if the higher order relativistic corrections of kinematic origin could be relevant for actual terrestrial experiments. Moreover, we discuss to what extent the analogy with the Aharonov-Bohm effect holds true in a fully relativistic framework. We show that the analogy with the Aharonov-Bohm is not true in general, but is recovered in a suitable low order approximation, and that even though the Sagnac effect is influenced by both the position of the interferometer in the rotating frame and its extension, these effects are negligible for current terrestrial experiments.

Matteo Luca Ruggiero; Angelo Tartaglia

2014-03-25

255

Topological suppression of optical tunneling in a twisted annular fiber  

SciTech Connect

A classical wave-optics analog of topological (Aharonov-Bohm) suppression of tunneling in a double-well potential on a ring threaded by a magnetic flux is proposed. The optical system consists of a uniformly twisted optical fiber with a structured annular core, in which the fiber twist mimics the role of the magnetic flux in the corresponding quantum-mechanical problem. Light waves trapped in the annular core of the fiber experience an additional topological (Aharonov-Bohm) phase, which may lead to the destruction of optical tunneling at certain values of the twist rate.

Ornigotti, M.; Valle, G. Della; Gatti, D.; Longhi, S. [Dipartimento di Fisica and Istituto di Fotonica e Nanotecnologie del CNR, Politecnico di Milano, Piazza L. da Vinci 32, I-20133 Milan (Italy)

2007-08-15

256

Non-local geometric phase in two-photon interferometry , O. Alibart1  

E-print Network

of entanglement between spatially separated quantum channels or systems. A mul- tiparticle Aharonov-Bohm effect or topological PACS 42.50.-p ­ Quantum Optics PACS 42.50.Ar ­ Photon statistics and coherence theory PACS 42 traced out by a pair of single photons. Local measurements at either detector do not reveal the effect

Paris-Sud XI, Université de

257

Asymmetry of localised states in a single quantum ring: polarization dependence of excitons and biexcitons  

E-print Network

symmetry. Currently, quantum ring (QR) structures are of great interest for the optical Aharonov-Bohm (AB) effect [1­ 5]. While the rotating charge in the shell of a type-II quantum dot (QD) determines the AB and 3 nm-thick GaAs for optical measurements. The photo- luminescence (PL) of a single QR was collected

Paris-Sud XI, Université de

258

Large internal dipole moment in InGaN/GaN quantum dots Irina A. Ostapenko, Gerald Hnig, Christian Kindel, Sven Rodt, Andr Strittmatter et al.  

E-print Network

annealing process J. Appl. Phys. 111, 104304 (2012) Spin accumulation in a multi-arm Aharonov-Bohm of nonradiative energy transfer from a quantum well in the optical near field of energy gradient quantum dots Appl. Phys. Lett. 100, 241109 (2012) Refrigeration effect in a single-level quantum dot with thermal bias

Nabben, Reinhard

259

VistasinAstronomy,Vol.37,pp.253-256,1993 PrintedinGreatBritain.Allrightsreserved.  

E-print Network

the region. Quantum mechanics allows inferring the existence of an object in a nonlocal way via Aharonov-Bohm effect even when the object creates no electromagnetic field outside a certain space region, but only-Zehnder interferometer of classical optics. In principle, it can work with any type of particles. A particle reaches

Vaidman, Lev

260

Electronic implementations of interaction-free measurements L. Chirolli,1,* E. Strambini,2 V. Giovannetti,2 F. Taddei,2 V. Piazza,2 R. Fazio,2 F. Beltram,2 and G. Burkard1  

E-print Network

of an asymmetric Aharonov-Bohm ring. For all three cases we show that the presence of a dephasing source acting to optical-IFM setups. The second one consists of a single interferometer and concatenation is achieved as an application of a discrete form of the quantum Zeno effect3 since every step can be considered as a measurement

261

arXiv:1007.3144v1[cond-mat.mes-hall]19Jul2010 Polarization dependence of coherent phonon generation and detection in  

E-print Network

, and with the added properties of the Aharonov-Bohm effect, the elec- tronic band structure of SWNTs respond compare theory with experiment in detail for RBM CPs created by pumping at the E44 optical transition of electrons and phonons results in unique anisotropic electric, magnetic, mechanical, and optical properties.1

Mellor-Crummey, John

262

Sliding charge-density-wave transport in micron-sized wires of Rb0.30MoO3 O. C. Mantel, C. A. W. Bal, C. Langezaal, C. Dekker, and H. S. J. van der Zant  

E-print Network

Aharonov-Bohm-like oscillation of the electrical con- ductance as a function of magnetic flux m and contact spacings down to 1 m, have been patterned into thin films by use of optical phenomena such as narrow-band noise, mode locking on applied ac frequencies, and hyster- esis effects. Many

263

PHYSICAL REVIEW A 81, 032107 (2010) Gauge invariance and reciprocity in quantum mechanics  

E-print Network

with respect to the addition of any scalar potential. In the Aharonov-Bohm effect, reciprocity beyond of reciprocity plays an important role for classical waves in acoustics [1] and optics [2], and for matter waves formulation of the reciprocity principle applied to optics in terms of the Lorentz lemma for electromag- netic

Leung, Pui-Tak "Peter"

264

Unexpected Behavior in a Two-Path Electron Interferometer I. Neder, M. Heiblum, Y. Levinson, D. Mahalu, and V. Umansky  

E-print Network

edge channels in the quantum Hall effect regime, we measured high contrast Aharonov-Bohm (AB- Bohm (AB) effect [10]. Note that the current in D1 is out of phase with respect to the current in D2. Utilizing an electronic analog of the well-known optical Mach-Zehnder interferometer, with current carrying

Heiblum, Mordehai "Moty"

265

Optics and interferometry with atoms and molecules Alexander D. Cronin*  

E-print Network

. Aharonov-Bohm and Aharonov-Casher effects 1089 3. Berry phase 1090 4.Optics and interferometry with atoms and molecules Alexander D. Cronin* Department of Physics waves is a rich branch of atomic physics and quantum optics. It started with atom diffraction from

Cronin, Alex D.

266

IL NUOVO CIMENTO Vol. 114 B, N. 7 Luglio 1999 Feedback-assisted measurement of the free-mass position  

E-print Network

the SQL. PACS 03.65.Bz ­ Foundations, theory of measurement, miscellaneous theories (in- cluding Aharonov-Bohm effect, Bell inequalities, Berry's phase). PACS 42.50.Dv ­ Nonclassical field states; squeezed- ments. PACS 42.50 ­ Quantum optics. 1. ­ Introduction The problem of achieving a sequence

D'Ariano, Giacomo Mauro

267

Mapping of the Marangoni effect in soap films us-ing Young's double slit experiment.  

E-print Network

in Aharonov-Bohm type experiments [26]. R. Feynman himself said from this experiment: "It is a phenomenon films via the change of the phase due to the modification of the effective optical length. The aimepl draft Mapping of the Marangoni effect in soap films us- ing Young's double slit experiment

Paris-Sud XI, Université de

268

Electromagnetically-Induced Transparency with Classical and Nonclassical Light  

E-print Network

) to a constant magnetic field and (iii) the Aharonov-Bohm effect [3]. 3. Quantum tomography of slow light EIT with multiple excited levels. © 2007 Optical Society of America OCIS codes: (270.1670) Coherent optical effects of protocols for routing, frequency conversion, and geometric steering of optical modes in atomic systems

Lvovsky, Alexander

269

Remarks on Aharanov-Bohm effect and geometric phase  

Microsoft Academic Search

Recently the physical mechanism for geometric phase in optics has been elucidated in terms of the angular momentum holonomy proposed in 1992. Aharonov and Kaufherr (PRL, 92, 070404, 2004) revisit the Aharonov-Bohm effect, and propose non-local exchange of a conserved, gauge invariant quantity that changes the modular momentum of the particle that is responsible for the AB phase shift. We

S C Tiwari

2004-01-01

270

Nonlinear Fano resonance and bistable wave transmission Andrey E. Miroshnichenko,1  

E-print Network

systems 1 , Aharonov-Bohm interferom- eters 2,3 , and quantum dots 4­6 , resonant light propaga- tion-high bandwidth Devices for Optical Systems (CUDOS), Research School of Physical Sciences and Engineering-dependent bistable resonant transmission or reflection. We identify these effects as the nonlinear Fano resonance

Flach, Sergej

271

Magnonics: Experiment to Prove the Concept V.V. Kruglyak and R.J. Hicken  

E-print Network

within an Aharonov-Bohm geometry14 , and in magnetic logic devices19 . Typically, the spin waves experiment is required to take advantage of effects such as those predicted in Ref. 14. In this paper, we propose an all-optical time domain experiment for investigation of propagating exchange spin waves

Exeter, University of

272

Cross-Polarized Exciton Absorption in Semiconducting Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

The Aharonov-Bohm effect on optical absorption of light polarized perpendicularly to the tube axis in semiconducting carbon nanotubes is studied. The excitation energy quadratically decreases with the flux around zero in contrast to the linear splitting for light polarized parallel to the axis.

Uryu, Seiji; Ando, Tsuneya

273

V O L U M E 60, N U M B E R 1 3 PHYSICAL REVIEW LETTERS 28 M ARCH 1988 Study of the Aharonov-Anandan Quantum Phase by NMR Interferometry  

E-print Network

a simple connection of the geometrical phase to the Aharonov-Bohm effect 4 which does not invoke adiabati the subject of NMR experiments in this Letter and optical experiments in the accompanying Letters by Chiao with state 2 is detected by means of its effect on transi- tion 1-2. Suppose the system begins in thermal

Suter, Dieter

274

PHYSICAL REVIEW B 89, 205112 (2014) Toroidal dipolar excitation and macroscopic electromagnetic properties of metamaterials  

E-print Network

observation of the time-dependent Aharonov-Bohm effect [9,12]. Due to complexity of the current distribution metamaterials, and then at optical frequencies, where they could be important in spectroscopy analysis of a wide for nonlinear optics [17­22]. Despite its intriguing properties, the toroidal dipole is usu- ally omitted

Zheludev, Nikolay

275

Sagnac Interference in Carbon Nanotube Loops Gil Refael,1  

E-print Network

-Zehnder interferometers reveal Aharonov-Bohm oscillations and magentic-field edge channels, [7­11], and can probe exotic electronic interference mode in nanotubes--the Sagnac interference [23]. The optical Sagnac effect measures for the effect to appear, are shown to be much larger than those of the related Fabry-Perot interference. We

Bockrath, Marc

276

PHYSICAL REVIEW B 83, 195411 (2011) Polarization dependence of coherent phonon generation and detection in highly-aligned  

E-print Network

magnetic field, and with the added properties of the Aharonov-Bohm effect, the electronic band structure theory with experiment in detail for RBM CPs created by pumping at the E44 optical transition for Type II CP spectroscopy experiments and, after including misalignment effects to our fitting, we

Kono, Junichiro

277

d'Ordre: D.U. 2069 UNIVERSITE BLAISE PASCAL  

E-print Network

of exciton-polaritons 83 4.1 Aharonov-Bohm phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 semiconductor structures: excitons . . . . . . . . . . . . 12 1.2 Optical mode confinement,version1-13Oct2011 #12;4 CONTENTS 3 Josephson effect of excitons and exciton-polaritons 65 3

Boyer, Edmond

278

"The Picture is My Life" Shuji Hasegawa  

E-print Network

at the final stage of verification experiments of the Aharonov-Bohm effect using a ring magnet covered with a toroidal superconductor. I participated in the sample preparation and optical reconstruction processes. In addition, I engaged in the development of a new computer-controlled optical reconstruction interferometer

Hasegawa, Shuji

279

Localized polarons and doorway vibrons in finite quantum structures H. Fehske,1 G. Wellein,2 J. Loos,3 and A. R. Bishop4  

E-print Network

.g., for magnetic molecular transistors,3,5,6 quantum dots,7 tunneling diodes and Aharonov-Bohm rings,8 metal, and optical response calculated by exact numerical techniques. DOI: 10.1103/PhysRevB.77.085117 PACS number importance.4 Pho- non and polaron effects in nanoscale devices have been ex- tensively discussed, e

Fehske, Holger

280

Quantum mechanical effects of topological origin  

NASA Technical Reports Server (NTRS)

Following a brief review of the original Casimir and Aharonov-Bohm effects, some other effects of similar natures are mentioned. A Casimir interaction between AB fluxes is presented. Possible realizations of the Casimir effects for massive charged fields in solid state structures and a new AB effect for photons are suggested.

Duru, I. H.

1993-01-01

281

An Introduction to the Basics of Dephasing  

NSDL National Science Digital Library

This is a simplified introduction to the physics of dephasing of quantum systems. It covers the basics of interacting quantum systems, entanglement, dephasing, dissipation, and quantum measurements. Examples used include ensembles of spins, quantum Brownian motion, and the Aharonov-Bohm effect.

Marquardt, Florian

2004-03-29

282

caba de ser publicado em Portugal, pela mo da editora universitria IST Press,  

E-print Network

livro de divulgação cien- tífica: Fluidos fora da lei ­ a história dos cristais líquidos: de curiosidade gran- des investigadores mundiais na área dos cris- tais líquidos. O seu livro é notável a vários

Sluckin, Tim

283

Electron Matter Optics  

NASA Astrophysics Data System (ADS)

Our group has realized a Mach-Zehnder interferometer for electron matter waves and a source of femtosecond electron pulses. In the first experiment a highly collimated electron beam passes through three gold coated nano-fabricated gratings and reveals interference fringes. Measured dephasing processes poses limitations on the low energy use of this device. In the second experiment a femtosecond laser pump-probe experiment on a field emission tip was performed. Control of the electron emission mechanisms, which are multi-photon absorption and optical field tunneling, may be useful for the production of attosecond electron pulses. We will discuss the use of the first device to test the dispersionless nature of the Aharonov-Bohm effect and the use of the second device to test the macroscopic limit of the Aharonov-Bohm effect.

Batelaan, Herman

2007-06-01

284

Effects of lateral asymmetry on electronic structure of strained semiconductor nanorings in a magnetic field  

NASA Astrophysics Data System (ADS)

The influence of lateral asymmetry on the electronic structure and optical transitions in elliptical strained InAs nanorings is analyzed in the presence of a perpendicular magnetic field. Two-dimensional rings are assumed to have elliptical inner and outer boundaries oriented in mutually orthogonal directions. The influence of the eccentricity of the ring on the energy levels is analyzed. For large eccentricity of the ring, we do not find any Aharonov-Bohm effect, in contrast to circular rings. Rather, the single-particle states of the electrons and the holes are localized as in two laterally coupled quantum dots formed in the lobes of the nanoring. Our work indicates that the control of shape is important for the existence of the Aharonov-Bohm effect in semiconductor nanorings.

Miloševi?, M. M.; Tadi?, M.; Peeters, F. M.

2008-11-01

285

Effects of lateral asymmetry on electronic structure of strained semiconductor nanorings in a magnetic field.  

PubMed

The influence of lateral asymmetry on the electronic structure and optical transitions in elliptical strained InAs nanorings is analyzed in the presence of a perpendicular magnetic field. Two-dimensional rings are assumed to have elliptical inner and outer boundaries oriented in mutually orthogonal directions. The influence of the eccentricity of the ring on the energy levels is analyzed. For large eccentricity of the ring, we do not find any Aharonov-Bohm effect, in contrast to circular rings. Rather, the single-particle states of the electrons and the holes are localized as in two laterally coupled quantum dots formed in the lobes of the nanoring. Our work indicates that the control of shape is important for the existence of the Aharonov-Bohm effect in semiconductor nanorings. PMID:21832775

Miloševi?, M M; Tadi?, M; Peeters, F M

2008-11-12

286

Persistent charge and spin currents in a quantum ring using Green's function technique: Interplay between magnetic flux and spin-orbit interactions  

NASA Astrophysics Data System (ADS)

We put forward a new approach based on Green's function formalism to evaluate precisely persistent charge and spin currents in an Aharonov-Bohm ring subjected to Rashba and Dresselhaus spin-orbit interactions. Unlike conventional methods our present scheme circumvents direct evaluation of eigenvalues and eigenstates of the system Hamiltonian to determine persistent currents which essentially reduces possible numerical errors, especially for larger rings. The interplay of Aharonov-Bohm flux and spin-orbit interactions in persistent charge and spin currents of quantum rings is analyzed in detail and our results lead to a possibility of estimating the strength of any one of the spin-orbit fields provided the other one is known. All these features are exactly invariant even in the presence of impurities, and therefore, can be substantiated experimentally.

Maiti, Santanu K.; Dey, Moumita; Karmakar, S. N.

2014-11-01

287

More than one mystery: Quantum interference with correlated charged particles and magnetic fields  

NASA Astrophysics Data System (ADS)

Examples of charged-particle interferometry are descibed whereby isolated magnetic fields—i.e., fields through which the particles do not pass—influence the clustering, as well as spatial distribution, of the particles. The configurations, which combine features characteristic of (i) Aharonov-Bohm and Hanbury Brown-Twiss experiments, and (ii) Aharonov-Bohm and Einstein-Podolsky-Rosen experiments, manifest simultaneously the effects of three distinct kinds of interference: (i) interference, dependent upon optical path length difference, resulting from wavelike propagation of particles; (ii) interference, dependent upon confined magnetic flux, resulting from particle charge and spatial topology; and (iii) interference, dependent upon quantum statistics, resulting from particle indistinguishability under exchange.

Silverman, M. P.

1993-06-01

288

Magneto-photoluminescence studies of CdTe\\/CdSe\\/ZnS nanoparticles  

Microsoft Academic Search

Recently, the effect of the magnetic flux on the excitonic energy has received much attention. Optical Aharonov-Bohm was observed on negatively charged exciton in InGaAs\\/GaAs quantum ring as well as neutral exciton in type-II InP-GaAs heterostrcture. In this talk we'll present our magneto-photoluminescence studies on the optical properties of CdTe\\/CdSe\\/ZnS system. The nanoparticles that were grown by chemical method have

Y. H. Chang; C. C. Huang; L. W. Chang; C. H. Hsu; Chih-Wei Lai; Chien-Liang Liu; Pi-Tai Chou; Y. W. Suen

2008-01-01

289

Atomic Stern-Gerlach interferences with time-dependent magnetic fields  

SciTech Connect

In atomic Stern-Gerlach (polarization) interferometry with time-dependent magnetic fields both the spatial and temporal parts of the atomic phase are generally affected. This leads to a total energy shift and to an inelastic momentum transfer. Some of the related effects are studied using a beam of metastable hydrogen atoms. In particular the scalar Aharonov-Bohm effect and its nondispersivity are considered, in addition to other phase shift effects occurring where the field gradient differs from zero.

Nic Chormaic, S.; Miniatura, C.; Gorceix, O.; Viaris de Lesegno, B.; Robert, J.; Feron, S.; Lorent, V.; Reinhardt, J.; Baudon, J.; Rubin, K. (Laboratoire de Physique des Lasers, Universite Paris-Nord, av. J.B. Clement, 93430-Villetaneuse (France))

1994-01-03

290

General relativity in electrical engineering  

NASA Astrophysics Data System (ADS)

In electrical engineering metamaterials have been developed that offer unprecedented control over electromagnetic fields. Here we show that general relativity lends the theoretical tools for designing devices made of such versatile materials. We consider media that facilitate space-time transformations and include negative refraction. Our theory unifies the concepts operating behind the scenes of perfect invisibility devices, perfect lenses, the optical Aharonov-Bohm effect and electromagnetic analogs of the event horizon, and may lead to further applications.

Leonhardt, U.; Philbin, T. G.

2007-05-01

291

Interband Recombination Dynamics in Resonantly Excited Single-Walled Carbon Nanotubes G. N. Ostojic, S. Zaric, and J. Kono*  

E-print Network

of the Burstein-Moss effect. DOI: 10.1103/PhysRevLett.92.117402 PACS numbers: 78.47.+p, 73.22.­f, 78.67.Ch Optical properties via the Aharonov-Bohm phase [3]. Furthermore, high-order harmonic generation is ex- pected of optical phenomena that arise from their unique tubular structure. Linear and nonlinear optical

Kono, Junichiro

292

Matter-wave interferometry for back-action-evading measurement of optical energy density  

Microsoft Academic Search

The minimal-coupling Hamiltonian that describes the quantum-mechanical interaction of charged matter and electromagnetic fields, implies the existence of an optical analog of the Aharonov-Bohm effect that may be observable as a resistivity change in mesoscopic conductor loops. In superconducting quantum interference devices (SQUID's) the ponderomotive potential adds to the chemical potential, altering the Josephson oscillation frequency. These interactions do not

M. D. Levenson

1990-01-01

293

Interband Magneto-Optics in Carbon Nanotubes in Pulsed High Magnetic Fields  

Microsoft Academic Search

To extend our earlier work ootnotetextS. Zaric et al., Science 304, 1129 (2004). on the Aharonov-Bohm effect in carbon nanotubes to higher fields, we have performed interband magneto-absorption and magneto-photoluminescence experiments in micelle-suspended single-walled carbon nanotubes in pulsed high magnetic fields up to 71 T. Because of their anisotropic magnetic susceptibilities, the nanotubes dynamically align in response to the pulsed

S. Zaric; O. Portugall; S. A. Crooker; X. Wei; H. U. Mueller; V. C. Moore

2005-01-01

294

Remarks on Aharanov-Bohm effect and geometric phase  

Microsoft Academic Search

Recently the physical mechanism for geometric phase in optics has been\\u000aelucidated in terms of the angular momentum holonomy proposed in 1992. Aharonov\\u000aand Kaufherr (PRL, 92, 070404, 2004) revisit the Aharonov-Bohm effect, and\\u000apropose non-local exchange of a conserved, gauge invariant quantity that\\u000achanges the modular momentum of the particle that is responsible for the AB\\u000aphase shift. We

S. C. Tiwari

2004-01-01

295

Optical vortex solitons and nonlinear Aharanov-Bohm effect  

Microsoft Academic Search

We study the scattering properties of optical vortex solitons generated in a self-defocusing nonlinear Kerr medium, analyzing both linear and nonlinear wave scattering. In the linear case, we find a splitting of a plane-wave front at the optical vortex proportional to the vortex circulation, similar to what occurs in the scattered wave of electrons for the Aharonov-Bohm effect. For larger

Dragomir Neshev; Alexander A. Nepomnyashchy; Yuri S. Kivshar

2001-01-01

296

Topological Raman band in the carbon nanohorn.  

PubMed

Raman spectroscopy has been used in chemistry and physics to investigate the fundamental process involving light and phonons. The carbon nanohorn introduces a new subject to Raman spectroscopy, namely topology. We show theoretically that a photoexcited carrier with a nonzero winding number activates a topological D Raman band through the Aharonov-Bohm effect. The topology-induced D Raman band can be distinguished from the ordinary D Raman band for a graphene edge by its peak position. PMID:24074113

Sasaki, Ken-ichi; Sekine, Yoshiaki; Tateno, Kouta; Gotoh, Hideki

2013-09-13

297

Solution of the Dirac equation with magnetic monopole and pseudoscalar potentials  

NASA Astrophysics Data System (ADS)

The Dirac equation in the presence of the Dirac magnetic monopole potential, the Aharonov-Bohm potential, a Coulomb potential and a pseudo-scalar potential, is solved by separation of variables using the spinweighted spherical harmonics. The energy spectrum and the form of the spinor functions are obtained. It is shown that the number j in spin-weighted spherical harmonics must be greater than.

Aghaei, Sohrab; Chenaghlou, Alireza

2014-04-01

298

Dirac bound states of anharmonic oscillator in external fields  

E-print Network

We explore the effect of the external magnetic and Aharonov-Bohm (AB) flux fields on the energy levels of Dirac particle subjects to mixed scalar and vector anharmonic oscillator field in the two-dimensional (2D) space. We calculate the exact energy eigenvalues and the corresponding un-normalized two-spinor-components wave functions in terms of the chemical potential parameter, magnetic field strength, AB flux field and magnetic quantum number by using the Nikiforov-Uvarov (NU) method.

