Unconventional Integer Quantum Hall effect in graphene
V. P. Gusynin; S. G. Sharapov
2005-08-16T23:59:59.000Z
Monolayer graphite films, or graphene, have quasiparticle excitations that can be described by 2+1 dimensional Dirac theory. We demonstrate that this produces an unconventional form of the quantized Hall conductivity $\\sigma_{xy} = - (2 e^2/h)(2n+1)$ with $n=0,1,...$, that notably distinguishes graphene from other materials where the integer quantum Hall effect was observed. This unconventional quantization is caused by the quantum anomaly of the $n=0$ Landau level and was discovered in recent experiments on ultrathin graphite films.
The Quantum Hall Effect in Graphene
Paolo Cea
2012-04-24T23:59:59.000Z
We investigate the quantum Hall effect in graphene. We argue that in graphene in presence of an external magnetic field there is dynamical generation of mass by a rearrangement of the Dirac sea. We show that the mechanism breaks the lattice valley degeneracy only for the $n=0$ Landau levels and leads to the new observed $\
Integer Quantum Hall Effect in Graphene
Jellal, Ahmed
2015-01-01T23:59:59.000Z
We study the quantum Hall effect in a monolayer graphene by using an approach based on thermodynamical properties. This can be done by considering a system of Dirac particles in an electromagnetic field and taking into account of the edges effect as a pseudo-potential varying continuously along the $x$ direction. At low temperature and in the weak electric field limit, we explicitly determine the thermodynamical potential. With this, we derive the particle numbers in terms of the quantized flux and therefore the Hall conductivity immediately follows.
Integer Quantum Hall Effect in Graphene
Ahmed Jellal
2015-04-24T23:59:59.000Z
We study the quantum Hall effect in a monolayer graphene by using an approach based on thermodynamical properties. This can be done by considering a system of Dirac particles in an electromagnetic field and taking into account of the edges effect as a pseudo-potential varying continuously along the $x$ direction. At low temperature and in the weak electric field limit, we explicitly determine the thermodynamical potential. With this, we derive the particle numbers in terms of the quantized flux and therefore the Hall conductivity immediately follows.
Ezawa, Motohiko [Department of Applied Physics, University of Tokyo, Hongo 7-3-1, Tokyo 113-8656 (Japan)
2013-12-04T23:59:59.000Z
Silicene is a monolayer of silicon atoms forming a two-dimensional honeycomb lattice, which shares almost every remarkable property with graphene. The low energy dynamics is described by Dirac electrons, but they are massive due to relatively large spin-orbit interactions. I will explain the following properties of silicene: 1) The band structure is controllable by applying an electric field. 2) Silicene undergoes a phase transition from a topological insulator to a band insulator by applying external electric field. 3) The topological phase transition can be detected experimentally by way of diamagnetism. 4) There is a novel valley-spin selection rules revealed by way of photon absorption. 5) Silicene yields a remarkably many phases such as quantum anomalous Hall phase and valley polarized metal when the exchange field is additionally introduced. 6) A silicon nanotubes can be used to convey spin currents under an electric field.
Quantum Anomalous Hall Effect in Hg_1-yMn_yTe Quantum Wells
Liu, Chao-Xing; /Tsinghua U., Beijing /Stanford U., Phys. Dept.; Qi, Xiao-Liang; /Stanford U., Phys. Dept.; Dai, Xi; Fang, Zhong; /Beijing, Inst. Phys.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.
2010-03-19T23:59:59.000Z
The quantum Hall effect is usually observed when the two-dimensional electron gas is subjected to an external magnetic field, so that their quantum states form Landau levels. In this work we predict that a new phenomenon, the quantum anomalous Hall effect, can be realized in Hg{sub 1-y}Mn{sub y}Te quantum wells, without the external magnetic field and the associated Landau levels. This effect arises purely from the spin polarization of the Mn atoms, and the quantized Hall conductance is predicted for a range of quantum well thickness and the concentration of the Mn atoms. This effect enables dissipationless charge current in spintronics devices.
Strong Correlation Effects in Graphene in the Quantum Hall Regime
Paris-Sud 11, Université de
Strong Correlation Effects in Graphene in the Quantum Hall Regime Mark Oliver Goerbig 16 June 2008;Graphene = 2D Graphite 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 degeneracy: spin valley Energy electrons holes k k k ky x x yK' K K' K K K' #12;Correlations in graphene
Supersymmetry and Unconventional Quantum Hall Effect in Graphene
Motohiko Ezawa
2006-06-03T23:59:59.000Z
We present a unified description of the quantum Hall effect in graphene on the basis of the 8-component Dirac Hamiltonian and the supersymmetric (SUSY) quantum mechanics. It is remarkable that the zero-energy state emerges because the Zeeman splitting is exactly as large as the Landau level separation, as implies that the SUSY is a good symmetry. For nonzero energy states, the up-spin state and the down-spin state form a supermultiplet possessing the spin SU(2) symmetry. We extend the Dirac Hamiltonian to include two indices $j_{\\uparrow}$ and $j_{\\downarrow}$, characterized by the dispersion relation $E(p) \\propto p^{j_{\\uparrow}+j_{\\downarrow}}$ and the Berry phase $\\pi (j_{\\uparrow}-j_{\\downarrow})$. The quantized Hall conductivity is shown to be $\\sigma_{xy}=\\pm (2n+j_{\\uparrow}+j_{\\downarrow}) 2e^{2}/h$.
Intrinsic Spin Hall Effect Induced by Quantum Phase Transition in HgCdTe Quantum Wells
Yang, Wen; Chang, Kai; /Beijing, Inst. Semiconductors; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.
2010-03-19T23:59:59.000Z
Spin Hall effect can be induced both by the extrinsic impurity scattering and by the intrinsic spin-orbit coupling in the electronic structure. The HgTe/CdTe quantum well has a quantum phase transition where the electronic structure changes from normal to inverted. We show that the intrinsic spin Hall effect of the conduction band vanishes on the normal side, while it is finite on the inverted side. This difference gives a direct mechanism to experimentally distinguish the intrinsic spin Hall effect from the extrinsic one.
Quantum spin Hall effect in nanostructures based on cadmium fluoride
Bagraev, N. T., E-mail: Bagraev@mail.ioffe.ru [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Guimbitskaya, O. N. [St. Petersburg State Polytechnical University (Russian Federation); Klyachkin, L. E.; Koudryavtsev, A. A.; Malyarenko, A. M. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Romanov, V. V. [St. Petersburg State Polytechnical University (Russian Federation); Ryskin, A. I.; Shcheulin, A. S. [St. Petersburg State University of Information Technologies, Mechanics, and Optics (Russian Federation)
2010-10-15T23:59:59.000Z
Tunneling current-voltage (I-V) characteristics and temperature dependences of static magnetic susceptibility and specific heat of the CdB{sub x}F{sub 2-x}/p-CdF{sub 2}-QW/CdB{sub x}F{sub 2-x} planar sandwich structures formed on the surface of an n-CdF{sub 2} crystal have been studied in order to identify superconducting properties of the CdB{sub x}F{sub 2-x} {delta} barriers confining the p-type CdF{sub 2} ultranarrow quantum well. Comparative analysis of current-voltage (I-V) characteristics and conductance-voltage dependences (measured at the temperatures, respectively, below and above the critical temperature of superconducting transition) indicates that there is an interrelation between quantization of supercurrent and dimensional quantization of holes in the p-CdF{sub 2} ultranarrow quantum well. It is noteworthy that detection of the Josephson peak of current in each hole subband is accompanied by the appearance of the spectrum of the multiple Andreev reflection (MAR). A high degree of spin polarization of holes in the edge channels along the perimeter of the p-CdF{sub 2} ultranarrow quantum well appears as a result of MAR and makes it possible to identify the quantum spin Hall effect I-V characteristics; this effect becomes pronounced in the case of detection of nonzero conductance at the zero voltage applied to the vertical gate in the Hall geometry of the experiment. Within the energy range of superconducting gap, the I-V characteristics of the spin transistor and quantum spin Hall effect are controlled by the MAR spectrum appearing as the voltage applied to the vertical gate is varied. Beyond the range of the superconducting gap, the observed I-V characteristic of the quantum spin Hall effect is represented by a quantum conductance staircase with a height of the steps equal to e{sub 2}/h; this height is interrelated with the Aharonov-Casher oscillations of longitudinal and depends on the voltage applied to the vertical gate.
The integer quantum hall effect revisited
Michalakis, Spyridon [Los Alamos National Laboratory; Hastings, Matthew [Q STATION, CALIFORNIA
2009-01-01T23:59:59.000Z
For T - L x L a finite subset of Z{sup 2}, let H{sub o} denote a Hamiltonian on T with periodic boundary conditions and finite range, finite strength intetactions and a unique ground state with a nonvanishing spectral gap. For S {element_of} T, let q{sub s} denote the charge at site s and assume that the total charge Q = {Sigma}{sub s {element_of} T} q{sub s} is conserved. Using the local charge operators q{sub s}, we introduce a boundary magnetic flux in the horizontal and vertical direction and allow the ground state to evolve quasiadiabatically around a square of size one magnetic flux, in flux space. At the end of the evolution we obtain a trivial Berry phase, which we compare, via a method reminiscent of Stokes Theorem. to the Berry phase obtained from an evolution around an exponentially small loop near the origin. As a result, we show, without any averaging assumption, that the Hall conductance is quantized in integer multiples of e{sup 2}/h up to exponentially small corrections of order e{sup -L/{zeta}}, where {zeta}, is a correlation length that depends only on the gap and the range and strength of the interactions.
The Quantum Spin Hall Effect: Theory and Experiment
Konig, Markus; Buhmann, Hartmut; Molenkamp, Laurens W.; /Wurzburg U.; Hughes, Taylor L.; /Stanford U., Phys. Dept.; Liu, Chao-Xing; /Tsinghua U., Beijing /Stanford U., Phys. Dept.; Qi, Xiao-Liang; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.
2010-03-19T23:59:59.000Z
The search for topologically non-trivial states of matter has become an important goal for condensed matter physics. Recently, a new class of topological insulators has been proposed. These topological insulators have an insulating gap in the bulk, but have topologically protected edge states due to the time reversal symmetry. In two dimensions the helical edge states give rise to the quantum spin Hall (QSH) effect, in the absence of any external magnetic field. Here we review a recent theory which predicts that the QSH state can be realized in HgTe/CdTe semiconductor quantum wells. By varying the thickness of the quantum well, the band structure changes from a normal to an 'inverted' type at a critical thickness d{sub c}. We present an analytical solution of the helical edge states and explicitly demonstrate their topological stability. We also review the recent experimental observation of the QSH state in HgTe/(Hg,Cd)Te quantum wells. We review both the fabrication of the sample and the experimental setup. For thin quantum wells with well width d{sub QW} < 6.3 nm, the insulating regime shows the conventional behavior of vanishingly small conductance at low temperature. However, for thicker quantum wells (d{sub QW} > 6.3 nm), the nominally insulating regime shows a plateau of residual conductance close to 2e{sup 2}/h. The residual conductance is independent of the sample width, indicating that it is caused by edge states. Furthermore, the residual conductance is destroyed by a small external magnetic field. The quantum phase transition at the critical thickness, d{sub c} = 6.3 nm, is also independently determined from the occurrence of a magnetic field induced insulator to metal transition.
Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
Bernevig, A.
2010-03-02T23:59:59.000Z
We show that the quantum spin Hall (QSH) effect, a state of matter with topological properties distinct from those of conventional insulators, can be realized in mercury telluride-cadmium telluride semiconductor quantum wells. When the thickness of the quantum well is varied, the electronic state changes from a normal to an 'inverted' type at a critical thickness d{sub c}. We show that this transition is a topological quantum phase transition between a conventional insulating phase and a phase exhibiting the QSH effect with a single pair of helical edge states. We also discuss methods for experimental detection of the QSH effect.
Topological superconductivity, topological confinement, and the vortex quantum Hall effect
Diamantini, M. Cristina; Trugenberger, Carlo A. [INFN and Dipartimento di Fisica, University of Perugia, via A. Pascoli, I-06100 Perugia (Italy); SwissScientific, chemin Diodati 10, CH-1223 Cologny (Switzerland)
2011-09-01T23:59:59.000Z
Topological matter is characterized by the presence of a topological BF term in its long-distance effective action. Topological defects due to the compactness of the U(1) gauge fields induce quantum phase transitions between topological insulators, topological superconductors, and topological confinement. In conventional superconductivity, because of spontaneous symmetry breaking, the photon acquires a mass due to the Anderson-Higgs mechanism. In this paper we derive the corresponding effective actions for the electromagnetic field in topological superconductors and topological confinement phases. In topological superconductors magnetic flux is confined and the photon acquires a topological mass through the BF mechanism: no symmetry breaking is involved, the ground state has topological order, and the transition is induced by quantum fluctuations. In topological confinement, instead, electric charge is linearly confined and the photon becomes a massive antisymmetric tensor via the Stueckelberg mechanism. Oblique confinement phases arise when the string condensate carries both magnetic and electric flux (dyonic strings). Such phases are characterized by a vortex quantum Hall effect potentially relevant for the dissipationless transport of information stored on vortices.
Quantum spin Hall effect and topological insulators for light
Bliokh, Konstantin Y
2015-01-01T23:59:59.000Z
We show that free-space light has intrinsic quantum spin-Hall effect (QSHE) properties. These are characterized by a non-zero topological spin Chern number, and manifest themselves as evanescent modes of Maxwell equations. The recently discovered transverse spin of evanescent modes demonstrates spin-momentum locking stemming from the intrinsic spin-orbit coupling in Maxwell equations. As a result, any interface between free space and a medium supporting surface modes exhibits QSHE of light with opposite transverse spins propagating in opposite directions. In particular, we find that usual isotropic metals with surface plasmon-polariton modes represent natural 3D topological insulators for light. Several recent experiments have demonstrated transverse spin-momentum locking and spin-controlled unidirectional propagation of light at various interfaces with evanescent waves. Our results show that all these experiments can be interpreted as observations of the QSHE of light.
Quantum Hall effect and Landau-level crossing of Dirac fermions in trilayer graphene
Taychatanapat, Thiti
The physics of Dirac fermions in condensed-matter systems has received extraordinary attention following the discoveries of two new types of quantum Hall effect in single-layer and bilayer graphene1, 2, 3. The electronic ...
Toward theory of quantum Hall effect in graphene
E. V. Gorbar; V. P. Gusynin; V. A. Miransky
2008-11-07T23:59:59.000Z
We analyze a gap equation for the propagator of Dirac quasiparticles and conclude that in graphene in a magnetic field, the order parameters connected with the quantum Hall ferromagnetism dynamics and those connected with the magnetic catalysis dynamics necessarily coexist (the latter have the form of Dirac masses and correspond to excitonic condensates). This feature of graphene could lead to important consequences, in particular, for the existence of gapless edge states. Solutions of the gap equation corresponding to recently experimentally discovered novel plateaus in graphene in strong magnetic fields are described.
Title: Electron-Hole Asymmetric Integer and Fractional Quantum Hall Effect in Bilayer Graphene
Yacoby, Amir
Title: Electron-Hole Asymmetric Integer and Fractional Quantum Hall Effect in Bilayer Graphene graphene is predicted to pro- duce novel and tunable FQH ground states. Here we present local electronic compressibility measurements of the FQH effect in the lowest Landau level of bilayer graphene. We observe
arXiv:cond-mat/0411737v223Nov2005 Quantum Spin Hall Effect in Graphene
Cobden, David
reported progress in the preparation of single layer graphene films. These films exhibit the expectedarXiv:cond-mat/0411737v223Nov2005 Quantum Spin Hall Effect in Graphene C.L. Kane and E.J. Mele Dept orbit interactions on the low energy electronic structure of a sin- gle plane of graphene. We find
Quantum Spin Hall Effect in Graphene C. L. Kane and E. J. Mele
Kane, Charles
reported progress in the preparation of single layer graphene films. These films exhibit the expectedQuantum Spin Hall Effect in Graphene C. L. Kane and E. J. Mele Dept. of Physics and Astronomy of a single plane of graphene. We find that in an experimentally accessible low temperature regime
Non-Commutative Geometry in Higher Dimensional Quantum Hall Effect as A-Class Topological Insulator
Kazuki Hasebe
2014-08-04T23:59:59.000Z
We clarify relations between the higher dimensional quantum Hall effect and A-class topological insulator. In particular, we elucidate physical implications of the higher dimensional non-commutative geometry in the context of A-class topological insulator. This presentation is based on arXiv:1403.5066.
Electrical Readout of the Local Nuclear Polarization in the Quantum Hall Effect: A Hyperfine Battery
Lorke, Axel
Electrical Readout of the Local Nuclear Polarization in the Quantum Hall Effect: A Hyperfine Battery A. WuÂ¨rtz,1,* T. MuÂ¨ller,1 A. Lorke,1, D. Reuter,2 and A. D. Wieck2 1 Laboratorium fuÂ¨r Festko which utilizes separately contacted edge states to establish a local nuclear spin polarization
Half integer quantum Hall effect in high mobility single layer epitaxial graphene
Half integer quantum Hall effect in high mobility single layer epitaxial graphene Xiaosong Wu,1 of is demonstrated here on a single graphene layer grown on the C-face of 4H silicon carbide. The mobility is 20 000. This is comparable to the best exfoliated graphene flakes on SiO2 and an order of magnitude larger than Si
Interface engineering of quantum Hall effects in digital transition metal oxide heterostructures
Xiao, Di [ORNL; Zhu, Wenguang [University of Tennessee, Knoxville (UTK); Ran, Ying [Boston College, Chestnut Hill; Nagaosa, Naoto [University of Tokyo, Tokyo, Japan; Okamoto, Satoshi [ORNL
2011-01-01T23:59:59.000Z
Topological insulators (TIs) are characterized by a non-trivial band topology driven by the spin-orbit coupling. To fully explore the fundamental science and application of TIs, material realization is indispensable. Here we predict, based on tight-binding modeling and first-principles calculations, that bilayers of perovskite-type transition-metal oxides grown along the [111] crystallographic axis are potential candidates for two-dimensional TIs. The topological band structure of these materials can be fine-tuned by changing dopant ions, substrates and external gate voltages. We predict that LaAuO$_3$ bilayers have a topologically non-trivial energy gap of about 0.15~eV, which is sufficiently large to realize the quantum spin Hall effect at room temperature. Intriguing phenomena, such as fractional quantum Hall effect, associated with the nearly flat topologically non-trivial bands found in $e_g$ systems are also discussed.
Excitonic gap, phase transition, and quantum Hall effect in graphene
V. P. Gusynin; V. A. Miransky; S. G. Sharapov; I. A. Shovkovy
2006-11-23T23:59:59.000Z
We suggest that physics underlying the recently observed removal of sublattice and spin degeneracies in graphene in a strong magnetic field describes a phase transition connected with the generation of an excitonic gap. The experimental form of the Hall conductivity is reproduced and the main characteristics of the dynamics are described. Predictions of the behavior of the gap as a function of temperature and a gate voltage are made.
Coulomb interaction and magnetic catalysis in the quantum Hall effect in graphene
E. V. Gorbar; V. P. Gusynin; V. A. Miransky; I. A. Shovkovy
2012-02-01T23:59:59.000Z
The dynamics of symmetry breaking responsible for lifting the degeneracy of the Landau levels in the integer quantum Hall effect in graphene is studied in a low-energy model with the Coulomb interaction. The gap equation for Dirac quasiparticles is analyzed for both the lowest and higher Landau levels, taking into account the Landau levels mixing. It is shown that the characteristic feature of the long-range Coulomb interaction is the decrease of the gap parameters with increasing the Landau level index $n$ ("running" gaps). The renormalization (running) of the Fermi velocity as a function of $n$ is also studied. The solutions of the gap equation reproduce correctly the experimentally observed integer quantum Hall plateaus in graphene in strong magnetic fields.
Field effect in the quantum Hall regime of a high mobility graphene wire
Barraud, C., E-mail: cbarraud@phys.ethz.ch, E-mail: clement.barraud@univ-paris-diderot.fr; Choi, T.; Ihn, T.; Ensslin, K. [Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich (Switzerland); Butti, P.; Shorubalko, I. [Swiss Federal Laboratories of Materials Science and Technologies, EMPA Elect. Metrol. Reliabil. Lab., CH-8600 Dübendorf (Switzerland); Taniguchi, T.; Watanabe, K. [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan)
2014-08-21T23:59:59.000Z
In graphene-based electronic devices like in transistors, the field effect applied thanks to a gate electrode allows tuning the charge density in the graphene layer and passing continuously from the electron to the hole doped regime across the Dirac point. Homogeneous doping is crucial to understand electrical measurements and for the operation of future graphene-based electronic devices. However, recently theoretical and experimental studies highlighted the role of the electrostatic edge due to fringing electrostatic field lines at the graphene edges [P. Silvestrov and K. Efetov, Phys. Rev. B 77, 155436 (2008); F. T. Vasko and I. V. Zozoulenko, Appl. Phys. Lett. 97, 092115 (2010)]. This effect originates from the particular geometric design of the samples. A direct consequence is a charge accumulation at the graphene edges giving a value for the density, which deviates from the simple picture of a plate capacitor and also varies along the width of the graphene sample. Entering the quantum Hall regime would, in principle, allow probing this accumulation thanks to the extreme sensitivity of this quantum effect to charge density and the charge distribution. Moreover, the presence of an additional and counter-propagating edge channel has been predicted [P. Silvestrov and K. Efetov, Phys. Rev. B 77, 155436 (2008)] giving a fundamental aspect to this technological issue. In this article, we investigate this effect by tuning a high mobility graphene wire into the quantum Hall regime in which charge carriers probe the electrostatic potential at high magnetic field close to the edges. We observe a slight deviation to the linear shift of the quantum Hall plateaus with magnetic field and we study its evolution for different filling factors, which correspond to different probed regions in real space. We discuss the possible origins of this effect including an increase of the charge density towards the edges.
Position-Momentum Duality and Fractional Quantum Hall Effect in Chern Insulators
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Claassen, Martin [SLAC National Accelerator Lab., Menlo Park, CA (United States); Lee, Ching-Hua [Stanford Univ., CA (United States); Thomale, Ronny [Univ. of Wurzburg (Germany); Qi, Xiao-Liang [Stanford Univ., CA (United States); Devereaux, Thomas P [SLAC National Accelerator Lab., Menlo Park, CA (United States)
2015-06-01T23:59:59.000Z
We develop a first quantization description of fractional Chern insulators that is the dual of the conventional fractional quantum Hall (FQH) problem, with the roles of position and momentum interchanged. In this picture, FQH states are described by anisotropic FQH liquids forming in momentum-space Landau levels in a fluctuating magnetic field. The fundamental quantum geometry of the problem emerges from the interplay of single-body and interaction metrics, both of which act as momentum-space duals of the geometrical picture of the anisotropic FQH effect. We then present a novel broad class of ideal Chern insulator lattice models that act as duals of the isotropic FQH effect. The interacting problem is well-captured by Haldane pseudopotentials and affords a detailed microscopic understanding of the interplay of interactions and non-trivial quantum geometry.
Higher Dimensional Quantum Hall Effect as A-Class Topological Insulator
Kazuki Hasebe
2014-08-02T23:59:59.000Z
We perform a detail study of higher dimensional quantum Hall effects and A-class topological insulators with emphasis on their relations to non-commutative geometry. There are two different formulations of non-commutative geometry for higher dimensional fuzzy spheres; the ordinary commutator formulation and quantum Nambu bracket formulation. Corresponding to these formulations, we introduce two kinds of monopole gauge fields; non-abelian gauge field and antisymmetric tensor gauge field, which respectively realize the non-commutative geometry of fuzzy sphere in the lowest Landau level. We establish connection between the two types of monopole gauge fields through Chern-Simons term, and derive explicit form of tensor monopole gauge fields with higher string-like singularity. The connection between two types of monopole is applied to generalize the concept of flux attachment in quantum Hall effect to A-class topological insulator. We propose tensor type Chern-Simons theory as the effective field theory for membranes in A-class topological insulators. Membranes turn out to be fractionally charged objects and the phase entanglement mediated by tensor gauge field transforms the membrane statistics to be anyonic. The index theorem supports the dimensional hierarchy of A-class topological insulator. Analogies to D-brane physics of string theory are discussed too.
Anomalous Quantum Hall Effect of 4D Graphene in Background Fields
L. B Drissi; H. Mhamdi; E. H Saidi
2011-09-05T23:59:59.000Z
Bori\\c{c}i-Creutz (\\emph{BC}) model describing the dynamics of light quarks in lattice \\emph{QCD} has been shown to be intimately linked to the four dimensional extension of 2D graphene refereed below to as four dimensional graphene (\\emph{4D-graphene}). Borrowing ideas from the field theory description of the usual \\emph{2D} graphene, we study in this paper the anomalous quantum Hall effect (AQHE) of the \\emph{BC} fermions in presence of a constant background field strength $\\mathcal{F}_{\\mu \
Wen, Xiao-Gang
The projective construction is a powerful approach to deriving the bulk and edge field theories of non-Abelian fractional quantum Hall (FQH) states and yields an understanding of non-Abelian FQH states in terms of the ...
Igor Romanovsky; Constantine Yannouleas; Uzi Landman
2009-01-15T23:59:59.000Z
We investigate the way that the degenerate manifold of midgap edge states in quasicircular graphene quantum dots with zig-zag boundaries supports, under free-magnetic-field conditions, strongly correlated many-body behavior analogous to the fractional quantum Hall effect (FQHE), familiar from the case of semiconductor heterostructures in high magnetic fields. Systematic exact-diagonalization (EXD) numerical studies are presented for the first time for 5 graphene REMs exhibit in all instances a single (0,N) polygonal-ring molecular (crystalline) structure, with all the electrons localized on the edge. Disruptions in the zig-zag boundary condition along the circular edge act effectively as impurities that pin the electron molecule, yielding single-particle densities with broken rotational symmetry that portray directly the azimuthal localization of the edge electrons.
Dynamics in the quantum Hall effect and the phase diagram of graphene
E. V. Gorbar; V. P. Gusynin; V. A. Miransky; I. A. Shovkovy
2008-08-28T23:59:59.000Z
The dynamics responsible for lifting the degeneracy of the Landau levels in the quantum Hall (QH) effect in graphene is studied by utilizing a low-energy effective model with a contact interaction. A detailed analysis of the solutions of the gap equation for Dirac quasiparticles is performed at both zero and nonzero temperatures. The characteristic feature of the solutions is that the order parameters connected with the QH ferromagnetism and magnetic catalysis scenarios necessarily coexist. The solutions reproduce correctly the experimentally observed novel QH plateaus in graphene in strong magnetic fields. The phase diagram of this system in the plane of temperature and electron chemical potential is analyzed. The phase transitions corresponding to the transitions between different QH plateaus in graphene are described.
M-Theory Brane as Giant Graviton and the Fractional Quantum Hall Effect
Ran Huo
2006-07-30T23:59:59.000Z
A small number of M-theory branes as giant gravitons in the M-theory sector of LLM geometry is studied as a probe. The abelian way shows that the low energy effective action for M-theory brane is exactly the 2d electron subject to a vertical magnetic field. We also briefly discuss the microscopic description of M2-brane giant graviton in this geometry, in the language of a combination of D0-branes as fuzzy 2-spheres. Then we go to the well-established Noncommutative Chern-Simons theory description. After quantization, well behaved Fractional Quantum Hall Effect is demonstrated. This goes beyond the original LLM description and should be some indication of novel geometry.
Quantum Hall Effect In Bilayer Systems And The Noncommutative Plane: A Toy Model Approach
B. Basu; Subir Ghosh
2005-07-19T23:59:59.000Z
We have presented a quantum mechanical toy model for the study of Coulomb interactions in Quantum Hall (QH) system. Inclusion of Coulomb interaction is essential for the study of {\\it{bilayer}} QH system and our model can simulate it, in the compound state, in a perturbative framework. We also show that in the noncommutative plane, the Coulomb interaction is modified at a higher order in the noncommutativity parameter $\\theta$, and only if $\\theta$ varies from layer to layer in the QH system.
Fractional Quantum Hall States in Graphene
Ahmed Jellal; Bellati Malika
2011-04-27T23:59:59.000Z
We quantum mechanically analyze the fractional quantum Hall effect in graphene. This will be done by building the corresponding states in terms of a potential governing the interactions and discussing other issues. More precisely, we consider a system of particles in the presence of an external magnetic field and take into account of a specific interaction that captures the basic features of the Laughlin series \
Engineering of Quantum Hall Effect from Type IIA String Theory on The K3 Surface
Adil Belhaj; Antonio Segui
2010-07-02T23:59:59.000Z
Using D-brane configurations on the K3 surface, we give six dimensional type IIA stringy realizations of the Quantum Hall Effect (QHE) in 1+2 dimensions. Based on the vertical and horizontal lines of the K3 Hodge diamond, we engineer two different stringy realizations. The vertical line presents a realization in terms of D2 and D6-branes wrapping the K3 surface. The horizontal one is associated with hierarchical stringy descriptions obtained from a quiver gauge theory living on a stack of D4-branes wrapping intersecting 2-spheres embedded in the K3 surface with deformed singularities. These geometries are classified by three kinds of the Kac-Moody algebras: ordinary, i.e finite dimensional, affine and indefinite. We find that no stringy QHE in 1+2 dimensions can occur in the quiver gauge theory living on intersecting 2-spheres arranged as affine Dynkin diagrams. Stringy realizations of QHE can be done only for the finite and indefinite geometries. In particular, the finite Lie algebras give models with fractional filling fractions, while the indefinite ones classify models with negative filling fractions which can be associated with the physics of holes in the graphene.
Weston, Ken
Coulomb interactions drive the existence of a correlated many-body state. Bilayer graphene represents distinct two-valued quantum numbers: layer index, electron spin, and the sublattice index of the graphene observation of fractional quantum Hall states in bilayer graphene. By placing bilayer graphene (blue in Fig. 1
Infrared Hall Effect in cuprates*
Fominov, Yakov
Diagram #12;Fermi surfaces H. KONTANI, K. KANKI, AND K. UEDA PRB 59 (1999). #12;IR Hall EffectB i m c = - 2 2 4 ( ) p H xy i = - =1000 cm-1 Schmadel, et al, PRB (2007) #12;Opt. Bi(2212): Far IR Hall H H i = - 84 cm-1 Schmadel, et al, PRB (2007) H ~ 0.3 cm-1/T H ~ aT1.65 #12
Viscosity of Quantum Hall Fluids J. E. Avron
Viscosity of Quantum Hall Fluids J. E. Avron Department of Physics, Technion, 32000 Haifa, Israel R April 25, 1997 Abstract The viscosity of quantum fluids with an energy gap at zero temperature is non of the parameter space). For a quantum Hall fluid on two dimensional tori this viscosity is computed. In this case
Kane, Charles
is varied, the degree of back- scattering between the two counterpropagating modes can be varied. For strong depletion under the gate, all backscattering can be effectively eliminated, and the source to drain con- ductance vanishes. In the opposite limit, the gate potential can be turned off, and the two-terminal source-to-drain
Topology-induced phase transitions in quantum spin Hall lattices
Bercioux, D.; Goldman, N.; Urban, D. F. [Freiburg Institute for Advanced Studies, Albert-Ludwigs-Universitaet, D-79104 Freiburg, Germany and Physikalisches Institut, Albert-Ludwigs-Universitaet, D-79104 Freiburg (Germany); Center for Nonlinear Phenomena and Complex Systems, UniversitAlbert-Ludwigs-Universitaet Libre de Bruxelles (U.L.B.), Code Postal 231, Campus Plaine, B-1050 Brussels (Belgium); Physikalisches Institut, Albert-Ludwigs-Universitaet, D-79104 Freiburg (Germany)
2011-02-15T23:59:59.000Z
Physical phenomena driven by topological properties, such as the quantum Hall effect, have the appealing feature that they are robust with respect to external perturbations. Lately, a new class of materials has emerged that manifests topological properties at room temperature and without the need of external magnetic fields. These topological insulators are band insulators with large spin-orbit interactions and exhibit the quantum spin-Hall (QSH) effect. Here we investigate the transition between QSH and normal insulating phases under topological deformations of a two-dimensional lattice. We demonstrate that the QSH phase present in the honeycomb lattice loses its robustness as the occupancy of extra lattice sites is allowed. Furthermore, we propose a method for verifying our predictions with fermionic cold atoms in optical lattices. In this context, the spin-orbit interaction is engineered via an appropriate synthetic gauge field.
Y-shape spin-separator for two-dimensional group-IV nanoribbons based on quantum spin hall effect
Gupta, Gaurav, E-mail: a0089293@nus.edu.sg; Abdul Jalil, Mansoor Bin; Liang, Gengchiau, E-mail: elelg@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Lin, Hsin [Graphene Research Centre and Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Bansil, Arun [Department of Physics, Northeastern University, Boston, Massachusetts 02115 (United States); Huang, Cheng-Yi; Tsai, Wei-Feng [Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China)
2014-01-20T23:59:59.000Z
An efficient spin-separator that operates in quantum spin hall phase has been investigated for two-dimensional group-IV materials. A three-terminal Y-shaped device has been simulated via non-equilibrium Green Function to demonstrate the separation of unpolarized current at source terminal into spin-polarized current of opposite polarity at the two drain terminals. Device controls, i.e., tunable buckling and perpendicular magnetic field have been modeled comprehensively to evaluate the device feasibility and performance. It is shown that these controls can preferentially steer current between the two drains to create a differential charge current with complementary spin polarization, thus enabling a convenient regulation of output signal.
S. Dhar; B. Basu; Subir Ghosh
2007-06-27T23:59:59.000Z
We explain the intrinsic spin Hall effect from generic anyon dynamics in the presence of external electromagnetic field. The free anyon is represented as a spinning particle with an underlying non-commutative configuration space. The Berry curvature plays a major role in the analysis.
Contactless measurement of alternating current conductance in quantum Hall structures
Drichko, I. L.; Diakonov, A. M.; Malysh, V. A.; Smirnov, I. Yu.; Ilyinskaya, N. D.; Usikova, A. A. [A. F. Ioffe Physical-Technical Institute of the Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Galperin, Y. M. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo (Norway); A. F. Ioffe Physical-Technical Institute of the Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Kummer, M.; Känel, H. von [Laboratorium für Festkörperphysik ETH Zürich, CH-8093 Zürich (Switzerland)
2014-10-21T23:59:59.000Z
We report a procedure to determine the frequency-dependent conductance of quantum Hall structures in a broad frequency domain. The procedure is based on the combination of two known probeless methods—acoustic spectroscopy and microwave spectroscopy. By using the acoustic spectroscopy, we study the low-frequency attenuation and phase shift of a surface acoustic wave in a piezoelectric crystal in the vicinity of the electron (hole) layer. The electronic contribution is resolved using its dependence on a transverse magnetic field. At high frequencies, we study the attenuation of an electromagnetic wave in a coplanar waveguide. To quantitatively calibrate these data, we use the fact that in the quantum-Hall-effect regime the conductance at the maxima of its magnetic field dependence is determined by extended states. Therefore, it should be frequency independent in a broad frequency domain. The procedure is verified by studies of a well-characterized p-SiGe/Ge/SiGe heterostructure.
Josephson inplane and tunneling currents in bilayer quantum Hall system
Ezawa, Z. F. [Nishina Center, RIKEN, Saitama 351-0198 (Japan); Tsitsishvili, G. [Georgia Department of Physics, Tbilisi State University, Tbilisi 0179 (Georgia); Sawada, A. [Research Center for Low Temperature and Materials Sciences, Kyoto University, Kyoto 606-8501 (Japan)
2013-12-04T23:59:59.000Z
A Bose-Einstein condensation is formed by composite bosons in the quantum Hall state. A composite boson carries the fundamental charge (–e). We investigate Josephson tunneling of such charges in the bilayer quantum Hall system at the total filling ? = 1. We show the existence of the critical current for the tunneling current to be coherent and dissipationless in tunneling experiments with various geometries.
Constantine Yannouleas; Igor Romanovsky; Uzi Landman
2010-09-13T23:59:59.000Z
Many-body calculations of the total energy of interacting Dirac electrons in finite graphene samples exhibit joint occurrence of cusps at angular momenta corresponding to fractional fillings characteristic of formation of incompressible (gapped) correlated states (nu=1/3 in particular) and opening of an insulating energy gap (that increases with the magnetic field) at the Dirac point, in correspondence with experiments. Single-particle basis functions obeying the zigzag boundary condition at the sample edge are employed in exact diagonalization of the interelectron Coulomb interaction, showing, at all sizes, mixed equal-weight bulk and edge components. The consequent depletion of the bulk electron density attenuates the fractional-quantum-Hall-effect excitation energies and the edge charge accumulation results in a gap in the many-body spectrum.
Topological order in the fractional quantum Hall states
Barkeshli, Maissam
2010-01-01T23:59:59.000Z
This thesis is focused on the theoretical characterization of topological order in non-Abelian fractional quantum Hall (FQH) states. The first part of the thesis is concerned with the ideal wave function approach to FQH ...
Wei Chen; Z. D. Wang; R. Shen; D. Y. Xing
2014-05-21T23:59:59.000Z
We propose an entanglement detector composed of two quantum spin Hall insulators and a side gate deposited on one of the edge channels. For an ac gate voltage, the differential noise contributed from the entangled electron pairs exhibits the nontrivial step structures, from which the spin entanglement concurrence can be easily obtained. The possible spin dephasing effects in the quantum spin Hall insulators are also included.
The fluctuation induced Hall effect
Shen, W.; Prager, S.C.
1993-02-01T23:59:59.000Z
The fluctuation induced Hall term, [le][approximately][ovr J] [times] [approximately][ovr B][ge], has been measured in the MST reversed field pinch. The term is of interest as a possible source of current self-generation (dynamo). It is found to be non-negligible, but small in that it can account for less than 25% of the dynamo driven current.
The fluctuation induced Hall effect
Shen, W.; Prager, S.C.
1993-02-01T23:59:59.000Z
The fluctuation induced Hall term, {le}{approximately}{ovr J} {times} {approximately}{ovr B}{ge}, has been measured in the MST reversed field pinch. The term is of interest as a possible source of current self-generation (dynamo). It is found to be non-negligible, but small in that it can account for less than 25% of the dynamo driven current.
Magnetic Catalysis and Quantum Hall Ferromagnetism in Weakly Coupled Graphene
Gordon W. Semenoff; Fei Zhou
2011-04-25T23:59:59.000Z
We study the realization in a model of graphene of the phenomenon whereby the tendency of gauge-field mediated interactions to break chiral symmetry spontaneously is greatly enhanced in an external magnetic field. We prove that, in the weak coupling limit, and where the electron-electron interaction satisfies certain mild conditions, the ground state of charge neutral graphene in an external magnetic field is a quantum Hall ferromagnet which spontaneously breaks the emergent U(4) symmetry to U(2)XU(2). We argue that, due to a residual CP symmetry, the quantum Hall ferromagnet order parameter is given exactly by the leading order in perturbation theory. On the other hand, the chiral condensate which is the order parameter for chiral symmetry breaking generically obtains contributions at all orders. We compute the leading correction to the chiral condensate. We argue that the ensuing fermion spectrum resembles that of massive fermions with a vanishing U(4)-valued chemical potential. We discuss the realization of parity and charge conjugation symmetries and argue that, in the context of our model, the charge neutral quantum Hall state in graphene is a bulk insulator, with vanishing longitudinal conductivity due to a charge gap and Hall conductivity vanishing due to a residual discrete particle-hole symmetry.
Hall effect in incompressible magnetic reconnection
Dasso, Sergio
. GoÂ´mez Instituto de AstronomiÂ´a y FiÂ´sica del Espacio (IAFE), Departamento de FiÂ´sica, Facultad de region. Citation: Morales, L. F., S. Dasso, and D. O. GoÂ´mez (2005), Hall effect in incompressible
Theory of the Anomalous Hall Effect in the Insulating Regime
Liu, Xiongjun
2012-10-19T23:59:59.000Z
The Hall resistivity in ferromagnetic materials has an anomalous contribution proportional to the magnetization, which is defined as the anomalous Hall effect (AHE). Being a central topic in the study of ferromagnetic materials for many decades...
Geometric Spin Hall Effect of Light
Andrea Aiello; Christoph Marquardt; Gerd Leuchs
2009-02-26T23:59:59.000Z
We describe a novel phenomenon occurring when a polarized Gaussian beam of light is observed in a Cartesian reference frame whose axes are not parallel to the direction of propagation of the beam. Such phenomenon amounts to an intriguing spin-dependent shift of the position of the center of the beam, with manners akin to the spin Hall effect of light. We demonstrate that this effect is unavoidable when the light beam possesses a nonzero transverse angular momentum.
Negative nonlocal resistance in mesoscopic gold Hall bars : absence of giant spin Hall effect.
Mihajlovic, G.; Pearson, J. E.; Garcia, M. A.; Bader, S. D.; Hoffmann, A.; Univ. Complutense de Madrid
2009-01-01T23:59:59.000Z
We report the observation of negative nonlocal resistances in multiterminal mesoscopic gold Hall bar structures whose characteristic dimensions are larger than the electron mean-free path. Our results can only be partially explained by a classical diffusive model of the nonlocal transport, and are not consistent with a recently proposed model based on spin Hall effects. Instead, our analysis suggests that a quasiballistic transport mechanism is responsible for the observed negative nonlocal resistance. Based on the sensitivity of our measurements and the spin Hall effect model, we find an upper limit for the spin Hall angle in gold of 0.023 at 4.5 K.
Crystalline phases of graphene quantum Hall polariton fluids
Francesco M. D. Pellegrino; Vittorio Giovannetti; Allan H. MacDonald; Marco Polini
2015-05-26T23:59:59.000Z
There is growing experimental interest in coupling cavity photons to the cyclotron resonance excitations of electron liquids in high-mobility semiconductor quantum wells or graphene sheets. These media offer unique platforms to carry out fundamental studies of exciton-polariton condensation and cavity quantum electrodynamics in a regime in which electron-electron (e-e) interactions are expected to play a pivotal role. Focusing on graphene, we present a theoretical study of the impact of e-e interactions on a quantum Hall polariton fluid (QHPF), i.e. a fluid of magneto-excitons resonantly coupled to cavity photons. We show that e-e interactions are responsible for an instability of graphene integer QHPFs towards a crystalline phase. We demonstrate that this phase can be detected by measuring the collective excitation spectra, which soften at a characteristic wave vector of the order of the inverse magnetic length.
Controllable spin entanglement production in a quantum spin Hall ring
Anders Ström; Henrik Johannesson; Patrik Recher
2015-03-13T23:59:59.000Z
We study the entanglement production in a quantum spin Hall ring geometry where electrons of opposite spins are emitted in pairs from a source and collected in two different detectors. Postselection of coincidence detector events gives rise to entanglement in the system, measurable through correlations between the outcomes in the detectors. We have chosen a geometry such that the entanglement depends on the dynamical phases picked up by the edge states as they move around the ring. In turn, the dependence of the phases on gate potential and Rashba interaction allows for a precise electrical control of the entanglement production in the ring.
Renormalization group approach to energy level statistics at the integer quantum Hall transition
Chemnitz, Technische Universität
Renormalization group approach to energy level statistics at the integer quantum Hall transition) approach to study the energy level statistics at the integer quantum Hall (QH) transition. Within the RG, at the transition, the nearest neighbor energy level spacing distribution (LSD) exhibits well-pronounced level
Temperature dependence of conductance fluctuations in quantum Hall multilayers H. A. Walling,1
Xu, Jing
)]. This surface phase dominates vertical transport at low temperatures that freeze out parallel bulk transport.2 fluctuations in low-temperature, vertical transport through quantum Hall multilayers. The mesas studied dependence of reproduc- ible conductance fluctuations in quantum Hall multilayers. The vertical transport
Higgs Mechanism and Anomalous Hall Effect in Three-Dimensional Topological Superconductors
Nogueira, Flavio S; Eremin, Ilya
2015-01-01T23:59:59.000Z
We demonstrate that the Higgs mechanism in three-dimensional topological superconductors exhibits unique features with experimentally observable consequences. The Higgs model we discuss has two superconducting components and an axion-like magnetoelectric term with the phase difference of the superconducting order parameters playing the role of the axion field. Due to this additional term, quantum electromagnetic and phase fluctuations lead to a robust topologically non-trivial state that cannot be continuously deformed into a topologically non-trivial one. In the low frequency London regime an anomalous Hall effect is induced in the presence of an applied electric field parallel to the surface. This anomalous Hall current is induced by a Lorentz-like force arising from the axion term, and it involves the relative superfluid velocity of the superconducting components. The anomalous Hall current has a negative sign, a situation reminiscent, but quite distinct in physical origin, of the anomalous Hall effect obs...
Photonic spin Hall effect in topological insulators
Zhou, Xinxing; Ling, Xiaohui; Chen, Shizhen; Luo, Hailu; Wen, Shuangchun
2013-01-01T23:59:59.000Z
In this paper we theoretically investigate the photonic spin Hall effect (SHE) of a Gaussian beam reflected from the interface between air and topological insulators (TIs). The photonic SHE is attributed to spin-orbit coupling and manifests itself as in-plane and transverse spin-dependent splitting. We reveal that the spin-orbit coupling effect in TIs can be routed by adjusting the axion angle variations. Unlike the transverse spin-dependent splitting, we find that the in-plane one is sensitive to the axion angle. It is shown that the polarization structure in magneto-optical Kerr effect is significantly altered due to the spin-dependent splitting in photonic SHE. We theoretically propose a weak measurement method to determine the strength of axion coupling by probing the in-plane splitting of photonic SHE.
Hall effect at a tunable metal-insulator transition
Teizer, Winfried; Hellman, F.; Dynes, RC.
2003-01-01T23:59:59.000Z
Using a rotating magnetic field, the Hall effect in three-dimensional amorphous GdxSi1-x has been measured in the critical regime of the metal-insulator transition for a constant total magnetic field. The Hall coefficient R-0 is negative, indicating...
Electrically tunable quantum spin Hall state in topological crystalline insulator thin films
Liu, Junwei
Based on electronic structure calculations and theoretical analysis, we predict the (111) thin films of the SnTe class of three-dimensional (3D) topological crystalline insulators (TCIs) realize the quantum spin Hall phase ...
Nikolic, Branislav K.
