Microscopic theory of quantum anomalous Hall effect in graphene...
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Microscopic theory of quantum anomalous Hall effect in graphene Prev Next Title: Microscopic theory of quantum anomalous Hall effect in graphene Authors: Qiao, Zhenhua ;...
Unconventional Integer Quantum Hall effect in graphene
V. P. Gusynin; S. G. Sharapov
2005-08-16
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
2012-04-24
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 $\
Fractional quantum Hall effect and nonabelian statistics
N. Read; G. Moore
1992-02-03
It is argued that fractional quantum Hall effect wavefunctions can be interpreted as conformal blocks of two-dimensional conformal field theory. Fractional statistics can be extended to nonabelian statistics and examples can be constructed from conformal field theory. The Pfaffian state is related to the 2D Ising model and possesses fractionally charged excitations which are predicted to obey nonabelian statistics.
Integer Quantum Hall Effect in Graphene
Jellal, Ahmed
2015-01-01
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
2015-04-24
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.
Robert B. Laughlin and the Fractional Quantum Hall Effect
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Fractional Quantum Hall Effect Resources with Additional Information Robert B. Laughlin Photo Courtesy of LLNL Robert B. Laughlin shared the 1998 Nobel Prize in Physics with Horst...
Quantum Spin Hall Effect in Silicene
Liu, Cheng-Cheng; Yao, Yugui
2011-01-01
Recent years have witnessed great interest in the quantum spin Hall effect (QSHE) which is a new quantum state of matter with nontrivial topological property due to the scientific importance as a novel quantum state and the technological applications in spintronics. Taking account of Si, Ge significant importance as semiconductor material and intense interest in the realization of QSHE for spintronics, here we investigate the spin-orbit opened energy gap and the band topology in recently synthesized silicene using first-principles calculations. We demonstrate that silicene with topologically nontrivial electronic structures can realize QSHE by exploiting adiabatic continuity and direct calculation of the Z2 topological invariant. We predict that QSHE in silicene can be observed in an experimentally accessible low temperature regime with the spin-orbit band gap of 1.55 meV, much higher than that of graphene due to large spin-orbit coupling and the low-buckled structure. Furthermore, we find that the gap will i...
Imaging transport resonances in the quantum Hall effect
Steele, Gary Alexander
2006-01-01
We image charge transport in the quantum Hall effect using a scanning charge accumulation microscope. Applying a DC bias voltage to the tip induces a highly resistive ring-shaped incompressible strip (IS) in a very high ...
Observation of the Integer Quantum Hall Effect in Record High...
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the Integer Quantum Hall Effect in Record High-Mobility Uniform Wafer-Scale Epitaxial Graphene Films Grown on the Si-Face of 6H-SiC(0001). Citation Details In-Document Search...
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.
2010-03-19
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.
Yannouleas, Constantine
quantum Hall effect FQHE in two-dimensional 2D semiconductor heterostruc- tures in the presence of a high in finite 2D electronic systems, such as semiconductor quantum dots QDs under high B, ledEdge states in graphene quantum dots: Fractional quantum Hall effect analogies and differences
Scalar spin chirality and quantum hall effect on triangular lattices
Martin, Ivar [Los Alamos National Laboratory; Batista, Cristian D [Los Alamos National Laboratory
2008-01-01
We study the Kondo Lattice and Hubbard models on a triangular lattice for band filling factor 3/4. We show that a simple non-coplanar chiral spin ordering (scalar spin chirality) is naturally realized in both models due to perfect nesting of the fermi surface. The resulting triple-Q magnetic ordering is a natural counterpart of the collinear Neel ordering of the half-filled square lattice Hubbard model. We show that the obtained chiral phase exhibits a spontaneous quantum Hall-effect with {sigma}{sub xy} = e{sup 2}/h.
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.
2010-03-19
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 anomalous Hall effect with cold atoms trapped in a square lattice
Liu, Xiong-Jun; Liu, Xin; Wu, Congjun; Sinova, Jairo
2010-01-01
We propose an experimental scheme to realize the quantum anomalous Hall effect in an anisotropic square optical lattice which can be generated from available experimental setups of double-well lattices with minor modifications. A periodic gauge...
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 ...
The Hausdorff dimension of fractal sets and fractional quantum Hall effect
Wellington da Cruz
2003-05-27
We consider Farey series of rational numbers in terms of {\\it fractal sets} labeled by the Hausdorff dimension with values defined in the interval 1$ $$ < $$ $$h$$ $$ <$$ $$ 2$ and associated with fractal curves. Our results come from the observation that the fractional quantum Hall effect-FQHE occurs in pairs of {\\it dual topological quantum numbers}, the filling factors. These quantum numbers obey some properties of the Farey series and so we obtain that {\\it the universality classes of the quantum Hall transitions are classified in terms of $h$}. The connection between Number Theory and Physics appears naturally in this context.
Coulomb Oscillations and Hall Effect in Quasi-2D Graphite Quantum Dots
McEuen, Paul L.
Coulomb Oscillations and Hall Effect in Quasi-2D Graphite Quantum Dots J. Scott Bunch, Yuval Yaish-temperature electrical transport measurements on gated, quasi-2D graphite quantum dots. In devices with low contact of graphene, a zero band gap semiconductor with two linearly dispersing bands that touch at the corners
Analytic calculations of trial wave functions of the fractional quantum Hall effect on the sphere
Carmem Lucia de Souza Batista; Dingping Li
1996-07-24
We present a framework for the analytic calculations of the hierarchical wave functions and the composite fermion wave functions in the fractional quantum Hall effect on the sphere by using projective coordinates. Then we calculate the overlaps between these two wave functions at various fillings and small numbers of electrons. We find that the overlaps are all most equal to one. This gives a further evidence that two theories of the fractional quantum Hall effect, the hierarchical theory and the composite fermion theory, are physically equivalent.
Igor A. Shovkovy; Lifang Xia
2015-08-18
By making use of the generalized Landau-level representation (GLLR) for the quasiparticle propagator, we study the effect of screening on the properties of the quantum Hall states with integer filling factors in graphene. The analysis is performed in the low-energy Dirac model in the improved rainbow approximation, in which the long-range Coulomb interaction is modified by the one-loop static screening effects in the presence of a background magnetic field. By utilizing a rather general ansatz for the propagator, in which all dynamical parameters are running functions of the Landau-level index $n$, we derive a self-consistent set of the Schwinger-Dyson (gap) equations and solve them numerically. The explicit solutions demonstrate that static screening leads to a substantial suppression of the gap parameters in the quantum Hall states with a broken $U(4)$ flavor symmetry. The temperature dependence of the energy gaps is also studied. The corresponding results mimic well the temperature dependence of the activation energies measured in experiment. It is also argued that, in principle, the Landau-level running of the quasiparticle dynamical parameters could be measured via optical studies of the integer quantum Hall states.
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
Fractional quantum Hall effect and insulating phase of Dirac electrons in graphene
Andrei, Eva Y.
semiconductor analogue3 . As a third distinguishing feature of graphene, it has been conjectured of graphene in terms of a two-dimensional (2D) zero-bandgap semiconductor with low energy excitations repreLETTERS Fractional quantum Hall effect and insulating phase of Dirac electrons in graphene Xu Du1
Quantum Spin Hall Eect May 9, 2011
Hall Eect Quantum Spin Hall Eect in Graphene QSHE in quantum well QSHE in strained semiconductor Tim Quantum Spin Hall Eect in Graphene QSHE in quantum well QSHE in strained semiconductor Tim Hsieh Quantum Hsieh Quantum Spin Hall Eect #12;Integer Quantum Hall Eect (IQHE) 2D electron gas at low temperature
Haldane Quantum Hall Effect for Light in a Dynamically Modulated Array of Resonators
Minkov, Momchil
2015-01-01
Topological insulators have attracted abundant attention for a variety of reasons -- notably, the possibility for lossless energy transport through edge states `protected' against disorder. Topological effects like the Quantum Hall state can be induced through a gauge field, which is however hard to create in practice, especially for charge-neutral particles. One way to induce an effective gauge potential is through a dynamic, time-periodic modulation of the lattice confining such particles. In this way, the Haldane Quantum Hall effect was recently observed in a cold atom system. Here, we show how this same effect can be induced for light confined to a lattice of identical optical resonators, using an on-site modulation of the resonant frequencies. We further demonstrate the existence of one-directional edge states immune to back-scattering losses, and discuss the possibilities for a practical implementation, which would enable slow-light devices of unprecedented quality.
Haldane Quantum Hall Effect for Light in a Dynamically Modulated Array of Resonators
Momchil Minkov; Vincenzo Savona
2015-07-16
Topological insulators have attracted abundant attention for a variety of reasons -- notably, the possibility for lossless energy transport through edge states `protected' against disorder. Topological effects like the Quantum Hall state can be induced through a gauge field, which is however hard to create in practice, especially for charge-neutral particles. One way to induce an effective gauge potential is through a dynamic, time-periodic modulation of the lattice confining such particles. In this way, the Haldane Quantum Hall effect was recently observed in a cold atom system. Here, we show how this same effect can be induced for light confined to a lattice of identical optical resonators, using an on-site modulation of the resonant frequencies. We further demonstrate the existence of one-directional edge states immune to back-scattering losses, and discuss the possibilities for a practical implementation, which would enable slow-light devices of unprecedented quality.
Shovkovy, Igor A
2015-01-01
By making use of the generalized Landau-level representation (GLLR) for the quasiparticle propagator, we study the effect of screening on the properties of the quantum Hall states with integer filling factors in graphene. The analysis is performed in the low-energy Dirac model in the improved rainbow approximation, in which the long-range Coulomb interaction is modified by the one-loop static screening effects in the presence of a background magnetic field. By utilizing a rather general ansatz for the propagator, in which all dynamical parameters are running functions of the Landau-level index $n$, we derive a self-consistent set of the Schwinger-Dyson (gap) equations and solve them numerically. The explicit solutions demonstrate that static screening leads to a substantial suppression of the gap parameters in the quantum Hall states with a broken $U(4)$ flavor symmetry. The temperature dependence of the energy gaps is also studied. The corresponding results mimic well the temperature dependence of the activa...
Non-abelian fractional quantum hall effect for fault-resistant...
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decoherence processes without additional error-correction. It is believed that the low energy excitations of the so-called 52 fractional quantum Hall (FQH) state may obey...
Excitonic gap, phase transition, and quantum Hall effect in graphene
V. P. Gusynin; V. A. Miransky; S. G. Sharapov; I. A. Shovkovy
2006-11-23
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.
Magnetic Topological Insulator and Quantum Anomalous Hall Effect
Kou, Xufeng
2015-01-01
magnetic field and a high mobility material with a good 2D confinement [magnetic TI system, the competition between the FM exchange field and the quantum confinement-
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)
2014-08-21
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; Lee, Ching-Hua; Thomale, Ronny; Qi, Xiao-Liang; Devereaux, Thomas P
2015-06-11
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 dualsmore »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.« less
Quantum Hall effect in HgTe quantum wells at nitrogen temperatures
Kozlov, D. A. Kvon, Z. D.; Mikhailov, N. N.; Dvoretskii, S. A.; Weishäupl, S.; Krupko, Y.; Portal, J.-C.
2014-09-29
We report on the observation of quantized Hall plateaus in a system of two-dimensional Dirac fermions, implemented in a 6.6?nm HgTe quantum well at magnetic fields up to 34?T at nitrogen temperatures. The activation energies determined from the temperature dependence of the longitudinal resistivity are found to be almost equal for the filling factors ? of 1 and 2. This indicates that the large values of the g-factor (about 30–40) remain unchanged at very strong magnetic fields.
Quantum Hall effect today V. J. Goldman 1
Goldman, Vladimir J.
of the many-particle wave function is equal to the number of the flux quanta, in mean field theory CFs can often be thought of as electrons each binding 2p0 of applied B. Thus CFs experience effective magnetic zero-field metal of CFs. Also, the FQHE of inter- acting electrons at = i 2i+1 maps onto the IQHE
Igor Romanovsky; Constantine Yannouleas; Uzi Landman
2009-01-15
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
2008-08-28
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.
Transport of surface states in the bulk quantum Hall effect Sora Cho Department of Physics, University of California, Santa Barbara, California 93106 Leon Balents Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 Matthew P. A. Fisher Institute for Theoretical
Hall Effect Gyrators and Circulators
Giovanni Viola; David P. DiVincenzo
2014-03-04
The electronic circulator, and its close relative the gyrator, are invaluable tools for noise management and signal routing in the current generation of low-temperature microwave systems for the implementation of new quantum technologies. The current implementation of these devices using the Faraday effect is satisfactory, but requires a bulky structure whose physical dimension is close to the microwave wavelength employed. The Hall effect is an alternative non-reciprocal effect that can also be used to produce desired device functionality. We review earlier efforts to use an ohmically-contacted four-terminal Hall bar, explaining why this approach leads to unacceptably high device loss. We find that capacitive coupling to such a Hall conductor has much greater promise for achieving good circulator and gyrator functionality. We formulate a classical Ohm-Hall analysis for calculating the properties of such a device, and show how this classical theory simplifies remarkably in the limiting case of the Hall angle approaching 90 degrees. In this limit we find that either a four-terminal or a three-terminal capacitive device can give excellent circulator behavior, with device dimensions far smaller than the a.c. wavelength. An experiment is proposed to achieve GHz-band gyration in millimetre (and smaller) scale structures employing either semiconductor heterostructure or graphene Hall conductors. An inductively coupled scheme for realising a Hall gyrator is also analysed.
Fractional Quantum Hall States in Graphene
Ahmed Jellal; Bellati Malika
2011-04-27
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 \
Geometric adiabatic transport in quantum Hall states
Semyon Klevtsov; Paul Wiegmann
2015-08-22
We argue that in addition to the Hall conductance and the nondissipative component of the viscous tensor, there exists a third independent transport coefficient, which is precisely quantized. It takes constant values along quantum Hall plateaus. We show that the new coefficient is the Chern number of a vector bundle over moduli space of surfaces of genus 2 or higher and therefore cannot change continuously along the plateau. As such, it does not transpire on a sphere or a torus. In the linear response theory, this coefficient determines intensive forces exerted on electronic fluid by adiabatic deformations of geometry and represents the effect of the gravitational anomaly. We also present the method of computing the transport coefficients for quantum Hall states.
Engineering of Quantum Hall Effect from Type IIA String Theory on The K3 Surface
Adil Belhaj; Antonio Segui
2010-07-02
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.
Composite Fermions and the First-Landau-Level Fine Structure of the Fractional Quantum Hall Effect
Haxton, W C
2015-01-01
We show that an alternative use of operators introduced in 1996 by Ginocchio and Haxton (GH) leads to a simple representation of the wave functions for the fractional quantum Hall effect, as non-interacting quasi-electrons (or composite fermions) fully filling fine-structure subshells within the first Landau level (FLL). In the present GH2 construction each shell corresponds to a distinct quasi-electron, constructed explicitly on both the sphere and the plane as vector products of spinors creating an electron and one unit of magnetic flux, a structure we argue follows from the coordinate scale invariance of the Coulomb potential. The quasi-electrons are eigenstates of angular momentum L and Lz. The hierarchy and conjugate states are the lowest-energy filled-shell configurations of these quasi-electrons, where the energy "counting" is related to Haldane's pseudo-potential. The construction yields a correspondence between the quasi-particle representation of the incompressible FLL state of filling p/(2p +1) and...
Engineering quantum anomalous/valley Hall states in graphene...
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Engineering quantum anomalousvalley Hall states in graphene via metal-atom adsorption: Anab-initiostudy Prev Next Title: Engineering quantum anomalousvalley Hall states in...
de Nova, J R M
2015-01-01
The work is divided in three parts. We devote the first part to the study of analog Hawking radiation in Bose-Einstein condensates. We study numerically the birth of a sonic black hole in an outcoupled Bose-Einstein condensate after relaxing the confinement provided by an optical lattice. We also study possible signatures of spontaneous Hawking radiation. We propose that the violation of CS inequalities is a smoking gun of the presence of the Hawking effect. We compare this criterion with the presence of entaglement, finding that both are equivalent under usual assumptions. Finally, we study a different gravitational analogue: the so-called black-hole laser. The most interesting result is the appearance of a regime of continuous and periodic emission of solitons, providing the most strong analogue with optical lasers. In the second part, we analyze the effect of the introduction of a short Bragg pulse in a thermal cloud. We show that the induced periodic density pattern decays to the equilibrium profile. Howe...
J. R. M. de Nova
2015-11-11
The work is divided in three parts. We devote the first part to the study of analog Hawking radiation in Bose-Einstein condensates. We study numerically the birth of a sonic black hole in an outcoupled Bose-Einstein condensate after relaxing the confinement provided by an optical lattice. We also study possible signatures of spontaneous Hawking radiation. We propose that the violation of CS inequalities is a smoking gun of the presence of the Hawking effect. We compare this criterion with the presence of entaglement, finding that both are equivalent under usual assumptions. Finally, we study a different gravitational analogue: the so-called black-hole laser. The most interesting result is the appearance of a regime of continuous and periodic emission of solitons, providing the most strong analogue with optical lasers. In the second part, we analyze the effect of the introduction of a short Bragg pulse in a thermal cloud. We show that the induced periodic density pattern decays to the equilibrium profile. However, instead of the usual collisional relaxation, the mechanism responsible for the decay is the thermal disorder of the particles, with a characteristic time that only depends on the temperature. We find a very good agreement with actual experimental data. In the last part, we switch to a very different system: the $\
Precise adiabatic transport and geometry of quantum Hall states
Klevtsov, Semyon
2015-01-01
We argue that in addition to the Hall conductance and the non-dissipative component of the viscous tensor there exists a third independent kinetic coefficient which is precise on the quantum Hall plateaus. We show that the new coefficient is the Chern number over moduli space of surfaces of genus two or higher and therefore is precise. As such it does not transpire on a sphere or a torus. In the linear response theory this coefficient determines intensive forces exerted on electronic fluid by adiabatic deformations of geometry and represents the effect of the gravitational anomaly. We also present the method of computing the transport coefficients for quantum Hall states.
Unconventional Sequence of Fractional Quantum Hall
Yacoby, Amir
Unconventional Sequence of Fractional Quantum Hall States in Suspended Graphene Benjamin E. Feldman- netic field B to a two-dimensional elec- tron gas (2DEG) gives rise to flat energy bands called Landau
Huang, Yi-Zhi
Quantum Hall systems Representation theory of vertex operator algebras Applications The end Quantum Science, CAS #12;Quantum Hall systems Representation theory of vertex operator algebras Applications to a fundamental conjecture #12;Quantum Hall systems Representation theory of vertex operator algebras Applications
Huang, Yi-Zhi
Quantum Hall systems Representation theory of vertex operator algebras Applications The end Quantum;Quantum Hall systems Representation theory of vertex operator algebras Applications The end Outline 1 An approach to a fundamental conjecture #12;Quantum Hall systems Representation theory of vertex operator
Quantum Hall Effect in n-p-n and n-2D Topological Insulator-n Junctions G. M. Gusev,1
Gusev, Guennady
Quantum Hall Effect in n-p-n and n-2D Topological Insulator-n Junctions G. M. Gusev,1 A. D. Levin,1 TI) with locally controlled density allowing n-p-n and n-2D TI-n junctions. The resistance reveals quantization in the graphene p-n [1] or n-p-n [2,3] junctions, which has been attributed to chiral edge states
Eliashvili, M
1994-01-01
We've defined a non-unitary similarity transformation interconnecting the spectrum generating quantum operators and state vectors of integral and fractional QHE. This transformation corresponds to the introduction of the complex Chern-Simons gauge potentials, in terms of wich the field- theoretic formulation of FQHE can be developed. As a first step the second quantized form of Laughlin wave function is given.
Constantine Yannouleas; Igor Romanovsky; Uzi Landman
2010-09-13
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.
Zhao, Weiwei
The quantum anomalous Hall (QAH) effect is predicted to possess, at a zero magnetic field, chiral edge channels that conduct a spin polarized current without dissipation. While edge channels have been observed in previous ...
Comments on Hall transport from effective actions
Felix M. Haehl; Mukund Rangamani
2015-01-18
We consider parity-odd transport in 2+1 dimensional charged fluids restricting attention to the class of non-dissipative fluids. We show that there is a two parameter family of such non-dissipative fluids which can be derived from an effective action, in contradistinction with a four parameter family that can be derived from an entropy current analysis. The effective action approach allows us to extract the adiabatic transport data, in particular the Hall viscosity and Hall conductivity amongst others, in terms of the thermodynamic functions that enter as 'coupling constants'. Curiously, we find that Hall viscosity is forced to vanish, whilst the Hall conductivity is generically a non-vanishing function of thermodynamic data determined in terms of the hydrodynamic couplings.
Admittance of multiterminal quantum Hall conductors at kilohertz frequencies
Hernández, C.; Consejo, C.; Chaubet, C.; Degiovanni, P.
2014-03-28
We present an experimental study of the low frequency admittance of quantum Hall conductors in the [100?Hz, 1?MHz] frequency range. We show that the frequency dependence of the admittance of the sample strongly depends on the topology of the contacts connections. Our experimental results are well explained within the Christen and Büttiker approach for finite frequency transport in quantum Hall edge channels taking into account the influence of the coaxial cables capacitance. In the Hall bar geometry, we demonstrate that there exists a configuration in which the cable capacitance does not influence the admittance measurement of the sample. In this case, we measure the electrochemical capacitance of the sample and observe its dependence on the filling factor.
Gapless layered three-dimensional fractional quantum Hall states Michael Levin1
2D , anisotropic three-dimensional 3D electron systems--such as multilayer systems in a perpen of experiments on 3D semiconductor multilayers have explored the behavior of stacked integer quantum Hall states effect in graphene,2023 and future pros- pects for graphene multilayers, provides further impetus
theory governing the low-energy behavior of graphene in an applied magnetic field. Initially, we consider perhaps remain paramagnetic due to strong disorder. In an attempt to access the latter regime where the role of exchange is strongly suppressed by disorder, we apply Hartree theory to study the effects
Parallel Hall effect from 3D single-component metamaterials
Kern, Christian; Wegener, Martin
2015-01-01
We propose a class of three-dimensional metamaterial architectures composed of a single doped semiconductor (e.g., n-Si) in air or vacuum that lead to unusual effective behavior of the classical Hall effect. Using an anisotropic structure, we numerically demonstrate a Hall voltage that is parallel---rather than orthogonal---to the external static magnetic-field vector ("parallel Hall effect"). The sign of this parallel Hall voltage can be determined by a structure parameter. Together with the previously demonstrated positive or negative orthogonal Hall voltage, we demonstrate four different sign combinations
A spin-filter made of quantum anomalous Hall insulator nanowires
Wu, Jiansheng
2014-07-28
Topological end states (TES) in quantum anomalous Hall insulator nanowires can induce tunneling within the gap. Such TES are spin polarized, thus the induced current is spin polarized as well, which can be used to construct a spin-filter applied in spintronics. An interferometry device is designed to control the polarized current as well. The advantage and finite size effect on this system are discussed.
Crystalline phases of graphene quantum Hall polariton fluids
Francesco M. D. Pellegrino; Vittorio Giovannetti; Allan H. MacDonald; Marco Polini
2015-05-26
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.
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
Observation of Chiral Heat Transport in the Quantum Hall Regime G. Granger,1
Eisenstein, Jim
Observation of Chiral Heat Transport in the Quantum Hall Regime G. Granger,1 J. P. Eisenstein,1 and J. L. Reno2 1 Condensed Matter Physics, California Institute of Technology, Pasadena, California; published 23 February 2009) Heat transport in the quantum Hall regime is investigated using micron
Hall effect at a tunable metal-insulator transition
Teizer, Winfried; Hellman, F.; Dynes, RC.
2003-01-01
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...
Pulsed field UCu5 Hall effect and magnetization (I)
Mcdonald, Ross D [Los Alamos National Laboratory; Ayala - Valenzuela, Oscar E [Los Alamos National Laboratory; Ben, Ueland G [Los Alamos National Laboratory; Corneliu, Miclea [Los Alamos National Laboratory; Movshovich, R [Los Alamos National Laboratory; Tompson, J. D. [Los Alamos National Laboratory; Bauer, E [Los Alamos National Laboratory; Batista, C. D. [Los Alamos National Laboratory; Martin, I [Los Alamos National Laboratory
2011-01-14
Prior studies of UCu{sub 5} identified the material as undergoing antiferromagnetic ordering at a temperature of 15 K with a subsequent reduction of the electronic density of states, evident as sharp upturn in resistance, at 1.4 K. High field magnetization measurements indicate a complex temperature-field phase diagram comprising of numerous phases below 15 K up and up to 60 T, with NMR and neutron measurements identifying both simple anitferromagnetic and 4Q-magnetic structures at low fields. The purpose of our investigations is to identify the possibly strong coupling between the itinerant electrons and the local spin structures, such as quantum amplification of the Hall effect due to (field induced) non-colinear spin textures. Comparison with prior literature indicates the sensitivity of the phase stability of the different spin textures to composition and sample preparation. However, the 'simplified' phase diagram of this composition offers the possibility of exploring, anomalous Hall properties arising from a field induced non-colinear spin texture over a wide range of temperatures and magnetic fields.