Majid Hamzavia; Sameer M. Ikhdair; Babatunde J. Falaye

2014-01-28

299

Modeling of the Magnetization Behavior of Realistic Self-Organized InAs/GaAs Quantum Craters as Observed with Cross-Sectional STM  

NASA Astrophysics Data System (ADS)

Recently, using cross-sectional scanning-tunneling microscopy (X-STM), it was shown that self-organized ring-like InAs quantum dots are much smaller in diameter than it is expected from atomic force microscopy measurements and, moreover, that they possess a depression rather than an opening in the central region. For those quantum craters, we analyze the possibility to reveal the electronic properties (like the Aharonov-Bohm oscillations) peculiar to doubly connected geometry of quantum rings.

Fomin, V. M.; Gladilin, V. N.; Devreese, J. T.; Offermans, P.; Koenraad, P. M.; Wolter, J. H.; García, J. M.; Granados, D.

2005-06-01

300

EM International. Volume 1  

SciTech Connect

It is the intent of EM International to describe the Office of Environmental Restoration and Waste Management`s (EM`s) various roles and responsibilities within the international community. Cooperative agreements and programs, descriptions of projects and technologies, and synopses of visits to international sites are all highlighted in this semiannual journal. Focus on EM programs in this issue is on international collaboration in vitrification projects. Technology highlights covers: in situ sealing for contaminated sites; and remote sensors for toxic pollutants. Section on profiles of countries includes: Arctic contamination by the former Soviet Union, and EM activities with Germany--cooperative arrangements.

Not Available

1993-07-01

301

EMS in the pueblos.  

PubMed

Imagine creating a movie by excerpting scenes from "Dances With Wolves," splicing it with footage from "Code 3" or "Emergency Response" and then flavoring the script with the mystery of a Tony Hillerman novel. A film producer would probably find it quite difficult to choreograph a finished product from such a compilation of material. To hundreds of Native American EMS providers, however, such a movie is played out every day in Indian country. And with this movie come some real-life problems, including trauma, which is the number-one cause of premature death among Native Americans. But a high trauma rate is just one of the challenges facing tribal EMS responders. There's also prolonged response and transport, the problems involved in maintaining the unique culture and standard of care, the challenges of tribal EMS administration and EMS education of Native American students, and the unsure future of Native American EMS. Beyond that, there's the fact that EMS is a s unique to each Indian reservation as are the cultures of the native peoples who reside on these lands. Yet while no two systems are alike, most tribal EMS providers face similar challenges. PMID:10131740

Vigil, M A

1994-02-01

302

Environmental Media Services (EMS)  

NSDL National Science Digital Library

Environmental Media Services (EMS) is a nonprofit communications clearinghouse committed to the expansion of media coverage on critical environmental and public health issues. True to their mission, EMS staff "build relationships with top scientists, physicians, and other experts to bring journalists the latest and most credible information." EMS's modest homepage is free of clutter but full of content. While several sections are under construction and updates (currently) appear irregular, a series of available articles provides useful summaries of important environmental news issues over the past six months. Current articles include "The impacts of global warming on the oceans" and "Cool companies," among others.

303

EM Radiation Program  

NSDL National Science Digital Library

The EM Radiation program displays the electric field vectors (in the x-y plane) and magnetic field contours (for the field in the z direction) calculated from the Lienard-Wiechert potentials for a charged particle. The default scenario shows the resulting radiation from a charged particle in simple harmonic motion. Additional particle trajectories can be specified using the Display | Switch GUI menu item. EM Radiation is an Open Source Physics program written for the teaching of electromagnetism. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the em_radiation.jar file will run the program if Java is installed. Other electromagnetism programs are also available. They can be found by searching ComPADRE for Open Source Physics, OSP, or electromagnetism.

Christian, Wolfgang

2008-05-20

304

Interference between two indistinguishable electrons from independent sources  

NASA Astrophysics Data System (ADS)

Very much like the ubiquitous quantum interference of a single particle with itself, quantum interference of two independent, but indistinguishable, particles is also possible. For a single particle, the interference is between the amplitudes of the particle's wavefunctions, whereas the interference between two particles is a direct result of quantum exchange statistics. Such interference is observed only in the joint probability of finding the particles in two separated detectors, after they were injected from two spatially separated and independent sources. Experimental realizations of two-particle interferometers have been proposed; in these proposals it was shown that such correlations are a direct signature of quantum entanglement between the spatial degrees of freedom of the two particles (`orbital entanglement'), even though they do not interact with each other. In optics, experiments using indistinguishable pairs of photons encountered difficulties in generating pairs of independent photons and synchronizing their arrival times; thus they have concentrated on detecting bunching of photons (bosons) by coincidence measurements. Similar experiments with electrons are rather scarce. Cross-correlation measurements between partitioned currents, emanating from one source, yielded similar information to that obtained from auto-correlation (shot noise) measurements. The proposal of ref. 3 is an electronic analogue to the historical Hanbury Brown and Twiss experiment with classical light. It is based on the electronic Mach-Zehnder interferometer that uses edge channels in the quantum Hall effect regime. Here we implement such an interferometer. We partitioned two independent and mutually incoherent electron beams into two trajectories, so that the combined four trajectories enclosed an Aharonov-Bohm flux. Although individual currents and their fluctuations (shot noise measured by auto-correlation) were found to be independent of the Aharonov-Bohm flux, the cross-correlation between current fluctuations at two opposite points across the device exhibited strong Aharonov-Bohm oscillations, suggesting orbital entanglement between the two electron beams.

Neder, I.; Ofek, N.; Chung, Y.; Heiblum, M.; Mahalu, D.; Umansky, V.

2007-07-01

305

Generation of uniform synthetic magnetic fields by split driving of an optical lattice  

NASA Astrophysics Data System (ADS)

We describe a method to generate a synthetic gauge potential for ultracold atoms held in an optical lattice. Our approach uses a time-periodic driving potential based on quickly alternating two Hamiltonians to engineer the appropriate Aharonov-Bohm phases, and permits the simulation of a uniform tunable magnetic field. We explicitly demonstrate that our split-driving scheme reproduces the behavior of a charged quantum particle in a magnetic field over the complete range of field strengths, and obtain the Hofstadter butterfly band structure for the Floquet quasienergies.

Creffield, C. E.; Sols, F.

2014-08-01

306

Bose-Einstein condensates in strong electric fields: Effective gauge potentials and rotating states  

SciTech Connect

Magnetically trapped atoms in Bose-Einstein condensates are spin polarized. Since the magnetic field is inhomogeneous, the atoms acquire Berry phases of the Aharonov-Bohm type during adiabatic motion. In the presence of an electric field, there is an additional Aharonov-Casher effect. Taking into account the limitations on the strength of the electric fields due to the polarizability of the atoms, we investigate the extent to which these effects can be used to induce rotation in a Bose-Einstein condensate.

Kailasvuori, J.M.; Hansson, T.H.; Kavoulakis, G.M. [Department of Physics, University of Stockholm, Stockholm Center for Physics, Astronomy and Biotechnology, S-11385 Stockholm (Sweden); Mathematical Physics, Lund Institute of Technology, P.O. Box 118, S-22100 Lund (Sweden)

2002-11-01

307

Detection of Weak Gravitational Waves by Interferometric Methods and Problem of Invertible Calculations  

E-print Network

The fundamental features of the detection of non-stationary undulatory perturbations of metrics based on the interference effects are considered. The advantage of the Aharonov-Bohm effect in superconductors for these purposes in comparison with the ordinary optical interference is demonstrated. Some circuitries of the interferometric detectors in order to be used with SQUID are suggested. The possibilities of lowering the noise temperature of the ultraweak signals detectors based on the analogy between the processes of high-sensitive measurements and the reversible calculations are discussed.

Golovashkin, A I; Kuleshova, G V; Tzhovrebov, A M; Khanh, T Q; Khanh, Tran Quoc

2003-01-01

308

Cold Atoms in Non-Abelian Gauge Potentials: From the Hofstadter Moth to Lattice Gauge Theory  

SciTech Connect

We demonstrate how to create artificial external non-Abelian gauge potentials acting on cold atoms in optical lattices. The method employs atoms with k internal states, and laser assisted state sensitive tunneling, described by unitary kxk matrices. The single-particle dynamics in the case of intense U(2) vector potentials lead to a generalized Hofstadter butterfly spectrum which shows a complex mothlike structure. We discuss the possibility to realize non-Abelian interferometry (Aharonov-Bohm effect) and to study many-body dynamics of ultracold matter in external lattice gauge fields.

Osterloh, K. [Institut fuer Theoretische Physik, Universitaet Hannover, D-30167 Hannover (Germany); Baig, M. [IFAE, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Santos, L. [Institut fuer Theoretische Physik III, Universitaet Stuttgart, D-70550 Stuttgart (Germany); Zoller, P. [Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Lewenstein, M. [Institut fuer Theoretische Physik, Universitaet Hannover, D-30167 Hannover (Germany); ICFO-Institut de Ciencies Fotoniques, 08034 Barcelona (Spain)

2005-07-01

309

Interference due to Coherence Swapping  

E-print Network

We propose a method called `coherence swapping' which enables us to create superposition of a particle in two distinct paths, which is fed with initially incoherent, independent radiations. This phenomenon is also present for the charged particles, and can be used to swap the effect of flux line due to Aharonov-Bohm effect. We propose an optical version of the experimental set-up to test the coherence swapping. The phenomenon, which is simpler than entanglement swapping or teleportation, raises some fundamental questions about true nature of wave-particle duality, and also opens up the possibility of studying the quantum erasure from a new angle.

Pati, A K; Pati, Arun K.; Zukowski, Marek

2001-01-01

310

Cold atoms in non-Abelian gauge potentials: from the Hofstadter "moth" to lattice gauge theory.  

PubMed

We demonstrate how to create artificial external non-Abelian gauge potentials acting on cold atoms in optical lattices. The method employs atoms with k internal states, and laser assisted state sensitive tunneling, described by unitary k x k matrices. The single-particle dynamics in the case of intense U2 vector potentials lead to a generalized Hofstadter butterfly spectrum which shows a complex mothlike structure. We discuss the possibility to realize non-Abelian interferometry (Aharonov-Bohm effect) and to study many-body dynamics of ultracold matter in external lattice gauge fields. PMID:16090589

Osterloh, K; Baig, M; Santos, L; Zoller, P; Lewenstein, M

2005-07-01

311

General Relativity in Electrical Engineering  

E-print Network

In electrical engineering metamaterials have been developed that offer unprecedented control over electromagnetic fields. Here we show that general relativity lends the theoretical tools for designing devices made of such versatile materials. Given a desired device function, the theory describes the electromagnetic properties that turn this function into fact. We consider media that facilitate space-time transformations and include negative refraction. Our theory unifies the concepts operating behind the scenes of perfect invisibility devices, perfect lenses, the optical Aharonov-Bohm effect and electromagnetic analogs of the event horizon, and may lead to further applications.

Leonhardt, Ulf; 10.1088/1367-2630/8/10/247

2009-01-01

312

Band-edge exciton states in a single-walled carbon nanotube revealed by magneto-optical spectroscopy in ultrahigh magnetic fields  

NASA Astrophysics Data System (ADS)

We report a high-field magneto-optical study on first and second subband transitions of single-chirality single-walled carbon nanotubes. The ordering and relative energy splitting between bright and dark excitonic states were found to be inverse between the first and second subbands. We verified that the zero-momentum dark singlet exciton lies below the bright exciton for the first subband transitions, while for the second subband transitions, it was found to have higher energy than the bright excitonic state. The effect of this peculiar excitonic structure was found to manifest itself in distinctive Aharonov-Bohm splitting in ultrahigh magnetic fields up to 190 T.

Zhou, Weihang; Sasaki, Tatsuya; Nakamura, Daisuke; Liu, Huaping; Kataura, Hiromichi; Takeyama, Shojiro

2013-06-01

313

Remarks on Aharanov-Bohm effect and geometric phase  

E-print Network

Recently the physical mechanism for geometric phase in optics has been elucidated in terms of the angular momentum holonomy proposed in 1992. Aharonov and Kaufherr (PRL, 92, 070404, 2004) revisit the Aharonov-Bohm effect, and propose non-local exchange of a conserved, gauge invariant quantity that changes the modular momentum of the particle that is responsible for the AB phase shift. We suggest that the net angular momentum shifts proposed for GP may be analogous to the shift in the modulus momentum for the AB effect. At a single photon or electron level such non-trivial, geometric effects seem to hint at a new physics.

Tiwari, S C

2004-01-01

314

Nonlocal Pancharatnam phase in two-photon interferometry  

NASA Astrophysics Data System (ADS)

We propose a polarized intensity interferometry experiment, which measures the nonlocal Pancharatnam phase acquired by a pair of Hanbury-Brown-Twiss photons. The setup involves two polarized thermal sources illuminating two polarized detectors. Varying the relative polarization angle of the detectors introduces a two-photon geometric phase. Local measurements at either detector do not reveal the effects of the phase, which is an optical analog of the multiparticle Aharonov-Bohm effect. The geometric phase sheds light on the three-slit experiment and suggests ways of tuning entanglement.

Mehta, Poonam; Samuel, Joseph; Sinha, Supurna

2010-09-01

315

Flux sensitivity of a piecewise normal and superconducting metal loop  

SciTech Connect

We consider a loop composed of a superconducting segment and a normal segment with an Aharonov-Bohm flux through the hole of the loop. The normal segment is assumed to be long compared to the superconducting coherence length xi but short compared to a mean inelastic diffusion length. The elementary excitation spectrum of the ground state of this loop is periodic with period hc/2e as long as the superconducting segment is larger than xi. If the superconducting segment length becomes of the order of xi, quasiparticles can tunnel through the superconducting gap and give rise to an excitation spectrum which is periodic with period hc/e. .AE

Buettiker, M.; Klapwijk, T.M.

1986-04-01

316

The atomic quantum ring  

NASA Astrophysics Data System (ADS)

We investigate the dynamics of neutral fermions trapped in a one-dimensional ring. We construct an effective magnetic field in the ring using the adiabatic motion of dark states created by light beams carrying an orbital angular momentum. We illustrate the effect of the orbital angular momentum by looking at the induced mass current and show how the Aharonov-Bohm effect manifests itself in an atomic Fermi gas as a periodic mass current as a function of the optically induced artificial magnetic flux.

Öhberg, P.

2011-06-01

317

Nonlocal Pancharatnam phase in two-photon interferometry  

SciTech Connect

We propose a polarized intensity interferometry experiment, which measures the nonlocal Pancharatnam phase acquired by a pair of Hanbury-Brown-Twiss photons. The setup involves two polarized thermal sources illuminating two polarized detectors. Varying the relative polarization angle of the detectors introduces a two-photon geometric phase. Local measurements at either detector do not reveal the effects of the phase, which is an optical analog of the multiparticle Aharonov-Bohm effect. The geometric phase sheds light on the three-slit experiment and suggests ways of tuning entanglement.

Mehta, Poonam; Samuel, Joseph; Sinha, Supurna [Raman Research Institute, Bangalore 560 080 (India)

2010-09-15

318

Single molecular shuttle-junction: Shot noise and decoherence  

NASA Astrophysics Data System (ADS)

Single molecular shuttle-junction is one kind of nanoscale electromechanical tunneling system. In this junction, a molecular island oscillates depending on its charge occupation, and this charge dependent oscillation leads to modulation of electron tunneling through the molecular island. This paper reviews recent development on the study of current, shot noise and decoherence of electrons in the single molecular shuttle-junction. We will give detail discussions on this topic using the typical system model, the theory of fully quantum master equation and the Aharonov-Bohm interferometer.

Lai, Wenxi; Zhang, Chao; Ma, Zhongshui

2014-09-01

319

Gauge Field Optics with Anisotropic Media  

E-print Network

By considering gauge transformations on the macroscopic Maxwell's equations, a two dimensional gauge field, with its pseudo magnetic field in the real space, is identified as tilted anisotropy in the constitutive parameters. We show that optical spin Hall effect and one-way edge states become possible simply by using anisotropic media with broadband response. The proposed gauge field also allows us to design an optical isolator based on the Aharonov-Bohm effect. Our approach will be useful in spoof magneto-optics with arbitrary magnetic fields mimicked by metamaterials with subwavelength unit cells. It also serves as a generic way to design polarization-dependent devices.

Liu, Fu

2014-01-01

320

Noise-induced phase transition in the electronic Mach-Zehnder interferometer.  

PubMed

We consider dephasing in the electronic Mach-Zehnder interferometer strongly coupled to current noise created by a voltage biased quantum point contact (QPC). We find the visibility of Aharonov-Bohm oscillations as a function of voltage bias and express it via the cumulant generating function of noise. In the large-bias regime, high-order cumulants of current add up to cancel the dilution effect of a QPC. This leads to an abrupt change in the dependence of the visibility on voltage bias which occurs at the QPC's transparency T=1/2. Quantum fluctuations in the vicinity of this point smear out the sharp transition. PMID:19659304

Levkivskyi, Ivan P; Sukhorukov, Eugene V

2009-07-17

321

Semiclassical Ballistic Transport through a Circular Microstructure in Weak Magnetic Fields  

NASA Astrophysics Data System (ADS)

We study magneto-transport through a weakly open circular microstructure in the perpendicular weak magnetic fields by a semiclassical approximation within the framework of the Fraunhofer diffraction effect at the lead openings. It is found that the peak positions of the transmission power spectrum can be related to simple trajectories according to classical dynamics. Moreover, we formulate the fluctuations in the transmission amplitude as functions of both the wave number k and the magnetic field B in terms of different classical trajectories, and the Aharonov—Bohm phase of the directed areas enclosed by these trajectories that reflect the quantum interference effect.

Zhang, Yan-Hui; Cai, Xiang-Ji; Li, Zong-Liang; Jiang, Guo-Hui; Yang, Qin-Nan; Xu, Xue-You

2013-04-01

322

Quasiballistic Transport of Dirac Fermions in a Bi2Se3 Nanowire  

NASA Astrophysics Data System (ADS)

Quantum coherent transport of surface states in a mesoscopic nanowire of the three-dimensional topological insulator Bi2Se3 is studied in the weak-disorder limit. At very low temperatures, many harmonics are evidenced in the Fourier transform of Aharonov-Bohm oscillations, revealing the long phase coherence length of spin-chiral Dirac fermions. Remarkably, from their exponential temperature dependence, we infer an unusual 1/T power law for the phase coherence length L?(T). This decoherence is typical for quasiballistic fermions weakly coupled to their environment.

Dufouleur, J.; Veyrat, L.; Teichgräber, A.; Neuhaus, S.; Nowka, C.; Hampel, S.; Cayssol, J.; Schumann, J.; Eichler, B.; Schmidt, O. G.; Büchner, B.; Giraud, R.

2013-05-01

323

Effect of morphology on spectral properties of magneto-trion X+ in vertically coupled type II quantum dots  

NASA Astrophysics Data System (ADS)

The energy spectrum of a positively charged exciton confined in vertically coupled type II quantum dots with different morphologies in the presence of the external magnetic field is studied. The effect of the quantum dot morphology on the curves of the lowest energy levels as functions of the magnetic field is analyzed. It is shown that a strong correlation presented in this system generates the Aharonov-Bohm oscillations of the lower energy levels similar to those in wide quantum ring. The novel curves of the trion energies dependences on the external magnetic field for the disk-like, lens-like, and cone-like structures are presented.

Horta-Piñeres, Sindi; Elizabeth Escorcia-Salas, G.; Mikhailov, I. D.; Sierra-Ortega, J.

2014-11-01

324

Again on coherent states in magnetic-solenoid field  

E-print Network

This article completes our study of coherent states in the so-called magnetic-solenoid field (a colinear combination of a constant uniform magnetic field and Aharonov-Bohm solenoid field) presented in JPA 2010 and 2011. Here we succeeded to prove nontrivial completeness relations for non-relativistic and relativistic coherent states in such a field. In addition, we solve here the relevant Stieltjes moment problem and present a comparative analysis of our coherent states and the well-known in the case of pure uniform magnetic field Malkin-Man'ko coherent states.

Bagrov, V G; Gitman, D M; Gorska, K

2011-01-01

325

Again on coherent states in magnetic-solenoid field  

E-print Network

This article completes our study of coherent states in the so-called magnetic-solenoid field (a colinear combination of a constant uniform magnetic field and Aharonov-Bohm solenoid field) presented in JPA 2010 and 2011. Here we succeeded to prove nontrivial completeness relations for non-relativistic and relativistic coherent states in such a field. In addition, we solve here the relevant Stieltjes moment problem and present a comparative analysis of our coherent states and the well-known in the case of pure uniform magnetic field Malkin-Man'ko coherent states.

V. G. Bagrov; S. P. Gavrilov; D. M. Gitman; K. Gorska

2011-08-25

326

Effective (2+1)-dimensional field theory of fermions: fermion mass generation with Kaluza-Klein fermions and gauge field  

NASA Astrophysics Data System (ADS)

Generation of mass on two-dimensional brane in three-dimensional model with four-fermion interaction including external gauge field A3 is considered. In the framework of this model the generated mass proves to be lighter than Kaluza-Klein modes, thus indicating to a possibility of solving the mass hierarchy problem. Dependence of the effective potential and the coupling constant on characteristics of the model such as compactification radius, gauge field and phase shift parameter was also obtained. It is demonstrated that the generated mass, besides the dynamic part, includes also a kinematic (topological) contribution, i.e. the Aharonov-Bohm phase.

Zhukovsky, V. Ch.; Stepanov, E. A.

2012-12-01

327

Nonlocality as an axiom for quantum theory  

E-print Network

Quantum mechanics and relativistic causality together imply nonlocality: nonlocal correlations (that violate the CHSH inequality) and nonlocal equations of motion (the Aharonov-Bohm effect). Can we invert the logical order? We consider a conjecture that nonlocality and relativistic causality together imply quantum mechanics. We show that correlations preserving relativistic causality can violate the CHSH inequality more strongly than quantum correlations. Also, we describe nonlocal equations of motion, preserving relativistic causality, that do not arise in quantum mechanics. In these nonlocal equations of motion, an experimenter ``jams" nonlocal correlations between quantum systems.

D. Rohrlich; S. Popescu

1995-08-09

328

Surface state dominated transport in topological insulator Bi{sub 2}Te{sub 3} nanowires  

SciTech Connect

We report on low temperature magnetoresistance measurements on single-crystalline Bi{sub 2}Te{sub 3} nanowires synthesized via catalytic growth and post-annealing in a Te-rich atmosphere. The observation of Aharonov-Bohm oscillations indicates the presence of topological surface states. Analyses of Subnikov-de Haas oscillations in perpendicular magnetoresistance yield extremely low two-dimensional carrier concentrations and effective electron masses, and very high carrier mobilities. All our findings are in excellent agreement with theoretical predictions of massless Dirac fermions at the surfaces of topological insulators.