Mesoscopic spin Hall effect in multiprobe ballistic spin-orbit-coupled semiconductor bridges attached to ballistic quantum-coherent two-dimensional electron gas 2DEG in semiconductor heterostructure current are signatures of the spin Hall effect in four-probe Rashba spin-split semiconductor
M5-brane defect and quantum Hall effect in AdS{sub 4}xN(1,1)/N=3 superconformal field theory
Fujita, Mitsutoshi [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)
2011-05-15T23:59:59.000Z
We study the d=11 gravity dual AdS{sub 4}xN(1,1) of the d=3 N=3 flavored Chern-Simons-matter theory. In the dual gravity side, we analyze the M5-brane filling AdS{sub 3} inside AdS{sub 4} and derive the quantized Hall conductivity of the dual gauge theory. In the gauge theory side, this M5-brane intersects the gauge theory at the codimension-one defect.
Experimental Observation of the Inverse Spin Hall Effect at Room Temperature
Liu, Baoli; Shi, Junren; Wang, Wenxin; Zhao, Hongming; Li, Dafang; /Beijing, Inst. Phys.; Zhang, Shoucheng; /Stanford U., Phys. Dept.; Xue, Qikun; Chen, Dongmin; /Beijing, Inst. Phys.
2010-03-16T23:59:59.000Z
We observe the inverse spin Hall effect in a two-dimensional electron gas confined in Al-GaAs/InGaAs quantum wells. Specifically, they find that an inhomogeneous spin density induced by the optical injection gives rise to an electric current transverse to both the spin polarization and its gradient. The spin Hall conductivity can be inferred from such a measurement through the Einstein relation and the onsager relation, and is found to have the order of magnitude of 0.5(e{sup 2}/h). The observation is made at the room temperature and in samples with macroscopic sizes, suggesting that the inverse spin Hall effects is a robust macroscopic transport phenomenon.
Topological solitons in the noncommutative plane and quantum Hall Skyrmions
Ezawa, Z.F. [Department of Physics, Tohoku University, Sendai, 980-8578 (Japan); Tsitsishvili, G. [Department of Physics, Tohoku University, Sendai, 980-8578 (Japan); Department of Theoretical Physics, A. Razmadze Mathematical Institute, Tbilisi, 380093 (Georgia)
2005-10-15T23:59:59.000Z
We analyze topological solitons in the noncommutative plane by taking a concrete instance of the quantum Hall system with the SU(N) symmetry, where a soliton is identified with a Skyrmion. It is shown that a topological soliton induces an excitation of the electron number density from the ground-state value around it. When a judicious choice of the topological charge density J{sub 0}(x) is made, it acquires a physical reality as the electron density excitation {delta}{rho}{sup cl}(x) around a topological soliton, {delta}{rho}{sup cl}(x)=-J{sub 0}(x). Hence a noncommutative soliton carries necessarily the electric charge proportional to its topological charge. A field-theoretical state is constructed for a soliton state irrespectively of the Hamiltonian. In general, it involves an infinitely many parameters. They are fixed by minimizing its energy once the Hamiltonian is chosen. We study explicitly the cases where the system is governed by the hard-core interaction and by the noncommutative CP{sup N-1} model, where all these parameters are determined analytically and the soliton excitation energy is obtained.
Geller, Michael R.
N = z1 z2 Â¯ zN 2 of charge-1 fermion fields :ei 2 : M, where is a u 1 boson15 and M a neutral Majorana anyon braiding for fault-tolerant quantum computation.20 Unfortunately, the braiding matrices gener
Optical detection of spin Hall effect in metals
Erve, O. M. J. van ‘t, E-mail: Olaf.Vanterve@nrl.navy.mil; Hanbicki, A. T.; McCreary, K. M.; Li, C. H.; Jonker, B. T. [Materials Science and Technology Division, Naval Research Laboratory, Washington, DC 20375 (United States)
2014-04-28T23:59:59.000Z
Optical techniques have been widely used to probe the spin Hall effect in semiconductors. In metals, however, only electrical methods such as nonlocal spin valve transport, ferromagnetic resonance, or spin torque transfer experiments have been successful. These methods require complex processing techniques and measuring setups. We show here that the spin Hall effect can be observed in non-magnetic metals such as Pt and ?-W, using a standard bench top magneto-optical Kerr system with very little sample preparation. Applying a square wave current and using Fourier analysis significantly improve our detection level. One can readily determine the angular dependence of the induced polarization on the bias current direction (very difficult to do with voltage detection), the orientation of the spin Hall induced polarization, and the sign of the spin Hall angle. This optical approach is free from the complications of various resistive effects, which can compromise voltage measurements. This opens up the study of spin Hall effect in metals to a variety of spin dynamic and spatial imaging experiments.
Color Glass Condensates in dense quark matter and quantum Hall states of gluons
Aiichi Iwazaki
2006-04-26T23:59:59.000Z
We apply the effective theory of color glass condensate to the analysis of gluon states in dense quark matter, in which the saturation region of gluons is also present. We find that in the region two point function of gluons shows algebraic long range order. The order is completely the same as the one gluons show in the dense quark matter, which form quantum Hall states. The order leads to the vanishing of massless gluon pole. We also find that the saturation region of gluons extends from small $x$ to even large $x\\lesssim 1$ in much dense quark matter. We point out a universality that the color glass condensate is a property of hadrons at high energy and of quark matter at high baryon density.
Electric control of the spin Hall effect by intervalley transitions
Okamoto, N.; Kurebayashi, H.; Trypiniotis, T.; Farrer, I.; Ritchie, D. A.; Saitoh, E.; Sinova, J.; Mašek, J.; Jungwirth, T.; Barnes, C. H. W.
2014-08-10T23:59:59.000Z
tunability of the creation/detection efficiency of spin currents, with clear relevance for future memory and logic devices. 8 I. METHODS A. Measurement The sample structure used in this study is Si-doped (the initial electron density n0e=1.01×1016 cm?3) n... ., & Jungwirth T. Spin-injection Hall effect in a planar photovoltaic cell Nature Phys. 5, 675 (2009). 24 Wunderlich, J., Park, B. G., Irvine, A. C., Zarbo, L. P. , Rozkotova, E., Nemec, P., Novak, V., Sinova, J., & Jungwirth, T. Spin Hall effect transistor...
Coulomb Oscillations in Antidots in the Integer and Fractional Quantum Hall Regimes
A. Kou; C. M. Marcus; L. N. Pfeiffer; K. W. West
2012-01-08T23:59:59.000Z
We report measurements of resistance oscillations in micron-scale antidots in both the integer and fractional quantum Hall regimes. In the integer regime, we conclude that oscillations are of the Coulomb type from the scaling of magnetic field period with the number of edges bound to the antidot. Based on both gate-voltage and field periods, we find at filling factor {\
Iye, Yasuhiro
Resistance Fluctuations and AharonovBohm-Type Oscillations in Antidot Arrays in the Quantum Hall fluctuations (RFs) and the other is the AharonovBohm (AB)-type oscillations. Their dependences on the magnetic field and the gate voltage are quite distinct. While the aperiodic RFs are attributed to the complex
Coulomb Oscillations in Antidots in the Integer and Fractional Quantum Hall Regimes
Kou, A; Pfeiffer, L N; West, K W
2012-01-01T23:59:59.000Z
We report measurements of resistance oscillations in micron-scale antidots in both the integer and fractional quantum Hall regimes. In the integer regime, we conclude that oscillations are of the Coulomb type from the scaling of magnetic field period with the number of edges bound to the antidot. Based on both gate-voltage and field periods, we find at filling factor {\
"Impact of heavy adatom segregation on the quantum spin Hall phase in graphene"
Escolano, Francisco
"Impact of heavy adatom segregation on the quantum spin Hall phase in graphene" Impartit per: David physics is to realize a topological insulating phase in 2-dimensional Graphene [1,2]. Recent theoretical studies have shown that dissipation-less edge conducting channels emerge in graphene nanoribbons when
"Impact of heavy adatom segregation on the quantum spin Hall phase in graphene"
Escolano, Francisco
"Impact of heavy adatom segregation on the quantum spin Hall phase in graphene" Impartido por physics is to realize a topological insulating phase in 2-dimensional Graphene [1,2]. Recent theoretical studies have shown that dissipation-less edge conducting channels emerge in graphene nanoribbons when
"Impact of heavy adatom segregation on the quantum spin Hall phase in graphene"
Escolano, Francisco
"Impact of heavy adatom segregation on the quantum spin Hall phase in graphene" By: David Soriano is to realize a topological insulating phase in 2-dimensional Graphene [1,2]. Recent theoretical studies have shown that dissipation-less edge conducting channels emerge in graphene nanoribbons when doped with soft
Quantum Hall phases and plasma analogy in rotating trapped Bose gases
. In this regime, the atoms all condense in the same one-particle state and the gas forms a Bose. Our analysis is based on the interpretation of the densities of quantum Hall trial states as Gibbs-Einstein condensate (BEC). Th
Confinement-deconfinement transition due to spontaneous symmetry breaking in quantum Hall bilayers
Pikulin, D I; Hyart, T
2015-01-01T23:59:59.000Z
Band-inverted electron-hole bilayers support quantum spin Hall insulator and exciton condensate phases [1-4]. We investigate such a bilayer in an external magnetic field. We show that the interlayer correlations lead to a formation of a helical quantum Hall exciton condensate state. In contrast to the chiral edge states of the quantum Hall exciton condensate in electron-electron bilayers [5-7], existence of the electron and hole counterpropagating edge modes result in formation of a ground state spin-texture not supporting gapless single-particle excitations. This feature has deep consequences for the low energy behavior of the system. Namely, the charged edge excitations in a sufficiently narrow Hall bar are confined i.e. a charge on one of the edges always gives rise to an opposite charge on the other edge. Moreover, we show that a magnetic field and gate voltages allow to control a confinement-deconfinement transition of charged edge excitations, which can be probed with nonlocal conductance. Confinement-d...
Niu, Qian
numbers: 72.10.Bg, 72.20.Dp, 73.63.Hs The generation of an electric current in the transverse direction, other variants, such as the thermal Hall effect[3], can manifest when the longitudi- nal electric field of an electric field is known as a Hall effect. The transverse force is usually provided by the Lorentz force
Effects of Enhanced Eathode Electron Emission on Hall Thruster Operation
Y. Raitses, A. Smirnov and N. J. Fisch
2009-04-24T23:59:59.000Z
Interesting discharge phenomena are observed that have to do with the interaction between the magnetized Hall thruster plasma and the neutralizing cathode. The steadystate parameters of a highly ionized thruster discharge are strongly influenced by the electron supply from the cathode. The enhancement of the cathode electron emission above its self-sustained level affects the discharge current and leads to a dramatic reduction of the plasma divergence and a suppression of large amplitude, low frequency discharge current oscillations usually related to an ionization instability. These effects correlate strongly with the reduction of the voltage drop in the region with the fringing magnetic field between the thruster channel and the cathode. The measured changes of the plasma properties suggest that the electron emission affects the electron cross-field transport in the thruster discharge. These trends are generalized for Hall thrusters of various configurations.
Magnetic Field Evolution in Neutron Star Crusts due to the Hall Effect and Ohmic Decay
Andrew Cumming; Phil Arras; Ellen G. Zweibel
2004-02-17T23:59:59.000Z
We present calculations of magnetic field evolution by the Hall effect and Ohmic decay in neutron star crusts. We first discuss when and for which neutron stars the Hall effect is important relative to Ohmic decay. We compute the evolution of an initial field distribution by Ohmic decay, and give approximate analytic formulas for both the surface and interior fields as a function of time. We then discuss the subsequent evolution by the Hall effect, giving several examples which illustrate how the field configuration evolves. Hall wave eigenfunctions are computed, including the effect of the large density change across the crust. We estimate the response of the crust to the magnetic stresses induced by Hall waves, and give a detailed discussion of the boundary conditions at the solid-liquid interface. Finally, we discuss the implications for the Hall cascade proposed by Goldreich & Reisenegger.
Observation of Chiral Heat Transport in the Quantum Hall Regime G. Granger,1
Eisenstein, Jim
91125, USA 2 Sandia National Laboratories, Albuquerque, New Mexico 87185, USA (Received 17 October 2008 are based on the thermoelectric effect. In the ¼ 1 integer quantized Hall state, a thermoelectric signal, the thermoelectric signal is reduced, showing that the electrons cool as they propagate along the edge. DOI: 10
Kühne, P., E-mail: kuehne@huskers.unl.edu; Schubert, M., E-mail: schubert@engr.unl.edu; Hofmann, T., E-mail: thofmann@engr.unl.edu [Department of Electrical Engineering and Center for Nanohybrid Functional Materials, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States); Herzinger, C. M., E-mail: cherzinger@jawoollam.com; Woollam, J. A., E-mail: jwoollam@jawoollam.com [J. A. Woollam Co., Inc., 645 M Street, Suite 102, Lincoln, Nebraska 68508-2243 (United States)
2014-07-15T23:59:59.000Z
We report on the development of the first integrated mid-infrared, far-infrared, and terahertz optical Hall effect instrument, covering an ultra wide spectral range from 3 cm{sup ?1} to 7000 cm{sup ?1} (0.1–210 THz or 0.4–870 meV). The instrument comprises four sub-systems, where the magneto-cryostat-transfer sub-system enables the usage of the magneto-cryostat sub-system with the mid-infrared ellipsometer sub-system, and the far-infrared/terahertz ellipsometer sub-system. Both ellipsometer sub-systems can be used as variable angle-of-incidence spectroscopic ellipsometers in reflection or transmission mode, and are equipped with multiple light sources and detectors. The ellipsometer sub-systems are operated in polarizer-sample-rotating-analyzer configuration granting access to the upper left 3 × 3 block of the normalized 4 × 4 Mueller matrix. The closed cycle magneto-cryostat sub-system provides sample temperatures between room temperature and 1.4 K and magnetic fields up to 8 T, enabling the detection of transverse and longitudinal magnetic field-induced birefringence. We discuss theoretical background and practical realization of the integrated mid-infrared, far-infrared, and terahertz optical Hall effect instrument, as well as acquisition of optical Hall effect data and the corresponding model analysis procedures. Exemplarily, epitaxial graphene grown on 6H-SiC, a tellurium doped bulk GaAs sample and an AlGaN/GaN high electron mobility transistor structure are investigated. The selected experimental datasets display the full spectral, magnetic field and temperature range of the instrument and demonstrate data analysis strategies. Effects from free charge carriers in two dimensional confinement and in a volume material, as well as quantum mechanical effects (inter-Landau-level transitions) are observed and discussed exemplarily.
Krypton charge exchange cross sections for Hall effect thruster models
Hause, Michael L. [Institute for Scientific Research, Boston College, Chestnut Hill, Massachusetts 02159 (United States); Prince, Benjamin D.; Bemish, Raymond J. [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, New Mexico 87117 (United States)
2013-04-28T23:59:59.000Z
Following discharge from a Hall effect thruster, charge exchange occurs between ions and un-ionized propellant atoms. The low-energy cations produced can disturb operation of onboard instrumentation or the thruster itself. Charge-exchange cross sections for both singly and doubly charged propellant atoms are required to model these interactions. While xenon is the most common propellant currently used in Hall effect thrusters, other propellants are being considered, in particular, krypton. We present here guided-ion beam measurements and comparisons to semiclassical calculations for Kr{sup +} + Kr and Kr{sup 2+} + Kr cross sections. The measurements of symmetric Kr{sup +} + Kr charge exchange are in good agreement with both the calculations including spin-orbit effects and previous measurements. For the symmetric Kr{sup 2+} + Kr reaction, we present cross section measurements for center-of-mass energies between 1 eV and 300 eV, which spans energies not previously examined experimentally. These cross section measurements compare well with a simple one-electron transfer model. Finally, cross sections for the asymmetric Kr{sup 2+} + Kr {yields} Kr{sup +} + Kr{sup +} reaction show an onset near 12 eV, reaching cross sections near constant value of 1.6 A{sup 2} with an exception near 70-80 eV.
Towards Managing Variability in the Safety Design of an Automotive Hall Effect Sensor
Paris-Sud XI, Université de
Towards Managing Variability in the Safety Design of an Automotive Hall Effect Sensor Dimitri Van) as the main devel- opment process for an automotive Hall Effect sensor. This versatile component is integrated for every automotive application in which the sensor is to be used. In addition, no support is given
Fully-kinetic PIC simulations for Hall-effect thrusters
Fox, Justin M., 1981-
2007-01-01T23:59:59.000Z
In recent years, many groups have numerically modeled the near-anode region of a Hall thruster in attempts to better understand the associated physics of thruster operation. Originally, simulations assumed a continuum ...
Multi-DOF precision positioning methodology using two-axis Hall-effect sensors
Kawato, Yusuke
2006-08-16T23:59:59.000Z
A novel sensing methodology using two-axis Hall-effect sensors is proposed, where the absolute positioning of a device atop any magnet matrix is possible. This methodology has the capability of micrometer-order positioning resolution as well...
Gauge Potential Formulations of the Spin Hall Effect in Graphene
O. F. Dayi; E. Yunt
2011-05-27T23:59:59.000Z
Two different gauge potential methods are engaged to calculate explicitly the spin Hall conductivity in graphene. The graphene Hamiltonian with spin-orbit interaction is expressed in terms of kinematic momenta by introducing a gauge potential. A formulation of the spin Hall conductivity is established by requiring that the time evolution of this kinematic momentum vector vanishes. We then calculated the conductivity employing the Berry gauge fields. We show that both of the gauge fields can be deduced from the pure gauge field arising from the Foldy-Wouthuysen transformations.
Electroweak Hall Effect of Neutrino and Coronal Heating
Ishikawa, Kenzo
2015-01-01T23:59:59.000Z
The inversion of temperature at the solar corona is hard to understand from classical physics, and the coronal heating mechanism remains unclear. The heating in the quiet region seems contradicting with the thermodynamics and is a keen problem for physicists. A new mechanism for the coronal heating based on the neutrino radiative transition unique in the corona region is studied. The probability is enormously amplified by an electroweak Chern-Simons form and overlapping waves, and the sufficient energy is transfered. Thus the coronal heating is understood from the quantum effects of the solar neutrino.
Electroweak Hall Effect of Neutrino and Coronal Heating
Kenzo Ishikawa; Yutaka Tobita
2015-03-25T23:59:59.000Z
The inversion of temperature at the solar corona is hard to understand from classical physics, and the coronal heating mechanism remains unclear. The heating in the quiet region seems contradicting with the thermodynamics and is a keen problem for physicists. A new mechanism for the coronal heating based on the neutrino radiative transition unique in the corona region is studied. The probability is enormously amplified by an electroweak Chern-Simons form and overlapping waves, and the sufficient energy is transfered. Thus the coronal heating is understood from the quantum effects of the solar neutrino.
Visualizing edge states with an atomic Bose gas in the quantum Hall regime
Stuhl, B K; Aycock, L M; Genkina, D; Spielman, I B
2015-01-01T23:59:59.000Z
We engineered a two-dimensional magnetic lattice in an elongated strip geometry, with effective per-plaquette flux ~4/3 times the flux quanta. We imaged the localized edge and bulk states of atomic Bose-Einstein condensates in this strip, with single lattice-site resolution along the narrow direction. Further, we observed both the skipping orbits of excited atoms traveling down our system's edges, analogues to edge magnetoplasmons in 2-D electron systems, and a dynamical Hall effect for bulk excitations. Our lattice's long direction consisted of the sites of an optical lattice and its narrow direction consisted of the internal atomic spin states. Our technique has minimal heating, a feature that will be important for spectroscopic measurements of the Hofstadter butterfly and realizations of Laughlin's charge pump.
Visualizing edge states with an atomic Bose gas in the quantum Hall regime
B. K. Stuhl; H. -I Lu; L. M. Aycock; D. Genkina; I. B. Spielman
2015-02-09T23:59:59.000Z
We engineered a two-dimensional magnetic lattice in an elongated strip geometry, with effective per-plaquette flux ~4/3 times the flux quanta. We imaged the localized edge and bulk states of atomic Bose-Einstein condensates in this strip, with single lattice-site resolution along the narrow direction. Further, we observed both the skipping orbits of excited atoms traveling down our system's edges, analogues to edge magnetoplasmons in 2-D electron systems, and a dynamical Hall effect for bulk excitations. Our lattice's long direction consisted of the sites of an optical lattice and its narrow direction consisted of the internal atomic spin states. Our technique has minimal heating, a feature that will be important for spectroscopic measurements of the Hofstadter butterfly and realizations of Laughlin's charge pump.
Genomic instability and bystander effects induced by high-LET radiation Eric J Hall*,1
of the radiobiological effects of high- linear energy transfer (LET) radiation is essential for radiation protectionGenomic instability and bystander effects induced by high-LET radiation Eric J Hall*,1 and Tom K, it has always been accepted that the deleterious effects of ionizing radiation, such as mutation
The Effect of Magnetic Field on the Performance of Low-Power Cylindrical Hall Thrusters
The Effect of Magnetic Field on the Performance of Low-Power Cylindrical Hall Thrusters IEPC-2005-099 Presented at the 29th International Electric Propulsion Conference, Princeton University, October 31 for scaling down. The effect of the magnetic field on the discharge characteristics and efficiency of the low
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Kozuka, Y.; Tsukazaki, A.; Maryenko, D.; Falson, J.; Bell, C.; Kim, M.; Hikita, Y.; Hwang, H. Y.; Kawasaki, M.
2012-02-01T23:59:59.000Z
We investigate the spin susceptibility (g*m*) of dilute two-dimensional (2D) electrons confined at the MgxZn1-xO/ZnO heterointerface. Magnetotransport measurements show a four-fold enhancement of g*m*, dominated by the increase in the Landé g-factor. The g-factor enhancement leads to a ferromagnetic instability of the electron gas as evidenced by sharp resistance spikes. At high magnetic field, the large g*m* leads to full spin polarization, where we found sudden increase in resistance around the filling factors of half-integer, accompanied by complete disappearance of fractional quantum Hall (QH) states. Along with its large effective mass and the high electron mobility, our result indicates that the ZnO 2D system is ideal for investigating the effect of electron correlations in the QH regime.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Kozuka, Y.; Tsukazaki, A.; Maryenko, D.; Falson, J.; Bell, C.; Kim, M.; Hikita, Y.; Hwang, H. Y.; Kawasaki, M.
2012-02-01T23:59:59.000Z
We investigate the spin susceptibility (g*m*) of dilute two-dimensional (2D) electrons confined at the MgxZn1-xO/ZnO heterointerface. Magnetotransport measurements show a four-fold enhancement of g*m*, dominated by the increase in the Landé g-factor. The g-factor enhancement leads to a ferromagnetic instability of the electron gas as evidenced by sharp resistance spikes. At high magnetic field, the large g*m* leads to full spin polarization, where we found sudden increase in resistance around the filling factors of half-integer, accompanied by complete disappearance of fractional quantum Hall (QH) states. Along with its large effective mass and the high electron mobility, our result indicates thatmore »the ZnO 2D system is ideal for investigating the effect of electron correlations in the QH regime.« less
Effective anomalous Hall coefficient in an ultrathin Co layer sandwiched by Pt layers
Zhang, Peng; Wu, Di; Jiang, Zhengsheng; Sang, Hai, E-mail: weiwei.lin@u-psud.fr, E-mail: haisang@nju.edu.cn [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Lin, Weiwei, E-mail: weiwei.lin@u-psud.fr, E-mail: haisang@nju.edu.cn [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Institut d'Electronique Fondamentale, Université Paris-Sud, Orsay 91405 (France)
2014-02-14T23:59:59.000Z
Anomalous Hall effect in Co/Pt multilayer is important to study the effect of interface with strong spin-orbit coupling. However, the shunting effect of the layers in such system and the circuit in the plane perpendicular to the injected current were overlooked in most works and thus, anomalous Hall coefficient in Co/Pt multilayer has not been determined accurately. Considering the shunting effect and the equivalent circuit, we show that the effective anomalous Hall coefficient of a 0.5?nm thick Co layer sandwiched by Pt layers R{sub S} is 0.29?±?0.01????cm/T at the zero temperature limit and increases to about 0.73????cm/T at the temperature of 300?K. R{sub S} is one order larger than that in bulk Co film, indicating the large contribution of the Co/Pt interface. R{sub S} increases with the resistivity of Co as well as a resistivity independent contribution of ?0.23?±?0.01????cm/T. The equivalent anomalous Hall current in the Co layer has a maximum of 1.1% of the injected transverse current in the Co layer around the temperature of 80?K.
Radial scale effect on the performance of low-power cylindrical Hall plasma thrusters
Seo, Mihui; Lee, Jongsub; Choe, Wonho [Department of Physics, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)] [Department of Physics, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Seon, Jongho [School of Space Research, Kyung Hee University, 1732 Deokyoungdaero, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of)] [School of Space Research, Kyung Hee University, 1732 Deokyoungdaero, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); June Lee, Hae [Department of Electrical Engineering, Pusan National University, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan 609-735 (Korea, Republic of)] [Department of Electrical Engineering, Pusan National University, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan 609-735 (Korea, Republic of)
2013-09-23T23:59:59.000Z
Investigation of the radial scale effect on low-power cylindrical Hall thrusters has been undertaken by comparing the thrusters with three different channel diameters of 28, 40, and 50 mm. The investigation found that both the anode efficiency and the thrust of the larger thruster are higher as the anode power is raised. On the other hand, higher current and propellant utilizations are achieved for the smaller thruster, which is due to higher neutral density and better electron confinement. The large plume angle of the small cylindrical Hall thruster causes thrust loss, resulting in the reduction of anode efficiency.
Experimental evidences of a large extrinsic spin Hall effect in AuW alloy
Laczkowski, P.; Rojas-Sánchez, J.-C. [Unité Mixte de Physique CNRS/Thales and Université Paris-Sud 11, 91767 Palaiseau (France); INAC/SP2M, CEA-Université Joseph Fourier, F-38054 Grenoble (France); Savero-Torres, W.; Notin, L.; Beigné, C.; Marty, A.; Attané, J.-P.; Vila, L. [INAC/SP2M, CEA-Université Joseph Fourier, F-38054 Grenoble (France); Jaffrès, H.; Reyren, N.; Deranlot, C.; George, J.-M.; Fert, A. [Unité Mixte de Physique CNRS/Thales and Université Paris-Sud 11, 91767 Palaiseau (France)
2014-04-07T23:59:59.000Z
We report an experimental study of a gold-tungsten alloy (7 at. % W concentration in Au host) displaying remarkable properties for spintronics applications using both magneto-transport in lateral spin valve devices and spin-pumping with inverse spin Hall effect experiments. A very large spin Hall angle of about 10% is consistently found using both techniques with the reliable spin diffusion length of 2?nm estimated by the spin sink experiments in the lateral spin valves. With its chemical stability, high resistivity, and small induced damping, this AuW alloy may find applications in the nearest future.
Effects of ionization distribution on plasma beam focusing characteristics in Hall thrusters
Ning Zhongxi; Liu Hui; Yu Daren [Plasma Propulsion Laboratory, Harbin Institute of Technology, Harbin 150001 (China); Zhou Zhongxiang [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China)
2011-11-28T23:59:59.000Z
The relationship between ionization distribution and divergence of plasma beam in a Hall thruster is investigated using spectrum and probe methods. Experimental results indicate that the shift of ionization region towards the exit of channel causes the reduction of accelerating field and the enhancement of electron thermal pressure effect, which result in further deviation of equipotential lines to magnetic field lines and further increase in divergence of plasma beam. It is, therefore, suggested that to put the ionization region deep inside the channel and separate it from the acceleration region at the design, and development stage is helpful to improve the plasma beam focusing characteristics of a Hall thruster.
Technique to Collimate Ions in a Hall-Effect Thruster Discharge Chamber
Walker, Mitchell
Technique to Collimate Ions in a Hall-Effect Thruster Discharge Chamber Kunning G. Xu and Mitchell in the discharge chamber to repel ions away from the wall and focus them toward centerline. The electrodes repel ions with trajectories that intersect the chamber wall, which results in a more collimated ion exhaust
Plasma-Induced Erosion on Ceramic Wall Structures in Hall-Effect Thrusters
Walker, Mitchell
Plasma-Induced Erosion on Ceramic Wall Structures in Hall-Effect Thrusters Thomas Burton University expansion of BN in the amorphous silica matrix. Exfoliation accompanied the microcracking in BN and resulted]. There have been several studies on ion-based erosion in ceramic materials [58,1017]. The mechanisms
Discharge Oscillations in a Permanent Magnet Cylindrical Hall-Effect Thruster
circuit leaves very little room for magnetic pole pieces and heat shields. Propulsion Research EngineerDischarge Oscillations in a Permanent Magnet Cylindrical Hall-Effect Thruster IEPC-2009-122 Presented at the 31st International Electric Propulsion Conference, Ann Arbor, MI September 20-24, 2009 K
Paris-Sud XI, Université de
-temperature Hall effect in rare earth metals M. V. Vedernikov, V. G. Dvunitkin and N. I. Moreva A. F. Ioffe. Abstract. - Up to date the Hall effect in rare earth metals (REM) was studied rather extensively below at http://dx.doi.org/10.1051/jphyscol:1979518 #12;HIGH-TEMPERATURE HALL EFFECT IN RARE EARTH METALS C5
Tang, Chiu-Chun [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Ling, D. C. [Department of Physics, Tamkang University, Tamsui Dist., New Taipei City 25137, Taiwan (China); Chi, C. C.; Chen, Jeng-Chung [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30013, Taiwan (China)
2014-11-03T23:59:59.000Z
We have developed a highly tunable, narrow band far-infrared (FIR) photodetector which utilizes the characteristic merits of graphene and two-dimensional electron gas (2DEG) in GaAs/Al{sub x}Ga{sub 1?x}As heterostructure in the Quantum Hall states (QHS). The heterostructure surface is covered with chemical vapor-deposited graphene, which functions as a transparent top-gate to vary the electron density of the 2DEG. FIR response observed in the vicinity of integer QH regime can be effectively tuned in a wide range of 27–102?cm{sup ?1} with a bias voltage less than ?1?V. In addition, we have found that the presence of graphene can genuinely modulate the photoresponse. Our results demonstrate a promising direction for realizing a tunable long-wavelength FIR detector using QHS in GaAs 2DEG/ graphene composite material.
Cobden, David
dox 25 nm and a range of effective channel dimensions L and W from 0.4 to 4 mm [9]. Each device on the metallic polysilicon gate: dr dVg C e 8.6 3 1011 cm22 V21 , where C eoxe0 dox and eox 3.9 [13
Determination of the Pt spin diffusion length by spin-pumping and spin Hall effect
Zhang, Wei; Pearson, John E.; Hoffmann, Axel [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Vlaminck, Vincent [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States) [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Colegio de Ciencias e Ingenería, Universidad San Fransciso de Quito, Quito (Ecuador); Divan, Ralu [Center for Nanoscale Materials, Argonne National Laboratory, Illinois 60439 (United States)] [Center for Nanoscale Materials, Argonne National Laboratory, Illinois 60439 (United States); Bader, Samuel D. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States) [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Center for Nanoscale Materials, Argonne National Laboratory, Illinois 60439 (United States)
2013-12-09T23:59:59.000Z
The spin diffusion length of Pt at room temperature and at 8 K is experimentally determined via spin pumping and spin Hall effect in permalloy/Pt bilayers. Voltages generated during excitation of ferromagnetic resonance from the inverse spin Hall effect and anisotropic magnetoresistance effect were investigated with a broadband approach. Varying the Pt layer thickness gives rise to an evolution of the voltage line shape due to the superposition of the above two effects. By studying the ratio of the two voltage components with the Pt layer thickness, the spin diffusion length of Pt can be directly extracted. We obtain a spin diffusion length of ?1.2 nm at room temperature and ?1.6 nm at 8 K.
arXiv:1007.2404v1[cond-mat.mes-hall]14Jul2010 Electrostatically defined Quantum Dots in a Si/SiGe
Ludwig-Maximilians-Universität, München
arXiv:1007.2404v1[cond-mat.mes-hall]14Jul2010 Electrostatically defined Quantum Dots in a Si/SiGe (QD) realized in a molecular beam epitaxy grown Si/SiGe heterostructure. Transport and charge as a spin qubit. Our results promise the suitability of electrostatically defined QDs in Si/SiGe
PREPRINT QUASIPARTICLE AGGREGATION I N THE FRACTIONAL QUANTUM HALL EFFECT
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible for RenewableSpeedingBiomassPPPO Website Directory PPPO WebsitePREP | National
Robert B. Laughlin and the Fractional Quantum Hall Effect
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's PossibleRadiation Protection TechnicalResonantNovember 15 to March 15ARiskSands2008 FellowsRobert
Sandia Energy - Second Generation Fractional Quantum Hall Effect
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's PossibleRadiationImplementing Nonlinear757KelleyEffectson the Cover of AdvancedPhotovoltaicSecond
Effect of electron temperature anisotropy on near-wall conductivity in Hall thrusters
Zhang, Fengkui, E-mail: fengkuizhang@163.com, E-mail: yudaren@hit.edu.cn; Kong, Lingyi; Zhang, Xueyi; Li, Wei [College of Aerospace and Civil Engineering, Harbin Engineering University, Harbin 150001 (China); Yu, Daren, E-mail: fengkuizhang@163.com, E-mail: yudaren@hit.edu.cn [College of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)
2014-06-15T23:59:59.000Z
The electron velocity distribution in Hall thrusters is anisotropic, which not only makes the sheath oscillate in time, but also causes the sheath to oscillate in space under the condition of low electron temperatures. The spatial oscillation sheath has a significant effect on near-wall transport current. In this Letter, the method of particle-in-cell (2D?+?3?V) was adopted to simulate the effect of anisotropic electron temperatures on near-wall conductivity in a Hall thruster. Results show that the electron-wall collision frequency is within the same order in magnitude for both anisotropic and isotropic electron temperatures. The near-wall transport current produced by collisions between the electrons and the walls is much smaller than experimental measurements. However, under the condition of anisotropic electron temperatures, the non-collision transport current produced by slow electrons which reflected by the spatial oscillation sheath is much larger and closes to measurements.
Rivest, Christopher W. (Christopher Warren)
2006-01-01T23:59:59.000Z
A novel dual differential hall-effect based proving ring force sensor has been designed, manufactured, and tested. Strain gauge based force sensors are among the most common methods of measuring static and dynamic forces, ...
Effective equations for quantum dynamics
Benjamin Schlein
2012-08-01T23:59:59.000Z
We report on recent results concerning the derivation of effective evolution equations starting from many body quantum dynamics. In particular, we obtain rigorous derivations of nonlinear Hartree equations in the bosonic mean field limit, with precise bounds on the rate of convergence. Moreover, we present a central limit theorem for the fluctuations around the Hartree dynamics.
All-optical Hall effect by the dynamic toroidal moment in a cavity-based metamaterial
Dong, Zheng-Gao; Yin, Xiaobo; Li, Jiaqi; Lu, Changgui; Zhang, Xiang
2013-01-01T23:59:59.000Z
Dynamic dipolar toroidal response is demonstrated by an optical plasmonic metamaterial composed of double disks. This response with a hotspot of localized E-field concentration is a well-behaved toroidal cavity mode that exhibits a large Purcell factor due to its deep-subwavelength mode volume. All-optical Hall effect (photovoltaic) due to this optical toroidal moment is demonstrated numerically, in mimicking the magnetoelectric effect in multiferroic systems. The result shows a promising avenue to explore various optical phenomena associated with this intriguing dynamic toroidal moment.
Inverse spin Hall effect induced by spin pumping into semiconducting ZnO
Lee, Jung-Chuan [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Huang, Leng-Wei [Graduate Institute of Applied Physics, National Chengchi University, Taipei 11605, Taiwan (China); Hung, Dung-Shing, E-mail: dshung@mail.mcu.edu.tw [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Department of Information and Telecommunications Engineering, Ming Chuan University, Taipei 111, Taiwan (China); Chiang, Tung-Han [Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan (China); Huang, J. C. A., E-mail: jcahuang@mail.ncku.edu.tw [Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Liang, Jun-Zhi [Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Department of Physics, Fu Jen Catholic University, Taipei 242, Taiwan (China); Lee, Shang-Fan, E-mail: leesf@phys.sinica.edu.tw [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Graduate Institute of Applied Physics, National Chengchi University, Taipei 11605, Taiwan (China)
2014-02-03T23:59:59.000Z
The inverse spin Hall effect (ISHE) of n-type semiconductor ZnO thin films with weak spin-orbit coupling has been observed by utilizing the spin pumping method. In the ferromagnetic resonance condition, the spin pumping driven by the dynamical exchange interaction of a permalloy film injects a pure spin current into the adjacent ZnO layer. This spin current gives rise to a DC voltage through the ISHE in the ZnO layer, and the DC voltage is proportional to the microwave excitation power. The effect is sizeable even when the spin backflow is considered.
Knight, S; Darakchieva, V; Kühne, P; Carlin, J -F; Grandjean, N; Herzinger, C M; Schubert, M; Hofmann, T
2015-01-01T23:59:59.000Z
The effect of a tunable, externally coupled Fabry-P\\'{e}rot cavity to resonantly enhance the optical Hall effect signatures at terahertz frequencies produced by a traditional Drude-like two-dimensional electron gas is shown and discussed in this communication. As a result, the detection of optical Hall effect signatures at conveniently obtainable magnetic fields, for example by neodymium permanent magnets, is demonstrated. An AlInN/GaN-based high electron mobility transistor structure grown on a sapphire substrate is used for the experiment. The optical Hall effect signatures and their dispersions, which are governed by the frequency and the reflectance minima and maxima of the externally coupled Fabry-P\\'{e}rot cavity, are presented and discussed. Tuning the externally coupled Fabry-P\\'{e}rot cavity strongly modifies the optical Hall effect signatures, which provides a new degree of freedom for optical Hall effect experiments in addition to frequency, angle of incidence and magnetic field direction and stren...
Quantum mechanical effects from deformation theory
Much, A. [Max-Planck-Institute for Mathematics in the Sciences, 04103 Leipzig, Germany and Institute for Theoretical Physics, University of Leipzig, 04009 Leipzig (Germany)] [Max-Planck-Institute for Mathematics in the Sciences, 04103 Leipzig, Germany and Institute for Theoretical Physics, University of Leipzig, 04009 Leipzig (Germany)
2014-02-15T23:59:59.000Z
We consider deformations of quantum mechanical operators by using the novel construction tool of warped convolutions. The deformation enables us to obtain several quantum mechanical effects where electromagnetic and gravitomagnetic fields play a role. Furthermore, a quantum plane can be defined by using the deformation techniques. This in turn gives an experimentally verifiable effect.
Nuclear quantum effects in water
Joseph A. Morrone; Roberto Car
2008-03-25T23:59:59.000Z
In this work, a path integral Car-Parrinello molecular dynamics simulation of liquid water is performed. It is found that the inclusion of nuclear quantum effects systematically improves the agreement of first principles simulations of liquid water with experiment. In addition, the proton momentum distribution is computed utilizing a recently developed open path integral molecular dynamics methodology. It is shown that these results are in good agreement with neutron Compton scattering data for liquid water and ice.
Temperature-driven band inversion in Pb?.??Sn?.??Se: Optical and Hall-effect studies
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Anand, Naween; Gu, Genda; Buvaev, Sanal; Hebard, A. F.; Tanner, D. B.; Chen, Zhiguo; Li, Zhiqiang; Choudhary, Kamal; Sinnott, S. B.; Martin, C.
2014-12-01T23:59:59.000Z
Optical and Hall-effect measurements have been performed on single crystals of Pb?.??Sn?.??Se, a IV-VI mixed chalcogenide. The temperature dependent (10–300 K) reflectance was measured over 40–7000 cm?¹ (5–870 meV) with an extension to 15,500 cm?¹ (1.92 eV) at room temperature. The reflectance was fit to the Drude-Lorentz model using a single Drude component and several Lorentz oscillators. The optical properties at the measured temperatures were estimated via Kramers-Kronig analysis as well as by the Drude-Lorentz fit. The carriers were p-type with the carrier density determined by Hall measurements. A signature of valence intraband transition is found in the low-energy opticalmore »spectra. It is found that the valence-conduction band transition energy as well as the free carrier effective mass reach minimum values at 100 K, suggesting temperature-driven band inversion in the material. Density function theory calculation for the electronic band structure also make similar predictions.« less
Resonant cavity mode dependence of anomalous and inverse spin Hall effect
Kim, Sang-Il; Seo, Min-Su; Park, Seung-young, E-mail: parksy@kbsi.re.kr [Division of Materials Science, Korea Basic Science Institute, Daejeon 305-806 (Korea, Republic of)
2014-05-07T23:59:59.000Z
The direct current electric voltage induced by the Inverse Spin Hall Effect (ISHE) and Anomalous Hall Effect (AHE) was investigated in the TE{sub 011} and TE{sub 102} cavities. The ISHE and AHE components were distinguishable through the fitting of the voltage spectrum. The unwanted AHE was minimized by placing the DUT (Device Under Test) at the center of both the TE{sub 011} and TE{sub 102} cavities. The voltage of ISHE in the TE{sub 011} cavity was larger than that in the TE{sub 102} cavity due to the higher quality factor of the former. Despite optimized centering, AHE voltage from TE{sub 011} cavity was also higher. The reason was attributed to the E-field distribution inside the cavity. In the case of the TE{sub 011} cavity, the DUT was easily exposed to the E-field in all directions. Therefore, the parasitic AHE voltage in the TE{sub 102} cavity was less sensitive than that in the TE{sub 011} cavity to decentering problem.
Temperature-driven band inversion in Pb?.??Sn?.??Se: Optical and Hall-effect studies
Anand, Naween [Univ. of Florida, Gainesville, FL (United States); Gu, Genda [Brookhaven National Lab. (BNL), Upton, NY (United States); Buvaev, Sanal [Univ. of Florida, Gainesville, FL (United States); Hebard, A. F. [Univ. of Florida, Gainesville, FL (United States); Tanner, D. B. [Univ. of Florida, Gainesville, FL (United States); Chen, Zhiguo [Florida State Univ., Tallahassee, FL (United States); Li, Zhiqiang [Florida State Univ., Tallahassee, FL (United States); Choudhary, Kamal [Univ. of Florida, Gainesville, FL (United States); Sinnott, S. B. [Univ. of Florida, Gainesville, FL (United States); Martin, C. [Ramapo College, Mahwah, NJ (United States)
2014-12-01T23:59:59.000Z
Optical and Hall-effect measurements have been performed on single crystals of Pb?.??Sn?.??Se, a IV-VI mixed chalcogenide. The temperature dependent (10–300 K) reflectance was measured over 40–7000 cm?¹ (5–870 meV) with an extension to 15,500 cm?¹ (1.92 eV) at room temperature. The reflectance was fit to the Drude-Lorentz model using a single Drude component and several Lorentz oscillators. The optical properties at the measured temperatures were estimated via Kramers-Kronig analysis as well as by the Drude-Lorentz fit. The carriers were p-type with the carrier density determined by Hall measurements. A signature of valence intraband transition is found in the low-energy optical spectra. It is found that the valence-conduction band transition energy as well as the free carrier effective mass reach minimum values at 100 K, suggesting temperature-driven band inversion in the material. Density function theory calculation for the electronic band structure also make similar predictions.
Wu Zhiwen; Liu Xiangyang; Wang Ningfei [School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China); Yu Daren [Harbin Plasma Propulsion Lab, Mail Box 458, Harbin Institute of Technology, Harbin 150001 (China)
2010-07-15T23:59:59.000Z
The effect of magnetic lens on the electron current due to near wall conductivity (NWC) in a Hall thruster is studied. A Monte Carlo model is employed to simulate the effect of the large magnetic field incidence angle on the electron current. The simulation results show that the electron current due to NWC decreases in the case of large incidence. The simulation qualitatively agrees with the related experimental result. And the simulation also demonstrates that choosing the curvature angle of the magnetic field is also a key factor to design a Hall thruster with high operation performance.
3D Quantum Gravity and Effective Noncommutative Quantum Field Theory
Freidel, Laurent; Livine, Etera R. [Perimeter Institute, 31 Caroline Street, North Waterloo, Ontario N2L 2Y5, Canada, and Laboratoire de Physique, ENS Lyon, CNRS UMR 5672, 46 Allee d'Italie, 69364 Lyon Cedex 07 (France)
2006-06-09T23:59:59.000Z
We show that the effective dynamics of matter fields coupled to 3D quantum gravity is described after integration over the gravitational degrees of freedom by a braided noncommutative quantum field theory symmetric under a {kappa} deformation of the Poincare group.
Effects of magnetic field strength on the low frequency oscillation in Hall thrusters
Wang Chunsheng; Wei Liqiu; Ning Zhongxi; Yu Daren [Laboratory of Plasma Propulsion, Mail Box 458, Harbin Institute of Technology, Harbin 150001 (China)
2011-01-15T23:59:59.000Z
In order to study the effect of magnetic field strength on low frequency oscillation in Hall thrusters, experiments were carried out with different operating parameters. Experimental results show that the effect of magnetic field strength on the low frequency oscillation changes with operating parameters. In the decline zone of magnetoampere characteristic curve, low frequency oscillation increases with the increase of magnetic field strength at low mass flow rate, while decreases with the increase of magnetic field strength at high mass flow rate. With further experiments and numerical simulations, it is found that the change of electron current at low mass flow rate and the change of ion current at high mass flow rate account for the variations of low frequency oscillation. Finally, the physical analysis is performed.
Dynamical Casimir Effect in Quantum Information Processing
Giuliano Benenti; Antonio D'Arrigo; Stefano Siccardi; Giuliano Strini
2014-07-28T23:59:59.000Z
We demonstrate, in the regime of ultrastrong matter-field coupling, the strong connection between the dynamical Casimir effect (DCE) and the performance of quantum information protocols. Our results are illustrated by means of a realistic quantum communication channel and show that the DCE is a fundamental limit for quantum computation and communication and that novel schemes are required to implement ultrafast and reliable quantum gates. Strategies to partially counteract the DCE are also discussed.
Effect of the annular region on the performance of a cylindrical Hall plasma thruster
Seo, Mihui; Lee, Jongsub; Choe, Wonho [Department of Physics, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Seon, Jongho [School of Space Research, Kyung Hee University, 1732 Deokyoungdaero, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); June Lee, Hae [Department of Electrical Engineering, Pusan National University, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan 609-735 (Korea, Republic of)
2013-02-15T23:59:59.000Z
Performance characteristics of a cylindrical Hall thruster depending on the depth of the annular region (L{sub a}) in front of the anode were investigated. The effect of the annular region was examined by operating thrusters corresponding to four different values of L{sub a} (0, 4, 6, and 10 mm) and a fixed length of the cylindrical region (25 mm). Various measurements such as electron and ion currents, thrust, anode efficiency, current and propellant utilizations, and ion energy distribution functions were performed. Such measurements lead to an interpretation that (1) a considerable potential difference may exist between the anode and the ionization region, which is presumably located near the end of the annular region where magnetic field lines converge; (2) this potential difference increases with respect to increasing L{sub a}; and (3) the presence of the annular region near the anode reduces the specific impulse and anode efficiency for the examined thrusters.