AC-magnetotransport of a 2DEG in the quantum Hall regime
Hernández, C.; Chaubet, C.
2014-05-15
In this paper we present an ac-magneto-transport study of a two-dimensional electron gas (2DEG) in the quantum Hall effect (QHE) regime, for frequencies in the range [100Hz, 1MHz]. We present a new approach to understand admittance measurements based in the Landauer-Buttiker formalism for QHE edge channels and taking into account the capacitance and the topology of the cables connected to the contacts used in the measurements. Our model predicts an universal behavior with the a-dimensional parameter RC? where R is the 2 wires resistance of the 2DEG, C the capacitance cables and the angular frequency, in agreement with experiments.
Snizhko, K.
In a recent experimental paper [Bid et al., Nature 466, 585 (2010)] a qualitative confirmation of the existence of upstream neutral modes at the ? = 2/3 quantum Hall edge was reported. Using the chiral Luttinger liquid ...
SU(3) and SU(4) Singlet Quantum Hall States at v = 2/3
Wu, Fengcheng
We report on an exact diagonalization study of fractional quantum Hall states at a filling factor of ? = 2/3 in a system with a fourfold degenerate n = 0 Landau level and SU(4) symmetric Coulomb interactions. Our investigation ...
Unconventional Quantum Hall Effect and Tunable Spin Hall Effect...
Office of Scientific and Technical Information (OSTI)
Date: 2013-02-01 OSTI Identifier: 1102031 Type: Publisher's Accepted Manuscript Journal Name: Physical Review Letters Additional Journal Information: Journal Volume: 110;...
Anomalous Hall effect in a two-dimensional electron gas
Nunner, Tamara S.; Sinitsyn, N. A.; Borunda, Mario F.; Dugaev, V. K.; Kovalev, A. A.; Abanov, Artem; Timm, Carsten; Jungwirth, T.; Inoue, Jun-ichiro; MacDonald, A. H.; Sinova, Jairo.
2007-01-01
The anomalous Hall effect in a magnetic two-dimensional electron gas with Rashba spin-orbit coupling is studied within the Kubo-Streda formalism in the presence of pointlike potential impurities. We find that all contributions ...
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.
2010-03-16
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.
Signatures of Fractional Exclusion Statistics in the Spectroscopy of Quantum Hall Droplets
Cooper, Nigel R.; Simon, Steven H.
2015-03-09
of quasiparticle excitations with unconventional quantum statistics. The archetypal example is the fractional, “anyonic”, quantum statistics predicted for the quasiparticles of the fractional quantum Hall phases[1, 2]. While experiments on semiconductor devices... substantially from proposals to measure the fractional braiding statistics of quasiholes[7–9], notably by not re- quiring local time-dependent potentials for the adiabatic manipulation of the positions of the quasiholes. We have in mind a fast rotating gas...
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)
2014-04-28
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.
Fractional Quantum Hall Filling Factors from String Theory using Toric Geometry
Belhaj, A; Idrissi, M El; Manaut, B; Sebbar, A; Sedra, M B
2015-01-01
Using toric Cartan matrices as abelian gauge charges, we present a class of stringy fractional quantum Hall effect (FQHE) producing some recent experimental observed filling factor values. More precisely, we derive the corresponding Chern-Simons type models from M-theory compactified on four complex dimensional hyper-K\\"{a}hler manifolds X^4. These manifolds, which are viewed as target spaces of a particular N=4 sigma model in two dimensions, are identified with the cotangent bundles over intersecting 2-dimensional toric varieties V_i^2 according to toric Cartan matrices. Exploring results of string dualities, the presented FQHE can be obtained from D6-banes wrapping on such intersecting toric varieties interacting with R-R gauge fields. This string theory realization provides a geometric interpretation of the filling factors in terms of toric and Euler characteristic topological data of the compactified geometry. Concretely, explicit bilayer models are worked out in some details.
Color Glass Condensates in dense quark matter and quantum Hall states of gluons
Aiichi Iwazaki
2006-04-26
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.
Inverse spin Hall effect in Pt/(Ga,Mn)As
Nakayama, H.; Chen, L.; Chang, H. W.; Ohno, H.; Matsukura, F.
2015-06-01
We investigate dc voltages under ferromagnetic resonance in a Pt/(Ga,Mn)As bilayer structure. A part of the observed dc voltage is shown to originate from the inverse spin Hall effect. The sign of the inverse spin Hall voltage is the same as that in Py/Pt bilayer structure, even though the stacking order of ferromagnetic and nonmagnetic layers is opposite to each other. The spin mixing conductance at the Pt/(Ga,Mn)As interface is determined to be of the order of 10{sup 19?}m{sup ?2}, which is about ten times greater than that of (Ga,Mn)As/p-GaAs.
Study of the effects of guide field on Hall reconnection
Tharp, T. D.; Yamada, M.; Ji, H.; Lawrence, E.; Dorfman, S.; Myers, C.; Yoo, J.; Huang, Y.-M.; Bhattacharjee, A.
2013-05-15
The results from guide field studies on the Magnetic Reconnection Experiment (MRX) are compared with results from Hall magnetohydrodynamic (HMHD) reconnection simulation with guide field. The quadrupole field, a signature of two-fluid reconnection at zero guide field, is modified by the presence of a finite guide field in a manner consistent with HMHD simulation. The modified Hall current profile contains reduced electron flows in the reconnection plane, which quantitatively explains the observed reduction of the reconnection rate. The present results are consistent with the hypothesis that the local reconnection dynamics is dominated by Hall effects in the collisionless regime of the MRX plasmas. While very good agreement is seen between experiment and simulations, we note that an important global feature of the experiments, a compression of the guide field by the reconnecting plasma, is not represented in the simulations.
Lo, Shun-Tsung; Hsu, Chang-Shun [Graduate Institute of Applied Physics, National Taiwan University, Taipei 10617, Taiwan (China); Lin, Y. M.; Lin, S.-D.; Lee, C. P. [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Ho, Sheng-Han; Chuang, Chiashain; Wang, Yi-Ting [Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Liang, C.-T. [Graduate Institute of Applied Physics, National Taiwan University, Taipei 10617, Taiwan (China); Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China)
2014-07-07
We study interference and interactions in an InAs/InAsSb two-dimensional electron system. In such a system, spin-orbit interactions are shown to be strong, which result in weak antilocalization (WAL) and thereby positive magnetoresistance around zero magnetic field. After suppressing WAL by the magnetic field, we demonstrate that classical positive magnetoresistance due to spin-orbit coupling plays a role. With further increasing the magnetic field, the system undergoes a direct insulator-quantum Hall transition. By analyzing the magnetotransport behavior in different field regions, we show that both electron-electron interactions and spin-related effects are essential in understanding the observed direct transition.
Effects of Enhanced Eathode Electron Emission on Hall Thruster Operation
Y. Raitses, A. Smirnov and N. J. Fisch
2009-04-24
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.
Kane, Charles
magnetic field B. The model could be rele- vant for semiconductor quantum wires, ropes of carbon nanotubes in which interwire Josephson, charge- and spin-density wave, and single-particle couplings are irrele- vant
Orbitronics: the Intrinsic Orbital Hall Effect in p-Doped Silicon
Bernevig, B.Andrei; Hughes, Taylor L.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.
2010-01-15
The spin Hall effect depends crucially on the intrinsic spin-orbit coupling of the energy band. Because of the smaller spin-orbit coupling in silicon, the spin Hall effect is expected to be much reduced. We show that the electric field in p-doped silicon can induce a dissipationless orbital current in a fashion reminiscent of the spin Hall effect. The vertex correction due to impurity scattering vanishes and the effect is therefore robust against disorder. The orbital Hall effect can lead to the accumulation of local orbital momentum at the edge of the sample, and can be detected by the Kerr effect.
THE BYSTANDER EFFECT Eric J. Hall*
high- and low-LET radiations but it is usually larger for densely ionizing radiation such as alpha than the cell and this could make a simple linear extrapolation of radiation risks from high to low in this effect was sparked by the report of Nagasawa and Little (1992) that, following a low dose of alpha
Martin, L. N.; Dmitruk, P.; Gomez, D. O.
2010-11-15
In this work we numerically test a model of Hall magnetohydrodynamics in the presence of a strong mean magnetic field: the reduced Hall magnetohydrodynamic model (RHMHD) derived by [Gomez et al., Phys. Plasmas 15, 102303 (2008)] with the addition of weak compressible effects. The main advantage of this model lies in the reduction of computational cost. Nevertheless, up until now the degree of agreement with the original Hall MHD system and the range of validity in a regime of turbulence were not established. In this work direct numerical simulations of three-dimensional Hall MHD turbulence in the presence of a strong mean magnetic field are compared with simulations of the weak compressible RHMHD model. The results show that the degree of agreement is very high (when the different assumptions of RHMHD, such as spectral anisotropy, are satisfied). Nevertheless, when the initial conditions are isotropic but the mean magnetic field is maintained strong, the results differ at the beginning but asymptotically reach a good agreement at relatively short times. We also found evidence that the compressibility still plays a role in the dynamics of these systems, and the weak compressible RHMHD model is able to capture these effects. In conclusion the weak compressible RHMHD model is a valid approximation of the Hall MHD turbulence in the relevant physical context.
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)
2014-07-15
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.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Zhou, Miao; Ming, Wenmei; Liu, Zheng; Wang, Zhengfei; Yao, Yugui; Liu, Feng
2014-11-19
For potential applications in spintronics and quantum computing, it is desirable to place a quantum spin Hall insulator [i.e., a 2D topological insulator (TI)] on a substrate while maintaining a large energy gap. Here, we demonstrate a unique approach to create the large-gap 2D TI state on a semiconductor surface, based on first-principles calculations and effective Hamiltonian analysis. We show that when heavy elements with strong spin orbit coupling (SOC) such as Bi and Pb atoms are deposited on a patterned H-Si(111) surface into a hexagonal lattice, they exhibit a 2D TI state with a large energy gap of ?0.5more »eV. The TI state arises from an intriguing substrate orbital filtering effect that selects a suitable orbital composition around the Fermi level, so that the system can be matched onto a four-band effective model Hamiltonian. Furthermore, it is found that within this model, the SOC gap does not increase monotonically with the increasing strength of SOC. These interesting results may shed new light in future design and fabrication of large-gap topological quantum states.« less
Zhou, Miao; Ming, Wenmei; Liu, Zheng; Wang, Zhengfei; Yao, Yugui; Liu, Feng
2014-11-19
For potential applications in spintronics and quantum computing, it is desirable to place a quantum spin Hall insulator [i.e., a 2D topological insulator (TI)] on a substrate while maintaining a large energy gap. Here, we demonstrate a unique approach to create the large-gap 2D TI state on a semiconductor surface, based on first-principles calculations and effective Hamiltonian analysis. We show that when heavy elements with strong spin orbit coupling (SOC) such as Bi and Pb atoms are deposited on a patterned H-Si(111) surface into a hexagonal lattice, they exhibit a 2D TI state with a large energy gap of ?0.5 eV. The TI state arises from an intriguing substrate orbital filtering effect that selects a suitable orbital composition around the Fermi level, so that the system can be matched onto a four-band effective model Hamiltonian. Furthermore, it is found that within this model, the SOC gap does not increase monotonically with the increasing strength of SOC. These interesting results may shed new light in future design and fabrication of large-gap topological quantum states.
Hall Effect Thruster Plasma Plume Characterization with Probe Measurements and Self-Similar Fluid
Carlos III de Madrid, Universidad
Hall Effect Thruster Plasma Plume Characterization with Probe Measurements and Self-Similar Fluid§ Universidad Polit´ecnica de Madrid, Madrid 28040 Spain A characterization of the far-field plasma plume of two Hall effect thrusters was per- formed by means of a comparison between experimental plasma properties
Transport properties in bilayer Quantum Hall systems in the presence of a topological defect
Gerardo Cristofano; Vincenzo Marotta; Adele Naddeo; Giuliano Niccoli
2006-06-27
Following a suggestion given in Phys. Lett. B 571(2003) 621, we show how a bilayer Quantum Hall system at fillings nu =1/p+1 can exhibit a point-like topological defect in its edge state structure. Indeed our CFT theory for such a system, the Twisted Model (TM), gives rise in a natural way to such a feature in the twisted sector. Our results are in agreement with recent experimental findings (Phys. Rev. B 72 (2005) 041305) which evidence the presence of a topological defect in the transport properties of the bilayer system.
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) hot-pressed composite, denoted as M26, was used as the insulating chamber wall for a xenon plasma Hall expansion of BN in the amorphous silica matrix. Exfoliation accompanied the microcracking in BN and resulted
Liang, Chi-Te; Lin, Li-Hung; Chen, Kuang Yao; Lo, Shun-Tsung; Wang, Yi-Ting; Lo, Dong-Sheng; Kim, Gil-Ho; Chang, Yuan Huei; Ochiai, Yuichi; Aoki, Nobuyuki; Chen, Jeng Chung; Lin, Yiping; Huang, Chun Feng; Lin, Sheng-Di; Richie, David A
2011-02-11
, Nicholls JT, Frost JEF, Linfield EH, Pepper M, Ford CJB, Ritchie DA, Jones GAC, Kogan E, Kaveh M: Magnetic-field-induced insulator-quantum Hall-insulator transition in a disordered two- dimensional electron gas. J Phys Condens Matter 1994, 6:4763. 6...
Investigation of magnetic proximity effect in Ta/YIG bilayer Hall bar structure
Yang, Yumeng [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583 (Singapore); Institute of Materials Research and Engineering, A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Wu, Baolei; Wu, Yihong, E-mail: elewuyh@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583 (Singapore); Yao, Kui; Shannigrahi, Santiranjan [Institute of Materials Research and Engineering, A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Zong, Baoyu [Temasek Laboratories, National University of Singapore, T-Lab Building, 5A Engineering Drive 1, 09-02, Singapore 117411 (Singapore)
2014-05-07
In this work, the investigation of magnetic proximity effect was extended to Ta which has been reported to have a negative spin Hall angle. Magnetoresistance (MR) and Hall measurements for in-plane and out-of-plane applied magnetic field sweeps were carried out at room temperature. The size of the MR ratio observed (?10{sup ?5}) and its magnetization direction dependence are similar to that reported in Pt/yttrium iron garnet, both of which can be explained by the spin Hall magnetoresistance theory. Additionally, a flip of magnetoresistance polarity is observed at 4?K in the temperature dependent measurements, which can be explained by the magnetic proximity effect induced anisotropic magnetoresistance at low temperature. Our findings suggest that both magnetic proximity effect and spin Hall magnetoresistance have contribution to the recently observed unconventional magnetoresistance effect.
Electroweak Hall Effect of Neutrino and Coronal Heating
Ishikawa, Kenzo
2015-01-01
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.
Zhao, Bao; Zhang, Jiayong; Wang, Yicheng; Yang, Zhongqin
2014-12-28
The electronic states and topological behaviors of Pt(Ni, Pd)-decorated silicene are investigated by using an ab-initio method. All the three kinds of the adatoms prefer hollow sites of the silicene, guaranteeing the Dirac cones unbroken. The Pt(Ni, Pd)-decorated silicene systems all present quantum valley Hall (QVH) states with the gap opened exactly at the Fermi level. The gaps of the QVH states can be increased substantially by applying a positive electric field. Very fascinating phase transitions from QVH to quantum spin Hall (QSH) and then to QVH again are achieved in the Pt/Ni-decorated silicene when a negative electric field is applied. The QSH state in the Pd case with a negative electric field is, however, quenched because of relatively larger Rashba spin-orbit coupling (SOC) than the intrinsic SOC in the system. Our findings may be useful for the applications of silicene-based devices in valleytronics and spintronics.
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
2015-02-09
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.
Borunda, M. F.; Liu, Xin; Kovalev, Alexey A.; Liu, Xiong-Jun; Jungwirth, T.; Sinova, Jairo.
2008-01-01
- conductor systems. B. Spin Hall effect The proposal of intrinsic spin Hall effect37 and the experi- mental observation of the effect ?both extrinsic and intrinsic?38 has generated a lot of interest in the semiconduc- tor spintronics community. Numerical...
Disorder effects in the anomalous Hall effect induced by Berry curvature RID B-5617-2009
Sinitsyn, NA; Niu, Q.; Sinova, Jairo; Nomura, K.
2005-01-01
sufficiently low Fermi level ?EF?h ,?kF?? the minor band becomes depleted and the transport is only in the major band. In this case the clean limit Hall current is jyx?clean? = e2Ex 2?2???1 ? 1?1 + ?kF??/h?2? . ?39? We address next the effects of impurity... 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 in geometrical optics,2 however, its...
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
Experimental evidences of a large extrinsic spin Hall effect in AuW alloy
Laczkowski, P.; Rojas-Sánchez, J.-C.
2014-04-07
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)
2011-11-28
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.
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.
2012-02-03
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
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 and complexity as the voltage is increased, and are reduced in severity with increasing flow rate. The `breathing
Manifestation of the spin Hall effect through charge-transport in the mesoscopic regime
Hankiewicz, EM; Molenkamp, LW; Jungwirth, T.; Sinova, Jairo.
2004-01-01
We study theoretically the manifestation of the spin Hall effect in a two-dimensional electronic system with Rashba spin-orbit coupling via dc-transport measurements in realistic mesoscopic H-shape structures. The Landauer-Buttiker formalism is used...
TL173L, TL173C LINEAR HALL-EFFECT SENSORS
Ida, Nathan
Sheet Page 1 of 3http://www.ionpool.net/arcade/irobot/tl173l.html #12;Recommended operating conditions Linear Hall-Effect Sensor Data Sheet Page 2 of 3http://www.ionpool.net/arcade/irobot/tl173l.html #12;last://www.ionpool.net/arcade/irobot/tl173l.html #12;
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)
2014-11-03
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.
Time-resolved dynamics of the spin Hall effect
Loss, Daniel
. GOSSARD AND D. D. AWSCHALOM* Center for Spintronics and Quantum Computation, University of Californiaorbit physics as well as a valuable capability for potential spintronics devices14 . One realization in spintronics devices, understanding dynamics on this timescale is critical for both physical and practical
Sheath oscillation characteristics and effect on near-wall conduction in a krypton Hall thruster
Zhang, Fengkui Kong, Lingyi; Li, Chenliang; Yang, Haiwei; Li, Wei
2014-11-15
Despite its affordability, the krypton Hall-effect thruster in applications always had problems in regard to performance. The reason for this degradation is studied from the perspective of the near-wall conductivity of electrons. Using the particle-in-cell method, the sheath oscillation characteristics and its effect on near-wall conduction are compared in the krypton and xenon Hall-effect thrusters both with wall material composed of BNSiO{sub 2}. Comparing these two thrusters, the sheath in the krypton-plasma thruster will oscillate at low electron temperatures. The near-wall conduction current is only produced by collisions between electrons and wall, thereby causing a deficiency in the channel current. The sheath displays spatial oscillations only at high electron temperature; electrons are then reflected to produce the non-oscillation conduction current needed for the krypton-plasma thruster. However, it is accompanied with intensified oscillations.
Realization of tunable spin-dependent splitting in intrinsic photonic spin Hall effect
Ling, Xiaohui [SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, and Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Laboratory for spin photonics, College of Physics and Microelectronic Science, Hunan University, Changsha 410082 (China); Department of Physics and Electronic Information Science, Hengyang Normal University, Hengyang 421002 (China); Yi, Xunong [SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, and Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Zhou, Xinxing; Liu, Yachao; Shu, Weixing; Wen, Shuangchun [Laboratory for spin photonics, College of Physics and Microelectronic Science, Hunan University, Changsha 410082 (China); Luo, Hailu, E-mail: hailuluo@hnu.edu.cn [SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, and Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Laboratory for spin photonics, College of Physics and Microelectronic Science, Hunan University, Changsha 410082 (China)
2014-10-13
We report the realization of tunable spin-dependent splitting in intrinsic photonic spin Hall effect. By breaking the rotational symmetry of a cylindrical vector beam, the intrinsic vortex phases that the two spin components of the vector beam carries, which is similar to the geometric Pancharatnam-Berry phase, are no longer continuous in the azimuthal direction, and leads to observation of spin accumulation at the opposite edge of the beam. Due to the inherent nature of the phase and independency of light-matter interaction, the observed photonic spin Hall effect is intrinsic. Modulating the topological charge of the vector beam, the spin-dependent splitting can be enhanced and the direction of spin accumulation is switchable. Our findings may provide a possible route for generation and manipulation of spin-polarized photons, and enables spin-based photonics applications.
Rivest, Christopher W. (Christopher Warren)
2006-01-01
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, ...
Hall-effect-controlled gas dynamics in protoplanetary disks. I. Wind solutions at the inner disk
Bai, Xue-Ning
2014-08-20
The gas dynamics of protoplanetary disks (PPDs) is largely controlled by non-ideal magnetohydrodynamic (MHD) effects including Ohmic resistivity, the Hall effect, and ambipolar diffusion. Among these the role of the Hall effect is the least explored and most poorly understood. In this series, we have included, for the first time, all three non-ideal MHD effects in a self-consistent manner to investigate the role of the Hall effect on PPD gas dynamics using local shearing-box simulations. In this first paper, we focus on the inner region of PPDs, where previous studies (Bai and Stone 2013; Bai 2013) excluding the Hall effect have revealed that the inner disk up to ?10 AU is largely laminar, with accretion driven by a magnetocentrifugal wind. We confirm this basic picture and show that the Hall effect modifies the wind solutions depending on the polarity of the large-scale poloidal magnetic field B{sub 0} threading the disk. When B{sub 0}??>0, the horizontal magnetic field is strongly amplified toward the disk interior, leading to a stronger disk wind (by ?50% or less in terms of the wind-driven accretion rate). The enhanced horizontal field also leads to much stronger large-scale Maxwell stress (magnetic braking) that contributes to a considerable fraction of the wind-driven accretion rate. When B{sub 0}??<0, the horizontal magnetic field is reduced, leading to a weaker disk wind (by ? 20%) and negligible magnetic braking. Under fiducial parameters, we find that when B{sub 0}??>0, the laminar region extends farther to ?10-15 AU before the magnetorotational instability sets in, while for B{sub 0}??<0, the laminar region extends only to ?3-5 AU for a typical accretion rate of ?10{sup –8} to10{sup –7} M {sub ?} yr{sup –1}. Scaling relations for the wind properties, especially the wind-driven accretion rate, are provided for aligned and anti-aligned field geometries.
Fractional Quantum Hall Effect and M-Theory
Vafa, Cumrun
2015-01-01
We propose a unifying model for FQHE which on the one hand connects it to recent developments in string theory and on the other hand leads to new predictions for the principal series of experimentally observed FQH systems with filling fraction $\
Fractional Quantum Hall Effect and M-Theory
Cumrun Vafa
2015-11-12
We propose a unifying model for FQHE which on the one hand connects it to recent developments in string theory and on the other hand leads to new predictions for the principal series of experimentally observed FQH systems with filling fraction $\
Magnetic Topological Insulator and Quantum Anomalous Hall Effect
Kou, Xufeng
2015-01-01
M. L. Roukes, et al. , Spintronics: A spin-based electronicsand D. M. Treger, Spintronics - A retrospective andand A. Chtchelkanova, Spintronics: The future of data
Sandia Energy - Second Generation Fractional Quantum Hall Effect
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PREPRINT QUASIPARTICLE AGGREGATION I N THE FRACTIONAL QUANTUM HALL EFFECT
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Robert B. Laughlin and the Fractional Quantum Hall Effect
Office of Scientific and Technical Information (OSTI)
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Quantum chaos and effective thermalization
Altland, Alexander
2011-01-01
We demonstrate effective equilibration for unitary quantum dynamics under conditions of classical chaos. Focusing on the paradigmatic example of the Dicke model, we show how a constructive description of the thermalization process is facilitated by the Glauber $Q$ or Husimi function, for which the evolution equation turns out to be of Fokker-Planck type. The equation describes a competition of classical drift and quantum diffusion in contractive and expansive directions. By this mechanism the system follows a 'quantum smoothened' approach to equilibrium, which avoids the notorious singularities inherent to classical chaotic flows.
Shakouri, Kh.; Peeters, F. M. [Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); Vasilopoulos, P.; Vargiamidis, V. [Department of Physics, Concordia University, 7141 Sherbrooke Ouest Montréal, Québec H4B 1R6 (Canada); Hai, G.-Q. [Instituto de Fisica de São Carlos, Universidade de São Paulo, São Carlos, SP 13560-970 (Brazil)
2014-05-26
We study the commensurability oscillations in silicene subject to a perpendicular electric field E{sub z}, a weak magnetic field B, and a weak periodic potential V=V{sub 0}cos(Cy),C=2?/a{sub 0} with a{sub 0} its period. The field E{sub z} and/or the modulation lift the spin degeneracy of the Landau levels and lead to spin and valley resolved Weiss oscillations. The spin resolution is maximal when the field E{sub z} is replaced by a periodic one E{sub z}=E{sub 0}cos(Dy),D=2?/b{sub 0}, while the valley one is maximal for b{sub 0}?=?a{sub 0}. In certain ranges of B values, the current is fully spin or valley polarized. Additional quantum Hall conductivity plateaux arise due to spin and valley intra-Landau-level transitions.