Hamdou, Bacel, E-mail: bhamdou@physnet.uni-hamburg.de; Gooth, Johannes; Dorn, August; Nielsch, Kornelius, E-mail: knielsch@physnet.uni-hamburg.de [Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg (Germany)] [Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg (Germany); Pippel, Eckhard [Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Germany)] [Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Germany)

2013-11-04

329

Double-donor complex in vertically coupled quantum dots in a threading magnetic field  

PubMed Central

We consider a model of hydrogen-like artificial molecule formed by two vertically coupled quantum dots in the shape of axially symmetrical thin layers with on-axis single donor impurity in each of them and with the magnetic field directed along the symmetry axis. We present numerical results for energies of some low-lying levels as functions of the magnetic field applied along the symmetry axis for different quantum dot heights, radii, and separations between them. The evolution of the Aharonov-Bohm oscillations of the energy levels with the increase of the separation between dots is analyzed. PMID:23013550

2012-01-01

330

Photons as quasi-charged particles  

E-print Network

The Schrodinger motion of a charged quantum particle in an electromagnetic potential can be simulated by the paraxial dynamics of photons propagating through a spatially inhomogeneous medium. The inhomogeneity induces geometric effects that generate an artificial vector potential to which signal photons are coupled. This phenomenon can be implemented with slow light propagating through an a gas of double-Lambda atoms in an electromagnetically-induced transparency setting with spatially varied control fields. It can lead to a reduced dispersion of signal photons and a topological phase shift of Aharonov-Bohm type.

K. -P. Marzlin; Juergen Appel; A. I. Lvovsky

2007-04-05

331

General Relativity in Electrical Engineering  

E-print Network

In electrical engineering metamaterials have been developed that offer unprecedented control over electromagnetic fields. Here we show that general relativity lends the theoretical tools for designing devices made of such versatile materials. Given a desired device function, the theory describes the electromagnetic properties that turn this function into fact. We consider media that facilitate space-time transformations and include negative refraction. Our theory unifies the concepts operating behind the scenes of perfect invisibility devices, perfect lenses, the optical Aharonov-Bohm effect and electromagnetic analogs of the event horizon, and may lead to further applications.

Ulf Leonhardt; Thomas G. Philbin

2006-07-17

332

Massive quantum fields in a conical background  

E-print Network

Representations of the Klein-Gordon and Dirac propagators are determined in a $N$ dimensional conical background for massive fields twisted by an arbitrary angle $2\\pi\\sigma$. The Dirac propagator is shown to be obtained from the Klein-Gordon propagator twisted by angles $2\\pi\\sigma\\pm {\\cal D}/2$ where ${\\cal D}$ is the cone deficit angle. Vacuum expectation values are determined by a point-splitting method in the proper time representation of the propagators. Analogies with the Aharonov-Bohm effect are pointed out throughout the paper and a conjecture on an extension to fields of arbitrary spin is given.

E. S. Moreira; Jnr.

1995-02-02

333

Pure phase decoherence in a ring geometry  

SciTech Connect

We study the dynamics of pure phase decoherence for a particle hopping around an N-site ring, coupled both to a spin bath and to an Aharonov-Bohm flux which threads the ring. Analytic results are found for the dynamics of the influence functional and of the reduced density matrix of the particle, both for initial single wave-packet states, and for states split initially into two separate wave packets moving at different velocities. We also give results for the dynamics of the current as a function of time.

Zhu, Z. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Rd., Vancouver, British Columbia, V6T 1Z1 (Canada); Aharony, A.; Entin-Wohlman, O. [Department of Physics and the Ilse Katz Center for Meso- and Nano-Scale Science and Technology, Ben Gurion University, Beer Sheva 84105 (Israel); Pacific Institute of Theoretical Physics, University of British Columbia, 6224 Agricultural Rd., Vancouver, British Columbia, V6T 1Z1 (Canada); Stamp, P. C. E. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Rd., Vancouver, British Columbia, V6T 1Z1 (Canada); Pacific Institute of Theoretical Physics, University of British Columbia, 6224 Agricultural Rd., Vancouver, British Columbia, V6T 1Z1 (Canada)

2010-06-15

334

A Note on the Sagnac Effect for Matter Beams  

E-print Network

We study the Sagnac effect for matter beams, in order to estimate the kinematic corrections to the basic formula, deriving from the position and the extension of the interferometer, and discuss the analogy with the Aharonov-Bohm effect. We show that the formula for the Sagnac time delay is the same for matter and light beams in arbitrary stationary space-times, provided that a suitable condition on the speed of the beams is fulfilled. Hence, the same results obtained for light beams apply to matter beams.

Ruggiero, Matteo Luca

2014-01-01

335

A Note on the Sagnac Effect for Matter Beams  

E-print Network

We study the Sagnac effect for matter beams, in order to estimate the kinematic corrections to the basic formula, deriving from the position and the extension of the interferometer, and discuss the analogy with the Aharonov-Bohm effect. We show that the formula for the Sagnac time delay is the same for matter and light beams in arbitrary stationary space-times, provided that a suitable condition on the speed of the beams is fulfilled. Hence, the same results obtained for light beams apply to matter beams.

Matteo Luca Ruggiero; Angelo Tartaglia

2014-11-01

336

Electron gas high-frequency conductivity on the surface of a nanotube with superlattice in magnetic field  

NASA Astrophysics Data System (ADS)

Kubo formula was obtained for conductivity tensor of electron gas on the surface of nanotube with superlattice in magnetic field. The high-frequency conductivity tensor components were calculated for quantum and quasiclassical cases. Electromagnetic wave Landau damping areas in the tube were determined. The conductivity tensor components show Aharonov-Bohm type oscillations and de Haas-van Alphen ones. When Fermi energy exceeds the miniband width, beatings are observed in the plot of conductivity vs. the tube parameters. Otherwise, the beatings are absent.

Ermolaev, A. M.; Rashba, G. I.

2014-10-01

337

Experimental constraints and a possible quantum Hall state at ? =5 /2  

NASA Astrophysics Data System (ADS)

Several topological orders have been proposed to explain the quantum Hall plateau at ? =5 /2 . The observation of an upstream neutral mode on the sample edge supports the non-Abelian anti-Pfaffian state. On the other hand, tunneling experiments favor the Halperin 331 state which exhibits no upstream modes. No proposed ground states agree with both types of experiments. We find a topological order, compatible with the results of both experiments. That order allows both finite and zero spin polarizations. It is Abelian but its signatures in Aharonov-Bohm interferometry can be similar to those of the Pfaffian and anti-Pfaffian states.

Yang, Guang; Feldman, D. E.

2014-10-01

338

A review of the experimental tests of quantum mechanics  

SciTech Connect

In this paper a review of the experimental tests of quantum mechanics is presented. Tests of the wave-particle duality of matter for atoms, electrons, and neutrons are discussed. Also covered are applications of neutron interferometry to a variety of quantum mechanics tests. Tests of the topological nature of quantum mechanics (Aharonov-Bohm effect, Aharonov-Casher effect, Berry's phase, Aharonov-Anandan phase) are reviewed. Other topics reviewed include the experimental tests of the Bell inequality, nonlinear additions to the Schrodinger equation, the Pauli exclusion principle, the Zeno effect and the uniqueness of [dirac h].

Lamoreaux, S.K. (Washington Univ., Seattle, WA (United States). Dept. of Physics)

1992-10-30

339

Gravitation: global formulation and quantum effects  

NASA Astrophysics Data System (ADS)

A non-integrable phase-factor global approach to gravitation is developed by using the similarity of teleparallel gravity to electromagnetism. The phase shifts of both the COW and the gravitational Aharonov Bohm effects are obtained. It is then shown, by considering a simple slit experiment, that in the classical limit the global approach yields the same result as the gravitational Lorentz force equation of teleparallel gravity. It represents, therefore, the quantum mechanical version of the classical description provided by the gravitational Lorentz force equation. As teleparallel gravity can be formulated independently of the equivalence principle, it will consequently require no generalization of this principle at the quantum level.

Aldrovandi, R.; Pereira, J. G.; Vu, K. H.

2004-01-01

340

Spectra of cylindrical quantum dots: The effect of electrical and magnetic fields together with AB flux field  

NASA Astrophysics Data System (ADS)

We study the spectral properties of electron quantum dots (QDs) confined in 2D parabolic harmonic oscillator influenced by external uniform electrical and magnetic fields together with an Aharonov-Bohm (AB) flux field. We use the Nikiforov-Uvarov method in our calculations. Exact solutions for the energy levels and normalized wave functions are obtained for this exactly soluble quantum system. Based on the computed one-particle energetic spectrum and wave functions, the interband optical absorption GaAs spherical shape parabolic QDs is studied theoretically and the total optical absorption coefficient is calculated.

Ikhdair, Sameer M.; Hamzavi, Majid; Sever, Ramazan

2012-12-01

341

The EM Earthquake Precursor  

NASA Astrophysics Data System (ADS)

Many attempts have been made to determine a sound forecasting method regarding earthquakes and warn the public in turn. Presently, the animal kingdom leads the precursor list alluding to a transmission related source. By applying the animal-based model to an electromagnetic (EM) wave model, various hypotheses were formed, but the most interesting one required the use of a magnetometer with a differing design and geometry. To date, numerous, high-end magnetometers have been in use in close proximity to fault zones for potential earthquake forecasting; however, something is still amiss. The problem still resides with what exactly is forecastable and the investigating direction of EM. After the 1989 Loma Prieta Earthquake, American earthquake investigators predetermined magnetometer use and a minimum earthquake magnitude necessary for EM detection. This action was set in motion, due to the extensive damage incurred and public outrage concerning earthquake forecasting; however, the magnetometers employed, grounded or buried, are completely subject to static and electric fields and have yet to correlate to an identifiable precursor. Secondly, there is neither a networked array for finding any epicentral locations, nor have there been any attempts to find even one. This methodology needs dismissal, because it is overly complicated, subject to continuous change, and provides no response time. As for the minimum magnitude threshold, which was set at M5, this is simply higher than what modern technological advances have gained. Detection can now be achieved at approximately M1, which greatly improves forecasting chances. A propagating precursor has now been detected in both the field and laboratory. Field antenna testing conducted outside the NE Texas town of Timpson in February, 2013, detected three strong EM sources along with numerous weaker signals. The antenna had mobility, and observations were noted for recurrence, duration, and frequency response. Next, two directional techniques were employed, resulting in three mapped, potential epicenters. The remaining, weaker signals presented similar directionality results to more epicentral locations. In addition, the directional results of the Timpson field tests lead to the design and construction of a third prototype antenna. In a laboratory setting, experiments were created to fail igneous rock types within a custom-designed Faraday Cage. An antenna emplaced within the cage detected EM emissions, which were both reproducible and distinct, and the laboratory results paralleled field results. With a viable system and continuous monitoring, a fracture cycle could be established and observed in real-time. Sequentially, field data would be reviewed quickly for assessment; thus, leading to a much improved earthquake forecasting capability. The EM precursor determined by this method may surpass all prior precursor claims, and the general public will finally receive long overdue forecasting.

Jones, K. B., II; Saxton, P. T.

2013-12-01

342

Carcinoma espinocelular cutâneo em cães.  

E-print Network

??Dissertação de Mestrado Integrado em Medicina Veterinária O Carcinoma Espinocelular (CEC) é uma neoplasia com origem nos queratinócitos e representa aproximadamente 5% das neoplasias cutâneas… (more)

Moura, Inês da Costa

2012-01-01

343

Identified EM Earthquake Precursors  

NASA Astrophysics Data System (ADS)

Many attempts have been made to determine a sound forecasting method regarding earthquakes and warn the public in turn. Presently, the animal kingdom leads the precursor list alluding to a transmission related source. By applying the animal-based model to an electromagnetic (EM) wave model, various hypotheses were formed, but the most interesting one required the use of a magnetometer with a differing design and geometry. To date, numerous, high-end magnetometers have been in use in close proximity to fault zones for potential earthquake forecasting; however, something is still amiss. The problem still resides with what exactly is forecastable and the investigating direction of EM. After a number of custom rock experiments, two hypotheses were formed which could answer the EM wave model. The first hypothesis concerned a sufficient and continuous electron movement either by surface or penetrative flow, and the second regarded a novel approach to radio transmission. Electron flow along fracture surfaces was determined to be inadequate in creating strong EM fields, because rock has a very high electrical resistance making it a high quality insulator. Penetrative flow could not be corroborated as well, because it was discovered that rock was absorbing and confining electrons to a very thin skin depth. Radio wave transmission and detection worked with every single test administered. This hypothesis was reviewed for propagating, long-wave generation with sufficient amplitude, and the capability of penetrating solid rock. Additionally, fracture spaces, either air or ion-filled, can facilitate this concept from great depths and allow for surficial detection. A few propagating precursor signals have been detected in the field occurring with associated phases using custom-built loop antennae. Field testing was conducted in Southern California from 2006-2011, and outside the NE Texas town of Timpson in February, 2013. The antennae have mobility and observations were noted for recurrence, duration, and frequency response. At the Southern California field sites, one loop antenna was positioned for omni-directional reception and also detected a strong First Schumann Resonance; however, additional Schumann Resonances were absent. At the Timpson, TX field sites, loop antennae were positioned for directional reception, due to earthquake-induced, hydraulic fracturing activity currently conducted by the oil and gas industry. Two strong signals, one moderately strong signal, and approximately 6-8 weaker signals were detected in the immediate vicinity. The three stronger signals were mapped by a biangulation technique, followed by a triangulation technique for confirmation. This was the first antenna mapping technique ever performed for determining possible earthquake epicenters. Six and a half months later, Timpson experienced two M4 (M4.1 and M4.3) earthquakes on September 2, 2013 followed by a M2.4 earthquake three days later, all occurring at a depth of five kilometers. The Timpson earthquake activity now has a cyclical rate and a forecast was given to the proper authorities. As a result, the Southern California and Timpson, TX field results led to an improved design and construction of a third prototype antenna. With a loop antenna array, a viable communication system, and continuous monitoring, a full fracture cycle can be established and observed in real-time. In addition, field data could be reviewed quickly for assessment and lead to a much more improved earthquake forecasting capability. The EM precursors determined by this method appear to surpass all prior precursor claims, and the general public will finally receive long overdue forecasting.

Jones, Kenneth, II; Saxton, Patrick

2014-05-01

344

Magneto-photoluminescence studies of CdTe/CdSe/ZnS nanoparticles  

NASA Astrophysics Data System (ADS)

Recently, the effect of the magnetic flux on the excitonic energy has received much attention. Optical Aharonov-Bohm was observed on negatively charged exciton in InGaAs/GaAs quantum ring as well as neutral exciton in type-II InP-GaAs heterostrcture. In this talk we'll present our magneto-photoluminescence studies on the optical properties of CdTe/CdSe/ZnS system. The nanoparticles that were grown by chemical method have size of about 6 nm and the band alignment between the core (CdTe) and the shell (CdSe) is a type--II band alignment. The addition of ZnS layer is to passivate the surface of CdSe and to enhance the light emitting efficiency. Magneto-photoluminescence experiment was performed at T=1.4 K with a 14 T superconducting magnet in conjunction with a green diode laser and a monochromator. Oscillation on the peak energy of the photoluminescence spectra as well as oscillation in the integrated intensity as a function of magnetic field were observed and are attributed to the optical Aharonov-Bohm-like effect.

Chang, Y. H.; Huang, C. C.; Chang, L. W.; Hsu, C. H.; Lai, Chih-Wei; Liu, Chien-Liang; Chou, Pi-Tai; Suen, Y. W.

2008-03-01

345

College of Engineering EM Engineering Mechanics  

E-print Network

College of Engineering EM Engineering Mechanics KEY: # = new course * = course changed = course or concur: MA 213. EM 302 MECHANICS OF DEFORMABLE SOLIDS. (3 of Engineering or consent of chairperson, and EM 221; prereq or concur: MA 214. EM 313 DYNAMICS. (3

MacAdam, Keith

346

Investimento ambiental em indústrias sujas e intensivas em recursos naturais e energia  

Microsoft Academic Search

O crescimento industrial brasileiro, a partir do final dos anos setenta, ocorreu com o aumento da participação de indústrias intensivas em recursos naturais, em detrimento da participação de indústrias intensivas em trabalho e dos setores intensivos em atividades tecnológicas mais complexas. Essas transformações, tornando o setor de bens intermediários dominante na estrutura industrial, implicaram em consideráveis mudanças tanto de ordem

Frederico Cavadas Barcellos; Jurandir Carlos de Oliveira; Paulo Gonzaga Mibielli de Carvalho

2009-01-01

347

Turismo Náutico em Angra dos Reis – RJ : a sustentabilidade em questão.  

E-print Network

??Dissertação (mestrado)—Universidade de Brasília, Centro de Desenvolvimento Sustentável, 2011. O turismo está em franca expansão e se desenvolvendo a taxas bastante significativas no Brasil. Em… (more)

Medeiros, Márcio Bastos

2011-01-01

348

Populações estelares em galáxias HII  

NASA Astrophysics Data System (ADS)

Analisamos o conteúdo estelar de 74 galáxias HII a partir do contínuo observado nos espectros ópticos dessas galáxias, utilizando métodos de síntese de população estelar. Descobrimos que todas as galáxias para as quais encontramos soluções contêm uma população estelar velha que domina a massa estelar, e numa maioria dessas também encontramos evidência de uma população de idade intermediaria além da geração jovem que está se formando agora. Concluímos que a formação estelar dessas galáxias se realiza em surtos individuais, Esses surtos são interrompidos por longos períodos de inatividade, com os primeiros consumindo a maior parte do gás. Sugerimos, portanto, que as galáxias HII sejam galáxias anãs normais flagradas em um período de surto.

Westera, P.; Cuisinier, F.; Telles, E.; Kehrig, C.

2003-08-01

349

Burning the EMS candle. EMS shifts and worker fatigue.  

PubMed

Has coffee become your best friend? Do you sleep only in your dreams? Is your bed merely an illusion? If so, you are not alone; sleep deprivation is a fact of life for many EMS personnel. Though widely accepted, isn't it time that we question the effects of those long days and nights? PMID:10116022

McCallion, R; Fazackerley, J

1991-10-01

350

Programa de Ps-Graduao em Economia  

E-print Network

1 Programa de Pós-Graduação em Economia PPG-ECO Universidade de Brasília UnB UNIVERSIDADE DE BRASÍLIA PROGRAMA DE P�S-GRADUA��O EM ECONOMIA EDITAL No. 1/2014 SELE��O DE CANDIDATOS �S VAGAS DO PROGRAMA DE P�S-GRADUA��O EM ECONOMIA PARA O CURSO DE MESTRADO PROFISSIONAL EM ECONOMIA ­ ÁREA DE CONCENTRA��O

Maier, Rudolf Richard

351

WRF-EMS Aviation Products  

NSDL National Science Digital Library

This lesson illustrates how numerical guidance from the Weather Research and Forecasting Model - Environmental Modeling System (WRF-EMS) can be added to surface observations, satellite graphics, and conceptual models of important aviation phenomena, to produce TAFs. Specifically, the lesson describes how visibility, cloud ceilings, and the flight categories variables provide values for aviation forecasts in Africa.

Comet

2013-09-25

352

The European Mobile System (EMS)  

NASA Technical Reports Server (NTRS)

The European Space Agency is presently procuring an L band payload in order to promote a regional European L band system coping with the specific needs of the European market. The payload, and the two communications systems to be supported, are described below. The potential market for EMS in Europe is discussed.

Jongejans, A.; Rogard, R.; Mistretta, I.; Ananasso, F.

1993-01-01

353

Angus Robichaud's Reel G Em D A Bm D7  

E-print Network

Angus Robichaud's Reel 4 4 D G A D D G A D 3 3 G Em D A Bm D7 3 3 G Em D A D Animas Reel Bernie Waugh 4 4 3 3 G D G Bm Em C Am C D G D G Bm Em C Am D G The Arkansas Traveler 4 2 D G A D Em A 3D G A D Em G A D D G D A Bm Em A D G D A Em G A D #12;Asher Rodney Miller 4 4 D Em F#m G A D Em G A D A D1 2

Doyle, Peter

354

Angus Robichaud's Reel G Em D A Bm D7  

E-print Network

Angus Robichaud's Reel 4 4 D G A D D G A D 3 3 G Em D A Bm D7 3 3 G Em D A D Animas Reel Bernie Waugh 4 4 3 3 G D G Bm Em C Am C D G D G Bm Em C Am D G The Arkansas Traveler 4 2 D G A D Em A 3 D G A D Em G A D D G D A Bm Em A D G D A Em G A D #12; Asher Rodney Miller 4 4 D Em F#m G A D Em G A D A D 1

Doyle, Peter

355

DEPARTAMENTO DE ECONOMIA MESTRADO EM ECONOMIA  

E-print Network

DEPARTAMENTO DE ECONOMIA MESTRADO EM ECONOMIA EDITAL DE CONVOCA��O ­ 2014 Estão abertas as inscrições para o Mestrado em Economia da PUC-Rio, a iniciar-se em janeiro de 2014. Para candidatos residentes no Brasil: A admissão é feita através do Exame Nacional de Economia, organizado pela ANPEC

356

DEPARTAMENTO DE ECONOMIA DOUTORADO EM ECONOMIA  

E-print Network

DEPARTAMENTO DE ECONOMIA DOUTORADO EM ECONOMIA EDITAL DE CONVOCA��O ­ 2014 Estão abertas as inscrições para o Doutorado em Economia da PUC-Rio, a iniciar-se em janeiro de 2014. O período de inscrições ]: Departamento de Economia [ref.: Candidatura ao Doutorado] Pontifícia Universidade Católica do Rio de Janeiro

357

Transport and thermodynamic properties of mesoscopic quantum systems  

NASA Astrophysics Data System (ADS)

The transport properties of three-dimensional quantum microconstrictions in field-free conditions and under the influence of magnetic fields of arbitrary strengths and directions are studied via a generalized Buttiker model. It is shown that conductance quantization is influenced by the geometry of the microconstriction (that is, its length and the shape of its transverse cross-section). In a weak longitudinal magnetic field, when rsb{c}? d, where rsb{c} is the cyclotron radius and d the effective transverse size of the narrowing of the microconstriction, the conductance exhibits Aharonov-Bohm type behavior. This behavior transforms in the strong field limit, rsb{c}? d, into Shubnikov-de Haas oscillations with a superimposed Aharonov-Bohm fine-structure. The dependence of the Aharonov-Bohm type features on the length of the microconstriction and on temperature are demonstrated. Effects of the shapes of the cross sections of three-dimensional nanowires on electronic conductance quantization are studied for both hard- and soft-wall potentials. In both models the quantum conductance is determined by both the area and shape of the narrowmost part of the nanowire. For the hard-wall potential the semiclassical (Weyl) correction to the Sharvin formula provides an adequate approximation to the average quantized conductance. For nanowires modeled by soft-wall potentials the average quantum conductance may be well estimated using a classical approximation. Magnetic field switching and blockade of quantum transport through three-dimensional metallic and semimetallic nanowires with a small number of conducting channels are proposed. Temperature enhancement of magnetotransport in such wires is predicted. Thermoelectric properties of nanowires in a magnetic field are studied. Magnetic splitting of thermopower peaks associated with electronic energy levels which are degenerate at zero field, leading to the development of separate thermopower peaks at larger fields, are predicted. A method for numerical calculation of the conductance through microconstrictions based on the time-dependent Schrodinger equation is developed, allowing investigations of electronic transport in complex situations. An algorithm for conductance calculations via propagation of wave packets is presented, and results for electronic transport through various constrictions are given, including model calculations of the conductance of a one-atom contact in the scanning tunneling microscope.