Mosendz, O.; Vlaminck, V.; Pearson, J. E.; Fradin, F. Y.; Bauer, G. E. W.; Bader, S. D.; Hoffmann, A.; Delft Univ. of Technology
2010-12-01T23:59:59.000Z
Spin pumping is a mechanism that generates spin currents from ferromagnetic resonance over macroscopic interfacial areas, thereby enabling sensitive detection of the inverse spin Hall effect that transforms spin into charge currents in nonmagnetic conductors. Here we study the spin-pumping-induced voltages due to the inverse spin Hall effect in permalloy/normal metal bilayers integrated into coplanar waveguides for different normal metals and as a function of angle of the applied magnetic field direction, as well as microwave frequency and power. We find good agreement between experimental data and a theoretical model that includes contributions from anisotropic magnetoresistance and inverse spin Hall effect. The analysis provides consistent results over a wide range of experimental conditions as long as the precise magnetization trajectory is taken into account. The spin Hall angles for Pt, Pd, Au, and Mo were determined with high precision to be 0.013 {+-} 0.002, 0.0064 {+-} 0.001, 0.0035 {+-} 0.0003, and -0.0005 {+-} 0.0001, respectively.
Quantum Field Theory in Graphene
I. V. Fialkovsky; D. V. Vassilevich
2011-11-18T23:59:59.000Z
This is a short non-technical introduction to applications of the Quantum Field Theory methods to graphene. We derive the Dirac model from the tight binding model and describe calculations of the polarization operator (conductivity). Later on, we use this quantity to describe the Quantum Hall Effect, light absorption by graphene, the Faraday effect, and the Casimir interaction.
Parallelization of particle-in-cell simulation modeling Hall-effect thrusters
Fox, Justin M., 1981-
2005-01-01T23:59:59.000Z
MIT's fully kinetic particle-in-cell Hall thruster simulation is adapted for use on parallel clusters of computers. Significant computational savings are thus realized with a predicted linear speed up efficiency for certain ...
Large anomalous Hall effect in ferromagnetic insulator-topological insulator heterostructures
Alegria, L. D.; Petta, J. R. [Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States); Ji, H.; Cava, R. J. [Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (United States); Yao, N. [Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544 (United States); Clarke, J. J. [Hitachi High Technologies America, Inc., Clarksburg, Maryland 20871 (United States)
2014-08-04T23:59:59.000Z
We demonstrate the van der Waals epitaxy of the topological insulator compound Bi{sub 2}Te{sub 3} on the ferromagnetic insulator Cr{sub 2}Ge{sub 2}Te{sub 6}. The layers are oriented with (001)Bi{sub 2}Te{sub 3}||(001)Cr{sub 2}Ge{sub 2}Te{sub 6} and (110)Bi{sub 2}Te{sub 3}||(100)Cr{sub 2}Ge{sub 2}Te{sub 6}. Cross-sectional transmission electron microscopy indicates the formation of a sharp interface. At low temperatures, bilayers consisting of Bi{sub 2}Te{sub 3} on Cr{sub 2}Ge{sub 2}Te{sub 6} exhibit a large anomalous Hall effect (AHE). Tilted field studies of the AHE indicate that the easy axis lies along the c-axis of the heterostructure, consistent with magnetization measurements in bulk Cr{sub 2}Ge{sub 2}Te{sub 6}. The 61?K Curie temperature of Cr{sub 2}Ge{sub 2}Te{sub 6} and the use of near-stoichiometric materials may lead to the development of spintronic devices based on the AHE.
Optimal tunneling enhances the quantum photovoltaic effect in double quantum dots
Wang, Chen
We investigate the quantum photovoltaic effect in double quantum dots by applying the nonequilibrium quantum master equation. A drastic suppression of the photovoltaic current is observed near the open circuit voltage, ...
Ludwig-Maximilians-UniversitÃ¤t, MÃ¼nchen
resolution well below typical Hall bar dimensions,7,8 the other is the use of the edge channels them- selves are as follows: Buffer and smoothing layers, 1 m GaAs, a 15-nm AlxGa1 xAs (x 0.3) spacer layer, 3.9 1012 - cm 2
Cost-Effective Fabrication Routes for the Production of Quantum...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Production of Quantum Well Type Structures and Recovery of Waste Heat from Heavy Duty Trucks Cost-Effective Fabrication Routes for the Production of Quantum Well Type Structures...
Classification of macroscopic quantum effects
Tristan Farrow; Vlatko Vedral
2014-06-03T23:59:59.000Z
We review canonical experiments on systems that have pushed the boundary between the quantum and classical worlds towards much larger scales, and discuss their unique features that enable quantum coherence to survive. Because the types of systems differ so widely, we use a case by case approach to identifying the different parameters and criteria that capture their behaviour in a quantum mechanical framework. We find it helpful to categorise systems into three broad classes defined by mass, spatio-temporal coherence, and number of particles. The classes are not mutually exclusive and in fact the properties of some systems fit into several classes. We discuss experiments by turn, starting with interference of massive objects like macromolecules and micro-mechanical resonators, followed by self-interference of single particles in complex molecules, before examining the striking advances made with superconducting qubits. Finally, we propose a theoretical basis for quantifying the macroscopic features of a system to lay the ground for a more systematic comparison of the quantum properties in disparate systems.
Quantum plasma effects in the classical regime
G. Brodin; M. Marklund; G. Manfredi
2008-02-01T23:59:59.000Z
For quantum effects to be significant in plasmas it is often assumed that the temperature over density ratio must be small. In this paper we challenge this assumption by considering the contribution to the dynamics from the electron spin properties. As a starting point we consider a multicomponent plasma model, where electrons with spin up and spin down are regarded as different fluids. By studying the propagation of Alfv\\'{e}n wave solitons we demonstrate that quantum effects can survive in a relatively high-temperature plasma. The consequences of our results are discussed.
On the R\\^ole of a Torsion-like Field in a Scenario for the Spin Hall Effect
Godinho, C F L
2014-01-01T23:59:59.000Z
Starting from an action that describes a Dirac fermion, we propose and analyze a model based on a low-relativistic Pauli equation coupled to a torsion-like term to study Spin Hall Effect (SHE). We point out a very particular connection between the modified Pauli equation and the (SHE), where what we refer to torsion as field playing an important r\\^ole in the spin-orbit coupling process. In this scenario, we present a proposal of a spin-type current, considering the tiny contributions of torsion in connection with geometrical properties of the material.
Wall current closure effects on plasma and sheath fluctuations in Hall thrusters
Frias, Winston, E-mail: wpf274@mail.usask.ca; Smolyakov, Andrei I. [Department of Physics and Engineering Physics, University of Saskatchewan, 116 Science Place, Saskatoon, Saskatchewan S7N 5E2 (Canada); Kaganovich, Igor D.; Raitses, Yevgeny [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
2014-06-15T23:59:59.000Z
The excitation of negative energy, ion sound type modes driven by the E?×?B drift and the reactive/dissipative response of the wall sheath interface is analyzed for conditions typical in a Hall thruster. Such sheath impedance modes are sensitive to the dielectric properties of the thruster wall material, which therefore may have direct influence (other than via the secondary electron emission) on fluctuations and transport. Our results predict mode frequencies consistent with the frequencies of fluctuations observed experimentally.
Demir, Hilmi Volkan
Blue quantum electroabsorption modulators based on reversed quantum confined Stark effect of blue quantum electroabsorption modulators that incorporate 5 nm thick In0.35Ga0.65N/GaN quantum cm-1 for 6 V bias swing around 424 nm, holding promise for blue optical clock generation
Chowdhury, Debashree, E-mail: debashreephys@gmail.com; Basu, B., E-mail: sribbasu@gmail.com
2013-02-15T23:59:59.000Z
We have studied the spin dependent force and the associated momentum space Berry curvature in an accelerating system. The results are derived by taking into consideration the non-relativistic limit of a generally covariant Dirac equation with an electromagnetic field present, where the methodology of the Foldy-Wouthuysen transformation is applied to achieve the non-relativistic limit. Spin currents appear due to the combined action of the external electric field, the crystal field and the induced inertial electric field via the total effective spin-orbit interaction. In an accelerating frame, the crucial role of momentum space Berry curvature in the spin dynamics has also been addressed from the perspective of spin Hall conductivity. For time dependent acceleration, the expression for the spin polarization has been derived. - Highlights: Black-Right-Pointing-Pointer We study the effect of acceleration on the Dirac electron in the presence of an electromagnetic field, where the acceleration induces an electric field. Black-Right-Pointing-Pointer Spin currents appear due to the total effective electric field via the total spin-orbit interaction. Black-Right-Pointing-Pointer We derive the expression for the spin dependent force and the spin Hall current, which is zero for a particular acceleration. Black-Right-Pointing-Pointer The role of the momentum space Berry curvature in an accelerating system is discussed. Black-Right-Pointing-Pointer An expression for the spin polarization for time dependent acceleration is derived.
Effective Evolution Equations from Quantum Dynamics
Niels Benedikter; Marcello Porta; Benjamin Schlein
2015-02-09T23:59:59.000Z
In these notes we review the material presented at the summer school on "Mathematical Physics, Analysis and Stochastics" held at the University of Heidelberg in July 2014. We consider the time-evolution of quantum systems and in particular the rigorous derivation of effective equations approximating the many-body Schr\\"odinger dynamics in certain physically interesting regimes.
Wang, Hailong; Du, Chunhui; Chris Hammel, P., E-mail: hammel@physics.osu.edu; Yang, Fengyuan, E-mail: fyyang@physics.osu.edu [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States)
2014-05-19T23:59:59.000Z
Using ferromagnetic (FM) resonance spin pumping, we observe injection of spin currents from Y{sub 3}Fe{sub 5}O{sub 12} (YIG) films to FM metals, including Ni{sub 81}Fe{sub 19} (Py), Fe, Co, and Ni, and detection of spin currents by inverse spin Hall effect (ISHE) in the FM metals. We obtain a high effective spin mixing conductance of 6.3?×?10{sup 18}?m{sup ?2} in a YIG/Cu/Py trilayer and a spin Hall angle of 0.020 for Py. The spin pumping signals in Fe, Co, and Ni confirm the mechanism of ISHE in FMs is the inverse process of the anomalous Hall effect.
.......Agnew Hall .......Air Conditioning Facility
Buehrer, R. Michael
/Burleson Tennis Center .......Burruss Hall .......Campbell Hall .......Cassell Coliseum .......Central Stores .......Dietrick Hall .......Durham Hall .......Eggleston Hall .......Engel Hall D.....English Field .......Femoyer .......Golf Course Clubhouse .......Graduate Life Center at ........Donaldson Brown .......Greenhouses
Effect of trapping in degenerate quantum plasmas
Shah, H. A.; Qureshi, M. N. S. [Department of Physics, GC University, Lahore 54000 (Pakistan); Tsintsadze, N. [Department of Physics, GC University, Lahore 54000 (Pakistan); Salam Chair, GC University, Lahore 54000 (Pakistan)
2010-03-15T23:59:59.000Z
In the present work we consider the effect of trapping as a microscopic process in a plasma consisting of quantum electrons and nondegenerate ions. The formation of solitary structures is investigated in two cases: first when the electrons are fully degenerate and second when small temperature effects are taken into account. It is seen that not only rarefactive but coupled rarefactive and compressive solitons are obtained under different temperature conditions.
The Quantum-Classical and Mind-Brain Linkages: The Quantum Zeno Effect in Binocular Rivalry
Henry P. Stapp
2007-11-05T23:59:59.000Z
A quantum mechanical theory of the relationship between perceptions and brain dynamics based on von Neumann's theory of measurments is applied to a recent quantum theoretical treatment of binocular rivaly that makes essential use of the quantum Zeno effect to give good fits to the complex available empirical data. The often-made claim that decoherence effects in the warm, wet, noisy brain must eliminate quantum effects at the macroscopic scale pertaining to perceptions is examined, and it is argued, on the basis of fundamental principles. that the usual decoherence effects will not upset the quantum Zeno effect that is being exploited in the cited work.
Hankiewicz, EM; Li, J.; Jungwirth, T.; Niu, Q.; Shen, SQ; Sinova, Jairo.
2005-01-01T23:59:59.000Z
-current response generated perpendicular to the driving electric field. Recently, the spin Hall effect was experimentally ob- served by Kato et al.6 in n-doped GaAs using the Kerr effect and by Wunderlich et al.7 in the p-n junction light-emitting diodes based...
Disorder effects in the anomalous Hall effect induced by Berry curvature RID B-5617-2009
Sinitsyn, NA; Niu, Q.; Sinova, Jairo; Nomura, K.
2005-01-01T23:59:59.000Z
in ferromagnets results from the interplay of the ex- change field, which breaks the time-reversal symmetry, and the spin-orbit coupling, that violates the chiral symmetry. Interestingly, at the same time a similar effect was predicted and explained... of the distribution function in a single band at zero temperature: Jyx #1;clean#2; = e#8; d2kf0#1;k#2;vy#1;a#2; = e#8; 0 kF kdk#8; 0 2#5; d#6; #1;2#5;#2;2eExFz = e2ExFzkF 2 4#5; , #1;5#2; where f0#1;k#2; is the equilibrium distribution function and k...
Quantum anti-Zeno effect in artificial quantum systems
Qing Ai; Jie-Qiao Liao; C. P. Sun
2010-03-24T23:59:59.000Z
In this paper, we study a quantum anti-Zeno effect (QAZE) purely induced by repetitive measurements for an artificial atom interacting with a structured bath. This bath can be artificially realized with coupled resonators in one dimension and possesses photonic band structure like Bloch electron in a periodic potential. In the presence of repetitive measurements, the pure QAZE is discovered as the observable decay is not negligible even for the atomic energy level spacing outside of the energy band of the artificial bath. If there were no measurements, the decay would not happen outside of the band. In this sense, the enhanced decay is completely induced by measurements through the relaxation channels provided by the bath. Besides, we also discuss the controversial golden rule decay rates originated from the van Hove's singularities and the effects of the counter-rotating terms.
Grand Unification and Enhanced Quantum Gravitational Effects
Calmet, Xavier [Catholic University of Louvain, Center for Particle Physics and Phenomenology, 2, Chemin du Cyclotron, B-1348 Louvain-la-Neuve (Belgium); Hsu, Stephen D. H.; Reeb, David [Institute of Theoretical Science, University of Oregon, Eugene, Oregon 97403 (United States)
2008-10-24T23:59:59.000Z
In grand unified theories with large numbers of fields, renormalization effects significantly modify the scale at which quantum gravity becomes strong. This in turn can modify the boundary conditions for coupling constant unification, if higher dimensional operators induced by gravity are taken into consideration. We show that the generic size of, and the uncertainty in, these effects from gravity can be larger than the two-loop corrections typically considered in renormalization group analyses of unification. In some cases, gravitational effects of modest size can render unification impossible.
Quantum gravity effects in the Kerr spacetime
Reuter, M. [Institute of Physics, University of Mainz, Staudingerweg 7, D-55099 Mainz (Germany); Tuiran, E. [Departamento de Fisica, Universidad del Norte, Km 5 via a Puerto Colombia, AA-1569 Barranquilla (Colombia)
2011-02-15T23:59:59.000Z
We analyze the impact of the leading quantum gravity effects on the properties of black holes with nonzero angular momentum by performing a suitable renormalization group improvement of the classical Kerr metric within quantum Einstein gravity. In particular, we explore the structure of the horizons, the ergosphere, and the static limit surfaces as well as the phase space available for the Penrose process. The positivity properties of the effective vacuum energy-momentum tensor are also discussed and the 'dressing' of the black hole's mass and angular momentum are investigated by computing the corresponding Komar integrals. The pertinent Smarr formula turns out to retain its classical form. As for their thermodynamical properties, a modified first law of black-hole thermodynamics is found to be satisfied by the improved black holes (to second order in the angular momentum); the corresponding Bekenstein-Hawking temperature is not proportional to the surface gravity.
Cost-Effective Fabrication Routes for the Productionof Quantum...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Productionof Quantum-Well-Type Structures and Recovoery of Waste Heat from Heavy-Duty Trucks Cost-Effective Fabrication Routes for the Productionof Quantum-Well-Type Structures and...
Magnetic percolation and giant spontaneous Hall effect in La1 xCaxCoO3 ,,0.2 x 0.5... A. V. Samoilov
Yeh, Nai-Chang
Magnetic percolation and giant spontaneous Hall effect in La1 xCaxCoO3 ,,0.2 x 0.5... A. V and Center for Space Microelectronics Technology, Jet Propulsion Laboratory, California Institute Technology, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
Yu Daren; Li Hong; Ning Zhongxi; Yan Guojun [Laboratory of Plasma Propulsion, Mail Box 458, Harbin Institute of Technology, Harbin 150001 (China); Wu Zhiwen [School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083 (China)
2009-10-15T23:59:59.000Z
An experiment has been made to investigate the effect of curved magnetic field topology on near wall conductivity in the ion acceleration region of Hall thrusters. The experimental results show that the electron current due to near wall conductivity is of the minimum in the case of focused topology and increases in the cases of both less-focus and over-focus topologies. This finding cannot be explained properly by the magnetic mirror effect, which is the one and only reported effect related to the magnetic field curvature so far. Based on the analysis of interaction between the plasma and the wall, a new physical effect is proposed. The difference of magnetic field topology causes different electric potential distribution, leads to different ion flux to the wall, results in the change of sheath property and secondary electron emission, and finally affects the electron current due to near wall conductivity. This effect is further justified by the agreement between the experiment and simulation which is performed with a particle-in-cell model. Therefore, we conclude that the ion flow injection is a significant effect to near wall conductivity in the scope of curved magnetic field topology besides the magnetic mirror effect. Moreover, we find that the focus topology of magnetic field is favorable to obtain a high thruster performance from both the ion acceleration aspect and the electron conduction aspect and so is useful practically for thruster optimization.
Quantum confined Stark effect in Gaussian quantum wells: A tight-binding study
Ramírez-Morales, A.; Martínez-Orozco, J. C.; Rodríguez-Vargas, I. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad Esquina Con Paseo La Bufa S/N, 98060 Zacatecas, Zac. (Mexico)
2014-05-15T23:59:59.000Z
The main characteristics of the quantum confined Stark effect (QCSE) are studied theoretically in quantum wells of Gaussian profile. The semi-empirical tight-binding model and the Green function formalism are applied in the numerical calculations. A comparison of the QCSE in quantum wells with different kinds of confining potential is presented.
Quantum resistance standard accuracy close to the zero-dissipation state
Schopfer, F.; Poirier, W. [Laboratoire National de métrologie et d'Essais (LNE), 29 avenue Roger Hennequin, 78197 Trappes (France)] [Laboratoire National de métrologie et d'Essais (LNE), 29 avenue Roger Hennequin, 78197 Trappes (France)
2013-08-14T23:59:59.000Z
We report on a comparison of four GaAs/AlGaAs-based quantum resistance standards using an original technique adapted from the well-known Wheatstone bridge. This work shows that the quantized Hall resistance at Landau level filling factor ?=2 can be reproducible with a relative uncertainty of 32×10{sup ?12} in the dissipationless limit of the quantum Hall effect regime. In the presence of a very small dissipation characterized by a mean macroscopic longitudinal resistivity R{sub xx}(B) of a few ??, the discrepancy ?R{sub H}(B) between quantum Hall resistors measured on the Hall plateau at magnetic induction B turns out to follow the so-called resistivity rule R{sub xx}(B)=?B×d(?R{sub H}(B))/dB. While the dissipation increases with the measurement current value, the coefficient ? stays constant in the range investigated (40?120 ?A). This result enlightens the impact of the dissipation emergence in the two-dimensional electron gas on the Hall resistance quantization, which is of major interest for the resistance metrology. The quantum Hall effect is used to realize a universal resistance standard only linked to the electron charge e and the Planck constant h and it is known to play a central role in the upcoming revised Système International of units. There are therefore fundamental and practical benefits in testing the reproducibility property of the quantum Hall effect with better and better accuracy.
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over Our InstagramStructureProposedPAGESafetyTed5,AuditThe FiveBiofuelsGEThe H2The H2Hall
Topological Quantum Computation by Manipulating Quantum Tunneling Effect of the Toric Codes
Su-Peng Kou
2008-06-10T23:59:59.000Z
Quantum computers are predicted to utilize quantum states to perform memory and to process tasks far faster than those of conventional classical computers. In this paper we show a new road towards building fault tolerance quantum computer by tuning quantum tunneling effect of the degenerate quantum states in topological order, instead of by braiding anyons. Using a designer Hamiltonian - the Wen-Plaquette model as an example, we study its quantum tunneling effect of the toric codes and show how to control the toric code to realize topological quantum computation (TQC). In particular, we give a proposal to the measurement of TQC. In the end the realization of the Wen-Plaquette model in cold atoms is discussed.
The effective field theory treatment of quantum gravity
Donoghue, John F. [Department of Physics, University of Massachusetts, Amherst, MA 01003 (United States)
2012-09-24T23:59:59.000Z
This is a pedagogical introduction to the treatment of quantum general relativity as an effective field theory. It starts with an overview of the methods of effective field theory and includes an explicit example. Quantum general relativity matches this framework and I discuss gravitational examples as well as the limits of the effective field theory. I also discuss the insights from effective field theory on the gravitational effects on running couplings in the perturbative regime.
Weightlessness of photons: A quantum effect
Ari Brynjolfsson
2006-02-17T23:59:59.000Z
Contrary to general belief, the Fraunhofer lines have been found to be plasma redshifted and not gravitationally redshifted, when observed on Earth. Quantum mechanical effects cause the photons' gravitational redshift to be reversed as the photons move from the Sun to the Earth. The designs of the experiments, which were thought to have proven the gravitational redshift of photons, are all in the domain of classical physics, and make it impossible to detect the reversal of the gravitational redshifts. The solar redshift experiments, however, are in the domain of quantum mechanics; and the reversal of the redshift is easily detected, when the plasma redshift is taken into account. The photons are found to be weightless relative to a local observer, but repelled relative to a distant observer. The weightlessness of the photons in the gravitational field relative to a local observer is inconsistent with Einstein's equivalence principle. This together with the plasma redshift has profound consequences for the cosmological perspectives. This article gives a theoretical explanation of the observed phenomena, proper interpretation of the many gravitational redshift experiments, and an understanding of how we missed observing the reversal of photons' gravitational redshift. The present analysis indicates that although the photons are weightless in a local system of reference, the experimental evidence indicates that quasi-static electromagnetic fields are not weightless, but adhere to the principle of equivalence.
Bing Concert Hall, under construction
Houses Schwab Residential Center Lyman Graduate Residences Sterling Quad Mirrielees Pearce Mitchell Godzilla Thornton Center Bambi Roble Gym Terman Engineering Center Forsythe Hall Spruce Hall Cypress Hall
Busemeyer, Jerome R.
A skeptic would argue that it is quite a speculative leap to think that quantum probability can be appliedQuantum Model of Question Order Effects 1 Empirical test of a quantum probability model, 154 N. Oval Columbus, OH 43210 voice: (614) 247-8031 #12;Quantum Model of Question Order Effects 2
The Effects of Quantum Entropy on the Bag Constant
Miller, D E; Miller, David E.; Tawfik, Abdel-Nasser
2003-01-01T23:59:59.000Z
The effects of quantum entropy on the bag constant are studied at low temperatures and small chemical potentials. The inclusion of the quantum entropy of the quarks in the equation of state provides the hadronic bag with an additional heat which causes a decrease in the effective latent heat inside the bag. We have considered two types of baryonic bags, $\\Delta$ and $\\Omega^-$. In both cases we have found that the bag constant without the quantum entropy almost does not change with the temperature and the quark chemical potential. The contribution from the quantum entropy to the equation of state clearly decreases the value of the bag constant.
Ren, Yang; Yamada, Masaaki; Ji, Hantao; Dorfman, Seth; Gerhardt, Stefan; Kulsrud, Russel
2008-07-02T23:59:59.000Z
The Hall effect during magnetic reconnection without an external guide field has been extensively studied in the laboratory plasma of the Magnetic Reconnection Experiment (MRX) [Yamada et al., Phys. Plasmas 4, 1936 (1997)] by measuring its key signature, an out-of-plane quadrupole magnetic field, with magnetic probe arrays whose spatial resolution is on the order of the electron skin depth. The in-plane electron flow is deduced from out-of-plane magnetic field measurements. The measured in-plane electron flow and numerical results are in good agreement. The electron diffusion region is identified by measuring the electron outflow channel. The width of the electron diffusion region scales with the electron skin depth (~ 8c/?pe) and the peak electron outflow velocity scales with the electron Alfven velocity (~ 0:11VeA), independent of ion mass. The measured width of the electron diffusion region is much wider and the observed electron outflow is much slower than those obtained in 2D numerical simulations. It is found that the classical and anomalous dissipation present in the experiment can broaden the electron diffusion region and slow the electron outflow. As a consequence, the electron outflow flux remain consistent with numerical simulations. The ions, as measured by a Mach probe, have a much wider outflow channel than the electrons, and their outflow is much slower than the electron outflow everywhere in the electron diffusion region.
2D massless QED Hall half-integer conductivity and graphene
A. Pérez Martínez; E. Rodriguez Querts; H. Pérez Rojas; R. Gaitan; S. Rodriguez Romo
2011-10-13T23:59:59.000Z
Starting from the photon self-energy tensor in a magnetized medium, the 3D complete antisymmetric form of the conductivity tensor is found in the static limit of a fermion system $C$ non-invariant under fermion-antifermion exchange. The massless relativistic 2D fermion limit in QED is derived by using the compactification along the dimension parallel to the magnetic field. In the static limit and at zero temperature the main features of quantum Hall effect (QHE) are obtained: the half-integer QHE and the minimum value proportional to $e^2/h$ for the Hall conductivity . For typical values of graphene the plateaus of the Hall conductivity are also reproduced.
Quantum anomalous Hall effect with cold atoms trapped in a square lattice
Liu, Xiong-Jun; Liu, Xin; Wu, Congjun; Sinova, Jairo
2010-01-01T23:59:59.000Z
-JUN LIU, XIN LIU, CONGJUN WU, AND JAIRO SINOVA PHYSICAL REVIEW A 81, 033622 (2010) represent the edge and bulk states, respectively. The light Bragg scattering directly measures the dynamical structure factor [23]: S(q, ?) = ? ky1 ,ky2 { 1? f [E...| #1; q0 the dynamical structure takes the general form S(q, ?) ? (|q| + ky0 )#5;2?(? ? vF q) + #8;0 ?#5;20 2t2aba2 1+ 3h???/(2q0atab) [1+ h???/(q0atab)]2 ? ( pi 2 + sin?1 ?1/2|q ? q0|? h??? ) #15;(? ? ?c), (11) where ?? = ? ?#8;0/2h...
Emergent and reentrant fractional quantum Hall effect in trilayer systems in a tilted magnetic field
Gusev, Guennady
field G. M. Gusev,1 S. Wiedmann,2,3 O. E. Raichev,4 A. K. Bakarov,5 and J. C. Portal2,3,6 1Instituto de Physics, Novosibirsk 630090, Russia 6 Institut Universitaire de France, 75005 Paris, France Received 28
Igor Romanovsky; Constantine Yannouleas; Uzi Landman
2010-09-10T23:59:59.000Z
This paper (concerning the infinite-mass boundary condition) has been withdrawn by the author. Another, independent study regarding the zigzag boundary condition has appeared in Phys. Rev. B 82, 125419 (2010).
Quantum size effects in classical hadrodynamics
Nix, J.R.
1994-03-01T23:59:59.000Z
The author discusses future directions in the development of classical hydrodynamics for extended nucleons, corresponding to nucleons of finite size interacting with massive meson fields. This new theory provides a natural covariant microscopic approach to relativistic nucleus-nucleus collisions that includes automatically spacetime nonlocality and retardation, nonequilibrium phenomena, interactions among all nucleons, and particle production. The present version of the theory includes only the neutral scalar ({sigma}) and neutral vector ({omega}) meson fields. In the future, additional isovector pseudoscalar ({pi}{sup +}, {pi}{sup {minus}}, {pi}{sup 0}), isovector vector ({rho}{sup +}, {rho}{sup {minus}}, {rho}{sup 0}), and neutral pseudoscalar ({eta}) meson fields should be incorporated. Quantum size effects should be included in the equations of motion by use of the spreading function of Moniz and Sharp, which generates an effective nucleon mass density smeared out over a Compton wavelength. However, unlike the situation in electrodynamics, the Compton wavelength of the nucleon is small compared to its radius, so that effects due to the intrinsic size of the nucleon dominate.
Imperfection effects for multiple applications of the quantum wavelet transform
Marcello Terraneo; Dima L. Shepelyansky
2003-03-09T23:59:59.000Z
We study analytically and numerically the effects of various imperfections in a quantum computation of a simple dynamical model based on the Quantum Wavelet Transform (QWT). The results for fidelity timescales, obtained for a large range of error amplitudes and number of qubits, imply that for static imperfections the threshold for fault-tolerant quantum computation is decreased by a few orders of magnitude compared to the case of random errors.
A study of Quantum Correlation for Three Qubit States under the effect of Quantum Noisy Channels
Pratik K. Sarangi; Indranil Chakrabarty
2014-11-27T23:59:59.000Z
We study the dynamics of quantum dissension for three qubit states in various dissipative channels such as amplitude damping, dephasing and depolarizing. Our study is solely based on Markovian environments where quantum channels are without memory and each qubit is coupled to its own environment. We start with mixed GHZ, mixed W, mixture of separable states, a mixed biseparable state, as the initial states and mostly observe that the decay of quantum dissension is asymptotic in contrast to sudden death of quantum entanglement in similar environments. This is a clear indication of the fact that quantum correlation in general is more robust against the effect of noise. However, for a given class of initial mixed states we find a temporary leap in quantum dissension for a certain interval of time. More precisely, we observe the revival of quantum correlation to happen for certain time period. This signifies that the measure of quantum correlation such as quantum discord, quantum dissension, defined from the information theoretic perspective is different from the correlation defined from the entanglement-separability paradigm and can increase under the effect of the local noise. We also study the effects of these channels on the monogamy score of each of these initial states. Interestingly, we find that for certain class of states and channels, there is change from negative values to positive values of the monogamy score with classical randomness as well as with time. This gives us an important insight in obtaining states which are freely sharable (polygamous state) from the states which are not freely sharable (monogamous). This is indeed a remarkable feature, as we can create monogamous states from polygamous states Monogamous states are considered to have more signatures of quantum ness and can be used for security purpose.
TRINITY HALL PUBLICATION SCHEME
Lasenby, Joan
TRINITY HALL PUBLICATION SCHEME PART 2 Main categories The main groups of classes of information Trinity Hall was founded in 1350 by William Bateman, Bishop of Norwich, as a common law corporation to the University and College Statutes. The Education (Listed Bodies) Order 1997 recognises Trinity Hall
Monte Carlo simulation of quantum Zeno effect in the brain
Danko Georgiev
2014-12-11T23:59:59.000Z
Environmental decoherence appears to be the biggest obstacle for successful construction of quantum mind theories. Nevertheless, the quantum physicist Henry Stapp promoted the view that the mind could utilize quantum Zeno effect to influence brain dynamics and that the efficacy of such mental efforts would not be undermined by environmental decoherence of the brain. To address the physical plausibility of Stapp's claim, we modeled the brain using quantum tunneling of an electron in a multiple-well structure such as the voltage sensor in neuronal ion channels and performed Monte Carlo simulations of quantum Zeno effect exerted by the mind upon the brain in the presence or absence of environmental decoherence. The simulations unambiguously showed that the quantum Zeno effect breaks down for timescales greater than the brain decoherence time. To generalize the Monte Carlo simulation results for any n-level quantum system, we further analyzed the change of brain entropy due to the mind probing actions and proved a theorem according to which local projections cannot decrease the von Neumann entropy of the unconditional brain density matrix. The latter theorem establishes that Stapp's model is physically implausible but leaves a door open for future development of quantum mind theories provided the brain has a decoherence-free subspace.
Comparison of Secondary Islands in Collisional Reconnection to Hall Reconnection
Shepherd, L. S.; Cassak, P. A. [Department of Physics, West Virginia University, Morgantown, West Virginia, 26506 (United States)
2010-07-02T23:59:59.000Z
Large-scale resistive Hall-magnetohydrodynamic simulations of the transition from Sweet-Parker (collisional) to Hall (collisionless) magnetic reconnection are presented; the first to separate secondary islands from collisionless effects. Three main results are described. There exists a regime with secondary islands but without collisionless effects, and the reconnection rate is faster than Sweet-Parker, but significantly slower than Hall reconnection. This implies that secondary islands do not cause the fastest reconnection rates. The onset of Hall reconnection ejects secondary islands from the vicinity of the X line, implying that energy is released more rapidly during Hall reconnection. Coronal applications are discussed.
Wang, W. X. [State Key Laboratory of Advance Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wang, S. H.; Zou, L. K.; Cai, J. W.; Sun, J. R., E-mail: jrsun@iphy.ac.cn, E-mail: sun-zg@whut.edu.cn [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Sun, Z. G. [State Key Laboratory of Advance Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)
2014-11-03T23:59:59.000Z
Spin Seebeck effect (SSE) and spin Hall magnetoresistance (SMR) are observed simultaneously in the Pt/Y{sub 3}Fe{sub 5}O{sub 12} hybrid structure when thermal gradient is produced by Joule heating. According to their dependences on applied current, these two effects can be separated. Their dependence on heating power and magnetic field is systematically studied. With the increase of heating power, the SSE enhances linearly, whereas the SMR decreases slowly. The origin of the spin currents is further analyzed. The heating power dependences of the spin currents associated with the SSE and the SMR are found to be different.
Holographic Spontaneous Parity Breaking and Emergent Hall Viscosity and Angular Momentum
Dam Thanh Son; Chaolun Wu
2014-08-30T23:59:59.000Z
We study the spontaneous parity breaking and generating of Hall viscosity and angular momentum in holographic p+ip model, which can describe strongly-coupled chiral superfluid states in many quantum systems. The dual gravity theory, an SU(2) gauge field minimally coupled to Einstein gravity, is parity-invariant but allows a black hole solution with vector hair corresponding to a parity-broken superfluid state. We show that this state possesses a non-vanishing parity-odd transport coefficient -- Hall viscosity -- and an angular momentum density. We first develop an analytic method to solve this model near the critical regime and to take back-reactions into account. Then we solve the equation for the tensor mode fluctuations and obtain the expression for Hall viscosity via Kubo formula. We also show that a non-vanishing angular momentum density can be obtained through the vector mode fluctuations and the corresponding boundary action. We give analytic results of both Hall viscosity and angular momentum density near the critical regime in terms of physical parameters. The near-critical behavior of Hall viscosity is different from that obtained from a gravitational Chern-Simons model. We find that the magnitude of Hall viscosity to angular momentum density ratio is numerically consistent with being equal to 1/2 at large SU(2) coupling corresponding to the probe limit, in agreement with previous results obtained for various quantum fluid systems and from effective theory approaches. In addition, we find the shear viscosity to entropy density ratio remains above the universal bound.
Effective Field Theory of Fractional Quantized Hall Nematics | SciTech
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville Power AdministrationField Campaign:INEA :Work4/11ComputationalEdNERSC:Effect of SubgridConnect
Two quantum effects in the theory of gravitation
Robinson, Sean Patrick, 1977-
2005-01-01T23:59:59.000Z
We will discuss two methods by which the formalism of quantum field theory can be included in calculating the physical effects of gravitation. In the first of these, the consequences of treating general relativity as an ...
Gusev, Guennady
,2,3, G. M. Gusev4, A. K. Bakarov5, and J. C. Portal2,3 1 Radboud University Nijmegen, Institute~ao Paulo, SP, Brazil 5 Institute of Semiconductor Physics, Novosibirsk 630090, Russia E-mail: s
Quantum effects in electron beam pumped GaAs
Yahia, M. E. [Faculty of Engineering, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt) [Faculty of Engineering, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt); National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt); Azzouz, I. M. [National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt)] [National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt); Moslem, W. M. [Department of Physics, Faculty of Science, Port Said University, Port Said (Egypt)] [Department of Physics, Faculty of Science, Port Said University, Port Said (Egypt)
2013-08-19T23:59:59.000Z
Propagation of waves in nano-sized GaAs semiconductor induced by electron beam are investigated. A dispersion relation is derived by using quantum hydrodynamics equations including the electrons and holes quantum recoil effects, exchange-correlation potentials, and degenerate pressures. It is found that the propagating modes are instable and strongly depend on the electron beam parameters, as well as the quantum recoil effects and degenerate pressures. The instability region shrinks with the increase of the semiconductor number density. The instability arises because of the energetic electron beam produces electron-hole pairs, which do not keep in phase with the electrostatic potential arising from the pair plasma.
Low-Energy Effective Theories of Quantum Link and Quantum Spin Models
B. Schlittgen; U. -J. Wiese
2000-12-11T23:59:59.000Z
Quantum spin and quantum link models provide an unconventional regularization of field theory in which classical fields arise via dimensional reduction of discrete variables. This D-theory regularization leads to the same continuum theories as the conventional approach. We show this by deriving the low-energy effective Lagrangians of D-theory models using coherent state path integral techniques. We illustrate our method for the $(2+1)$-d Heisenberg quantum spin model which is the D-theory regularization of the 2-d O(3) model. Similarly, we prove that in the continuum limit a $(2+1)$-d quantum spin model with $SU(N)_L\\times SU(N)_R\\times U(1)_{L=R}$ symmetry is equivalent to the 2-d principal chiral model. Finally, we show that $(4+1)$-d SU(N) quantum link models reduce to ordinary 4-d Yang-Mills theory.
Characterization of control noise effects in optimal quantum unitary dynamics
David Hocker; Constantin Brif; Matthew D. Grace; Ashley Donovan; Tak-San Ho; Katharine Moore Tibbetts; Rebing Wu; Herschel Rabitz
2014-11-13T23:59:59.000Z
This work develops measures for quantifying the effects of field noise upon targeted unitary transformations. Robustness to noise is assessed in the framework of the quantum control landscape, which is the mapping from the control to the unitary transformation performance measure (quantum gate fidelity). Within that framework, a new geometric interpretation of stochastic noise effects naturally arises, where more robust optimal controls are associated with regions of small overlap between landscape curvature and the noise correlation function. Numerical simulations of this overlap in the context of quantum information processing reveal distinct noise spectral regimes that better support robust control solutions. This perspective shows the dual importance of both noise statistics and the control form for robustness, thereby opening up new avenues of investigation on how to mitigate noise effects in quantum systems.
J. E. Avron; A. Elgart; G. M. Graf; L. Sadun
2001-07-12T23:59:59.000Z
We study adiabatic quantum pumps on time scales that are short relative to the cycle of the pump. In this regime the pump is characterized by the matrix of energy shift which we introduce as the dual to Wigner's time delay. The energy shift determines the charge transport, the dissipation, the noise and the entropy production. We prove a general lower bound on dissipation in a quantum channel and define optimal pumps as those that saturate the bound. We give a geometric characterization of optimal pumps and show that they are noiseless and transport integral charge in a cycle. Finally we discuss an example of an optimal pump related to the Hall effect.
TRINITY HALL Trinity Hall, Dartry Road, Dublin 6,
O'Mahony, Donal E.
TRINITY HALL Trinity Hall, Dartry Road, Dublin 6, Ireland. Tel +353-1-4971772 E-Mail: trinity.hall@tcd.ie & warden@tcd.ie www.wardentrinityhall.tcdlife.ie/ RESIDENTS HANDBOOK 2010/2011 TRINITY HALL Students are advised to read this information in conjunction with the Conditions of Occupancy Trinity Hall 2010
Quantum effects after decoherence in a quenched phase transition
Nuno D. Antunes; Fernando C. Lombardo; Diana Monteoliva
2001-10-30T23:59:59.000Z
We study a quantum mechanical toy model that mimics some features of a quenched phase transition. Both by virtue of a time-dependent Hamiltonian or by changing the temperature of the bath we are able to show that even after classicalization has been reached, the system may display quantum behaviour again. We explain this behaviour in terms of simple non-linear analysis and estimate relevant time scales that match the results of numerical simulations of the master-equation. This opens new possibilities both in the study of quantum effects in non-equilibrium phase transitions and in general time-dependent problems where quantum effects may be relevant even after decoherence has been completed.
Exchange effects in magnetized quantum plasmas
Trukhanova, Mariya Iv
2015-01-01T23:59:59.000Z
We apply the many-particle quantum hydrodynamics including the Coulomb exchange interaction to magnetized quantum plasmas. We consider a number of wave phenomenon under influence of the Coulomb exchange interaction. Since the Coulomb exchange interaction affects longitudinal and transverse-longitudinal waves we focus our attention to the Langmuir waves, Trivelpiece-Gould waves, ion-acoustic waves in non-isothermal magnetized plasmas, the dispersion of the longitudinal low-frequency ion-acoustic waves and low-frequencies electromagnetic waves at $T_{e}\\gg T_{i}$ . We obtained the numerical simulation of the dispersion properties of different types of waves.
An Equation of Motion with Quantum Effect in Spacetime
Jyh-Yang Wu
2009-05-26T23:59:59.000Z
In this paper, we shall present a new equation of motion with Quantum effect in spacetime. To do so, we propose a classical-quantum duality. We also generalize the Schordinger equation to the spacetime and obtain a relativistic wave equation. This will lead a generalization of Einstein's formula $E=m_0c^2$ in the spacetime. In general, we have $E=m_0c^2 + \\frac{\\hbar^2}{12m_0}R$ in a spacetime.
Quantum Coherence Effects in Novel Quantum Optical Systems
Sete, Eyob Alebachew
2012-10-19T23:59:59.000Z
. . . . . . . . . . . . . . . . . . . . . 50 b. N atoms: R #29; ? . . . . . . . . . . . . . . . . . . 52 3. A delta function ingression . . . . . . . . . . . . . . . 53 C. The effect of virtual processes on single photon Dicke superradiance... qubits . . . . . . . 73 1. Initial pure state . . . . . . . . . . . . . . . . . . . . . 73 2. Initial mixed state . . . . . . . . . . . . . . . . . . . . 79 E. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 V ENTANGLEMENT OF TWO...
Polymer quantum effects on compact stars models
Guillermo Chacon-Acosta; Hector Hernandez-Hernandez
2014-08-05T23:59:59.000Z
In this work we study a completely degenerated fermion gas at zero temperature within a semiclassical approximation for the Hamiltonian arising in polymer quantum mechanics. Polymer quantum systems are quantum mechanical models quantized in a similar way as in loop quantum gravity that allow the study of the discreteness of space and other features of the loop quantization in a simplified way. We obtain the polymer modified thermodynamical properties noticing that the corresponding Fermi energy is exactly the same as if one directly polymerizes the momentum $p_F$. We also obtain the corresponding expansion of thermodynamical variables for small values of the polymer length scale $\\lambda$. With this results we study a simple model of a compact object where the gravitational collapse is supported by electron degeneracy pressure. We find polymer corrections to the mass of the star. When compared with typical measurements of the mass of white dwarfs we obtain a bound on the polymer length of $\\lambda^2\\lesssim 10^{-26}m^2$.
Quantum origin of an anomalous isotope effect in ozone formation
Reid, Scott A.
Quantum origin of an anomalous isotope effect in ozone formation D. Babikov *, B.K. Kendrick, R mechanical calculations of the ðJ ¼ 0Þ energies and lifetimes of the metastable states of ozone on a new effect in the reaction that forms ozone because of their role in the energy transfer mechanism, in which
Quantum Electrodynamical Effects in Dusty Plasmas
M. Marklund; L. Stenflo; P. K. Shukla; G. Brodin
2005-05-31T23:59:59.000Z
A new nonlinear electromagnetic wave mode in a magnetized dusty plasma is predicted. Its existence depends on the interaction of an intense circularly polarized electromagnetic wave with a dusty plasma, where quantum electrodynamical photon-photon scattering is taken into account. Specifically, we consider a dusty electron-positron-ion plasma, and show that the propagation of the new mode is admitted. It could be of significance for the physics of supernova remnants and in neutron star formation.
Bogyo, Matthew
Gardens Braun Music Center The Knoll Bechtel International Center Post Office Clubhouse Old Union 590 500 Truck Hse. Clock Tower Owen Bolivar House Haas Center Galvez Modular Sweet Hall Bookstore Law School. Hoover Tower Cummings Art Art Gallery Manzanita Dining Commons Burnham Pavilion Ford Center Montag Hall
TRINITY HALL PUBLICATION SCHEME
Lasenby, Joan
TRINITY HALL PUBLICATION SCHEME PART 1 INTRODUCTION 1. Legal requirement 1.1 Adopting a publication and whether or not charges will be made. 3. The `model' publication scheme for higher education 3.1 Trinity and is committed to publishing the information it describes. 4. Who we are 4.1 Trinity Hall is a college within
Instanton effects and quantum spectral curves
Johan Kallen; Marcos Marino
2014-04-16T23:59:59.000Z
We study a spectral problem associated to the quantization of a spectral curve arising in local mirror symmetry. The perturbative WKB quantization condition is determined by the quantum periods, or equivalently by the refined topological string in the Nekrasov-Shatashvili (NS) limit. We show that the information encoded in the quantum periods is radically insufficient to determine the spectrum: there is an infinite series of instanton corrections, which are non-perturbative in \\hbar, and lead to an exact WKB quantization condition. Moreover, we conjecture the precise form of the instanton corrections: they are determined by the standard or un-refined topological string free energy, and we test our conjecture successfully against numerical calculations of the spectrum. This suggests that the non-perturbative sector of the NS refined topological string contains information about the standard topological string. As an application of the WKB quantization condition, we explain some recent observations relating membrane instanton corrections in ABJM theory to the refined topological string.