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)
2014-02-03
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.
Quantum effects near future singularities
John D. Barrow; Antonio B. Batista; Giuseppe Dito; Julio C. Fabris; M. J. S. Houndjo
2012-01-09
General relativity allows a variety of future singularities to occur in the evolution of the universe. At these future singularities, the universe will end in a singular state after a finite proper time and geometrical invariants of the space time will diverge. One question that naturally arises with respect to these cosmological scenarios is the following: can quantum effects lead to the avoidance of these future singularities? We analyze this problem considering massless and conformally coupled scalar fields in an isotropic and homogeneous background leading to future singularities. It is shown that near strong, big rip-type singularities, with violation of the energy conditions, the quantum effects are very important, while near some milder classes of singularity like the sudden singularity, which preserve the energy conditions, quantum effects are irrelevant.
Effective Field Theory of Fractional Quantized Hall Nematics (Journal
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Efimov effect in quantum magnets
Yusuke Nishida; Yasuyuki Kato; Cristian D. Batista
2013-08-23
Physics is said to be universal when it emerges regardless of the underlying microscopic details. A prominent example is the Efimov effect, which predicts the emergence of an infinite tower of three-body bound states obeying discrete scale invariance when the particles interact resonantly. Because of its universality and peculiarity, the Efimov effect has been the subject of extensive research in chemical, atomic, nuclear and particle physics for decades. Here we employ an anisotropic Heisenberg model to show that collective excitations in quantum magnets (magnons) also exhibit the Efimov effect. We locate anisotropy-induced two-magnon resonances, compute binding energies of three magnons and find that they fit into the universal scaling law. We propose several approaches to experimentally realize the Efimov effect in quantum magnets, where the emergent Efimov states of magnons can be observed with commonly used spectroscopic measurements. Our study thus opens up new avenues for universal few-body physics in condensed matter systems.
Quantum Shock Waves - the case for non-linear effects in dynamics of electronic liquids
Eldad Bettelheim; Alexander G. Abanov; Paul Wiegmann
2006-06-29
Using the Calogero model as an example, we show that the transport in interacting non-dissipative electronic systems is essentially non-linear. Non-linear effects are due to the curvature of the electronic spectrum near the Fermi energy. As is typical for non-linear systems, propagating wave packets are unstable. At finite time shock wave singularities develop, the wave packet collapses, and oscillatory features arise. They evolve into regularly structured localized pulses carrying a fractionally quantized charge - {\\it soliton trains}. We briefly discuss perspectives of observation of Quantum Shock Waves in edge states of Fractional Quantum Hall Effect and a direct measurement of the fractional charge.
Beta (?) tungsten thin films: Structure, electron transport, and giant spin Hall effect
Hao, Qiang; Chen, Wenzhe; Xiao, Gang
2015-05-04
We use a simple magnetron sputtering process to fabricate beta (?) tungsten thin films, which are capable of generating giant spin Hall effect. As-deposited thin films are always in the metastable ?-W phase from 3.0 to 26.7?nm. The ?-W phase remains intact below a critical thickness of 22.1?nm even after magnetic thermal annealing at 280?°C, which is required to induce perpendicular magnetic anisotropy (PMA) in a layered structure of ?-W/Co{sub 40}Fe{sub 40}B{sub 20}/MgO. Intensive annealing transforms the thicker films (>22.1?nm) into the stable ?-W phase. We analyze the structure and grain size of both ?- and ?-W thin films. Electron transport in terms of resistivity and normal Hall effect is studied over a broad temperature range of 10?K to at least 300?K on all samples. Very low switching current densities are achieved in ?-W/Co{sub 40}Fe{sub 40}B{sub 20}/MgO with PMA. These basic properties reveal useful behaviors in ?-W thin films, making them technologically promising for spintronic magnetic random access memories and spin-logic devices.
Temperature-driven band inversion in Pb?.??Sn?.??Se: Optical and Hall-effect studies
Anand, Naween; Gu, Genda; Buvaev, Sanal; Hebard, A. F.; Tanner, D. B.; Chen, Zhiguo; Li, Zhiqiang; Choudhary, Kamal; Sinnott, S. B.; Martin, C.
2014-12-23
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.
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.
2014-12-23
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
2014-05-07
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
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
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)
2014-12-01
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.
Interface effect in coupled quantum wells
Hao, Ya-Fei
2014-06-28
This paper intends to theoretically investigate the effect of the interfaces on the Rashba spin splitting of two coupled quantum wells. The results show that the interface related Rashba spin splitting of the two coupled quantum wells is both smaller than that of a step quantum well which has the same structure with the step quantum well in the coupled quantum wells. And the influence of the cubic Dresselhaus spin-orbit interaction of the coupled quantum wells is larger than that of a step quantum well. It demonstrates that the spin relaxation time of the two coupled quantum wells will be shorter than that of a step quantum well. As for the application in the spintronic devices, a step quantum well may be better than the coupled quantum wells, which is mentioned in this paper.
Skinner, T. D.; Olejnik, K.; Cunningham, L. K.; Kurebayashi, H.; Campion, R. P.; Gallagher, B. L.; Jungwirth, T.; Ferguson, A. J.
2015-03-31
spin Hall effect3 (SHE) is absorbed in the ferromagnet and induces the spin transfer torque4 (STT). In the other pic- ture, a non-equilibrium spin-density is generated via the relativistic inverse spin galvanic effect5 (ISGE) and induces the spin...
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)
2010-07-15
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.
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)
2014-02-15
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
2008-03-25
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.
Dynamical Scaling of the Quantum Hall Plateau Transition F. Hohls,1,* U. Zeitler,1
Hohls, Frank
, they occur only at zero temperature [1]. However, as long as the quantum fluctuations governing transitions occur at a critical value of a parameter which can be, e.g., the disorder in the metal system is the distance from a critical energy Ec which can be identified as the center of a disorder
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)
2011-01-15
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.
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Comparison of quantum confinement effects between quantum wires and dots
Li, Jingbo; Wang, Lin-Wang
2004-03-30
Dimensionality is an important factor to govern the electronic structures of semiconductor nanocrystals. The quantum confinement energies in one-dimensional quantum wires and zero-dimensional quantum dots are quite different. Using large-scale first-principles calculations, we systematically study the electronic structures of semiconductor (including group IV, III-V, and II-VI) surface-passivated quantum wires and dots. The band-gap energies of quantum wires and dots have the same scaling with diameter for a given material. The ratio of band-gap-increases between quantum wires and dots is material-dependent, and slightly deviates from 0.586 predicted by effective-mass approximation. Highly linear polarization of photoluminescence in quantum wires is found. The degree of polarization decreases with the increasing temperature and size.
Extrinsic anomalous Hall effect in epitaxial Mn{sub 4}N films
Meng, M.; Wu, S. X. Ren, L. Z.; Zhou, W. Q.; Wang, Y. J.; Wang, G. L.; Li, S. W.
2015-01-19
Anomalous Hall effect (AHE) in ferrimagnetic Mn{sub 4}N epitaxial films grown by molecular-beam epitaxy is investigated. The longitudinal conductivity ?{sub xx} is within the superclean regime, indicating Mn{sub 4}N is a highly conducting material. We further demonstrate that the AHE signal in 40-nm-thick films is mainly due to the extrinsic contributions based on the analysis fitted by ?{sub AH}=a??{sub xx0}+b?{sub xx}{sup 2} and ?{sub AH}??{sub xx}. Our study not only provide a strategy for further theoretical work on antiperovskite manganese nitrides but also shed promising light on utilizing their extrinsic AHE to fabricate spintronic devices.
PIC simulation of SPT Hall thrusters : high power operation and wall effects
Sullivan, Kay Ueda, 1980-
2004-01-01
The fully kinetic Hall Thruster simulation built by [1] and used by [2] is further refined and used to obtain results for the P5 SPT Hall thruster at 3kw and 5kw operation. Performance data agree well with experiments [3], ...
Maxwell-Garnett effective medium theory: Quantum nonlocal effects
Moradi, Afshin
2015-04-15
We develop the Maxwell-Garnett theory for the effective medium approximation of composite materials with metallic nanoparticles by taking into account the quantum spatial dispersion effects in dielectric response of nanoparticles. We derive a quantum nonlocal generalization of the standard Maxwell-Garnett formula, by means the linearized quantum hydrodynamic theory in conjunction with the Poisson equation as well as the appropriate additional quantum boundary conditions.
Quantum Field Theory in Graphene
I. V. Fialkovsky; D. V. Vassilevich
2011-11-18
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.
Formation of quantum spin Hall state on Si surface and energy gap scaling with
Simons, Jack
on a semiconductor surface, based on first-principles calculations and effective Hamiltonian analysis. We show is to directly fabricate large-gap TIs on semiconductor surfaces, which may avoid problems like transfer . Recent studies pertaining to Bi/Sb(111) films1417 , Sn films18 , metal-decorated graphene19
Parallelization of particle-in-cell simulation modeling Hall-effect thrusters
Fox, Justin M., 1981-
2005-01-01
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 ...
"Exotic" quantum effects in the laboratory?
Ralf Schützhold
2010-04-15
This Article provides a brief (non-exhaustive) review of some recent developments regarding the theoretical and possibly experimental study of "exotic" quantum effects in the laboratory with special emphasis on cosmological particle creation, Hawking radiation, and the Unruh effect.
Hankiewicz, EM; Li, J.; Jungwirth, T.; Niu, Q.; Shen, SQ; Sinova, Jairo.
2005-01-01
We study theoretically the spin-Hall effect as well as its reciprocal phenomenon (a transverse charge current driven by a spin-dependent chemical potential gradient) in electron and hole finite size mesoscopic systems. The Landauer...
Understanding the physics of a possible non-Abelian fractional quantum hall
Office of Scientific and Technical Information (OSTI)
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Understanding the physics of a possible non-Abelian fractional quantum hall
Office of Scientific and Technical Information (OSTI)
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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail.Theory of rare Kaon and(Conference)Connecteffect state. (Technical Report)
Ozturk, Salih Baris
2007-04-25
3.2 Principles of Self-Commisioning with Identification ..............................68 3.3 Resistance and dq-axis Synchronous Inductance Measurements.............69 3.4 Measurment of the Back-EMF Constant and Rotor Flux Linkage ..........79 3... represented as ..........................26 r 2.3. Q-axis leading d-axis and the rotor angle represented as ? ...........................28 2.4. Line-to-line back-EMF ( ), phase back-EMFs, phase current ab waveforms and hall-effect position...
Large anomalous Hall effect in ferromagnetic insulator-topological insulator heterostructures
Alegria, L. D.; Petta, J. R.; Ji, H.; Cava, R. J.; Yao, N.; Clarke, J. J.
2014-08-04
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.
Jefferson Lab Experimental Hall D
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Information Hall D General Information Hall D Meetings Calendar (Regina) Hall D Civil - selected drawings (pdf) Hall D Basic Equipment Description on Hall D Wiki JLab Experimental...
Effects of Hall current and electron temperature anisotropy on proton fire-hose instabilities
Hau, L.-N. [Institute of Space Science, National Central University, Jhongli, Taiwan (China) [Institute of Space Science, National Central University, Jhongli, Taiwan (China); Department of Physics, National Central University, Jhongli, Taiwan (China); Wang, B.-J. [Institute of Space Science, National Central University, Jhongli, Taiwan (China) [Institute of Space Science, National Central University, Jhongli, Taiwan (China); Institute of Astronomy, National Central University, Jhongli, Taiwan (China)
2013-10-15
The standard magnetohydrodynamic (MHD) theory predicts that the Alfvén wave may become fire-hose unstable for ?{sub ?}??{sub ?}>2. In this study, we examine the proton fire-hose instability (FHI) based on the gyrotropic two-fluid model, which incorporates the ion inertial effects arising from the Hall current and electron temperature anisotropy but neglects the electron inertia in the generalized Ohm's law. The linear dispersion relation is derived and analyzed which in the long wavelength approximation, ?{sub i}k?0 or ?{sub e}=?{sub 0}(p{sub ?,e}?p{sub ?,e})/B{sup 2}=1, recovers the ideal MHD model with separate temperature for ions and electrons. Here, ?{sub i} is the ion inertial length and k is the wave number. For parallel propagation, both ion cyclotron and whistler waves become propagating and growing for ?{sub ?}??{sub ?}>2+?{sub i}{sup 2}k{sup 2}(?{sub e}?1){sup 2}/2. For oblique propagation, the necessary condition for FHI remains to be ?{sub ?}??{sub ?}>2 and there exist one or two unstable fire-hose modes, which can be propagating and growing or purely growing. For large ?{sub i}k values, there exists no nearly parallel FHI leaving only oblique FHI and the effect of ?{sub e}>1 may greatly enhance the growth rate of parallel and oblique FHI. The magnetic field polarization of FHI may be reversed due to the sign change associated with (?{sub e}?1) and the purely growing FHI may possess linear polarization while the propagating and growing FHI may possess right-handed or left-handed polarization.
Hohls, Frank
VOLUME 86, NUMBER 22 P H Y S I C A L R E V I E W L E T T E R S 28 MAY 2001 High Frequency the complex conductivity sxx of a two-dimensional electron system in the quantum Hall regime up to frequencies can be scaled to a single function for different frequencies and several tran- sitions between
Prestgard, Megan C.; Tiwari, Ashutosh
2014-03-24
The inverse spin Hall effect (ISHE) is a newly discovered, quantum mechanical phenomenon where an applied spin current results in the generation of an electrical voltage in the transverse direction. It is anticipated that the ISHE can provide a more simple way of measuring spin currents in spintronic devices. The ISHE was first observed in noble metals that exhibit strong spin-orbit coupling. However, recently, the ISHE has been detected in conventional semiconductors (such as Si and Ge), which possess weak spin-orbit coupling. This suggests that large-spin orbit coupling is not a requirement for observing the ISHE. In this paper, we are reporting the observation of the ISHE in an alternative semiconductor material, zinc oxide (ZnO) using all-electrical means. In our study, we found that when a spin-polarized current is injected into the ZnO film from a NiFe ferromagnetic injector via an MgO tunnel barrier layer, a voltage transverse to both the direction of the current as well as its spin-polarization is generated in the ZnO layer. The polarity of this voltage signal was found to flip on reversing the direction of the injected current as well as on reversing the polarization of the current, consistent with the predictions of the ISHE process. Through careful analysis of the ISHE data, we determined a spin-Hall angle of approximately 1.651 × 10{sup ?2} for ZnO, which is two orders of magnitude higher than that of silicon. Observation of a detectable room-temperature ISHE signal in ZnO via electrical injection and detection is a groundbreaking step that opens a path towards achieving transparent spin detectors for next-generation spintronic device technology.
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, ...
WIGNER MOLECULES IN SEMICONDUCTOR QUANTUM DOTS AND TRAPPED ULTRACOLD BOSONIC CLOUDS
Yannouleas, Constantine
WIGNER MOLECULES IN SEMICONDUCTOR QUANTUM DOTS AND TRAPPED ULTRACOLD BOSONIC CLOUDS Constantine], with a focus on the strongly correlated regime of electrons in two-dimensional semiconductor quantum dots (QDs dot [3]; (3) fractional-quantum-Hall-effect analogies and differences in graphene quantum dots at zero
Gong, Zhirui; Liu, G. B.; Yu, Hongyi; Xiao, Di; Cui, Xiaodong; Xu, Xiaodong; Yao, Wang
2013-01-01
In monolayer group-VI transition metal dichalcogenides, charge carriers have spin and valley degrees of freedom, both associated with magnetic moments. On the other hand, the layer degree of freedom in multilayers is associated with electrical polarization. Here we show that transition metal dichalcogenide bilayers offer an unprecedented platform to realize a strong coupling between the spin, valley and layer pseudospin of holes. Such coupling gives rise to the spin Hall effect and spin-dependent selection rule for optical transitions in inversion symmetric bilayer and leads to a variety of magnetoelectric effects permitting quantum manipulation of these electronic degrees of freedom. Oscillating electric and magnetic fields can both drive the hole spin resonance where the two fields have valley-dependent interference, making an interplay between the spin and valley as information carriers possible for potential valley-spintronic applications. We show how to realize quantum gates on the spin qubit controlled by the valley bit.
Building Abbreviations Alumni Hall
Johnson Jr.,, Ray
20A/B 44 20A/B 44 20A/B 44 58 17 17 88 34 25 Building Abbreviations Alumni Hall Campbell Dome Colden FitzGerald Gym Frese Hall G Building Gertz Center Goldstein Theatre Honors Hall GC GB GT HH MU KY KG KS KP PH I Building Jefferson Hall Kiely Hall King Hall Kissena Hall Klapper Hall Music Building
On the Rôle of a Torsion-like Field in a Scenario for the Spin Hall Effect
C. F. L. Godinho; J. A. Helayël Neto
2014-12-13
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.
Temperature dependence of the photo-induced inverse spin Hall effect in Au/InP hybrid structures
Khamari, Shailesh K. Porwal, S.; Dixit, V. K.; Sharma, T. K.
2014-01-27
Photo-induced Inverse Spin Hall Effect (ISHE) measurements on Au/InP hybrid structures are performed over a temperature range of 45 to 300?K. Dependence of the spin current density on the degree of circular polarization and also on the angle of incidence of laser beam confirms the ISHE origin of measured signal. The magnitude of ISHE increases with sample cooling. A numerical model based on the spin relaxation of non-equilibrium spin-polarized electrons is proposed for predicting the temperature dependence of ISHE. Our results indicate that the proposed device can be used as a spin photodetector over a wide temperature range.
Nonlinear effect on quantum control for two-level systems
W. Wang; J. Shen; X. X. Yi
2009-06-05
The traditional quantum control theory focuses on linear quantum system. Here we show the effect of nonlinearity on quantum control of a two-level system, we find that the nonlinearity can change the controllability of quantum system. Furthermore, we demonstrate that the Lyapunov control can be used to overcome this uncontrollability induced by the nonlinear effect.
Temperature-driven band inversion in Pb0.77Sn0.23Se: Optical and Hall effect studies
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Anand, Naween; Buvaev, Sanal; Hebard, A. F.; Tanner, D. B.; Chen, Zhiguo; Li, Zhiqiang; Choudhary, Kamal; Sinnott, S. B.; Gu, Genda; Martin, C.
2014-12-23
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. Thus, density function theory calculation for the electronic band structure also make similar predictions.« less
Shepelyansky, Dima
as an electromotive force (EMF), to develop across the system. In semicon- ductors, such a photovoltaic effect canarXiv:1101.5667v1[cond-mat.mes-hall]29Jan2011 Resonant Photovoltaic Effect in Surface into electricity and has important appli- cations in photodiodes and photovoltaic cells. Recently, significant
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
Significant Quantum Effects in Hydrogen Activation
Kyriakou, Georgios; Davidson, Erlend R.; Peng, Guowen; Roling, Luke T.; Singh, Suyash; Boucher, Matthew B.; Marcinkowski, Matthew D.; Mavrikakis, Manos; Michaelides, Angelos; Sykes, E. Charles H.
2014-05-27
Dissociation of molecular hydrogen is an important step in a wide variety of chemical, biological, and physical processes. Due to the light mass of hydrogen, it is recognized that quantum effects are often important to its reactivity. However, understanding how quantum effects impact the reactivity of hydrogen is still in its infancy. Here, we examine this issue using a well-defined Pd/Cu(111) alloy that allows the activation of hydrogen and deuterium molecules to be examined at individual Pd atom surface sites over a wide range of temperatures. Experiments comparing the uptake of hydrogen and deuterium as a function of temperature reveal completely different behavior of the two species. The rate of hydrogen activation increases at lower sample temperature, whereas deuterium activation slows as the temperature is lowered. Density functional theory simulations in which quantum nuclear effects are accounted for reveal that tunneling through the dissociation barrier is prevalent for H2 up to 190 K and for D2 up to 140 K. Kinetic Monte Carlo simulations indicate that the effective barrier to H2 dissociation is so low that hydrogen uptake on the surface is limited merely by thermodynamics, whereas the D2 dissociation process is controlled by kinetics. These data illustrate the complexity and inherent quantum nature of this ubiquitous and seemingly simple chemical process. Examining these effects in other systems with a similar range of approaches may uncover temperature regimes where quantum effects can be harnessed, yielding greater control of bond-breaking processes at surfaces and uncovering useful chemistries such as selective bond activation or isotope separation.
Quantum Mechanical Effects in Gravitational Collapse
Eric Greenwood
2010-01-12
In this thesis we investigate quantum mechanical effects to various aspects of gravitational collapse. These quantum mechanical effects are implemented in the context of the Functional Schr\\"odinger formalism. The Functional Schr\\"odinger formalism allows us to investigate the time-dependent evolutions of the quantum mechanical effects, which is beyond the scope of the usual methods used to investigate the quantum mechanical corrections of gravitational collapse. Utilizing the time-dependent nature of the Functional Schr\\"odinger formalism, we study the quantization of a spherically symmetric domain wall from the view point of an asymptotic and infalling observer, in the absence of radiation. To build a more realistic picture, we then study the time-dependent nature of the induced radiation during the collapse using a semi-classical approach. Using the domain wall and the induced radiation, we then study the time-dependent evolution of the entropy of the domain wall. Finally we make some remarks about the possible inclusion of backreaction into the system.
Dependence of the intrinsic spin-Hall effect on spin-orbit interaction character RID B-5617-2009
Nomura, K.; Sinova, Jairo; Sinitsyn, NA; MacDonald, AH.
2005-01-01
We report on a comparative numerical study of the spin-Hall conductivity in two dimensions for three different spin-orbit interaction models
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
Spin Hall magnetoresistance at Pt/CoFe{sub 2}O{sub 4} interfaces and texture effects
Isasa, Miren; Bedoya-Pinto, Amilcar; Vélez, Saül; Golmar, Federico; Sánchez, Florencio; Fontcuberta, Josep; Hueso, Luis E.; Casanova, Fèlix
2014-10-06
We report magnetoresistance measurements on thin Pt bars grown on epitaxial (001) and (111) CoFe{sub 2}O{sub 4} (CFO) ferrimagnetic insulating films. The results can be described in terms of the recently discovered spin Hall magnetoresistance (SMR). The magnitude of the SMR depends on the interface preparation conditions, being optimal when the Pt/CFO samples are prepared in situ, in a single process. The spin-mixing interface conductance, the key parameter governing SMR and other relevant spin-dependent phenomena, such as spin pumping or spin Seebeck effect, is found to be different depending on the crystallographic orientation of CFO, highlighting the role of the composition and density of magnetic ions at the interface on spin mixing.
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)
2009-10-15
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.
Effect of local filtering on Freezing Phenomena of Quantum Correlation
Sumana Karmakar; Ajoy Sen; Amit Bhar; Debasis Sarkar
2015-04-20
General quantum correlations measures like quantum discord, one norm geometric quantum discord, exhibit freezing, sudden change, double sudden change behavior in their decay rates under different noisy channels. Therefore, one may attempt to investigate how the freezing behavior and other dynamical features are affected under application of local quantum operations. In this work, we demonstrate the effect of local filtering on the dynamical evolution of quantum correlations. We have found that using local filtering one may remove freezing depending upon the filtering parameter.
Quantum gravity effects in the Kerr spacetime
Reuter, M.; Tuiran, E.
2011-02-15
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.
Quantum nonlocal effects on optical properties of spherical nanoparticles
Moradi, Afshin
2015-02-15
To study the scattering of electromagnetic radiation by a spherical metallic nanoparticle with quantum spatial dispersion, we develop the standard nonlocal Mie theory by allowing for the excitation of the quantum longitudinal plasmon modes. To describe the quantum nonlocal effects, we use the quantum longitudinal dielectric function of the system. As in the standard Mie theory, the electromagnetic fields are expanded in terms of spherical vector wavefunctions. Then, the usual Maxwell boundary conditions are imposed plus the appropriate additional boundary conditions. Examples of calculated extinction spectra are presented, and it is found that the frequencies of the subsidiary peaks, due to quantum bulk plasmon excitations exhibit strong dependence on the quantum spatial dispersion.