Scherbakov, Andrew Germanovich

358

Lietuvos teritorijos žem?s plutos deformacij? ir seismotektoninio potencialo ryšys  

NASA Astrophysics Data System (ADS)

Lietuvoje yra statini?, kelian?i? ekologinio pavojaus gr?sm? (Ignalinos atomin? elektrin?, Mažeiki? naftos perdirbimo ?mon?, chemijos gamyklos Jonavoje bei K?dainiuose ir pan.). Seisminiai ?vykiai gali sutrikdyti ši? ?moni? veikl? ir net lemti didel? pavoj? aplinkai, t. y. gali b?ti sukelta didel? aplinkos tarša chemin?mis bei radioaktyviosiomis medžiagomis. Seisminius ?vykius lemia teritorijos seismotektoninis potencialas. Seismotektoninis potencialas ir Žem?s plutos deformacijos yra tarpusavyje susij? rei\\vskiniai, kuriuos sukelia dažnai tie patys giluminiai procesai Žem?s gelm?se. Žem?s plutos deformacij? tyrimas yra vienas iš informacijos šaltini? prognozuojant teritorijos seismotektonin? aktyvum?. Straipsnyje nagrin?jamos Žem?s plutos horizontaliosios deformacijos, nustatomi Žem?s plutos ?tempi? poky?iai Lietuvos teritorijoje pagal GPS matavim? duomenis. Atlikus tyrimus pagal pateikiam? Žem?s plutos horizontali?j? deformacij? ir ?tempi? tyrimo metodik?, gauti nauji horizontali?j? deformacij? charakteristik? bei ?tempi? poky?i? rezultatai ir nustatytos j? s?sajos su seismotektoniniu potencialu.

Zakarevi?ius, Algimantas; Stanionis, Arminas; Levinskait?, Daiva

2010-01-01

359

7 CFR 1945.20 - Making EM loans available.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 false Making EM loans available. 1945.20 Section 1945.20 Agriculture Regulations of the Department...CONTINUED) EMERGENCY Disaster Assistance-General § 1945.20 Making EM loans available. EM...

2012-01-01

360

School Budget Hold'em Facilitator's Guide  

ERIC Educational Resources Information Center

"School Budget Hold'em" is a game designed to help school districts rethink their budgeting process. It evolved out of Education Resource Strategies' (ERS) experience working with large urban districts around the country. "School Budget Hold'em" offers a completely new approach--one that can turn the budgeting process into a long-term visioning…

Education Resource Strategies, 2012

2012-01-01

361

EMS communications development: History and commentary  

Microsoft Academic Search

The history of emergency medical services (EMS) communication systems development from the FCC's first allocation of frequencies for hospitals and ambulances up to the present is discussed. Up until the late 1960's EMS communication systems were virtually nonexistent. Most early networks were developed by hospital associations for coordination of hospital disaster operations. Many significant changes were seeded in 1966. By

B. A. Smith

1976-01-01

362

EM international activities. February 1997 highlights  

SciTech Connect

EM International Highlights is a brief summary of on-going international projects within the Department of Energy`s Office of Environmental Management (EM). This document contains sections on: Global Issues, activities in Western Europe, activities in central and Eastern Europe, activities in Russia, activities in Asia and the Pacific Rim, activities in South America, activities in North America, and International Organizations.

NONE

1997-02-01

363

Contributo para a caracterização molecular de echinococcus granulosus em Portugal.  

E-print Network

??Mestrado em Ciências Biomédicas, Especialidade de Biologia Molecular em Medicina Tropical e Internacional A Equinococose/hidatidose – doença causada pela fase larvar (hidátide – vulgarmente conhecida… (more)

Beato, Sílvia Filipa Alves

2008-01-01

364

Project X RFQ EM Design  

SciTech Connect

Project X is a proposed multi-MW proton facility at Fermi National Accelerator Laboratory (FNAL). The Project X front-end would consist of an H- ion source, a low-energy beam transport (LEBT), a CW 162.5 MHz radio-frequency quadrupole (RFQ) accelerator, and a medium-energy beam transport (MEBT). Lawrence Berkeley National Laboratory (LBNL) and FNAL collaboration is currently developing the designs for various components in the Project X front end. This paper reports the detailed EM design of the CW 162.5 MHz RFQ that provides bunching of the 1-10 mA H- beam with acceleration from 30 keV to 2.1 MeV.

Romanov, Gennady; /Fermilab; Hoff, Matthew; Li, Derun; Staples, John; Virostek, Steve; /LBNL

2012-05-09

365

EM International, July 1994, Volume 2  

SciTech Connect

The Office of Environmental Management (EM) at the Department of Energy (DOE) is seeking out and leveraging foreign technology, data, and resources in keeping with EM`s mandate to protect public health and the environment through the safe and cost-effective remediation of the Department`s nuclear weapons sites. EM works closely with foreign governments, industry, and universities to obtain innovative environmental technologies, scientific and engineering expertise, and operations experience that will support EM`s objectives. Where appropriate, these international resources are used to manage the more urgent risks at our sites, secure a safe workplace, help build consensus on critical issues, and strengthen our technology development program. Through international agreements EM engages in cooperative exchange of information, technology, and individuals. Currently, we are managing agreements with a dozen countries in Europe, Latin America, and Asia. These agreements focus on environmental restoration, waste management, transportation of radioactive wastes, and decontamination and decommissioning. This publication contains the following articles: in situ remediation integrated program; in-situ characterization and inspection of tanks; multimedia environmental pollutant assessment system (MEPAS); LLNL wet oxidation -- AEA technology. Besides these articles, this publication covers: EU activities with Russia; technology transfer activities; and international organization activities.

Not Available

1994-10-01

366

Light from cosmic strings  

SciTech Connect

The time-dependent metric of a cosmic string leads to an effective interaction between the string and photons--the ''gravitational Aharonov-Bohm'' effect--and causes cosmic strings to emit light. We evaluate the radiation of pairs of photons from cosmic strings and find that the emission from cusps, kinks and kink-kink collisions occurs with a flat spectrum at all frequencies up to the string scale. Further, cusps emit a beam of photons, kinks emit along a curve, and the emission at a kink-kink collision is in all directions. The emission of light from cosmic strings could provide an important new observational signature of cosmic strings that is within reach of current experiments for a range of string tensions.

Steer, Daniele A.; Vachaspati, Tanmay [APC 10 rue Alice Domon et Leonie Duquet, 75205 Paris Cedex 13 (France); Physics Department, Arizona State University, Tempe, Arizona 85287 (United States)

2011-02-15

367

Cosmic strings in hidden sectors: 1. Radiation of standard model particles  

NASA Astrophysics Data System (ADS)

In hidden sector models with an extra U(1) gauge group, new fields can interact with the Standard Model only through gauge kinetic mixing and the Higgs portal. After the U(1) is spontaneously broken, these interactions couple the resultant cosmic strings to Standard Model particles. We calculate the spectrum of radiation emitted by these ``dark strings'' in the form of Higgs bosons, Z bosons, and Standard Model fermions assuming that string tension is above the TeV scale. We also calculate the scattering cross sections of Standard Model fermions on dark strings due to the Aharonov-Bohm interaction. These radiation and scattering calculations will be applied in a subsequent paper to study the cosmological evolution and observational signatures of dark strings.

Long, Andrew J.; Hyde, Jeffrey M.; Vachaspati, Tanmay

2014-09-01

368

Asymmetric transmission through a flux-controlled non-Hermitian scattering center  

E-print Network

We study the possibility of asymmetric transmission induced by a non-Hermitian scattering center embedded in a one-dimensional waveguide, motivated by the aim of realizing quantum diode in a non-Hermitian system. It is shown that a $\\mathcal{PT}$ symmetric non-Hermitian scattering center always has symmetric transmission although the dynamics within the isolated center can be unidirectional, especially at its exceptional point. We propose a concrete scheme based on a flux-controlled non-Hermitian scattering center, which comprises a non-Hermitian triangular ring threaded by an Aharonov-Bohm flux. The analytical solution shows that such a complex scattering center acts as a diode at the resonant energy level of the spectral singularity, exhibiting perfect unidirectionality of the transmission. The connections between the phenomena of the asymmetric transmission and reflectionless absorption are also discussed.

X. Q. Li; X. Z. Zhang; G. Zhang; Z. Song

2014-09-01

369

Fault-tolerant quantum computation  

E-print Network

The discovery of quantum error correction has greatly improved the long-term prospects for quantum computing technology. Encoded quantum information can be protected from errors that arise due to uncontrolled interactions with the environment, or due to imperfect implementations of quantum logical operations. Recovery from errors can work effectively even if occasional mistakes occur during the recovery procedure. Furthermore, encoded quantum information can be processed without serious propagation of errors. In principle, an arbitrarily long quantum computation can be performed reliably, provided that the average probability of error per gate is less than a certain critical value, the accuracy threshold. It may be possible to incorporate intrinsic fault tolerance into the design of quantum computing hardware, perhaps by invoking topological Aharonov-Bohm interactions to process quantum information.

John Preskill

1997-12-19

370

The Nonlocal Pancharatnam Phase in Two-Photon Interferometry  

E-print Network

The Pancharatnam phase was discovered in the context of amplitude interferometry of polarised light and anticipates Berry's discovery of the geometric phase. We propose a polarised intensity interferometry experiment which measures the nonlocal Pancharatnam phase acquired by a pair of Hanbury Brown-Twiss photons. The experimental setup involves two polarised thermal sources illuminating two polarised detectors. Varying the relative polarisation angle of the detectors introduces a geometric phase equal to half the solid angle traced out on the Poincare sphere by a pair of photons. Local measurements at either detector do not reveal the effects of the phase, which appears only in the coincidence counts of the two detectors and is a genuinely multiparticle and nonlocal effect. The phase is an optical analog of the multiparticle Aharonov-Bohm effect which has been measured in Quantum Hall systems.

Mehta, Poonam; Sinha, Supurna

2010-01-01

371

An Experimental Proposal to Test Dynamic Quantum Non-locality with Single-Atom Interferometry  

E-print Network

Quantum non-locality based on the well-known Bell inequality is of kinematic nature. A different type of quantum non-locality, the non-locality of the quantum equation of motion, is recently put forward with connection to the Aharonov-Bohm effect [Nature Phys. 6, 151 (2010)]. Evolution of the displacement operator provides an example to manifest such dynamic quantum non-locality. We propose an experiment using single-atom interferometry to test such dynamic quantum non-locality. We show how to measure evolution of the displacement operator with clod atoms in a spin-dependent optical lattice potential and discuss signature to identify dynamic quantum non-locality under a realistic experimental setting.

Zhu, Shi-Liang; Zhang, Dan-Wei; Duan, Lu-Ming

2010-01-01

372

Geometric phases for astigmatic optical modes of arbitrary order  

E-print Network

The transverse spatial structure of a basis set of paraxial optical modes is fully characterized by a set of parameters that vary only slowly under free propagation. The parameters specify bosonic ladder operators that connect modes of different order, in analogy to the ladder operators connecting harmonic-oscillator wave functions. The parameter spaces underlying closed subspaces of higher-order modes are carbon copies of the parameter space of the ladder operators. We study the geometry of this space and the geometric phase that arises from it. This phase constitutes the ultimate generalization of the Gouy phase in paraxial wave optics and we recover the ordinary Gouy phase shift and the geometric phase for optical orbital angular momentum states as limiting cases. We discuss an analogy with the Aharonov-Bohm effect that reveals some deep insights in the nature and origin of the generalized Gouy phase shift.

Habraken, Steven J M

2010-01-01

373

Exciton states and optical properties of carbon nanotubes.  

PubMed

Exciton states and related optical properties of a single-walled carbon nanotube are reviewed, primarily from a theoretical viewpoint. The energies and wavefunctions of excitons are discussed using a screened Hartree-Fock approximation with an effective-mass or k·p approximation. The close relationship between a long-range electron-hole exchange interaction and a depolarization effect is clarified. I discuss optical properties including the radiative lifetime of excitons, absorption spectra and radiation force. To describe these properties in a unified scheme, a self-consistent method is introduced for calculating the scattering light and induced current density due to excitons. I also briefly review experimental results on the Aharonov-Bohm effect in excitons and quasi-dark excitons excited by light polarized perpendicular to the tube axis. PMID:23139202

Ajiki, Hiroshi

2012-12-01

374

Space-time description of transverse photons: near-field aspects  

NASA Astrophysics Data System (ADS)

A mean position state based on the gauge invariant transverse vector potential is used to convert single-photon states in Hilbert space to photon wave packets in direct space. The resulting photon wave-mechanical description leads to scalar products which relate to covariant integration on the light cone. A new correlation matrix displays the spatial localization problem for single photons in an explicit manner in space-time. The correlation matrix essentially is the projection of the time-ordered Feynman photon propagator onto the transverse photon subspace. The present photon wave-mechanical formalism is generalized to two-photon dynamics. In the diamagnetic limit the transverse photon becomes massive in its interaction with matter, and the correlation matrix for massive-photon interaction, which can be used in studies of evanescent-photon mediated couplings, is analyzed. On the basis of the present formalism the existence of a dynamical near-field Aharonov-Bohm effect is predicted.

Keller, O.

2012-08-01

375

Transport properties of two finite armchair graphene nanoribbons  

PubMed Central

In this work, we present a theoretical study of the transport properties of two finite and parallel armchair graphene nanoribbons connected to two semi-infinite leads of the same material. Using a single ?-band tight binding Hamiltonian and based on Green’s function formalisms within a real space renormalization techniques, we have calculated the density of states and the conductance of these systems considering the effects of the geometric confinement and the presence of a uniform magnetic field applied perpendicularly to the heterostructure. Our results exhibit a resonant tunneling behaviour and periodic modulations of the transport properties as a function of the geometry of the considered conductors and as a function of the magnetic flux that crosses the heterostructure. We have observed Aharonov-Bohm type of interference representing by periodic metal-semiconductor transitions in the DOS and conductance curves of the nanostructures. PMID:23279756

2013-01-01

376

Experimental realization of strong effective magnetic fields in an optical lattice  

E-print Network

We use Raman-assisted tunneling in an optical superlattice to generate large tunable effective magnetic fields for ultracold atoms. When hopping in the lattice, the accumulated phase shift by an atom is equivalent to the Aharonov-Bohm phase of a charged particle exposed to a staggered magnetic field of large magnitude, on the order of one flux quantum per plaquette. We study the ground state of this system and observe that the frustration induced by the magnetic field can lead to a degenerate ground state for non-interacting particles. We provide a measurement of the local phase acquired from Raman-induced tunneling, demonstrating time-reversal symmetry breaking of the underlying Hamiltonian. Furthermore, the quantum cyclotron orbit of single atoms in the lattice exposed to the magnetic field is directly revealed.

Aidelsburger, Monika; Nascimbène, Sylvain; Trotzky, Stefan; Chen, Yu-Ao; Bloch, Immanuel

2011-01-01

377

Coherent magneto-optical activity in a single chiral carbon nanotube  

NASA Astrophysics Data System (ADS)

We propose a theoretical framework and dynamical model for description of the natural optical activity and Faraday rotation in an individual chiral singlewalled carbon nanotube in the highly nonlinear coherent regime. The model is based on a discrete-level representation of the optically active states near the band edge. Chirality is modeled by a system Hamiltonian in a four-level basis corresponding to energy-level configurations, specific for each handedness, that are mirror reflections of each other. The axial magnetic field is introduced through the Aharonov-Bohm and Zeeman energy-level shifts. The time evolution of the quantum system, describing a single nanotube with defined chirality, under un ultrashort polarised pulse excitation is studied using the coupled coherent vector Maxwell-pseudospin equations [Ref.[34

Slavcheva, Gabriela; Roussignol, Philippe

378

Quantum dynamics of magnetically controlled network for Bloch electrons  

E-print Network

We study quantum dynamics of wave packet motion of Bloch electrons in quantum networks with the tight-binding approach for different types of nearest-neighbor interactions. For various geometrical configurations, these networks can function as some optical devices, such as beam splitters and interferometers. When the Bloch electrons with the Gaussian wave packets input these devices, various quantum coherence phenomena can be observed, e.g., the perfect quantum state transfer without reflection in a Y-shaped beam, the multi- mode entanglers of electron wave by star shaped network and Bloch electron interferometer with the lattice Aharonov-Bohm effects. Behind these conceptual quantum devices are the physical mechanism that, for hopping parameters with some specific values, a connected quantum networks can be reduced into a virtual network, which is a direct sum of some irreducible subnetworks. Thus, the perfect quantum state transfer in each subnetwork in this virtual network can be regarded as a coherent bea...

Yang, S; Sun, C P

2006-01-01

379

Polaritonic devices  

NASA Astrophysics Data System (ADS)

We review the current hopes for applications of exciton-polaritons in semiconductor microcavities. These quasi-particles have become distinguished in recent years for a variety of different effects including Bose-Einstein condensation, ballistic spin current propagation and polarisation sensitive bistability. Bose-Einstein condensation is related to ultra low-threshold lasing, which has been demonstrated at room temperature and currently captures a significant research effort towards electrical carrier injection. Inspired by spintronics, the spin structure of polaritons gives rise to the field of spinoptronics, which presents optical analogues of the Datta and Das transistor and Aharonov-Bohm ring interferometer. Bistability, enhanced with the polarisation degree of freedom, gives rise to long-living spin memory elements, spin logic gates and polariton neurons for the construction of all-optical and hybrid optoelectronic circuits.

Liew, T. C. H.; Shelykh, I. A.; Malpuech, G.

2011-07-01

380

Confined electronic states and their modulations in graphene nanorings  

NASA Astrophysics Data System (ADS)

Confined electronic states in quantum rings formed by spatially modulated finite Dirac gap (FDGQR) in graphene are systematically studied by series-expansion method, and are compared with those in infinite-mass-boundary and one-dimensional quantum rings. The shape-size effect of FDGQR is illustrated to be distinct from that in graphene quantum dots. The Aharonov-Bohm effect in FDGQR is clearly shown by the energy spectrum and the optical-transition probabilities. The FDGQR coupled with the electrostatic-potential induced nanoring is found useful for modulating the Dirac electronic states and the optical-transition probabilities. These results may help us to understand and to control the quantum behaviors of confined electronic states in graphene.

Zhu, Jia-Lin; Wang, Xingyuan; Yang, Ning

2012-09-01

381

Realization of the Hofstadter Hamiltonian with ultracold atoms in optical lattices.  

PubMed

We demonstrate the experimental implementation of an optical lattice that allows for the generation of large homogeneous and tunable artificial magnetic fields with ultracold atoms. Using laser-assisted tunneling in a tilted optical potential, we engineer spatially dependent complex tunneling amplitudes. Thereby, atoms hopping in the lattice accumulate a phase shift equivalent to the Aharonov-Bohm phase of charged particles in a magnetic field. We determine the local distribution of fluxes through the observation of cyclotron orbits of the atoms on lattice plaquettes, showing that the system is described by the Hofstadter model. Furthermore, we show that for two atomic spin states with opposite magnetic moments, our system naturally realizes the time-reversal-symmetric Hamiltonian underlying the quantum spin Hall effect; i.e., two different spin components experience opposite directions of the magnetic field. PMID:24237530

Aidelsburger, M; Atala, M; Lohse, M; Barreiro, J T; Paredes, B; Bloch, I

2013-11-01

382

Unexpected behavior in a two-path electron interferometer.  

PubMed

We report the observation of an unpredictable behavior of a simple, two-path, electron interferometer. Utilizing an electronic analog of the well-known optical Mach-Zehnder interferometer, with current carrying edge channels in the quantum Hall effect regime, we measured high contrast Aharonov-Bohm (AB) oscillations. Surprisingly, the amplitude of the oscillations varied with energy in a lobe fashion, namely, with distinct maxima and zeros (namely, no AB oscillations) in between. Moreover, the phase of the AB oscillations was constant throughout each lobe period but slipped abruptly by pi at each zero. The periodicity of the lobes defines a new energy scale, which may be a general characteristic of quantum coherence of interfering electrons. PMID:16486497

Neder, I; Heiblum, M; Levinson, Y; Mahalu, D; Umansky, V

2006-01-13

383

Control of tripod-scheme cold-atom wavepackets by manipulating a non-Abelian vector potential  

NASA Astrophysics Data System (ADS)

Tripod-scheme cold atoms interacting with laser beams have attracted considerable interest for their role in synthesizing effective non-Abelian vector potentials. Such effective vector potentials can be exploited to realize an all-optical imprinting of geometric phases onto matter waves. By working on carefully designed extensions of our previous work, we show that coherent lattice structure of cold-atom sub-wavepackets can be formed and that the non-Abelian Aharonov-Bohm effect can be easily manifested via the translational motion of cold atoms. We also show that by changing the frame of reference, effects due to a non-Abelian vector potential may be connected with a simple dynamical phase effect, and that under certain conditions it can be understood as an Abelian geometric phase in a different frame of reference. Results should help design better schemes for the control of cold-atom matter waves.

Zhang, Qi; Gong, Jiangbin; Oh, C. H.

2010-06-01

384

An experimental proposal to test dynamic quantum non-locality with single-atom interferometry  

NASA Astrophysics Data System (ADS)

Quantum non-locality based on the well-known Bell inequality is of kinematic nature. A different type of quantum non-locality, the non-locality of the quantum equation of motion, is recently put forward with connection to the Aharonov-Bohm effect (Popescu S., Nat. Phys., 6 (2010) 151). Evolution of the displacement operator provides an example to manifest such dynamic quantum non-locality. We propose an experiment using single-atom interferometry to test such dynamic quantum non-locality. We show how to measure evolution of the displacement operator with cold atoms in a spin-dependent optical lattice potential and discuss signature to identify dynamic quantum non-locality under a realistic experimental setting.

Zhu, Shi-Liang; Xue, Zheng-Yuan; Zhang, Dan-Wei; Duan, Lu-Ming

2011-06-01

385

Realization of the Hofstadter Hamiltonian with Ultracold Atoms in Optical Lattices  

NASA Astrophysics Data System (ADS)

We demonstrate the experimental implementation of an optical lattice that allows for the generation of large homogeneous and tunable artificial magnetic fields with ultracold atoms. Using laser-assisted tunneling in a tilted optical potential, we engineer spatially dependent complex tunneling amplitudes. Thereby, atoms hopping in the lattice accumulate a phase shift equivalent to the Aharonov-Bohm phase of charged particles in a magnetic field. We determine the local distribution of fluxes through the observation of cyclotron orbits of the atoms on lattice plaquettes, showing that the system is described by the Hofstadter model. Furthermore, we show that for two atomic spin states with opposite magnetic moments, our system naturally realizes the time-reversal-symmetric Hamiltonian underlying the quantum spin Hall effect; i.e., two different spin components experience opposite directions of the magnetic field.

Aidelsburger, M.; Atala, M.; Lohse, M.; Barreiro, J. T.; Paredes, B.; Bloch, I.

2013-11-01

386

Experimental Realization of Strong Effective Magnetic Fields in an Optical Lattice  

SciTech Connect

We use Raman-assisted tunneling in an optical superlattice to generate large tunable effective magnetic fields for ultracold atoms. When hopping in the lattice, the accumulated phase shift by an atom is equivalent to the Aharonov-Bohm phase of a charged particle exposed to a staggered magnetic field of large magnitude, on the order of 1 flux quantum per plaquette. We study the ground state of this system and observe that the frustration induced by the magnetic field can lead to a degenerate ground state for noninteracting particles. We provide a measurement of the local phase acquired from Raman-induced tunneling, demonstrating time-reversal symmetry breaking of the underlying Hamiltonian. Furthermore, the quantum cyclotron orbit of single atoms in the lattice exposed to the magnetic field is directly revealed.

Aidelsburger, M.; Atala, M.; Trotzky, S.; Chen, Y.-A.; Bloch, I. [Fakultaet fuer Physik, Ludwig-Maximilians-Universitaet, Schellingstrasse 4, 80799 Muenchen (Germany); Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching (Germany); Nascimbene, S. [Fakultaet fuer Physik, Ludwig-Maximilians-Universitaet, Schellingstrasse 4, 80799 Muenchen (Germany); Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching (Germany); Laboratoire Kastler Brossel, CNRS, UPMC, Ecole Normale Superieure, 24 rue Lhomond, 75005 Paris (France)

2011-12-16

387

Effect of an electric field on the nonlinear optical rectification of a quantum ring  

NASA Astrophysics Data System (ADS)

We have studied the effects of an external electric field on the nonlinear optical rectification of a semiconductor quantum ring. An electric field applied in the ring plane destroys the rotational invariance. Calculations are performed by using the matrix diagonalization method and the compact density-matrix approach within the effective-mass approximation. The results indicate that an increase of electric field gives the red shift of the peak positions of nonlinear optical rectification. The roles of ring size and magnetic field strength as control parameters on this nonlinear property have been investigated. Our results show rich nonlinear optical rectification for quantum rings in the presence of electric fields, which effectively displays the signature of the Aharonov-Bohm oscillation.