Macroscopic quantum tunneling and the 'cosmic' Josephson effect
Barone, A. [Dipartimento di Scienze Fisiche, Universita di Napoli 'Federico II', CNR-SPIN, Piazzale Tecchio 21, 80125 Napoli (Italy); Gasperini, M. [Dipartimento di Fisica, Universita di Bari, Via G. Amendola 173, 70126 Bari (Italy); INFN, Sezione di Bari, Bari (Italy); Rotoli, G. [Dipartimento di Ingegneria dell'Informazione, Seconda Universita di Napoli (SUN), Via Roma 29, 81031 Aversa (CE) (Italy)
2010-10-15T23:59:59.000Z
We discuss the possible influence of a cosmic magnetic field on the macroscopic quantum tunneling process associated, in a cosmological context, to the decay of the 'false vacuum'. We find a close analogy with the effects of an external magnetic field applied to a Josephson junction in the context of low-temperature/high-temperature superconducting devices.
Effects of Quantum Confinement on the Doping Limit of Semiconductor
Wu, Junqiao
Effects of Quantum Confinement on the Doping Limit of Semiconductor Nanowires D. R. Khanal,, Joanne concentrations in semiconductor nanowires. Our calculations are based on the amphoteric defect model, which describes the thermodynamic doping limit in semiconductors in terms of the compensation of external dopants
Dalton, Mark M.
2014-02-01T23:59:59.000Z
Report over the experimental activities in Hall A at Thomas Jefferson National Accelerator Facility during 2013.
Tunneling in Polymer Quantization and the Quantum Zeno Effect
Durmus Ali Demir; Ozan Sargin
2014-09-25T23:59:59.000Z
As an application of the polymer quantization scheme, in this work we investigate the one dimensional quantum mechanical tunneling phenomenon from the perspective of polymer representation of a non-relativistic point particle and derive the transmission and reflection coefficients. Since any tunneling phenomenon inevitably evokes a tunneling time we attempt an analytical calculation of tunneling times by defining an operator well suited in discrete spatial geometry. The results that we come up with hint at appearance of the Quantum Zeno Effect in polymer framework.
Quantum corrections to spin effects in general relativity
G. G. Kirilin
2005-07-16T23:59:59.000Z
Quantum power corrections to the gravitational spin-orbit and spin-spin interactions, as well as to the Lense-Thirring effect, were found for particles of spin 1/2. These corrections arise from diagrams of second order in Newton gravitational constant G with two massless particles in the unitary cut in the t-channel. The corrections obtained differ from the previous calculation of the corrections to spin effects for rotating compound bodies with spinless constituents.
Effective time-independent analysis for quantum kicked systems
Jayendra N. Bandyopadhyay; Tapomoy Guha Sarkar
2014-09-04T23:59:59.000Z
We present a mapping of potentially chaotic time-dependent quantum kicked systems to an equivalent effective time-independent scenario, whereby the system is rendered integrable. The time-evolution is factorized into an initial kick, followed by an evolution dictated by a time-independent Hamiltonian and a final kick. This method is applied to the kicked top model. The effective time-independent Hamiltonian thus obtained, does not suffer from spurious divergences encountered if the traditional Baker-Cambell-Hausdorff treatment is used. The quasienergy spectrum of the Floquet operator is found to be in excellent agreement with the energy levels of the effective Hamiltonian for a wide range of system parameters. The density of states for the effective system exhibits sharp peak-like features, pointing towards quantum criticality. The dynamics in the classical limit of the integrable effective Hamiltonian shows remarkable agreement with the non-integrable map corresponding to the actual time-dependent system in the non-chaotic regime. This suggests that the effective Hamiltonian serves as a substitute for the actual system in the non-chaotic regime at both the quantum and classical level.
Broader source: Energy.gov [DOE]
Joint statement providing interim policy on processing proposals for leasing DOE real property using the authority in 42 U.S.C. 7256, commonly referred to as the "Hall Amendment."
Growing quantum states with topological order
Letscher, Fabian; Fleischhauer, Michael
2015-01-01T23:59:59.000Z
We discuss a protocol for growing states with topological order in interacting many-body systems using a sequence of flux quanta and particle insertion. We first consider a simple toy model, the superlattice Bose Hubbard model, to explain all required ingredients. Our protocol is then applied to fractional quantum Hall systems in both, continuum and lattice. We investigate in particular how the fidelity, with which a topologically ordered state can be grown, scales with increasing particle number N. For small systems exact diagonalization methods are used. To treat large systems with many particles, we introduce an effective model based on the composite fermion description of the fractional quantum Hall effect. This model also allows to take into account the effects of dispersive bands and edges in the system, which will be discussed in detail.
Relativistic Doppler effect in quantum communication
Asher Peres; Daniel R. Terno
2003-04-06T23:59:59.000Z
When an electromagnetic signal propagates in vacuo, a polarization detector cannot be rigorously perpendicular to the wave vector because of diffraction effects. The vacuum behaves as a noisy channel, even if the detectors are perfect. The ``noise'' can however be reduced and nearly cancelled by a relative motion of the observer toward the source. The standard definition of a reduced density matrix fails for photon polarization, because the transversality condition behaves like a superselection rule. We can however define an effective reduced density matrix which corresponds to a restricted class of positive operator-valued measures. There are no pure photon qubits, and no exactly orthogonal qubit states.
Vacuum state truncation via the quantum Zeno effect
Tae-Gon Noh
2012-08-22T23:59:59.000Z
In the context of quantum state engineering we analyze the effect of observation on nonlinear optical $n$-photon Fock state generation. We show that it is possible to truncate the vacuum component from an arbitrary photon number superposition without modifying its remaining parts. In the course of the full dynamical analysis of the effect of observation, it is also found that the Zeno and the anti-Zeno effects repeat periodically. We discuss the close relationship between vacuum state truncation and so-called "interaction-free" measurement.
The Monty Hall Problem Richard D. Gill
Gill, Richard D.
the Monty Hall problem is often called the Monty Hall para- dox. The key to accepting and understanding
Adding quantum effects to the semi-classical molecular dynamics simulations
Yang, Siyang
2011-01-01T23:59:59.000Z
Simulating the molecular dynamics (MD) using classical or semi-classical trajectories provides important details for the understanding of many chemical reactions, protein folding, drug design, and solvation effects. MD simulations using trajectories have achieved great successes in the computer simulations of various systems, but it is difficult to incorporate quantum effects in a robust way. Therefore, improving quantum wavepacket dynamics and incorporating nonadiabatic transitions and quantum effects into classical and semi-classical molecular dynamics is critical as well as challenging. In this paper, we present a MD scheme in which a new set of equations of motion (EOM) are proposed to effectively propagate nuclear trajectories while conserving quantum mechanical energy which is critical for describing quantum effects like tunneling. The new quantum EOM is tested on a one-state one-dimensional and a two-state two-dimensional model nonadiabatic systems. The global quantum force experienced by each trajecto...
Quantum effects with an X-ray free electron laser
C. D. Roberts; S. M. Schmidt; D. V. Vinnik
2002-06-03T23:59:59.000Z
A quantum kinetic equation coupled with Maxwell's equation is used to estimate the laser power required at an XFEL facility to expose intrinsically quantum effects in the process of QED vacuum decay via spontaneous pair production. A 9 TW-peak XFEL laser with photon energy 8.3 keV could be sufficient to initiate particle accumulation and the consequent formation of a plasma of spontaneously produced pairs. The evolution of the particle number in the plasma will exhibit non-Markovian aspects of the strong-field pair production process and the plasma's internal currents will generate an electric field whose interference with that of the laser leads to plasma oscillations.
Effect of quantum nuclear motion on hydrogen bonding
McKenzie, Ross H., E-mail: r.mckenzie@uq.edu.au; Bekker, Christiaan [School of Mathematics and Physics, University of Queensland, Brisbane 4072 (Australia)] [School of Mathematics and Physics, University of Queensland, Brisbane 4072 (Australia); Athokpam, Bijyalaxmi; Ramesh, Sai G. [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 (India)] [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 (India)
2014-05-07T23:59:59.000Z
This work considers how the properties of hydrogen bonded complexes, X–H?Y, are modified by the quantum motion of the shared proton. Using a simple two-diabatic state model Hamiltonian, the analysis of the symmetric case, where the donor (X) and acceptor (Y) have the same proton affinity, is carried out. For quantitative comparisons, a parametrization specific to the O–H?O complexes is used. The vibrational energy levels of the one-dimensional ground state adiabatic potential of the model are used to make quantitative comparisons with a vast body of condensed phase data, spanning a donor-acceptor separation (R) range of about 2.4 ? 3.0 Å, i.e., from strong to weak hydrogen bonds. The position of the proton (which determines the X–H bond length) and its longitudinal vibrational frequency, along with the isotope effects in both are described quantitatively. An analysis of the secondary geometric isotope effect, using a simple extension of the two-state model, yields an improved agreement of the predicted variation with R of frequency isotope effects. The role of bending modes is also considered: their quantum effects compete with those of the stretching mode for weak to moderate H-bond strengths. In spite of the economy in the parametrization of the model used, it offers key insights into the defining features of H-bonds, and semi-quantitatively captures several trends.
Wang, Daw-Wei
Effect of Quantum Fluctuations on the Dipolar Motion of Bose-Einstein Condensates in Optical of condensate atoms in one-dimensional optical lattices and harmonic magnetic traps including quantum is reduced, on the contrary, strong quantum fluctuations lead to finite damping of condensate oscillations
Madami, M; Moriyama, T; Tanaka, K; Siracusano, G; Carpentieri, M; Finocchio, G; Tacchi, S; Ono, T; Carlotti, G
2015-01-01T23:59:59.000Z
We employed micro-focused Brillouin light scattering to study the amplification of the thermal spin wave eigenmodes by means of a pure spin current, generated by the spin-Hall effect, in a transversely magnetized Pt(4nm)/NiFe(4nm)/SiO2(5nm) layered nanowire with lateral dimensions 500x2750 nm2. The frequency and the cross section of both the center (fundamental) and the edge spin wave modes have been measured as a function of the intensity of the injected dc electric current. The frequency of both modes exhibits a clear redshift while their cross section is greatly enhanced on increasing the intensity of the injected dc. A threshold-like behavior is observed for a value of the injected dc of 2.8 mA. Interestingly an additional mode, localized in the central part of the nanowire, appears at higher frequency on increasing the intensity of the injected dc above the threshold value. Micromagnetic simulations were used to quantitatively reproduce the experimental results and to investigate the complex non-linear d...
Effective quantum equations for the semiclassical description of the Hydrogen atom
Guillermo Chacón-Acosta; Héctor H. Hernández
2012-03-22T23:59:59.000Z
We study the Hydrogen atom as a quantum mechanical system with a Coulomb like potential, with a semiclassical approach based on an effective description of quantum mechanics. This treatment allows us to describe the quantum state of the system as a system of infinite many classical equations for expectation values of configuration variables, their moments and quantum dispersions. It also provides a semiclassical description of the orbits and the evolution of observables and spreadings and their back-reaction on the evolution.
Effect of phase transition on quantum transport in group-IV two-dimensional U-shape device
Sadi, Mohammad Abdullah; Gupta, Gaurav, E-mail: a0089293@nus.edu.sg; Liang, Gengchiau [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)
2014-10-21T23:59:59.000Z
The effect of phase-transition from the quantum-spin-hall to the band-insulator phase on the transport through a three-terminal U-shape spin-separator has been computationally investigated via non-equilibrium green function formalism. Two-dimensional group-IV elements have been comprehensively appraised as the device material. The device separates the unpolarized current injected at the source-terminal into nearly 100% spin-polarized currents of the opposite polarities at the two drain terminals. The phase-transition activated by the electric-field orthogonal to the device is shown to extensively influence the current magnitude and its spin-polarization, and the effect is stronger for materials with smaller intrinsic spin-orbit coupling. Moreover, the device length and the area under field are shown to critically affect the device characteristics on phase change. It is shown that the same device can be operated as a spin-filter by inducing phase-transition selectively in the channel. The results are important for designing spin-devices from Group-IV monolayers.
Housing services Zinfandel Hall
Ravikumar, B.
Housing services Zinfandel Hall (707) 664-2541 Fax: (707) 664-4158 e-mail: ssu.housing@sonoma.edu www.sonoma.edu/housing On-Campus Housing The Residential Community provides comfortable, convenient cam- pus housing for 3,000 single students. The Community is a unique mix of nontraditional resident
Quantum effective potential, electron transport and conformons in biopolymers
Rossen Dandoloff; Radha Balakrishnan
2005-05-29T23:59:59.000Z
In the Kirchhoff model of a biopolymer, conformation dynamics can be described in terms of solitary waves, for certain special cross-section asymmetries. Applying this to the problem of electron transport, we show that the quantum effective potential arising due to the bends and twists of the polymer enables us to formalize and quantify the concept of a {\\it conformon} that has been hypothesized in biology. Its connection to the soliton solution of the cubic nonlinear Schr\\"{o}dinger equation emerges in a natural fashion.
Semianalytical quantum model for graphene field-effect transistors
Pugnaghi, Claudio; Grassi, Roberto, E-mail: roberto.grassi@unibo.it; Gnudi, Antonio; Di Lecce, Valerio; Gnani, Elena; Reggiani, Susanna; Baccarani, Giorgio [ARCES and DEI, University of Bologna, Viale Risorgimento 2, 40136 Bologna (Italy)
2014-09-21T23:59:59.000Z
We develop a semianalytical model for monolayer graphene field-effect transistors in the ballistic limit. Two types of devices are considered: in the first device, the source and drain regions are doped by charge transfer with Schottky contacts, while, in the second device, the source and drain regions are doped electrostatically by a back gate. The model captures two important effects that influence the operation of both devices: (i) the finite density of states in the source and drain regions, which limits the number of states available for transport and can be responsible for negative output differential resistance effects, and (ii) quantum tunneling across the potential steps at the source-channel and drain-channel interfaces. By comparison with a self-consistent non-equilibrium Green's function solver, we show that our model provides very accurate results for both types of devices, in the bias region of quasi-saturation as well as in that of negative differential resistance.
On Quantum Coherence Effects in Photo and Solar Cells
Kimberly Chapin; Konstantin Dorfman; Anatoly Svidzinsky; Marlan Scully
2011-02-01T23:59:59.000Z
We show that quantum coherence can increase the quantum efficiency of various thermodynamic systems. For example, we can enhance the quantum efficiency for a quantum dot photocell, a laser based solar cell and the photo-Carnot quantum heat engine. Our results are fully consistent with the laws of thermodynamics contrary to comments found in the paper of A.P. Kirk, Phys. Rev. Lett. 106, 048703 (2011).
Quantum Hall Effect near the Charge Neutrality Point in a Two-Dimensional Electron-Hole System
Gusev, Guennady
. Gusev,1 E. B. Olshanetsky,1,2 Z. D. Kvon,2 N. N. Mikhailov,2 S. A. Dvoretsky,2 and J. C. Portal3,4,5 1 of Semiconductor Physics, Novosibirsk 630090, Russia 3 LNCMI-CNRS, UPR 3228, BP 166, 38042 Grenoble Cedex 9, France
The Casimir effect: from quantum to critical fluctuations
Andrea Gambassi
2008-12-04T23:59:59.000Z
The Casimir effect in quantum electrodynamics (QED) is perhaps the best-known example of fluctuation-induced long-ranged force acting on objects (conducting plates) immersed in a fluctuating medium (quantum electromagnetic field in vacuum). A similar effect emerges in statistical physics, where the force acting, e.g., on colloidal particles immersed in a binary liquid mixture is affected by the classical thermal fluctuations occurring in the surrounding medium. The resulting Casimir-like force acquires universal features upon approaching a critical point of the medium and becomes long-ranged at criticality. In turn, this universality allows one to investigate theoretically the temperature dependence of the force via representative models and to stringently test the corresponding predictions in experiments. In contrast to QED, the Casimir force resulting from critical fluctuations can be easily tuned with respect to strength and sign by surface treatments and temperature control. We present some recent advances in the theoretical study of the universal properties of the critical Casimir force arising in thin films. The corresponding predictions compare very well with the experimental results obtained for wetting layers of various fluids. We discuss how the Casimir force between a colloidal particle and a planar wall immersed in a binary liquid mixture has been measured with femto-Newton accuracy, comparing these experimental results with the corresponding theoretical predictions.
Nonequilibrium phonon effects in midinfrared quantum cascade lasers
Shi, Y. B., E-mail: yshi9@wisc.edu; Knezevic, I., E-mail: knezevic@engr.wisc.edu [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706-1691 (United States)
2014-09-28T23:59:59.000Z
We investigate the effects of nonequilibrium phonon dynamics on the operation of a GaAs-based midinfrared quantum cascade laser over a range of temperatures (77–300?K) via a coupled ensemble Monte Carlo simulation of electron and optical-phonon systems. Nonequilibrium phonon effects are shown to be important below 200?K. At low temperatures, nonequilibrium phonons enhance injection selectivity and efficiency by drastically increasing the rate of interstage electron scattering from the lowest injector state to the next-stage upper lasing level via optical-phonon absorption. As a result, the current density and modal gain at a given field are higher and the threshold current density lower and considerably closer to experiment than results obtained with thermal phonons. By amplifying phonon absorption, nonequilibrium phonons also hinder electron energy relaxation and lead to elevated electronic temperatures.
The trouble with orbits: the Stark effect in the old and the new quantum theory
Anthony Duncan; Michel Janssen
2014-04-21T23:59:59.000Z
The old quantum theory and Schr\\"odinger's wave mechanics (and other forms of quantum mechanics) give the same results for the line splittings in the first-order Stark effect in hydrogen, the leading terms in the splitting of the spectral lines emitted by a hydrogen atom in an external electric field. We examine the account of the effect in the old quantum theory, which was hailed as a major success of that theory, from the point of view of wave mechanics. First, we show how the new quantum mechanics solves a fundamental problem one runs into in the old quantum theory with the Stark effect. It turns out that, even without an external field, it depends on the coordinates in which the quantum conditions are imposed which electron orbits are allowed in a hydrogen atom. The allowed energy levels and hence the line splittings are independent of the coordinates used but the size and eccentricity of the orbits are not. In the new quantum theory, this worrisome non-uniqueness of orbits turns into the perfectly innocuous non-uniqueness of bases in Hilbert space. Second, we review how the so-called WKB (Wentzel-Kramers-Brillouin) approximation method for solving the Schr\\"odinger equation reproduces the quantum conditions of the old quantum theory amended by some additional half-integer terms. These extra terms remove the need for some arbitrary extra restrictions on the allowed orbits that the old quantum theory required over and above the basic quantum conditions
TRINITY HALL ACCOUNTS FOR THE YEAR ENDED
Talbot, James P.
TRINITY HALL CAMBRIDGE ACCOUNTS FOR THE YEAR ENDED 30 June 2011 #12;TRINITY HALL Index Balance Sheet 19 Cash Flow Statement 20 - 32 Notes to the Accounts #12;TRINITY HALL Governing Body;Status Trinity Hall, or The Master, Fellows and Scholars of the College or Hall of the Holy Trinity
Cylindrical geometry hall thruster
Raitses, Yevgeny (Princeton, NJ); Fisch, Nathaniel J. (Princeton, NJ)
2002-01-01T23:59:59.000Z
An apparatus and method for thrusting plasma, utilizing a Hall thruster with a cylindrical geometry, wherein ions are accelerated in substantially the axial direction. The apparatus is suitable for operation at low power. It employs small size thruster components, including a ceramic channel, with the center pole piece of the conventional annular design thruster eliminated or greatly reduced. Efficient operation is accomplished through magnetic fields with a substantial radial component. The propellant gas is ionized at an optimal location in the thruster. A further improvement is accomplished by segmented electrodes, which produce localized voltage drops within the thruster at optimally prescribed locations. The apparatus differs from a conventional Hall thruster, which has an annular geometry, not well suited to scaling to small size, because the small size for an annular design has a great deal of surface area relative to the volume.
The Hall D Physics Program at JLab
Leckey, John P. [Indiana U.
2012-09-01T23:59:59.000Z
GlueX is one of the flagship experiments of the 12 GeV era at the Thomas Jefferson National Accelerator Facility (JLab). The energy of the electron accelerator at JLab is presently undergoing an upgrade from 6 GeV to 12 GeV and a 4th experimental hall (Hall D) is being added. The GlueX experimental apparatus consists of a tagged coherent bremsstrahlung photon beam incident on a liquid hydrogen target. The photoproduced mesons, which are created inside of a 2.2 T solenoid, will then pass through a pair of drift chambers and eventually deposit their energy into either of two calorimeters, depending on their respective angles. GlueX will attempt to map out the light meson spectrum and search for meson-gluon hybrids to better understand the confinement of quarks and gluons in quantum chromodynamics (QCD). There is little data on the photoproduction of light mesons and the GlueX experiment will exceed the current photoproduction data by several orders of magnitude in the first year alone. Photoproduction is specifically well suited to search for meson-gluon hybrids because in the flux tube model the production cross-sections are higher for meson-gluon hybrids from photons, with the spins of the virtual quark-antiquark pair aligned, than from other sources such as pions, with the spins of the quark-antiquark pair anti-aligned. There are also other Hall D experiments proposed to look for physics beyond the Standard Model by studying Eta rare or forbidden decay channels such as eta to two neutral pions. The 12 GeV upgrade of the JLab accelerator and the complete physics program of Hall D will be presented.
Town Hall with Secretary Moniz
Broader source: Energy.gov [DOE]
In a town hall meeting with Department staff, Energy Secretary Ernest Moniz spoke about his plans for a reorganization of the Energy Department’s management structure.
Bing Concert Hall, Under Construction
Prinz, Friedrich B.
Freidenrich Center, Under Construction Terman Engineering Center, Demolition Frost Amphitheater Ford Plaza Hall Cowell Houses Schwab Residential Center Lyman Graduate Residences Sterling Quad Mirrielees Pearce
Why are the effective equations of loop quantum cosmology so accurate?
Carlo Rovelli; Edward Wilson-Ewing
2014-07-25T23:59:59.000Z
We point out that the relative Heisenberg uncertainty relations vanish for non-compact spaces in homogeneous loop quantum cosmology. As a consequence, for sharply peaked states quantum fluctuations in the scale factor never become important, even near the bounce point. This shows why quantum back-reaction effects remain negligible and explains the surprising accuracy of the effective equations in describing the dynamics of sharply peaked wave packets. This also underlines the fact that minisuperspace models ---where it is global variables that are quantized--- do not capture the local quantum fluctuations of the geometry.
The effect of dust size distribution on quantum dust acoustic wave
El-Labany, S. K.; El-Taibany, W. F.; Behery, E. E. [Department of Physics, Faculty of Science, Mansoura University, Damietta Branch, Damietta El-Gedida, P.O. 34517 (Egypt); El-Siragy, N. M. [Department of Physics, Faculty of Science, Tanta University, Tanta, P.O. 31527 (Egypt)
2009-09-15T23:59:59.000Z
Based on the quantum hydrodynamics theory, a proposed model for quantum dust acoustic waves (QDAWs) is presented including the dust size distribution (DSD) effect. A quantum version of Zakharov-Kuznetsov equation is derived adequate for describing QDAWs. Two different DSD functions are applied. The relevance of the wave velocity, amplitude, and width to the DSD is investigated numerically. The quantum effect changes only the soliton width. A brief conclusion is presented to the current findings and their relevance to astrophysics data is also discussed.
Quantum fluctuations and isotope effects in ab initio descriptions of water
Lu Wang; Michele Ceriotti; Thomas E. Markland
2014-06-24T23:59:59.000Z
Nuclear quantum effects, such as zero-point energy and tunneling, cause significant changes to the structure and dynamics of hydrogen bonded systems such as liquid water. However, due to the current inability to simulate liquid water using an exact description of its electronic structure, the interplay between nuclear and electronic quantum effects remains unclear. Here we use simulations that incorporate the quantum mechanical nature of both the nuclei and electrons to provide a fully ab initio determination of the particle quantum kinetic energies, free energy change upon exchanging hydrogen for deuterium and the isotope fractionation ratio in water. These properties, which selectively probe the quantum nature of the nuclear degrees of freedom, allow us to make direct comparison to recent experiments and elucidate how electronic exchange and correlation and nuclear quantum fluctuations determine the structure of the hydrogen bond in water.
K-7109Agnew Hall M-2204Air Conditioning Plant
Buehrer, R. Michael
Building] K-4171Burchard Hall L-4176Burruss Hall L-637Campbell Hall - East Wing L-636Campbell Hall - Main Center at Donaldson Brown L-9124Greenhouse Q-10 241Grounds Building (Central Stores) J-4 158Hahn Hall
Broader source: Energy.gov (indexed) [DOE]
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742Energy China 2015ofDepartment of Energy MicrosoftVOLUMEWORKFORCE DIVERSITY TOWN HALL DECEMBER
Broader source: Energy.gov [DOE]
I and my family own land in Ashfield next to the proposed Kinder Morgan/Tennessee Pipeline route. We are opposed to the pipeline for a variety of reasons, including the highly questionable need for the proposed commodity increase and the inevitable damage to the environment and communities along the proposed route. Addison Hall for the Hall Family Trust.
Rhodes Hall Ross Heart Hospital
Howat, Ian M.
Emergency 315 315 26 Rhodes Hall Ross Heart Hospital James Cancer Hospital Martha Morehouse.m. James Cancer Hospital 7:10 a.m. Rhodes Hall 7:13 a.m. Ross Heart Hospital 7:15 a.m. Martha Morehouse
Utah, University of
to monitor this time evolution using the measurement results. This effect is shown to be equivalent the statistics of the results of a series of measurements performed on a single system, with no time evolution of measurements are independent of the measurement results. Therefore it was also suggested that the quantum Zeno
Quantum fluctuations and isotope effects in ab initio descriptions of water
Wang, Lu; Markland, Thomas E., E-mail: tmarkland@stanford.edu [Department of Chemistry, Stanford University, 333 Campus Drive, Stanford, California 94305 (United States); Ceriotti, Michele, E-mail: michele.ceriotti@epfl.ch [Laboratory of Computational Science and Modeling, École Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland)
2014-09-14T23:59:59.000Z
Isotope substitution is extensively used to investigate the microscopic behavior of hydrogen bonded systems such as liquid water. The changes in structure and stability of these systems upon isotope substitution arise entirely from the quantum mechanical nature of the nuclei. Here, we provide a fully ab initio determination of the isotope exchange free energy and fractionation ratio of hydrogen and deuterium in water treating exactly nuclear quantum effects and explicitly modeling the quantum nature of the electrons. This allows us to assess how quantum effects in water manifest as isotope effects, and unravel how the interplay between electronic exchange and correlation and nuclear quantum fluctuations determine the structure of the hydrogen bond in water.
Cosmological fluctuations: Comparing Quantum and Classical Statistical and Stringy Effects
de Alwis, S P
2015-01-01T23:59:59.000Z
The theory of cosmological fluctuations assumes that the pre-inflationary state of the universe was the quantum vacuum of a scalar field(s) coupled to gravity. The observed cosmic microwave background fluctuations are then interpreted as quantum fluctuations. Here we consider alternate interpretations of the classic calculations of scalar and tensor power spectra by replacing the quantum vacuum with a classical statistical distribution, and suggest a way of distinguishing the quantum from the classical alternatives. The possibility that the latter is governed by a fundamental length scale as in string theory is also explored.
A quantitative account of quantum effects in liquid water. |...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
report quantum statistical mechanical simulations of liquid water with the TTM2.1-F flexible, polarizable interaction potential for water. The potential is the first...
Le Roy, Robert J.
February 1998 Comparisons of classical and quantum Monte Carlo simulation of SF6 Ar n and SF6 Ne n clusters are used to examine whether certain novel types of behavior seen in classical simulations of SF6 Ar n and SF6 Kr n persist when quantum effects are taken into account. For mixed clusters formed
Acceleration of positrons by a relativistic electron beam in the presence of quantum effects
Niknam, A. R. [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of)] [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of); Aki, H.; Khorashadizadeh, S. M. [Physics Department, Birjand University, Birjand (Iran, Islamic Republic of)] [Physics Department, Birjand University, Birjand (Iran, Islamic Republic of)
2013-09-15T23:59:59.000Z
Using the quantum magnetohydrodynamic model and obtaining the dispersion relation of the Cherenkov and cyclotron waves, the acceleration of positrons by a relativistic electron beam is investigated. The Cherenkov and cyclotron acceleration mechanisms of positrons are compared together. It is shown that growth rate and, therefore, the acceleration of positrons can be increased in the presence of quantum effects.
DARK MATTER AND DARK ENERGY AS EFFECTS OF QUANTUM GRAVITY Max I. Fomitchev1
Giles, C. Lee
DARK MATTER AND DARK ENERGY AS EFFECTS OF QUANTUM GRAVITY Max I. Fomitchev1 Submitted March 12th of high matter density expected in the early Universe I show that primordial inflation and dark energy (i , 2004 ABSTRACT I present a theory of quantum gravity based on the principle of gravitational energy
Progress Toward Observing Quantum Effects in an Optomechanical System in Cryogenics
Harris, Jack
, placed at 400 mK inside a 3 He fridge. The major goals of this research are: laser cooling the 261 kAbstract Progress Toward Observing Quantum Effects in an Optomechanical System in Cryogenics Cheng Yang 2011 Quantum optomechanical systems use radiation pressure of light to couple the optical field
All-Optical Switching Using the Quantum Zeno Effect and Two-Photon Absorption
B. C. Jacobs; J. D. Franson
2009-05-08T23:59:59.000Z
We have previously shown that the quantum Zeno effect can be used to implement quantum logic gates for quantum computing applications, where the Zeno effect was produced using a strong two-photon absorbing medium. Here we show that the Zeno effect can also be used to implement classical logic gates whose inputs and outputs are high-intensity fields (coherent states). The operation of the devices can be understood using a quasi-static analysis, and their switching times are calculated using a dynamic approach. The two-photon absorption coefficient of rubidium vapor is shown to allow operation of these devices at relatively low power levels.
Quantum size effects and transport phenomena in PbSe quantum wells and PbSe/EuS superlattices
Rogacheva, E. I.; Nashchekina, O. N.; Ol'khovskaya, S. I.; Sipatov, A. Yu. [National technical university Kharkov polytechnic institute, 21 Frunze St., Kharkov, 61002 (Ukraine); Dresselhaus, M. S. [Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge MA 02139 (United States)
2013-12-04T23:59:59.000Z
It is established that the room-temperature dependences of transport properties on the total thickness of PbSe layers d in PbSe/EuS superlattices exhibit an oscillatory behavior. It is shown that the oscillation period ?d practically coincides with the period of the thickness oscillations observed earlier in single PbSe/EuS quantum well. The non-monotonic character of these dependences is attributed to quantum size effects. The theoretically estimated and experimentally determined ?d values are in good agreement.
Peter Diener; Brajesh Gupt; Parampreet Singh
2014-05-16T23:59:59.000Z
A key result of isotropic loop quantum cosmology is the existence of a quantum bounce which occurs when the energy density of the matter field approaches a universal maximum close to the Planck density. Though the bounce has been exhibited in various matter models, due to severe computational challenges some important questions have so far remained unaddressed. These include the demonstration of the bounce for widely spread states, its detailed properties for the states when matter field probes regions close to the Planck volume and the reliability of the continuum effective spacetime description in general. In this manuscript we rigorously answer these questions using the Chimera numerical scheme for the isotropic spatially flat model sourced with a massless scalar field. We show that as expected from an exactly solvable model, the quantum bounce is a generic feature of states even with a very wide spread, and for those which bounce much closer to the Planck volume. We perform a detailed analysis of the departures from the effective description and find some expected, and some surprising results. At a coarse level of description, the effective dynamics can be regarded as a good approximation to the underlying quantum dynamics unless the states correspond to small scalar field momenta, in which case they bounce closer to the Planck volume, or are very widely spread. Quantifying the amount of discrepancy between the quantum and the effective dynamics, we find that the departure between them depends in a subtle and non-monotonic way on the field momentum and different fluctuations. Interestingly, the departures are generically found to be such that the effective dynamics overestimates the spacetime curvature, and underestimates the volume at the bounce.
Environment-Induced Effects on Quantum Chaos: Decoherence, Delocalization and Irreversibility
B. L. Hu; K. Shiokawa
1995-01-13T23:59:59.000Z
Decoherence in quantum systems which are classically chaotic is studied. It is well-known that a classically chaotic system when quantized loses many prominent chaotic traits. We show that interaction of the quantum system with an environment can under general circumstances quickly diminish quantum coherence and reenact some characteristic classical chaotic behavior. We use the Feynman-Vernon influence functional formalism to study the effect of an ohmic environment at high temperature on two classically-chaotic systems: The linear Arnold cat map (QCM) and the nonlinear quantum kicked rotor (QKR). Features of quantum chaos such as recurrence in QCM and diffusion suppression leading to localization in QKR are destroyed in a short time due to environment-induced decoherence. Decoherence also undermines localization and induces an apparent transition from reversible to irreversible dynamics in quantum chaotic systems.
Melnik, Roderick
Coupled electromechanical effects in wurtzite quantum dots with wetting layers in gate controlled quantifies the electromechanical effects on the band structure of wurtzite quantum dots. c Systematic study on the band structure calculations of wurtzite AlN/GaN quantum dots with wetting layers (WLs). Based
CONFERENCES | EVENTS | FINE DINING TRINITY HALL
Lasenby, Joan
CONFERENCES | EVENTS | FINE DINING #12;32 WELCOME WELCOME TO TRINITY HALL CONFERENCE AND EVENTS "If and point the way to the gardens of Trinity Hall. "HENRY JAMES 1878 Trinity Hall is the fifth oldest college from the hustle and bustle of the City, Trinity Hall has a quiet, peaceful air making it perfect
Interaction effects and quantum phase transitions in topological insulators
Varney, Christopher N. [Department of Physics, Georgetown University, Washington, DC 20057 (United States); Joint Quantum Institute and Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Sun Kai; Galitski, Victor [Joint Quantum Institute and Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Rigol, Marcos [Department of Physics, Georgetown University, Washington, DC 20057 (United States)
2010-09-15T23:59:59.000Z
We study strong correlation effects in topological insulators via the Lanczos algorithm, which we utilize to calculate the exact many-particle ground-state wave function and its topological properties. We analyze the simple, noninteracting Haldane model on a honeycomb lattice with known topological properties and demonstrate that these properties are already evident in small clusters. Next, we consider interacting fermions by introducing repulsive nearest-neighbor interactions. A first-order quantum phase transition was discovered at finite interaction strength between the topological band insulator and a topologically trivial Mott insulating phase by use of the fidelity metric and the charge-density-wave structure factor. We construct the phase diagram at T=0 as a function of the interaction strength and the complex phase for the next-nearest-neighbor hoppings. Finally, we consider the Haldane model with interacting hard-core bosons, where no evidence for a topological phase is observed. An important general conclusion of our work is that despite the intrinsic nonlocality of topological phases their key topological properties manifest themselves already in small systems and therefore can be studied numerically via exact diagonalization and observed experimentally, e.g., with trapped ions and cold atoms in optical lattices.
Quantum coherence effects in quasidegenerate two-level atomic systems
Dong Yabin; Wang Haihong; Gao Jiangrui; Zhang Junxiang [State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 (China)
2006-12-15T23:59:59.000Z
The wealth of quantum coherence effects depending on the orientation of external magnetic field, the polarization of coupling and probe lights, and the Rabi frequency of the coupling beam are studied in transition F{sub e}=2{r_reversible}F{sub g}=3 of Cs D{sub 2} line. The split of electromagnetically induced transparency (EIT) resonances on two or three resonances determined by the different combination of the polarization of interaction lights and the direction of applied magnetic fields is obtained. The shifting and widening of the EIT resonances with the strength of the magnetic field (i.e., Zeeman splitting in the upper and lower levels) and Rabi frequency of the coupling beam increasing are also discussed. It may develop into the potential application for tunable multichannel optical information storage. On the other hand, an explanation of observed asymmetry of spectra by laser frequency offset from the optical resonance is given with theoretical calculation, which is in good agreement with the experimental results.
Resonances of the confined hydrogeno¨id ion and the Dicke effect in non-relativistic quantum describes a hydrogeno¨id ion confined by its center of mass, and is used in theoretical physics to explain
Physics and modeling of an end-Hall (gridless) ion source
Oudini, N. [Universite de Toulouse, UPS, INPT, LAPLACE (Laboratoire Plasma et Conversion d'Energie), 118 route de Narbonne, F-31062 Toulouse cedex 9 (France); Hagelaar, G. J. M.; Boeuf, J.-P.; Garrrigues, L. [Universite de Toulouse, UPS, INPT, LAPLACE (Laboratoire Plasma et Conversion d'Energie), 118 route de Narbonne, F-31062 Toulouse cedex 9 (France); CNRS, LAPLACE, F-31062 Toulouse (France)
2011-04-01T23:59:59.000Z
In an end-Hall source, an ion beam is extracted from a magnetized plasma and accelerated by the plasma electric field without grids. The principle of end-Hall sources is similar to that of Hall effect thrusters (or closed-drift thrusters), but their design is optimized for processing applications (ion beam assisted deposition or substrate cleaning) rather than propulsion. The beam divergence is larger in end-Hall ion sources, and these sources can operate at low ion energies. Although end-Hall sources are commonly used in the surface processing industry, no detailed modeling of these sources is available, and their operation is quite empirical. In this paper, a self-consistent, two-dimensional, quasineutral model of an end-Hall ion source is developed and used in order to improve the understanding of the basic physics of these plasma sources and to quantify the parameters controlling the properties of the extracted ion beam.
Broader source: Energy.gov [DOE]
Secretary Steven Chu hosted an online town hall to discuss the clean energy and innovation agenda President Obama laid out in his 2011 State of the Union address. (January 26, 2011)
Quantum-mechanical description of Lense-Thirring effect for relativistic scalar particles
Alexander J. Silenko
2014-08-10T23:59:59.000Z
Exact expression for the Foldy-Wouthuysen Hamiltonian of scalar particles is used for a quantum-mechanical description of the relativistic Lense-Thirring effect. The exact evolution of the angular momentum operator in the Kerr field approximated by a spatially isotropic metric is found. The quantum-mechanical description of the full Lense-Thirring effect based on the Laplace-Runge-Lenz vector is given in the nonrelativistic and weak-field approximation. Relativistic quantum-mechanical equations for the velocity and acceleration operators are obtained. The equation for the acceleration defines the Coriolis-like and centrifugal-like accelerations and presents the quantum-mechanical description of the frame-dragging effect.
Optimization of Cylindrical Hall Thrusters
Yevgeny Raitses, Artem Smirnov, Erik Granstedt, and Nathaniel J. Fi
2007-07-24T23:59:59.000Z
The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation. __________________________________________________
Optimization of Cylindrical Hall Thrusters
Yevgeny Raitses, Artem Smirnov, Erik Granstedt, and Nathaniel J. Fisch
2007-11-27T23:59:59.000Z
The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation.
Haaren Hall North Hall WestportNew Building BMW 54th St. Annex Getting Around
Rosen, Jay
Haaren Hall North Hall WestportNew Building BMW 54th St. Annex Getting Around 4th Edition September . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BMW Â· Floor 6
Paris-Sud XI, Université de
hal-00130698,version1-13Feb2007 Electronic structure of epitaxial graphene layers on SiC: effect integer quantum Hall effects expected for isolated graphene sheets. This is the case eventhough the layer-substrate epitaxy of these films implies a strong interface bond that should induce perturbations in the graphene
Dowling, Jonathan P.
to the loss of photons caused by the inter- action between the fiber and the electromagnetic field. By frequently monitoring the presence of the photon through a quantum non-demolition (QND) measurement), and the processing is accomplished by sending the photon through a system of linear optical elements and using
Effects of quantum space time foam in the neutrino sector
H. V. Klapdor-Kleingrothaus; H. Päs; U. Sarkar
2000-07-05T23:59:59.000Z
We discuss violations of CPT and quantum mechanics due to interactions of neutrinos with space-time quantum foam. Neutrinoless double beta decay and oscillations of neutrinos from astrophysical sources (supernovae, active galactic nuclei) are analysed. It is found that the propagation distance is the crucial quantity entering any bounds on EHNS parameters. Thus, while the bounds from neutrinoless double beta decay are not significant, the data of the supernova 1987a imply a bound being several orders of magnitude more stringent than the ones known from the literature. Even more stringent limits may be obtained from the investigation of neutrino oscillations from active galactic nuclei sources, which have an impressive potential for the search of quantum foam interactions in the neutrino sector.
Real-time effective-action approach to the Anderson quantum dot
Sexty, Denes; Pawlowski, Jan
2010-01-01T23:59:59.000Z
The non-equilibrium time evolution of an Anderson quantum dot is investigated. The quantum dot is coupled between two leads forming a chemical-potential gradient. We use Kadanoff-Baym dynamic equations within a non-perturbative resummation of the s-channel bubble chains. The effect of the resummation leads to the introduction of a frequency-dependent 4-point vertex. The tunneling to the leads is taken into account exactly. The method allows the determination of the transient as well as stationary transport through the quantum dot, and results are compared with different schemes discussed in the literature (fRG, ISPI, tDMRG and QMC).
Real-time effective-action approach to the Anderson quantum dot
Denes Sexty; Thomas Gasenzer; Jan Pawlowski
2010-12-20T23:59:59.000Z
The non-equilibrium time evolution of an Anderson quantum dot is investigated. The quantum dot is coupled between two leads forming a chemical-potential gradient. We use Kadanoff-Baym dynamic equations within a non-perturbative resummation of the s-channel bubble chains. The effect of the resummation leads to the introduction of a frequency-dependent 4-point vertex. The tunneling to the leads is taken into account exactly. The method allows the determination of the transient as well as stationary transport through the quantum dot, and results are compared with different schemes discussed in the literature (fRG, ISPI, tDMRG and QMC).
Correlation effects on topological insulator
Xiong-Jun Liu; Yang Liu; Xin Liu
2010-11-24T23:59:59.000Z
The strong correlation effects on topological insulator are studied in a two-sublattice system with an onsite single-particle energy difference $\\Delta$ between two sublattices. At $\\Delta=0$, increasing the onsite interaction strength $U$ drives the transition from the quantum spin Hall insulating state to the non-topological antiferromagnetic Mott-insulating (AFMI) state. When $\\Delta$ is larger than a certain value, a topologically trivial band insulator or AFMI at small values of $U$ may change into a quantum anomalous Hall state with antiferromagnetic ordering at intermediate values of $U$. Further increasing $U$ drives the system back into the topologically trivial state of AFMI. The corresponding phenomena is observable in the solid state and cold atom systems. We also propose a scheme to realize and detect these effects in cold atom systems.
The effect of Coulomb interactions on thermoelectric properties of quantum dots
Zimbovskaya, Natalya A. [Department of Physics and Electronics, University of Puerto Rico-Humacao, CUH Station, Humacao, Puerto Rico 00791, USA and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Ruco 00931 (United States)] [Department of Physics and Electronics, University of Puerto Rico-Humacao, CUH Station, Humacao, Puerto Rico 00791, USA and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Ruco 00931 (United States)
2014-03-14T23:59:59.000Z
Thermoelectric effects in a quantum dot coupled to the source and drain charge reservoirs are explored using a nonequilibrium Green's functions formalism beyond the Hartree-Fock approximation. Thermal transport is analyzed within a linear response regime. A transition from Coulomb blockade regime to Kondo regime in thermoelectric transport through a single-level quantum dot is traced using unified approximations for the relevant Green's functions.
Physics program in Hall A at CEBAF
Saha, A.
1990-01-01T23:59:59.000Z
We present here the physics program planned for Hall A at CEBAF. It encompass exclusive as well as inclusive electromagnetic measurements requiring both high precision and accuracy. The program includes measurements of the elementary form factors of the nucleon, systematic studies of the few nucleon systems (d, {sup 3,4}He), high momentum structure of nuclei, their structure at high Q{sup 2} to look for hadronization and quark effects, spin response of nuclei via ({rvec e}, e{prime}{rvec p}) reactions and the study of nuclear pion fields.
Hendra, P. I. B., E-mail: ib.hendra@gmail.com; Rahayu, F., E-mail: ib.hendra@gmail.com; Darma, Y., E-mail: ib.hendra@gmail.com [Physical Vapor Deposition Laboratory, Physics of Material Electronics Research, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)
2014-03-24T23:59:59.000Z
Intermediate band solar cell (IBSC) has become a promising technology in increasing solar cell efficiency. In this work we compare absorption coefficient profile between InAs quantum dots with GaAs bulk. We calculate the efficiency of GaAs bulk and GaAs doped with 2, 5, and 10 nm InAs quantum dot. Effective distances in quantum dot arrangement based on electron tunneling consideration were also calculated. We presented a simple calculation method with low computing power demand. Results showed that arrangement of quantum dot InAs in GaAs can increase solar cell efficiency from 23.9 % initially up to 60.4%. The effective distance between two quantum dots was found 2 nm in order to give adequate distance to prevent electron tunneling and wave functions overlap.
UBC Video Collection / Raymond J. Hall (collector)
Handy, Todd C.
UBC Video Collection / Raymond J. Hall (collector) Compiled by Christopher Hives (2011) University / Physical Description Collector's Biographical Sketch Custodial History Scope and Content Item List (collector). - 1992-2002. 30 video recordings. Collector's Biographical Sketch Raymond Hall came to Vancouver
City Hall plazas : they're different
Hall, Kristen E. (Kristen Elizabeth)
2008-01-01T23:59:59.000Z
This essay explores the form, goals, and ideals behind city hall plazas by asking the questions: What is the difference between a city hall plaza and any other urban plaza? What are the uses intended by the city in the ...
The Monty Hall Problem Afra Zomorodian
Zomorodian, Afra
The Monty Hall Problem's origin is from the TV show, "Let's Make A Deal" hosted by Monty Hall. The statement curtain but before the curtain is lifted, the emcee lifts one of the other curtains, revealing an empty
The Monty Hall Problem Afra Zomorodian
Zomorodian, Afra
The Monty Hall Problem's origin is from the TV show, ``Let's Make A Deal'' hosted by Monty Hall have picked one curtain but before the curtain is lifted, the emcee lifts one of the other curtains
A molecular dynamics study of nuclear quantum effect on the diffusion of hydrogen in condensed phase
Nagashima, Hiroki; Tokumasu, Takashi [Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi (Japan); Tsuda, Shin-ichi [Shinshu University, 77-7 Minamibori, Nagano, Nagano (Japan); Tsuboi, Nobuyuki [Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, Kitakyushu, Fukuoka (Japan); Koshi, Mitsuo [Yokohama National University, 79-7 Tokiwadai, Hodogaya, Yokohama, Kanagawa (Japan); Hayashie, A. Koichi [AoyamaGakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa (Japan)
2014-10-06T23:59:59.000Z
In this paper, the quantum effect of hydrogen molecule on its diffusivity is analyzed using Molecular Dynamics (MD) method. The path integral centroid MD (CMD) method is applied for the reproduction method of time evolution of the molecules. The diffusion coefficient of liquid hydrogen is calculated using the Green-Kubo method. The simulation is performed at wide temperature region and the temperature dependence of the quantum effect of hydrogen molecule is addressed. The calculation results are compared with those of classical MD results. As a result, it is confirmed that the diffusivity of hydrogen molecule is changed depending on temperature by the quantum effect. It is clarified that this result can be explained that the dominant factor by quantum effect on the diffusivity of hydrogen changes from the swollening the potential to the shallowing the potential well around 30 K. Moreover, it is found that this tendency is related to the temperature dependency of the ratio of the quantum kinetic energy and classical kinetic energy.