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Kim, Sang-Il; Seo, Min-Su; Park, Seung-Young; Kim, Dong-Jun; Park, Byong-Guk
2015-01-19
Ta-layer thickness (t{sub Ta}) dependence of the measured DC voltage V from the inverse-spin Hall effect (ISHE) in Ta/CoFeB bilayer structure is experimentally investigated using the ferromagnetic resonance in the TE{sub 011} resonant cavity. The ISHE signals excluding the spin-rectified effect (SRE) were separated from the fitted curve of V against t{sub Ta}. For t{sub Ta}????{sub Ta} (Ta-spin diffusion length?=?2.7?nm), the deviation in ISHE voltage V{sub ISH} between the experimental and theoretical values is significantly increased because of the large SRE contribution, which also results in a large deviation in the spin Hall angle ?{sub SH} (from 10% to 40%). However, when t{sub Ta} ? ?{sub Ta}, the V{sub ISH} values are consistent with theoretical values because the SRE terms become negligible, which subsequently improves the accuracy of the obtained ?{sub SH} within 4% deviation. The results will provide an outline for an accurate estimation of the ?{sub SH} for materials with small ? value, which would be useful for utilizing the spin Hall effect in a 3-terminal spintronic devices in which magnetization can be controlled by in-plane current.
Quantum Coherence Effects in Novel Quantum Optical Systems
Sete, Eyob Alebachew
2012-10-19
Optical response of an active medium can substantially be modified when coherent superpositions of states are excited, that is, when systems display quantum coherence and interference. This has led to fascinating applications in atomic and molecular...
2D massless QED Hall half-integer conductivity and graphene
A. Pérez Martínez; E. Rodriguez Querts; H. Pérez Rojas; R. Gaitan; S. Rodriguez Romo
2011-10-13
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.
Dennett, Daniel
Carpenter House 176 Curtis Wilson BlakesleeBlakeslee Sawyer Office Services Hallowell Hall Blakely Elliot-Pearson Child Dev. Centr. Elliot-Pearson Child Dev. Centr. Robinson Hall Hamilton Pool Halligan Hall Paige Hall
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Non-abelian fractional quantum hall effect for fault-resistant...
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(SNL-NM), Albuquerque, NM (United States) Sponsoring Org: USDOE National Nuclear Security Administration (NNSA) Country of Publication: United States Language: English...
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
Fractional Quantum Hall Effect at Landau Level Filling v=4/11. (Journal
Office of Scientific and Technical Information (OSTI)
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Observation of the Integer Quantum Hall Effect in Record High-Mobility
Office of Scientific and Technical Information (OSTI)
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Weightlessness of photons: A quantum effect
Ari Brynjolfsson
2006-02-17
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.
EPR, Bell, Schrodinger's cat, and the Monty Hall Paradox
Doron Cohen
2007-04-09
The purpose of this manuscript is to provide a short pedagogical explanation why "quantum collapse" is not a metaphysical event, by pointing out the analogy with a "classical collapse" which is associated with the Monty Hall Paradox.
The Effects of Quantum Entropy on the Bag Constant
Miller, D E; Miller, David E.; Tawfik, Abdel-Nasser
2003-01-01
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.
Capogna, Luca
2014 - 2015 Residence Hall Handbook #12;2014-2015 RESIDENCE HALL HANDBOOK The policies Shooter Guidelines 38 2.21 Sustainable Living Tips for Residence Hall Students 39 2.22 Campus Commons 40 3 printing, editing and any revisions, additions or deletions during the course of the year easier to manage
Carlos III de Madrid, Universidad
American Institute of Aeronautics and Astronautics 1 Magnetic field effects on secondary electron, CT AIAA 2008-4725 Copyright © 2008 by the authors. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. #12;American Institute of Aeronautics and Astronautics 2 Figure 1. Sketch
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)
2014-11-03
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.
Hall conductance and topological invariant for open systems
H. Z. Shen; W. Wang; X. X. Yi
2014-10-07
The Hall conductivity given by the Kubo formula is a linear response of the quantum transverse transport to a weak electric field. It has been intensively studied for a quantum system without decoherence, but it is barely explored for systems subject to decoherence. In this paper, we develop a formalism to deal with this issue for topological insulators. The Hall conductance for a topological insulator coupled to an environment is derived, the derivation is based on a linear response theory of open system. As an application, the Hall conductance of a two-band topological insulator and a two-dimensional lattice is presented and discussed.
Quantum radiation by electrons in lasers and the Unruh effect
Ralf Schützhold; Clovis Maia
2010-04-14
In addition to the Larmor radiation known from classical electrodynamics, electrons in a laser field may emit pairs of entangled photons -- which is a pure quantum effect. We investigate this quantum effect and discuss why it is suppressed in comparison with the classical Larmor radiation (which is just Thomson backscattering of the laser photons). Further, we provide an intuitive explanation of this process (in a simplified setting) in terms of the Unruh effect.
A study of Quantum Correlation for Three Qubit States under the effect of Quantum Noisy Channels
Pratik K. Sarangi; Indranil Chakrabarty
2014-11-27
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.
Memory effects in quantum channel discrimination
Giulio Chiribella; Giacomo M. D'Ariano; Paolo Perinotti
2008-04-02
We consider quantum-memory assisted protocols for discriminating quantum channels. We show that for optimal discrimination of memory channels, memory assisted protocols are needed. This leads to a new notion of distance for channels with memory. For optimal discrimination and estimation of sets of unitary channels memory-assisted protocols are not required.
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
Monte Carlo simulation of quantum Zeno effect in the brain
Danko Georgiev
2014-12-11
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.
Plasmon modes of metallic nanowires including quantum nonlocal effects
Moradi, Afshin
2015-03-15
The properties of electrostatic surface and bulk plasmon modes of cylindrical metallic nanowires are investigated, using the quantum hydrodynamic theory of plasmon excitation which allows an analytical study of quantum tunneling effects through the Bohm potential term. New dispersion relations are obtained for each type of mode and their differences with previous treatments based on the standard hydrodynamic model are analyzed in detail. Numerical results show by considering the quantum effects, as the value of wave number increases, the surface modes are slightly red-shifted first and then blue-shifted while the bulk modes are blue-shifted.
Quantum Walks With Neutral Atoms: Quantum Interference Effects of One and Two Particles
Robens, Carsten; Meschede, Dieter; Alberti, Andrea
2015-01-01
We report on the state of the art of quantum walk experiments with neutral atoms in state-dependent optical lattices. We demonstrate a novel state-dependent transport technique enabling the control of two spin-selective sublattices in a fully independent fashion. This transport technique allowed us to carry out a test of single-particle quantum interference based on the violation of the Leggett-Garg inequality and, more recently, to probe two-particle quantum interference effects with neutral atoms cooled into the motional ground state. These experiments lay the groundwork for the study of discrete-time quantum walks of strongly interacting, indistinguishable particles to demonstrate quantum cellular automata of neutral atoms.
Low-Energy Effective Theories of Quantum Link and Quantum Spin Models
B. Schlittgen; U. -J. Wiese
2000-12-11
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.
J. E. Avron; A. Elgart; G. M. Graf; L. Sadun
2001-07-12
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.
Noble, James S.
PAVILION JOHNSTON GILLETT LATHROP SOUTH HALL LAWS CONLEY AVE PARKING GARAGE UNIVERSITY AVE PARKING GARAGE QUARRY CENTER HEARNES MULTIPURPOSE BUILDING LOCUST STREET BUILDING REYNOLDS ALUMNI CENTER LEWIS DALTON
Experimental Hall D | Jefferson Lab
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
top-right bottom-left-corner bottom-right-corner Experimental Hall D Jefferson Lab's fourth experimental hall, known as Hall D, began receiving beam for calibration and...
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
2014-11-13
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.
Unknown
2009-01-01
Measurements of the Hall coefficient and resistivity for highly oriented Tl2Ba2CaCu2O8+delta thin films are reported. The temperature dependence of cotTHETA(H), where THETA(H) is the normal-state Hall angle, for a single-phase (2:2:1:2) film sample...
An Equation of Motion with Quantum Effect in Spacetime
Jyh-Yang Wu
2009-05-26
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.
Polymer quantum effects on compact stars models
Guillermo Chacon-Acosta; Hector Hernandez-Hernandez
2014-08-05
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$.
Stephen F. & Camilla T. Brauer Hall & Preston M. Green Hall
Subramanian, Venkat
Preston M. Green Hall was completed in August of 2011. Washington University has adopted a holistic1 Stephen F. & Camilla T. Brauer Hall & Preston M. Green Hall: LEED® Building Tour To Our Visitors & Guests: Stephen F. & Camilla T. Brauer Hall was completed in April 2010, while
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 ğJ ¼ 0Ş 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
2005-05-31
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.
Dalton, Mark M.
2014-02-01
Report over the experimental activities in Hall A at Thomas Jefferson National Accelerator Facility during 2013.
M. M. Dalton; K. Allada; K. Aniol; W. Boeglin; A. Camsonne; E. Chudakov; M. Cummings; D. Flay; M. Friedman; O. Glamazdin; J. Gomez; C. Keppel; H. P. Khanal; R. Lindgren; E. Long; R. Michaels; M. Mihovilovi?; C. Muñoz Camacho; S. Nanda; R. Pomatsalyuk; S. Riordan; S. Širca; C. Smith; P. Solvignon; N. F. Sparveris; V. Vereshchaka; X. Yan; Z. Ye; Y. X. Zhao; Jefferson Lab Hall A Collaboration
2014-02-27
Report over the experimental activities in Hall A at Thomas Jefferson National Accelerator Facility during 2013.
Energy spectrum, dissipation, and spatial structures in reduced Hall magnetohydrodynamic
Martin, L. N.; Dmitruk, P.; Gomez, D. O.
2012-05-15
We analyze the effect of the Hall term in the magnetohydrodynamic turbulence under a strong externally supported magnetic field, seeing how this changes the energy cascade, the characteristic scales of the flow, and the dynamics of global magnitudes, with particular interest in the dissipation. Numerical simulations of freely evolving three-dimensional reduced magnetohydrodynamics are performed, for different values of the Hall parameter (the ratio of the ion skin depth to the macroscopic scale of the turbulence) controlling the impact of the Hall term. The Hall effect modifies the transfer of energy across scales, slowing down the transfer of energy from the large scales up to the Hall scale (ion skin depth) and carrying faster the energy from the Hall scale to smaller scales. The final outcome is an effective shift of the dissipation scale to larger scales but also a development of smaller scales. Current sheets (fundamental structures for energy dissipation) are affected in two ways by increasing the Hall effect, with a widening but at the same time generating an internal structure within them. In the case where the Hall term is sufficiently intense, the current sheet is fully delocalized. The effect appears to reduce impulsive effects in the flow, making it less intermittent.
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."
QUANTUM EFFECTS IN ROTATIONAL RELAXATION OF A FREELY EXPANDING GAS
Riabov, Vladimir V.
QUANTUM EFFECTS IN ROTATIONAL RELAXATION OF A FREELY EXPANDING GAS I. V. Lebed' and V. V. Ryabov of freedom is dis- turbed in expansion of a molecular gas into a vacuum [1, 2]. Departure of the rotational energy oil the gas from the equilibrium for a given kinetic temperature results from a sharp drop
Quantum Gravity Effect in Torsion Driven Inflation and CP violation
Sayantan Choudhury; Barun Kumar Pal; Banasri Basu; Pratul Bandyopadhyay
2015-10-10
We have derived an effective potential for inflationary scenario from torsion and quantum gravity correction in terms of the scalar field hidden in torsion. A strict bound on the CP violating $\\theta$ parameter, ${\\cal O}(10^{-10})<\\theta<{\\cal O}(10^{-9})$ has been obtained, using {\\tt Planck+WMAP9} best fit cosmological parameters.
Tunneling in Polymer Quantization and the Quantum Zeno Effect
Durmus Ali Demir; Ozan Sargin
2014-09-25
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.
Lecture Notes in Quantum Mechanics
Doron Cohen
2013-08-27
These lecture notes cover undergraduate textbook topics (e.g. as in Sakurai), and also additional advanced topics at the same level of presentation. In particular: EPR and Bell; Basic postulates; The probability matrix; Measurement theory; Entanglement; Quantum computation; Wigner-Weyl formalism; The adiabatic picture; Berry phase; Linear response theory; Kubo formula; Modern approach to scattering theory with mesoscopic orientation; Theory of the resolvent and the Green function; Gauge and Galilei Symmetries; Motion in magnetic field; Quantum Hall effect; Quantization of the electromagnetic field; Fock space formalism.
Fractal sets of dual topological quantum numbers
Wellington da Cruz
2004-06-18
The universality classes of the quantum Hall transitions are considered in terms of fractal sets of dual topological quantum numbers filling factors, labelled by a fractal or Hausdorff dimension defined into the interval $1 < h < 2$ and associated with fractal curves. We show that our approach to the fractional quantum Hall effect-FQHE is free of any empirical formula and this characteristic appears as a crucial insight for our understanding of the FQHE. According to our formulation, the FQHE gets a fractal structure from the connection between the filling factors and the Hausdoff dimension of the quantum paths of particles termed fractons which obey a fractal distribution function associated with a fractal von Neumann entropy. This way, the quantum Hall transitions satisfy some properties related to the Farey sequences of rational numbers and so our theoretical description of the FQHE establishes a connection between physics, fractal geometry and number theory. The FQHE as a convenient physical system for a possible prove of the Riemann hypothesis is suggested.
Hall viscosity from elastic gauge fields in Dirac crystals
Alberto Cortijo; Yago Ferreirós; Karl Landsteiner; María A. H. Vozmediano
2015-06-16
The combination of Dirac physics and elasticity has been explored at length in graphene where the so--called "elastic gauge fields" have given rise to an entire new field of research and applications: Straintronics. The fact that these elastic fields couple to fermions as the electromagnetic field, implies that many electromagnetic responses will have elastic counterparts not explored before. In this work we will first show that the presence of elastic gauge fields will be the rule rather than the exception in most of the topologically non--trivial materials in two and three dimensions. In particular we will extract the elastic gauge fields associated to the recently observed Weyl semimetals, the "three dimensional graphene". As it is known, quantum electrodynamics suffers from the chiral anomaly whose consequences have been recently explored in matter systems. We will show that, associated to the physics of the anomalies, and as a counterpart of the Hall conductivity, elastic materials will have a Hall viscosity in two and three dimensions with a coefficient orders of magnitude bigger than the previously studied response. The magnitude and generality of the new effect will greatly improve the chances for the experimental observation of this topological, non dissipative response.
arXiv:0802.2364v2[cond-mat.mes-hall]5Jun2008 Quantum Stirring in low dimensional devices
Cohen, Doron
in Ref.1 . The scat- terer is a potential barrier whose location x = X1 and transmission gX = g(X2 original size. Quantum stirring4,5 is the operation of inducing a DC circulating current by means of ACV is the transmission of the ring segment that does not include the moving scatterer, as defined by its Landauer
Anti-Zeno Effect for Quantum Transport in Disordered Systems
Keisuke Fujii; Katsuji Yamamoto
2010-10-21
We demonstrate that repeated measurements in disordered systems can induce quantum anti-Zeno effect under certain condition to enhance quantum transport. The enhancement of energy transfer is really exhibited with a simple model under repeated measurements. The optimal measurement interval for the anti-Zeno effect and the maximal efficiency of energy transfer are specified in terms of the relevant physical parameters. Since the environment acts as frequent measurements on the system, the decoherence-induced energy transfer, which has been discussed recently for photosynthetic complexes, may be interpreted in terms of the anti-Zeno effect. We further find an interesting phenomenon, where local decoherence or repeated measurements may even promote entanglement generation between the non-local sites.
Secular effects on inflation from one-loop quantum gravity
J. A. Cabrer; D. Espriu
2007-10-03
In this paper we revisit and extend a previous analysis where the possible relevance of quantum gravity effects in a cosmological setup was studied. The object of interest are non-local (logarithmic) terms generated in the effective action of gravity due to the exchange in loops of massless modes (such as photons or the gravitons themselves). We correct one mistake existing in the previous work and discuss the issue in a more general setting in different cosmological scenarios. We obtain the one-loop quantum-corrected evolution equations for the cosmological scale factor up to a given order in a derivative expansion in two particular cases: a matter dominated universe with vanishing cosmological constant, and in a de Sitter universe. We show that the quantum corrections, albeit tiny, may have a secular effect that eventually modifies the expansion rate. For a de Sitter universe they tend to slow down the rate of the expansion, while the effect seems to have the opposite sign in a matter dominated universe. To partly understand these effects we provide a complementary newtonian analysis.
Non-adiabatic effect on the quantum heat flux control
Chikako Uchiyama
2014-05-08
We provide a general formula of quantum transfer that includes the non-adiabatic effect under periodic environmental modulation by using full counting statistics in Hilbert-Schmidt space. Applying the formula to an anharmonic junction model that interacts with two bosonic environments within the Markovian approximation, we find that the quantum transfer is divided into the adiabatic (dynamical and geometrical phases) and non-adiabatic contributions. This extension shows the dependence of quantum transfer on the initial condition of the anharmonic junction just before the modulation, as well as the characteristic environmental parameters such as interaction strength and cut-off frequency of spectral density. We show that the non-adiabatic contribution represents the reminiscent effect of past modulation including the transition from the initial condition of the anharmonic junction to a steady state determined by the very beginning of the modulation. This enables us to tune the frequency range of modulation, whereby we can obtain the quantum flux corresponding to the geometrical phase by setting the initial condition of the anharmonic junction.
Nambu-Goldstone Effective Theory of Information at Quantum Criticality
Gia Dvali; Andre Franca; Cesar Gomez; Nico Wintergerst
2015-07-10
We establish a fundamental connection between quantum criticality of a many-body system, such as Bose-Einstein condensates, and its capacity of information-storage and processing. For deriving the effective theory of modes in the vicinity of the quantum critical point we develop a new method by mapping a Bose-Einstein condensate of $N$-particles onto a sigma model with a continuous global (pseudo)symmetry that mixes bosons of different momenta. The Bogolyubov modes of the condensate are mapped onto the Goldstone modes of the sigma model, which become gapless at the critical point. These gapless Goldstone modes are the quantum carriers of information and entropy. Analyzing their effective theory, we observe the information-processing properties strikingly similar to the ones predicted by the black hole portrait. The energy cost per qubit of information-storage vanishes in the large-$N$ limit and the total information-storage capacity increases with $N$ either exponentially or as a power law. The longevity of information-storage also increases with $N$, whereas the scrambling time in the over-critical regime is controlled by the Lyapunov exponent and scales logarithmically with $N$. This connection reveals that the origin of black hole information storage lies in the quantum criticality of the graviton Bose-gas, and that much simpler systems that can be manufactured in table-top experiments can exhibit very similar information-processing dynamics.
Experimental Hall B | Jefferson Lab
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
take data in Hall B employ beams of either electrons or photons. From 1995 to 2012, the heart of the Hall B physics program involved the use of the CEBAF Large Acceptance...
Vacuum state truncation via the quantum Zeno effect
Tae-Gon Noh
2012-08-22
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.
Effective approach to non-relativistic quantum mechanics
Jacobs, David M
2015-01-01
Boundary conditions on non-relativistic wavefunctions are generally not completely constrained by the basic precepts of quantum mechanics, so understanding the set of possible self-adjoint extensions of the Hamiltonian is required. For real physical systems, non-trivial self-adjoint extensions have been used to model contact potentials when those interactions are expected a priori. However, they must be incorporated into the effective description of any quantum mechanical system in order to capture possible short-distance physics that does not decouple in the low energy limit. Here, an approach is described wherein an artificial boundary is inserted at an intermediate scale on which boundary conditions may encode short-distance effects that are hidden behind the boundary. Using this approach, an analysis is performed of the free particle, harmonic oscillator, and Coulomb potential in three dimensions. Requiring measurable quantities, such as spectra and cross sections, to be independent of this artificial bou...
Ab initio statistical mechanics of surface adsorption and desorption. II. Nuclear quantum effects
Alfè, Dario
systems for which quantum contributions to the free energy are known exactly from analytic arguments/mol. As a contribution to these developments, we present here a practical scheme for including quantum nuclear effectsAb initio statistical mechanics of surface adsorption and desorption. II. Nuclear quantum effects D
Novel Atomic Coherence and Interference Effects in Quantum Optics and Atomic Physics
Jha, Pankaj
2012-10-19
It is well known that the optical properties of multi-level atomic and molecular system can be controlled and manipulated efficiently using quantum coherence and interference, which has led to many new effects in quantum ...
Residence Hall Fire Safety Information Department of Public Safety Residential Life & Housing #12;Part 1 ! Building Information Pursuant to New York City Fire Code and Local Law 10, this Fire Safety, as well as what to do in a fire emergency. Building Construction Residential buildings built before 1968
Hall provided that capacity exists after fulfilling fulltime student demand and that affiliates Cards are issued by the registrar's office, but are encoded for residential use by the Student Housing are shared with a suite mate. Kitchen and laundry facilities are located on each residential floor. All rooms
Madami, M; Moriyama, T; Tanaka, K; Siracusano, G; Carpentieri, M; Finocchio, G; Tacchi, S; Ono, T; Carlotti, G
2015-01-01
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...
Dancheva, Y.; Biancalana, V.; Pagano, D.; Scortecci, F.
2013-06-15
Near exit plane non-resonant light induced fluorescence spectroscopy is performed in a Hall effect low-power Xenon thruster at discharge voltage of 250 V and anode flow rate of 0.7 mg/s. Measurements of the axial and radial velocity components are performed, exciting the 6s{sup 2}[3/2]{sub 2}{sup o}{yields}6p{sup 2}[3/2]{sub 2} transition at 823.16 nm in XeI and the 5d[4]{sub 7/2}{yields}6p[3]{sub 5/2}{sup o} transition at 834.724 nm in XeII. No significant deviation from the thermal velocity is observed for XeI. Two most probable ion velocities are registered at a given position with respect to the thruster axis, which are mainly attributed to different areas of creation of ions inside the acceleration channel. The spatial resolution of the set-up is limited by the laser beam size (radius of the order of 0.5 mm) and the fluorescence collection optics, which have a view spot diameter of 8 mm.
Nambu-Goldstone Effective Theory of Information at Quantum Criticality
Dvali, Gia; Gomez, Cesar; Wintergerst, Nico
2015-01-01
We establish a fundamental connection between quantum criticality of a many-body system, such as Bose-Einstein condensates, and its capacity of information-storage and processing. For deriving the effective theory of modes in the vicinity of the quantum critical point we develop a new method by mapping a Bose-Einstein condensate of $N$-particles onto a sigma model with a continuous global (pseudo)symmetry that mixes bosons of different momenta. The Bogolyubov modes of the condensate are mapped onto the Goldstone modes of the sigma model, which become gapless at the critical point. These gapless Goldstone modes are the quantum carriers of information and entropy. Analyzing their effective theory, we observe the information-processing properties strikingly similar to the ones predicted by the black hole portrait. The energy cost per qubit of information-storage vanishes in the large-$N$ limit and the total information-storage capacity increases with $N$ either exponentially or as a power law. The longevity of i...
Particle decay processes, the quantum Zeno effect and the continuity of time
George Jaroszkiewicz; Jon Eakins
2006-10-24
Signal-state quantum mechanics is used to discuss quantum mechanical particle decay probabilities and the quantum Zeno effect. This approach avoids the assumption of continuous time, conserves total probability and requires neither non-Hermitian Hamiltonians nor the ad-hoc introduction of complex energies. The formalism is applied to single channel decays, the ammonium molecule, and neutral Kaon decay processes.
Nikolic, Branislav K.
Mesoscopics in Spintronics: Quantum Interference Effects in Spin-Polarized Electron Transport to allow for envisioned quantum technologies that manipulate spin, such as spintronics1,2 or solid-state quantum computing with spin-qubits.3 Spintronic engi- neering of spin-polarized currents, combined
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
Kane, Charles
, University of Pennsylvania, Philadelphia, Pennsylvania 19104 Matthew P. A. Fisher Institute for Theoretical
Kane, Charles
of Physics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA (Received 28 October 2002
S. G. Tan; M. B. A. Jalil; X. -J. Liu; T. Fujita
2007-11-14
We describe formally the precession of spin vector about the k-space effective magnetic field in condensed matter system with spin orbital effects as constituting a local transformation of the electron wavefunction which necessarily invokes the SU(2) transformation rule to ensure covariance. We showed a "no-precession" condition as pre-requisite for the spin gauge field to exert its influence on spin particle motion. The effects of the spin gauge field on spin particle motion were shown to be consistent in both classical and quantum pictures, which hence should underpin theoretical explanations for important effects in anomalous Hall, spin Hall, spin torque, optical Magnus, geometric quantum computation.
Cylindrical geometry hall thruster
Raitses, Yevgeny (Princeton, NJ); Fisch, Nathaniel J. (Princeton, NJ)
2002-01-01
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.
Path Integral and Effective Hamiltonian in Loop Quantum Cosmology
Haiyun Huang; Yongge Ma; Li Qin
2011-06-27
We study the path integral formulation of Friedmann universe filled with a massless scalar field in loop quantum cosmology. All the isotropic models of $k=0,+1,-1$ are considered. To construct the path integrals in the timeless framework, a multiple group-averaging approach is proposed. Meanwhile, since the transition amplitude in the deparameterized framework can be expressed in terms of group-averaging, the path integrals can be formulated for both deparameterized and timeless frameworks. Their relation is clarified. It turns out that the effective Hamiltonian derived from the path integral in deparameterized framework is equivalent to the effective Hamiltonian constraint derived from the path integral in timeless framework, since they lead to same equations of motion. Moreover, the effective Hamiltonian constraints of above models derived in canonical theory are confirmed by the path integral formulation.