Xie, Wenfang

2014-06-01

388

Magnetic monopole field exposed by electrons  

E-print Network

Magnetic monopoles have provided a rich field of study, leading to a wide area of research in particle physics, solid state physics, ultra-cold gases, superconductors, cosmology, and gauge theory. So far, no true magnetic monopoles were found experimentally. Using the Aharonov-Bohm effect, one of the central results of quantum physics, shows however, that an effective monopole field can be produced. Understanding the effects of such a monopole field on its surroundings is crucial to its observation and provides a better grasp of fundamental physical theory. We realize the diffraction of fast electrons at a magnetic monopole field generated by a nanoscopic magnetized ferromagnetic needle. Previous studies have been limited to theoretical semiclassical optical calculations of the motion of electrons in such a monopole field. Solid state systems like the recently studied 'spin ice' provide a constrained system to study similar fields, but make it impossible to separate the monopole from the material. Free space ...

Béché, A; Van Tendeloo, G; Verbeeck, J

2013-01-01

389

Magnetoluminescence from trion and biexciton in type-II quantum dot  

NASA Astrophysics Data System (ADS)

We theoretically investigate optical Aharonov-Bohm (AB) effects on trion and biexciton in the type-II semiconductor quantum dots, in which holes are localized near the center of the dot, and electrons are confined in a ring structure formed around the dot. Many-particle states are calculated numerically by the exact diagonalization method. Two electrons in trion and biexciton are strongly correlated to each other, forming a Wigner molecule. Since the relative motion of electrons are frozen, the Wigner molecule behaves as a composite particle whose mass and charges are twice those of an electron. As a result, the period of AB oscillation for trion and biexciton becomes h/2 e as a function of magnetic flux penetrating the ring. We find that the magnetoluminescence spectra from trion and biexciton change discontinuously as the magnetic flux increases by h/2 e. PACS: 71.35.Ji, 73.21.-b, 73.21.La, 78.67.Hc

Okuyama, Rin; Eto, Mikio; Hyuga, Hiroyuki

2011-04-01

390

Artificial gauge potentials for neutral atoms  

E-print Network

When a neutral atom moves in a properly designed laser field, its center-of-mass motion may mimic the dynamics of a charged particle in a magnetic field, with the emergence of a Lorentz-like force. In this Colloquium we present the physical principles at the basis of this artificial (synthetic) magnetism and relate the corresponding Aharonov-Bohm phase to the Berry's phase that emerges when the atom follows adiabatically one of its dressed states. We also discuss some manifestations of artificial magnetism for a cold quantum gas, in particular in terms of vortex nucleation. We then generalise our analysis to the simulation of non-Abelian gauge potentials and present some striking consequences, such as the emergence of an effective spin-orbit coupling. We address both the case of bulk gases and discrete systems, where atoms are trapped in an optical lattice.

Dalibard, Jean; Juzeli?nas, Gediminas; Öhberg, Patrik

2010-01-01

391

Experimental Realization of Strong Effective Magnetic Fields in an Optical Lattice  

NASA Astrophysics Data System (ADS)

We use Raman-assisted tunneling in an optical superlattice to generate large tunable effective magnetic fields for ultracold atoms. When hopping in the lattice, the accumulated phase shift by an atom is equivalent to the Aharonov-Bohm phase of a charged particle exposed to a staggered magnetic field of large magnitude, on the order of 1 flux quantum per plaquette. We study the ground state of this system and observe that the frustration induced by the magnetic field can lead to a degenerate ground state for noninteracting particles. We provide a measurement of the local phase acquired from Raman-induced tunneling, demonstrating time-reversal symmetry breaking of the underlying Hamiltonian. Furthermore, the quantum cyclotron orbit of single atoms in the lattice exposed to the magnetic field is directly revealed.

Aidelsburger, M.; Atala, M.; Nascimbène, S.; Trotzky, S.; Chen, Y.-A.; Bloch, I.

2011-12-01

392

Excitonic behavior in self-assembled InAs/GaAs quantum rings in high magnetic fields  

NASA Astrophysics Data System (ADS)

We investigate the exciton energy level structure of a large ensemble of InAs/GaAs quantum rings by photoluminescence spectroscopy in magnetic fields up to 30 T for different excitation densities. The confinement of an electron and a hole in these type I quantum rings along with the Coulomb interaction suppress the excitonic Aharonov-Bohm effect. We show that the exciton energy levels are nonequidistant and split up in only two levels in magnetic field, reflecting the ringlike geometry. A model, based on realistic parameters of the self-assembled quantum rings, allows us to interpret the essential features of the observed PL spectra in terms of the calculated optical transition probabilities.

Kleemans, N. A. J. M.; Blokland, J. H.; Taboada, A. G.; van Genuchten, H. C. M.; Bozkurt, M.; Fomin, V. M.; Gladilin, V. N.; Granados, D.; García, J. M.; Christianen, P. C. M.; Maan, J. C.; Devreese, J. T.; Koenraad, P. M.

2009-10-01

393

A Novel Cavity-Based Atom Interferometer  

NASA Astrophysics Data System (ADS)

The world's leading atom interferometers are housed in bulky atomic fountains. They employ a variety of techniques to increase the spatial separation between atomic clouds including high order Bragg diffraction. The largest momentum transfer in a single Bragg beamsplitter has been limited to 24 k by laser power and beam quality. We present an atom interferometer in a 40 cm optical cavity to enhance the available laser power, minimize wavefront distortions, and control other systematic effects symptomatic to atomic fountains. We expect to achieve spatial separations between atomic trajectories comparable to larger scale fountains within a more compact device. We report on our progress in developing this new interferometer using cold Cs atoms and discuss its prospects for exploring large momentum transfer up to 100 k in a single Bragg diffraction process. The compact design will enable the first demonstration of the gravitostatic Aharonov-Bohm effect.

Brown, Justin; Estey, Brian; Müller, Holger

2012-06-01

394

Colloquium: Artificial gauge potentials for neutral atoms  

NASA Astrophysics Data System (ADS)

When a neutral atom moves in a properly designed laser field, its center-of-mass motion may mimic the dynamics of a charged particle in a magnetic field, with the emergence of a Lorentz-like force. In this Colloquium the physical principles at the basis of this artificial (synthetic) magnetism are presented. The corresponding Aharonov-Bohm phase is related to the Berry’s phase that emerges when the atom adiabatically follows one of the dressed states of the atom-laser interaction. Some manifestations of artificial magnetism for a cold quantum gas, in particular, in terms of vortex nucleation are discussed. The analysis is then generalized to the simulation of non-Abelian gauge potentials and some striking consequences are presented, such as the emergence of an effective spin-orbit coupling. Both the cases of bulk gases and discrete systems, where atoms are trapped in an optical lattice, are addressed.

Dalibard, Jean; Gerbier, Fabrice; Juzeli?nas, Gediminas; Öhberg, Patrik

2011-10-01

395

Control of tripod-scheme cold-atom wavepackets by manipulating a non-Abelian vector potential  

SciTech Connect

Tripod-scheme cold atoms interacting with laser beams have attracted considerable interest for their role in synthesizing effective non-Abelian vector potentials. Such effective vector potentials can be exploited to realize an all-optical imprinting of geometric phases onto matter waves. By working on carefully designed extensions of our previous work, we show that coherent lattice structure of cold-atom sub-wavepackets can be formed and that the non-Abelian Aharonov-Bohm effect can be easily manifested via the translational motion of cold atoms. We also show that by changing the frame of reference, effects due to a non-Abelian vector potential may be connected with a simple dynamical phase effect, and that under certain conditions it can be understood as an Abelian geometric phase in a different frame of reference. Results should help design better schemes for the control of cold-atom matter waves.

Zhang Qi, E-mail: cqtzq@nus.edu.s [Centre of Quantum Technologies and Department of Physics, National University of Singapore, 117543 (Singapore); Gong Jiangbin, E-mail: phygj@nus.edu.s [Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, 117542 (Singapore); NUS Graduate School for Integrative Sciences and Engineering, Singapore 117597 (Singapore); Oh, C.H., E-mail: phyohch@nus.edu.s [Centre of Quantum Technologies and Department of Physics, National University of Singapore, 117543 (Singapore); Institute of Advanced Studies, Nanyang Technological University, Singapore 639798 (Singapore)

2010-06-15

396

Exciton states and optical properties of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Exciton states and related optical properties of a single-walled carbon nanotube are reviewed, primarily from a theoretical viewpoint. The energies and wavefunctions of excitons are discussed using a screened Hartree-Fock approximation with an effective-mass or k ?p approximation. The close relationship between a long-range electron-hole exchange interaction and a depolarization effect is clarified. I discuss optical properties including the radiative lifetime of excitons, absorption spectra and radiation force. To describe these properties in a unified scheme, a self-consistent method is introduced for calculating the scattering light and induced current density due to excitons. I also briefly review experimental results on the Aharonov-Bohm effect in excitons and quasi-dark excitons excited by light polarized perpendicular to the tube axis.

Ajiki, Hiroshi

2012-12-01

397

Beyond the constant-mass Dirac physics: Solitons, charge fractionization, and the emergence of topological insulators in graphene rings  

E-print Network

The doubly-connected polygonal geometry of planar graphene rings is found to bring forth topological configurations for accessing nontrivial relativistic quantum field (RQF) theory models that carry beyond the constant-mass Dirac-fermion theory. These include generation of sign-alternating masses, solitonic excitations, and charge fractionization. The work integrates a RQF Lagrangian formulation with numerical tight-binding Aharonov-Bohm electronic spectra and the generalized position-dependent-mass Dirac equation. In contrast to armchair graphene rings (aGRGs) with pure metallic arms, certain classes of aGRGs with semiconducting arms, as well as with mixed metallic-semiconducting ones, are shown to exhibit properties of one-dimensional nontrivial topological insulators. This further reveals an alternative direction for realizing a graphene-based nontrivial topological insulator through the manipulation of the honeycomb lattice geometry, without a spin-orbit contribution.

Constantine Yannouleas; Igor Romanovsky; Uzi Landman

2014-01-22

398

Biprism Electron Interferometry with a Single Atom Tip Source  

E-print Network

Experiments with electron or ion matter waves require a coherent, monochromatic and long-term stable source with high brightness. These requirements are best fulfilled by single atom tip (SAT) field emitters. The performance of an iridium covered W(111) SAT is demonstrated and analyzed for electrons in a biprism interferometer. Furthermore we characterize the emission of the SAT in a separate field electron and field ion microscope and compare it with other emitter types. A new method is presented to fabricate the electrostatic charged biprism wire that separates and combines the matter wave. In contrast to other biprism interferometers the source and the biprism size are well defined within a few nanometers. The setup has direct applications in ion interferometry and Aharonov-Bohm physics.

Georg Schütz; Alexander Rembold; Andreas Pooch; Simon Meier; Philipp Schneeweiss; Arno Rauschenbeutel; Andreas Günther; Wei-Tse Chang; Ing-Shouh Hwang; Alexander Stibor

2013-11-28

399

Engineering massive quantum memories by topologically time-modulated spin rings  

E-print Network

We introduce a general scheme to realize perfect storage of quantum information in systems of interacting qubits. This novel approach is based on {\\it global} external controls of the Hamiltonian, that yield time-periodic inversions in the dynamical evolution, allowing a perfect periodic quantum state recontruction. We illustrate the method in the particularly interesting and simple case of spin systems affected by XY residual interactions with or without static imperfections. The global control is achieved by step time-inversions of an overall topological phase of the Aharonov-Bohm type. Such a scheme holds both at finite size and in the thermodynamic limit, thus enabling the massive storage of arbitrarily large numbers of local states, and is stable against several realistic sources of noise and imperfections.

S. M. Giampaolo; F. Illuminati; A. Di Lisi; S. De Siena

2005-03-10

400

Is Quantum Mechanics Incompatible with Newton's First Law  

E-print Network

Quantum mechanics (QM) clearly violates Newton's First Law of Motion (NFLM) in the quantum domain for one of the simplest problems, yielding an effect in a force-free region much like the Aharonov-Bohm effect. In addition, there is an incompatibility between the predictions of QM in the classical limit, and that of classical mechanics (CM) with respect to NFLM. A general argument is made that such a disparity may be found commonly for a wide variety of quantum predictions in the classical limit. Alternatives to the Schrodinger equation are considered that might avoid this problem. The meaning of the classical limit is examined. Critical views regarding QM by Schrodinger, Bohm, Bell, Clauser, and others are presented to provide a more complete perspective.

Mario Rabinowitz

2007-05-30

401

Quantum and Classical Variance in the Quantum Realm  

E-print Network

This paper examines the variance of quantum and classical predictions in the quantum realm, as well as unexpected presence and absence of variances. Some features are found that share an indirect commonality with the Aharonov-Bohm and Aharonov-Casher effects in that there is a quantum action in the absence of a force. Variances are also found in the presence of a force that are more subtle as they are of higher order. Significant variances related to the harmonic oscillator and particle in a box periods are found. This paper raises the question whether apparent quantum self-inconsistency may be examined internally, or must be empirically ascertained. These inherent variances may either point to inconsistencies in quantum mechanics that should be fixed, or that nature is manifestly more non-classical than expected. For the harmonic oscillator it is proven that the second spatial moment is the same in QM and CM.

Mario Rabinowitz

2007-07-08

402

Completeness for coherent states in a magnetic-solenoid field  

NASA Astrophysics Data System (ADS)

This paper completes our study of coherent states in the so-called magnetic-solenoid field (a collinear combination of a constant uniform magnetic field and Aharonov-Bohm solenoid field) presented in Bagrov et al (2010 J. Phys. A: Math. Theor. 43 354016, 2011 J. Phys. A: Math. Theor. 44 055301). Here, we succeeded in proving nontrivial completeness relations for non-relativistic and relativistic coherent states in such a field. In addition, we solve here the relevant Stieltjes moment problem and present a comparative analysis of our coherent states and the well-known, in the case of pure uniform magnetic field, Malkin-Man’ko coherent states. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Coherent states: mathematical and physical aspects’.

Bagrov, V. G.; Gavrilov, S. P.; Gitman, D. M.; Górska, K.

2012-06-01

403

The Physical Interpretation of the Lanczos Tensor  

E-print Network

The field equations of general relativity can be written as first order differential equations in the Weyl tensor, the Weyl tensor in turn can be written as a first order differential equation in a three index tensor called the Lanczos tensor. The Lanczos tensor plays a similar role in general relativity to that of the vector potential in electro-magnetic theory. The Aharonov-Bohm effect shows that when quantum mechanics is applied to electro-magnetic theory the vector potential is dynamically significant, even when the electro-magnetic field tensor $F_{ab}$ vanishes. Here it is assumed that in the quantum realm the Lanczos tensor is dynamically significant, and this leads to an attempt to quantize the gravitational field by pursuing the analogy between the vector field and the Lanczos tensor.

Mark D. Roberts

1999-04-04

404

Two-electron volcano-shaped quantum dot  

NASA Astrophysics Data System (ADS)

We propose a simple model of non-uniform volcano-shaped quantum dot that reflects the confinement details of the morphology of really fabricated GaAs/InAs nanorings and whose profile geometry, on the one hand, is described by means of simple analytical functions and, on the other hand, allows us to find exact one-particle wave functions. By using them as a basis function we calculate two-electron lower energies as functions of the external magnetic field applied along the growth axis. We show that the ring morphology and electron-electron interaction have great influence on the energy spectrum structure of nanoring and the Aharonov-Bohm oscillations.

Garcia, L. F.; Gutiérrez, W.; Mikhailov, I. D.

2014-12-01

405

Geometrically induced electric polarization in conical topological insulators  

E-print Network

We study the topological magnetoelectric effect on a conical topological insulator when a point charge $q$ is near the cone apex. The Hall current induced on the cone surface and the image charge configuration are determined. We also study a kind of gravitational Aharonov-Bohm effect in this geometry and realize a phase diference betwen the components of the wavefunctions (spinors) upon closed parallel transport around the (singular) cone tip. Concretely, a net current flowing towards cone apex (or botton) shows up, yielding electric polarization of the conical topological insulator. Such an effect may be detected, for instance, by means of the net accumulated Hall charge near the apex. Once it depends only on the geometry of the material (essetially, the cone apperture angle) this may be faced as a microscopic scale realization of (2+1)-dimensional Einstein gravity.

Jakson M. Fonseca; Winder A. Moura-Melo; Afranio R. Pereira

2011-11-29

406

Gauge Theory and Artificial Spin Ices: Imaging Emergent Monopoles with Electron Microscopy  

NASA Astrophysics Data System (ADS)

Since it was proposed, the Aharonov-Bohm (AB) effect has sparked profound debate on the nature of gauge fields in physics and offered the possibility for experimental proof for gauge theories. Proof of the AB effect, essential evidence for the theory of gauge fields, was given by Tonomura in his seminal work on the subject. In this article, we discuss its relation to the Dirac monopole and string. Furthermore, we utilize it to experimentally study emergent monopoles and flux channels in the condensed matter setting of artificial spin ices. We use phase imaging based on the AB effect to study ordering processes in the spin ice lattice during magnetic reversal and the effect that emergent monopoles and flux channels have on this reversal. We observe that monopole interactions govern defect densities within the spin lattice, and exploit these interactions to develop at a new method to achieve high degrees of ground state ordering in a frustrated system.

Pollard, Shawn D.; Zhu, Yimei

2014-01-01

407

Conductance maps of quantum rings due to a local potential perturbation  

NASA Astrophysics Data System (ADS)

We performed a numerical simulation of the dynamics of a Gaussian shaped wavepacket inside a small sized quantum ring, smoothly connected to two leads and exposed to a perturbing potential of a biased atomic force microscope tip. Using the Landauer formalism, we calculated conductance maps of this system in the case of single and two subband transport. We explain the main features in the conductance maps as due to the AFM tip influence on the wavepacket phase and amplitude. In the presence of an external magnetic field, the tip modifies the ?0 periodic Aharonov-Bohm oscillation pattern into a ?0/2 periodic Al’tshuler-Aronov-Spivak oscillation pattern. Our results in the case of multiband transport suggest tip selectivity to higher subbands, making them more observable in the total conductance map.

Petrovi?, M. D.; Peeters, F. M.; Chaves, A.; Farias, G. A.

2013-12-01

408

Possible latitude effects of Chern-Simons gravity on quantum interference  

NASA Astrophysics Data System (ADS)

It has been recently suggested that, as a gravitational Aharonov-Bohm effect due to a gravitomagnetic potential, possible effects of Chern-Simons gravity on a quantum interferometer are dependent on the latitude and direction of the interferometer on Earth in orbital motion around the Sun. Continuing work initiated in an earlier publication [H. Okawara, K. Yamada, and H. Asada, Phys. Rev. Lett. 109, 231101 (2012)], we perform numerical calculations of time variation in the induced phase shifts for nonequatorial cases. We show that the maximum phase shift at any latitude might occur at 6, 0 (and 12), and 18 hours (in local time) of each day, when the normal vector to the interferometer is vertical, eastbound, and northbound, respectively. If two identical interferometers were located at different latitudes, the difference between two phase shifts measured at the same local time would be O(sin???) for a small latitude difference ??. It might thus become maximally ˜20% for ??˜10°, for instance.

Okawara, Hiroki; Yamada, Kei; Asada, Hideki

2013-04-01

409

Optical conductivity of curved graphene  

E-print Network

We compute the optical conductivity for an out-of-plane deformation in graphene using an approach based on solutions of the Dirac equation in curved space. Different examples of periodic deformations along one direction translates into an enhancement of the optical conductivity peaks in the region of the far and mid infrared frequencies for periodicities $\\sim100\\,$nm. The width and position of the peaks can be changed by dialling the parameters of the deformation profiles. The enhancement of the optical conductivity is due to intraband transitions and the translational invariance breaking in the geometrically deformed background. Furthemore, we derive an analytical solution of the Dirac equation in a curved space for a general deformation along one spatial direction. For this class of geometries, it is shown that curvature induces an extra phase in the electron wave function, which can also be explored to produce interference devices of the Aharonov-Bohm type.

A. J. Chaves; T. Frederico; O. Oliveira; W. de Paula; M. C. Santos

2013-10-09

410

Optical conductivity of curved graphene  

E-print Network

We compute the optical conductivity for an out-of-plane deformation in graphene using an approach based on solutions of the Dirac equation in curved space. Different examples of periodic deformations along one direction translates into an enhancement of the optical conductivity peaks in the region of the far and mid infrared frequencies for periodicities $\\sim100\\,$nm. The width and position of the peaks can be changed by dialling the parameters of the deformation profiles. The enhancement of the optical conductivity is due to intraband transitions and the translational invariance breaking in the geometrically deformed background. Furthemore, we derive an analytical solution of the Dirac equation in a curved space for a general deformation along one spatial direction. For this class of geometries, it is shown that curvature induces an extra phase in the electron wave function, which can also be explored to produce interference devices of the Aharonov-Bohm type.

Chaves, A J; Oliveira, O; de Paula, W; Santos, M C

2014-01-01

411

Topologically protected excitons in porphyrin thin films  

NASA Astrophysics Data System (ADS)

The control of exciton transport in organic materials is of fundamental importance for the development of efficient light-harvesting systems. This transport is easily deteriorated by traps in the disordered energy landscape. Here, we propose and analyse a system that supports topological Frenkel exciton edge states. Backscattering of these chiral Frenkel excitons is prohibited by symmetry, ensuring that the transport properties of such a system are robust against disorder. To implement our idea, we propose a two-dimensional periodic array of tilted porphyrins interacting with a homogeneous magnetic field. This field serves to break time-reversal symmetry and results in lattice fluxes that mimic the Aharonov–Bohm phase acquired by electrons. Our proposal is the first blueprint for realizing topological phases of matter in molecular aggregates and suggests a paradigm for engineering novel excitonic materials.

Yuen-Zhou, Joel; Saikin, Semion K.; Yao, Norman Y.; Aspuru-Guzik, Alán

2014-11-01

412

Microwave guiding of electrons on a chip  

E-print Network

Electrons travelling in free space have allowed to explore fundamental physics like the wave nature of matter, the Aharonov-Bohm and the Hanbury Brown-Twiss effect. Complementarily, the precise control over the external degrees of freedom of electrons has proven pivotal for wholly new types of experiments such as high precision measurements of the electron's mass and magnetic moment in Penning traps. Interestingly, the confinement of electrons in the purely electric field of an alternating quadrupole has rarely been considered. Recent advances in the development of planar chip-based ion traps suggest that this technology can be applied to enable entirely new experiments with electron beams guided in versatile potentials. Here we demonstrate the transverse confinement of a low energy electron beam in a linear quadrupole guide based on microstructured planar electrodes and driven at microwave frequencies. A new guided matter-wave system will result, with applications ranging from electron interferometry to novel non-invasive electron microscopy.

Johannes Hoffrogge; Roman Fröhlich; Mark A. Kasevich; Peter Hommelhoff

2010-12-10

413

Coherent states of non-relativistic electron in the magnetic-solenoid field  

NASA Astrophysics Data System (ADS)

In the present work we construct coherent states in the magnetic-solenoid field, which is a superposition of the Aharonov-Bohm field and a collinear uniform magnetic field. In the problem under consideration there are two kinds of coherent states, those which correspond to classical trajectories which embrace the solenoid and those which do not. The constructed coherent states reproduce exactly classical trajectories, maintain their form under the time evolution and form a complete set of functions, which can be useful in semiclassical calculations. In the absence of the solenoid field these states are reduced to the well known in the case of uniform magnetic field Malkin-Man'ko coherent states.