Geometrical effects on energy transfer in disordered open quantum systems
M. Mohseni; A. Shabani; S. Lloyd; Y. Omar; H. Rabitz
2012-12-31T23:59:59.000Z
We explore various design principles for efficient excitation energy transport in complex quantum systems. We investigate energy transfer efficiency in randomly disordered geometries consisting of up to 20 chromophores to explore spatial and spectral properties of small natural/artificial Light-Harvesting Complexes (LHC). We find significant statistical correlations among highly efficient random structures with respect to ground state properties, excitonic energy gaps, multichromophoric spatial connectivity, and path strengths. These correlations can even exist beyond the optimal regime of environment-assisted quantum transport. For random configurations embedded in spatial dimensions of 30 A and 50 A, we observe that the transport efficiency saturates to its maximum value if the systems contain 7 and 14 chromophores respectively. Remarkably, these optimum values coincide with the number of chlorophylls in (Fenna-Matthews-Olson) FMO protein complex and LHC II monomers, respectively, suggesting a potential natural optimization with respect to chromophoric density.
Generalized decoding, effective channels, and simplified security proofs in quantum key distribution
Renes, Joseph M. [IAKS Prof. Beth, Arbeitsgruppe Quantum Computing, Universitaet Karlsruhe, Am Fasanengarten 5, D-76131 Karlsruhe (Germany); Quantum Information Theory Group, Institut fuer Theoretische Physik I, and Max-Planck-Forschungsgruppe, Institut fuer Optik, Information und Photonik, Universitaet Erlangen-Nuernberg, Staudtstrasse 7, D-91058 Erlangen (Germany); Grassl, Markus [IAKS Prof. Beth, Arbeitsgruppe Quantum Computing, Universitaet Karlsruhe, Am Fasanengarten 5, D-76131 Karlsruhe (Germany)
2006-08-15T23:59:59.000Z
Prepare and measure quantum key distribution protocols can be decomposed into two basic steps: delivery of the signals over a quantum channel and distillation of a secret key from the signal and measurement records by classical processing and public communication. Here we formalize the distillation process for a general protocol in a purely quantum-mechanical framework and demonstrate that it can be viewed as creating an 'effective' quantum channel between the legitimate users Alice and Bob. The process of secret key generation can then be viewed as entanglement distribution using this channel, which enables application of entanglement-based security proofs to essentially any prepare and measure protocol. To ensure secrecy of the key, Alice and Bob must be able to estimate the channel noise from errors in the key, and we further show how symmetries of the distillation process simplify this task. Applying this method, we prove the security of several key distribution protocols based on equiangular spherical codes.
Holonomic Quantum Computing Based on the Stark Effect
Bernevig, B A
2004-01-01T23:59:59.000Z
We propose a spin manipulation technique based entirely on electric fields applied to acceptor states in $p$-type semiconductors with spin-orbit coupling. While interesting in its own right, the technique can also be used to implement fault-resilient holonomic quantum computing. We explicitly compute adiabatic transformation matrix (holonomy) of the degenerate states and comment on the feasibility of the scheme as an experimental technique.
Holonomic Quantum Computing Based on the Stark Effect
B. A. Bernevig; S. C. Zhang
2004-02-23T23:59:59.000Z
We propose a spin manipulation technique based entirely on electric fields applied to acceptor states in $p$-type semiconductors with spin-orbit coupling. While interesting in its own right, the technique can also be used to implement fault-resilient holonomic quantum computing. We explicitly compute adiabatic transformation matrix (holonomy) of the degenerate states and comment on the feasibility of the scheme as an experimental technique.
Tripathi, Madhvendra Nath, E-mail: ommadhav27@gmail.com [Department of Pure and Applied Physics, Guru Ghasidas Vishwavidyalaya, Bilaspur-495009, Chhattisgarh (India)
2014-04-24T23:59:59.000Z
The paper examines the effect of spatial confinement of acoustic phonons on average group velocity and consequently the lattice thermal conductivity of a free-standing PbTe quantum well structure and their temperature dependence. The average group velocity at 100 Å decreases 30% to the bulk value and falls more rapidly on reducing the width of quantum well. Moreover, the lattice thermal conductivity of 100 Å wide PbTe quantum well with value of 0.60 W/mK shows considerable decrease of 70% compared to it’s bulk value. It is observed that the effect of reduction in well width is less pronounce as temperature increases. This appears mainly due to dominance of umklapp processes over the confinement effects.
Experimental Hall D | Jefferson Lab
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItem NotEnergy,ARMFormsGasReleaseSpeechesHall A This photo shows one of theHall D
Congreve Hall ThompsonHall Murkland Hall DeMer Ha DimondLibrary Bounce House Bounce House 13-30 31 Durham Business Association 96A Durham: It's Where U Live 164 Ecological Advocates 14 Education Crime Investigation Association 49 Hillell 167 Horsemen's Club 29 Housing 138 Improv Anonymous 13
Graduate Hall Director Office of Residential Programs
Hone, James
Page 1 Graduate Hall Director Office of Residential Programs Housing Guidelines #12;Page 2 Graduate Hall Director for Residential Programs Guidelines for Residence This document is intended for the Office of Residential Programs Graduate Hall Directors (GHDs) who obtain housing on campus as part
THalumni.net Trinity Hall's online community
Lasenby, Joan
THalumni.net Trinity Hall's online community Joining THalumni.net allows members to: · Check or location and send a private message to other Trinity Hall members. · Join the careers directory if you or loca- tion and send Trinity Hall members a private message. · Book and pay for events online and see
Nanoconstriction-based spin-Hall nano-oscillator
Demidov, V. E., E-mail: demidov@uni-muenster.de [Department of Physics and Center for Nonlinear Science, University of Muenster, Corrensstr. 2-4, 48149 Muenster (Germany); Urazhdin, S.; Zholud, A. [Department of Physics, Emory University, 400 Dowman Dr., Atlanta, Georgia 30322 (United States); Sadovnikov, A. V. [Department of Physics and Center for Nonlinear Science, University of Muenster, Corrensstr. 2-4, 48149 Muenster (Germany); Saratov State University, 83 Astrakhanskaya str., Saratov 410012 (Russian Federation); Demokritov, S. O. [Department of Physics and Center for Nonlinear Science, University of Muenster, Corrensstr. 2-4, 48149 Muenster (Germany); Institute of Metal Physics, Ural Division of RAS, Yekaterinburg 620041 (Russian Federation)
2014-10-27T23:59:59.000Z
We experimentally demonstrate magnetic nano-oscillators driven by pure spin current produced by the spin Hall effect in a bow tie-shaped nanoconstriction. These devices exhibit single-mode auto-oscillation and generate highly-coherent electronic microwave signals with a significant power and the spectral linewidth as low as 6.2?MHz at room temperature. The proposed simple and flexible device geometry is amenable to straightforward implementation of advanced spintronic structures such as chains of mutually coupled spin-Hall nano-oscillators.
Anyonic statistics and large horizon diffeomorphisms for Loop Quantum Gravity Black Holes
Andreas G. A. Pithis; Hans-Christian Ruiz Euler
2015-03-24T23:59:59.000Z
We investigate the role played by large diffeomorphisms of quantum Isolated Horizons for the statistics of LQG Black Holes by means of their relation to the braid group. To this aim the symmetries of Chern-Simons theory are recapitulated with particular regard to the aforementioned type of diffeomorphisms. For the punctured spherical horizon, these are elements of the mapping class group of $S^2$, which is almost isomorphic to a corresponding braid group on this particular manifold. The mutual exchange of quantum entities in two dimensions is achieved by the braid group, rendering the statistics anyonic. With this we argue that the quantum Isolated Horizon model of LQG based on $SU(2)_k$-Chern-Simons theory explicitly exhibits non-abelian anyonic statistics. In this way a connection to the theory behind the fractional quantum Hall effect and that of topological quantum computation is established, where non-abelian anyons play a significant role.
Anh Tuan, Duong; Shin, Yooleemi; Viet Cuong, Tran; Cho, Sunglae, E-mail: slcho@ulsan.ac.kr [Department of Physics and Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Phan, The-Long [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of)
2014-05-07T23:59:59.000Z
The Fe{sub 1?x}Ga{sub x} thin films (x?=?0.4, 0.5) have been grown on GaSb(100) substrate using molecular beam epitaxy. An epitaxial film with bcc ?-Fe crystal structure (A2) is observed in Fe{sub 0.6}Ga{sub 0.4} film, while an impure Fe{sub 3}Ga phase with DO{sub 3} structure is appeared in Fe{sub 0.5}Ga{sub 0.5} film. The saturated magnetizations at room temperature are observed to be 570?emu/cm{sup 3} and 180?emu/cm{sup 3} and the coercivities to be 170 and 364?Oe for Fe{sub 0.6}Ga{sub 0.4} and Fe{sub 0.5}Ga{sub 0.5}, respectively. A hysteresis trend in Hall resistance vs. magnetic field is observed for Fe{sub 0.5}Ga{sub 0.5} film. However, there is a weak hysteresis noticed in Fe{sub 0.4}Ga{sub 0.6} thin film.
Bing Concert Hall, Under Construction
Prinz, Friedrich B.
BioE/ChemE Building Bing Concert Hall, Under Construction Arrillaga Family Dining Commons West Campus Recreation Center, Under Construction BioE/ChemE Building, Under Construction Terman Engineering Moore Materials Rsrch. Durand David Packard Elect. Eng. Paul G. Allen Building Roble Pool Roble Modulars
Bing Concert Hall, Under Construction
Straight, Aaron
a Tresidder Union Dinkelspiel AuditoriumFaculty Club Kingscote Gardens Braun Music Center The Knoll Bechtel Meyer Library Fire Truck Hse. Clock Tower Owen Bolivar House Haas Center Galvez Modular Bookstore Crothers Memorial Encina Commons Encina HallBing Wing Lou Henry Hoover Bldg.Hoover Tower Cummings Art Art
William James Granville Stanley Hall
Maxwell, Bruce D.
William James Harvard Granville Stanley Hall Johns Hopkins James Rowland Angell Chicago Morton Leon Festinger U. of Iowa Stanley Schacther U. Of Michigan Richard Nisbett Columbia Timothy D. Wilson U. of Michigan G. Daniel Lassiter U. of Virginia Ian Handley Ohio University Max Frederick Meyer U. Of Missouri
Effectiveness of classical spin simulations for describing NMR relaxation of quantum spins
Tarek A. Elsayed; Boris V. Fine
2014-09-29T23:59:59.000Z
We investigate the limits of effectiveness of classical spin simulations for predicting free induction decays (FIDs) measured by solid-state nuclear magnetic resonance (NMR) on systems of quantum nuclear spins. The specific limits considered are associated with the range of interaction, the size of individual quantum spins and the long-time behavior of the FID signals. We compare FIDs measured or computed for lattices of quantum spins (mainly spins 1/2) with the FIDs computed for the corresponding lattices of classical spins. Several cases of excellent quantitative agreement between quantum and classical FIDs are reported along with the cases of gradually decreasing quality of the agreement. We formulate semi-empirical criteria defining the situations, when classical simulations are expected to accurately reproduce quantum FIDs. Our findings indicate that classical simulations may be a quantitatively accurate tool of first principles calculations for a broad class of macroscopic systems, where individual quantum microscopic degrees of freedom are far from the classical limit.
Iye, Yasuhiro
by around Coulomb (resonant) peaks obeying the Breit-Wigner law. On the other hand, there appeared-phase Coulomb peaks" in quantum dots. KEYWORDS: quantum dot, Fano effect, phase shift, AB effect 1. Introduction of the phase shift just at the Coulomb peaks. This was soon turned out to be a kind of artifact due to the two
Quantum Gravity effect on neutrino oscillations in a strong gravitational field
Jonathan Miller; Roman Pasechnik
2014-11-14T23:59:59.000Z
In the framework of quantum field theory, a graviton interacts locally with a quantum state having definite mass, i.e. the gravitational mass eigenstate, while a weak boson interacts with a state having definite flavor, i.e. the flavor eigenstate. An interaction of a neutrino with an energetic graviton may trigger the collapse of the neutrino to a definite mass eigenstate with probability expressed in terms of PMNS mixing matrix elements. Thus, gravitons would induce quantum decoherence of a coherent neutrino flavor state similarly to how weak bosons induce quantum decoherence of a neutrino in a definite mass state. We demonstrate that such an essentially quantum gravity effect may have strong consequences for neutrino oscillation phenomena in astrophysics due to relatively large scattering cross sections of relativistic neutrinos undergoing large-angle radiation of energetic gravitons in gravitational field of a classical massive source (i.e. the quasi-classical case of gravitational Bethe-Heitler scattering). This graviton-induced {\\em decoherence} is compared to {\\em decoherence} due to propagation in the presence of the Earth matter effect. Based on this study, we propose a new technique for the indirect detection of energetic gravitons by measuring the flavor composition of astrophysical neutrinos.
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS 1 Modeling of Terahertz Heating Effects in
Ganesan, Sashikumaar
experiments involving biological tissues. Index Terms--Far infrared, Terahertz Heating, Breast and BrainIEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS 1 Modeling of Terahertz Heating Effects in real tissues causes heating as with any other electromagnetic radiation propagation. A finite element
Effects of geometry and impurities on quantum rings in magnetic fields RID D-3014-2009
Aichinger, M.; Chin, Siu A.; Krotscheck, E.; Rasanen, E.
2006-01-01T23:59:59.000Z
We investigate the effects of impurities and changing ring geometry on the energetics of quantum rings under different magnetic field strengths. We show that as the magnetic field and/or the electron number are/is increased, both the quasiperiodic...
CHAPTER 5. QUANTUM-EFFECT AND HOT-ELECTRON DEVICES Dept. of Electrical Engineering
Luryi, Serge
- 1 - CHAPTER 5. QUANTUM-EFFECT AND HOT-ELECTRON DEVICES S. Luryi Dept. of Electrical Engineering Devices 41 5.3.3 Real-Space Transfer Transistors (RSTT) 45 5.3.4 Resonant Hot-Electron And Bipolar Blockade 32 5.3 HOT-ELECTRON STRUCTURES 5.3.1 Hot Electrons In Semiconductors 37 5.3.2 Ballistic Injection
Quantum Field Effects in Stationary Electron Spin Resonance Spectroscopy
Dmitri Yerchuck; Vyacheslav Stelmakh; Yauhen Yerchak; Alla Dovlatova
2015-01-28T23:59:59.000Z
It is proved on the example of electron spin resonance (ESR) studies of anthracites, that by strong electron-photon and electron-phonon interactions the formation of the coherent system of the resonance phonons takes place. The acoustic quantum Rabi oscillations were observed for the first time in ESR-spectroscopy. Its Rabi frequency value on the first damping stage was found to be equal 920.6 kHz, being to be independent on the microwave power level in the range 20 - 6 dB [0 dB corresponds to 100 mW]. By the subsequent increase of the microwave power the stepwise transition to the phenomenon of nonlinear quantum Rabi oscillations, characterised by splitting of the oscillation group of lines into two subgroups with doubling of the total lines' number takes place. Linewidth of an individual oscillation line becomes approximately the twofold narrower, being to be equal the only to $0.004 \\pm 0.001$ G. Along with the absorption process of EM-field energy the emission process was observed. It was found, that the emission process is the realization of the acoustic spin resonance, the source of acoustic wave power in which is the system of resonance phonons, accumulated in the samples by the registration with AFC. It has been found, that the lifetime of coherent state of a collective subsystem of resonance phonons in anthracites is very long and even by room temperature it is evaluated by the value exceeding 4.6 minutes. The model of new kinds of instantons was proposed. They are considered to be similar in the mathematical structure to Su-Schrieffer-Heeger solitons with "propagation" direction along time $t$-axis instead of space $z$-axis. The proof, that the superconductivity state in the anthracite samples studied is produced at the room temperature in ESR conditions in the accordance with the theory of the quantised acoustic field, has experimentally been obtained.
Isotope Effect on Adsorbed Quantum Phases: Diffusion of H2 and D2 in Nanoporous Carbon
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Contescu, Cristian I.; Zhang, Hongxin; Olsen, Raina J.; Mamontov, Eugene; Morris, James R.; Gallego, Nidia C.
2013-06-01T23:59:59.000Z
Quasielastic neutron scattering of H2 and D2 in the same nanoporous carbon at 10–40 K demonstrates extreme quantum sieving, with D2 diffusing up to 76 times faster. D2 also shows liquidlike diffusion while H2 exhibits Chudley-Elliott jump diffusion, evidence of their different relationships with the local lattice of adsorption sites due to quantum effects on intermolecular interactions. The onset of diffusion occurs at 22–25 K for H2 and 10–13 K for D2. At these temperatures, H2 and D2 have identical thermal de Broglie wavelengths that correlate with the dominant pore size.
Quantum statistics effect in Schwinger pair production in short laser pulses
Florian Hebenstreit; Reinhard Alkofer; Gerald V. Dunne; Holger Gies
2009-10-23T23:59:59.000Z
We investigate non-perturbative pair production from vacuum (the Schwinger effect) in the focal region of two counter-propagating, ultra-short laser pulses with sub-cycle structure. We use the quantum kinetic formulation to calculate the momentum spectrum of created particles and show the extreme sensitivity to the laser frequency $\\omega$, the pulse length $\\tau$ and the carrier-envelope absolute phase $\\phi$. We apply this formalism to both fermions and bosons to illustrate the influence of quantum statistics in this type of electric background field.
Probing Hawking and Unruh effects and quantum field theory in curved space by geometric invariants
Antonio Capolupo; Giuseppe Vitiello
2013-11-12T23:59:59.000Z
The presence of noncyclic geometric invariant is revealed in all the phenomena where particle generation from vacuum or vacuum condensates appear. Aharonov--Anandan invariants then can help to study such systems and can represent a new tool to be used in order to provide laboratory evidence of phenomena particulary hard to be detected, such as Hawking and Unruh effects and some features of quantum field theory in curved space simulated by some graphene morphologies. It is finally suggested that a very precise quantum thermometer can be built by exploiting geometric invariants properties.
Driscoll, Kristina, E-mail: kmdsps@rit.edu; Bennett, Mitchell F.; Polly, Stephen J.; Forbes, David V.; Hubbard, Seth M., E-mail: smhsps@rit.edu [NanoPower Research Laboratories, Rochester Institute of Technology, Rochester, New York (United States)
2014-01-13T23:59:59.000Z
The effect of the position of InAs quantum dots (QD) within the intrinsic region of pin-GaAs solar cells is reported. Simulations suggest placing the QDs in regions of reduced recombination enables a recovery of open-circuit voltage (V{sub OC}). Devices with the QDs placed in the center and near the doped regions of a pin-GaAs solar cell were experimentally investigated. While the V{sub OC} of the emitter-shifted device was degraded, the center and base-shifted devices exhibited V{sub OC} comparable to the baseline structure. This asymmetry is attributed to background doping which modifies the recombination profile and must be considered when optimizing QD placement.
Unknown
2005-06-30T23:59:59.000Z
to consider non-isochoric effects, by which the error introduced into energy and entropy calculations and the validity of the design were evaluated. The simulations were done for methane over a range of densities from 500 to 25,000 mol m[] (0.05 < p[] < 2...
Compact modeling of quantum effects in double gate MOSFETs
Wang, Wei
2007-01-01T23:59:59.000Z
However, ultrathin gate oxide will lead to high gate leakagethe high enough oxide barrier confinement leads to zero waveoxide becomes significant. The random dopant fluctuation effects increase with shrinking device size and leads
Wu, Zhigang
Quantum Monte Carlo calculations of the energy-level alignment at hybrid interfaces: Role of many; published 29 May 2009 An approach is presented for obtaining a highly accurate description of the energy-level alignment at hybrid interfaces, using quantum Monte Carlo calculations to include many-body effects
Building Green in Greensburg: City Hall Building
Office of Energy Efficiency and Renewable Energy (EERE)
This poster highlights energy efficiency, renewable energy, and sustainable features of the high-performing City Hall building in Greensburg, Kansas.
Hall Magnetohydrodynamics of weakly-ionized plasma
B. P. Pandey; Mark Wardle
2006-08-02T23:59:59.000Z
We show that the Hall scale in a weakly ionized plasma depends on the fractional ionization of the medium and, Hall MHD description becomes important whenever the ion-neutral collision frequency is comparable to the ion-gyration frequency, or, the ion-neutral collisional mean free path is smaller than the ion gyro-radius. Wave properties of a weakly-ionized plasma also depends on the fractional ionization and plasma Hall parameters, and whistler mode is the most dominant mode in such a medium. Thus Hall MHD description will be important in astrophysical disks, dark molecular clouds, neutron star crusts, and, solar and planetary atmosphere.
Henderson Hall's Education and Career Fair
Broader source: Energy.gov [DOE]
Location: Smith Gym, Henderson Hall, Arlington, VAPOC: Donna FriendWebsite: http://www.mccshh.com/EducationCareerFairFall2014.html
Hall viscosity from gauge/gravity duality
Omid Saremi; Dam Thanh Son
2011-03-24T23:59:59.000Z
In (2+1)-dimensional systems with broken parity, there exists yet another transport coefficient, appearing at the same order as the shear viscosity in the hydrodynamic derivative expansion. In condensed matter physics, it is referred to as "Hall viscosity". We consider a simple holographic realization of a (2+1)-dimensional isotropic fluid with broken spatial parity. Using techniques of fluid/gravity correspondence, we uncover that the holographic fluid possesses a nonzero Hall viscosity, whose value only depends on the near-horizon region of the background. We also write down a Kubo's formula for the Hall viscosity. We confirm our results by directly computing the Hall viscosity using the formula.
Effective Lagrangians for quantum many-body systems
Jens O. Andersen; Tomas Brauner; Christoph P. Hofmann; Aleksi Vuorinen
2014-06-13T23:59:59.000Z
The low-energy and low-momentum dynamics of systems with a spontaneously broken continuous symmetry is dominated by the ensuing Nambu-Goldstone bosons. It can be conveniently encoded in a model-independent effective field theory whose structure is fixed by symmetry up to a set of effective coupling constants. We construct the most general effective Lagrangian for the Nambu-Goldstone bosons of spontaneously broken global internal symmetry up to the fourth order in derivatives. Rotational invariance and spatial dimensionality of one, two or three are assumed in order to obtain compact explicit expressions, but our method is completely general and can be applied without modifications to condensed matter systems with a discrete space group as well as to higher-dimensional theories. The general low-energy effective Lagrangian for relativistic systems follows as a special case. We also discuss the effects of explicit symmetry breaking and classify the corresponding terms in the Lagrangian. Diverse examples are worked out in order to make the results accessible to a wide theoretical physics community.
Vladimir A. Miransky; Igor A. Shovkovy
2015-03-02T23:59:59.000Z
A range of quantum field theoretical phenomena driven by external magnetic fields and their applications in relativistic systems and quasirelativistic condensed matter ones, such as graphene and Dirac/Weyl semimetals, are reviewed. We start by introducing the underlying physics of the magnetic catalysis. The dimensional reduction of the low-energy dynamics of relativistic fermions in an external magnetic field is explained and its role in catalyzing spontaneous symmetry breaking is emphasized. The general theoretical consideration is supplemented by the analysis of the magnetic catalysis in quantum electrodynamics, chromodynamics and quasirelativistic models relevant for condensed matter physics. By generalizing the ideas of the magnetic catalysis to the case of nonzero density and temperature, we argue that other interesting phenomena take place. The chiral magnetic and chiral separation effects are perhaps the most interesting among them. In addition to the general discussion of the physics underlying chiral magnetic and separation effects, we also review their possible phenomenological implications in heavy-ion collisions and compact stars. We also discuss the application of the magnetic catalysis ideas for the description of the quantum Hall effect in monolayer and bilayer graphene, and conclude that the generalized magnetic catalysis, including both the magnetic catalysis condensates and the quantum Hall ferromagnetic ones, lies at the basis of this phenomenon. We also consider how an external magnetic field affects the underlying physics in a class of three-dimensional quasirelativistic condensed matter systems, Dirac semimetals. While at sufficiently low temperatures and zero density of charge carriers, such semimetals are expected to reveal the regime of the magnetic catalysis, the regime of Weyl semimetals with chiral asymmetry is realized at nonzero density...
Vladimir A. Miransky; Igor A. Shovkovy
2015-04-10T23:59:59.000Z
A range of quantum field theoretical phenomena driven by external magnetic fields and their applications in relativistic systems and quasirelativistic condensed matter ones, such as graphene and Dirac/Weyl semimetals, are reviewed. We start by introducing the underlying physics of the magnetic catalysis. The dimensional reduction of the low-energy dynamics of relativistic fermions in an external magnetic field is explained and its role in catalyzing spontaneous symmetry breaking is emphasized. The general theoretical consideration is supplemented by the analysis of the magnetic catalysis in quantum electrodynamics, chromodynamics and quasirelativistic models relevant for condensed matter physics. By generalizing the ideas of the magnetic catalysis to the case of nonzero density and temperature, we argue that other interesting phenomena take place. The chiral magnetic and chiral separation effects are perhaps the most interesting among them. In addition to the general discussion of the physics underlying chiral magnetic and separation effects, we also review their possible phenomenological implications in heavy-ion collisions and compact stars. We also discuss the application of the magnetic catalysis ideas for the description of the quantum Hall effect in monolayer and bilayer graphene, and conclude that the generalized magnetic catalysis, including both the magnetic catalysis condensates and the quantum Hall ferromagnetic ones, lies at the basis of this phenomenon. We also consider how an external magnetic field affects the underlying physics in a class of three-dimensional quasirelativistic condensed matter systems, Dirac semimetals. While at sufficiently low temperatures and zero density of charge carriers, such semimetals are expected to reveal the regime of the magnetic catalysis, the regime of Weyl semimetals with chiral asymmetry is realized at nonzero density...
Effects of time ordering in quantum nonlinear optics
Nicolás Quesada; J. E. Sipe
2014-07-25T23:59:59.000Z
We study time ordering corrections to the description of spontaneous parametric down-conversion (SPDC), four wave mixing (SFWM) and frequency conversion (FC) using the Magnus expansion. Analytic approximations to the evolution operator that are unitary are obtained. They are Gaussian preserving, and allow us to understand order-by-order the effects of time ordering. We show that the corrections due to time ordering vanish exactly if the phase matching function is sufficiently broad. The calculation of the effects of time ordering on the joint spectral amplitude of the photons generated in spontaneous SPDC and SFWM are reduced to quadrature.
Henry P. Stapp
2008-03-11T23:59:59.000Z
A simple exactly solvable model is given of the dynamical coupling between a person's classically described perceptions and that person's quantum mechanically described brain. The model is based jointly upon von Neumann's theory of measurement and the empirical findings of close connections between conscious intentions and synchronous oscillations in well separated parts of the brain. A quantum-Zeno-effect-based mechanism is described that allows conscious intentions to influence brain activity in a functionally appropriate way. The robustness of this mechanism in the face of environmental decoherence effects is emphasized.
The Aharonov-Bohm effect: A quantum or a relativistic phenomenon?
K. Wilhelm; B. N. Dwivedi
2014-08-23T23:59:59.000Z
The Aharonov-Bohm effect is considered by most authors as a quantum effect, but a generally accepted explanation does not seem to be available. The phenomenon is studied here under the assumption that hypothetical electric dipole distributions configured by moving charges in the solenoid act on the electrons as test particles. The relative motions of the interacting charged particles introduce relativistic time dilations. The massless dipoles are postulated as part of an impact model that has recently been proposed to account for the far-reaching electrostatic forces between charged particles described by Coulomb's law. The model provides a quantitative explanation of the Aharonov-Bohm effect.
Effect of laser phase noise on the fidelity of optomechanical quantum memory
Farnaz Farman; Alireza Bahrampour
2015-03-15T23:59:59.000Z
Optomechanical and electromechanical cavities have been widely used in quantum memories and quantum transducers. We theoretically investigate the robustness of opto(electro)-mechanical quan- tum memories against the noise of the control laser. By solving the Langevin equations and using the covariance matrix formalism in the presence of laser noise, the storing fidelity of Gaussian states is obtained. It is shown that, the destructive effect of phase noise is more significant in higher values of coupling laser amplitude and optomechanical coupling strength G. However, by further increasing coupling coefficient, the interaction time between photons and phonons decreases below the coherence time of laser frequency noise and the destructive effect of laser phase noise on the storing fidelity drops as well.
Quantum statistical correlations in thermal field theories: Boundary effective theory
Bessa, A. [Escola de Ciencias e Tecnologia, Universidade Federal do Rio Grande do Norte, Caixa Postal 1524, 59072-970, Natal, RN (Brazil); Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970, Sao Paulo, SP (Brazil); Brandt, F. T. [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970, Sao Paulo, SP (Brazil); Carvalho, C. A. A. de; Fraga, E. S. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21941-972, Rio de Janeiro, RJ (Brazil)
2010-09-15T23:59:59.000Z
We show that the one-loop effective action at finite temperature for a scalar field with quartic interaction has the same renormalized expression as at zero temperature if written in terms of a certain classical field {phi}{sub c}, and if we trade free propagators at zero temperature for their finite-temperature counterparts. The result follows if we write the partition function as an integral over field eigenstates (boundary fields) of the density matrix element in the functional Schroedinger field representation, and perform a semiclassical expansion in two steps: first, we integrate around the saddle point for fixed boundary fields, which is the classical field {phi}{sub c}, a functional of the boundary fields; then, we perform a saddle-point integration over the boundary fields, whose correlations characterize the thermal properties of the system. This procedure provides a dimensionally reduced effective theory for the thermal system. We calculate the two-point correlation as an example.
Experimental demonstration of interaction-free all-optical switching via the quantum Zeno effect
Kevin T. McCusker; Yu-Ping Huang; Abijith Kowligy; Prem Kumar
2013-01-31T23:59:59.000Z
We experimentally demonstrate all-optical interaction-free switching using the quantum Zeno effect, achieving a high contrast of 35:1. The experimental data matches a zero-parameter theoretical model for several different regimes of operation, indicating a good understanding of the switch's characteristics. We also discuss extensions of this work that will allow for significantly improved performance, and the integration of this technology onto chip-scale devices.
Moroder, Tobias; Curty, Marcos; Luetkenhaus, Norbert [Quantum Information Theory Group, Institut fuer Theoretische Physik I, and Max-Planck Research Group, Institute of Optics, Information and Photonics, Universitaet Erlangen-Nuernberg, Staudtstrasse 7/B2, 91058 Erlangen (Germany)
2006-01-15T23:59:59.000Z
We provide a simple method to obtain an upper bound on the secret key rate that is particularly suited to analyze practical realizations of quantum key distribution protocols with imperfect devices. We consider the so-called trusted device scenario where Eve cannot modify the actual detection devices employed by Alice and Bob. The upper bound obtained is based on the available measurements results, but it includes the effect of the noise and losses present in the detectors of the legitimate users.
Building America Top Innovations Hall of Fame Profile - Building...
Top Innovations Hall of Fame Profile - Building America's Top Innovations Propel the Home Building Industry toward Higher Performance Building America Top Innovations Hall of Fame...
Building America Top Innovations Hall of Fame Profile - Building...
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Building America Top Innovations Hall of Fame Profile - Building Energy Optimization Analysis Method (BEopt) Building America Top Innovations Hall of Fame Profile - Building Energy...
May 20, 2014 Klarman Hall Construction Project Update
Davis, H. Floyd
May 20, 2014 Klarman Hall Construction Project Update The Klarman Hall will sound. At this signal, construction personnel will clear pedestrians from
Reid, Scott A.
-Function Analyses of photocatalytic hybrid materials for solar energy conversion James Kincaid Effect in Ozone Formation · Mixed Quantum/Classical Theory for Collisional Energy Transfer: The Intriguing Story of the Iso-Halons Mark Steinmetz (mark
Quantum Gravitational Effects on Massive Fermions during Inflation I
S. P. Miao
2012-12-03T23:59:59.000Z
We compute the one loop graviton contribution to the self-energy of a very light fermion on a locally de Sitter background. This result can be used to study the effect that a small mass has on the propagation of fermions through the sea of infrared gravitons generated by inflation. We employ dimensional regularization and obtain a fully renormalized result by absorbing all divergences with BPHZ counterterms. An interesting technical aspect of this computation is the need for two noninvariant counterterms owing to the breaking of de Sitter invariance by our gauge condition.
Town Hall with Secretary Moniz
Energy Secretary Ernest Moniz; Deputy Secretary of Energy Daniel Poneman
2013-07-18T23:59:59.000Z
In a town hall meeting with Department staff, Energy Secretary Ernest Moniz spoke about his plans for a reorganization of the Energy Department’s management structure. The plans will help better achieve the Department’s key priorities and those of the President, including implementing the President’s Climate Action Plan, “all of the above” energy strategy and nuclear security agenda. After his remarks, Moniz, joined by Deputy Secretary Dan Poneman, took questions from the audience in the Forrestal Auditorium as well as email questions from other Department locations.
Portland State University Shattuck Hall
High Performance Buildings Database
Portland, OR Portland State's Shattuck hall was originally constructed as an elementary school in 1915. In 2007 the university undertook extensive renovations of the building to bring it up to current seismic requirements. In addition to structural improvements, the design team was able to upgraded the building's aging mechanical and electrical systems, upgrade plumbing, and restore the large light wells that bring daylight into the U-shaped building. The resulting building houses Portland State's Architecture department, where students are able to learn from the exposed building systems.
Town Hall with Secretary Moniz
Energy Secretary Ernest Moniz; Deputy Secretary of Energy Daniel Poneman
2013-07-25T23:59:59.000Z
In a town hall meeting with Department staff, Energy Secretary Ernest Moniz spoke about his plans for a reorganization of the Energy Department?s management structure. The plans will help better achieve the Department?s key priorities and those of the President, including implementing the President?s Climate Action Plan, ?all of the above? energy strategy and nuclear security agenda. After his remarks, Moniz, joined by Deputy Secretary Dan Poneman, took questions from the audience in the Forrestal Auditorium as well as email questions from other Department locations.
Experimental Hall A | Jefferson Lab
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItem NotEnergy,ARMFormsGasReleaseSpeechesHall A This photo shows one of the two High
Experimental Hall B | Jefferson Lab
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItem NotEnergy,ARMFormsGasReleaseSpeechesHall A This photo shows one of the two
Experimental Hall C | Jefferson Lab
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItem NotEnergy,ARMFormsGasReleaseSpeechesHall A This photo shows one of the
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItem NotEnergy,ARMForms About Become agovEducationWelcome to Study Hall Outreach Home
BIOGRAPHIES Randolph Hall: Networks, Emergency Response,
Southern California, University of
BIOGRAPHIES Randolph Hall: Networks, Emergency Response, Mathematical Modeling Hall, the center: Emergency Response Larson, former co-director of the MIT Operations Research Center, was one of the youngest and more than 75 scientific articles, primarily in emergency response, queuing, logistics and workforce
Scanning Hall Probe Microscopy of Magnetic Vortices inVery Underdoped yttrium-barium-copper-oxide
Guikema, Janice Wynn; /SLAC, SSRL
2005-12-02T23:59:59.000Z
Since their discovery by Bednorz and Mueller (1986), high-temperature cuprate superconductors have been the subject of intense experimental research and theoretical work. Despite this large-scale effort, agreement on the mechanism of high-T{sub c} has not been reached. Many theories make their strongest predictions for underdoped superconductors with very low superfluid density n{sub s}/m*. For this dissertation I implemented a scanning Hall probe microscope and used it to study magnetic vortices in newly available single crystals of very underdoped YBa{sub 2}Cu{sub 3}O{sub 6+x} (Liang et al. 1998, 2002). These studies have disproved a promising theory of spin-charge separation, measured the apparent vortex size (an upper bound on the penetration depth {lambda}{sub ab}), and revealed an intriguing phenomenon of ''split'' vortices. Scanning Hall probe microscopy is a non-invasive and direct method for magnetic field imaging. It is one of the few techniques capable of submicron spatial resolution coupled with sub-{Phi}{sub 0} (flux quantum) sensitivity, and it operates over a wide temperature range. Chapter 2 introduces the variable temperature scanning microscope and discusses the scanning Hall probe set-up and scanner characterizations. Chapter 3 details my fabrication of submicron GaAs/AlGaAs Hall probes and discusses noise studies for a range of probe sizes, which suggest that sub-100 nm probes could be made without compromising flux sensitivity. The subsequent chapters detail scanning Hall probe (and SQUID) microscopy studies of very underdoped YBa{sub 2}Cu{sub 3}O{sub 6+x} crystals with T{sub c} {le} 15 K. Chapter 4 describes two experimental tests for visons, essential excitations of a spin-charge separation theory proposed by Senthil and Fisher (2000, 2001b). We searched for predicted hc/e vortices (Wynn et al. 2001) and a vortex memory effect (Bonn et al. 2001) with null results, placing upper bounds on the vison energy inconsistent with the theory. Chapter 5 discusses imaging of isolated vortices as a function of T{sub c}. Vortex images were fit with theoretical magnetic field profiles in order to extract the apparent vortex size. The data for the lowest T{sub c}'s (5 and 6.5 K) show some inhomogeneity and suggest that {lambda}{sub ab} might be larger than predicted by the T{sub c} {proportional_to} n{sub s}(0)/m* relation first suggested by results of Uemura et al. (1989) for underdoped cuprates. Finally, Chapter 6 examines observations of apparent ''partial vortices'' in the crystals. My studies of these features indicate that they are likely split pancake vortex stacks. Qualitatively, these split stacks reveal information about pinning and anisotropy in the samples. Collectively these magnetic imaging studies deepen our knowledge of cuprate superconductivity, especially in the important regime of low superfluid density.
Gusev, Guennady
. Bakarov4 , S. Wiedmann5 and J. C. Portal5,6,7 1 Departamento de F´isica, Universidade Federal do Paran-970, S~ao Paulo, SP, Brazil 4 Institute of Semiconductor Physics - Novosibirsk, 630090, Russia 5 GHMFL
Effect of feedback on the control of a two-level dissipative quantum system
L. C. Wang; X. L. Huang; X. X. Yi
2008-06-10T23:59:59.000Z
We show that it is possible to modify the stationary state by a feedback control in a two-level dissipative quantum system. Based on the geometric control theory, we also analyze the effect of the feedback on the time-optimal control in the dissipative system governed by the Lindblad master equation. These effects are reflected in the function $\\Delta_A(\\vec{x})$ and $\\Delta_B(\\vec{x})$ that characterize the optimal trajectories, as well as the switching function $\\Phi(t)$ and $\\theta(t),$ which characterize the switching point in time for the time-optimal trajectory.
Analysis of Effectiveness of Lyapunov Control for Non-generic Quantum States
Xiaoting Wang; Sonia Schirmer
2009-10-01T23:59:59.000Z
A Lyapunov-based control design for natural trajectory-tracking problems is analyzed for quantum states where the analysis in the generic case is not applicable. Using dynamical systems tools we show almost global asymptotic stability for stationary target states subject to certain conditions on the Hamiltonians, and discuss effectiveness of the design when these conditions are not satisfied. For pseudo-pure target states the effectiveness of the design is studied further for both stationary and non-stationary states using alternative tools.
Thermal vibration of a rectangular single-layered graphene sheet with quantum effects
Wang, Lifeng, E-mail: walfe@nuaa.edu.cn; Hu, Haiyan [State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, 210016 Nanjing (China)
2014-06-21T23:59:59.000Z
The thermal vibration of a rectangular single-layered graphene sheet is investigated by using a rectangular nonlocal elastic plate model with quantum effects taken into account when the law of energy equipartition is unreliable. The relation between the temperature and the Root of Mean Squared (RMS) amplitude of vibration at any point of the rectangular single-layered graphene sheet in simply supported case is derived first from the rectangular nonlocal elastic plate model with the strain gradient of the second order taken into consideration so as to characterize the effect of microstructure of the graphene sheet. Then, the RMS amplitude of thermal vibration of a rectangular single-layered graphene sheet simply supported on an elastic foundation is derived. The study shows that the RMS amplitude of the rectangular single-layered graphene sheet predicted from the quantum theory is lower than that predicted from the law of energy equipartition. The maximal relative difference of RMS amplitude of thermal vibration appears at the sheet corners. The microstructure of the graphene sheet has a little effect on the thermal vibrations of lower modes, but exhibits an obvious effect on the thermal vibrations of higher modes. The quantum effect is more important for the thermal vibration of higher modes in the case of smaller sides and lower temperature. The relative difference of maximal RMS amplitude of thermal vibration of a rectangular single-layered graphene sheet decreases monotonically with an increase of temperature. The absolute difference of maximal RMS amplitude of thermal vibration of a rectangular single-layered graphene sheet increases slowly with the rising of Winkler foundation modulus.
Nuclear quantum effects in water exchange around lithium and fluoride ions
Wilkins, David M; Dang, Liem X
2015-01-01T23:59:59.000Z
We employ classical and ring polymer molecular dynamics simulations to study the effect of nuclear quantum fluctuations on the structure and the water exchange dynamics of aqueous solutions of lithium and fluoride ions. While we obtain reasonably good agreement with experimental data for solutions of lithium by augmenting the Coulombic interactions between the ion and the water molecules with a standard Lennard-Jones ion-oxygen potential, the same is not true for solutions of fluoride, for which we find that a potential with a softer repulsive wall gives much better agreement. A small degree of destabilization of the first hydration shell is found in quantum simulations of both ions when compared with classical simulations, with the shell becoming less sharply defined and the mean residence time of the water molecules in the shell decreasing. In line with these modest differences, we find that the mechanisms of the exchange processes are unaffected by quantization, so a classical description of these reaction...
Effective Field Theory for the Quantum Electrodynamics of a Graphene Wire
P. Faccioli; E. Lipparini
2009-06-30T23:59:59.000Z
We study the low-energy quantum electrodynamics of electrons and holes, in a thin graphene wire. We develop an effective field theory (EFT) based on an expansion in p/p_T, where p_T is the typical momentum of electrons and holes in the transverse direction, while p are the momenta in the longitudinal direction. We show that, to the lowest-order in (p/p_T), our EFT theory is formally equivalent to the exactly solvable Schwinger model. By exploiting such an analogy, we find that the ground state of the quantum wire contains a condensate of electron-hole pairs. The excitation spectrum is saturated by electron-hole collective bound-states, and we calculate the dispersion law of such modes. We also compute the DC conductivity per unit length at zero chemical potential and find g_s =e^2/h, where g_s=4 is the degeneracy factor.
Ko, Suk-Min; Kwack, Ho-Sang; Park, Chunghyun; Yoo, Yang-Seok; Cho, Yong-Hoon, E-mail: yhc@kaist.ac.kr [Department of Physics and KI for the NanoCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of)] [Department of Physics and KI for the NanoCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); Kwon, Soon-Yong [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of) [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); School of Mechanical and Advanced Materials Engineering, Ulsan National Institute of Science and Technology, Ulsan 689-798 (Korea, Republic of); Jin Kim, Hee; Yoon, Euijoon, E-mail: eyoon@snu.ac.kr [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)] [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Si Dang, Le [Nanophysics and Semiconductors, CEA-CNRS-UJF Group, Institut Néel, CNRS Grenoble, 25 rue des Martyrs, 38042 Grenoble Cedex 9 (France)] [Nanophysics and Semiconductors, CEA-CNRS-UJF Group, Institut Néel, CNRS Grenoble, 25 rue des Martyrs, 38042 Grenoble Cedex 9 (France)
2013-11-25T23:59:59.000Z
Here, we report on the optical and structural characteristics of violet-light-emitting, ultra-thin, high-Indium-content (UTHI) InGaN/GaN multiple quantum wells (MQWs), and of conventional low-In-content MQWs, which both emit at similar emission energies though having different well thicknesses and In compositions. The spatial inhomogeneity of In content, and the potential fluctuation in high-efficiency UTHI MQWs were compared to those in the conventional low-In-content MQWs. We conclude that the UTHI InGaN MQWs are a promising structure for achieving better quantum efficiency in the visible and near-ultraviolet spectral range, owing to their strong carrier localization and reduced quantum-confined Stark effect.
Cavalier, J.; Lemoine, N.; Bonhomme, G. [IJL, Universite de Lorraine, CNRS (UMR 7198), BP 70239, 54506 Vandoeuvre-les-Nancy (France); Tsikata, S. [ICARE, CNRS (UPR 3021), 1C av. de la Recherche Scientifique, 45071 Orleans (France); Honore, C.; Gresillon, D. [LPP, CNRS (UMR 7648), Ecole Polytechnique, 91128 Palaiseau (France)
2012-08-15T23:59:59.000Z
The effect of the collective light scattering diagnostic transfer function is considered in the context of the dispersion relation of the unstable E Multiplication-Sign B mode previously reported. This transfer function is found to have a contribution to the measured frequencies and mode amplitudes which is more or less significant depending on the measurement wavenumbers and angles. After deconvolution, the experimental data are found to be possibly compatible with the idea that the mode frequency in the jet frame (after subtraction of the Doppler effect due to the plasma motion along the thruster axis) is independent of the orientation of the wave vector in the plane orthogonal to the local magnetic field.
Magnetic shielding of a laboratory Hall thruster. II. Experiments
Hofer, Richard R., E-mail: richard.r.hofer@jpl.nasa.gov; Goebel, Dan M.; Mikellides, Ioannis G.; Katz, Ira [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)
2014-01-28T23:59:59.000Z
The physics of magnetic shielding in Hall thrusters were validated through laboratory experiments demonstrating essentially erosionless, high-performance operation. The magnetic field near the walls of a laboratory Hall thruster was modified to effectively eliminate wall erosion while maintaining the magnetic field topology away from the walls necessary to retain efficient operation. Plasma measurements at the walls validate our understanding of magnetic shielding as derived from the theory. The plasma potential was maintained very near the anode potential, the electron temperature was reduced by a factor of two to three, and the ion current density was reduced by at least a factor of two. Measurements of the carbon backsputter rate, wall geometry, and direct measurement of plasma properties at the wall indicate that the wall erosion rate was reduced by a factor of 1000 relative to the unshielded thruster. These changes effectively eliminate wall erosion as a life limitation in Hall thrusters, enabling a new class of deep-space missions that could not previously be attempted.