Semianalytical quantum model for graphene field-effect transistors
Pugnaghi, Claudio; Grassi, Roberto Gnudi, Antonio; Di Lecce, Valerio; Gnani, Elena; Reggiani, Susanna; Baccarani, Giorgio
2014-09-21
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
2011-02-01
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).
New Mathematical Tools for Quantum Technology
Christian Bracher; Manfred Kleber; Tobias Kramer
2007-03-01
Progress in manufacturing technology has allowed us to probe the behavior of devices on a smaller and faster scale than ever before. With increasing miniaturization, quantum effects come to dominate the transport properties of these devices, between collisions, carriers undergo ballistic motion under the influence of local electric and magnetic fields. The often surprising propertiesof quantum ballistic transport are currently elucidated in clean atomic physics experiments. From a theoretical viewpoint, theelectron dynamics is governed by ballistic propagators and Green functions, intriguing quantities at the crossroads of classical and quantum mechanics. Here, we briefly describe the propagator method, some ballistic Green functions, and their application in a diverse range of problems in atomic and solid state physics, such as photodetachment, atom lasers, scanning tunneling microscopy, and the quantum Hall effect.
Quantum noise effects with Kerr nonlinearity enhancement in coupled gain-loss waveguides
Bing He; Shu-Bin Yan; Jing Wang; Min Xiao
2015-05-26
It is generally difficult to study the dynamical properties of a quantum system with both inherent quantum noises and non-perturbative nonlinearity. Due to the possibly drastic intensity increase of an input coherent light in the gain-loss waveguide couplers with parity-time (PT) symmetry, the Kerr effect from a nonlinearity added into the systems can be greatly enhanced, and is expected to create the macroscopic entangled states of the output light fields with huge photon numbers. Meanwhile, the quantum noises also coexist with the amplification and dissipation of the light fields. Under the interplay between the quantum noises and nonlinearity, the quantum dynamical behaviors of the systems become rather complicated. However, the important quantum noise effects have been mostly neglected in the previous studies about nonlinear PT-symmetric systems. Here we present a solution to this non-perturbative quantum nonlinear problem, showing the real-time evolution of the system observables. The enhanced Kerr nonlinearity is found to give rise to a previously unknown decoherence effect that is irrelevant to the quantum noises, and imposes a limit on the emergence of macroscopic nonclassicality. In contrast to what happen in the linear systems, the quantum noises exert significant impact on the system dynamics, and can create the nonclassical light field states in conjunction with the enhanced Kerr nonlinearity. This first study on the noise involved quantum nonlinear dynamics of the coupled gain-loss waveguides can help to better understand the quantum noise effects in the broad nonlinear systems.
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
Kotera, N.; Tanaka, K.; Jones, E.D.
1997-06-01
Two-dimensional natures of energy-band and the effective mass of conduction subband in narrow InGaAs/InAlAs quantum well layers have been clarified via magneto-photoluminescence, cyclotron resonance, Shubnikov-de Haas oscillations and quantum Hall effect, interband optical transmittance, and photoluminescence. Heavy effective masses of 0.07m{sub 0} were determined in 5- and 10-nm-wide quantum wells, which were 70% larger than the bulk bandedge mass, 0.041m{sub 0}. Sheet carrier concentration in the quantum wells was as high as 1 x 10{sup 12} cm{sup {minus}2}.
Name Address Alumnae Hall 91 Alumnae Dr. EG
Arnold, Elizabeth A.
Name Address Alumnae Hall 91 Alumnae Dr. EG Anthony-Seeger Hall 821 S. Main EG Ashby Hall 50 Bluestone Dr. AUX Burruss Hall 820 Madison Dr. EG Cleveland Hall 61 E. Grace EG Converse Hall 30 Bluestone Dr. AUX Duke Hall 820 S. Main EG Mr. Chips Convenience Store 190 Bluestone Dr. AUX Frederikson Hall
The theta parameter in loop quantum gravity: effects on quantum geometry and black hole entropy
Danilo Jimenez Rezende; Alejandro Perez
2007-11-20
The precise analog of the theta-quantization ambiguity of Yang-Mills theory exists for the real SU(2) connection formulation of general relativity. As in the former case theta labels representations of large gauge transformations, which are super-selection sectors in loop quantum gravity. We show that unless theta=0, the (kinematical) geometric operators such as area and volume are not well defined on spin network states. More precisely the intersection of their domain with the dense set Cyl in the kinematical Hilbert space H of loop quantum gravity is empty. The absence of a well defined notion of area operator acting on spin network states seems at first in conflict with the expected finite black hole entropy. However, we show that the black hole (isolated) horizon area--which in contrast to kinematical area is a (Dirac) physical observable--is indeed well defined, and quantized so that the black hole entropy is proportional to the area. The effect of theta is negligible in the semiclassical limit where proportionality to area holds.
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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousandReport)PriceHistoricEnergyAprilMartin D. Kamen,Mary AnnHall
Office of Energy Efficiency and Renewable Energy (EERE)
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.
Effect of source tampering in the security of quantum cryptography
Sun, Shi-Hai
The security of source has become an increasingly important issue in quantum cryptography. Based on the framework of measurement-device-independent quantum key distribution (MDI-QKD), the source becomes the only region ...
MESOSCOPIC SPINTRONICS: FLUCTUATION AND LOCALIZATION EFFECTS IN SPIN-POLARIZED QUANTUM
Nikolic, Branislav K.
MESOSCOPIC SPINTRONICS: FLUCTUATION AND LOCALIZATION EFFECTS IN SPIN-POLARIZED QUANTUM TRANSPORT spintronic devices leads to a dramatic reduction of localization effects on the conductances to allow for envisioned quantum technologies that manipulate spin, such as spintronics1,2 or solid
Quantum nuclear effects on the location of hydrogen above and below the palladium (100) surface
Alavi, Ali
Quantum nuclear effects on the location of hydrogen above and below the palladium (100) surface functional calculation Quantum effect Path-integral Palladium Hydrogen We report ab initio path integral molecular dynamics simulations of hydrogen and deuterium adsorbed on and absorbed in the Pd(100) surface
Magnetoelectric transport and quantum interference effect in ultrathin manganite films
Wang, Cong; Jin, Kui-juan Gu, Lin; Lu, Hui-bin; Li, Shan-ming; Zhou, Wen-jia; Zhao, Rui-qiang; Guo, Hai-zhong; He, Meng; Yang, Guo-zhen
2014-04-21
The magnetoelectric transport behavior with respect to the thicknesses of ultrathin La{sub 0.9}Sr{sub 0.1}MnO{sub 3} films is investigated in detail. The metal-insulator phase transition, which has never been observed in bulk La{sub 0.9}Sr{sub 0.1}MnO{sub 3}, is found in ultrathin films with thicknesses larger than 6 unit cells. Low-temperature resistivity minima appeared in films with thicknesses less than 10 unit cells. This is attributed to the presence of quantum interference effects. These data suggest that the influence of the weak localization becomes much pronounced as the film thickness decreases from 16 to 8 unit cells.
Residence Hall Addresses Residence Hall Physical Street Address Zip Plus Four
- East 700 Washington St SW 24061-9521 Ambler Johnston Hall - West 720 Washington St SW 24061 Drillfield Dr 24061-9535 Campbell Hall - Main 300 Drillfield Dr 24061-9503 Cochrane Hall 770 Washington St SW 385 West Campus Dr 24061-9505 Johnson Hall 500 Washington St SW 24061-9506 Lee Hall 570 Washington St
Can One Trust Quantum Simulators?
Philipp Hauke; Fernando M. Cucchietti; Luca Tagliacozzo; Ivan Deutsch; Maciej Lewenstein
2012-07-26
Various fundamental phenomena of strongly-correlated quantum systems such as high-$T_c$ superconductivity, the fractional quantum-Hall effect, and quark confinement are still awaiting a universally accepted explanation. The main obstacle is the computational complexity of solving even the most simplified theoretical models that are designed to capture the relevant quantum correlations of the many-body system of interest. In his seminal 1982 paper [Int. J. Theor. Phys. 21, 467], Richard Feynman suggested that such models might be solved by "simulation" with a new type of computer whose constituent parts are effectively governed by a desired quantum many-body dynamics. Measurements on this engineered machine, now known as a "quantum simulator," would reveal some unknown or difficult to compute properties of a model of interest. We argue that a useful quantum simulator must satisfy four conditions: relevance, controllability, reliability, and efficiency. We review the current state of the art of digital and analog quantum simulators. Whereas so far the majority of the focus, both theoretically and experimentally, has been on controllability of relevant models, we emphasize here the need for a careful analysis of reliability and efficiency in the presence of imperfections. We discuss how disorder and noise can impact these conditions, and illustrate our concerns with novel numerical simulations of a paradigmatic example: a disordered quantum spin chain governed by the Ising model in a transverse magnetic field. We find that disorder can decrease the reliability of an analog quantum simulator of this model, although large errors in local observables are introduced only for strong levels of disorder. We conclude that the answer to the question "Can we trust quantum simulators?" is... to some extent.
Quantum fluctuations and isotope effects in ab initio descriptions of water
Wang, Lu; Markland, Thomas E.; Ceriotti, Michele
2014-09-14
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.
The effects of electron temperature in terahertz quantum cascade laser predictions
Massachusetts at Lowell, University of
establish a series of finite quantum wells that trap electrons. Additionally, a bias voltage is applied which provides electron pumping. In each period of the active region, electrons tunnel throughThe effects of electron temperature in terahertz quantum cascade laser predictions Philip
Acceleration of positrons by a relativistic electron beam in the presence of quantum effects
Niknam, A. R.; Aki, H.; Khorashadizadeh, S. M.
2013-09-15
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.
Experimental Hall C | Jefferson Lab
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
in Hall C is used to study the weak charge of the proton, form factors of simple quark systems, the transition from hadrons to quarks and nuclei with a strange quark embedded....
Office of Energy Efficiency and Renewable Energy (EERE)
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)
Optimization of Cylindrical Hall Thrusters
Yevgeny Raitses, Artem Smirnov, Erik Granstedt, and Nathaniel J. Fi
2007-07-24
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
2007-11-27
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.
Quantum effects in many-body gravitating systems
V. A. Golovko
2015-04-07
A hierarchy of equations for equilibrium reduced density matrices obtained earlier is used to consider systems of spinless bosons bound by forces of gravity alone. The systems are assumed to be at absolute zero of temperature under conditions of Bose condensation. In this case, a peculiar interplay of quantum effects and of very weak gravitational interaction between microparticles occurs. As a result, there can form spatially-bounded equilibrium structures macroscopic in size, both immobile and rotating. The size of a structure is inversely related to the number of particles in the structure. When the number of particles is relatively small the size can be enormous, whereas if this numbder equals Avogadro's number the radius of the structure is about 30 cm in the case that the structure consists of hydrogen atoms. The rotating objects have the form of rings and exhibit superfluidity. An atmosphere that can be captured by tiny celestial bodies from the ambient medium is considered too. The thickness of the atmosphere decreases as its mass increases. If short-range intermolecular forces are taken into account, the results obtained hold for excited states whose lifetime can however be very long. The results of the paper can be utilized for explaining the first stage of formation of celestial bodies from interstellar and even intergalactic gases.
Quantum effects in many-body gravitating systems
Golovko, V A
2015-01-01
A hierarchy of equations for equilibrium reduced density matrices obtained earlier is used to consider systems of spinless bosons bound by forces of gravity alone. The systems are assumed to be at absolute zero of temperature under conditions of Bose condensation. In this case, a peculiar interplay of quantum effects and of very weak gravitational interaction between microparticles occurs. As a result, there can form spatially-bounded equilibrium structures macroscopic in size, both immobile and rotating. The size of a structure is inversely related to the number of particles in the structure. When the number of particles is relatively small the size can be enormous, whereas if this numbder equals Avogadro's number the radius of the structure is about 30 cm in the case that the structure consists of hydrogen atoms. The rotating objects have the form of rings and exhibit superfluidity. An atmosphere that can be captured by tiny celestial bodies from the ambient medium is considered too. The thickness of the at...
A quantum-geometrical description of fracton statistics
Wellington da Cruz
2003-05-26
We consider the fractal characteristic of the quantum mechanical paths and we obtain for any universal class of fractons labeled by the Hausdorff dimension defined within the interval 1$ $$ < $$ $$h$$ $$ <$$ $$ 2$, a fractal distribution function associated with a fractal von Neumann entropy. Fractons are charge-flux systems defined in two-dimensional multiply connected space and they carry rational or irrational values of spin. This formulation can be considered in the context of the fractional quantum Hall effect-FQHE and number theory.
On the Compatibility Between Quantum and Relativistic Effects in an Electromagnetic Bridge Theory
Massimo Auci
2010-03-18
The Dipolar Electromagnetic Source (DEMS) model, based on the Poynting Vector Conjecture, conduces in Bridge Theory to a derivation of the Lorentz transformation connecting pairs of events. The results prove a full compatibility between quantum and relativistic effects.
Effect of noise on time-dependent quantum chaos
Ott, E.; Antonsen T.M. Jr.; Hanson, J.D.
1984-12-03
The dynamics of a time-dependent quantum system can be qualitatively different from that of its classical counterpart when the latter is chaotic. It is shown that small noise can strongly alter this situation.
Stability of Hall equilibria in neutron star crusts
Marchant, Pablo; Reisenegger, Andreas; Valdivia, Juan Alejandro; Hoyos, Jaime H.
2014-12-01
In the solid crusts of neutron stars, the advection of the magnetic field by the current-carrying electrons, an effect known as Hall drift, should play a very important role as the ions remain essentially fixed (as long as the solid does not break). Although Hall drift preserves the magnetic field energy, it has been argued that it may drive a turbulent cascade to scales at which ohmic dissipation becomes effective, allowing a much faster decay in objects with very strong fields. On the other hand, it has been found that there are 'Hall equilibria', i.e., field configurations that are unaffected by Hall drift. Here we address the crucial question of the stability of these equilibria through axially symmetric (two-dimensional (2D)) numerical simulations of Hall drift and ohmic diffusion, with the simplifying assumption of uniform electron density and conductivity. We demonstrate the 2D stability of a purely poloidal equilibrium, for which ohmic dissipation makes the field evolve toward an attractor state through adjacent stable configurations, around which damped oscillations occur. For this field, the decay scales with the ohmic timescale. We also study the case of an unstable equilibrium consisting of both poloidal and toroidal field components that are confined within the crust. This field evolves into a stable configuration, which undergoes damped oscillations superimposed on a slow evolution toward an attractor, just as the purely poloidal one.
Effect of source tampering in the security of quantum cryptography
Shi-Hai Sun; Feihu Xu; Mu-Sheng Jiang; Xiang-Chun Ma; Hoi-Kwong Lo; Lin-Mei Liang
2015-08-21
The security of source has become an increasingly important issue in quantum cryptography. Based on the framework of measurement-device-independent quantum-key-distribution (MDI-QKD), the source becomes the only region exploitable by a potential eavesdropper (Eve). Phase randomization is a cornerstone assumption in most discrete-variable (DV-) quantum communication protocols (e.g., QKD, quantum coin tossing, weak coherent state blind quantum computing, and so on), and the violation of such an assumption is thus fatal to the security of those protocols. In this paper, we show a simple quantum hacking strategy, with commercial and homemade pulsed lasers, by Eve that allows her to actively tamper with the source and violate such an assumption, without leaving a trace afterwards. Furthermore, our attack may also be valid for continuous-variable (CV-) QKD, which is another main class of QKD protocol, since, excepting the phase random assumption, other parameters (e.g., intensity) could also be changed, which directly determine the security of CV-QKD.
Competing quantum effects in the dynamics of a flexible water model
Scott Habershon; Thomas E. Markland; David E. Manolopoulos
2010-11-04
Numerous studies have identified large quantum mechanical effects in the dynamics of liquid water. In this paper, we suggest that these effects may have been overestimated due to the use of rigid water models and flexible models in which the intramolecular interactions were described using simple harmonic functions. To demonstrate this, we introduce a new simple point charge model for liquid water, q-TIP4P/F, in which the O--H stretches are described by Morse-type functions. We have parameterized this model to give the correct liquid structure, diffusion coefficient, and infra-red absorption frequencies in quantum (path integral-based) simulations. By comparing classical and quantum simulations of the liquid, we find that quantum mechanical fluctuations increase the rates of translational diffusion and orientational relaxation in our model by a factor of around 1.15. This effect is much smaller than that observed in all previous simulations of simple empirical water models, which have found a quantum effect of at least 1.4 regardless of the quantum simulation method or the water model employed. The small quantum effect in our model is a result of two competing phenomena. Intermolecular zero point energy and tunneling effects destabilize the hydrogen bonding network, leading to a less viscous liquid with a larger diffusion coefficient. However this is offset by intramolecular zero point motion, which changes the average water monomer geometry resulting in a larger dipole moment, stronger intermolecular interactions, and slower diffusion. We end by suggesting, on the basis of simulations of other potential energy models, that the small quantum effect we find in the diffusion coefficient is associated with the ability of our model to produce a single broad O-H stretching band in the infra-red absorption spectrum.
Hyodo, Kazushige Sakuma, Akimasa; Kota, Yohei
2014-05-07
We studied quantitative relationship between the intrinsic anomalous Hall conductivity (?{sub xy}) and the uniaxial magnetic anisotropy constant (K{sub u}) of bct-Fe{sub 50}Co{sub 50} using first-principles calculation because these quantities originate from spin-orbit interaction. We found that the obtained ?{sub xy} and K{sub u} with changing the axial ratio c/a (1?c/a??(2)) exhibit similar behavior mainly arising from the common band mixing of the minority-spin d{sub xy} and d{sub x{sup 2}?y{sup 2}} states near the Fermi level which is sensitive to c/a.
Shepelyansky, Dima
of Quantum Chaos and Imperfection Effects Pil Hun Song1 and Dima L. Shepelyansky2 1 Max-Planck-Institut fÃ¼r model in the regime of quantum chaos. It is shown that there are two types of physical characteristics of imperfection effects we analyze in this paper their influence on a quantum compu- tation of quantum chaos
City Hall plazas : they're different
Hall, Kristen E. (Kristen Elizabeth)
2008-01-01
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 ...
Eslami, L., E-mail: Leslami@iust.ac.ir; Faizabadi, E. [School of Physics, Iran University of Science and Technology, Tehran 16846 (Iran, Islamic Republic of)
2014-05-28
The effect of magnetic contacts on spin-dependent electron transport and spin-accumulation in a quantum ring, which is threaded by a magnetic flux, is studied. The quantum ring is made up of four quantum dots, where two of them possess magnetic structure and other ones are subjected to the Rashba spin-orbit coupling. The magnetic quantum dots, referred to as magnetic quantum contacts, are connected to two external leads. Two different configurations of magnetic moments of the quantum contacts are considered; the parallel and the anti-parallel ones. When the magnetic moments are parallel, the degeneracy between the transmission coefficients of spin-up and spin-down electrons is lifted and the system can be adjusted to operate as a spin-filter. In addition, the accumulation of spin-up and spin-down electrons in non-magnetic quantum dots are different in the case of parallel magnetic moments. When the intra-dot Coulomb interaction is taken into account, we find that the electron interactions participate in separation between the accumulations of electrons with different spin directions in non-magnetic quantum dots. Furthermore, the spin-accumulation in non-magnetic quantum dots can be tuned in the both parallel and anti-parallel magnetic moments by adjusting the Rashba spin-orbit strength and the magnetic flux. Thus, the quantum ring with magnetic quantum contacts could be utilized to create tunable local magnetic moments which can be used in designing optimized nanodevices.
Physics program in Hall A at CEBAF
Saha, A.
1990-01-01
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.
Effects of quantum space time foam in the neutrino sector
H. V. Klapdor-Kleingrothaus; H. Päs; U. Sarkar
2000-07-05
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.
Quantum optical effective-medium theory for loss-compensated metamaterials
Ehsan Amooghorban; N. Asger Mortensen; Martijn Wubs
2013-03-13
A central aim in metamaterial research is to engineer sub-wavelength unit cells that give rise to desired effective-medium properties and parameters, such as a negative refractive index. Ideally one can disregard the details of the unit cell and employ the effective description instead. A popular strategy to compensate for the inevitable losses in metallic components of metamaterials is to add optical gain material. Here we study the quantum optics of such loss-compensated metamaterials at frequencies for which effective parameters can be unambiguously determined. We demonstrate that the usual effective parameters are insufficient to describe the propagation of quantum states of light. Furthermore, we propose a quantum-optical effective-medium theory instead and show that it correctly predicts the properties of the light emerging from loss-compensated metamaterials.
Hall viscosity from elastic gauge fields in Dirac crystals
Cortijo, Alberto; Landsteiner, Karl; Vozmediano, María A H
2015-01-01
The combination of Dirac physics and elasticity has been explored at length in graphene where the so--called "elastic gauge fields" have given rise to an entire new field of research and applications: Straintronics. The fact that these elastic fields couple to fermions as the electromagnetic field, implies that many electromagnetic responses will have elastic counterparts not explored before. In this work we will first show that the presence of elastic gauge fields will be the rule rather than the exception in most of the topologically non--trivial materials in two and three dimensions. In particular we will extract the elastic gauge fields associated to the recently observed Weyl semimetals, the "three dimensional graphene". As it is known, quantum electrodynamics suffers from the chiral anomaly whose consequences have been recently explored in matter systems. We will show that, associated to the physics of the anomalies, and as a counterpart of the Hall conductivity, elastic materials will have a Hall visco...
Nanoconstriction-based spin-Hall nano-oscillator
Demidov, V. E.; Urazhdin, S.; Zholud, A.; Sadovnikov, A. V.; Demokritov, S. O.
2014-10-27
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.
Minnesota, University of
Ctr, ARSF-Agricultural Research Support Facility, CH-Centennial Hall, DH-Dowell Hall, DA-Dowell Hall
Tunneling of the 3rd Kind: A Test of the Effective Non-locality of Quantum Field Theory
Simon A. Gardiner; Holger Gies; Joerg Jaeckel; Chris J. Wallace
2013-04-09
Integrating out virtual quantum fluctuations in an originally local quantum field theory results in an effective theory which is non-local. In this Letter we argue that tunneling of the 3rd kind - where particles traverse a barrier by splitting into a pair of virtual particles which recombine only after a finite distance - provides a direct test of this non-locality. We sketch a quantum-optical setup to test this effect, and investigate observable effects in a simple toy model.
ANNUAL FIRE SAFETY RESIDENCE HALLS
Fernandez, Eduardo
1 2013 ANNUAL FIRE SAFETY REPORT FOR RESIDENCE HALLS As Required by the Higher Education Opportunity Act (HEOA) #12;2 INTRODUCTION Contents of this annual fire safety report reflect the requirements outlined in the HEOA, which are included in Florida Atlantic University's (FAU) campus fire safety program
Bonner Hall Building Evacuation Procedures
Krovi, Venkat
Bonner Hall Building Evacuation Procedures General Procedures: It is the personal responsibility of all occupants of University buildings to immediately exit the building when the fire alarm is activated. Remaining in the building is unacceptable, regardless of the reason. Occupants should exit from
KETTER HALL BUILDING EVACUATION PROCEDURES
Krovi, Venkat
KETTER HALL BUILDING EVACUATION PROCEDURES General Procedures: It is the personal responsibility of all University buildings occupants to immediately exit the building when the fire alarm is activated. Remaining in the building is unacceptable, regardless of the reason. Occupants should exit from the closest
Jarvis Hall Building Evacuation Procedures
Krovi, Venkat
Jarvis Hall Building Evacuation Procedures General Procedures: It is the personal responsibility of all occupants of University buildings to immediately exit the building when the fire alarm is activated. Remaining in the building is unacceptable, regardless of the reason. Occupants should exit from
Furnas Hall Building Evacuation Procedures
Krovi, Venkat
Furnas Hall Building Evacuation Procedures General Procedures: It is the personal responsibility of all occupants of University buildings to immediately exit the building when the fire alarm is activated. Remaining in the building is unacceptable, regardless of the reason. Occupants should exit from
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 online 25 September 2012 a b s t r a c t We quantify the influence of coupled electromechanical effects
Testing quantum-like models of judgment for question order effect
Thomas Boyer-Kassem; Sébastien Duchêne; Éric Guerci
2015-08-25
Lately, so-called "quantum" models, based on parts of the mathematics of quantum mechanics, have been developed in decision theory and cognitive sciences to account for seemingly irrational or paradoxical human judgments. We consider here some such quantum-like models that address question order effects, i.e. cases in which given answers depend on the order of presentation of the questions. Models of various dimensionalities could be used, can the simplest ones be empirically adequate? From the quantum law of reciprocity, we derive new empirical predictions that we call the Grand Reciprocity equations, that must be satisfied by several existing quantum-like models, in their non-degenerate versions. Using substantial existing data sets, we show that these non-degenerate versions fail the GR test in most cases, which means that, if quantum-like models of the kind considered here are to work, it can only be in their degenerate versions. However, we suggest that the route of degenerate models is not necessarily an easy one, and we argue for more research on the empirical adequacy of degenerate quantum-like models in general.