Bagrov, V. G.; Gavrilov, S. P.; Gitman, D. M.; Meira Filho, D. P.

2010-09-01

414

Colloquium: Artificial gauge potentials for neutral atoms  

SciTech Connect

When a neutral atom moves in a properly designed laser field, its center-of-mass motion may mimic the dynamics of a charged particle in a magnetic field, with the emergence of a Lorentz-like force. In this Colloquium the physical principles at the basis of this artificial (synthetic) magnetism are presented. The corresponding Aharonov-Bohm phase is related to the Berry's phase that emerges when the atom adiabatically follows one of the dressed states of the atom-laser interaction. Some manifestations of artificial magnetism for a cold quantum gas, in particular, in terms of vortex nucleation are discussed. The analysis is then generalized to the simulation of non-Abelian gauge potentials and some striking consequences are presented, such as the emergence of an effective spin-orbit coupling. Both the cases of bulk gases and discrete systems, where atoms are trapped in an optical lattice, are addressed.

Dalibard, Jean; Gerbier, Fabrice; Juzeliunas, Gediminas; Oehberg, Patrik [Laboratoire Kastler Brossel, CNRS, UPMC, Ecole normale superieure, 24 rue Lhomond, 75005, Paris (France); Institute of Theoretical Physics and Astronomy, Vilnius University, A. Gostauto 12, Vilnius 01108 (Lithuania); SUPA, Department of Physics, Heriot-Watt University, Edinburgh, EH14 4AS (United Kingdom)

2011-10-01

415

Topologically protected excitons in porphyrin thin films  

E-print Network

The control of exciton transport in organic materials is of fundamental importance for the development of efficient light-harvesting systems. This transport is easily deteriorated by traps in the disordered energy landscape. Here, we propose and analyze a system that supports topological Frenkel exciton edge states. Backscattering of these chiral Frenkel excitons is prohibited by symmetry, ensuring that the transport properties of such a system are robust against disorder. To implement our idea, we propose a two-dimensional periodic array of tilted porphyrins interacting with a homogenous magnetic field. This field serves to break time-reversal symmetry and results in lattice fluxes that that mimic the Aharonov-Bohm phase acquired by electrons. Our proposal is the first blueprint for realizing topological phases of matter in molecular aggregates and suggests a paradigm for engineering novel excitonic materials.

Joel Yuen-Zhou; Semion S. Saikin; Norman Y. Yao; Alán Aspuru-Guzik

2014-06-05

416

A non-qubit quantum adder as one-dimensional cellular automaton  

NASA Astrophysics Data System (ADS)

A complete quantum addition machine is presented and compared with methods employing unitary transformations first. A quantum half-adder circuit shown earlier can be implemented into each cell of a 1D cellular automaton. An electric Aharonov-Bohm effect version of the quantum circuit is used to illustrate this implementation. Whatever a quantum Turing machine can achieve is realized in the cellular automata architecture we propose here. The coherence requirement is limited to one cell area. The magnetic flux needed is 0.1?0, corresponding to 0.414 mT for a ring area of 1 square micron or an electric potential of 0.414 mV at 1 ps with an energy dissipation of 0.041 eV per iteration.

Wu, C. H.; Cain, C. A.

2014-05-01

417

Cylindric quantum wires in a threading magnetic field: A proposal of characterization based on zero bias electron transport  

NASA Astrophysics Data System (ADS)

We study the quantum transport properties of cylindrical shaped wires, with submicrometric diameters and large aspect ratio. The zero bias conductance as a function of temperature, magnetic field and disorder is calculated for different kinds of nano cylinders, from semiconductor quantum wires to carbon nanotubes. A comparison between our findings and the experimental results allows the understanding of the charge carriers' localization, in the external surface or in the core of the wires, by highlighting the basic mechanism of charge transport. We discuss how we can infer that in InAs quantum wires the carriers move in the core. We examine the Aharonov-Bohm oscillations and the quenching that should be observed in the measured magneto conductivity of InAs nano cylinders and carbon nanotubes emphasizing the role of the angle between field and tube.

Onorato, P.

2012-12-01

418

Tunable refraction in a two-dimensional quantum-state metamaterial  

NASA Astrophysics Data System (ADS)

In this paper we consider a two-dimensional quantum-state metamaterial comprising an array of qubits (two-level quantum objects). Here we propose that it should be possible to manipulate the propagation of quantum information. We show that a quantum metamaterial such as the one considered here exhibits several different modes of operation, which we have termed Aharonov-Bohm, intermediate, and quantum-Zeno. We also see interesting behavior which could be thought of as either quantum birefringence (where the material acts like a beam splitter) as well as the emergence of quantum correlations in the circuit's measurement statistics. Quantum-state metamaterials as proposed here may be fabricated from a variety of technologies from superconducting qubits to quantum dots and would be readily testable in existing state-of-the-art laboratories.

Everitt, M. J.; Samson, J. H.; Savel'ev, S. E.; Wilson, R.; Zagoskin, A. M.; Spiller, T. P.

2014-08-01

419

Asymmetric coherent transmission for single particle diode and gyroscope  

E-print Network

We study the single particle scattering process in a coherent multi-site system consisting of a tight-binding ring threaded by an Aharonov-Bohm flux and several attaching leads. The asymmetric behavior of scattering matrix is discovered analytically in the framework of both Bethe Ansatz and Green's function formalism. It is found that, under certain conditions, a three-site electronic system can behave analogous to a perfect semiconductor diode where current flows only in one direction. The general result is also valid for a neutral particle system since the effective magnetic flux may be implemented by a globe rotation. This observation means that the three-site system can serve as an orientation measuring gyroscope due to the approximate linear dependence of the current difference of two output leads on the rotational angular velocity.

S. Yang; Z. Song; C. P. Sun

2009-12-02

420

Geometric phase in Bohmian mechanics  

SciTech Connect

Using the quantum kinematic approach of Mukunda and Simon, we propose a geometric phase in Bohmian mechanics. A reparametrization and gauge invariant geometric phase is derived along an arbitrary path in configuration space. The single valuedness of the wave function implies that the geometric phase along a path must be equal to an integer multiple of 2{pi}. The nonzero geometric phase indicates that we go through the branch cut of the action function from one Riemann sheet to another when we locally travel along the path. For stationary states, quantum vortices exhibiting the quantized circulation integral can be regarded as a manifestation of the geometric phase. The bound-state Aharonov-Bohm effect demonstrates that the geometric phase along a closed path contains not only the circulation integral term but also an additional term associated with the magnetic flux. In addition, it is shown that the geometric phase proposed previously from the ensemble theory is not gauge invariant.

Chou, Chia-Chun, E-mail: chiachun@mail.utexas.ed [Institute for Theoretical Chemistry and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712 (United States); Wyatt, Robert E., E-mail: wyattre@mail.utexas.ed [Institute for Theoretical Chemistry and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712 (United States)

2010-10-15

421

Topologically protected excitons in porphyrin thin films.  

PubMed

The control of exciton transport in organic materials is of fundamental importance for the development of efficient light-harvesting systems. This transport is easily deteriorated by traps in the disordered energy landscape. Here, we propose and analyse a system that supports topological Frenkel exciton edge states. Backscattering of these chiral Frenkel excitons is prohibited by symmetry, ensuring that the transport properties of such a system are robust against disorder. To implement our idea, we propose a two-dimensional periodic array of tilted porphyrins interacting with a homogeneous magnetic field. This field serves to break time-reversal symmetry and results in lattice fluxes that mimic the Aharonov-Bohm phase acquired by electrons. Our proposal is the first blueprint for realizing topological phases of matter in molecular aggregates and suggests a paradigm for engineering novel excitonic materials. PMID:25242533

Yuen-Zhou, Joel; Saikin, Semion K; Yao, Norman Y; Aspuru-Guzik, Alán

2014-11-01

422

Loop Quantization versus Fock Quantization of p-Form Electromagnetism on Static Spacetimes  

E-print Network

As a warmup for studying dynamics and gravitons in loop quantum gravity, Varadajan showed that Wilson loops give operators on the Fock space for electromagnetism in Minkowski spacetime - but only after regularizing the loops by smearing them with a Gaussian. Unregularized Wilson loops are too singular to give densely defined operators. Here we present a rigorous treatment of unsmeared Wilson loops for vacuum electromagnetism on an arbitrary globally hyperbolic static spacetime. Our Wilson loops are not operators, but "quasioperators": sesquilinear forms on the dense subspace of Fock space spanned by coherent states corresponding to smooth classical solutions. To obtain this result we begin by carefully treating electromagnetism on globally hyperbolic static spacetimes, addressing various issues that are usually ignored, such as the definition of Aharonov-Bohm modes when space is noncompact. We then use a new construction of Fock space based on coherent states to define Wilson loop quasioperators. Our results also cover "Wilson surfaces" in p-form electromagnetism.

Miguel Carrión-Álvarez

2004-12-10

423

Kinesiology Undergraduate Student Learning Outcomes (EMS)  

E-print Network

1 Kinesiology Undergraduate Student Learning Outcomes (EMS) Kinesiology Undergraduate Student Learning Outcomes (PE) Kinesiology Graduate Program 1. Students will demonstrate knowledge of and skill sociocultural, historical, and philosophical perspectives on kinesiology. 4. Students will understand how motor

424

Structural Composites with Tuned EM Chirality.  

National Technical Information Service (NTIS)

We have developed and implemented methods to predict the overall EM properties tensors including the coupling tensors based on the geometry and microstructure of an array of scattering elements, and fabricated and measured both the HM and mechanical prope...

S. Nemat-Nasser

2009-01-01

425

Sincronizao em Sistemas Distribudos problemas clssicos  

E-print Network

problema de coordenação distribuída #12;ordenação de mensagens · implementação ­ uso de uma fila de holdback em camada de comunicação chegada de mensagens processamento (aplicação) fila entrega fila holdback destinatário responde com uma proposta de número de ordem ­ e deixa (msg, id_único, num_ordem_proposto) em fila

Rodriguez, Noemi

426

Condições físicas em galáxias HII  

NASA Astrophysics Data System (ADS)

Galáxias HII são galáxias anãs de baixa luminosidade que apresentam alta taxa de formação estelar. Seus espectros são dominados por intensas linhas de emissão devido à fotoionização pela presença de um grande número de estrelas do tipo O e B. Nós apresentamos um catálogo espectrofotométrico de 111 galáxias HII observadas no telescópio 1.52m do ESO com o espectrógrafo Boller & Chivens. Determinamos propriedades estatísticas da amostra e derivamos condições físicas (temperatura eletrônica, densidade eletrônica) e abundâncias químicas. Para algumas galáxias, fomos também capazes de resolver espacialmente regiões de formação estelar individuais e determinar propriedades espectroscópicas para estas regiões separadamente, o que nos permitiu avaliar as flutuações das condições físico-químicas dentro das galáxias HII. Em particular, vimos que apesar das galáxias HII apresentarem formação estelar espalhada ao longo do corpo da galáxia, são objetos quimicamente homogêneos. A fim de estudar a evolução temporal dos objetos durante o tempo de vida das estrelas ionizantes construimos também alguns diagramas relacionando razões de linhas de emissão com a largura equivalente de Hb (EW(Hb)). Para interpretar tais diagramas utilizamos modelos de fotoionização para populações estelares integradas. Concluímos que as galáxias HII não correspondem a simples idéia de um burst instantâneo envolvido por um gás opaco aos fótons ionizantes e com densidade constante. As relações observadas entre razões de linhas e EW(Hb) podem ser melhor compreendidas se as galáxias HII apresentarem populações estelares mais velhas, que contribuem para o contínuo óptico observado.

Kehrig, C.; Telles, E.; Cuisinier, F.

2003-08-01

427

FAST TRACK COMMUNICATION: ZnSe/ZnTe(shell/shell) radial quantum-wire heterostructures: the excitonic properties  

NASA Astrophysics Data System (ADS)

The ground-state characteristics of spatially indirect excitons trapped in radially heteronanostructured type-II band alignment ZnSe/ZnTe nanotubes as functions of the magnetic field for nanotubes with a radial size both smaller and larger than the effective Bohr radius are theoretically investigated. In the former case, dominated by the net kinetic energy of the electron and hole, the magnetic field modifies the exciton spectrum through the well-known Zeeman splitting, intra-orbital-state Aharonov-Bohm oscillations and inter-orbital-state crossovers occurring in very strong magnetic field strengths. However, in the latter case, dominated by the electron-hole Coulomb attraction, the magnetic field adjusts the exciton lines only by means of the Zeeman splitting and inter-orbital-state transitions happening in typical magnetic fields. As a result, the angular momentum transitions occurr at lower magnetic fields when the radial size of the nanotube is increased. Most importantly, another consequence is the substantially unusual exciton oscillator strength in such heteronanostructures. It is shown that when the exciton is optically active, due to the full cylindrical symmetry of the problem, the exciton oscillator strength shows undamped oscillations. This effect is associated with the periodic redistribution of the exciton density as the magnetic field is varied. Also, the magnitude of the magnetically induced excitonic persistent current is decreased with increasing radial size of the nanotube. This study may provide a platform to investigate new photonic quantum interference as well as polarization-sensitive photodetector and photovoltaic devices based on the Aharonov-Bohm effect.

Bagheri, Mehran

2010-07-01

428

Phase diagram of the Bose-Hubbard model with T{sub 3} symmetry  

SciTech Connect

We study the quantum phase transition between the insulating and the globally coherent superfluid phases in the Bose-Hubbard model with T{sub 3} structure, the 'dice lattice'. Even in the absence of any frustration the superfluid phase is characterized by modulation of the order parameter on the different sublattices of the T{sub 3} structure. The zero-temperature critical point as a function of magnetic field shows the characteristic 'butterfly' form. At full frustration the superfluid region is strongly suppressed. In addition, due to the existence of the Aharonov-Bohm cages at f=1/2, we find some evidence for the existence of an intermediate insulating phase characterized by a zero superfluid stiffness but finite compressibility. In this intermediate phase bosons are localized due to the external frustration and the topology of the T{sub 3} lattice. We name this new phase the Aharonov-Bohm insulator. In the presence of charge frustration the phase diagram acquires the typical lobe structure. The form and hierarchy of the Mott insulating states with fractional fillings are dictated by the particular topology of the T{sub 3} lattice. The results presented were obtained by a variety of analytical methods: mean-field and variational techniques to approach the phase boundary from the superconducting side and a strongly coupled expansion appropriate for the Mott insulating region. In addition we performed quantum Monte Carlo simulations of the corresponding (2+1)-dimensional XY model to corroborate the analytical calculations with a more accurate quantitative analysis. We finally discuss experimental realization of the T{sub 3} lattice both with optical lattices and with Josephson junction arrays.

Rizzi, Matteo; Fazio, Rosario [NEST CNR-INFM and Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa (Italy); Cataudella, Vittorio [COHERENTIA CNR-INFM and Dipartimento di Fisica, Universita Federico II, 80126 Naples (Italy)

2006-04-01

429

Optical Spectroscopy of Single-Walled Carbon Nanotubes Under Extreme Conditions  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNTs) are one of the leading candidate materials to realize novel nanoscale photonic devices. In order to assess their performance characteristics as optoelectronic materials, it is crucial to examine their optical properties in highly non-equilibrium situations such as high magnetic fields, low temperatures, and under high photoexcitation. Therefore, we present our latest result on the magnetic susceptibility anisotropy of metallic carbon nanotubes due to the Aharonov-Bohm effect. Here, we performed magnetic linear dichroism on a metallic-enriched HiPco SWNT sample utilizing a 35 T Hybrid Magnet to measure absorption with light polarization both perpendicular and parallel to the magnetic field. By relating these values with the nematic order parameter for alignment, we found that the metallic carbon nanotubes do not follow a strict diameter dependence across the 7 chiralities present in our sample. In addition to the studying the absorption properties exhibited at high magnetic field, we performed temperature-dependent (300 K to 11 K) photoluminescence (PL) on HiPco SWNTs embedded in an iota-carrageenan matrix utilizing intense fs pulses from a wavelength-tunable optical parametric amplifier. We found that for each temperature the PL intensity saturates as a function of pump fluence and the saturation intensity increases from 300 K to a moderate temperature around 100-150 K. Within the framework of diffusion-limited exciton-exciton annihilation (EEA), we successfully estimated the density of 1D excitons in SWNTs as a function of temperature and chirality. These results coupled with our results of magnetic brightening, or an increase in PL intensity as a function of magnetic flux through each SWNT due to the Aharonov-Bohm effect, yield great promise that in the presence of a high magnetic field the density of excitons can be further increased.

Searles, Thomas A., Jr.

430

Quantum coherent transport through a quadruple quantum-dot structure with one continuous channel and two concrete channels  

NASA Astrophysics Data System (ADS)

We investigate the coherent transport through a mesoscopic ring composed of four circularly coupled quantum dots (QDs) by means of nonequilibrium Green’s functions. Two QDs of the mesoscopic ring with infinite intradot Coulomb interaction serve as two Kondo impurities, which are coupled together by three channels: the direct interdot coupling channel and the other two QD channels. This quadruple QD (QQD) system, including two subrings, is versatile and intriguing due to its advantages in simultaneous studying of the Kondo, Fano, and Aharonov-Bohm effects. We analytically and numerically studied the quantum transport properties of the symmetrical and asymmetrical QQD in both the absence and presence of a magnetic field. First we focus on the linear transport properties without the magnetic field. In the symmetrical QQD, the linear conductance shows a simple pattern with a single peak or double peak when the interdot coupling between two Kondo impurities is weak. However, by increasing this interdot coupling, the conductance evolves into a pattern characteristic of one deep trough. Sharply different from the symmetrical QQD, the conductance in an asymmetrical QQD shows a double peak or triple peak pattern in the case of the weak coupling between two Kondo impurities, and it shows a double trough pattern for the strong coupling. Moreover, we consider the influences on the transport induced by the magnetic field. It is demonstrated that the conductance shows complex oscillations associated with the Kondo, Fano, and Aharonov-Bohm effects, clearly depicting the competitions among them. The oscillation period as a function of magnetic flux is determined by the magnetic-flux ratio threaded into two subrings. The phase rigidity is clearly observed when one intermediate QD energy level passes through the lead Fermi level. Lastly we extend our results into the system with many QD channels used to connect the two Kondo impurities, which gives a complete picture about the transport properties in such a kind of double impurity QD devices.

Jiang, Zhao-Tan; Han, Qing-Zhen

2008-07-01

431

DIVISÃO DE TRABALHO E RELAÇAO DE GÊNERO EM COMUNIDADES AMAZÔNICAS: UMA REALIDADE EM TRANSFORMAÇÃO  

Microsoft Academic Search

As relações de gênero constituem o conjunto das relações sociais e econômicas no universo do trabalho, da cultura e da política. Está organizada a partir dos papéis masculinos e femininos dentro de estruturas que permanecem constantes em algumas sociedades ou de forma presente no inconsciente social que às vezes é refletido em ações do cotidiano colocando cada agente social dentro

Albejamere Pereira de Castro

432

SOFIS FTS EM test results  

NASA Astrophysics Data System (ADS)

The Solar Occultation FTS for Inclined-orbit Satellite (SOFIS) is a solar occultation Fourier transform spectrometer developed by the Ministry of the Environment (MOE) in Japan for the Global Change Observation Mission-A1 (GCOM-A1) satellite. GCOM-A1 will be placed in a 650 km non-sun-synchronous orbit, with an inclination angle of 69 degrees. ABB-Bomem is a sub-contractor of NTSpace (NEC-Toshiba Space) for the design and manufacturing of the FTS Engineering Model of SOFIS. SOFIS measures the vertical profile of the atmospheric constituents with 0.2 cm-1 spectral resolution for the spectral range covering 3-13 ?m. The atmospheric vertical resolution of SOFIS is 1 km. The target of SOFIS measurements is a global distribution of O3, HNO3, NO2, N2O, CH4, H2O, CO2, CFC-11, CFC-12, ClONO2, aerosol extinction, atmospheric pressure and temperature. NTSpace in Japan is the prime contractor of SOFIS. The spectrometer is an adapted version of the classical Michelson interferometer using an optimized optical layout and moving retro-reflectors. A solid-state laser diode operating at 1550 nm is used as metrology source of the interferometer. Its highly folded optical design results in a high performance instrument with a compact size. SOFIS FTS implements high performance control techniques to achieve outstanding speed stability of the moving mechanism. This paper describes the test activities of the SOFIS-FTS Engineering Model (EM) and preliminary results. The performances of the FTS are presented in terms of key parameters like signal-to-noise ratio, modulation efficiency and stability. Spectra acquired are shown and test methodology and analyses are presented. Lessons learned during assembly, integration and testing are described as well as improvements planned to be implemented in the Flight Model.

Soucy, Marc-Andre A.; Levesque, Luc E.; Tanii, Jun; Kawashima, Takahiro; Nakajima, Hideaki

2003-04-01

433

Tour of the Electromagnetic Spectrum (EMS) Videos  

NSDL National Science Digital Library

These videos introduce middle- and high school-age learners to the electromagnetic spectrum. The product consists of 8 animations including an introduction to electromagnetic waves and one animation for each wavelength of the EM spectrum (Radio, Microwave, Infrared, Visible, Ultraviolet, X-Rays and Gamma Rays). Each wavelength of the EM spectrum offers a construct to illustrate and teach about NASA sensors, missions, and science. Emphasis is placed on relevant science, such as lunar exploration, and hot science topics, such as climate change. The examples and narrative for each wavelength animation build on the learnersâ prior knowledge then introduces examples from NASA missions. These examples explore the use of spectral analysis and visualizations that help scientists make discoveries about the world around us using EM waves.

Benesch, Troy

2009-01-01

434

Risk Communication Within the EM Program  

SciTech Connect

The U.S. Department of Energy Environmental Management program (EM) conducts the most extensive environmental remediation effort in the world. The annual EM budgets have exceeded $6,000,000,000 for approximately ten years and EM has assumed responsibility for the cleanup of the largest DOE reservations (i.e., at Hanford, Washington, Aiken, South Carolina, and Idaho Falls, Idaho) as well as the facilities at Rocky Flats, Colorado and in Ohio. Each of these sites has areas of extensive radioactive and chemical contamination, numerous surplus facilities that require decontamination and removal, while some have special nuclear material that requires secure storage. The EM program has been criticized for being ineffective (1) and has been repeatedly reorganized to address perceived shortcomings. The most recent reorganization was announced in 2001 to become effective at the beginning of the 2003 Federal Fiscal Year (i.e., October 2002). It was preceded by a ''top to bottom'' review (TTBR) of the program (2) that identified several deficiencies that were to be corrected as a result of the reorganization. One prominent outcome of the TTBR was the identification of ''risk reduction'' as an organizing principle to prioritize the activities of the new EM program. The new program also sought to accelerate progress by identifying a set of critical activities at each site that could be accelerated and result in more rapid site closure, with attendant risk, cost, and schedule benefits. This paper investigates how the new emphasis on risk reduction in the EM program has been communicated to EM stakeholders and regulators. It focuses on the Rocky Flats Environmental Technology Site (RFETS) as a case study and finds that there is little evidence for a new emphasis on risk reduction in EM communications with RFETS stakeholders. Discussions between DOE and RFETS stakeholders often refer to ''risk,'' but the word serves as a placeholder for other concepts. Thus ''risk'' communication at RFETS is lively and involves important issues, but often does not inform participants about true ''risk reduction.''

Edelson, M.