Miller, David A. B.
Ge/SiGe Quantum Confined Stark Effect Modulators on Silicon James S. Harris, Yu-Hsuan Kuo bandwidth have been demonstrated [4]. 2. Quantum well design Ge is an indirect band gap material, but it has. In order to have good quantum confinement, SiGe barriers are used since Si and Ge have a very high direct
Gravitational quantum effects on power spectra and spectral indices with higher-order corrections
Tao Zhu; Anzhong Wang; Gerald Cleaver; Klaus Kirsten; Qin Sheng
2014-09-05T23:59:59.000Z
The uniform asymptotic approximation method provides a powerful, systematically-improved, and error-controlled approach to construct accurate analytical approximate solutions of mode functions of perturbations of the Friedmann-Robertson-Walker universe, designed especially for the cases where the relativistic linear dispersion relation is modified after gravitational quantum effects are taken into account. These include models from string/M-Theory, loop quantum cosmology and Ho\\v{r}ava-Lifshitz quantum gravity. In this paper, we extend our previous studies of the first-order approximations to high orders for the cases where the modified dispersion relation (linear or nonlinear) has only one-turning point (or zero). We obtain the general expressions for the power spectra and spectral indices of both scalar and tensor perturbations up to the third-order, at which the error bounds are $\\lesssim 0.15\\%$. As an application of these formulas, we calculate the power spectra and spectral indices in the slow-roll inflation with a nonlinear power-law dispersion relation. To check the consistency of our formulas, we further restrict ourselves to the relativistic case, and calculate the corresponding power spectra, spectral indices and runnings to the second-order. Then, we compare our results with the ones obtained by the Green function method, and show explicitly that the results obtained by these two different methods are consistent within the allowed errors.
Mode transition of a Hall thruster discharge plasma
Hara, Kentaro, E-mail: kenhara@umich.edu; Sekerak, Michael J., E-mail: msekerak@umich.edu; Boyd, Iain D.; Gallimore, Alec D. [University of Michigan, Ann Arbor, Michigan 48109 (United States)
2014-05-28T23:59:59.000Z
A Hall thruster is a cross-field plasma device used for spacecraft propulsion. An important unresolved issue in the development of Hall thrusters concerns the effect of discharge oscillations in the range of 10–30?kHz on their performance. The use of a high speed Langmuir probe system and ultra-fast imaging of the discharge plasma of a Hall thruster suggests that the discharge oscillation mode, often called the breathing mode, is strongly correlated to an axial global ionization mode. Stabilization of the global oscillation mode is achieved as the magnetic field is increased and azimuthally rotating spokes are observed. A hybrid-direct kinetic simulation that takes into account the transport of electronically excited atoms is used to model the discharge plasma of a Hall thruster. The predicted mode transition agrees with experiments in terms of the mean discharge current, the amplitude of discharge current oscillation, and the breathing mode frequency. It is observed that the stabilization of the global oscillation mode is associated with reduced electron transport that suppresses the ionization process inside the channel. As the Joule heating balances the other loss terms including the effects of wall loss and inelastic collisions, the ionization oscillation is damped, and the discharge oscillation stabilizes. A wide range of the stable operation is supported by the formation of a space charge saturated sheath that stabilizes the electron axial drift and balances the Joule heating as the magnetic field increases. Finally, it is indicated from the numerical results that there is a strong correlation between the emitted light intensity and the discharge current.
Effect of high frequency modes of medium on an open quantum system
Nirupam Dutta; A. K. Chaudhuri; P. K. Panigrahi
2014-09-09T23:59:59.000Z
We present a method to calculate the real time effective propagator of a generic open quantum system, immersed in a medium using a wave function based framework. The medium is characterised by a set of harmonic oscillators having a continuous span of frequencies. This technique has been applied to the Caldeira-Leggett model showing that high frequency modes of the medium do not contribute towards decay of the population of states of the open system. In fact, they cause a Rabi type oscillation. Moreover, our wave function based approach provides an excellent alternative to conventional formalisms involving the density matrix.
Georgiou, C. [Research Unit for Nanostructured Materials Systems, Cyprus University of Technology, P.O. Box 50329, 3603 Limassol (Cyprus); Leontiou, T. [Research Unit for Nanostructured Materials Systems, Cyprus University of Technology, P.O. Box 50329, 3603 Limassol (Cyprus); General Department, Frederich University, 1036 Nicosia (Cyprus); Kelires, P. C., E-mail: pantelis.kelires@cut.ac.cy [Research Unit for Nanostructured Materials Systems, Cyprus University of Technology, P.O. Box 50329, 3603 Limassol (Cyprus); Department of Mechanical and Materials Science Engineering, Cyprus University of Technology, P.O. Box 50329, 3603 Limassol (Cyprus)
2014-07-15T23:59:59.000Z
Atomistic Monte Carlo simulations, coupling thermodynamic and kinetic effects, resolve a longstanding controversy regarding the origin of composition profiles in heteroepitaxial SiGe quantum dots. It is shown that profiles with cores rich in the unstrained (Si) component derive from near-equilibrium processes and intraisland diffusion. Profiles with cores rich in the strained (Ge) component are of nonequilibrium nature, i.e., they are strain driven but kinetically limited. They are shaped by the distribution of kinetic barriers of atomic diffusion in the islands. The diffusion pathways are clearly revealed for the first time. Geometrical kinetics play a minor role.
Quantum transport in crystals: effective-mass theorem and k.p Hamiltonians
Luigi Barletti; Naoufel Ben Abdallah
2014-11-14T23:59:59.000Z
In this paper the effective mass approximation and k.p multi-band models, describing quantum evolution of electrons in a crystal lattice, are discussed. Electrons are assumed to move in both a periodic potential and a macroscopic one. The typical period of the periodic potential is assumed to be very small, while the macroscopic potential acts on a much bigger length scale. Such homogenization asymptotic is investigated by using the envelope-function decomposition of the electron wave function. If the external potential is smooth enough, the k.p and effective mass models, well known in solid-state physics, are proved to be close (in strong sense) to the exact dynamics. Moreover, the position density of the electrons is proved to converge weakly to its effective mass approximation.
Steric, Quantum, and Electrostatic Effects on S{sub N}2 Reaction Barriers in Gas Phase
Liu, Shubin; Hu, Hao; Pedersen, Lee G.
2010-05-13T23:59:59.000Z
Biomolecular nucleophilic substitution reactions, S{sub N}2, are fundamental and commonplace in chemistry. It is the well-documented experimental finding in the literature that vicinal substitution with bulkier groups near the reaction center significantly slows the reaction due to steric hindrance, but theoretical understanding in the quantitative manner about factors dictating the S{sub N}2 reaction barrier height is still controversial. In this work, employing the new quantification approach that we recently proposed for the steric effect from the density functional theory framework, we investigate the relative contribution of three independent effects—steric, electrostatic, and quantum—to the S{sub N}2 barrier heights in gas phase for substituted methyl halide systems, R{sub 1}R{sub 2}R{sub 3}CX, reacting with the fluorine anion, where R{sub 1}, R{sub 2}, and R{sub 3} denote substituting groups and X = F or Cl. We found that in accordance with the experimental finding, for these systems, the steric effect dominates the transition state barrier, contributing positively to barrier heights, but this contribution is largely compensated by the negative, stabilizing contribution from the quantum effect due to the exchange-correlation interactions. Moreover, we find that it is the component from the electrostatic effect that is linearly correlated with the S{sub N}2 barrier height for the systems investigated in the present study. In addition, we compared our approach with the conventional method of energy decomposition in density functional theory as well as examined the steric effect from the wave function theory for these systems via natural bond orbital analysis.
Gluonic Excitations and Experimental Hall-D at Jefferson Lab
Stevens, Justin [MIT
2014-07-01T23:59:59.000Z
A new tagged photon beam facility is being constructed in experimental Hall-D at Jefferson Lab as a part of the 12 GeV upgrade program. The 9 GeV linearly-polarized photon beam will be produced via coherent Bremsstrahlung using the CEBAF electron beam, incident on a diamond radiator. The GlueX experiment in Hall-D will use this photon beam to search for and study the pattern of gluonic excitations in the meson spectrum produced through photoproduction reactions with a liquid hydrogen target. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons, that are formed by exciting the gluonic field that couples the quarks. A subset of these hybrid mesons are predicted to have exotic quantum numbers which cannot be formed from a simple qq^- pair, and thus provide an ideal laboratory for testing QCD in the confinement regime. In these proceedings the status of the construction and installation of the GlueX detector will be presented, in addition to simulation results for some reactions of interest in hybrid meson searches.
Gluonic Excitations and Experimental Hall-D at Jefferson Lab
Justin R. Stevens
2014-07-08T23:59:59.000Z
A new tagged photon beam facility is being constructed in experimental Hall-D at Jefferson Lab as a part of the 12 GeV upgrade program. The 9 GeV linearly-polarized photon beam will be produced via coherent Bremsstrahlung using the CEBAF electron beam, incident on a diamond radiator. The GlueX experiment in Hall-D will use this photon beam to search for and study the pattern of gluonic excitations in the meson spectrum produced through photoproduction reactions with a liquid hydrogen target. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons, that are formed by exciting the gluonic field that couples the quarks. A subset of these hybrid mesons are predicted to have exotic quantum numbers which cannot be formed from a simple $q\\bar{q}$ pair, and thus provide an ideal laboratory for testing QCD in the confinement regime. In these proceedings the status of the construction and installation of the GlueX detector will be presented, in addition to simulation results for some reactions of interest in hybrid meson searches.
Experiment Hall & Beamline | Advanced Photon Source
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1104-m-circumference optical bench. The hall floor is made of 1-ft-thick poured concrete. Usual practice in poured concrete construction is the use of evenly spaced cuts in...
The Honorable,Edward Rendell, '. City Hall
Office of Legacy Management (LM)
'. City Hall Philadelphia, Pennsylvania 19107 Dear Mayor Rendell : ', ,' . , Secretary of Energy Hazel O',teary has announced-a new approach.to.openness in the Department of Energy...
Towards a graphene-based quantum impedance standard
Kalmbach, C.-C.; Schurr, J., E-mail: juergen.schurr@ptb.de; Ahlers, F. J.; Müller, A. [Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig (Germany); Novikov, S.; Lebedeva, N. [Department of Micro- and Nanosciences, Aalto University, Micronova, Tietotie 3, 02150 Espoo (Finland); Satrapinski, A. [MIKES, Tekniikantie 1, P.O. Box, 02151 Espoo (Finland)
2014-08-18T23:59:59.000Z
Precision measurements of the quantum Hall resistance with alternating current (ac) in the kHz range were performed on epitaxial graphene in order to assess its suitability as a quantum standard of impedance. The quantum Hall plateaus measured with alternating current were found to be flat within one part in 10{sup 7}. This is much better than for plain GaAs quantum Hall devices and shows that the magnetic-flux-dependent capacitive ac losses of the graphene device are less critical. The observed frequency dependence of about ?8?×?10{sup ?8}/kHz is comparable in absolute value to the positive frequency dependence of plain GaAs devices, but the negative sign is attributed to stray capacitances which we believe can be minimized by a careful design of the graphene device. Further improvements thus may lead to a simpler and more user-friendly quantum standard for both resistance and impedance.
Electron Liquids in Semiconductor Quantum Structures
Aron Pinczuk
2009-05-25T23:59:59.000Z
The groups led by Stormer and Pinczuk have focused this project on goals that seek the elucidation of novel many-particle effects that emerge in two-dimensional electron systems (2DES) as the result from fundamental quantum interactions. This experimental research is conducted under extreme conditions of temperature and magnetic field. From the materials point of view, the ultra-high mobility systems in GaAs/AlGaAs quantum structures continue to be at the forefront of this research. The newcomer materials are based on graphene, a single atomic layer of graphite. The graphene research is attracting enormous attention from many communities involved in condensed matter research. The investigated many-particle phenomena include the integer and fractional quantum Hall effect, composite fermions, and Dirac fermions, and a diverse group of electron solid and liquid crystal phases. The Stormer group performed magneto-transport experiments and far-infrared spectroscopy, while the Pinczuk group explores manifestations of such phases in optical spectra.
Controlling atomistic processes on Pb films via quantum size effects and lattice rotation
Binz, Steven
2012-06-14T23:59:59.000Z
The two main techniques used to record the data in this dissertation were Spot Profile Analysis - Low Energy Electron Diffraction (SPA-LEED) and Scanning Tunneling Microscopy (STM). A specific data analysis technique for LEED data called G(S) curves is described in depth. G(S) curves can provide a great deal of structural information about the surface; including step heights, island size, and island separation. The effects of quantum size effects (QSE) on the diffusion and critical island sizes of Pb and In on Pb #12;films are reported. Pb depositions on the 2D In phases {radical}3 and {radical}31 to see how the phases affect the Pb growth and its strong QSE are reported.
Effects of Interface Disorder on Valley Splitting in SiGe/Si/SiGe Quantum Wells
Zhengping Jiang; Neerav Kharche; Timothy Boykin; Gerhard Klimeck
2012-03-06T23:59:59.000Z
A sharp potential barrier at the Si/SiGe interface introduces valley splitting (VS), which lifts the 2-fold valley degeneracy in strained SiGe/Si/SiGe quantum wells (QWs). This work examines in detail the effects of Si/SiGe interface disorder on the VS in an atomistic tight binding approach based on statistical sampling. VS is analyzed as a function of electric field, QW thickness, and simulation domain size. Strong electric fields push the electron wavefunctions into the SiGe buffer and introduce significant VS fluctuations from device to device. A Gedankenexperiment with ordered alloys sheds light on the importance of different bonding configurations on VS. We conclude that a single SiGe band offset and effective mass cannot comprehend the complex Si/SiGe interface interactions that dominate VS.
Effects of Interface Disorder on Valley Splitting in SiGe/Si/SiGe Quantum Wells
Jiang, Zhengping; Boykin, Timothy; Klimeck, Gerhard
2011-01-01T23:59:59.000Z
A sharp potential barrier at the Si/SiGe interface introduces valley splitting (VS), which lifts the 2-fold valley degeneracy in strained SiGe/Si/SiGe quantum wells (QWs). This work examines in detail the effects of Si/SiGe interface disorder on the VS in an atomistic tight binding approach based on statistical sampling. VS is analyzed as a function of electric field, QW thickness, and simulation domain size. Strong electric fields push the electron wavefunctions into the SiGe buffer and introduce significant VS fluctuations from device to device. A Gedankenexperiment with ordered alloys sheds light on the importance of different bonding configurations on VS. We conclude that a single SiGe band offset and effective mass cannot comprehend the complex Si/SiGe interface interactions that dominate VS.
Baishali Chakraborty; Kumar S. Gupta; Siddhartha Sen
2012-08-03T23:59:59.000Z
We study the combined effect of a conical topological defect and a Coulomb charge impurity on the dynamics of Dirac fermions in gapped graphene. Beyond a certain strength of the Coulomb charge, quantum instability sets in, which demarcates the boundary between sub and supercritical values of the charge. In the subcritical regime, for certain values of the system parameters, the allowed boundary conditions in gapped graphene cone can be classified in terms of a single real parameter. We show that the observables such as local density of states, scattering phase shifts and the bound state spectra are sensitive to the value of this real parameter, which is interesting from an empirical point of view. For a supercritical Coulomb charge, we analyze the system with a regularized potential as well as with a zigzag boundary condition and find the effect of the sample topology on the observable features of the system.
Hall MHD reconnection in cometary magnetotail
Jovanovic, Dusan [Institute of Physics, P. O. Box 57, 11001 Belgrade (Serbia and Montenegro); Shukla, Padma Kant [Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-UniverAIP confrence style sitaet Bochum, D-44780 Bochum (Germany); Morfill, Gregor [Max-Planck-Institut fuer Extraterrestrische Physik, D-85740 Garching (Germany)
2005-10-31T23:59:59.000Z
The fine structure of cometary tails (swirls, loops and blobs) is studied in the framework of resistive magnetic reconnection without a guide field in a dusty plasma. For a high-beta plasma ({beta} {approx} 1) consisting of electrons, ions, and immobile dust grains, a two-fluid description is used to study electromagnetic perturbations with the frequency below {omega}i, propagating at an arbitrary angle, and including the effects of Hall current. A zero-order current associated with the anti-parallel magnetic configuration may exist even in the limit of zero plasma temperature in a dusty plasma due to a symmetry breaking between electrons and ions by dust grains that yields an E-vector x B-vector current. In the perturbed state, a new linear electromagnetic mode is found in dusty plasma which is evanescent below the Rao cut-off frequency and has the characteristic wavelength comparable to the ion skin depth, which enables the reconnection at short spatial scales. The role of the dust is found to be twofold, yielding a new mode outside of the current sheet and altering the continuity conditions at its edge by an inhomogeneous Doppler shift associated with the E-vector x B-vector current.
Spin hall effect in paramagnetic thin films
Xu, Huachun
2009-05-15T23:59:59.000Z
the principle of Light Emitting Diode, but changed the design to a coplanar structure with two p-n junctions. A Light-Emitting Diode [27] consists of a chip of semiconductor materials doped with impurities to create a p-n junction. When the LED is forward...
Spin hall effect in paramagnetic thin films
Xu, Huachun
2009-05-15T23:59:59.000Z
the principle of Light Emitting Diode, but changed the design to a coplanar structure with two p-n junctions. A Light-Emitting Diode [27] consists of a chip of semiconductor materials doped with impurities to create a p-n junction. When the LED is forward...
Blinking effect and the use of quantum dots in single molecule spectroscopy
Rombach-Riegraf, Verena; Oswald, Peter; Bienert, Roland; Petersen, Jan [Albert-Ludwigs-Universitaet Freiburg, Institut fuer Physikalische Chemie, Albertstrasse 23a, 79104 Freiburg (Germany)] [Albert-Ludwigs-Universitaet Freiburg, Institut fuer Physikalische Chemie, Albertstrasse 23a, 79104 Freiburg (Germany); Domingo, M.P. [Instituto de Carboquimica (CSIC), Miguel Luesma 4, 50018 Zaragoza (Spain)] [Instituto de Carboquimica (CSIC), Miguel Luesma 4, 50018 Zaragoza (Spain); Pardo, Julian [Grupo Apoptosis, Inmunidad y Cancer, Departamento Bioquimica y Biologia Molecular y Celular, Fac. Ciencias, Universidad de Zaragoza, Zaragoza (Spain) [Grupo Apoptosis, Inmunidad y Cancer, Departamento Bioquimica y Biologia Molecular y Celular, Fac. Ciencias, Universidad de Zaragoza, Zaragoza (Spain); Fundacion Aragon I-D (ARAID), Gobierno de Aragon, Zaragoza (Spain); Immune Effector Cells Group, Aragon Health Research Institute (IIS Aragon), Biomedical Research Centre of Aragon (CIBA) Fundacion Aragon I-D - ARAID, Gobierno de Aragon, Zaragoza (Spain); Graeber, P. [Albert-Ludwigs-Universitaet Freiburg, Institut fuer Physikalische Chemie, Albertstrasse 23a, 79104 Freiburg (Germany)] [Albert-Ludwigs-Universitaet Freiburg, Institut fuer Physikalische Chemie, Albertstrasse 23a, 79104 Freiburg (Germany); Galvez, E.M., E-mail: eva@icb.csic.es [Instituto de Carboquimica (CSIC), Miguel Luesma 4, 50018 Zaragoza (Spain); Immune Effector Cells Group, Aragon Health Research Institute (IIS Aragon), Biomedical Research Centre of Aragon (CIBA) Fundacion Aragon I-D - ARAID, Gobierno de Aragon, Zaragoza (Spain)
2013-01-04T23:59:59.000Z
Highlights: Black-Right-Pointing-Pointer It is possible to eliminate the blinking effect of a water-soluble QD. Black-Right-Pointing-Pointer We provide a direct method to study protein function and dynamics at the single level. Black-Right-Pointing-Pointer QD, potent tool for single molecule studies of biochemical and biological processes. -- Abstract: Luminescent semiconductor nanocrystals (quantum dots, QD) have unique photo-physical properties: high photostability, brightness and narrow size-tunable fluorescence spectra. Due to their unique properties, QD-based single molecule studies have become increasingly more popular during the last years. However QDs show a strong blinking effect (random and intermittent light emission), which may limit their use in single molecule fluorescence studies. QD blinking has been widely studied and some hypotheses have been done to explain this effect. Here we summarise what is known about the blinking effect in QDs, how this phenomenon may affect single molecule studies and, on the other hand, how the 'on'/'off' states can be exploited in diverse experimental settings. In addition, we present results showing that site-directed binding of QD to cysteine residues of proteins reduces the blinking effect. This option opens a new possibility of using QDs to study protein-protein interactions and dynamics by single molecule fluorescence without modifying the chemical composition of the solution or the QD surface.
Khan, Shabbir A
2013-01-01T23:59:59.000Z
Quantum plasma physics is a rapidly evolving research field with a very inter-disciplinary scope of potential applications, ranging from nano-scale science in condensed matter to the vast scales of astrophysical objects. The theoretical description of quantum plasmas relies on various approaches, microscopic or macroscopic, some of which have obvious relation to classical plasma models. The appropriate model should, in principle, incorporate the quantum mechanical effects such as diffraction, spin statistics and correlations, operative on the relevant scales. However, first-principle approaches such as quantum Monte Carlo and density functional theory or quantum-statistical methods such as quantum kinetic theory or non-equilibrium Green's functions require substantial theoretical and computational efforts. Therefore, for selected problems, alternative simpler methods have been put forward. In particular, the collective behavior of many-body systems is usually described within a self-consistent scheme of parti...
Effect of Ligands on Characteristics of (CdSe)13 Quantum Dot
Gao, Yang; Zhou, Bo; Kang, Seung-gu; Xin, Minsi; Yang, Ping; Dai, Xing; Wang, Zhigang; Zhou, Ruhong
2014-01-01T23:59:59.000Z
The widespread applications of quantum dots (QDs) have spurred an increasing interest in the study of their coating ligands, which can not only protect the electronic structures of the central QDs, but also control their permeability through biological membranes with both size and shape. In this work, we have used density functional theory (DFT) to investigate the electronic structures of (CdSe)13 passivated by OPMe2(CH2)nMe ligands with different lengths and various numbers of branches (Me=methyl group, n = 0, 1-3). Our results show that the absorption peak in the ultraviolet-visible (UV-vis) spectra displays a clear blue-shift, on the scale of ~100 nm, upon the binding of ligands. Once the total number of ligands bound with (CdSe)13 reached a saturated number (9 or 10), no more blue-shift occurred in the absorption peak in the UV-vis spectra. On the other hand, the aliphatic chain length of ligands has a negligible effect on the optical properties of the QD core. Analyses of the bonding characteristics confirm that optical transitions are dominantly governed by the central QD core rather than the organic passivation. Interestingly, the density of states (DOS) share similar characteristics as vibrational spectra, even though there is no coordination vibration mode between the ligands and the central QD. These findings might provide insights on the material design for the passivation of quantum dots for biomedical applications.
Exponential Decay and Fermi's Golden Rule from an Uncontrolled Quantum Zeno Effect
P. W. Bryant
2014-10-14T23:59:59.000Z
We modify the theory of the Quantum Zeno Effect to make it consistent with the postulates of quantum mechanics. This modification allows one, throughout a sequence of observations of an excited system, to address the nature of the observable and thereby to distinguish survival from non-decay, which is necessary whenever excited states are degenerate. As a consequence, one can determine which types of measurements can possibly inhibit the exponential decay of the system. We find that continuous monitoring taken as the limit of a sequence of ideal measurements will only inhibit decay in special cases, such as in well-controlled experiments. Uncontrolled monitoring of an unstable system, however, can cause exponentially decreasing non-decay probability at all times. Furthermore, calculating the decay rate for a general sequence of observations leads to a straightforward derivation of Fermi's Golden Rule, that avoids many of the conceptual difficulties normally encountered. When multiple decay channels are available, the derivation reveals how the total decay rate naturally partitions into a sum of the decay rates for the various channels, in agreement with observations. Continuous and unavoidable monitoring of an excited system by an uncontrolled environment may therefore be a mechanism by which to explain the exponential decay law.
Local dissipation effects in two-dimensional quantum Josephson junction arrays with a magnetic field
Polak, T.P.; Kopec, T.K. [Max-Planck-Institut fuer Physik komplexer Systeme, Noethnitzer Strasse 38, 01187 Dresden (Germany); Institute for Low Temperatures and Structure Research, Polish Academy of Sciences, POB 1410, 50-950 Wroclaw 2 (Poland)
2005-07-01T23:59:59.000Z
We study the quantum phase transitions in two-dimensional arrays of Josephson-couples junctions with short range Josephson couplings (given by the Josephson energy E{sub J}) and the charging energy E{sub C}. We map the problem onto the solvable quantum generalization of the spherical model that improves over the mean-field theory method. The arrays are placed on the top of a two-dimensional electron gas separated by an insulator. We include effects of the local dissipation in the presence of an external magnetic flux f={phi}/{phi}{sub 0} in square lattice for several rational fluxes f=0,(1/2),(1/3),(1/4), and (1/6). We also have examined the T=0 superconducting-insulator phase boundary as a function of a dissipation {alpha}{sub 0} for two different geometry of the lattice: square and triangular. We have found a critical value of the dissipation parameter independent on geometry of the lattice and presence magnetic field.
Near-infrared induced optical quenching effects on mid-infrared quantum cascade lasers
Guo, Dingkai, E-mail: dingk1@umbc.edu; Talukder, Muhammad Anisuzzaman; Chen, Xing [Department of Computer Science and Electrical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Cai, Hong [Center of Advanced Studies in Photonics Research (CASPR), University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Johnson, Anthony M.; Choa, Fow-Sen [Department of Computer Science and Electrical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Center of Advanced Studies in Photonics Research (CASPR), University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Khurgin, Jacob B. [Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States)
2014-06-23T23:59:59.000Z
In space communications, atmospheric absorption and Rayleigh scattering are the dominant channel impairments. Transmission using mid-infrared (MIR) wavelengths offers the benefits of lower loss and less scintillation effects. In this work, we report the telecom wavelengths (1.55??m and 1.3??m) induced optical quenching effects on MIR quantum cascade lasers (QCLs), when QCLs are operated well above their thresholds. The QCL output power can be near 100% quenched using 20?mW of near-infrared (NIR) power, and the quenching effect depends on the input NIR intensity as well as wavelength. Time resolved measurement was conducted to explore the quenching mechanism. The measured recovery time is around 14?ns, which indicates that NIR generated electron-hole pairs may play a key role in the quenching process. The photocarrier created local field and band bending can effectively deteriorate the dipole transition matrix element and quench the QCL. As a result, MIR QCLs can be used as an optical modulator and switch controlled by NIR lasers. They can also be used as “converters” to convert telecom optical signals into MIR optical signals.
Tahir, M. [PSE Division, KAUST, Thuwal 23955-6900 (Saudi Arabia); Department of Physics, University of Sargodha, Sargodha 40100 (Pakistan); Sabeeh, K. [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Shaukat, A. [Department of Physics, University of Sargodha, Sargodha 40100 (Pakistan); Schwingenschlögl, U., E-mail: Udo.Schwingenschlogl@kaust.edu.sa [PSE Division, KAUST, Thuwal 23955-6900 (Saudi Arabia)
2013-12-14T23:59:59.000Z
Since the discovery of graphene, a lot of interest has been attracted by the zeroth Landau level, which has no analog in the conventional two dimensional electron gas. Recently, lifting of the spin and valley degeneracies has been confirmed experimentally by capacitance measurements, while in transport experiments, this is difficult due to the scattering in the device. In this context, we model interaction effects on the quantum capacitance of graphene in the presence of a perpendicular magnetic field, finding good agreement with experiments. We demonstrate that the valley degeneracy is lifted by the substrate and by Kekule distortion, whereas the spin degeneracy is lifted by Zeeman interaction. The two cases can be distinguished by capacitance measurements.
Towards a Robust, Efficient Dispenser Photocathode: the Effect of Recesiation on Quantum Efficiency
Montgomery, Eric J.; Pan Zhigang; Leung, Jessica; Feldman, Donald W.; O'Shea, Patrick G. [Institute for Research in Electronics and Applied Physics, University of MD, College Park, MD 20742 (United States); Jensen, Kevin L. [Code 6843, ESTD, Naval Research Laboratory, Washington D.C. 20375-5347 (United States)
2009-01-22T23:59:59.000Z
Future electron accelerators and Free Electron Lasers (FELs) require high brightness electron sources; photocathodes for such devices are challenged to maintain long life and high electron emission efficiency (high quantum efficiency, or QE). The UMD dispenser photocathode design addresses this tradeoff of robustness and QE. In such a dispenser, a cesium-based surface layer is deposited on a porous substrate. The surface layer can be replenished from a subsurface cesium reservoir under gentle heating, allowing cesium to diffuse controllably to the surface and providing demonstrably more robust photocathodes. In support of the premise that recesiation is able to restore contaminated photocathodes, we here report controlled contamination of cesium-based surface layers with subsequent recesiation and the resulting effect on QE. Contaminant gases investigated include examples known from the vacuum environment of typical electron guns.
Josephson effect in CeCoIn{sub 5} microbridges as seen via quantum interferometry
Foyevtsov, Oleksandr; Porrati, Fabrizio; Huth, Michael [Physikalisches Institut, Goethe University, Frankfurt am Main, 60438 (Germany)
2011-07-15T23:59:59.000Z
A superconducting quantum interference device (SQUID) was prepared on a micron-sized single crystal using a selected growth domain of a thin film of CeCoIn{sub 5} grown by molecular beam epitaxy. SQUID voltage oscillations of good quality were obtained as well as interference effects stemming from the individual Josephson microbridges. The transport characteristics in the superconducting state exhibited several peculiarities which we ascribe to the periodic motion of vortices in the microbridges. The temperature dependence of the Josephson critical current shows good correspondence to the Ambegaokar-Baratoff relation, expected for the ideal Josephson junction. The results indicate a promising pathway to identify the type of order parameter in CeCoIn{sub 5} by means of phase-sensitive measurements on microbridges.
Suspending Effect on Low-Frequency Charge Noise in Graphene Quantum Dot
Xiang-Xiang Song; Hai-Ou Li; Jie You; Tian-Yi Han; Gang Cao; Tao Tu; Ming Xiao; Guang-Can Guo; Hong-Wen Jiang; Guo-Ping Guo
2014-06-16T23:59:59.000Z
Charge noise is critical in the performance of gate-controlled quantum dots (QDs). Here we show the 1/f noise for a microscopic graphene QD is substantially larger than that for a macroscopic graphene field-effect transistor (FET), increasing linearly with temperature. To understand its origin, we suspended the graphene QD above the substrate. In contrast to large area graphene FETs, we find that a suspended graphene QD has an almost-identical noise level as an unsuspended one. Tracking noise levels around the Coulomb blockade peak as a function of gate voltage yields potential fluctuations of order 1 "{\\mu}eV", almost one order larger than in GaAs/GaAlAs QDs. Edge states rather than substrate-induced disorders, appear to dominate the 1/f noise, thus affecting the coherency of graphene nano-devices.
Reduced quantum confinement effect and electron-hole separation in SiGe nanowires Michele Amato,1
Marini, Andrea
Reduced quantum confinement effect and electron-hole separation in SiGe nanowires Michele Amato,1 Using first-principles methods, we investigate the structural and electronic properties of SiGe26 studies have been carried out to investigate the structural and optoelectronic properties of Si, Ge
Alexander Hall (1) D4 Alumni Center (2) D2
Nelson, Tim
Cremona Classrooms (77) E3 Demaray Hall (DH) (8) B2 Eaton Hall (EH) (25) C3 Facility Operations Center Floor Peterson (20) C3 Corporate, Foundation, and Major Gifts, WAC (28) B3 Development, WAC (23) F3
ORIGINAL PAPER Eric J. Hall Basil V. Worgul Lubomir Smilenov
Brenner, David Jonathan
ORIGINAL PAPER Eric J. Hall Ã? Basil V. Worgul Ã? Lubomir Smilenov Carl D. Elliston Ã? David J his colleagues. E. J. Hall (&) Ã? L. Smilenov Ã? C. D. Elliston Ã? D. J. Brenner Center for Radiological
TRINITY HALL HAS INSTALLED CCTV ON THESE PREMISES FOR
Lasenby, Joan
TRINITY HALL HAS INSTALLED CCTV ON THESE PREMISES FOR YOUR SAFETY AND PROTECTION #12; Trinity Hall Trinity Lane Cambridge CB2 1TJ Tel: 01223 33 25 00 For all enquiries and questions
Waveguide effect of GaAsSb quantum wells in a laser structure based on GaAs
Aleshkin, V. Ya. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)] [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Afonenko, A. A. [Belarussian State University (Belarus)] [Belarussian State University (Belarus); Dikareva, N. V. [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation)] [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation); Dubinov, A. A., E-mail: sanya@ipm.sci-nnov.ru; Kudryavtsev, K. E.; Morozov, S. V. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)] [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Nekorkin, S. M. [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation)] [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation)
2013-11-15T23:59:59.000Z
The waveguide effect of GaAsSb quantum wells in a semiconductor-laser structure based on GaAs is studied theoretically and experimentally. It is shown that quantum wells themselves can be used as waveguide layers in the laser structure. As the excitation-power density attains a value of 2 kW/cm{sup 2} at liquid-nitrogen temperature, superluminescence at the wavelength corresponding to the optical transition in bulk GaAs (at 835 nm) is observed.
J. Wurm; K. Richter; I. Adagideli
2011-11-14T23:59:59.000Z
We investigate the effect of different edge types on the statistical properties of both the energy spectrum of closed graphene billiards and the conductance of open graphene cavities in the semiclassical limit. To this end, we use the semiclassical Green's function for ballistic graphene flakes that we have derived in Reference 1. First we study the spectral two point correlation function, or more precisely its Fourier transform the spectral form factor, starting from the graphene version of Gutzwiller's trace formula for the oscillating part of the density of states. We calculate the two leading order contributions to the spectral form factor, paying particular attention to the influence of the edge characteristics of the system. Then we consider transport properties of open graphene cavities. We derive generic analytical expressions for the classical conductance, the weak localization correction, the size of the universal conductance fluctuations and the shot noise power of a ballistic graphene cavity. Again we focus on the effects of the edge structure. For both, the conductance and the spectral form factor, we find that edge induced pseudospin interference affects the results significantly. In particular intervalley coupling mediated through scattering from armchair edges is the key mechanism that governs the coherent quantum interference effects in ballistic graphene cavities.
Non-linear hydrodynamics of axion dark matter: relative velocity effects and "quantum forces"
Marsh, David J E
2015-01-01T23:59:59.000Z
The non-linear hydrodynamic equations for axion/scalar field dark matter (DM) in the non-relativistic Madelung-Shcr\\"{o}dinger form are derived in a simple manner, including the effects of universal expansion and Hubble drag. The hydrodynamic equations are used to investigate the relative velocity between axion DM and baryons, and the moving-background perturbation theory (MBPT) derived. Axions massive enough to be all of the DM do not affect the coherence length of the relative velocity, but the MBPT equations are modified by the inclusion of the axion effective sound speed. These MBPT equations are necessary for accurately modelling the effects of axion DM on the formation of the first cosmic structures, and suggest that the 21cm power spectrum could improve constraints on axion mass by up to four orders of magnitude with respect to the current best constraints. A further application of these results uses the "quantum force" analogy to model scalar field gradient energy in a smoothed-particle hydrodynamics ...
Checklists for: Oklahoma 4-H Hall of Fame
Balasundaram, Balabhaskar "Baski"
Checklists for: Oklahoma 4-H Hall of Fame National 4-H Youth Congress Name County Oklahoma 4-H Hall of Fame National 4-H Youth Congress Oklahoma 4-H Hall of Fame has the following requirements: Oklahoma 4-H on the front page of the Oklahoma 4-H Report Form and on the heading for Section I Member must be 16 years
Making a gift: Trinity Hall is a registered charity
Lasenby, Joan
Making a gift: Trinity Hall is a registered charity and gifts to the College can be made tax. For more information please see: www.trinhall.cam.ac.uk/giving2012 Development Office, Trinity Hall)1223 765157 Trinity Hall Cambridge registered charity number 1137458 "Receiving funding has made a huge
Local Availability of mathematics and number scaling: Effects on quantum physics
Paul Benioff
2012-05-01T23:59:59.000Z
Local availability of mathematics and number scaling provide an approach to a coherent theory of physics and mathematics. Local availability of mathematics assigns separate mathematical universes, U_{x}, to each space time point, x. The mathematics available to an observer, O_{x}, at x is contained in U_{x}. Number scaling is based on extending the choice freedom of vector space bases in gauge theories to choice freedom of underlying number systems. Scaling arises in the description, in U_{x}, of mathematical systems in U_{y}. If a_{y} or \\psi_{y} is a number or a quantum state in U_{y}, then the corresponding number or state in U_{x} is r_{y,x}a_{x} or r_{y,x}\\psi_{x}. Here a_{x} and \\psi_{x} are the same number and state in U_{x} as a_{y} and \\psi_{y} are in U_{y}. If y=x+\\hat{\\mu}dx is a neighbor point of x, then the scaling factor is r_{y,x}=\\exp(\\vec{A}(x)\\cdot\\hat{\\mu}dx) where \\vec{A} is a vector field, assumed here to be the gradient of a scalar field. The effects of scaling and local availability of mathematics on quantum theory show that scaling has two components, external and internal. External scaling is shown above for a_{y} and \\psi_{y}. Internal scaling occurs in expressions with integrals or derivatives over space or space time. An example is the replacement of the position expectation value, \\int\\psi^{*}(y)y\\psi(y)dy, by \\int_{x}r_{y,x}\\psi^{*}_{x}(y_{x})y_{x}\\psi_{x}(y_{x})dy_{x}. This is an integral in U_{x}. The good agreement between quantum theory and experiment shows that scaling is negligible in a space region, L, in which experiments and calculations can be done, and results compared. L includes the solar system, but the speed of light limits the size of L to a few light years. Outside of $L$, at cosmological distances, the limits on scaling are not present.
Strain relaxation effect by nanotexturing InGaN/GaN multiple quantum well
Ramesh, V.; Kikuchi, A.; Kishino, K. [Department of Electrical and Electronics Engineering, Sophia University, Tokyo 102-8554, Japan and Nano-technology Research Center, Sophia University, Tokyo 102-8554 (Japan); CREST, JST, Saitama 332-0012 (Japan); Funato, M.; Kawakami, Y. [CREST, JST, Saitama 332-0012 (Japan); Department of Electronics Science and Engineering, Kyoto University, Kyoto 615-8510 (Japan)
2010-06-15T23:59:59.000Z
The relaxation of lattice-mismatched strain by deep postetching was systematically investigated for InGaN/GaN multiple quantum wells (MQWs). A planar heterojunction wafer, which included an In{sub 0.21}Ga{sub 0.79}N (3.2 nm)/GaN (14.8 nm) MQW, was etched by inductively coupled plasma dry etching, to fabricate high-density nanopillar, nanostripe, and nanohole arrays. The etching depth was 570 nm for all nanostructures. The diameter of the nanopillars was varied from 50 to 300 nm, then the mesa stripe width of the nanostripes and the diameter of the nanoholes were varied from 100 nm to 440 nm and 50 nm to 310 nm, respectively. The effect of strain relaxation on various optical properties was investigated. For example, in an array of nanopillars with diameter 130 nm and interval 250 nm, a large blueshift in the photoluminescence (PL) emission peak from 510 nm (as-grown) to 459 nm occurred at room temperature (RT). PL internal quantum efficiency (defined by the ratio of PL integral intensity at 300 K to that at 4.2 K) was enhanced from 34% (as-grown) to 60%, and the PL decay time at 4.2 K was reduced from 22 ns (as-grown) to 4.2 ns. These results clearly indicate the reduction of lattice-mismatched strain by postetching, which enhanced strain reduction with decreasing nanopillar diameter down to a diameter of 130 nm, where the strain reduction became saturated. The dependence of RT-PL decay time on nanopillar diameter was measured, and the surface nonradiative recombination velocity was estimated to be 5.8x10{sup 2} cm/s. This relatively slow rate indicates a little etching damage.
Plasma relaxation and topological aspects in Hall magnetohydrodynamics
Shivamoggi, B. K. [University of Central Florida, Orlando, Florida 32816-1364 (United States)
2012-07-15T23:59:59.000Z
Parker's formulation of isotopological plasma relaxation process in magnetohydrodynamics (MHD) is extended to Hall MHD. The torsion coefficient {alpha} in the Hall MHD Beltrami condition turns out now to be proportional to the potential vorticity. The Hall MHD Beltrami condition becomes equivalent to the potential vorticity conservation equation in two-dimensional (2D) hydrodynamics if the Hall MHD Lagrange multiplier {beta} is taken to be proportional to the potential vorticity as well. The winding pattern of the magnetic field lines in Hall MHD then appears to evolve in the same way as potential vorticity lines in 2D hydrodynamics.
Alan Turing, Marshall Hall, and the Alignment
Wright, Francis
Alan Turing, Marshall Hall, and the Alignment of WW2 Japanese Naval Intercepts Peter W. Donovan M work in all areas, from the Japanese codes to the German Enigma machine which Alan Turing had begun of communications intelligence to the WW2 Allies in the Pacific. Alan Turing's Work on Applied Probability
The practical revised simplex method Julian Hall
Hall, Julian
The practical revised simplex method Julian Hall School of Mathematics University of Edinburgh January 25th 2007 The practical revised simplex method #12;Overview #12;Overview Part 1: · The mathematics of linear programming #12;Overview Part 1: · The mathematics of linear programming · The simplex method
Air Temperature in the Undulator Hall
Not Available
2010-12-07T23:59:59.000Z
Various analyses have been performed recently to estimate the performance of the air conditioning (HVAC) system planned for the Undulator Hall. This reports summarizes the results and provides an upgrade plan to be used if new requirements are needed in the future. The estimates predict that with the planned loads the tunnel air temperature will be well within the allowed tolerance during normal operation.
235 Clements Hall Math Department, SMU
Xu, Sheng
Sheng Xu 235 Clements Hall Math Department, SMU Dallas, TX 75275-0156 (214) 768-2985(O), (214)768-2355(F) sxu@smu.edu http://faculty.smu.edu/sxu computational fluid dynamics and scientific computing (SMU) Engineer, April 2006 - July 2006 Steam Turbine Aerodynamics Group, GE Energy Post
Start: Statler Hotel (star) Finish: Upson Hall
Keinan, Alon
route: Green dashed line that starts from Statler Hotel and meets read line (backwards) at Bailey Hall been accomplished by a pair of local rock climbers. Uris Library (around towards the Slope) o Show west campus, downtown, Cayuga lake Uris Library (inside) o Cornell has 19 libraries which hold more
Interface effect of InSb quantum dots embedded in SiO{sub 2} matrix
Chen Dongliang; Fan Jiangwei; Wei Shiqiang [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029 (China); Li Chaosheng; Zhu Zhengang [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, PO Box 1129, Hefei 230031 (China)
2005-08-15T23:59:59.000Z
The interface effect of InSb quantum dots (QDs) embedded in SiO{sub 2} matrix has been investigated by Raman scattering spectroscopy, x-ray diffraction (XRD), and x-ray absorption fine structure (both of EXAFS and XANES). The EXAFS and XRD results show clearly that the bond length of the Sb-In first shell of the InSb QDs contracts slightly about 0.02 A compared with that of the bulk InSb. The Raman scattering spectrum of the InSb QDs reveals that the lattice contraction partly weakens the phonon confinement effect. The coordination geometry at the interface of the InSb QDs is mainly Sb (In)-O covalent bridge bonds. The Sb K-XANES calculations of InSb QDs embedded in SiO{sub 2} matrix based on FEFF8 indicate that the intensity increase and the broadening of the white line peak of Sb atoms are essentially attributed to both the increase of Sb p-hole population and the change of Sb intra-atomic potential {mu}{sub 0}(E) affected by the SiO{sub 2} matrix. Our results show that the interface effect between the InSb QDs and the SiO{sub 2} matrix leads not only to the slight lattice contraction of InSb QDs and the large structural distortion in the interface area of InSb QDs, but also to the significant change of the Sb intra-atomic potential and the obvious charge redistribution around Sb atoms.
Minnesota, University of
Systematic Approach for Computing Zero-Point Energy, Quantum Partition Function, and Tunneling, and a proton-transfer barrier modeled by the Eckart potential. The zero-point energy, quantum partition agreement with the ground-state energy (zero-point energy), and the position of the centroid potential
Takagi, Hidetsugu; Kunugita, Hideyuki; Ema, Kazuhiro [Department of Physics, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Sato, Mikio; Takeoka, Yuko [Department of Materials and Life Sciences, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan)
2013-12-04T23:59:59.000Z
We have investigated experimentally excitonic properties in organic-inorganic hybrid multi quantum well crystals, (C{sub 4}H{sub 9}NH{sub 3}){sub 2}PbBr{sub 4} and (C{sub 6}H{sub 5}?C{sub 2}H{sub 4}NH{sub 3}){sub 2}PbBr{sub 4}, by measuring photoluminescence, reflectance, photoluminescence excitation spectra. In these materials, the excitonic binding energies are enhanced not only by quantum confinement effect (QCE) but also by image charge effect (ICE), since the dielectric constant of the barrier layers is much smaller than that of the well layers. By comparing the 1s-exciton and 2s-exciton energies, we have investigated the influence of ICE with regard to the difference of the Bohr radius.