Hendra, P. I. B. Rahayu, F. Darma, Y.
2014-03-24
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.
Quantum simulations of localization effects with dipolar interactions
Gonzalo A. Alvarez; Robin Kaiser; Dieter Suter
2013-05-11
Quantum information processing often uses systems with dipolar interactions. We use a nuclear spin-based quantum simulator, to study the spreading of information in such a dipolar-coupled system and how perturbations to the dipolar couplings limit the spreading, leading to localization. In [Phys. Rev. Lett. 104, 230403 (2010)], we found that the system reaches a dynamic equilibrium size, which decreases with the square of the perturbation strength. Here, we study the impact of a disordered Hamiltonian with dipolar 1/r^3 interactions. We show that the expansion of the coherence length of the cluster size of the spins becomes frozen in the presence of large disorder, reminiscent of Anderson localization of non-interacting waves in a disordered potential.
A molecular dynamics study of nuclear quantum effect on the diffusion of hydrogen in condensed phase
Nagashima, Hiroki; Tokumasu, Takashi; Tsuda, Shin-ichi; Tsuboi, Nobuyuki; Koshi, Mitsuo; Hayashie, A. Koichi
2014-10-06
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.
Anyonic statistics and large horizon diffeomorphisms for Loop Quantum Gravity Black Holes
Andreas G. A. Pithis; Hans-Christian Ruiz Euler
2015-03-24
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.
Modeling effective FRW cosmologies with perfect fluids from states of the hybrid quantum Gowdy model
Beatriz Elizaga Navascués; Mercedes Martín-Benito; Guillermo A. Mena Marugán
2015-01-22
We employ recently developed approximation methods in the hybrid quantization of the Gowdy $T^3$ model with linear polarization and a massless scalar field to obtain physically interesting solutions of this inhomogeneous cosmology. More specifically, we propose approximate solutions of the quantum Gowdy model constructed in such a way that, for the Hamiltonian constraint, they effectively behave as those corresponding to a flat homogeneous and isotropic universe filled with a perfect fluid, even though these quantum states are far from being homogeneous and isotropic. We analyze how one can get different perfect fluid effective behaviors, including the cases of dust, radiation, and cosmological constant.
Deformed Hamilton-Jacobi Method in Covariant Quantum Gravity Effective Models
Mu Benrong; Peng Wang; Haitang Yang
2014-08-21
We first briefly revisit the original Hamilton-Jacobi method and show that the Hamilton-Jacobi equation for the action $I$ of tunnelings of a fermionic particle from a charged black hole can be written in the same form as that of a scalar particle. For the low energy quantum gravity effective models which respect covariance of the curved spacetime, we derive the deformed model-independent KG/Dirac and Hamilton-Jacobi equations using the methods of effective field theory. We then find that, to all orders of the effective theories, the deformed Hamilton-Jacobi equations can be obtained from the original ones by simply replacing the mass of emitted particles $m$ with a parameter $m_{eff}$ that includes all the quantum gravity corrections. Therefore, in this scenario, there will be no corrections to the Hawking temperature of a black hole from the quantum gravity effects if its original Hawking temperature is independent of the mass of emitted particles. As a consequence, our results show that breaking covariance in quantum gravity effective models is a key for a black hole to have the remnant left in the evaporation.
Quantum effects in spontaneous emission by a relativistic, undulating electron beam
G. R. M. Robb; R. Bonifacio
2011-10-27
Current models of the effect of spontaneous emission on the electron beam dynamics neglect the discreteness of electron recoil associated with photon emission. We present a novel, one-dimensional model of the effect of spontaneous emission on the electron beam dynamics in an undulator both in the classical regime where discrete electron recoil is negligible, and the quantum regime where it is significant. It is shown that in the classical regime, continuous decrease of the average electron energy and diffusive growth of the electron energy spread occurs, in agreement with previous classical models. In the quantum regime, it is shown that the evolution of the electron momentum distribution occurs as discrete momentum groups according to a Poisson distribution. The narrow momentum features of the quantum regime may be useful for generation of coherent radiation, which relies on electron beams having sufficiently narrow momentum/energy distributions.
Jahn-Teller versus quantum effects in the spin-orbital material LuVO3
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Skoulatos, M.; Toth, S.; Roessli, B.; Enderle, M.; Habicht, K.; Sheptyakov, D.; Cervellino, A.; Freeman, P. G.; Reehuis, M.; Stunault, A.; et al
2015-04-13
In this article, we report on combined neutron and resonant x-ray scattering results, identifying the nature of the spin-orbital ground state and magnetic excitations in LuVO3 as driven by the orbital parameter. In particular, we distinguish between models based on orbital-Peierls dimerization, taken as a signature of quantum effects in orbitals, and Jahn-Teller distortions, in favor of the latter. In order to solve this long-standing puzzle, polarized neutron beams were employed as a prerequisite in order to solve details of the magnetic structure, which allowed quantitative intensity analysis of extended magnetic-excitation data sets. The results of this detailed study enabledmore »us to draw definite conclusions about the classical versus quantum behavior of orbitals in this system and to discard the previous claims about quantum effects dominating the orbital physics of LuVO3 and similar systems.« less
Nikolic, Branislav K.
Modulating unpolarized current in quantum spintronics: Visibility of spin-interference effects. INTRODUCTION Recent attempts in spintronics1 to harness electron spin for classical and quantum information spintronic device, the Datta-Das spin-field-effect transistor4 (spin-FET) where current passing through a two
Vanderbilt, David
Effects of linear and nonlinear piezoelectricity on the electronic properties of InAs/GaAs quantum linear piezoelectric ef- fect into account and demonstrating important electronic consequences of the piezoelectric effect on electronic and optical properties of quantum dots and find that the quadratic and linear
Diederik Aerts; Massimiliano Sassoli de Bianchi
2015-08-15
A general tension-reduction (GTR) model was recently considered to derive quantum probabilities as (universal) averages over all possible forms of non-uniform fluctuations, and explain their considerable success in describing experimental situations also outside of the domain of physics, for instance in the ambit of quantum models of cognition and decision. Yet, this result also highlighted the possibility of observing violations of the predictions of the Born rule, in those situations where the averaging would not be large enough, or would be altered because of the combination of multiple measurements. In this article we show that this is indeed the case in typical psychological measurements exhibiting question order effects, by showing that their statistics of outcomes are inherently non-Hilbertian, and require the larger framework of the GTR-model to receive an exact mathematical description. We also consider another unsolved problem of quantum cognition: response replicability. It is has been observed that when question order effects and response replicability occur together, the situation cannot be handled anymore by quantum theory. However, we show that it can be easily and naturally described in the GTR-model. Based on these findings, we motivate the adoption in cognitive science of a hidden-measurements interpretation of the quantum formalism, and of its GTR-model generalization, as the natural interpretational framework explaining the data of psychological measurements on conceptual entities.
Magnetic field sensing beyond the standard quantum limit under the effect of decoherence
Matsuzaki, Yuichiro; Benjamin, Simon C.; Fitzsimons, Joseph
2011-07-15
Entangled states can potentially be used to outperform the standard quantum limit by which every classical sensor is bounded. However, entangled states are very susceptible to decoherence, and so it is not clear whether one can really create a superior sensor to classical technology via a quantum strategy which is subject to the effect of realistic noise. This paper presents an investigation of how a quantum sensor composed of many spins is affected by independent dephasing. We adopt general noise models including non-Markovian effects, and in these noise models the performance of the sensor depends crucially on the exposure time of the sensor to the field. We have found that, by choosing an appropriate exposure time within the non-Markovian time region, an entangled sensor does actually beat the standard quantum limit. Since independent dephasing is one of the most typical sources of noise in many systems, our results suggest a practical and scalable approach to beating the standard quantum limit.
Unknown
2005-06-30
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...
Non-singular bounce scenarios in loop quantum cosmology and the effective field description
Cai, Yi-Fu; Wilson-Ewing, Edward E-mail: wilson-ewing@phys.lsu.edu
2014-03-01
A non-singular bouncing cosmology is generically obtained in loop quantum cosmology due to non-perturbative quantum gravity effects. A similar picture can be achieved in standard general relativity in the presence of a scalar field with a non-standard kinetic term such that at high energy densities the field evolves into a ghost condensate and causes a non-singular bounce. During the bouncing phase, the perturbations can be stabilized by introducing a Horndeski operator. Taking the matter content to be a dust field and an ekpyrotic scalar field, we compare the dynamics in loop quantum cosmology and in a non-singular bouncing effective field model with a non-standard kinetic term at both the background and perturbative levels. We find that these two settings share many important properties, including the result that they both generate scale-invariant scalar perturbations. This shows that some quantum gravity effects of the very early universe may be mimicked by effective field models.
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS 1 Modeling of Terahertz Heating Effects in
Ganesan, Sashikumaar
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS 1 Modeling of Terahertz Heating Effects model that provides numerical solutions to the heat conduction equation coupled with realistic models as a consequence of THz absorption is determined by the heat transfer mechanisms of conduction, convection
Hammes-Schiffer, Sharon
Multiconfigurational nuclear-electronic orbital approach: Incorporation of nuclear quantum effects 26 March 2002; accepted 30 May 2002 The nuclear-electronic orbital NEO method for the calculation of mixed nuclear-electronic wave functions is presented. Both electronic and nuclear molecular orbitals
The Effect of Transverse Energy on Electronic Bound States in Heterostructure Quantum Wells
Mohanty, Saraju P.
that will be the subject of this work, is the precise form of the energy-wave vector (E(k)) relation and its deviation fromThe Effect of Transverse Energy on Electronic Bound States in Heterostructure Quantum Wells Elias Kougianos1 and Saraju P. Mohanty2 1Dept of Engineering Technology, University of North Texas, Denton, TX
arXiv:0907.4122v1[cond-mat.mes-hall]23Jul2009 SPIN CURRENTS IN SEMICONDUCTOR
Nikolic, Branislav K.
arXiv:0907.4122v1[cond-mat.mes-hall]23Jul2009 SPIN CURRENTS IN SEMICONDUCTOR NANOSTRUCTURES Handbook on Nanoscience and Technology: Frontiers and Advances Eds. A. V. Narlikar and Y. Y. Fu (Oxford-HALL EFFECT? 8 6 SO COUPLINGS IN LOW-DIMENSIONAL SEMICONDUCTORS 10 6.1 Rashba coupling in bulk 2DEG
Quantum Field Effects in Stationary Electron Spin Resonance Spectroscopy
Dmitri Yerchuck; Vyacheslav Stelmakh; Yauhen Yerchak; Alla Dovlatova
2015-01-28
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.
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.
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
Rebuilding It Better: Greensburg, Kansas, City Hall
D. Egan
2010-04-13
This document showcases the LEED-Platinum designed Greensburg City Hall, which was rebuilt green, after a massive tornado destroyed Greensburg, Kansas in May 2007.
September 10, 2010 Web Town Hall about UC Benefits
Leistikow, Bruce N.
September 10, 2010 Web Town Hall about UC Benefits UC leaders will host an online town hall meeting up for an account here: http://www.ustream.tv/login-signup. The Web Town Hall, a first in UC history
Gennady P. Berman; Fausto Borgonovi; Diego A. R. Dalvit
2008-01-29
We review our results on a mathematical dynamical theory for observables for open many-body quantum nonlinear bosonic systems for a very general class of Hamiltonians. We show that non-quadratic (nonlinear) terms in a Hamiltonian provide a singular "quantum" perturbation for observables in some "mesoscopic" region of parameters. In particular, quantum effects result in secular terms in the dynamical evolution, that grow in time. We argue that even for open quantum nonlinear systems in the deep quasi-classical region, these quantum effects can survive after decoherence and relaxation processes take place. We demonstrate that these quantum effects in open quantum systems can be observed, for example, in the frequency Fourier spectrum of the dynamical observables, or in the corresponding spectral density of noise. Estimates are presented for Bose-Einstein condensates, low temperature mechanical resonators, and nonlinear optical systems prepared in large amplitude coherent states. In particular, we show that for Bose-Einstein condensate systems the characteristic time of deviation of quantum dynamics for observables from the corresponding classical dynamics coincides with the characteristic time-scale of the well-known quantum nonlinear effect of phase diffusion.
Freezing a Coherent Field Growth in a Cavity by Quantum Zeno Effect
Julien Bernu; Samuel Deléglise; Clément Sayrin; Stefan Kuhr; Igor Dotsenko; Michel Brune; Jean-Michel Raimond; Serge Haroche
2008-09-25
We have frozen the coherent evolution of a field in a cavity by repeated measurements of its photon number. We use circular Rydberg atoms dispersively coupled to the cavity mode for an absorption-free photon counting. These measurements inhibit the growth of a Field injected in the cavity by a classical source. This manifestation of the Quantum Zeno effect illustrates the back action of the photon number determination onto the Field phase. The residual growth of the Field can be seen as a random walk of its amplitude in the two-dimensional phase space. This experiment sheds light onto the measurement process and opens perspectives for active quantum feedback.
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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorking With U.S.Week DayDr.Theories81Towards HeavyCoupled Earth System8, 2014
Shepelyansky, Dima
arXiv:quant-ph/0407264v130Jul2004 Effects of decoherence and imperfections for quantum algorithms A gates on the stability of various quantum algorithms including the Grover quantum search algorithm and the quantum chaos maps. For the Grover algorithm our numerical and analytical results show existence
Effects of stacking faults on the electronic structures of quantum rods
Wang, Lin-Wang
2004-03-30
Atomistic semiempirical pseudopotential method is used to study the effects of stacking faults in a wurtzite structure quantum rod. It is found that a single stacking fault can cause a 10-50 meV change in the conduction state eigen energy, and a localization in the electron wave function. However, the effects on the hole eigen energies and wave functions are very small.
Demir, Hilmi Volkan
GaN/GaN light-emitting diodes (LEDs) grown along the polar orientations significantly suffer from the quantum avoiding the electric field in the quantum wells. Consequently, the optical output power and the external quantum efficiency are substantially improved for the LEDs. The ability to self-screen the QCSE using
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
Building America Top Innovations Hall of Fame Profile - Building...
Top Innovations Hall of Fame Profile - Building Energy Optimization Analysis Method (BEopt) Building America Top Innovations Hall of Fame Profile - Building Energy Optimization...
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...
Effective Field Theory out of Equilibrium: Brownian quantum fields
D. Boyanovsky
2015-06-19
The emergence of an effective field theory out of equilibrium is studied in the case in which a light field --the system-- interacts with very heavy fields in a finite temperature bath. We obtain the reduced density matrix for the light field, its time evolution is determined by an effective action that includes the \\emph{influence action} from correlations of the heavy degrees of freedom. The non-equilibrium effective field theory yields a Langevin equation of motion for the light field in terms of dissipative and noise kernels that obey a generalized fluctuation dissipation relation. These are completely determined by the spectral density of the bath which is analyzed in detail for several cases. At $T=0$ we elucidate the effect of thresholds in the renormalization aspects and the asymptotic emergence of a local effective field theory with unitary time evolution. At $T\
Town Hall with Secretary Moniz
Energy Secretary Ernest Moniz; Deputy Secretary of Energy Daniel Poneman
2013-07-18
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
2013-07-25
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.
Compact modeling of quantum effects in double gate MOSFETs
Wang, Wei
2007-01-01
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
Vladimir A. Miransky; Igor A. Shovkovy
2015-04-10
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...
A. R. Bosco de Magalhães; J. G. Peixoto de Faria; R. Rossi Jr
2015-05-22
We investigate the role of the environment in a quantum erasure setup in the cavity quantum electrodynamics domain. Two slightly different schemes are analyzed. We show that the effects of the environment vary when a scheme is exchanged for another. This can be used to estimate the macroscopic parameters related to the system-environment microscopic correlations.
Scanning Hall Probe Microscopy of Magnetic Vortices inVery Underdoped yttrium-barium-copper-oxide
Guikema, Janice Wynn; /SLAC, SSRL
2005-12-02
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.
Deformed Hamilton-Jacobi Method in Covariant Quantum Gravity Effective Models
Benrong, Mu; Yang, Haitang
2014-01-01
We first briefly revisit the original Hamilton-Jacobi method and show that the Hamilton-Jacobi equation for the action $I$ of tunnelings of a fermionic particle from a charged black hole can be written in the same form as that of a scalar particle. For the low energy quantum gravity effective models which respect covariance of the curved spacetime, we derive the deformed model-independent KG/Dirac and Hamilton-Jacobi equations using the methods of effective field theory. We then find that, to all orders of the effective theories, the deformed Hamilton-Jacobi equations can be obtained from the original ones by simply replacing the mass of emitted particles $m$ with a parameter $m_{eff}$ that includes all the quantum gravity corrections. Therefore, in this scenario, there will be no corrections to the Hawking temperature of a black hole from the quantum gravity effects if its original Hawking temperature is independent of the mass of emitted particles. As a consequence, our results show that breaking covariance...
Effects of Quantum Confinement on the Doping Limit of Semiconductor
Wu, Junqiao
. The magnitude of this effect in a given material is found to be determined by two material properties of semiconductor nanostructures in terms of their fundamental material parameters. Doping limits in various bulk are generated in semiconductor materials in response to extrinsic doping so as to pull EF back toward EFS
The Aharonov-Bohm effect: A quantum or a relativistic phenomenon?
K. Wilhelm; B. N. Dwivedi
2014-08-23
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.
P. Pfeiffer; I. L. Egusquiza; M. Di Ventra; M. Sanz; E. Solano
2015-11-06
Technology based on memristors, resistors with memory whose resistance depends on the history of the crossing charges, has lately enhanced the classical paradigm of computation with neuromorphic architectures. However, in contrast to the known quantized models of passive circuit elements, such as inductors, capacitors or resistors, the design and realization of a quantum memristor is still missing. Here, we introduce the concept of a quantum memristor as a quantum dissipative device, whose decoherence mechanism is controlled by a continuous-measurement feedback scheme, which accounts for the memory. Indeed, we provide numerical simulations showing that memory effects actually persist in the quantum regime. Our quantization method, specifically designed for superconducting circuits, may be extended to other quantum platforms, allowing for memristor-type constructions in different quantum technologies. The proposed quantum memristor is then a building block for neuromorphic quantum computation and quantum simulations of non-Markovian systems.
Effect of laser phase noise on the fidelity of optomechanical quantum memory
Farnaz Farman; Alireza Bahrampour
2015-03-15
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.
Switching effect upon the quantum Brownian motion near a reflecting boundary
Masafumi Seriu; Chun-Hsien Wu
2007-11-16
The quantum Brownian motion of a charged particle in the electromagnetic vacuum fluctuations is investigated near a perfectly reflecting flat boundary, taking into account the smooth switching process in the measurement. Constructing a smooth switching function by gluing together a plateau and the Lorentzian switching tails, it is shown that the switching tails have a great influence on the measurement of the Brownian motion in the quantum vacuum. Indeed, it turns out that the result with a smooth switching function and the one with a sudden switching function are qualitatively quite different. It is also shown that anti-correlations between the switching tails and the main measuring part plays an essential role in this switching effect. The switching function can also be interpreted as a prototype of an non-equilibrium process in a realistic measurement, so that the switching effect found here is expected to be significant in actual applications in vacuum physics.
Noise effects in a three-player Prisoner's Dilemma quantum game
M. Ramzan; M. K. Khan
2009-02-16
We study the three-player Prisoner's Dilemma game under the effect of decoherence and correlated noise. It is seen that the quantum player is always better off over the classical players. It is also seen that the game's Nash equilibrium does not change in the presence of correlated noise in contradiction to the effect of decoherence in multiplayer case. Furthermore, it is shown that for maximum correlation the game does not behave as a noiseless game and the quantum player is still better off for all values of the decoherence parameter p which is not possible in the two-player case. In addition, the payoffs reduction due to decoherence is controlled by the correlated noise throughout the course of the game.
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
Gerber, U.; Wiese, U.-J.; Hofmann, C. P.; Kaempfer, F.
2010-02-01
We consider a microscopic model for a doped quantum ferromagnet as a test case for the systematic low-energy effective field theory for magnons and holes, which is constructed in complete analogy to the case of quantum antiferromagnets. In contrast to antiferromagnets, for which the effective field theory approach can be tested only numerically, in the ferromagnetic case, both the microscopic and the effective theory can be solved analytically. In this way, the low-energy parameters of the effective theory are determined exactly by matching to the underlying microscopic model. The low-energy behavior at half-filling as well as in the single- and two-hole sectors is described exactly by the systematic low-energy effective field theory. In particular, for weakly bound two-hole states the effective field theory even works beyond perturbation theory. This lends strong support to the quantitative success of the systematic low-energy effective field theory method not only in the ferromagnetic but also in the physically most interesting antiferromagnetic case.
K-7109Agnew Hall M-2204Air Conditioning Plant
K-7109Agnew Hall M-2204Air Conditioning Plant M-833Ambler Johnston Hall - East Wing M-832Ambler is an equal opportunity, affirmative action institution. K-7109 Agnew Hall 460 West Campus Dr M-2204 Air Conditioning Plant 344 Stanger St M-833 Ambler Johnston Hall - East Wing 700 Washington St SW M-832 Ambler
Intermittency in Hall-magnetohydrodynamics with a strong guide field
Rodriguez Imazio, P.; Martin, L. N.; Dmitruk, P.; Mininni, P. D.; National Center for Atmospheric Research, P.O. Box 3000, Boulder, Colorado 80307
2013-05-15
We present a detailed study of intermittency in the velocity and magnetic field fluctuations of compressible Hall-magnetohydrodynamic turbulence with an external guide field. To solve the equations numerically, a reduced model valid when a strong guide field is present is used. Different values for the ion skin depth are considered in the simulations. The resulting data are analyzed computing field increments in several directions perpendicular to the guide field, and building structure functions and probability density functions. In the magnetohydrodynamic limit, we recover the usual results with the magnetic field being more intermittent than the velocity field. In the presence of the Hall effect, field fluctuations at scales smaller than the ion skin depth show a substantial decrease in the level of intermittency, with close to monofractal scaling.
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)
2014-01-28
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.
Charging effects and quantum crossover in granular superconductors
Granato, E. (LAS, Instituto Nacional de Pesquisas Espaciais, 12.225 Sao Jose dos Campos, Sao Paulo (Brazil)); Continentino, M.A. (Instituto de Fisica, Universidade Federal Fluminense, Outeiro de S.J. Batista s/n, Niteroi, 24.020, Rio de Janeiro (Brazil))
1993-12-01
The effects of the charging energy in the superconducting transition of granular materials or Josephson-junction arrays are investigated using a pseudo-spin-one model. Within a mean-field renormalization-group approach, we obtain the phase diagram as a function of temperature and charging energy. In contrast to earlier treatments, we find no sign of a reentrant transition in agreement with more recent studies. A crossover line is identified in the nonsuperconducting side of the phase diagram and along which we expect to observe anomalies in the transport and thermodynamic properties. We also study a charge ordering phase, which can appear for large nearest-neighbor Coulomb interaction, and show that it leads to first-order transitions at low temperatures. We argue that, in the presence of charge ordering, a nonmonotonic behavior with decreasing temperature is possible with a maximum in the resistance just before entering the superconducting phase.
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)
2014-05-28
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.
Petta, Jason
of termination of enrollment and submitted to the Office of Academic Affairs of the Graduate School in Clio Hall for Termination (Select one of the items below): r All degree requirements have been completed. Date of Final Public Oral Examination (where applicable): r Enrollment Terminated, Degree Candidacy Continues (ET
Drew, H. Dennis
. Schmadel,1 G. S. Jenkins,1 H. D. Drew,1 R. Hughes,2 A. Dabkowski,2 J. S. Preston,2 and P.-J. Kung3 1 Center in High-Tc Superconductors: Evidence for Non-Fermi-Liquid Hall Scattering J. Cerne,1, * M. Grayson,1 D. C
A possible cosmological effect on the quantum-to-classical transition
C. L. Herzenberg
2006-03-16
Although cosmic expansion at very small distances is usually dismissed as entirely inconsequential, these extraordinarily small effects may in fact have a real and significant influence on our world. A calculation suggests that the minute recessional velocities associated with regions encompassed by extended bodies may have a role in creating the distinction between quantum and classical behavior. Using the criterion that the uncertainty in position should be smaller than the size of an object together with estimates based on the range of Hubble velocities extending through the object lead to a threshold size that could provide a fundamental limit distinguishing the realm of objects governed by classical laws from those governed by quantum mechanics.
Nuclear quantum effects in water exchange around lithium and fluoride ions
Wilkins, David M; Dang, Liem X
2015-01-01
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...
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)
2014-06-21
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.