2003-02-26

435

7 CFR 1945.35 - Special EM loan training.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 false Special EM loan training. 1945.35 Section 1945.35 Agriculture Regulations of the Department...CONTINUED) EMERGENCY Disaster Assistance-General § 1945.35 Special EM loan training. (a)...

2012-01-01

436

7 CFR 1945.35 - Special EM loan training.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 true Special EM loan training. 1945.35 Section 1945.35 Agriculture Regulations of the Department...CONTINUED) EMERGENCY Disaster Assistance-General § 1945.35 Special EM loan training. (a)...

2010-01-01

437

7 CFR 1945.35 - Special EM loan training.  

Code of Federal Regulations, 2011 CFR

...2009-01-01 true Special EM loan training. 1945.35 Section 1945.35 Agriculture Regulations of the Department...CONTINUED) EMERGENCY Disaster Assistance-General § 1945.35 Special EM loan training. (a)...

2011-01-01

438

EM-ONE : an architecture for reflective commonsense thinking  

E-print Network

This thesis describes EM-ONE, an architecture for commonsense thinking capable of reflective reasoning about situations involving physical, social, and mental dimensions. EM-ONE uses as its knowledge base a library of ...

Singh, Pushpinder, 1972-2006.

2005-01-01

439

UNIVERSIDADE DE BRASLIA PROGRAMA DE PS-GRADUAO EM ECONOMIA  

E-print Network

1 UNIVERSIDADE DE BRASÍLIA PROGRAMA DE P�S-GRADUA��O EM ECONOMIA EDITAL No. 04/2011 SELE��O DE CANDIDATOS �S VAGAS DO PROGRAMA DE P�S-GRADUA��O EM ECONOMIA PARA O CURSO DE MESTRADO PROFISSIONAL EM ECONOMIA ­ AREA DE CONCENTRA��O EM GEST�O ECON�MICA DE FINAN�AS P�BLICAS PARA O SEGUNDO PERÍODO LETIVO DE

Lucero, Jorge Carlos

440

UNIVERSIDADE DE BRASLIA PROGRAMA DE PS-GRADUAO EM ECONOMIA  

E-print Network

1 UNIVERSIDADE DE BRASÍLIA PROGRAMA DE P�S-GRADUA��O EM ECONOMIA EDITAL No. 4/2013 SELE��O DE CANDIDATOS �S VAGAS DO PROGRAMA DE P�S-GRADUA��O EM ECONOMIA PARA O CURSO DE MESTRADO PROFISSIONAL EM ECONOMIA ­ AREA DE CONCENTRA��O EM GEST�O ECON�MICA DE FINAN�AS P�BLICAS PARA O SEGUNDO PERÍODO LETIVO DE

Maier, Rudolf Richard

441

UNIVERSIDADE DE BRASLIA PROGRAMA DE PS-GRADUAO EM ECONOMIA  

E-print Network

1 UNIVERSIDADE DE BRASÍLIA PROGRAMA DE P�S-GRADUA��O EM ECONOMIA EDITAL No. 5/2013 SELE��O DE CANDIDATOS �S VAGAS DO PROGRAMA DE P�S-GRADUA��O EM ECONOMIA PARA O CURSO DE MESTRADO PROFISSIONAL EM ECONOMIA ­ AREA DE CONCENTRA��O EM GEST�O ECON�MICA DE FINAN�AS P�BLICAS PARA O SEGUNDO PERÍODO LETIVO DE

Maier, Rudolf Richard

442

Marvin, robô construtor para competição em robótica móvel  

Microsoft Academic Search

renatohsp@gmail .com Resumo: Este artigo é sobre a construção do robô autônomo Marvin o Construtor, que foi construído para participar da IV Competição IEEE Brasileira de Robô. A tarefa consiste em empilhar blocos em uma área predeterminada em um menor tempo possível, ganha a torre mais alta. O robô, construído por alunos do Instituto Tecnológico de Aeronáutica (ITA), foi construído

André Martin Narciso; Carlos Augusto; Bentes da Silva; Jackson Paul Matsuura

443

On Convergence Properties of the EM Algorithm for Gaussian Mixtures  

Microsoft Academic Search

We build up the mathematical connection between the Expectation-Maximization (EM) algorithm and gradient-based approaches for maximum likelihood learning of finite gaussian mixtures. We show that the EM step in parameter space is obtained from the gradient via a projection matrix P, and we provide an explicit expression for the matrix. We then analyze the convergence of EM in terms of

Lei Xu; Michael I. Jordan

1996-01-01

444

GEOBULLETIN NOvEmBEr 15Th  

E-print Network

to hydrothermal convection of groundwater connected to surface water Thermal springs are ubiquitous features whose;GEOBULLETIN NOvEmBEr 15Th 2013 - 2 - hydrothermal convection cells circulating groundwater within the near hydrothermal circulation of groundwater. For example, these requirements are met in many areas within

Carlson, Anders

445

de Ps-Graduao em Enfermagem  

E-print Network

CAPES/PNPD A Profa. Dra Marta Lenise do Prado, docente do Programa de Pós-graduação em Enfermagem da (via e-mail), para agendar uma entrevista para arguição do currículo, considerando o perfil adequado ao

Floeter, Sergio Ricardo

446

EMS response to an airliner crash.  

PubMed

This report of an aircraft crash at a major airport in Kingston, Jamaica examines the response of the local Emergency Medical Services (EMS). Factors that impacted the response are discussed, and the need for more disaster simulation exercises is highlighted. The objective of this case report was to document the response of EMS personnel to the crash of American Airlines Flight 331, and to utilize the information to examine and improve the present protocol. While multiple errors can occur during a mass-casualty event, these can be reduced by frequent simulation exercises during which various personnel practice and learn designated roles. Efficient triage, proper communication, and knowledge of the roles are important in ensuring the best possible outcome. While the triage system and response of the EMS personnel were effective for this magnitude of catastrophe, more work is needed in order to meet predetermined standards. Ways in which this can be overcome include: (1) hosting more disaster simulation exercises; (2) encouraging more involvement with first responders; and (3) strengthening the links in the local EMS system. Vigorous public education must be instituted and maintained. PMID:22853919

Dasgupta, Shuvra; French, Simone; Williams-Johnson, Jean; Hutson, Rhonda; Hart, Nicole; Wong, Mark; Williams, Eric; Espinosa, Kurdell; Maycock, Celeste; Edwards, Romayne; McCartney, Trevor; Cawich, Shamir; Crandon, Ivor

2012-06-01

447

CNMP, CSP, EMS and Writing It Down  

E-print Network

by farmers, leading to... · Increasing importance of "writing it down" #12;Examples.. · NMP, CNMP · PMPOp & plan for more · III - meet all natural resource concerns #12;NMP & CNMP · NMP in WI rules; CNMP and erosion #12;EMS is HQ · CSP, NMP, PMP, CNMP alphabet soup · Are components of an Environmental Management

Balser, Teri C.

448

CURSO DE PS-GRADUAO EM METEOROLOGIA  

E-print Network

CURSO DE P�S-GRADUA��O EM METEOROLOGIA Coordenadora Acadêmica Maria Paulete Pereira Martins Membros Bueno Pereira, Ph.D., W.M.Rice University, 1980 Gilberto Fernando Fisch, Doutor, INPE, 1995 Iracema, INPE, 2002 Maria Paulete Pereira Martins, Doutora, INPE, 1996 Marley Cavalcante de Lima Moscati

449

CURSO DE PS-GRADUAO EM METEOROLOGIA  

E-print Network

CURSO DE P�S-GRADUA��O EM METEOROLOGIA Coordenadora Acadêmica Maria Paulete Pereira Martins Bueno Pereira, Ph.D., W.M.Rice University, 1980 Gilberto Fernando Fisch, Doutor, INPE, 1995 Iracema, INPE, 2002 Maria Paulete Pereira Martins, Doutora, INPE, 1996 Marley Cavalcante de Lima Moscati

450

CURSO DE PS-GRADUAO EM METEOROLOGIA  

E-print Network

CURSO DE P�S-GRADUA��O EM METEOROLOGIA Coordenadora Acadêmica Maria Paulete Pereira Martins-USP, 2002 �nio Bueno Pereira, Ph.D., W.M.Rice University, 1980 Gilberto Fernando Fisch, Doutor, INPE, 1995, INPE, 2002 Maria Paulete Pereira Martins, Doutora, INPE, 1996 Marley Cavalcante de Lima Moscati

451

GEOBULLETIN NOvEmBEr 8Th  

E-print Network

GEOBULLETIN NOvEmBEr 8Th 2013 - 1 - GeoBulletin is distributed weekly, by E-mail. Contributions are requested! If you have a news item, a request, an announcement etc. email it to geodept@geology.wisc.edu or leave it at the office, Room 225 by Noon on Wednesday. WEEKS LECTURE - FALL 2013 Nov. 8 Graham Kent

Carlson, Anders

452

Regional EM studies in the 80's  

NASA Astrophysics Data System (ADS)

The review describes in broad terms the development of regional EM studies during the last five-six years. Large simultaneous magnetometer arrays, broadband and dense profiling with five component instruments, the use of remote reference techniques and in-field data processing have increased both the number and the quality of EM surveys. The increase has been strong all over the world. An extensive list of references, divided geographically, is presented. Selected examples of regional resisitivity-versus-depth curves are shown for Africa, the Baikal region, the Baltic Shield, the Canadian Shield, the Carpathian regions, the Central Andes, Iceland, India, the Juan de Fuca Plate, the Münsterland Basin, the Rio Grande rift, the Scottish Caledonides, the Tasman Sea, and for the United States in general. Because of the influence of tectonic settings and the metamorphic grade of rocks, only qualitative aspects of the results are relevant. ‘Classical’ array studies, especially in Australia, in the Carpathian regions, in India, in North Germany and in Scotland have been reinterpreted and completed with more accurate 2D modelling and dense MT profiling. In the USA and Canada also new regions have been surveyed extensively. New regional EM work has been conducted extensively on the Baltic Shield and in Central and North Africa, Siberia, China, in the areas around the Caspian and Black Seas and in South America. The newest studies are supported by or compared with other geophysical data, which also are used in extrapolating for missing EM data density. There are several successful large-scale projects in operation: the European Geotraverse (EGT), the KAPG International Geotraverses and the EMSLAB project (with its first preliminary results). Regional EM studies have been increasingly applied to geothermal, hydrocarbon and mineral prospecting as well as local structural studies, e.g. studies of sites for nuclear waste disposal.

Hjelt, S. E.

1987-09-01

453

Modelling and design for PM/EM magnetic bearings  

NASA Technical Reports Server (NTRS)

A mathematical model of a permanent magnet/electromagnet (PM/EM) radially active bearing is presented. The bearing is represented by both a reluctance model and a stiffness model. The reluctance model analyzes the magnetic circuit of the PM/EM bearings. By combining the two models, the performance of the bearing can be predicted given geometric dimensions, permanent magnet strength, and the parameters of the EM coils. The overall bearing design including the PM and EM design is subject to the performance requirement and physical constraints. A study of these requirements and constraints is discussed. The PM design is based on the required magnetic flux for proper geometric dimensions and magnet strength. The EM design is based on the stability and force slew rate consideration, and dictates the number of turns for the EM coils and the voltage and current of the power amplifier. An overall PM/EM bearing design methodology is proposed and a case study is also demonstrated.

Pang, D.; Kirk, J. A.; Anand, D. K.; Johnson, R. G.; Zmood, R. B.

1992-01-01

454

The association between EMS workplace safety culture and safety outcomes  

PubMed Central

Objective Prior studies have highlighted wide variation in EMS workplace safety culture across agencies. We sought to determine the association between EMS workplace safety culture scores and patient or provider safety outcomes. Methods We administered a cross-sectional survey to EMS workers affiliated with a convenience sample of agencies. We recruited these agencies from a national EMS management organization. We used the EMS Safety Attitudes Questionnaire (EMS-SAQ) to measure workplace safety culture and the EMS Safety Inventory (EMS-SI), a tool developed to capture self-reported safety outcomes from EMS workers. The EMS-SAQ provides reliable and valid measures of six domains: safety climate, teamwork climate, perceptions of management, perceptions of working conditions, stress recognition, and job satisfaction. A panel of medical directors, paramedics, and occupational epidemiologists developed the EMS-SI to measure self-reported injury, medical errors and adverse events, and safety-compromising behaviors. We used hierarchical linear models to evaluate the association between EMS-SAQ scores and EMS-SI safety outcome measures. Results Sixteen percent of all respondents reported experiencing an injury in the past 3 months, four of every 10 respondents reported an error or adverse event (AE), and 90% reported safety-compromising behaviors. Respondents reporting injury scored lower on 5 of the 6 domains of safety culture. Respondents reporting an error or AE scored lower for 4 of the 6 domains, while respondents reporting safety-compromising behavior had lower safety culture scores for 5 of 6 domains. Conclusions Individual EMS worker perceptions of workplace safety culture are associated with composite measures of patient and provider safety outcomes. This study is preliminary evidence of the association between safety culture and patient or provider safety outcomes. PMID:21950463

Weaver, Matthew D.; Wang, Henry E.; Fairbanks, Rollin J.; Patterson, Daniel

2012-01-01

455

Crosshole EM in steel-cased boreholes  

SciTech Connect

The application of crosshole EM methods through steel well-casing was investigated in theoretical, laboratory and field studies. A numerical code was developed that calculates the attenuation and phase delay of an EM dipole signal propagated through a steel well casing lodged in a homogeneous medium. The code was validated with a scale model and used for sensitivity studies of casing and formation properties. Finally, field measurements were made in an oil field undergoing waterflooding. Our most important findings are that (1) crosshole surveys are feasible using a well pair with one metallic and one non-metallic casing. (2) The casing effect seems be localized within the pipe section that includes the sensor. (3) The effects of the casing can be corrected using simple means and (4) crosshole field data that are sensitive to both formation and casing were acquired in a working environment.

Wilt, M.; Lee, K.H.; Becker, A.; Spies, B.; Wang, B.

1996-07-01

456

Helicopter EMS: Research Endpoints and Potential Benefits  

PubMed Central

Patients, EMS systems, and healthcare regions benefit from Helicopter EMS (HEMS) utilization. This article discusses these benefits in terms of specific endpoints utilized in research projects. The endpoint of interest, be it primary, secondary, or surrogate, is important to understand in the deployment of HEMS resources or in planning further HEMS outcomes research. The most important outcomes are those which show potential benefits to the patients, such as functional survival, pain relief, and earlier ALS care. Case reports are also important “outcomes” publications. The benefits of HEMS in the rural setting is the ability to provide timely access to Level I or Level II trauma centers and in nontrauma, interfacility transport of cardiac, stroke, and even sepsis patients. Many HEMS crews have pharmacologic and procedural capabilities that bring a different level of care to a trauma scene or small referring hospital, especially in the rural setting. Regional healthcare and EMS system's benefit from HEMS by their capability to extend the advanced level of care throughout a region, provide a “backup” for areas with limited ALS coverage, minimize transport times, make available direct transport to specialized centers, and offer flexibility of transport in overloaded hospital systems. PMID:22203905

Thomas, Stephen H.; Arthur, Annette O.

2012-01-01

457

Sequence analysis of two tandemly linked Em genes from wheat  

Microsoft Academic Search

DNA sequences are presented for two members of the wheat Em gene family. The sequences correspond to the two linked genes at the Xem-1AL locus. Comparisons of these sequences with that of another wheat Em gene and two Em cDNA clones reveals substantial homology within the protein-coding regions, and the presence in the 5'-flanking regions of the genomic sequences of

T. Simon Futers; Sertac Onde; Muge Turet; Andrew C. Cuming

1993-01-01

458

Photon kinetic description of 1D relativistic EM pulse solitons  

Microsoft Academic Search

Photon kinetics provides a novel formalism to describe intense EM fields-plasma interactions, where the EM fields are described as a collection of quasi-particles (photons). Photon kinetics provides a better physical picture of the EM fields dynamics, is computionally less demanding, and allows for an easy description of broadband incoherent light pulses. We have developed a 1D photon kinetic code, where

R. Trines; R. Bingham; W. B. Mori; L. O. Silva

2003-01-01

459

UNIVERSIDADE DE BRASLIA PROGRAMA DE PS-GRADUAO EM ECONOMIA  

E-print Network

UNIVERSIDADE DE BRASÍLIA PROGRAMA DE P�S-GRADUA��O EM ECONOMIA EDITAL No. 03/2012 SELE��O DE CANDIDATOS �S VAGAS DO PROGRAMA DE P�S- GRADUA��O EM ECONOMIA PARA O CURSO DE DOUTORADO ACAD�MICO PARA O PRIMEIRO SEMESTRE LETIVO DE 2013 A Coordenação do Programa de Pós-Graduação em Economia da Universidade de

Maier, Rudolf Richard

460

UNIVERSIDADE DE BRASLIA PROGRAMA DE PS-GRADUAO EM ECONOMIA  

E-print Network

1/4 UNIVERSIDADE DE BRASÍLIA PROGRAMA DE P�S-GRADUA��O EM ECONOMIA EDITAL No. 02/2011 SELE��O DE CANDIDATOS �S VAGAS DO PROGRAMA DE P�S-GRADUA��O EM ECONOMIA PARA O CURSO DE DOUTORADO PARA O PRIMEIRO PERÍODO LETIVO DE 2012 1. PRE�MBULO 1.1. O Coordenador do Programa de Pós-Graduação em Economia, no uso de

Maier, Rudolf Richard

461

UNIVERSIDADE DE BRASLIA PROGRAMA DE PS-GRADUAO EM ECONOMIA  

E-print Network

UNIVERSIDADE DE BRASÍLIA PROGRAMA DE P�S-GRADUA��O EM ECONOMIA EDITAL No. 03/2013 SELE��O DE CANDIDATOS �S VAGAS DO PROGRAMA DE P�S- GRADUA��O EM ECONOMIA PARA O CURSO DE DOUTORADO ACAD�MICO PARA O PRIMEIRO SEMESTRE LETIVO DE 2014 PRE�MBULO O Coordenador do Programa de Pós-Graduação em Economia da

Maier, Rudolf Richard

462

UNIVERSIDADE DE BRASLIA PROGRAMA DE PS-GRADUAO EM ECONOMIA  

E-print Network

UNIVERSIDADE DE BRASÍLIA PROGRAMA DE P�S-GRADUA��O EM ECONOMIA EDITAL No. 04/2011 SELE��O DE CANDIDATOS �S VAGAS DO PROGRAMA DE P�S- GRADUA��O EM ECONOMIA PARA O CURSO DE DOUTORADO ACAD�MICO PARA O PRIMEIRO SEMESTRE LETIVO DE 2012 A Coordenação do Programa de Pós-Graduação em Economia da Universidade de

Lucero, Jorge Carlos

463

UNIVERSIDADE DE BRASLIA PROGRAMA DE PS-GRADUAO EM ECONOMIA  

E-print Network

1/4 UNIVERSIDADE DE BRASÍLIA PROGRAMA DE P�S-GRADUA��O EM ECONOMIA EDITAL No. 02/2010 SELE��O DE CANDIDATOS �S VAGAS DO PROGRAMA DE P�S-GRADUA��O EM ECONOMIA PARA O CURSO DE DOUTORADO PARA O PRIMEIRO PERÍODO LETIVO DE 2011 1. PRE�MBULO 1.1. O Coordenador do Programa de Pós-Graduação em Economia, no uso de

Maier, Rudolf Richard

464

UNIVERSIDADE DE BRASLIA PROGRAMA DE PS-GRADUAO EM ECONOMIA  

E-print Network

1/3 UNIVERSIDADE DE BRASÍLIA PROGRAMA DE P�S-GRADUA��O EM ECONOMIA EDITAL No. 01/2011 SELE��O DE CANDIDATOS �S VAGAS DO PROGRAMA DE P�S-GRADUA��O EM ECONOMIA PARA O CURSO DE MESTRADO ACAD�MICO PARA O PRIMEIRO PERÍODO LETIVO DE 2012 1. PRE�MBULO 1.1. O Coordenador do Programa de Pós-Graduação em Economia

Lucero, Jorge Carlos

465

2. HI PAR (ACQUISITION RADAR) TOWER AND ENLISTED MEN (EM) ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. HI PAR (ACQUISITION RADAR) TOWER AND ENLISTED MEN (EM) BARRACKS WITH RADAR ATTACHED. - Nike Hercules Missile Battery Summit Site, Battery Control Administration & Barracks Building, Anchorage, Anchorage, AK

466

Propriedades termodinâmicas de um gás ideal em superfícies hiperbólicas compactas.  

E-print Network

??Neste trabalho investigamos algumas propriedades termodinâmicas de gases ideais em superfícies compactas de curvatura constante e negativa. Super- fícies com propriedades similares aparecem, por exemplo,… (more)

Diego de Flôor e Silva

2012-01-01

467

BUSCA LOCAL PARA POS-PROCESSAMENTO EM RESULTADOS DE OTIMIZAC~AO MULTI-OBJETIVO EM REDES DE FILAS  

E-print Network

BUSCA LOCAL PARA P´OS-PROCESSAMENTO EM RESULTADOS DE OTIMIZA¸C~AO MULTI-OBJETIVO EM REDES DE FILAS otimiza¸c~ao de redes de filas finitas, a capacidade total do sistema em ´areas de espera deve ser a menor redistribui¸c~ao de ´areas de circula¸c~ao entre as filas, preservando fixa a capacidade total do sistema. Um

Cruz, Frederico

468

HISTÓRIA, LITERATURA E DITADURA: O CASO JOÃO PAZ EM INCIDENTE EM ANTARES  

Microsoft Academic Search

This article refers to a possible critic of the Brazilian military and dictatorial regime in the 1960´s and 1970s, trough the eyes of João Paz, a character in the novel of Erico Veríssimo, Incidente em Antares . The research, from a bibliographic point of view, has been based on recent theories that relate to facts in the History and Literature

Daniela Freitas Torres; Elaine dos Santos

469

10 CFR Appendixes E-M to Part 52 - [Reserved  

10 Energy 2 2014-01-01 2014-01-01 false [Reserved] E Appendixes E-M to Part 52 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) LICENSES, CERTIFICATIONS, AND APPROVALS FOR NUCLEAR POWER PLANTS Appendixes E-M to Part 52...