A functional approach to quantum friction: effective action and dissipative force
M. Belén Farías; César D. Fosco; Fernando C. Lombardo; Francisco D. Mazzitelli; Adrián E. Rubio López
2014-12-31T23:59:59.000Z
We study the Casimir friction due to the relative, uniform, lateral motion of two parallel semitransparent mirrors coupled to a vacuum real scalar field, $\\phi$. We follow a functional approach, whereby nonlocal terms in the action for $\\phi$, concentrated on the mirrors' locii, appear after functional integration of the microscopic degrees of freedom. This action for $\\phi$, which incorporates the relevant properties of the mirrors, is then used as the starting point for two complementary evaluations: Firstly, we calculate the { in-out} effective action for the system, which develops an imaginary part, hence a non-vanishing probability for the decay (because of friction) of the initial vacuum state. Secondly, we evaluate another observable: the vacuum expectation value of the frictional force, using the { in-in} or Closed Time Path formalism. Explicit results are presented for zero-width mirrors and half-spaces, in a model where the microscopic degrees of freedom at the mirrors are a set of identical quantum harmonic oscillators, linearly coupled to $\\phi$
Effect of graphene on photoluminescence properties of graphene/GeSi quantum dot hybrid structures
Chen, Y. L.; Ma, Y. J.; Wang, W. Q.; Ding, K.; Wu, Q.; Fan, Y. L.; Yang, X. J.; Zhong, Z. Y.; Jiang, Z. M., E-mail: zmjiang@fudan.edu.cn [State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) and Department of Physics, Fudan University, Shanghai 200433 (China); Chen, D. D.; Xu, F. [SHU-SolarE R and D Lab, Department of Physics, College of Science, Shanghai University, Shanghai 200444 (China)
2014-07-14T23:59:59.000Z
Graphene has been discovered to have two effects on the photoluminescence (PL) properties of graphene/GeSi quantum dot (QD) hybrid structures, which were formed by covering monolayer graphene sheet on the multilayer ordered GeSi QDs sample surfaces. At the excitation of 488?nm laser line, the hybrid structure had a reduced PL intensity, while at the excitation of 325?nm, it had an enhanced PL intensity. The attenuation in PL intensity can be attributed to the transferring of electrons from the conducting band of GeSi QDs to the graphene sheet. The electron transfer mechanism was confirmed by the time resolved PL measurements. For the PL enhancement, a mechanism called surface-plasmon-polariton (SPP) enhanced absorption mechanism is proposed, in which the excitation of SPP in the graphene is suggested. Due to the resonant excitation of SPP by incident light, the absorption of incident light is much enhanced at the surface region, thus leading to more exciton generation and a PL enhancement in the region. The results may be helpful to provide us a way to improve optical properties of low dimensional surface structures.
Miura, H., E-mail: miura.hideaki@nifs.ac.jp [Department of Helical Plasma Research, National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Araki, K. [Faculty of Engineering, Okayama University of Science, 1-1 Ridai-cho, Okayama 700-0005 (Japan)
2014-07-15T23:59:59.000Z
Hall effects on local structures in homogeneous, isotropic, and incompressible magnetohydrodynamic turbulence are studied numerically. The transition of vortices from sheet-like to tubular structures induced by the Hall term is found, while the kinetic energy spectrum does not distinguish the two types of structures. It is shown by the use of the sharp low-pass filter that the transition occurs not only in the scales smaller than the ion skin depth but also in a larger scale. The transition is related with the forward energy transfer in the spectral space. Analyses by the use of the sharp low-pass filter show that the nonlinear energy transfer associated with the Hall term is dominated by the forward transfer and relatively local in the wave number space. A projection of the simulation data to a Smagorinsky-type sub-grid-scale model shows that the high wave number component of the Hall term may possibly be replaced by the model effectively.
The impact of Hall physics on magnetized high energy density plasma jets
Gourdain, P.-A.; Seyler, C. E.; Atoyan, L.; Greenly, J. B.; Hammer, D. A.; Kusse, B. R.; Pikuz, S. A.; Potter, W. M.; Schrafel, P. C.; Shelkovenko, T. A. [Cornell University, Ithaca, New York 14853 (United States)] [Cornell University, Ithaca, New York 14853 (United States)
2014-05-15T23:59:59.000Z
Hall physics is often neglected in high energy density plasma jets due to the relatively high electron density of such jets (n{sub e}???10{sup 19}?cm{sup ?3}). However, the vacuum region surrounding the jet has much lower densities and is dominated by Hall electric field. This electric field redirects plasma flows towards or away from the axis, depending on the radial current direction. A resulting change in the jet density has been observed experimentally. Furthermore, if an axial field is applied on the jet, the Hall effect is enhanced and ignoring it leads to serious discrepancies between experimental results and numerical simulations. By combining high currents (?1 MA) and magnetic field helicity (15° angle) in a pulsed power generator such as COBRA, plasma jets can be magnetized with a 10?T axial field. The resulting field enhances the impact of the Hall effect by altering the density profile of current-free plasma jets and the stability of current-carrying plasma jets (e.g., Z-pinches)
Nagashima, H., E-mail: nagashima@nanoint.ifs.tohoku.ac.jp [School of Engineering, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Tsuda, S. [Department of Mechanical Systems Engineering, Shinshu University, Nagano 380-8553 (Japan)] [Department of Mechanical Systems Engineering, Shinshu University, Nagano 380-8553 (Japan); Tsuboi, N. [Department of Mechanical and Control Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan)] [Department of Mechanical and Control Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan); Koshi, M. [Graduate School of Environment and Information Science, Yokohama National University, Yokohama 240-8501 (Japan)] [Graduate School of Environment and Information Science, Yokohama National University, Yokohama 240-8501 (Japan); Hayashi, K. A. [Department of Mechanical Engineering, Aoyama Gakuin University, Sagamihara 229-8558 (Japan)] [Department of Mechanical Engineering, Aoyama Gakuin University, Sagamihara 229-8558 (Japan); Tokumasu, T. [Institute of Fluid Science, Tohoku University, Sendai 980-8577 (Japan)] [Institute of Fluid Science, Tohoku University, Sendai 980-8577 (Japan)
2014-04-07T23:59:59.000Z
In this paper, we describe the analysis of the thermodynamic properties of cryogenic hydrogen using classical molecular dynamics (MD) and path integral MD (PIMD) method to understand the effects of the quantum nature of hydrogen molecules. We performed constant NVE MD simulations across a wide density–temperature region to establish an equation of state (EOS). Moreover, the quantum effect on the difference of molecular mechanism of pressure–volume–temperature relationship was addressed. The EOS was derived based on the classical mechanism idea only using the MD simulation results. Simulation results were compared with each MD method and experimental data. As a result, it was confirmed that although the EOS on the basis of classical MD cannot reproduce the experimental data of saturation property of hydrogen in the high-density region, the EOS on the basis of PIMD well reproduces those thermodynamic properties of hydrogen. Moreover, it was clarified that taking quantum effects into account makes the repulsion force larger and the potential well shallower. Because of this mechanism, the intermolecular interaction of hydrogen molecules diminishes and the virial pressure increases.
Dirac Quantization and Fractional Magnetoelectric Effect on Interacting Topological Insulators
K. -S. Park; H. Han
2010-10-10T23:59:59.000Z
We use Dirac quantization of flux to study fractional charges and axion angles \\theta in interacting topological insulators with gapless surface modes protected by time-reversal symmetry. In interacting topological insulators, there are two types of fractional axion angle due to conventional odd and nontrivial even flux quantization at the boundary. On even flux quantization in a gapped time reversal invariant system, we show that there is a halved quarter fractional quantum Hall effect on the surface with Hall conductance of p/4q e2/2h with p and q odd integers. The gapless surface modes can be characterized by a nontrivial Z2 anomaly emerged from the even flux quantization. It is suggested that the electron can be regarded as a bound state of fractionally charged quarks confined by a nonabelian color gauge field on the Dirac quantization of complex spinor fields.
AlGaN/GaN/AlN quantum-well field-effect transistors with highly resistive AlN epilayers
Jiang, Hongxing
AlGaN/GaN/AlN quantum-well field-effect transistors with highly resistive AlN epilayers Z. Y. Fana 66506-2601 Received 23 November 2005; accepted 5 January 2006; published online 16 February 2006 AlGaN/GaN/AlN quantum-well field-effect transistors have been demonstrated. By replacing a semi-insulating GaN epilayer
Welcome to the Faculty of Engineering and Applied Science Beamish Munro Hall
Ellis, Randy
Hall Tour #3 1:30 pm 2:05 pm 2:10 pm 2:40 pm 2:45 pm 3:30 pm · Engineering Physics, Stirling Hall Tour #1 · Engineering Physics, Stirling Hall Tour #2 · Engineering Physics, Stirling Hall Tour #3 1Welcome to the Faculty of Engineering and Applied Science Beamish Munro Hall 45 Union Street
Fast Camera Imaging of Hall Thruster Ignition
C.L. Ellison, Y. Raitses and N.J. Fisch
2011-02-24T23:59:59.000Z
Hall thrusters provide efficient space propulsion by electrostatic acceleration of ions. Rotating electron clouds in the thruster overcome the space charge limitations of other methods. Images of the thruster startup, taken with a fast camera, reveal a bright ionization period which settles into steady state operation over 50 ?s. The cathode introduces azimuthal asymmetry, which persists for about 30 ?s into the ignition. Plasma thrusters are used on satellites for repositioning, orbit correction and drag compensation. The advantage of plasma thrusters over conventional chemical thrusters is that the exhaust energies are not limited by chemical energy to about an electron volt. For xenon Hall thrusters, the ion exhaust velocity can be 15-20 km/s, compared to 5 km/s for a typical chemical thruster
U.S. WRESTLING FEDERATION HALL
Veiga, Pedro Manuel Barbosa
S-86 S-87 S-36 S-85 S-90 S-75 S-76 HOUSE #6 S-89 S-91 OFFICE CENTER AGRICULTURE U.S.D.A. S-92 S-88. SMITH HALL ALUMNI CENTER HOUSING - JPI PHASE 1 BUILDING 3 HOUSING - JPI PHASE 1 BUILDING 4 STUDENT UNION. LAUNDRY RESOURCE Y CAGE LAB. POULTRY BATTERY LAB. BROODER FIRE TECH. OUTDOOR LAB. MO. LAB. GY CONS. CHAPEL
Mario G. Silveirinha
2014-06-09T23:59:59.000Z
Here, we develop a comprehensive quantum theory for the phenomenon of quantum friction. Based on a theory of macroscopic quantum electrodynamics for unstable systems, we calculate the quantum expectation of the friction force, and link the friction effect to the emergence of system instabilities related to the Cherenkov effect. These instabilities may occur due to the hybridization of particular guided modes supported by the individual moving bodies, and selection rules for the interacting modes are derived. It is proven that the quantum friction effect can take place even when the interacting bodies are lossless and made of nondispersive dielectrics.
The effect of surface conductance on lateral gated quantum devices in Si/SiGe heterostructures
Lin, Xi
Quantum dots in Si/SiGe heterostructures are expected to have relatively long electron spin decoherence times, because of the low density of nuclear spins and the weak coupling between nuclear and electron spins. We provide ...
Sadi, Toufik; Oksanen, Jani; Tulkki, Jukka [Department of Biomedical Engineering and Computational Sciences, Aalto University, P.O. Box 12200, FI-00076 Aalto (Finland)
2013-12-14T23:59:59.000Z
Recent experimental work has shown significant luminescence enhancement from near-surface quantum-well (QW) structures using metallic grating to convert surface plasmon (SP) modes into radiative modes. This work introduces a detailed theoretical study of plasmonic losses and the role of SPs in improving light extraction from grated light-emitting QW structures, using the fluctuational electrodynamics method. The method explains experimental results demonstrating emission enhancement, light scattering, and plasmonic coupling in the structures. We study these effects in angle-resolved reflectometry and luminescence setups in InGaN QW structures with silver grating. In contrast to experiments, our model allows direct calculation of the optical losses. The model predicts that the plasmonic coupling and scattering increases light emission by a factor of up to three compared to a flat semiconductor structure. This corresponds to reducing the absorption losses from approximately 93% in the ungrated metallic structure to 75% in the grated structure. Lower losses are associated with a significant emission enhancement enabled by the SPs of silver/GaN interfaces, which are present in the blue/green wavelength range, and can be optimized by carefully nanostructuring the metal layer and by the positioning of the QW. In general, the enhancement results from the interplay of mode scattering, conversion of SP energy directly into light, and losses in the metallic grating. The reported losses are very high when compared to the losses present in modern light-emitting diodes (LEDs). Albeit, our work provides tools needed for further optimization of plasmonic light extraction, eventually leading to highly efficient LEDs.
Quantum Evolution and Anticipation
Hans-Rudolf Thomann
2010-03-04T23:59:59.000Z
In a previous paper we have investigated quantum states evolving into mutually orthogonal states at equidistant times, and the quantum anticipation effect exhibited by measurements at one half step. Here we extend our analyzes of quantum anticipation to general type quantum evolutions and spectral measures and prove that quantum evolutions possessing an embedded orthogonal evolution are characterized by positive joint spectral measure. Furthermore, we categorize quantum evolution, assess anticipation strength and provide a framework of analytic tools and results, thus preparing for further investigation and experimental verification of anticipation in concrete physical situations such as the H-atom, which we have found to exhibit anticipation.
Internal plasma potential measurements of a Hall thruster using plasma lens focusing
Linnell, Jesse A.; Gallimore, Alec D. [Plasmadynamics and Electric Propulsion Laboratory, Department of Aerospace Engineering, University of Michigan, 1919 Green Road, Room B107, Ann Arbor, Michigan 48109 (United States)
2006-10-15T23:59:59.000Z
Magnetic field topology has been found to be a central design concern for high-efficiency Hall thrusters. For future improvements in Hall thruster design, it is necessary to better understand the effects that magnetic field topology has on the internal plasma structure. The Plasmadynamics and Electric Propulsion Laboratory's High-speed Axial Reciprocating Probe system is used in conjunction with a floating emissive probe to map the internal plasma potential structure of the NASA-173Mv1 Hall thruster [R. R. Hofer, R. S. Jankovsky, and A. D. Gallimore, J. Propul. Power 22, 721 (2006); 22, 732 (2006)]. Measurements are taken at 300 and 500 V with a xenon propellant. Electron temperature and electric field are also measured and reported. The acceleration zone and equipotential lines are found to be strongly linked to the magnetic field lines. Moreover, in some cases the ions are accelerated strongly toward the center of the discharge channel. The agreement between magnetic field lines and equipotential lines is best for high-voltage operation. These results have strong implications on the performance and lifetime optimization of Hall thrusters.
Valley pair qubits in double quantum dots of gapped graphene
G. Y. Wu; N. -Y. Lue; L. Chang
2011-07-03T23:59:59.000Z
The rise of graphene opens a new door to qubit implementation, as discussed in the recent proposal of valley pair qubits in double quantum dots of gapped graphene (Wu et al., arXiv: 1104.0443 [cond-mat.mes-hall]). The work here presents the comprehensive theory underlying the proposal. It discusses the interaction of electrons with external magnetic and electric fields in such structures. Specifically, it examines a strong, unique mechanism, i.e., the analogue of the 1st-order relativistic effect in gapped graphene. This mechanism is state mixing free and allows, together with the electrically tunable exchange coupling, a fast, all-electric manipulation of qubits via electric gates, in the time scale of ns. The work also looks into the issue of fault tolerance in a typical case, yielding at 10oK a long qubit coherence time (~O(ms)).
SCHOOL OF COMPUTING SCIENCE Exam Code Exam Name Day Exam date Time Exam Hall Hall Split
Glasgow, University of
:00 Room 601 Rankine Building COMPSCI4062_1 Cyber Security 4 Wed 07/05/2014 09:30 - 11:30 Room 201 John Mc5063_1 Cyber Security M Wed 07/05/2014 09:30 - 11:30 Fore Hall COMPSCI4014_1 CS3W:Interactive Systems 3/05/2014 09:30 - 11:30 Fore Hall COMPSCI4019_1 Distributed Algs & Systems 4 Thu 08/05/2014 14:00 - 16
A Satisficing Model for Project Selection Nicholas G. Hall ?† Zhuoyu ...
2009-12-29T23:59:59.000Z
Dec 29, 2009 ... plemented by maximizing the entropic satisficing measure. Thus, our ...... Using the guidelines of Hall and Posner (2001), (a) we generate a ...
Rebuilding It Better: Greensburg, Kansas. City Hall (Brochure)
Not Available
2010-04-01T23:59:59.000Z
This document showcases the LEED-Platinum designed Greensburg City Hall, which was rebuilt green, after a massive tornado destroyed Greensburg, Kansas in May 2007.
Rebuilding It Better: Greensburg, Kansas, City Hall (Brochure)
Not Available
2010-09-01T23:59:59.000Z
This brochure details the energy efficient and sustainable aspects of the LEED Platinum-designated City Hall building in Greensburg, Kansas.
Rebuilding It Better: Greensburg, Kansas. City Hall (Brochure)
Office of Energy Efficiency and Renewable Energy (EERE)
This brochure details the energy efficient and sustainable aspects of the LEED Platinum-designated City Hall building in Greensburg, Kansas.
Schedule and cost estimate for an innovative Boston Harbor concert hall
Coste, Amelie, 1982-
2004-01-01T23:59:59.000Z
This thesis formulates a cost estimate and schedule for constructing the Boston Concert Hall, an innovative hypothetical building composed of two concert halls and a restaurant. Concert Halls are complex and expensive ...
Oshmyansky, A
2007-01-01T23:59:59.000Z
An alternative quantum field theory for gravity is proposed for low energies based on an attractive effect between contaminants in a Bose-Einstein Condensate rather than on particle exchange. In the ``contaminant in condensate effect," contaminants cause a potential in an otherwise uniform condensate, forcing the condensate between two contaminants to a higher energy state. The energy of the system decreases as the contaminants come closer together, causing an attractive force between contaminants. It is proposed that mass-energy may have a similar effect on Einstein's space-time field, and gravity is quantized by the same method by which the contaminant in condensate effect is quantized. The resulting theory is finite and, if a physical condensate is assumed to underly the system, predictive. However, the proposed theory has several flaws at high energies and is thus limited to low energies. Falsifiable predictions are given for the case that the Higgs condensate is assumed to be the condensate underlying gr...
Alexander Oshmyansky
2007-03-08T23:59:59.000Z
An alternative quantum field theory for gravity is proposed for low energies based on an attractive effect between contaminants in a Bose-Einstein Condensate rather than on particle exchange. In the ``contaminant in condensate effect," contaminants cause a potential in an otherwise uniform condensate, forcing the condensate between two contaminants to a higher energy state. The energy of the system decreases as the contaminants come closer together, causing an attractive force between contaminants. It is proposed that mass-energy may have a similar effect on Einstein's space-time field, and gravity is quantized by the same method by which the contaminant in condensate effect is quantized. The resulting theory is finite and, if a physical condensate is assumed to underly the system, predictive. However, the proposed theory has several flaws at high energies and is thus limited to low energies. Falsifiable predictions are given for the case that the Higgs condensate is assumed to be the condensate underlying gravity.
Salvagnini, Elena [UZ Gasthuisberg, Medical Imaging Research Center and Department of Radiology, Herestraat 49, B-3000 Leuven, Belgium and SCK-CEN, Boeretang 200, B-2400 Mol (Belgium)] [UZ Gasthuisberg, Medical Imaging Research Center and Department of Radiology, Herestraat 49, B-3000 Leuven, Belgium and SCK-CEN, Boeretang 200, B-2400 Mol (Belgium); Bosmans, Hilde; Marshall, Nicholas W. [UZ Gasthuisberg, Medical Imaging Research Center and Department of Radiology, Herestraat 49, B-3000 Leuven (Belgium)] [UZ Gasthuisberg, Medical Imaging Research Center and Department of Radiology, Herestraat 49, B-3000 Leuven (Belgium); Struelens, Lara [SCK-CEN, Boeretang 200, B-2400 Mol (Belgium)] [SCK-CEN, Boeretang 200, B-2400 Mol (Belgium)
2013-10-15T23:59:59.000Z
Purpose: The aim of this paper was to illustrate the value of the new metric effective detective quantum efficiency (eDQE) in relation to more established measures in the optimization process of two digital mammography systems. The following metrics were included for comparison against eDQE: detective quantum efficiency (DQE) of the detector, signal difference to noise ratio (SdNR), and detectability index (d?) calculated using a standard nonprewhitened observer with eye filter.Methods: The two systems investigated were the Siemens MAMMOMAT Inspiration and the Hologic Selenia Dimensions. The presampling modulation transfer function (MTF) required for the eDQE was measured using two geometries: a geometry containing scattered radiation and a low scatter geometry. The eDQE, SdNR, and d? were measured for poly(methyl methacrylate) (PMMA) thicknesses of 20, 40, 60, and 70 mm, with and without the antiscatter grid and for a selection of clinically relevant target/filter (T/F) combinations. Figures of merit (FOMs) were then formed from SdNR and d? using the mean glandular dose as the factor to express detriment. Detector DQE was measured at energies covering the range of typical clinically used spectra.Results: The MTF measured in the presence of scattered radiation showed a large drop at low spatial frequency compared to the low scatter method and led to a corresponding reduction in eDQE. The eDQE for the Siemens system at 1 mm{sup ?1} ranged between 0.15 and 0.27, depending on T/F and grid setting. For the Hologic system, eDQE at 1 mm{sup ?1} varied from 0.15 to 0.32, again depending on T/F and grid setting. The eDQE results for both systems showed that the grid increased the system efficiency for PMMA thicknesses of 40 mm and above but showed only small sensitivity to T/F setting. While results of the SdNR and d? based FOMs confirmed the eDQE grid position results, they were also more specific in terms of T/F selection. For the Siemens system at 20 mm PMMA, the FOMs indicated Mo/Mo (grid out) as optimal while W/Rh (grid in) was the optimal configuration at 40, 60, and 70 mm PMMA. For the Hologic, the FOMs pointed to W/Rh (grid in) at 20 and 40 mm of PMMA while W/Ag (grid in) gave the highest FOM at 60 and 70 mm PMMA. Finally, DQE at 1 mm{sup ?1} averaged for the four beam qualities studied was 0.44 ± 0.02 and 0.55 ± 0.03 for the Siemens and Hologic detectors, respectively, indicating only a small influence of energy on detector DQE.Conclusions: Both the DQE and eDQE data showed only a small sensitivity to T/F setting for these two systems. The eDQE showed clear preferences in terms of scatter reduction, being highest for the grid-in geometry for PMMA thicknesses of 40 mm and above. The SdNR and d? based figures of merit, which contain additional weighting for contrast and dose, pointed to specific T/F settings for both systems.
Model checking quantum Markov chains
Yuan Feng; Nengkun Yu; Mingsheng Ying
2013-11-14T23:59:59.000Z
Although the security of quantum cryptography is provable based on the principles of quantum mechanics, it can be compromised by the flaws in the design of quantum protocols and the noise in their physical implementations. So, it is indispensable to develop techniques of verifying and debugging quantum cryptographic systems. Model-checking has proved to be effective in the verification of classical cryptographic protocols, but an essential difficulty arises when it is applied to quantum systems: the state space of a quantum system is always a continuum even when its dimension is finite. To overcome this difficulty, we introduce a novel notion of quantum Markov chain, specially suited to model quantum cryptographic protocols, in which quantum effects are entirely encoded into super-operators labelling transitions, leaving the location information (nodes) being classical. Then we define a quantum extension of probabilistic computation tree logic (PCTL) and develop a model-checking algorithm for quantum Markov chains.
Model checking quantum Markov chains
Feng, Yuan; Ying, Mingsheng
2012-01-01T23:59:59.000Z
Although the security of quantum cryptography is provable based on the principles of quantum mechanics, it can be compromised by the flaws in the design of quantum protocols and the noise in their physical implementations. So, it is indispensable to develop techniques of verifying and debugging quantum cryptographic systems. Model-checking has proved to be effective in the verification of classical cryptographic protocols, but an essential difficulty arises when it is applied to quantum systems: the state space of a quantum system is always a continuum even when its dimension is finite. To overcome this difficulty, we introduce a novel notion of quantum Markov chain, specially suited to model quantum cryptographic protocols, in which quantum effects are entirely encoded into super-operators labelling transitions, leaving the location information (nodes) being classical. Then we define a quantum extension of probabilistic computation tree logic (PCTL) and develop a model-checking algorithm for quantum Markov c...
K. -S. Park; H. Han
2011-05-31T23:59:59.000Z
Making use of index theorem and spin Chern Simons theory, we construct an effective topological field theory of strongly correlated topological insulators coupling to a nonabelian gauge field $ SU(N) $ with an interaction constant $ g $ in the absence of the time-reversal symmetry breaking. If $ N $ and $ g $ allow us to define a t'Hooft parameter $ \\lambda $ of effective coupling as $ \\lambda = N g^{2} $, then our construction leads to the fractional quantum Hall effect on the surface with Hall conductance $ \\sigma_{H}^{s} = \\frac{1}{4\\lambda} \\frac{e^{2}}{h} $. For the magnetoelectric response described by a bulk axion angle $ \\theta $, we propose that the fractional magnetoelectric effect can be realized in gapped time reversal invariant topological insulators of strongly correlated bosons or fermions with an effective axion angle $ \\theta_{eff} = \\frac{\\pi}{2 \\lambda} $ if they can have fractional excitations and degenerate ground states on topologically nontrivial and oriented spaces. Provided that an effective charge is given by $ e_{eff} = \\frac{e}{\\sqrt{2 \\lambda}} $, it is shown that $ \\sigma_{H}^{s} = \\frac{e_{eff}^{2}}{2h} $, resulting in a surface Hall conductance of gapless fermions with $ e_{eff} $ and a pure axion angle $ \\theta = \\pi $.
Quantum Physics and Nanotechnology
Vladimir K. Nevolin
2011-06-06T23:59:59.000Z
Experimental studies of infinite (unrestricted at least in one direction) quantum particle motion using probe nanotechnologies have revealed the necessity of revising previous concepts of their motion. Particularly, quantum particles transfer quantum motion nonlocality energy beside classical kinetic energy, in other words, they are in two different kinds of motion simultaneously. The quantum component of the motion energy may be quite considerable under certain circumstances. Some new effects were predicted and proved experimentally in terms of this phenomenon. A new prototype refrigerating device was tested, its principle of operation being based on the effect of transferring the quantum component of the motion energy.
On quantum effects in the vicinity of would-be horizons
P. Marecki
2006-12-28T23:59:59.000Z
We present a method based on the so-called Quantum Energy Inequalities, which allows to compare, and bound, the expectation values of energy-densities of ground states of quantum fields in spacetimes possessing isometric regions. The method supports the conclusion, that the Boulware energy density is universal both: at modest (and far) distances from compact spherical objects, and close to the would-be horizons of the gravastar/QBHO spacetimes. It also provides a natural consistency check for concrete (approximate, numerical) calculations of the expectation values of the energy-momentum tensors.
Bernhard Mecking steps down as Hall B leader at Jefferson Lab...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Bernhard Mecking Jefferson Lab staff scientist Bernhard Mecking with the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B. Bernhard Mecking steps down as Hall B leader at...
Hamerschlag Hall Green Roof Storm Water Retention and Runoff Reduction Performance Lucheng Chen
Andrews, Peter B.
Hamerschlag Hall Green Roof Storm Water Retention and Runoff Reduction Performance ......................................................................................................................... 2 2. Hamerschlag Hall Green Roof .............................................................................. 13 4. Methods of Storm Analysis and Green Roof Performance Analysis
Quantum Effects on all Lagrangian Points and Prospects to Measure Them in the Earth-Moon System
Emmanuele Battista; Giampiero Esposito; Simone Dell' Agnello; Jules Simo
2015-06-16T23:59:59.000Z
The one-loop long distance quantum corrections to the Newtonian potential imply tiny but observable effects in the restricted three-body problem of celestial mechanics, i.e., both at the Lagrangian points of stable equilibrium and at those of unstable equilibrium the Newtonian values of planetoid's coordinates are changed by a few millimetres in the Earth-Moon system. First, we find that the equations governing the position of both noncollinear and collinear quantum libration points are algebraic fifth degree and ninth degree equations, respectively. Second, we discuss the prospects to measure, with the help of laser ranging, the above departure from the equilateral triangle picture, which is a challenging task. On the other hand, a modern version of the planetoid is the solar sail, and much progress has been made, in recent years, on the displaced periodic orbits of solar sails at all libration points. By taking into account the quantum corrections to the Newtonian potential, displaced periodic orbits of the solar sail at libration points are again found to exist.
Nonlinear friction in quantum mechanics
Roumen Tsekov
2013-03-10T23:59:59.000Z
The effect of nonlinear friction forces in quantum mechanics is studied via dissipative Madelung hydrodynamics. A new thermo-quantum diffusion equation is derived, which is solved for the particular case of quantum Brownian motion with a cubic friction. It is extended also by a chemical reaction term to describe quantum reaction-diffusion systems with nonlinear friction as well.
Hypernuclear spectroscopy program at JLab Hall C
Hashimoto, Osamu; Hashimoto, Osamu; Nakamura, Satoshi; Acha Quimper, Armando; Ahmidouch, Abdellah; Androic, Darko; Asaturyan, Arshak; Asaturyan, Razmik; Baker, O.; Baturin, Pavlo; Benmokhtar, Fatiha; Bosted, Peter; Carlini, Roger; Chen, X.; Christy, Michael; Cole, Leon; Danagoulian, Samuel; Daniel, AJI; Dharmawardane, Kahanawita; Egiyan, Kim; Elaasar, Mostafa; Ent, Rolf; Fenker, Howard; Fujii, Yu; Furic, Miroslav; Gan, Liping; Gaskell, David; Gasparian, Ashot; Gibson, Edward; Gueye, Paul; Halkyard, Rebekah; Honda, D.; Horn, Tanja; Hu, Bitao; Hu, S.; Hungerford, Ed; Ispiryan, Mikayel; Johnston, Kathleen; Jones, Mark; Kalantarians, Narbe; Kaneta, M.; Kato, F.; Kato, Seigo; Kawama, Daisuke; Keppel, Cynthia; Li, Ya; Luo, Wei; Mack, David; Margaryan, Amur; Marikyan, Gagik; Maruyama, Nayuta; Matsumura, Akihiko; Miyoshi, Toshinobu; Mkrtchyan, Arthur; Mkrtchyan, Hamlet; Navasardyan, Tigran; Niculescu, Gabriel; Niculescu, Maria-Ioana; Nomura, Hiroshi; Nonaka, Kenichi; Ohtani, Atsushi; Okayasu, Yuichi; Pamela, Priscilla; Perez, Naipy; Petkovic, Tomislav; Randeniya, Kapugodage; Reinhold, Joerg; Rivera Castillo, Roberto; Roche, Julie; Rodriguez, Victor; Sato, Yoshinori; Seva, Tomislav; Tang, Liguang; Simicevic, Neven; Smith, Gregory; Sumihama, Mizuki; Song, Y.; Tadevosyan, Vardan; Takahashi, Toshiyuki; Tamura, Hirokazu; Tvaskis, Vladas; Vulcan, William; Wang, B.; Wells, Steven; Yan, Chen; Yuan, Lulin; Zamkochian, S.
2008-05-01T23:59:59.000Z
DOI: http://dx.doi.org/10.1016/j.nuclphysa.2008.01.029
Hypernuclear production by the (e,e?K+) reaction has unique advantages in hypernuclear spectroscopy of the S=?1 regime. The second-generation spectroscopy experiment on 12C, 7Li and 28Si targets has been recently carried out at JLab Hall C with a new experimental configuration (Tilt method) and also using a new high-resolution kaon spectrometer (HKS). The experiment is described and preliminary results are presented together with the empasis of significance of the (e,e?K+) reaction for ? hypernuclear spectroscopy and its future prospects.
Hypernuclei in Hall C | Jefferson Lab
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
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Anthony Kathryn Hall | Open Energy Information
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Shi, Y L; Wu, J X; Zhu, C J; Xu, J P; Yang, Y P
2015-01-01T23:59:59.000Z
We examine a Kerr phase gate in a semiconductor quantum well structure based on the tunnelling interference effect. We show that there exist a specific signal field detuning, at which the absorption/amplification of the probe field will be eliminated with the increase of the tunnelling interference. Simultaneously, the probe field will acquire a -\\pi phase shift at the exit of the medium. We demonstrate with numerical simulations that a complete 180^\\circ phase rotation for the probe field at the exit of the medium is achieved, which may result in many applications in information science and telecommunication.
Effect of the (OH) Surface Capping on ZnO Quantum Dots
Nabben, Reinhard
in air at different temperatures from 150500 C for 30 min. In comparison, highly purified bulk Zn is related to oxygen deficiency [1]; the other is a much narrower ultraviolet (UV) emission band at around, compared with good quality ZnO single crystals or ZnO powders, the UV bandgap luminescence in quantum dots
Quantum corrections and bound-state effects in the energy relaxation of hot dense Hydrogen
M. W. C. Dharma-Wardana
2008-04-13T23:59:59.000Z
Simple analytic formulae for energy relaxation (ER) in electron-ion systems, with quantum corrections, ion dynamics and RPA-type screening are presented. ER in the presence of bound electrons is examined in view of of recent simulations for ER in hydrogen in the range 10^{20}-10^{24} electrons/cc.
Hamerschlag Hall Green Roof Project Water Monitoring System
Andrews, Peter B.
1 Hamerschlag Hall Green Roof Project Water Monitoring System Plans and Specifications Created By: David Carothers Date: 2/17/05 #12;2 Hamerschlag Hall Green Roof Project Date: 2/14/05 Created By: David and the flumes shall be water tight. (Figures 1&2) · The connection between the flume and the green roof membrane
413 South Hall Bowling Green, OH 43403-0185
Moore, Paul A.
(Street, City, State, and Zip Code): I , a student at Bowling Green State University give permission413 South Hall Bowling Green, OH 43403-0185 Phone 419-372-8495, TTY 419-372-9455 Fax 419 with specific test results or clinical observations. #12;Page 2 of 4 413 South Hall Bowling Green, OH 43403
RCP Spring 2011 SPONSORS MEETING PETROLEUM HALL, GREEN CENTER
RCP Spring 2011 SPONSORS MEETING PETROLEUM HALL, GREEN CENTER Colorado School of Mines Â Friedhoff Hall (Lower Level of Green Center) 1:00 - 2:30 PM Postle Field Reservoir Characterization and Pouce Coupe Fields: Matt Billingsley, CSM and Jared Atkinson, Talisman Energy 3:45 - 5:00 PM
Sinitsyn, NA; Hankiewicz, EM; Teizer, Winfried; Sinova, Jairo.
2004-01-01T23:59:59.000Z
new avenues in spintronics research and transport phenomena which may meet the first challenge. The intrinsic spin-Hall effect consists of a dissipationless spin-current contribution generated perpendicular to the driv- ing electric field whenever... that the dc z-component spin-current Hall response to a driv- ing internal electric field, jsz=sxyspinEy, in the clean limit has a universal value whenever the two Rashba split bands are occupied (the usual case), sxyspin=e /8p, and vanishes linearly...
Undulator Hall Air Temperature Fault Scenarios
Sevilla, J.; Welch, J.; /SLAC; ,
2010-11-17T23:59:59.000Z
Recent experience indicates that the LCLS undulator segments must not, at any time following tuning, be allowed to change temperature by more than about {+-}2.5 C or the magnetic center will irreversibly shift outside of acceptable tolerances. This vulnerability raises a concern that under fault conditions the ambient temperature in the Undulator Hall might go outside of the safe range and potentially could require removal and retuning of all the segments. In this note we estimate changes that can be expected in the Undulator Hall air temperature for three fault scenarios: (1) System-wide power failure; (2) Heating Ventilation and Air Conditioning (HVAC) system shutdown; and (3) HVAC system temperature regulation fault. We find that for either a system-wide power failure or an HVAC system shutdown (with the technical equipment left on), the short-term temperature changes of the air would be modest due to the ability of the walls and floor to act as a heat ballast. No action would be needed to protect the undulator system in the event of a system-wide power failure. Some action to adjust the heat balance, in the case of the HVAC power failure with the equipment left on, might be desirable but is not required. On the other hand, a temperature regulation failure of the HVAC system can quickly cause large excursions in air temperature and prompt action would be required to avoid damage to the undulator system.
Cylindrical Hall Thrusters with Permanent Magnets
Raitses, Yevgeny; Merino, Enrique; Fisch, Nathaniel J.
2010-10-18T23:59:59.000Z
The use of permanent magnets instead of electromagnet coils for low power Hall thrusters can offer a significant reduction of both the total electric power consumption and the thruster mass. Two permanent magnet versions of the miniaturized cylindrical Hall thruster (CHT) of different overall dimensions were operated in the power range of 50W-300 W. The discharge and plasma plume measurements revealed that the CHT thrusters with permanent magnets and electromagnet coils operate rather differently. In particular, the angular ion current density distribution from the permanent magnet thrusters has an unusual halo shape, with a majority of high energy ions flowing at large angles with respect to the thruster centerline. Differences in the magnetic field topology outside the thruster channel and in the vicinity of the channel exit are likely responsible for the differences in the plume characteristics measured for the CHTs with electromagnets and permanent magnets. It is shown that the presence of the reversing-direction or cusp-type magnetic field configuration inside the thruster channel without a strong axial magnetic field outside the thruster channel does not lead to the halo plasma plume from the CHT. __________________________________________________
Trajectories without quantum uncertainties
Eugene S. Polzik; Klemens Hammerer
2014-05-13T23:59:59.000Z
A common knowledge suggests that trajectories of particles in quantum mechanics always have quantum uncertainties. These quantum uncertainties set by the Heisenberg uncertainty principle limit precision of measurements of fields and forces, and ultimately give rise to the standard quantum limit in metrology. With the rapid developments of sensitivity of measurements these limits have been approached in various types of measurements including measurements of fields and acceleration. Here we show that a quantum trajectory of one system measured relatively to the other "reference system" with an effective negative mass can be quantum uncertainty--free. The method crucially relies on the generation of an Einstein-Podolsky-Rosen entangled state of two objects, one of which has an effective negative mass. From a practical perspective these ideas open the way towards force and acceleration measurements at new levels of sensitivity far below the standard quantum limit.
Davies, M. J., E-mail: Matthew.Davies-2@Manchester.ac.uk; Dawson, P. [School of Physics and Astronomy, Photon Science Institute, University of Manchester, Manchester M13 9PL (United Kingdom); Massabuau, F. C.-P.; Oliver, R. A.; Kappers, M. J.; Humphreys, C. J. [Department of Material Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)
2014-09-01T23:59:59.000Z
In this paper, we report on the effects of including Si-doped (In)GaN prelayers on the low temperature optical properties of a blue-light emitting InGaN/GaN single quantum well. We observed a large blue shift of the photoluminescence peak emission energy and significant increases in the radiative recombination rate for the quantum well structures that incorporated Si-doped prelayers. Simulations of the variation of the conduction and valence band energies show that a strong modification of the band profile occurs for the quantum wells on Si-doped prelayers due to an increase in strength of the surface polarization field. The enhanced surface polarization field opposes the built-in field across the quantum well and thus reduces this built-in electric field. This reduction of the electric field across the quantum well reduces the Quantum Confined Stark Effect and is responsible for the observed blue shift and the change in the recombination dynamics.
Band filling effects on temperature performance of intermediate band quantum wire solar cells
Kunets, Vas. P., E-mail: vkunets@uark.edu; Furrow, C. S.; Ware, M. E.; Souza, L. D. de; Benamara, M.; Salamo, G. J. [Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Mortazavi, M. [Department of Chemistry and Physics, University of Arkansas at Pine Bluff, Pine Bluff, Arkansas 71601 (United States)
2014-08-28T23:59:59.000Z
Detailed studies of solar cell efficiency as a function of temperature were performed for quantum wire intermediate band solar cells grown on the (311)A plane. A remotely doped one-dimensional intermediate band made of self-assembled In{sub 0.4}Ga{sub 0.6}As quantum wires was compared to an undoped intermediate band and a reference p-i-n GaAs sample. These studies indicate that the efficiencies of these solar cells depend on the population of the one-dimensional band by equilibrium free carriers. A change in this population by free electrons under various temperatures affects absorption and carrier transport of non-equilibrium carriers generated by incident light. This results in different efficiencies for both the doped and undoped intermediate band solar cells in comparison with the reference GaAs p-i-n solar cell device.
Effect of Monolayer Thickness Fluctuations on Coherent Exciton Coupling in Single Quantum Wells
Yuri D. Glinka; Zheng Sun; Mikhail Erementchouk; Michael N. Leuenberger; Alan D. Bristow; Steven T. Cundiff; Allan S. Bracker; Xiaoqin Li
2012-10-04T23:59:59.000Z
Monolayer fluctuations in the thickness of a semiconductor quantum well (QW) lead to three types of excitons, located in the narrower, average and thicker regions of the QW, which are clearly resolved in optical spectra. Whether or not these excitons are coherently coupled via Coulomb interactions is a long-standing debate. We demonstrate that different types of disorder in QWs distinctly affects the coherent coupling and that the coupling strength can be quantitatively measured using optical two-dimensional Fourier transform spectroscopy. We prove experimentally and theoretically that in narrow quantum wells the coherent coupling occurs predominantly between excitons residing in the disorder-free areas of the QWs and those residing in the plateau-type disorder. In contrast, excitons localized in the fault-type disorder potentials do not coherently couple to other excitons.
Effects of time delay in feedback control of linear quantum systems
Kazunori Nishio; Kenji Kashima; Jun-ichi Imura
2008-11-27T23:59:59.000Z
We investigate feedback control of linear quantum systems subject to feedback-loop time delays. In particular, we examine the relation between the potentially achievable control performance and the time delays, and provide theoretical guidelines for the future experimental setup in two physical systems, which are typical in this research field. The evaluation criterion for the analysis is given by the optimal control performance formula, the derivation of which is from the classical control theoretic results about the input-output delay systems.
Gaigalas, Gediminas; Gaidamauskas, Erikas; Rudzikas, Zenonas; Magnani, Nicola; Caciuffo, Roberto [Vilnius University Research Institute of Theoretical Physics and Astronomy, A. Gostauto 12, LT-01108 Vilnius (Lithuania); European Commission, Joint Research Centre, Institute for Transuranium Elements, Postfach 2340, D-76125 Karlsruhe (Germany)
2010-02-15T23:59:59.000Z
Large-scale multiconfiguration Dirac-Fock calculations have been performed for the superheavy element eka-thorium, Z=122. The resulting atomic structure is compared with that obtained by various computational approaches involving different degrees of approximation in order to elucidate the role that correlation, relativistic, Breit, and quantum electrodynamics corrections play in determining the low-energy atomic spectrum. The accuracy of the calculations is assessed by comparing theoretical results obtained for thorium with available experimental data.
Physics 5614 Spring 2005 Introduction to Quantum Electronics
Heflin, Randy
122 Robeson Hall Texts : Quantum Electronics, A. Yariv, 3rd ed. (will be given as hand-outs) Nonlinear Optics, R. W. Boyd Instructor : Prof. R. Heflin, Room 108A Robeson, ext. 1-4504 Office Hours : M 11 throughout the semester. Grades : 80% Homework 20% Research Paper (more details later) Chap. Title From Yariv
Global quantum discord and quantum phase transition in XY model
Si-Yuan Liu; Yu-Ran Zhang; Wen-Li Yang; Heng Fan
2014-05-20T23:59:59.000Z
We study the relationship between the behavior of global quantum correlations and quantum phase transitions in XY model. We find that the two kinds of phase transitions in the studied model can be characterized by the features of global quantum discord (GQD) and the corresponding quantum correlations. We demonstrate that the maximum of the sum of all the nearest neighbor bipartite GQDs is effective and accurate for signaling the Ising quantum phase transition, in contrast, the sudden change of GQD is very suitable for characterizing another phase transition in the XY model. This may shed lights on the study of properties of quantum correlations in different quantum phases.
Dry Dilution Refrigerator for Experiments on Quantum Effects in the Microwave Regime
Marx, A; Uhlig, K
2014-01-01T23:59:59.000Z
At the Walther-Mei{\\ss}ner-Institut (WMI), a new cryogen-free 3He/4He dilution refrigerator (DR) has been completed; the cryostat will be employed to cool experiments on superconducting quantum circuits for quantum information technology and quantum simulations. All major components have been made at the WMI. The DR offers lots of space at the various stages of the apparatus for microwave components and cables. E. g., the usable space at the mixing chamber has a height of more than 60 cm and a diameter of 30 cm (mixing chamber mounting plate). To cool cables and cold amplifiers, the DR is equipped with a separate 4He-1K-loop which offers a cooling power of up to 100 mW near 1K. The refrigeration power of the still is 18 mW at 0.9 K; the diameter of its mounting plate is 35 cm. The cryostat rests in an aluminum trestle on air springs to attenuate building vibrations. It is precooled by a Cryomech PT410-RM pulse tube cryocooler (PTC) which is mechanically decoupled from the vacuum can of the cryostat by a bello...
Building Codes for Classrooms 34MK 3401 Market Street JMHH Jon M. Huntsman Hall
Plotkin, Joshua B.
Building Codes for Classrooms 34MK 3401 Market Street JMHH Jon M. Huntsman Hall 35MK 3550 Market Market Street KWH Kelly Writers House ACHM Anatomy/Chemistry Building L-FH Lauder-Fischer Hall ADDM Fisher-Bennett Hall LIPP Lippincott BLOC Blockley Hall LLAB Leidy Labs CAST Caster Building LRSM Lab
Magnetic shielding of the channel walls in a Hall plasma accelerator
Mikellides, Ioannis G.; Katz, Ira; Hofer, Richard R.; Goebel, Dan M. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States); Grys, Kristi de; Mathers, Alex [Aerojet, Redmond, Washington 98052 (United States)
2011-03-15T23:59:59.000Z
In a qualification life test of a Hall thruster it was found that the erosion of the acceleration channel practically stopped after {approx}5600 h. Numerical simulations using a two-dimensional axisymmetric plasma solver with a magnetic field-aligned mesh reveal that when the channel receded from its early-in-life to its steady-state configuration the following changes occurred near the wall: (1) reduction of the electric field parallel to the wall that prohibited ions from acquiring significant impact kinetic energy before entering the sheath, (2) reduction of the potential fall in the sheath that further diminished the total energy ions gained before striking the material, and (3) reduction of the ion number density that decreased the flux of ions to the wall. All these changes, found to have been induced by the magnetic field, constituted collectively an effective shielding of the walls from any significant ion bombardment. Thus, we term this process in Hall thrusters 'magnetic shielding'.
Sassoli de Bianchi, Massimiliano, E-mail: autoricerca@gmail.com
2013-09-15T23:59:59.000Z
In a letter to Born, Einstein wrote [42]: “Quantum mechanics is certainly imposing. But an inner voice tells me that it is not yet the real thing. The theory says a lot, but does not really bring us any closer to the secret of the ‘old one.’ I, at any rate, am convinced that He does not throw dice.” In this paper we take seriously Einstein’s famous metaphor, and show that we can gain considerable insight into quantum mechanics by doing something as simple as rolling dice. More precisely, we show how to perform measurements on a single die, to create typical quantum interference effects, and how to connect (entangle) two identical dice, to maximally violate Bell’s inequality. -- Highlights: •Rolling a die is a quantum process admitting a Hilbert space representation. •Rolling experiments with a single die can produce interference effects. •Two connected dice can violate Bell’s inequality. •Correlations need to be created by the measurement, to violate Bell’s inequality.