UNIVERSITY VIEW GLENN L. MARTIN HALL
Daume III, Hal
other parking lots are for use by PERMIT HOL HALL BENJAMIN BUILDING SCHOOL OF PUBLIC HEALTH ARCHITECTURE A.V. WILLIAMS TERRAPIN SOFTBALL COMPLEXVisitors: · Parking is primarily designated within cashier-attended facilities. Lots are marked with on map
A new town hall for Norwich, Vermont
Harboe, Peter Thomas McIlvaine
1988-01-01
... the public building is not an abstract symbol, but partakes in daily life, which relates to what is timeless and common. The objective of this thesis was to design a new town hall for Norwich, Vermont. The design ...
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)
2013-11-25
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.
Effect of matrix on InAs self-organized quantum dots on InP substrate
Ustinov, V.M.; Weber, E.R.; Ruvimov, S.; Liliental-Weber, Z.; Zhukov, A.E.; Egorov, A.Y.; Kovsh, A.R.; Tsatsulnikov, A.F.; Kopev, P.S.
1998-01-01
InAs self-organized quantum dots in In{sub 0.53}Ga{sub 0.47}As and In{sub 0.52}Al{sub 0.48}As matrices have been grown on InP substrates by molecular beam epitaxy. The dot size in InGaAs has been found to be 3{endash}4 times larger, but the areal density about an order of magnitude smaller than that in InAlAs. Low-temperature photoluminescence (PL) of the InAs/InGaAs quantum dots is characterized by a narrow (35 meV) PL line as compared to that of InAs/InAlAs quantum dots (170 meV). Quantum dot formation increases the carrier localization energy as compared to quantum well structures with the same InAs thickness in a similar manner for both InAs/InGaAs and InAs/InAlAs structures. The effect of the barrier band gap on the optical transition energy is qualitatively the same for quantum well and quantum dot structures. The results demonstrate a possibility of controlling the quantum dot emission wavelength by varying the matrix composition. {copyright} {ital 1998 American Institute of Physics.}
Quantum Mechanical Inclusion of the Source in the Aharonov-Bohm Effect
Philip Pearle; Anthony Rizzi
2015-06-30
The standard treatment of the magnetic Aharonov-Bohm (A-B) effect assumes one can calculate the phase without accounting for the source (solenoid) quantum mechanically. Recently, Vaidman, using a semi-classical calculation, showed that the source may indeed matter. He argued for what might be called a local field hypothesis---the idea that in quantum theory, as in classical physics, only field-producing potentials have physical effects. His calculation indicates that the electron's non-relativistic electric field, acting on a semi-classically treated solenoid, produces the A-B phase shift. Here, employing a model of the solenoid consisting of charged particles, we give a quantum mechanical treatment of their contribution to the phase shift under the influence of the circulating electron's electric field. We show that the phase shift of the field-producing non-relativistic vector potential gives the A-B phase shift, and how this confirms Vaidman's semi-classical prediction of that phase shift. However, we also show that the phase shift of the field-producing relativistic (retarded) scalar potential gives the negative of the A-B phase shift. This cancellation allows one to effectively treat the source as a classical entity as is done in the standard derivation of the A-B effect. We close by remarking that the apparent necessity for relativistic considerations suggests the possibility that the A-B phase shift may yet be explained in terms of field-producing potentials alone, which may vindicate the local field hypothesis.
Shepelyansky, Dima
of various applica- tions in quantum computation, including the simulation of quantum chaos models showing, including treatment of large databases, data and image compression, signal process- ing, telecommunications
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
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)
2014-08-18
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.
Stapp, Henry P.
2011-05-10
The principle of sufficient reason asserts that anything that happens does so for a reason: no definite state of affairs can come into being unless there is a sufficient reason why that particular thing should happen. This principle is usually attributed to Leibniz, although the first recorded Western philosopher to use it was Anaximander of Miletus. The demand that nature be rational, in the sense that it be compatible with the principle of sufficient reason, conflicts with a basic feature of contemporary orthodox physical theory, namely the notion that nature's response to the probing action of an observer is determined by pure chance, and hence on the basis of absolutely no reason at all. This appeal to pure chance can be deemed to have no rational fundamental place in reason-based Western science. It is argued here, on the basis of the other basic principles of quantum physics, that in a world that conforms to the principle of sufficient reason, the usual quantum statistical rules will naturally emerge at the pragmatic level, in cases where the reason behind nature's choice of response is unknown, but that the usual statistics can become biased in an empirically manifest way when the reason for the choice is empirically identifiable. It is shown here that if the statistical laws of quantum mechanics were to be biased in this way then the basically forward-in-time unfolding of empirical reality described by orthodox quantum mechanics would generate the appearances of backward-time-effects of the kind that have been reported in the scientific literature.
Quantum effects on Lagrangian points and displaced periodic orbits in the Earth-Moon system
Emmanuele Battista; Simone Dell'Agnello; Giampiero Esposito; Jules Simo
2015-03-31
Recent work in the literature has shown that 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., at the Lagrangian libration points of stable equilibrium the planetoid is not exactly at equal distance from the two bodies of large mass, but the Newtonian values of its coordinates are changed by a few millimeters in the Earth-Moon system. First, we assess such a theoretical calculation by exploiting the full theory of the quintic equation, i.e., its reduction to Bring-Jerrard form and the resulting expression of roots in terms of generalized hypergeometric functions. By performing the numerical analysis of the exact formulas for the roots, we confirm and slightly improve the theoretical evaluation of quantum corrected coordinates of Lagrangian libration points of stable equilibrium. Second, we prove in detail that also for collinear Lagrangian points the quantum corrections are of the same order of magnitude in the Earth-Moon system. Third, 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, both stable and unstable. The present paper investigates therefore, eventually, a restricted three-body problem involving Earth, Moon and a solar sail. By taking into account the one-loop quantum corrections to the Newtonian potential, displaced periodic orbits of the solar sail at libration points are again found to exist.
Kalisz, Susan
F1 · Old Engineering Hall ....................OEH D2 Oxford Bldg.(3501 Forbes Ave.) OXFRD C4.............................BELLH G2 Bellefield Presbyterian Church...PRES D3 Bellefield Towers.........................BELLT F1 ....................CHILD C3 Clapp Hall..................................CLAPP F1 Community of Reconciliation Bldg. ..CR F1
Georgiou, C.; Leontiou, T.; Kelires, P. C.
2014-07-15
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.
Hybridization and the effective mass of quantum-well states in magnetic multilayers
Johnson, P.D.; Garrison, K.; Dong, Q. ); Smith, N.V. ); Li, D.; Mattson, J.; Pearson, J.; Bader, S.D. )
1994-09-15
Angle-resolved-photoemission studies of the dispersion of the quantum-well states in copper thin films deposited on a Co(001) substrate reveal that hybridization in the interface leads to a large increase in the effective mass of the electrons. These observations have implications for theories of the oscillatory exchange coupling in the related magnetic multilayers, particularly where Fermi-surface spanning vectors away from the center of the zone are invoked as in the case of the short-period oscillation in the Co/Cu(001) multilayers.
Jackson, Robert L.; Crandall, Erika R.; Bozack, Michael J.
2015-05-21
The objective of this work is to evaluate the effect of scale dependent mechanical and electrical properties on electrical contact resistance (ECR) between rough surfaces. This work attempts to build on existing ECR models that neglect potentially important quantum- and size-dependent contact and electrical conduction mechanisms present due to the asperity sizes on typical surfaces. The electrical conductance at small scales can quantize or show a stepping trend as the contact area is varied in the range of the free electron Fermi wavelength squared. This work then evaluates if these effects remain important for the interface between rough surfaces, which may include many small scale contacts of varying sizes. The results suggest that these effects may be significant in some cases, while insignificant for others. It depends on the load and the multiscale structure of the surface roughness.
Effect of geometry and composition on the intraband transitions of holes in quantum dots
Singh, Satish Kumar Kumar, Jitendra
2014-12-28
The effect of shape and size anisotropy on unipolar intraband transitions of holes in quantum dots (QDs) is studied. The optical matrix elements are calculated for transitions of holes in valence band. To get the optical matrix elements, energy eigenvalues and eigenvectors are calculated using 4?×?4 Luttinger Hamiltonian in the effective mass approximation. The formulation is applied to InGaAs/GaAs QD with parabolic confinement potential in xy-plane. The optical matrix elements for intraband hole transitions are calculated for x and y polarised light. The transitions are considered from ground state to other excited states. The effect of In concentration on optical matrix elements is also investigated. It is important to note that the transitions of holes are governed by the character of initial and final states for different light polarisations that give specific transition selection rules. It is found that the polarisation is strongly dependent on the in-plane anisotropy of the QDs.
Spin hall effect in paramagnetic thin films
Xu, Huachun
2009-05-15
ferromagnet rod as a spin injector. Process description and various techniques to improve the measurement sensitivity are presented. Measurement results in aluminum, gold and copper are presented in Chapters III, IV and V. Some new experiments are suggested...
On the dual topological quantum numbers filling factors
Wellington da Cruz
2003-05-26
We consider recent experimental results [W. Pan {\\it et al}, Phys. Rev. Lett. {\\bf 90}, 016801 (2003)] for occurrence of the fractional quantum Hall effect-FQHE under the perspective of our formulation in terms of {\\it fractons}. These objects carry rational or irrational values of spin and satisfy a {\\it fractal distribution function} associated with a {\\it fractal von Neumann entropy}. According to our approach the {\\it FQHE occurs in pairs of dual topological quantum numbers fillings factors} and this geometrical character comes from the {\\it connection betwenn the fractal parameter or Hausdorff dimension $h$ and the spin $s$ of the particles}. We suggest to the experimentalists consider our ideas and verify in fact that this phenomenon of FQHE satisfy a {\\it symmetry principle} discovered by us, i.e, {\\it the duality symmetry betwenn universal classes of fractons}.
Steric, Quantum, and Electrostatic Effects on S{sub N}2 Reaction Barriers in Gas Phase
Liu, Shubin; Hu, Hao; Pedersen, Lee G.
2010-05-13
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.
Minnesota, University of
1 Hybrid Quantum and Classical Methods for Computing Kinetic Isotope Effects of Chemical Reactions for computing kinetic isotope effects for chemical reactions in solution and in enzymes. In the ensemble that enzymes accelerate the rates of chemical reactions has fascinated chemists and biochemists for nearly
Theoretical analysis on quantum interference effect in fast-light media
Xu, Datang; Huang, Guoxiang
2015-01-01
We make a systematic theoretical analysis on the quantum interference (QI) effects in various fast-light media (including gain-assisted $N$, gain-assisted ladder-I, and gain-assisted ladder-II atomic systems). We show that such fast-light media are capable of not only completely eliminating the absorption but also suppressing the gain of signal field, and hence provide the possibility to realize a stable propagation of the signal field with a superluminal velocity. We find that there is a destructive (constructive) QI effect in gain-assisted ladder-I (gain-assisted N) system, but no QI in the gain-assisted ladder-II system; furthermore, a crossover from destructive (constructive) QI to Autler-Townes splitting may occur for the gain-assisted ladder-I (gain-assisted N) system when the control field of the system is modulated. Our theoretical analysis can be applied to other multi-level systems, and the results obtained may have promising applications in optical and quantum information processing and transmissio...
Quantum path-integral study of the phase diagram and isotope effects of neon
Ramirez, R; 10.1063/1.3023036
2011-01-01
The phase diagram of natural neon has been calculated for temperatures in the range 17-50 K and pressures between 0.01 and 2000 bar. The phase coexistence between solid, liquid, and gas phases has been determined by the calculation of the separate free energy of each phase as a function of temperature. Thus, for a given pressure, the coexistence temperature was obtained by the condition of equal free energy of coexisting phases. The free energy was calculated by using non-equilibrium techniques such as adiabatic switching and reversible scaling. The phase diagram obtained by classical Monte Carlo simulations has been compared to that obtained by quantum path-integral simulations. Quantum effects related to the finite mass of neon cause that coexistence lines are shifted towards lower temperatures when compared to the classical limit. The shift found in the triple point amounts to 1.5 K, i.e., about 6 % of the triple-point temperature. The triple-point isotope effect has been determined for 20Ne, 21Ne, 22Ne, a...
New York Hall of Science Connections: The Nature of Networks
Short, Daniel
New York Hall of Science Connections: The Nature of Networks (NSF Award No. 0229268) suzzo of Technology New York Hall of Science Flushing Meadows Corona Park, New York suzzo@nyscience.org +1
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New #12;The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New York, NY 10065 www
Semi-analytical model of ionization oscillations in Hall thrusters
Mockelman, Jeffrey A. (Jeffrey Alan)
2015-01-01
This thesis presents efforts to better understand the breathing-mode oscillation within Hall thrusters. These oscillations have been present and accepted within Hall thrusters for decades, but recent interest in the ...
Microwave generation by spin Hall nanooscillators with nanopatterned spin injector
Zholud, A., E-mail: azholud@emory.edu; Urazhdin, S. [Department of Physics, Emory University, Atlanta, Georgia 30322 (United States)
2014-09-15
We experimentally study spin Hall nano-oscillators based on Pt/ferromagnet bilayers with nanopatterned Pt spin injection layer. We demonstrate that both the spectral characteristics and the electrical current requirements can be simultaneously improved by reducing the spin injection area. Moreover, devices with nanopatterned Pt spin injector exhibit microwave generation over a wide temperature range that extends to room temperature. Studies of devices with additional Pt spacers under the device electrodes show that the oscillation characteristics are affected not only by the spin injection geometry but also by the effects of Pt/ferromagnet interface on the dynamical properties of the ferromagnet.
Spring 2015 Henderson Hall Education and Career Fair
Office of Energy Efficiency and Renewable Energy (EERE)
Location: Smith Gym, Henderson Hall, Arlington, VAPOC: DOECorporateRecruitment@hq.doe.govWebsite: http://bit.ly/1FRIJOF
Onset of fast reconnection in Hall magnetohydrodynamics mediated by the plasmoid instability
Huang Yimin; Bhattacharjee, A.; Sullivan, Brian P.
2011-07-15
The role of a super-Alfvenic plasmoid instability in the onset of fast reconnection is studied by means of the largest Hall magnetohydrodynamics simulations to date, with system sizes up to 10{sup 4} ion skin depths (d{sub i}). It is demonstrated that the plasmoid instability can facilitate the onset of rapid Hall reconnection, in a regime where the onset would otherwise be inaccessible because the Sweet-Parker width is significantly above d{sub i}. However, the topology of Hall reconnection is not inevitably a single stable X-point. There exists an intermediate regime where the single X-point topology itself exhibits instability, causing the system to alternate between a single X-point geometry and an extended current sheet with multiple X-points produced by the plasmoid instability. Through a series of simulations with various system sizes relative to d{sub i}, it is shown that system size affects the accessibility of the intermediate regime. The larger the system size is, the easier it is to realize the intermediate regime. Although our Hall magnetohydrodynamics (MHD) model lacks many important physical effects included in fully kinetic models, the fact that a single X-point geometry is not inevitable raises the interesting possibility for the first time that Hall MHD simulations may have the potential to realize reconnection with geometrical features similar to those seen in fully kinetic simulations, namely, extended current sheets and plasmoid formation.
Martin--Luther--Universit at Halle--Wittenberg
Liebenow, N. H. Cong, R. Weiner and K. Strehmel Report No. 41 (1997) Reports of the Institute of Numericaldimensional parabolic differential equations C. EichlerLiebenow, N. H. Cong, R. Weiner and K. Strehmel Report No. 41@mail.mathematik.unihalle.de rw@mathematik.unihalle.de strehmel@mathematik.unihalle.de Prof. Dr. N. H. Cong Faculty
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
Exponential Decay and Fermi's Golden Rule from an Uncontrolled Quantum Zeno Effect
P. W. Bryant
2014-10-14
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.
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
2014-01-01
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.
InP quantum dots: Electronic structure, surface effects, and the redshifted emission
Fu, H.; Zunger, A.
1997-07-01
We present pseudopotential plane-wave electronic-structure calculations on InP quantum dots in an effort to understand quantum confinement and surface effects and to identify the origin of the long-lived and redshifted luminescence. We find that (i) unlike the case in small GaAs dots, the lowest unoccupied state of InP dots is the {Gamma}{sub 1c}-derived direct state rather than the X{sub 1c}-derived indirect state and (ii) unlike the prediction of {bold k}{center_dot}{bold p} models, the highest occupied state in InP dots has a 1sd-type envelope function rather than a (dipole-forbidden) 1pf envelope function. Thus explanations (i) and (ii) to the long-lived redshifted emission in terms of an orbitally forbidden character can be excluded. Furthermore, (iii) fully passivated InP dots have no surface states in the gap. However, (iv) removal of the anion-site passivation leads to a P dangling bond (DB) state just above the valence band, which will act as a trap for photogenerated holes. Similarly, (v) removal of the cation-site passivation leads to an In dangling-bond state below the conduction band. While the energy of the In DB state depends only weakly on quantum size, its radiative lifetime increases with quantum size. The calculated {approximately}300-meV redshift and the {approximately}18 times longer radiative lifetime relative to the dot-interior transition for the 26-{Angstrom} dot with an In DB are in good agreement with the observations of full-luminescence experiments for unetched InP dots. Yet, (vi) this type of redshift due to surface defect is inconsistent with that measured in {ital selective} excitation for HF-etched InP dots. (vii) The latter type of ({open_quotes}resonant{close_quotes}) redshift is compatible with the calculated {ital screened} singlet-triplet splitting in InP dots, suggesting that the slow emitting state seen in selective excitation could be a triplet state. {copyright} {ital 1997} {ital The American Physical Society}
When is a quantum heat engine quantum?
Alexander Friedenberger; Eric Lutz
2015-08-17
Quantum thermodynamics studies quantum effects in thermal machines. But when is a heat engine, which cyclically interacts with external reservoirs that unavoidably destroy its quantum coherence, really quantum? We here use the Leggett-Garg inequality to assess the nonclassical properties of a single two-level Otto engine. We provide the complete phase diagram characterizing the quantumness of the engine as a function of its parameters and identify three distinct phases. We further derive an explicit expression for the transition temperature.
Effective Landé factor in a GaMnAs quantum dot; with the effects of sp-d exchange on a bound polaron
Lalitha, D., E-mail: a.john.peter@gmail.com; Peter, A. John, E-mail: a.john.peter@gmail.com [Dept. of Physics, Government Arts College, Melur-625106, Tamilnadu (India)
2014-04-24
The effective g-factor of conduction (valence) band electron (hole) is obtained in the GaMnAs quantum dot. Magneto bound polaron in a GaMnAs/Ga{sub 0.6}Al{sub 0.4}As quantum dot is investigated with the inclusion of exchange interaction effects due to Mn alloy content and the geometrical confinement. The spin polaronic energy of the heavy hole exciton is studied with the spatial confinement using a mean field theory in the presence of magnetic field strength.
http: www. wuli. ac. cn / 38 (2009~OE) 6 Graphene~ -- ... ^
Gao, Hongjun
and spintronics. Keywords¡¡ ¡¡ Graphene, quantum Hall effect, spintronics, devices 3 ... (¯oe..."¯ : 60771037
, such as the study of superconductivity and the fractional quantum hall effect, are devoted to understanding
Noncontact semiconductor wafer characterization with the terahertz Hall D. M. Mittleman,a)
Natelson, Douglas
of Physics. S0003-6951 97 01427-7 Doped semiconductors are frequently characterized by two material properties and quality. They also determine many of the electrical and optical properties of the material. NNoncontact semiconductor wafer characterization with the terahertz Hall effect D. M. Mittleman,a) J
Analysis of geometric phase effects in the quantum-classical Liouville formalism
Ryabinkin, Ilya G.; Izmaylov, Artur F.; Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6 ; Hsieh, Chang-Yu; Kapral, Raymond
2014-02-28
We analyze two approaches to the quantum-classical Liouville (QCL) formalism that differ in the order of two operations: Wigner transformation and projection onto adiabatic electronic states. The analysis is carried out on a two-dimensional linear vibronic model where geometric phase (GP) effects arising from a conical intersection profoundly affect nuclear dynamics. We find that the Wigner-then-Adiabatic (WA) QCL approach captures GP effects, whereas the Adiabatic-then-Wigner (AW) QCL approach does not. Moreover, the Wigner transform in AW-QCL leads to an ill-defined Fourier transform of double-valued functions. The double-valued character of these functions stems from the nontrivial GP of adiabatic electronic states in the presence of a conical intersection. In contrast, WA-QCL avoids this issue by starting with the Wigner transform of single-valued quantities of the full problem. As a consequence, GP effects in WA-QCL can be associated with a dynamical term in the corresponding equation of motion. Since the WA-QCL approach uses solely the adiabatic potentials and non-adiabatic derivative couplings as an input, our results indicate that WA-QCL can capture GP effects in two-state crossing problems using first-principles electronic structure calculations without prior diabatization or introduction of explicit phase factors.
Casimir effect in the nonequilibrium steady state of a quantum spin chain
Gonzalez-Cabrera, D. L.; Racz, Z.
2010-05-15
We present a fully microscopics-based calculation of the Casimir effect in a nonequilibrium system, namely, an energy-flux-driven quantum XX chain. The force between the walls (transverse-field impurities) is calculated in a nonequilibrium steady state which is prepared by letting the system evolve from an initial state with the two halves of the chain prepared at equilibrium at different temperatures. The steady state emerging in the large-time limit is homogeneous but carries an energy flux. The Casimir force in this nonequilibrium state is calculated analytically in the limit when the transverse fields are small. We find that the the Casimir force range is reduced compared to the equilibrium case, and suggest that the reason for this is the reduction of fluctuations in the flux-carrying steady state.
Quantum Otto cycle with inner friction: finite-time and disorder effects
A. Alecce; F. Galve; N. Lo Gullo; L. Dell'Anna; F. Plastina; R. Zambrini
2015-07-13
The concept of inner friction, by which a quantum heat engine is unable to follow adiabatically its strokes and thus dissipates useful energy, is illustrated in an exact physical model where the working substance consists of an ensemble of misaligned spins interacting with a magnetic field and performing the Otto cycle. The effect of this static disorder under a finite-time cycle gives a new perspective of the concept of inner friction under realistic settings. We investigate the efficiency and power of this engine and relate its performance to the amount of friction from misalignment and to the temperature difference between heat baths. Finally we propose an alternative experimental implementation of the cycle where the spin is encoded in the degree of polarization of photons.
Old Main Library Shih-Liang Hall
Wu, Yih-Min
Library Shih-Liang Hall Computer and Information Networking Center Audio-Visual Educational Center College of Engineering Bldg. E.E. Bldg. No. 2 Graduate Institute of National Development Graduate. of Library and Information Science Depot. of Atmospheric Sciences Main Library Dept. of Physics Center
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
Geometrical Music Theory Rachel Wells Hall1
Hall, Rachel W.
Geometrical Music Theory Rachel Wells Hall1 Music theorists have frequently invoked geometry in modeling musical objects such as chords, rhythms, and scales; however, no unified geometric perspective has musical terms can be understood as expressing symmetries of n-dimensional space. Identifying-- "gluing
SPROUL HALL 1124 RIVERSIDE, CA 92521
SPROUL HALL 1124 RIVERSIDE, CA 92521 education.ucr.edu TEACHER EDUCATION SERVICES (951) 827 School of Education teacher preparation program. For application information please go to the website and view Teacher Education Admission requirements http://education.ucr.edu/tcadmissions.html *Multiple
Light Board Operation 208 Jordan Hall
Buechler, Steven
Light Board Operation 208 Jordan Hall Using the Light Board 1. Turn on the lights next to the entry door. 2. Turn on the Light Board lights (illustration 1). The light switch is on the west wall, slightly behind the computer cart's display. 3. Locate the lapel microphone (usually on top of the Light
U.S. WRESTLING FEDERATION HALL
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 CORDELL ATHLETIC CENTER BOONE PICKENS STADIUM ANIMAL SCIENCES AGRICULTURAL SCIENCES MATH N. SMITH HALL ALUMNI CENTER HOUSING - JPI PHASE 1 BUILDING 3 HOUSING - JPI PHASE 1 BUILDING 4 STUDENT UNION
Melnik, Roderick
Influence of electromechanical effects and wetting layers on band structures of AlN/GaN quantum In a series of recent papers we demonstrated that coupled electromechanical effects can lead to pronounced
Martinis, John M.
2013-01-01
PHYSICAL REVIEW A 88, 062329 (2013) Understanding the effects of leakage in superconducting quantum of leakage in a two-qubit superconducting stabilizer measurement circuit. We simulate the repeated ancilla is important for superconducting qubits not only because higher-energy states |2 ,|3 , . . . are present [4
Talukder, Muhammad Anisuzzaman
Effects of backward-propagating waves and lumped mirror losses on self-induced transparency Work to date on self-induced transparency modelocking in quantum cascade lasers QCLs has neglected that is long compared to round-trip time Trt is required in order to suppress continuous waves that may lead
Disorder and interactions in quantum Hall ferromagnets near nu=1.