2014-01-01

470

Under Review Scaling Down EM Using Graph Based  

E-print Network

a probabilistic model formulation characterized by the parameters of the probability distribution. For example, in the above applications [3, 17] a #12;Scaling Down EM Using Graph Based Models 3 Gaussian distributionUnder Review Scaling Down EM Using Graph Based Models Ian Davidson Department of Computer Science

Davidson, Ian

471

BENJAMIN FRANKLIN E A HISTÓRIA DA ELETRICIDADE EM LIVROS DIDÁTICOS  

Microsoft Academic Search

Introdução Nos últimos anos, a história da ciência vem sendo introduzida em materiais didáticos utilizados em sala de aula. Uma das razões para isso é a pressão de órgãos governamentais, tais como a Secretaria de Educação Básica, responsável pela avaliação destes livros dentro do Programa Nacional de Livros Didáticos para o ens ino fundamental e médio. Os editais destes programas

Cibelle Celestino Silva; Ana Carolina Pimentel

472

Stochastic EM-based TFBS motif discovery with MITSU  

PubMed Central

Motivation: The Expectation–Maximization (EM) algorithm has been successfully applied to the problem of transcription factor binding site (TFBS) motif discovery and underlies the most widely used motif discovery algorithms. In the wider field of probabilistic modelling, the stochastic EM (sEM) algorithm has been used to overcome some of the limitations of the EM algorithm; however, the application of sEM to motif discovery has not been fully explored. Results: We present MITSU (Motif discovery by ITerative Sampling and Updating), a novel algorithm for motif discovery, which combines sEM with an improved approximation to the likelihood function, which is unconstrained with regard to the distribution of motif occurrences within the input dataset. The algorithm is evaluated quantitatively on realistic synthetic data and several collections of characterized prokaryotic TFBS motifs and shown to outperform EM and an alternative sEM-based algorithm, particularly in terms of site-level positive predictive value. Availability and implementation: Java executable available for download at http://www.sourceforge.net/p/mitsu-motif/, supported on Linux/OS X. Contact: a.m.kilpatrick@sms.ed.ac.uk PMID:24931999

Kilpatrick, Alastair M.; Ward, Bruce; Aitken, Stuart

2014-01-01

473

Processamento auditivo e SPECT em crianças com dislexia  

Microsoft Academic Search

RESUMO - Aplicamos em um grupo de 36 crianças os testes dicótico de dígitos, dicótico de dissílabos altern a- dos e dicótico não-verbal, os quais fazem parte do conjunto de avaliação do processamento auditivo. As crianças foram divididas em dois grupos que foram correlacionados: grupo experimental (GE) formado por 18 crianças com diagnóstico de dislexia e 18 crianças normais compondo

Luciane Sauer; Liliane Desgualdo Pereira; Sylvia Maria Ciasca; Magda Pestun; Marilisa M. Guerreiro

2006-01-01

474

Standard Errors for EM Estimates in Generalized Linear Models with  

E-print Network

. As additional covariate among others the temperature was recorded. The bacteria content was determinedStandard Errors for EM Estimates in Generalized Linear Models with Random Effects Herwig Friedl of EM estimates in generalized linear models with random effects. Quadrature formulae are used

Friedl, Herwig

475

A Double Layer Electromagnetic Cloak And GL EM Modeling  

E-print Network

In this paper, we propose a novel electromagnetic (EM) cloaking structure that consists of two annular layers between three spherical shells and model its performance numerically and theoretically by using a Global and Local EM field (GL) method. The two annular layers contain distinct cloaking materials: the outer layer provides invisibility; the inner layer is fully absorbing. The cloaking materials are weakly degenerative. The wavefield from an EM source located outside the cloak propagates as in free space outside the outer shell, never be disturbed by the cloak and does not penetrate into the inner absorbing layer and concealment. The field of a source located inside inner layer or the cloaked concealment is completely absorbed by the inner layer and never reaches the outside of the middle shell, Moreover, the EM wavefield excited in concealment is not disrupted by the cloak. There exists no Maxwell EM wavefield can be excited in a single layer cloaked concealment which is filled by normal material. More...

Xie, Ganquan; Xie, Feng; Xie, Lee

2009-01-01

476

Electromagnetic optimization of EMS-MAGLEV systems  

SciTech Connect

In EMS-MAGLEV high-speed transport systems, devices for propulsion, levitation and contactless on-board electric power transfer are combined in a single electromagnetic structure. The strong coupling among the windings affects the performance of each device and requires the utilization of numerical codes. The paper describes an overall optimization procedure, based on a suitable mathematical model of the system, which takes into account several items of the system performance. The parameters of the model are calculated by an automated sequence of FEM analyses of the configuration. Both the linear generator output characteristics and the propulsion force ripple are improved applying the procedure to a reference configuration. The results are compared with the results obtained by a sequence of partial optimizations operating separately on two different subsets of the geometric parameters.

Andriollo, M.; Martinelli, G.; Morini, A.; Tortella, A. [Univ. of Padova (Italy). Dept. of Electrical Engineering] [Univ. of Padova (Italy). Dept. of Electrical Engineering

1998-07-01

477

DOE EM industry programs robotics development  

SciTech Connect

The Office of Science and Technology (OST) manages an aggressive program for RD&D, as well as testing and evaluation for the U.S. Department of Energy`s (DOE) Environmental Management (EM) organization. The goal is to develop new and improved environmental restoration and waste management technologies to clean up the inventory of the DOE weapons complex faster, safer, and cheaper than is possible with currently available technologies. OST has organized technology management activities along focus teams for each major problem area. There are currently five focus areas: decontamination and decommissioning, tanks, subsurface contaminants, mixed waste, and plutonium. In addition, OST is pursuing research and development (R&D) that cuts across these focus areas by having applications in two or more focus areas. Currently, there are three cross-cutting programs: the robotics technology development; characterization, monitoring, and sensor technologies; and efficient separations and processing.

Staubly, R.; Kothari, V. [Dept. of Energy, Morgantown, WV (United States)

1997-12-01

478

Evaluation of Fracture Azimuth by EM Wave and Elastic Wave  

NASA Astrophysics Data System (ADS)

Fracture system plays an important role in the development of underground energy, for example enhanced geothermal system (EGS), oil shale and shale gas, etc. Therefore, it becomes more and more important to detect and evaluate the fracture system. Geophysical prospecting is an useful method to evaluate the characteristics of the subsurface fractures. Currently, micro-seismology, multi-wave seismic exploration, and electromagnetic (EM) survey are reported to be used for the purpose. We are studying a method using both elastic wave and EM wave to detect and evaluate the fracture azimuth in laboratory. First, we build a 3D horizontal transverse isotropy (HTI) model, shown in the figure 1, by dry parallel fractures system, which was constructed by plexiglass plates and papers. Then, we used the ultrasonic system to obtain reflected S-wave data. Depending on the shear wave splitting, we evaluated the fracture azimuth by the algorithm of Pearson correlation coefficient. In addition, we used the full Polarimetric ultra wide band electromagnetic (FP-UWB-EM) wave System, shown in the figure 2, to obtain full polarimetric reflected EM-wave data. Depending on the rotation of the EM wave polarimetry, we evaluated the fracture azimuth by the the ration between maximum amplitude of co-polarimetric EM wave and maximum amplitude of cross-polarimetric EM wave. Finally, we used both EM-wave data and S-wave data to evaluate the fracture azimuth by the method of cross plot and statistical mathematics. To sum up, we found that FP-UWB-EM wave can be used to evaluated the fracture azimuth and is more accurate than ultrasound wave. Also joint evaluation using both data could improve the precision.

Feng, X.; Wang, Q.; Liu, C.; Lu, Q.; Zeng, Z.; Liang, W.; Yu, Y.; Ren, Q.

2013-12-01

479

Autonomia e Motivação em narrativas de aprendizes de português como língua estrangeira1  

Microsoft Academic Search

Neste artigo, discuto os resultados de minha pesquisa dentro do projeto AMFALE - Autonomia em um Modelo Fractal de Aquisição de Língua Estrangeira. Com base em conceitos de autonomia e motivação e na correlação entre eles, analiso narrativas de aprendizes de português como língua estrangeira em Belo Horizonte. Tais análises atestam que a experiência de aprendizagem inserida em uma comunidade

Fernanda Sousa Carvalho

480

Cultivo hidropônico de lisianto p ara flor de corte em sistema de fluxo laminar de nutrientes  

Microsoft Academic Search

Resumo - O objetivo deste trabalho foi avaliar as características produtivas e comerciais do cultivo de quatro cultivares de lisianto (Eustoma grandiflorum) em três soluções nutritivas em sistema de fluxo laminar de nutrientes (NFT). Utilizou-se o delineamento em blocos casualizados, em esquema fatorial 4x3, com três repetições. Os tratamentos foram compostos de quatro cultivares (Echo Champagne, Mariachi Pure White, Balboa

Alice Antonello; Londero Backes; José Geraldo Barbosa; Paulo Roberto Cecon; José Antonio Saraiva Grossi; Rogério Luiz Backes; Fernando Luiz Finger; Av. P. H. Rolfs

481

Transport quantique dans des nanostructures  

NASA Astrophysics Data System (ADS)

Quantum transport in nanostructures This work is devoted to the design, fabrication and magnetotransport investigations of mesoscopic devices. The sample are obtain by e-beam lithography and the measurements are performed at low temperature in a dilution refrigerator in the presence of a magnetic field. We have used MBE grown AlGaAs/GaAs heterojonctions as starting material to fabricate a bipartite tiling of rhombus called mathcal{T}3 lattice. We observe for the first time large amplitude h/e oscillations in this network as compared to the one measured in square lattices of similar size. These oscillations are the signature of a recently predited localization phenomenon induced by Aharonov-Bohm interferences on this peculiar topology. For particular values of the magnetic field the propagation of the electron wave function is bounded in a small number of cells, called Aharonov-Bohm cages. More strikingly, at high magnetic field, h/2e oscillations appear whose amplitude can be much higher than the fundamental period. Their temperature dependence is similar to that of the h/e signal. These observations withdraw a simple interpretation in terms of harmonics generation. The origin of this phenomenon is still unclear and needs more investigations. The influence electrical width of the wire defining the network and so the rule of the number of channels can be studied using a gate deposited over the lattice. In particular we have measured the amplitude dependence of the h/e and h/2e signal versus the gate voltage. Ce travail est consacré à la réalisation d'échantillons mésoscopiques à partir de la lithographie électronique ainsi qu'à leur caractérisation à très basse température en magnétotransport. Nous avons pour cela exploité le gaz bidimensionnel d'électrons situé à l'interface d'une hétérojonction AlGaAs/GaAs pour réaliser un réseau de boucle d'une géométrie particulière baptisée la géométrie mathcal{T}3. Nous avons observé sur cette structure des oscillations de conductance en fonction du flux du champ magnétique de période h/e dont l'amplitude est beaucoup plus importante que celle mesurée sur un réseau carré de même dimension. Cette différence constitue une signature d'un effet de localisation induit par le champ magnétique sur la topologie mathcal{T}3. Pour des valeurs spécifiques du champ magnétique, du fait des interférences destructives Aharonov-Bohm, la propagation des fonctions d'ondes est limitée à un ensemble fini de cellule du réseau appelé cage. De la dépendance en température des oscillations de période h/e mesurées sur le réseau mathcal{T}3 nous avons tiré une longueur caractéristique qui peut être rattachée au périmètre des cages. Un phénomène inattendu fut l'observation, pour des champs magnétiques plus importants, d'un doublement de fréquence des oscillations. Ces oscillations de période h/2e pouvant avoir une amplitude supérieure aux oscillations de période h/e, une interprétation en terme d'harmonique n'est pas possible. Enfin, l'influence de la largeur électrique des fils constituant le réseau et donc celle du nombre de canaux par brin a été étudiée en réalisant des grilles électrostatique. Les variations de l'amplitude des signaux en h/e et h/2e en fonction de la tension de grille ont été mesurés.

Naud, C.

2002-09-01

482

EM 9043 October 2011 Growing Farms: Successful Whole  

E-print Network

of the Oregon State University Extension Service Small Farms Program (http://smallfarms.oregonstate.edu) #12 ................................................................5 SWOT Analysis...............................................................7 Resource InventoryEM 9043 · October 2011 Growing Farms: Successful Whole Farm Management Planning Book Think It

Tullos, Desiree

483

Genética de populações e relações de parentesco em Ciconiiformes (Aves).  

E-print Network

??Estudos de genética de populações e de parentesco genético foram desenvolvidos em colhereiro (Platalea ajaja), cabeça-seca (Mycteria americana) e garça-branca-grande (Ardea alba egretta), de colônias… (more)

Carolina Isabel Miño

2010-01-01

484

Structure of Matter, Forces, EM Waves, Spectroscopy, Doppler Effect  

NSDL National Science Digital Library

These supplemental class notes cover the basic properties of matter, the nature of forces, the electromagnetic spectrum, and how astronomers exploit the properties of the EM spectrum to deduce the physical nature of distant objects.

O'Connell, Robert

2005-06-28

485

An Innovative Tool to Assist in Rural EMS Response  

E-print Network

technologies for EMS -NextGeneration 911 -IP telephony -AACN -Mobile phones -Computer Aided Dispatch (CAD) -GPS (security & privacy) !Users must want to use it, be able to use it, like to use it !Leverage growth

Minnesota, University of

486

An Effective EMS Hardware and Software Interface- The Trained Operator  

E-print Network

you have es tablished operator training objectives, selecting appropriate training methods becomes easier. OPERATOR SKILL CATEGORIES Identifying and defining your EMS instructional objectives can be a fairly straightforward process. There is a... ings are minimal. An operator needs the full capability of being able to address all the EMS features and related individ ual building functions. Can you see the results of having a fully trained operator? Less personal frustration, improved use...

Cherry, C. L.

487

EM clustering analysis of diabetes patients basic diagnosis index.  

PubMed

Cluster analysis can group similar instances into same group and different instances into different groups. It assigns classes to samples without known the classes in advance. EM clustering algorithm can find number of distributions of generating data and build "mixture models". It identifies groups that are either overlapping or varying sizes and shapes. In this project, by using EM in Weka system, diabetes patient basic diagnosis index data have been analyzed for clustering. PMID:16779444

Wu, Cai; Steinbauer, Jeffrey R; Kuo, Grace M

2005-01-01

488

EM algorithm estimation of TCM scheme over multipath fading  

E-print Network

estimate is available to the receiver. B. Previous Research The following are some studies in application of EM algorithm in a, communicat, ion problem. Han and Georghiades [I] investigated the application of EM algorithm to t, he optimum receiver... 4. In Sections A and C, the structure of encoder an&i decoder implemented in the simulation is described. We described how the fading model is simulated in Section B. A. Transmitter A transmitter used in this study employs Ungerboeck's 8-state...

Gunawan, Wiedy

2012-06-07

489

Users of midwest EMS firm stuck without software  

SciTech Connect

Four midwest energy management system (EMS) users report delays in software delivery and a failure to achieve energy savings with National Control Systems Inc. (NCS) equipment. A fifth user has already replaced an unsatisfactory NCS system. Representatives of the users relate their experiences in trying to make the EMS systems works and to acquire the necessary software beyond the original start/stop functions. Most expect to deal with larger, more established companies in the future. (DCK)

Galvin, C.

1983-07-18

490

NASA EM Followup of LIGO-Virgo Candidate Events  

NASA Technical Reports Server (NTRS)

We present a strategy for a follow-up of LIGO-Virgo candidate events using offline survey data from several NASA high-energy photon instruments aboard RXTE, Swift, and Fermi. Time and sky-location information provided by the GW trigger allows for a targeted search for prompt and afterglow EM signals. In doing so, we expect to be sensitive to signals which are too weak to be publicly reported as astrophysical EM events.

Blackburn, Lindy L.

2011-01-01

491

DOE EM industry programs robotics development  

SciTech Connect

The Office of Science and Technology (OST) manages an aggressive program for RD and D, as well as testing and evaluation for the Department of Energy`s (DOE`s) Environmental Management (EM) organization. The goal is to develop new and improved environmental restoration and waste management technologies to clean up the inventory of the DOE weapons complex faster, safer, and cheaper than is possible with currently available technologies. Robotic systems reduce worker exposure to the absolute minimum, while providing proven, cost-effective, and, for some applications, the only acceptable technique for addressing challenging problems. Development of robotic systems for remote operations occurs in three main categories: tank waste characterization and retrieval; decontamination and dismantlement; and characterization, mapping, and inspection systems. In addition, the Federal Energy Technology Center (FETC) has some other projects which fall under the heading of supporting R and D. The central objective of all FETC robotic projects is to make robotic systems more attractive by reducing costs and health risks associated with the deployment of robotic technologies in the cleanup of the nuclear weapons complex. This will be accomplished through development of robots that are cheaper, faster, safer, and more reliable, as well as more straightforward to modify/adapt and more intuitive to operate with autonomous capabilities and intelligent controls that prevent accidents and optimize task execution.

Staubly, R.; Kothari, V.

1998-12-31

492

EM Task 9 - Centrifugal Membrane Filtration  

SciTech Connect

This project is designed to establish the utility of a novel centrifugal membrane filtration technology for the remediation of liquid mixed waste streams at US Department of Energy (DOE) facilities in support of the DOE Environmental Management (EM) program. The Energy and Environmental Research Center (EERC) has teamed with SpinTek Membrane Systems, Inc., a small business and owner of the novel centrifugal membrane filtration technology, to establish the applicability of the technology to DOE site remediation and the commercial viability of the technology for liquid mixed waste stream remediation. The technology is a uniquely configured process that makes use of ultrafiltration and centrifugal force to separate suspended and dissolved solids from liquid waste streams, producing a filtered water stream and a low-volume contaminated concentrate stream. This technology has the potential for effective and efficient waste volume minimization, the treatment of liquid tank wastes, the remediation of contaminated groundwater plumes, and the treatment of secondary liquid waste streams from other remediation processes, as well as the liquid waste stream generated during decontamination and decommissioning activities.

Stevens, B.G.; Stepan, D.J.; Hetland, M.D.

1998-11-01

493

Isolamento de Salmonella spp. em pombos (Columba livia) no Distrito Federal : aspecto de relevância ao sistema de vigilância em saúde.  

E-print Network

??Dissertação (mestrado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, Programa de Pós-Graduação em Saúde Animal, 2014. A domesticação de pombos da espécie Columba livia,… (more)

Santos, Ivanildo de Oliveira Correia

2014-01-01

494

Condensação de Bose-Einstein para um gás de bósons não interagentes em confinamentos bidimensionais em automatos celulares complexos.  

E-print Network

??Neste trabalho estudamos as propriedades termodinâmicas da Condensação de Bose-Einstein (CBE) para um gás de bósons não-interagentes confinado em potenciais bidimensionais V(x,y) que apresentam classicamente,… (more)

Daniel Schardosim Calovi

2007-01-01

495

STF mantm cobrana de taxa para inscrio em vestibular A Procuradoria-Geral Federal em atuao conjunta com a Procuradoria Regional  

E-print Network

STF mantém cobrança de taxa para inscrição em vestibular A Procuradoria-Geral Federal em atuação sustentava a constitucionalidade da cobrança da taxa de vestibular. Ao apreciar o caso, a Ministra Ellen a de inscrição em vestibular. Fonte: STF #12;

Floeter, Sergio Ricardo

496

Astronomia para/com crianças carentes em Limeira  

NASA Astrophysics Data System (ADS)

Em 2001, o Instituto Superior de Ciências Aplicadas (ISCA Faculdades de Limeira) iniciou um projeto pelo qual o Observatório do Morro Azul empreendeu uma parceria com o Centro de Promoção Social Municipal (CEPROSOM), instituição mantida pela Prefeitura Municipal de Limeira para atender crianças e adolescentes carentes. O CEPROSOM contava com dois projetos: Projeto Centro de Convivência Infantil (CCI) e Programa Criança e Adolescente (PCA), que atendiam crianças e adolescentes em Centros Comunitários de diversas áreas da cidade. Esses projetos têm como prioridades estabelecer atividades prazerosas para as crianças no sentido de retirá-las das ruas. Assim sendo, as crianças passaram a ter mais um tipo de atividade - as visitas ao observatório. Este painel descreve as várias fases do projeto, que envolveu: reuniões de planejamento, curso de Astronomia para as orientadoras dos CCIs e PCAs, atividades relacionadas a visitas das crianças ao Observatório, proposta de construção de gnômons e relógios de Sol nos diversos Centros Comunitários de Limeira e divulgação do projeto na imprensa. O painel inclui discussões sobre a aprendizagem de crianças carentes, relatos que mostram a postura das orientadoras sobre a pertinência do ensino de Astronomia, relatos do monitor que fez o atendimento no Observatório e o que o número de crianças atendidas representou para as atividades da instituição desde o início de suas atividades e, em particular, em 2001. Os resultados são baseados na análise de relatos das orientadoras e do monitor do Observatório, registros de visitas e matérias da imprensa local. Conclui com uma avaliação do que tal projeto representou para as Instituições participantes. Para o Observatório, em particular, foi feita uma análise com relação às outras modalidades de atendimentos que envolvem alunos de escolas e público em geral. Também é abordada a questão do compromisso social do Observatório na educação do público em questão.

Bretones, P. S.; Oliveira, V. C.

2003-08-01

497

Efficient injection of spin-polarized electrons from manganese arsenide contacts into aluminum gallium arsenide/gallium arsenide spin LEDs  

NASA Astrophysics Data System (ADS)

In this thesis we describe two spectroscopic projects project on semiconductor heterostructures, as well as putting together and testing a micro-photoluminescence/7 tesla magnet system for the study of micron size two-dimensional crystals. Below we discuss the three parts in more detail. i) MnAs-based spin light emitting diodes. We have studied the injection of spin-polarized electrons from a ferromagnetic MnAs contact into an AlGaAs(n)/GaAs(i)/AlGaAs(p) n-i-p light emitting diode. We have recorder the emitted electroluminescence as function of magnetic field applied at right angles to the device plane in the 7-300 K temperature range. It was found that at 7 Kelvin the emitted light is circularly polarized with a polarization that is proportional to the MnAs contact magnetization with a saturation value of 26% for B > 1.25 tesla. The polarization persists up to room temperature with a saturation value of 6%. ii) Optical Aharonov-Bohm effect in InGaAs quantum wells. The excitonic photoluminescence intensity from InGaAs quantum wells as function of magnetic field exhibits two local maxima superimposed on a decreasing background. The maxima are attributed to the optical Aharonov-Bohm effect of electrons orbiting around a hole localized at the center of an Indium rich InGaAs islands detected by cross sectional scanning tunneling microscopy. Analysis of the position of the maxima yields a value of the electron orbit radius. iii) Micro-Photoluminescence. We have put together a micro-photoluminescence /7 tesla system for the study of two dimensional crystals. The samples are placed inside a continuous flow cryostat whose tail is positioned in the bore of the 7 tesla magnet. A microscope objective is used to focus the exciting laser light and collect the emitted photoluminescence. The system was tested by recording the photoluminescence spectra of WS2 and WSe 2 monolayers at T = 77 K.

Schweidenback, Lars

498

Propulsion From a Rotating EM Tether at Jupiter  

NASA Technical Reports Server (NTRS)

The Jovian system with its rapid planetary rotation and strong magnetic field presents exciting opportunities for the use of electrodynamic (EM) tethers. Previous analysis for a radial, 10 km length tether demonstrated the possibility of propulsive forces as large as 50 Newtons near the planet. For orbital positions beyond about 2.5 Jovian radii, an EM tether can simultaneously be used for power and increases in the orbital altitude. Although the previous study demonstrated the physical feasibility of EM tether use at Jupiter, it did not address the issues of limited gravity gradient force for tether orientation and the practical use of this technology in an engineered system. This presentation will discuss these issues and current progress in an ongoing science/engineering transitional study.

Gallagher, D. L.; Moore, J.

2000-01-01

499

Longitudinal information and radiation damage in EM calorimetry  

SciTech Connect

The SCC radiation field is higher than that encountered by previous hadron collider detectors. In particular, the electromagnetic (EM) calorimeter compartment sees the highest radiation dose. Since an EM calorimeter also makes the most precise energy measurement, special care must be lavished on this part of a calorimeter. Previous studies have concentrated on Monte Carlo examinations of 2 longitudinal compartments within the EM which can alleviate radiation damage. Recently, it was realized that a ``shower maximum`` detector, such as exists in CDF, also contains information of the conversion point of an electromagnetic shower. As such, it can potentially be used in a fashion analogous to the longitudinal compartments, although it is not designed to be optimized for this role.

Green, D.

1993-02-05

500

Longitudinal information and radiation damage in EM calorimetry  

SciTech Connect

The SCC radiation field is higher than that encountered by previous hadron collider detectors. In particular, the electromagnetic (EM) calorimeter compartment sees the highest radiation dose. Since an EM calorimeter also makes the most precise energy measurement, special care must be lavished on this part of a calorimeter. Previous studies have concentrated on Monte Carlo examinations of 2 longitudinal compartments within the EM which can alleviate radiation damage. Recently, it was realized that a shower maximum'' detector, such as exists in CDF, also contains information of the conversion point of an electromagnetic shower. As such, it can potentially be used in a fashion analogous to the longitudinal compartments, although it is not designed to be optimized for this role.

Green, D.

1993-02-05