Micro-Hall position sensing of magnetic nanowires.
Mihajlovic, G.; Hoffmann, A.; von Molnar, S.; Materials Science Division; Florida State Univ.
2009-01-01T23:59:59.000Z
The Hall voltage output of a micro-Hall magnetic sensor depends on the relative position of a magnetic nanowire with respect to its sensing area. Following this idea, we performed analytical calculations which show that, under certain conditions, these devices can track the position of a magnetic nanowire with subnanometer resolution. Our results suggest that micro-Hall sensors can be utilized to provide a direct electronic readout of the position of magnetic nanowires in their applications as biomolecular manipulators or dynamic components in micro- and nanoscale devices.
Kanematsu, Yusuke; Tachikawa, Masanori [Quantum Chemistry Division, Yokohama City University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027 (Japan)] [Quantum Chemistry Division, Yokohama City University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027 (Japan)
2014-04-28T23:59:59.000Z
We have developed the multicomponent hybrid density functional theory [MC-(HF+DFT)] method with polarizable continuum model (PCM) for the analysis of molecular properties including both nuclear quantum effect and solvent effect. The chemical shifts and H/D isotope shifts of the picolinic acid N-oxide (PANO) molecule in chloroform and acetonitrile solvents are applied by B3LYP electron exchange-correlation functional for our MC-(HF+DFT) method with PCM (MC-B3LYP/PCM). Our MC-B3LYP/PCM results for PANO are in reasonable agreement with the corresponding experimental chemical shifts and isotope shifts. We further investigated the applicability of our method for acetylacetone in several solvents.
Buckled nano rod - a two state system: quantum effects on its dynamics
Aniruddha Chakraborty
2011-07-18T23:59:59.000Z
We consider a suspended elastic rod under longitudinal compression. The compression can be used to adjust potential energy for transverse displacements from harmonic to double well regime. The two minima in potential energy curve describe two possible buckled states. Using transition state theory (TST) we have calculated the rate of conversion from one state to other. If the strain $\\epsilon = 4 \\epsilon_c$ the simple TST rate diverges. We suggest a method to correct this divergence for quantum calculations. We also find that zero point energy contributions can be quite large so that single mode calculations can lead to large errors in the rate.
On description of quantum plasma
S. V. Vladimirov; Yu. O. Tyshetskiy
2011-01-21T23:59:59.000Z
A plasma becomes quantum when the quantum nature of its particles significantly affects its macroscopic properties. To answer the question of when the collective quantum plasma effects are important, a proper description of such effects is necessary. We consider here the most common methods of description of quantum plasma, along with the related assumptions and applicability limits. In particular, we analyze in detail the hydrodynamic description of quantum plasma, as well as discuss some kinetic features of analytic properties of linear dielectric response function in quantum plasma. We point out the most important, in our view, fundamental problems occurring already in the linear approximation and requiring further investigation. (submitted to Physics-Uspekhi)
Ganguly, A.; Haldar, A.; Sinha, J.; Barman, A., E-mail: abarman@bose.res.in, E-mail: del.atkinson@durham.ac.uk [Thematic Unit of Excellence on Nanodevice Technology, Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Kolkata 700098 (India); Rowan-Robinson, R. M.; Jaiswal, S.; Hindmarch, A. T.; Atkinson, D. A., E-mail: abarman@bose.res.in, E-mail: del.atkinson@durham.ac.uk [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)
2014-09-15T23:59:59.000Z
The effect of spin torque from the spin Hall effect in Pt/Ni{sub 81}Fe{sub 19} rectangular bilayer film was investigated using time-resolved magneto-optical Kerr microscopy. Current flow through the stack resulted in a linear variation of effective damping up to ±7%, attributed to spin current injection from the Pt into the Ni{sub 81}Fe{sub 19}. The spin Hall angle of Pt was estimated as 0.11?±?0.03. The modulation of the damping depended on the angle between the current and the bias magnetic field. These results demonstrate the importance of optical detection of precessional magnetization dynamics for studying spin transfer torque due to spin Hall effect.
Superradiant Quantum Heat Engine
Ali Ü. C. Hardal; Özgür E. Müstecapl?oglu
2015-04-22T23:59:59.000Z
Quantum physics revolutionized classical disciplines of mechanics, statistical physics, and electrodynamics. One branch of scientific knowledge however seems untouched: thermodynamics. Major motivation behind thermodynamics is to develop efficient heat engines. Technology has a trend to miniaturize engines, reaching to quantum regimes. Development of quantum heat engines (QHEs) requires emerging field of quantum thermodynamics. Studies of QHEs debate whether quantum coherence can be used as a resource. We explore an alternative where it can function as an effective catalyst. We propose a QHE which consists of a photon gas inside an optical cavity as the working fluid and quantum coherent atomic clusters as the fuel. Utilizing the superradiance, where a cluster can radiate quadratically faster than a single atom, we show that the work output becomes proportional to the square of the number of the atoms. In addition to practical value of cranking up QHE, our result is a fundamental difference of a quantum fuel from its classical counterpart.
accelerator laboratory hall: Topics by E-print Network
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Halls Summer Residential Plasma Physics and Fusion Websites Summary: - youth playing sand volleyball or doing sidewalk chalk, picnic set-up at Adams or Ogg) ...and the most,000....
Norm G. Hall Western Australian Marine Research laboratories
Norm G. Hall Western Australian Marine Research laboratories Perth, Western Australia 6020, Western Australia. 61 50. Australia Ian C. Potter* School of Biological and Environmental Sciences, Murdoch University. Murdoch, Western Australia. 6 J50, Australia Comparisons between generalized growth
Replies to Weatherson, Hall, and Lange Michael Strevens
Strevens, Michael
; in what follows, I hope to show that Hall's and Lange's contributions as well amount not only to worthy of the outcomes of auctions of oil drilling rights in the Gulf of Mexico, provides a perfect illustration
Theoretical and experimental investigation of Hall thruster miniaturization
Warner, Noah Zachary, 1978-
2007-01-01T23:59:59.000Z
Interest in small-scale space propulsion continues to grow with the increasing number of small satellite missions, particularly in the area of formation flight. Miniaturized Hall thrusters have been identified as a candidate ...
Hall viscosity and angular momentum in gapless holographic models
Liu, Hong
We use the holographic approach to compare the Hall viscosity ?[subscript H] and the angular momentum density J in gapless systems in 2 + 1 dimensions at finite temperature. We start with a conformal fixed point and turn ...
TBH-0042- In the Matter of Curtis Hall
Broader source: Energy.gov [DOE]
This Initial Agency Decision involves a whistleblower complaint filed by Mr. Curtis Hall (also referred to as the complainant or the individual) under the Department of Energy (DOE) Contractor...
Sun, X.; Dresselhaus, M.S.; Wang, K.L.; Tanner, M.O.
1997-07-01T23:59:59.000Z
The Si/Si{sub 1{minus}x}Ge{sub x} quantum well system is attractive for high temperature thermoelectric applications and for demonstration of proof-of-principle for enhanced thermoelectric figure of merit Z, since the interfaces and carrier densities can be well controlled in this system. The authors report here theoretical calculations for Z in this system, and results from theoretical modeling of quantum confinement effects in the presence of {delta}-doping within the barrier layers. The {delta}-doping layers are introduced by growing very thin layers of wide band gap materials within the barrier layers in order to increase the effective barrier height within the barriers and thereby reduce the barrier width necessary for the quantum confinement of carriers within the quantum well. The overall figure of merit is thereby enhanced due to the reduced barrier width and hence reduced thermal conductivity, {kappa}. The {delta}-doping should further reduce {kappa} in the barriers by introducing phonon scattering centers within the barrier region. The temperature dependence of Z for Si quantum wells is also discussed.
Jeans instability in a quantum dusty magnetoplasma
Salimullah, M. [Department of Physics, GC University, Lahore-54000 (Pakistan); Salam Chair in Physics, GC University, Lahore-54000 (Pakistan); Jamil, M.; Shah, H. A. [Department of Physics, GC University, Lahore-54000 (Pakistan); Murtaza, G. [Salam Chair in Physics, GC University, Lahore-54000 (Pakistan)
2009-01-15T23:59:59.000Z
Jeans instability in a homogeneous cold quantum dusty plasma in the presence of the ambient magnetic field and the quantum effect arising through the Bohm potential has been examined using the quantum magnetohydrodynamic model. It is found that the Jeans instability is significantly reduced by the presence of the dust-lower-hybrid wave and the ion quantum effect. The minimum wavenumber for Jeans stability depends clearly on ion quantum effect and the dust-lower-hybrid frequency also.
High-frequency Probing Diagnostic for Hall Current Plasma Thrusters
A.A. Litvak; Y. Raitses; N.J. Fisch
2001-10-25T23:59:59.000Z
High-frequency oscillations (1-100 MHz) in Hall thrusters have apparently eluded significant experimental scrutiny. A diagnostic setup, consisting of a single Langmuir probe, a special shielded probe connector-positioner, and an electronic impedance-matching circuit, was successfully built and calibrated. Through simultaneous high-frequency probing of the Hall thruster plasma at multiple locations, high-frequency plasma waves have been identified and characterized for various thruster operating conditions.
Wetzel, Christian M.
IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 55, NO. 6, DECEMBER 2008 3633 Radiation Effects on In to 500 keV alpha particles to fluences above 1014 cm2 to probe the relative radiation tolerance that the quantum well luminescence decay rate is dom- inated by radiation-induced defects in the GaN epilayer. In
S. Denisov; S. Kohler; P. Hanggi
2009-02-24T23:59:59.000Z
We investigate the quantum ratchet effect under the influence of weak dissipation which we treat within a Floquet-Markov master equation approach. A ratchet current emerges when all relevant symmetries are violated. Using time-reversal symmetric driving we predict a purely dissipation-induced quantum ratchet current. This directed quantum transport results from bath-induced superpositions of non-transporting Floquet states.
Observation of chiral edge states with neutral fermions in synthetic Hall ribbons
Mancini, M; Cappellini, G; Livi, L; Rider, M; Catani, J; Sias, C; Zoller, P; Inguscio, M; Dalmonte, M; Fallani, L
2015-01-01T23:59:59.000Z
Chiral edge states are a hallmark of quantum Hall physics. In electronic systems, they appear as a macroscopic consequence of the cyclotron orbits induced by a magnetic field, which are naturally truncated at the physical boundary of the sample. Here we report on the experimental realization of chiral edge states in a ribbon geometry with an ultracold gas of neutral fermions subjected to an artificial gauge field. By imaging individual sites along a synthetic dimension, we detect the existence of the edge states, investigate the onset of chirality as a function of the bulk-edge coupling, and observe the edge-cyclotron orbits induced during a quench dynamics. The realization of fermionic chiral edge states is a fundamental achievement, which opens the door towards experiments including edge state interferometry and the study of non-Abelian anyons in atomic systems.
Observation of chiral edge states with neutral fermions in synthetic Hall ribbons
M. Mancini; G. Pagano; G. Cappellini; L. Livi; M. Rider; J. Catani; C. Sias; P. Zoller; M. Inguscio; M. Dalmonte; L. Fallani
2015-02-09T23:59:59.000Z
Chiral edge states are a hallmark of quantum Hall physics. In electronic systems, they appear as a macroscopic consequence of the cyclotron orbits induced by a magnetic field, which are naturally truncated at the physical boundary of the sample. Here we report on the experimental realization of chiral edge states in a ribbon geometry with an ultracold gas of neutral fermions subjected to an artificial gauge field. By imaging individual sites along a synthetic dimension, we detect the existence of the edge states, investigate the onset of chirality as a function of the bulk-edge coupling, and observe the edge-cyclotron orbits induced during a quench dynamics. The realization of fermionic chiral edge states is a fundamental achievement, which opens the door towards experiments including edge state interferometry and the study of non-Abelian anyons in atomic systems.
Quantum Black Holes Effects on the Shape of Extensive Air Showers
Nicusor Arsene; Lauretiu Ioan Caramete; Peter B. Denton; Octavian Micu
2014-07-08T23:59:59.000Z
We investigate the possibility to find a characteristic TeV scale quantum black holes decay signature in the data recorded by cosmic rays experiments. TeV black holes can be produced via the collisions of ultra high energetic protons (E > $10^18$ eV) with nucleons the from atmosphere. We focus on the case when the black holes decay into two particles moving in the forward direction in the Earth reference frame (back-to-back in the center of mass reference frame) and induce two overlapping showers. When reconstructing both the energy and the shape of the resultant air shower, there is a significant difference between showers induced only via standard model interactions and showers produced via the back-to-back decay of black holes as intermediate states.
Effect of polarization on intersubband transition in AlGaN/GaN multiple quantum wells
Chen, G.; Li, Z. L.; Wang, X. Q.; Huang, C. C.; Rong, X.; Xu, F. J.; Tang, N.; Qin, Z. X.; Shen, B. [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China)] [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Sang, L. W.; Sumiya, M. [Optical and Electronic Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)] [Optical and Electronic Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Chen, Y. H. [Laboratory of Semiconductor Material Science, Institute of Semiconductors, CAS, Beijing 100083 (China)] [Laboratory of Semiconductor Material Science, Institute of Semiconductors, CAS, Beijing 100083 (China); Ge, W. K. [Department of Physics, Tsinghua University, Beijing 100871 (China)] [Department of Physics, Tsinghua University, Beijing 100871 (China)
2013-05-13T23:59:59.000Z
Intersubband transitions (ISBT) of AlGaN/GaN multiple quantum wells (MQWs) with wavelength towards atmospheric window (3-5 {mu}m) have been investigated. A Ga-excess epitaxial method is used in the molecular beam epitaxy leading to ultra-sharp interface and negligible elements inter-diffusion. The absorption peak wavelength of the ISBT was successfully tuned in the range of 3-4 {mu}m by modifying the GaN well thickness from 2.8 to 5.5 nm. It was further found that the polarization charge density of the AlGaN/GaN MQWs was about -0.034 C/m{sup 2} which gave rise to blueshift of the ISBT wavelength and thus partially compensated its redshift with increasing well thickness.
R. Y. Chiao; S. J. Minter; K. Wegter-McNelly; L. A. Martinez
2010-11-02T23:59:59.000Z
Freely falling point-like objects converge toward the center of the Earth. Hence the gravitational field of the Earth is inhomogeneous, and possesses a tidal component. The free fall of an extended quantum mechanical object such as a hydrogen atom prepared in a high principal-quantum-number state, i.e. a circular Rydberg atom, is predicted to fall more slowly than a classical point-like object, when both objects are dropped from the same height above the Earth's surface. This indicates that, apart from transitions between quantum states, the atom exhibits a kind of quantum mechanical incompressibility during free fall in inhomogeneous, tidal gravitational fields like those of the Earth. A superconducting ring-like system with a persistent current circulating around it behaves like the circular Rydberg atom during free fall. Like the electronic wavefunction of the freely falling atom, the Cooper-pair wavefunction is quantum mechanically incompressible. The ions in the lattice of the superconductor, however, are not incompressible, since they do not possess a globally coherent quantum phase. The resulting difference during free fall in the response of the nonlocalizable Cooper pairs of electrons and the localizable ions to inhomogeneous gravitational fields is predicted to lead to a charge separation effect, which in turn leads to a large Coulomb force that opposes the convergence caused by the tidal gravitational force on the superconducting system. A "Cavendish-like" experiment is proposed for observing the charge separation effect induced by inhomogeneous gravitational fields in a superconducting circuit. The charge separation effect is determined to be limited by a pair-breaking process that occurs when low frequency gravitational perturbations are present.
Alfredo Iorio; Gaetano Lambiase
2014-12-15T23:59:59.000Z
The solutions of many issues, of the ongoing efforts to make deformed graphene a tabletop quantum field theory in curved spacetimes, are presented. A detailed explanation of the special features of curved spacetimes, originating from embedding portions of the Lobachevsky plane into $\\mathbf{R}^3$, is given, and the special role of coordinates for the physical realizations in graphene, is explicitly shown, in general, and for various examples. The Rindler spacetime is reobtained, with new important differences with respect to earlier results. The de Sitter spacetime naturally emerges, for the first time, paving the way to future applications in cosmology. The role of the BTZ black hole is also briefly addressed. The singular boundary of the pseudospheres, "Hilbert horizon", is seen to be closely related to event horizon of the Rindler, de Sitter, and BTZ kind. This gives new, and stronger, arguments for the Hawking phenomenon to take place. An important geometric parameter, $c$, overlooked in earlier work, takes here its place for physical applications, and it is shown to be related to graphene's lattice spacing, $\\ell$. It is shown that all surfaces of constant negative curvature, ${\\cal K} = -r^{-2}$, are unified, in the limit $c/r \\to 0$, where they are locally applicable to the Beltrami pseudosphere. This, and $c = \\ell$, allow us a) to have a phenomenological control on the reaching of the horizon; b) to use spacetimes different than Rindler for the Hawking phenomenon; c) to approach the generic surface of the family. An improved expression for the thermal LDOS is obtained. A non-thermal term for the total LDOS is found. It takes into account: a) the peculiarities of the graphene-based Rindler spacetime; b) the finiteness of a laboratory surface; c) the optimal use of the Minkowski quantum vacuum, through the choice of this Minkowski-static boundary.
Weng, Q. C. [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241 (China); An, Z. H., E-mail: anzhenghua@fudan.edu.cn, E-mail: luwei@mail.sitp.ac.cn [State Key Laboratory of Surface Physics and Institute of Advanced Materials, Fudan University, Shanghai 200433 (China); Xiong, D. Y.; Zhu, Z. Q. [Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241 (China); Zhang, B.; Chen, P. P.; Li, T. X.; Lu, W., E-mail: anzhenghua@fudan.edu.cn, E-mail: luwei@mail.sitp.ac.cn [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China)
2014-07-21T23:59:59.000Z
We present the photocurrent spectrum study of a quantum dot (QD) single-photon detector using a reset technique which eliminates the QD's “memory effect.” By applying a proper reset frequency and keeping the detector in linear-response region, the detector's responses to different monochromatic light are resolved which reflects different detection efficiencies. We find the reset photocurrent tails up to 1.3??m wavelength and near-infrared (?1100?nm) single-photon sensitivity is demonstrated due to interband transition of electrons in QDs, indicating the device a promising candidate both in quantum information applications and highly sensitive imaging applications operating in relative high temperatures (>80?K).
Systematic relativistic quantum effects on screening of fusion rates in white dwarfs
Shirish M. Chitanvis
2006-11-21T23:59:59.000Z
Relativistic electron degeneracy effects are dominant in ultra-dense plasmas (UDP), such as those found in white dwarfs. These effects can be treated systematically by obtaining an expansion of the screening length in inverse powers of $\\hbar^{2}$. In general, our theory leads to an ${\\cal O}(10)$ effect on the enhancement of fusion rates in white dwarfs. Further, it is shown analytically for these stellar conditions that Bose statistics of nuclei have a negligible effect on the screening length, in consonance with Monte Carlo simulations found in literature.
Systematic quantum effects on screening of fusion rates in white dwarfs
Shirish M. Chitanvis
2006-10-19T23:59:59.000Z
Electron degeneracy effects are dominant in ultra-dense plasmas (UDP), such as those found in white dwarfs. These effects can be treated systematically by obtaining an expansion of the screening length in inverse powers of $\\hbar^{2}$. The theory exhibits Thomas-Fermi-like screening in an appropriate regime. In general, our theory leads to an ${\\cal O}(1)$ effect on the enhancement of fusion rates in white dwarfs. Further, it is shown analytically for these stellar conditions that Bose statistics of nuclei have a negligible effect on the screening length, in consonance with Monte Carlo simulations found in literature.
Vinson, N.; Freitag, H.; Micha, D. A., E-mail: micha@qtp.ufl.edu [Quantum Theory Project, Departments of Chemistry and Physics, University of Florida, Gainesville, Florida 32611 (United States)
2014-06-28T23:59:59.000Z
Starting from the atomic structure of silicon quantum dots (QDs), and utilizing ab initio electronic structure calculations within the Förster resonance energy transfer (FRET) treatment, a model has been developed to characterize electronic excitation energy transfer between QDs. Electronic energy transfer rates, K{sub EET}, between selected identical pairs of crystalline silicon quantum dots systems, either bare, doped with Al or P, or adsorbed with Ag and Ag{sub 3}, have been calculated and analyzed to extend previous work on light absorption by QDs. The effects of their size and relative orientation on energy transfer rates for each system have also been considered. Using time-dependent density functional theory and the hybrid functional HSE06, the FRET treatment was employed to model electronic energy transfer rates within the dipole-dipole interaction approximation. Calculations with adsorbed Ag show that: (a) addition of Ag increases rates up to 100 times, (b) addition of Ag{sub 3} increases rates up to 1000 times, (c) collinear alignment of permanent dipoles increases transfer rates by an order of magnitude compared to parallel orientation, and (d) smaller QD-size increases transfer due to greater electronic orbitals overlap. Calculations with dopants show that: (a) p-type and n-type dopants enhance energy transfer up to two orders of magnitude, (b) surface-doping with P and center-doping with Al show the greatest rates, and (c) K{sub EET} is largest for collinear permanent dipoles when the dopant is on the outer surface and for parallel permanent dipoles when the dopant is inside the QD.
Evgeny G. Fateev
2013-01-20T23:59:59.000Z
In a popular language, the possibilities of the Casimir expulsion effect are presented, which can be the basis of quantum motors. Such motors can be in the form of a special multilayer thin film with periodic and complex nanosized structures. Quantum motors of the type of the Casimir platforms can be the base of transportation, energy and many other systems in the future.
Magnetic shielding of Hall thrusters at high discharge voltages
Mikellides, Ioannis G., E-mail: Ioannis.G.Mikellides@jpl.nasa.gov; Hofer, Richard R.; Katz, Ira; Goebel, Dan M. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States)
2014-08-07T23:59:59.000Z
A series of numerical simulations and experiments have been performed to assess the effectiveness of magnetic shielding in a Hall thruster operating in the discharge voltage range of 300–700?V (I{sub sp}???2000–2700?s) at 6?kW, and 800?V (I{sub sp} ? 3000) at 9?kW. At 6?kW, the magnetic field topology with which highly effective magnetic shielding was previously demonstrated at 300?V has been retained for all other discharge voltages; only the magnitude of the field has been changed to achieve optimum thruster performance. It is found that magnetic shielding remains highly effective for all discharge voltages studied. This is because the channel is long enough to allow hot electrons near the channel exit to cool significantly upon reaching the anode. Thus, despite the rise of the maximum electron temperature in the channel with discharge voltage, the electrons along the grazing lines of force remain cold enough to eliminate or reduce significantly parallel gradients of the plasma potential near the walls. Computed maximum erosion rates in the range of 300–700?V are found not to exceed 10{sup ?2}?mm/kh. Such rates are ?3 orders of magnitude less than those observed in the unshielded version of the same thruster at 300?V. At 9?kW and 800?V, saturation of the magnetic circuit did not allow for precisely the same magnetic shielding topology as that employed during the 6-kW operation since this thruster was not designed to operate at this condition. Consequently, the maximum erosion rate at the inner wall is found to be ?1 order of magnitude higher (?10{sup ?1}?mm/kh) than that at 6?kW. At the outer wall, the ion energy is found to be below the sputtering yield threshold so no measurable erosion is expected.
Tao, X. D.; Feng, Z.; Miao, B. F.; Sun, L.; You, B.; Wu, D.; Du, J.; Zhang, W.; Ding, H. F., E-mail: hfding@nju.edu.cn [Department of Physics, National Laboratory of Solid State Microstructures, Nanjing University, 22 Hankou Road, Nanjing 210093 (China)
2014-05-07T23:59:59.000Z
We present the experimental study of the spin Hall angle (SHA) and spin diffusion length of Pd with the spin pumping and microwave photoresistance effects. The Py/Pd bilayer stripes are excited with an out-of-plane microwave magnetic field. The pure spin current is thus pumped and transforms into charge current via the inverse spin Hall effect (ISHE) in Pd layer, yielding an ISHE voltage. The ISHE voltage can be distinguished from the unwanted signal caused by the anisotropic magnetoresistance according to their different symmetries. Together with Pd thickness dependent measurements of in and out-of-plane precessing angles and effective spin mixing conductance, the SHA and spin-diffusion length of Pd are quantified as 0.0056?±?0.0007 and 7.3?±?0.7?nm, respectively.
TRINITY HALL TRINITY LANE CAMBRIDGE CB2 1TJ conference@trinhall.cam.ac.uk 01223 764444
Lasenby, Joan
TRINITY HALL TRINITY LANE CAMBRIDGE CB2 1TJ conference@trinhall.cam.ac.uk 01223 764444 TRINITY HALL, minerally too with subtle nutty oak on a long finish. 1 #12;TRINITY HALL TRINITY LANE CAMBRIDGE CB2 1TJ
Jeremy L. O'Brien; Akira Furusawa; Jelena Vu?kovi?
2010-03-20T23:59:59.000Z
The first quantum technology, which harnesses uniquely quantum mechanical effects for its core operation, has arrived in the form of commercially available quantum key distribution systems that achieve enhanced security by encoding information in photons such that information gained by an eavesdropper can be detected. Anticipated future quantum technologies include large-scale secure networks, enhanced measurement and lithography, and quantum information processors, promising exponentially greater computation power for particular tasks. Photonics is destined for a central role in such technologies owing to the need for high-speed transmission and the outstanding low-noise properties of photons. These technologies may use single photons or quantum states of bright laser beams, or both, and will undoubtably apply and drive state-of-the-art developments in photonics.
Multi-photon quantum communication in quantum networks
Wei Qin; Chuan Wang; Ye Cao; Gui Lu Long
2015-03-17T23:59:59.000Z
We propose and analyze a multiphoton-state coherent transport protocol in a coupled-resonator quantum network. A multiphoton swap gate between two antipodes can be achieved with neither external modulation nor coupling strength engineering. Moreover, we extend this result to a coupled-resonator chain of arbitrary length with different coupling strengths. Effects of decoherence via quantum nondemolition interaction are studied with sources including vacuum quantum fluctuation and bath thermal excitations when the bath is in the thermal equilibrium state. These observations are helpful to understand the decoherence effects on quantum communication in quantum coupled-resonator systems.
Tunnel determinants from spectral zeta functions. Instanton effects in quantum mechanics
Izquierdo, A. Alonso [Departamento de Matematica Aplicada and IUFFyM, Universidad de Salamanca (Spain); Guilarte, J. Mateos [Departamento de Fisica Fundamental and IUFFyM, Universidad de Salamanca (Spain)
2014-07-23T23:59:59.000Z
In this paper we develop an spectral zeta function regularization procedure on the determinants of instanton fluctuation operators that describe the semi-classical order of tunnel effects between degenerate vacua.
Quantum optics and cavity QED with quantum dots in photonic crystals
Jelena Vuckovic
2014-02-11T23:59:59.000Z
This chapter will primarily focus on the studies of quantum optics with semiconductor, epitaxially grown quantum dots embedded in photonic crystal cavities. We will start by giving brief introductions into photonic crystals and quantum dots, then proceed with the introduction to cavity quantum electrodynamics (QED) effects, with a particular emphasis on the demonstration of these effects on the quantum dot-photonic crystal platform. Finally, we will focus on the applications of such cavity QED effects.
Quantum teleportation between moving detectors
Shih-Yuin Lin; Chung-Hsien Chou; B. L. Hu
2015-05-10T23:59:59.000Z
It is commonly believed that the fidelity of quantum teleportation using localized quantum objects with one party or both accelerated in vacuum would be degraded due to the heat-up by the Unruh effect. In this paper we point out that the Unruh effect is not the whole story in accounting for all the relativistic effects in quantum teleportation. First, there could be degradation of fidelity by a common field environment even when both quantum objects are in inertial motion. Second, relativistic effects entering the description of the dynamics such as frame dependence, time dilation, and Doppler shift, already existent in inertial motion, can compete with or even overwhelm the effect due to uniform acceleration in a quantum field. We show it is not true that larger acceleration of an object would necessarily lead to a faster degradation of fidelity. These claims are based on four cases of quantum teleportation we studied using two Unruh-DeWitt detectors coupled via a common quantum field initially in the Minkowski vacuum. We find the quantum entanglement evaluated around the light cone, rather than the conventional ones evaluated on the Minkowski time-slices, is the necessary condition for the averaged fidelity of quantum teleportation beating the classical one. These results are useful as a guide to making judicious choices of states and parameter ranges and estimation of the efficiency of quantum teleportation in relativistic quantum systems under environmental influences.
Strong reactions in quantum super PDEs. III: Exotic quantum supergravity
Agostino Prástaro
2015-03-10T23:59:59.000Z
Following the previous two parts, of a work devoted to encode strong reaction dynamics in the A. Pr\\'astaro's algebraic topology of quantum super PDE's, nonlinear quantum propagators in the observed quantum super Yang-Mills PDE, $\\hat{(YM)}[i]$, are further characterized. In particular, nonlinear quantum propagators with non-zero defect quantum electric-charge, are interpreted as {\\em exotic-quantum supergravity} effects. As an application, the recently discovered bound-state called $Zc(3900)$, is obtained as a neutral quasi-particle, generated in a $Q$-quantum exotic supergravity process. {\\em Quantum entanglement} is justified by means of the algebraic topologic structure of nonlinear quantum propagators. Quantum Cheshire cats are considered as examples of quantum entanglements. Existence theorem for solutions of $\\hat{(YM)}[i]$ admitting negative local temperatures ({\\em quantum thermodynamic-exotic solutions}) is obtained too and related to quantum entanglement. Such exotic solutions are used to encode Universe at the Planck-epoch. It is proved that the Universe's expansion at the Planck epoch is justified by the fact that it is encoded by a nonlinear quantum propagator having thermodynamic quantum exotic components in its boundary. This effect produces also an increasing of energy in the Universe at the Einstein epoch: {\\em Planck-epoch-legacy} on the boundary of our Universe. This is the main source of the Universe's expansion and solves the problem of the non-apparent energy-matter ({\\em dark-energy-matter}) in the actual Universe. Breit-Wheeler-type processes have been proved in the framework of the Pr\\'astaro's algebraic topology of quantum super Yang-Mills PDEs. Numerical comparisons of nonlinear quantum propagators with Weinberg-Salam electroweak theory in Standard Model are given.
Strong reactions in quantum super PDEs. III: Exotic quantum supergravity
Agostino Prástaro
2015-03-23T23:59:59.000Z
Following the previous two parts, of a work devoted to encode strong reaction dynamics in the A. Pr\\'astaro's algebraic topology of quantum super PDE's, nonlinear quantum propagators in the observed quantum super Yang-Mills PDE, $\\hat{(YM)}[i]$, are further characterized. In particular, nonlinear quantum propagators with non-zero defect quantum electric-charge, are interpreted as {\\em exotic-quantum supergravity} effects. As an application, the recently discovered bound-state called $Zc(3900)$, is obtained as a neutral quasi-particle, generated in a $Q$-quantum exotic supergravity process. {\\em Quantum entanglement} is justified by means of the algebraic topologic structure of nonlinear quantum propagators. Quantum Cheshire cats are considered as examples of quantum entanglements. Existence theorem for solutions of $\\hat{(YM)}[i]$ admitting negative local temperatures ({\\em quantum thermodynamic-exotic solutions}) is obtained too and related to quantum entanglement. Such exotic solutions are used to encode Universe at the Planck-epoch. It is proved that the Universe's expansion at the Planck epoch is justified by the fact that it is encoded by a nonlinear quantum propagator having thermodynamic quantum exotic components in its boundary. This effect produces also an increasing of energy in the Universe at the Einstein epoch: {\\em Planck-epoch-legacy} on the boundary of our Universe. This is the main source of the Universe's expansion and solves the problem of the non-apparent energy-matter ({\\em dark-energy-matter}) in the actual Universe. Breit-Wheeler-type processes have been proved in the framework of the Pr\\'astaro's algebraic topology of quantum super Yang-Mills PDEs. Numerical comparisons of nonlinear quantum propagators with Weinberg-Salam electroweak theory in Standard Model are given.
Strong reactions in quantum super PDEs. III: Exotic quantum supergravity
Agostino Prástaro
2015-02-01T23:59:59.000Z
Following the previous two parts, of a work devoted to encode strong reaction dynamics in the A. Pr\\'astaro's algebraic topology of quantum super PDE's, nonlinear quantum propagators in the observed quantum super Yang-Mills PDE, $\\hat{(YM)}[i]$, are further characterized. In particular, nonlinear quantum propagators with non-zero defect quantum electric-charge, are interpreted as {\\em exotic-quantum supergravity} effects. As an application, the recently discovered bound-state called $Zc(3900)$, is obtained as a neutral quasi-particle, generated in a $Q$-quantum exotic supergravity process. {\\em Quantum entanglement} is justified by means of the algebraic topologic structure of nonlinear quantum propagators. Quantum Cheshire cats are considered as examples of quantum entanglements. Existence theorem for solutions of $\\hat{(YM)}[i]$ admitting negative local temperatures ({\\em quantum thermodynamic-exotic solutions}) is obtained too and related to quantum entanglement. Such exotic solutions are used to encode Universe at the Planck-epoch. It is proved that the Universe's expansion at the Planck epoch is justified by the fact that it is encoded by a nonlinear quantum propagator having thermodynamic quantum exotic components in its boundary. This effect produces also an increasing of energy in the Universe at the Einstein epoch: {\\em Planck-epoch-legacy} on the boundary of our Universe. This is the main source of the Universe's expansion and solves the problem of the non-apparent energy-matter ({\\em dark-energy-matter}) in the actual Universe. Breit-Wheeler-type processes have been proved in the framework of the Pr\\'astaro's algebraic topology of quantum super Yang-Mills PDEs. Numerical comparisons of nonlinear quantum propagators with Weinberg-Salam electroweak theory in Standard Model are given.
Characterizing low-frequency oscillation of Hall thrusters by dielectric wall temperature variation
Ning, Guo [Science and Technology on Vacuum and Cryogenics Technology and Physics Laboratory, Lanzhou 730013 (China); Liqiu, Wei, E-mail: weiliqiu@gmail.com, E-mail: weiliqiu@hit.edu.cn; Yongjie, Ding [Harbin Institute of Technology, Mail Box 3047, Harbin 150001 (China)
2014-05-15T23:59:59.000Z
The low-frequency oscillation characteristics of a Hall thruster were investigated by varying the dielectric wall temperature. Experimental results indicate that increasing the dielectric wall temperature can result in an increase in the amplitude of low-frequency oscillation and a slight decrease in its frequency. Physical analysis revealed that this change is related to the secondary electron emissions at different dielectric wall temperatures. The evidence suggests that this technique can serve as an effective way for future studies to examine how secondary electron emissions affect a discharging thruster.
Fundamental Difference between the Two Variants of Hall Thrusters: SPT and TAL
Choueiri, Edgar
, 3]. At this early date in its history, the device was simply called a Hall current ion accel- erator magnetic field and typical particle trajectories. a substantial resurge in interest[12] in Hall thrusters
Lucien Hardy
2013-03-06T23:59:59.000Z
We discuss how to reconstruct quantum theory from operational postulates. In particular, the following postulates are consistent only with for classical probability theory and quantum theory. Logical Sharpness: There is a one-to-one map between pure states and maximal effects such that we get unit probability. This maximal effect does not give probability equal to one for any other pure state. Information Locality: A maximal measurement is effected on a composite system if we perform maximal measurements on each of the components. Tomographic Locality: The state of a composite system can be determined from the statistics collected by making measurements on the components. Permutability: There exists a reversible transformation on any system effecting any given permutation of any given maximal set of distinguishable states for that system. Sturdiness: Filters are non-flattening. To single out quantum theory we need only add any requirement that is inconsistent with classical probability theory and consistent with quantum theory.
Martin Bojowald
2012-12-20T23:59:59.000Z
Inhomogeneous space-times in loop quantum cosmology have come under better control with recent advances in effective methods. Even highly inhomogeneous situations, for which multiverse scenarios provide extreme examples, can now be considered at least qualitatively.
Bojowald, Martin
2013-01-01T23:59:59.000Z
Inhomogeneous space-times in loop quantum cosmology have come under better control with recent advances in effective methods. Even highly inhomogeneous situations, for which multiverse scenarios provide extreme examples, can now be considered at least qualitatively.
Reconnection events in two-dimensional Hall magnetohydrodynamic turbulence
Donato, S.; Servidio, S.; Carbone, V. [Dipartimento di Fisica, Universita della Calabria, I-87036 Cosenza (Italy); Dmitruk, P. [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Fisica de Buenos Aires, CONICET, Buenos Aires (Argentina); Shay, M. A.; Matthaeus, W. H. [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Cassak, P. A. [Department of Physics, West Virginia University, Morgantown, West Virginia 26506 (United States)
2012-09-15T23:59:59.000Z
The statistical study of magnetic reconnection events in two-dimensional turbulence has been performed by comparing numerical simulations of magnetohydrodynamics (MHD) and Hall magnetohydrodynamics (HMHD). The analysis reveals that the Hall term plays an important role in turbulence, in which magnetic islands simultaneously reconnect in a complex way. In particular, an increase of the Hall parameter, the ratio of ion skin depth to system size, broadens the distribution of reconnection rates relative to the MHD case. Moreover, in HMHD the local geometry of the reconnection region changes, manifesting bifurcated current sheets and quadrupolar magnetic field structures in analogy to laminar studies, leading locally to faster reconnection processes in this case of reconnection embedded in turbulence. This study supports the idea that the global rate of energy dissipation is controlled by the large scale turbulence, but suggests that the distribution of the reconnection rates within the turbulent system is sensitive to the microphysics at the reconnection sites.
D0 Detector Collision Hall Oxygen Deficiancy Hazard Analysis
Wu, J.; /Fermilab
1992-08-06T23:59:59.000Z
EN-258, D0 Platform ODH Analysts. provided the oxygen deficiency hazard analysts for the D0 detector in the Assembly Hall. This note covers the same analysis. but revised for the Collision Hall. Liquid cryogens. released and warming to atmosphere conditions, expand to, on average, seven hundred times their liquid volume, and displace vital atmospheric oxygen. An oxygen deficiency hazard analysis assesses the increased risk to personnel in areas containing cryogenic systems. The D0 detector Collision Hall ODH analysis has been approached five different ways using established methods. If the low beta quad magnets are powered, and the exhaust rate is below 4220 scfm, the area is ODH class 1. In any other case, the analysis shows the area to be ODH class 0 as equipped (with ventilation fans) and requiring no special safety provisions. System designers have provided for a reduced oxygen level detection and warning system as well as emergency procedures to address fault conditions.
Novel Hall sensors developed for magnetic field imaging systems.
Cambel, V.; Karapetrov, G.; Novosad, V.; Bartolome, E.; Gregusova, D.; Fedor, J.; Kudela, R.; Soltys, J.; Materials Science Division; Slovak Academy of Sciences; Univ. Autonoma de Barcelona
2007-09-01T23:59:59.000Z
We report here on the fabrication and application of novel planar Hall sensors based on shallow InGaP/AlGaAs/GaAs heterostructure with a two-dimensional electron gas (2DEG) as an active layer. The sensors are developed for two kinds of experiments. In the first one, magnetic samples are placed directly on the Hall sensor. Room temperature experiments of permalloy objects evaporated onto the sensor are presented. In the second experiment, the sensor scans close over a multigranular superconducting sample prepared on a YBCO thin film. Large-area and high-resolution scanning experiments were performed at 4.2 K with the Hall probe scanning system in a liquid helium flow cryostat.
Arka Majumdar; Erik D. Kim; Jelena Vuckovic
2011-07-24T23:59:59.000Z
We experimentally observe the effect of photo-generated carriers on the spectral diffusion of a quantum dot (QD) coupled to a photonic crystal (PC) cavity. In this system, spectral diffusion arises in part from charge fluctuations on the etched surfaces of the PC. We find that these fluctuations may be suppressed by photo-generated carriers, leading to a reduction of the measured QD linewidth by a factor of ~2 compared to the case where the photo-generated carriers are not present. This result demonstrates a possible means of countering the effects of spectral diffusion in QD-PC cavity systems and thus may be useful for quantum information applications where narrow QD linewidths are desired.
Gherib, Rami; Izmaylov, Artur F
2015-01-01T23:59:59.000Z
Adequate simulation of non-adiabatic dynamics through conical intersection requires account for a non-trivial geometric phase (GP) emerging in electronic and nuclear wave-functions in the adiabatic representation. Popular mixed quantum-classical (MQC) methods, surface hopping and Ehrenfest, do not carry a nuclear wave-function to be able to incorporate the GP into nuclear dynamics. Surprisingly, the MQC methods reproduce ultra-fast interstate crossing dynamics generated with the exact quantum propagation so well as if they contained information about the GP. Using two-dimensional linear vibronic coupling models we unravel how the MQC methods can effectively mimic the most significant dynamical GP effects: 1) compensation for repulsive diagonal second order non-adiabatic couplings and 2) transfer enhancement for a fully cylindrically symmetric component of a nuclear distribution.
Chauveau, J.-M.; Vinter, B. [Centre de Recherche sur l'Hetero-Epitaxie et ses Applications, Centre National de la Recherche Scientifique (CRHEA-CNRS), Rue B. Gregory, F-06560 Valbonne Sophia Antipolis (France); University of Nice Sophia Antipolis, Parc Valrose, F-06102 Nice Cedex 2 (France); Teisseire, M.; Morhain, C.; Deparis, C. [Centre de Recherche sur l'Hetero-Epitaxie et ses Applications, Centre National de la Recherche Scientifique (CRHEA-CNRS), Rue B. Gregory, F-06560 Valbonne Sophia Antipolis (France); Kim-Chauveau, H.
2011-05-15T23:59:59.000Z
We report on the properties of nonpolar a-plane (Zn,Mg)O/ZnO quantum wells (QW) grown by molecular beam epitaxy on r plane sapphire and a plane ZnO substrates. For the QWs grown on sapphire, the anisotropy of the lattice parameters of the (Zn,Mg)O barrier gives rise to an unusual in-plane strain state in the ZnO QWs, which induces a strong blue-shift of the excitonic transitions, in addition to the confinement effects. We observe this blue-shift in photoluminescence excitation experiments. The photoluminescence excitation energies of the QWs are satisfactorily simulated when taking into account the variation of the exciton binding energy with the QW width and the residual anisotropic strain. Then we compare the photoluminescence properties of homoepitaxial QWs grown on ZnO bulk substrate and heteroepitaxial QWs grown on sapphire. We show that the reduction of structural defects and the improvement of surface morphology are correlated with a strong enhancement of the photoluminescence properties: reduction of full width at half maximum, strong increase of the luminescence intensities. The comparison convincingly demonstrates the interest of homoepitaxial nonpolar QWs for bright UV emission applications.
Beyond the scalar Higgs, in lattice quantum field theory
Schroeder, Christopher Robert
2009-01-01T23:59:59.000Z
as an effective field theory . . . . . Higgs mass upperHiggs, in Lattice Quantum Field Theory by Christopher Robertin Lattice Quantum Field Theory A dissertation submitted in
An edition of Hall Caine's The Demon Lover
Linnstaedter, Joan
1993-01-01T23:59:59.000Z
became the seat of the baronet of his line. He was made a Knight of Her Royal Court in 1918. Hall Caine was a very popular novelist during his own lifetime? popular enough to make his living by writing ? but shortly after his death (31 August 1931... beneath the names of the plays, also in all caps. Short gold lines of approximately half an inch are centered between each of the titles as they are listed. In the very center of the cover Hall Caine appears in the same size caps as the titles...
HIGH ACCURACY BEAM CURRENT MONITOR SYSTEM FOR CEBAF'S EXPERIMENTAL HALL A *
HIGH ACCURACY BEAM CURRENT MONITOR SYSTEM FOR CEBAF'S EXPERIMENTAL HALL A * J.-C. Denard , A. Saha CEBAF accelerator delivers continuous wave (CW) electron beams to three experimental Halls. In Hall A is described. 1 INTRODUCTION The CEBAF accelerator delivers continuous wave (CW) electron beams to three
PUBLICATIONS OF CHARLES A.S. HALL {Chronological} as of October 2012. Books are in bold.
Hall, Charles A.S.
-21. 12. Hall, C.A.S. 1975. Models and the decision-making process: The Hudson River power plant case Productivity of the Biosphere. Springer-Verlag, New York. 15. (Review) Hall, C.A.S. 1975. Electric Power Plants.A. and C.A.S. Hall. 1972. Systems Analysis and Simulation in Ecology, Vol. 1 edited by B.C. Patten
Take a seat... Development Office, Trinity Hall, Cambridge, CB2 1TJ
Lasenby, Joan
Take a seat... Take a seat... Development Office, Trinity Hall, Cambridge, CB2 1TJ www.trinhall.cam.ac.uk fundraising@trinhall.cam.ac.uk Tel: 01223 766345 Fax: 01223 765157 Trinity Hall Cambridge registered charity the chair. GIFT AID DECLARATION I would like Trinity Hall, Cambridge to treat all donations that I have made
AC transport in p-Ge/GeSi quantum well in high magnetic fields
Drichko, I. L.; Malysh, V. A.; Smirnov, I. Yu.; Golub, L. E.; Tarasenko, S. A. [A.F. Ioffe Physical Technical Institute of Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Suslov, A. V. [National High Magnetic Field Laboratory, Tallahassee, FL 32310 (United States); Mironov, O. A. [Warwick SEMINANO R and D Center, University of Warwick Science Park, Coventry CV4 7EZ (United Kingdom); Kummer, M.; Känel, H. von [Laboratorium für Festkörperphysik ETH Zürich, CH-8093 Zürich (Switzerland)
2014-08-20T23:59:59.000Z
The contactless surface acoustic wave technique is implemented to probe the high-frequency conductivity of a high-mobility p-Ge/GeSi quantum well structure in the regime of integer quantum Hall effect (IQHE) at temperatures 0.3–5.8 K and magnetic fields up to 18 T. It is shown that, in the IQHE regime at the minima of conductivity, holes are localized and ac conductivity is of hopping nature and can be described within the “two-site” model. The analysis of the temperature and magnetic-field-orientation dependence of the ac conductivity at odd filing factors enables us to determine the effective hole g-factor, |g{sub zz}|?4.5. It is shown that the in-plane component of the magnetic field leads to a decrease in the g-factor as well as increase in the cyclotron mass, which is explained by orbital effects in the complex valence band of germanium.