Sinova, Jairo; MacDonald, AH; Girvin, SM.
2000-01-01
Message Passing Interface (MPI) is a standard library interface for writing parallel programs. The MPI specification is broadly used for solving engineering and scientific problems on parallel computers, and MPICH2 is a ...
Scaling in the quantum Hall regime of graphene Corbino devices
Peters, Eva C.; Burghard, Marko [Max-Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Giesbers, A. J. M. [Max-Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Molecular Materials and Nanosystems, Eindhoven University of Technology, NL-5600 MB Eindhoven (Netherlands); Kern, Klaus [Max-Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Institut de Physique de la Matière Condensée, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland)
2014-05-19
The scaling behavior of graphene devices in Corbino geometry was investigated through temperature dependent conductivity measurements under magnetic field. Evaluation of the Landau level width as a function of temperature yielded a relatively low temperature exponent of ??=?0.16?±?0.05. Furthermore, an unusually large value close to 7.6?±?0.9 was found for the universal scaling constant ?, while the determined inelastic scattering exponent of p?=?2 is consistent with established scattering mechanisms in graphene. The deviation of the scaling parameters from values characteristic of conventional two-dimensional electron gases is attributed to an inhomogeneous charge carrier distribution in the Corbino devices. Direct evidence for the presence of the latter could be gained by spatially resolved photocurrent microscopy away from the charge neutrality point of the devices.
Topological Hubbard Model and Its High-Temperature Quantum Hall...
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Sponsoring Org: USDOE Country of Publication: United States Language: English Word Cloud More Like This Free Publicly Accessible Full Text Publisher's Accepted Manuscript at...
J. Wurm; K. Richter; I. Adagideli
2011-11-14
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.
Global Hall-MHD simulations of magnetorotational instability in a plasma Couette flow experiment
Ebrahimi, F.; Lefebvre, B.; Bhattacharjee, A.; Forest, C. B.
2011-06-15
Global MHD and Hall-MHD numerical simulations relevant to the Madison plasma Couette flow experiment (MPCX) have been performed using the extended MHD code NIMROD. The MPCX has been constructed to study the magnetorotational instability (MRI) in a plasma. The two-fluid Hall effect, which is relevant to some astrophysical situations such as protostellar disks, is also expected to be important in the MPCX. Here, we first derive the local Hall dispersion relation including viscosity, extending earlier work by Balbus and Terquem [Astrophys. J. 552, 235 (2001)]. The predictions of the local analysis are then compared with nonlocal calculations of linear stability of the MRI for a parameter range relevant to the MPCX. It is found that the MHD stability limit and mode structure are altered by the Hall term, and nonlocal analysis is necessary to obtain quantitatively reliable predictions for MPCX. Two-fluid physics also significantly changes the nonlinear evolution and saturation of the axisymmetric MRI. Both the Reynolds and Maxwell stresses contribute significantly to momentum transport. In the Hall regime, when the magnetic field is parallel to the rotation axis, the Maxwell stress is larger than the Reynolds stress (similar to the MHD regime). However, when the magnetic field is antiparallel to the rotation axis in the Hall regime, the Reynolds stress is much larger than the Maxwell stress. To further study the role of non-axisymmetric modes, we have also carried out fully nonlinear MHD computations. Non-axisymmetric modes play an increasingly important role as the magnetic Reynolds number increases and grow to large amplitudes in a saturated turbulent state.
Jussi Ilmari Lindgren
2013-02-13
This paper defines an equation for causality. This equation is then combined with the postulates of quantum mechanics and mass-energy equivalence to produce a quantum mechanical telegrapher's equation and to reproduce the Schrodinger and Klein-Gordon equations. The incompressible Navier-Stokes equations and dynamic general equilibrium in economics (with an interpretation of a Nash equilibrium) are obtained when the equation of causality refers to itself, i.e. when the cause is its own effect. As it is shown that the Klein-Gordon equation is obtained by Wick rotating the cause vector with de Broglie angular frequency, this paper postulates an equation for Quantum Gravity, which relates the Navier-Stokes equations to the Einstein Field Equations of General Relativity.
Local Availability of mathematics and number scaling: Effects on quantum physics
Paul Benioff
2012-05-01
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.
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)
2014-07-15
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.
2014-05-15
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)
CONTROL OF NON-RESONANT EFFECTS IN A NUCLERA SPIN QUANTUM COMPUTER...
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COMPUTER WITH A LARGE NUMBER OF QUBITS G. BERMAN; ET AL 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 99 GENERAL AND MISCELLANEOUSMATHEMATICS, COMPUTING, AND...
Electrical and Optical Gain Lever Effects in InGaAs Double Quantum Well Diode Lasers
Pocha, M D; Goddard, L L; Bond, T C; Nikolic, R J; Vernon, S P; Kallman, J S; Behymer, E M
2007-01-03
In multisection laser diodes, the amplitude or frequency modulation (AM or FM) efficiency can be improved using the gain lever effect. To study gain lever, InGaAs double quantum well (DQW) edge emitting lasers have been fabricated with integrated passive waveguides and dual sections providing a range of split ratios from 1:1 to 9:1. Both the electrical and the optical gain lever have been examined. An electrical gain lever with greater than 7 dB enhancement of AM efficiency was achieved within the range of appropriate DC biasing currents, but this gain dropped rapidly outside this range. We observed a 4 dB gain in the optical AM efficiency under non-ideal biasing conditions. This value agreed with the measured gain for the electrical AM efficiency under similar conditions. We also examined the gain lever effect under large signal modulation for digital logic switching applications. To get a useful gain lever for optical gain quenched logic, a long control section is needed to preserve the gain lever strength and a long interaction length between the input optical signal and the lasing field of the diode must be provided. The gain lever parameter space has been fully characterized and validated against numerical simulations of a semi-3D hybrid beam propagation method (BPM) model for the coupled electron-photon rate equation. We find that the optical gain lever can be treated using the electrical injection model, once the absorption in the sample is known.
Sai Vinjanampathy; Janet Anders
2015-08-25
Quantum thermodynamics is an emerging research field aiming to extend standard thermodynamics and non-equilibrium statistical physics to ensembles of sizes well below the thermodynamic limit, in non-equilibrium situations, and with the full inclusion of quantum effects. Fuelled by experimental advances and the potential of future nanoscale applications this research effort is pursued by scientists with different backgrounds, including statistical physics, many-body theory, mesoscopic physics and quantum information theory, who bring various tools and methods to the field. A multitude of theoretical questions are being addressed ranging from issues of thermalisation of quantum systems and various definitions of "work", to the efficiency and power of quantum engines. This overview provides a perspective on a selection of these current trends accessible to postgraduate students and researchers alike.
Fast Camera Imaging of Hall Thruster Ignition
C.L. Ellison, Y. Raitses and N.J. Fisch
2011-02-24
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
Peleshchak, R. M.; Guba, S. K.; Kuzyk, O. V.; Kurilo, I. V.; Dankiv, O. O.
2013-03-15
The distribution of hydrostatic strains in Bi{sup 3+}-doped InAs quantum dots embedded in a GaAs matrix are calculated in the context of the deformation-potential model. The dependences of strains in the material of spherical InAs quantum dots with substitutional (Bi {yields} As) and interstitial (Bi) impurities on the quantum-dot size are derived. The qualitative correlation of the model with the experiment is discussed. The data on the effect of doping on the morphology of self-assembled InAs:Bi quantum dots in a GaAs matrix are obtained.
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)
2006-10-15
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.
Quantum oscillations as a probe of interaction effects in Weyl semimetals in a magnetic field
E. V. Gorbar; V. A. Miransky; I. A. Shovkovy; P. O. Sukhachov
2014-09-18
The Weyl semimetal surface is modeled by applying the Bogolyubov boundary conditions, in which the quasiparticles have an infinite Dirac mass outside the semimetal. For a Weyl semimetal shaped as a slab of finite thickness, we derive an exact spectral equation for the quasiparticle states and obtain the spectrum of the bulk as well as surface Fermi arc modes. We also show that, in the presence of the magnetic field, the separation between Weyl nodes in momentum space and the length of the Fermi arcs in the reciprocal space are affected by the interactions. As a result, we find that the period of oscillations of the density of states related to closed magnetic orbits involving Fermi arcs has a nontrivial dependence on the orientation of the magnetic field projection in the plane of the semimetal surface. We conclude that the momentum space separation between Weyl nodes and its modification due the interaction effects in the magnetic field can be measured in the experimental studies of quantum oscillations.
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)
2014-07-14
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.
P. Kurian; C. Verzegnassi
2015-08-01
We consider in a quantum field theory framework the effects of a classical magnetic field on the spin and orbital angular momentum (OAM) of a free electron. We derive formulae for the changes in the spin and OAM due to the introduction of a general classical background field. We consider then a constant magnetic field, in which case the relevant expressions of the effects become much simpler and conversions between spin and OAM become readily apparent. An estimate of the expectation values for a realistic electron state is also given. Our findings may be of interest to researchers in spintronics and the field of quantum biology, where electron spin has been implicated on macroscopic time and energy scales.
CRIMINAL OFFENSES ON CAMPUS RESIDENTIAL HALL NONCAMPUS PUBLIC
Elzanowski, Marek
CRIMINAL OFFENSES ON CAMPUS ON CAMPUS RESIDENTIAL HALL NONCAMPUS PUBLIC Murder & Non, Sexual Orientation, Gender, Gender Identity, Disability, Ethnicity, National Origin) Murder & Non
Building America Top Innovations Hall of Fame Profile - Building...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Building America Top Innovations Hall of Fame Profile - Building America's Top Innovations Propel the Home Building Industry toward Higher Performance Building America Top...
Building America Top Innovations Hall of Fame Profile ? Integration...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
are essential to realizing the promise of high-performance homes. BUILDING AMERICA TOP INNOVATIONS HALL OF FAME PROFILE INNOVATIONS CATEGORY: 1. Advanced Technologies and...
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New Technology Transfer (212) 327-7095 tsuprapto@rockefeller.edu #12;
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New Director Technology Transfer (212) 327-7095 tsuprapto@rockefeller.edu #12;
Rebuilding It Better: Greensburg, Kansas, City Hall (Brochure)
Not Available
2010-09-01
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.
Rebuilding It Better: Greensburg, Kansas. City Hall (Brochure)
Not Available
2010-04-01
This document showcases the LEED-Platinum designed Greensburg City Hall, which was rebuilt green, after a massive tornado destroyed Greensburg, Kansas in May 2007.
Schedule and cost estimate for an innovative Boston Harbor concert hall
Coste, Amelie, 1982-
2004-01-01
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 ...
Sinitsyn, NA; Hankiewicz, EM; Teizer, Winfried; Sinova, Jairo.
2004-01-01
-split subbands being occupied.8 Motivated by re- cent experiments12,13 which have demonstrated the ability to tune the magnitude of the Rashba and Dresselhaus spin-orbit coupling strength directly and by the fact that when both coupling strengths are equal... Hall effect accounts rather convincingly for experimental observations.36 Besides the several approaches already proposed to mea- sure the spin-Hall effect,7,8,12,37 the tunability of both the Rashba and Dresselhaus coupling parameters12,13...
Effect of swift heavy ion irradiation on bare and coated ZnS quantum dots
Chowdhury, S. Hussain, A.M.P.; Ahmed, G.A.; Singh, F.; Avasthi, D.K.; Choudhury, A.
2008-12-01
The present study compares structural and optical modifications of bare and silica (SiO{sub 2}) coated ZnS quantum dots under swift heavy ion (SHI) irradiation. Bare and silica coated ZnS quantum dots were prepared following an inexpensive chemical route using polyvinyl alcohol (PVA) as the dielectric host matrix. X-ray diffraction (XRD) and transmission electron microscopy (TEM) study of the samples show the formation of almost spherical ZnS quantum dots. The UV-Vis absorption spectra reveal blue shift relative to bulk material in absorption energy while photoluminescence (PL) spectra suggests that surface state and near band edge emissions are dominating in case of bare and coated samples, respectively. Swift heavy ion irradiation of the samples was carried out with 160 MeV Ni{sup 12+} ion beam with fluences 10{sup 12} to 10{sup 13} ions/cm{sup 2}. Size enhancement of bare quantum dots after irradiation has been indicated in XRD and TEM analysis of the samples which has also been supported by optical absorption spectra. However similar investigations on irradiated coated quantum dots revealed little change in quantum dot size and emission. The present study thus shows that the coated ZnS quantum dots are stable upon SHI irradiation compared to the bare one.
Interpretation of cosmological expansion effects on the quantum-classical transition
C. L. Herzenberg
2006-06-07
Recently, what appears to be a fundamental limit associated with the size of an object that separates the quantum behavior characterizing small objects from the classical behavior characterizing large objects has been derived from the Hubble velocity spread in an extended object. This threshold is now examined further and interpreted in terms of diffusion processes in stochastic quantum mechanics. This limiting size that separates quantum behavior from classical behavior is shown to correspond approximately to the diffusion distance of the object over the Hubble time.
Ye, Peng
2015-01-01
Topological quantum field theory (TQFT) plays a very important role in understanding topological phases of quantum matter. For example, Chern-Simons theory reveals the key mechanism of charge-flux attachment for fractional quantum hall effect (FQHE). It also completely describes all the essential topological data, e.g., fractionalized statistics, fractionalized charge of quasiparticles in FQHE sytems. Very recently, a new class of topological phases -- symmetry-protected topological (SPT) phases in interacting bosonic systems has been proposed based on the (extended) group cohomology theory. In two dimensions, it has been shown that bosonic SPT phases with Abelian symmetry can be well understood in terms of Chern-Simons theory. In this paper, we attempt to achieve a complete TQFT description for all bosonic SPT phases with Abelian group symmetry in three dimensions. The TQFT description reveals the key mechanism for three dimensional bosonic SPT phases in a simple and intuitive way.
Spin-Hall-assisted magnetic random access memory
Brink, A. van den, E-mail: a.v.d.brink@tue.nl; Swagten, H. J. M.; Koopmans, B. [Physics of Nanostructures, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands)] [Physics of Nanostructures, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Cosemans, S.; Manfrini, M.; Van Roy, W.; Min, T. [imec, Kapeldreef 75, B-3001 Leuven (Belgium)] [imec, Kapeldreef 75, B-3001 Leuven (Belgium); Cornelissen, S.; Vaysset, A. [imec, Kapeldreef 75, B-3001 Leuven (Belgium) [imec, Kapeldreef 75, B-3001 Leuven (Belgium); Departement elektrotechniek (ESAT), KU Leuven, Kasteelpark Arenberg 10, B-3001 Heverlee (Belgium)
2014-01-06
We propose a write scheme for perpendicular spin-transfer torque magnetoresistive random-access memory that significantly reduces the required tunnel current density and write energy. A sub-nanosecond in-plane polarized spin current pulse is generated using the spin-Hall effect, disturbing the stable magnetic state. Subsequent switching using out-of-plane polarized spin current becomes highly efficient. Through evaluation of the Landau-Lifshitz-Gilbert equation, we quantitatively assess the viability of this write scheme for a wide range of system parameters. A typical example shows an eight-fold reduction in tunnel current density, corresponding to a fifty-fold reduction in write energy, while maintaining a 1?ns write time.
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 noise and radiation pressure effects in high power optical interferometers
Corbitt, Thomas Randall
2008-01-01
In recent years, a variety of mechanical systems have been approaching quantum limits to their sensitivity of continuous position measurements imposed by the Heisenberg Uncertainty Principle. Most notably, gravitational ...
Sariyanni, Zoe-Elizabeth
2006-10-30
In the present quantum optics and laser physics study, the non-linear interaction of electromagnetic fields with atomic, molecular and biomolecular media is analyzed. Particular emphasis is given to coherent phenomena, while propagation...
Impact of uniaxial strain on P-channel 111-V quantum-well field effect transistors
Xia, Ling, Ph. D. Massachusetts Institute of Technology
2012-01-01
Continuous scaling of Si complementary metal-oxide-semiconductor (CMOS) technology requires a boost in carrier injection velocity. With the benefits of strained Si having been exhausted, n-channel I-V quantum-well field ...
Dynamics of quantum-classical hybrid systems: Effect of matter-wave pressure
Shen, J. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Huang, X. L. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); School of Physics and Electronic Technology, Liaoning Normal University, Dalian 116029 (China); Yi, X. X. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Centre for Quantum Technologies and Department of Physics, National University of Singapore, Singapore 117543 (Singapore); Wu Chunfeng; Oh, C. H. [Centre for Quantum Technologies and Department of Physics, National University of Singapore, Singapore 117543 (Singapore)
2010-12-15
Radiation pressure affects the kinetics of a system exposed to radiation and it constitutes the basis of laser cooling. In this article, we study matter-wave pressure through examining the dynamics of a quantum-classical hybrid system. The quantum and classical subsystems are affected mutually via a changing boundary condition. Two systems, that is, an atom and a Bose-Einstein condensate (BEC), are considered as the quantum subsystems, while an oscillating wall is taken as the classical subsystem. We show that the classical subsystem would experience a force proportional to Q{sup -3} from the quantum atom, where Q denotes the distance between the two walls, whereas it acquires an additional force proportional to Q{sup -2} from the BEC due to the atom-atom interaction in the BEC. These forces can be understood as the matter-wave pressure.
The effect of quantum correction on plasma electron heating in ultraviolet laser interaction
Zare, S.; Sadighi-Bonabi, R. Anvari, A.; Yazdani, E.; Hora, H.
2015-04-14
The interaction of the sub-picosecond UV laser in sub-relativistic intensities with deuterium is investigated. At high plasma temperatures, based on the quantum correction in the collision frequency, the electron heating and the ion block generation in plasma are studied. It is found that due to the quantum correction, the electron heating increases considerably and the electron temperature uniformly reaches up to the maximum value of 4.91?×?10{sup 7?}K. Considering the quantum correction, the electron temperature at the laser initial coupling stage is improved more than 66.55% of the amount achieved in the classical model. As a consequence, by the modified collision frequency, the ion block is accelerated quicker with higher maximum velocity in comparison with the one by the classical collision frequency. This study proves the necessity of considering a quantum mechanical correction in the collision frequency at high plasma temperatures.
Valley pair qubits in double quantum dots of gapped graphene
G. Y. Wu; N. -Y. Lue; L. Chang
2011-07-03
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)).
Singh, Jaswinder Pal
Prince April 2 Alumn ertson Hall vent is open a.m. a.m. a.m. a.m. a.m. a.m. p.m. p.m. ww.createsu or informatio //www.princ Princ eton Pr 24-25, 201 ni and Com Saturday 8:00 a.m , Dodds Au n to the pub Alumnia sity Â· Prince ram stein Galler for meals. yBreakfas marks PrizeWin PrizeWin ceinthe einaRacia orof
Hall of Honor 2014: Pursuing Explanations, Discovering Robert Brooks
Hall of Honor 2014: Pursuing Explanations, Discovering Ourselves Foundry Robert Brooks Mon, 2014, but there is something more about his experience that earns his recognition in the Foundry Management & Technology Hall at the Department of Materials Science and Engineering at Virginia Tech; Director of VT-FIRE (Foundry Institute
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
An edition of Hall Caine's The Demon Lover
Linnstaedter, Joan
1993-01-01
Hall Caine, once a popular writer, is now forgotten. This is the first edition of Hall Caine's play The Demon Lover. The text is based on the only known typescript of the play which is corrected in the author's own hand and which was bound...
143 Caldwell Hall Ithaca, NY 14853-2602
Chen, Tsuhan
with the Graduate School Student Services Records Team, Room 143 Caldwell Hall, or see the Code online at www the original copy with Graduate School Student Services Records Team, Room 143 Caldwell Hall. When an action in New York City, and the Weill Cornell Graduate School of Medical Sciences in New York City. These five
Pair spectrometer hodoscope for Hall D at Jefferson Lab
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Barbosa, Fernando J.; Hutton, Charles L.; Sitnikov, Alexandre; Somov, Alexander S.; Somov, S.; Tolstukhin, Ivan
2015-09-21
We present the design of the pair spectrometer hodoscope fabricated at Jefferson Lab and installed in the experimental Hall D. The hodoscope consists of thin scintillator tiles; the light from each tile is collected using wave-length shifting fibers and detected using a Hamamatsu silicon photomultiplier. Light collection was measured using relativistic electrons produced in the tagger area of the experimental Hall B.
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New.D. Assistant Director Technology Transfer (212) 327-7095 tsuprapto@rockefeller.edu #12;The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New York, NY 10065 www
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New.D. Assistant Director Technology Transfer (212) 327-7095 tsuprapto@rockefeller.edu #12;The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New York, NY 10021-6399 www
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New.1217207109 Tari Suprapto, Ph.D. Assistant Director Technology Transfer (212) 327-7095 tsuprapto@rockefeller.edu #12;The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New:1484-1488. #12;The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New York, NY 10021-6399 www.rockefeller.edu/techtransfer Tari Suprapto, Ph.D. Assistant Director Technology
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New Sabharwal, Ph.D. Technology Manager Office of Technology Transfer (212) 327-7092 nsabharwal@rockefeller.edu #12;The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New York, NY 10021-6399 www.rockefeller.edu/techtransfer Tari Suprapto, Ph.D. Assistant Director Technology Transfer (212) 327-7095 tsuprapto
Building Room Max Alderson Hall (AH) 134 49 Lecture
Building (BB) W210 63 Auditorium Brown Building (BB) W250 93 Auditorium Brown Building (BB) W280 130 Auditorium Brown Building (BB) W375 24 Lecture Coulbaugh Hall (CO) 131 50 Auditorium Coulbaugh Hall (CO) 209) 210N 123 Auditorium Green Center (GC) 210S 118 Auditorium Green Center (GC) 211 44 Lecture Green
University of Alberta Museums Curator Hall of Fame: Nomination Form
Machel, Hans
University of Alberta Museums Curator Hall of Fame: Nomination Form General Instructions: 1. Please someone other than the nominator 3. To be eligible for the University of Alberta Museums' Curator Hall of service in the role as Designated Curator of one of the registered University of Alberta Museums
RCP Spring 2011 SPONSORS MEETING PETROLEUM HALL, GREEN CENTER
RCP Spring 2011 SPONSORS MEETING PETROLEUM HALL, GREEN CENTER Colorado School of Mines 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
Low-frequency azimuthal stability analysis of Hall Diego Escobar
Carlos III de Madrid, Universidad
-neutral collision frequency w, we particle and energy wall-loss frequencies i energy loss per actual ionization i,e ion and electron cyclotron Larmor frequencies frequency of perturbation k azimuthal wave number and development of Hall thrusters. Nowadays, there are several companies manufacturing modern Hall thrusters
Nonequilibrium thermal effects on exciton time correlations in coupled semiconductor quantum dots
Castillo, J. C.; Rodríguez, F. J.; Quiroga, L.
2013-12-04
Theoretical guides to test 'macroscopic realism' in solid-state systems under quantum control are highly desirable. Here, we report on the evolution of a Leggett-Garg inequality (LGI), a combination of two-time correlations, in an out-of-equilibrium set up consisting of two interacting excitons confined in separate semiconductor quantum dots which are coupled to independent baths at different temperatures (T{sub 1} ? T{sub 2}). In a Markovian steady-state situation we found a rich variety of dynamical behaviors in different sectors of the average temperature (T{sub M}?=?(T{sub 1}+T{sub 2})/2) vs. coupling strength to the reservoirs (?) space parameter. For high T{sub M} and ? values the LGI is not violated, as expected. However, by decreasing T{sub M} or ? a sector of parameters appears where the LGI is violated at thermal equilibrium (T{sub 1} = T{sub 2}) and the violation starts decreasing when the system is moved out of the equilibrium. Surprisingly, at even lower T{sub M} values, for any ?, there is an enhancement of the LGI violation by exposing the system to a temperature gradient, i.e. quantum correlations increase in a nonequilibrium thermal situation. Results on LGI violations in a steady-state regime are compared with other non-locality-dominated quantum correlation measurements, such as concurrence and quantum discord, between the two excitons under similar temperature gradients.
Quantum Evolution and Anticipation
Hans-Rudolf Thomann
2010-03-04
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.
Undulator Hall Air Temperature Fault Scenarios
Sevilla, J.; Welch, J.; ,
2010-11-17
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.
2010-10-18
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. __________________________________________________
Observables on Quantum Structures
Anatolij Dvure?enskij; Mária Kuková
2012-04-29
An observable on a quantum structure is any $\\sigma$-homomorphism of quantum structures from the Borel $\\sigma$-algebra into the quantum structure. We show that our partial information on an observable known only for all intervals of the form $(-\\infty,t)$ is sufficient to determine uniquely the whole observable defined on quantum structures like $\\sigma$-MV-algebras, $\\sigma$-effect algebras, Boolean $\\sigma$-algebras, monotone $\\sigma$-complete effect algebras with the Riesz Decomposition Property, the effect algebra of effect operators of a Hilbert space, and a system of functions, and an effect-tribe.
Oshmyansky, A
2007-01-01
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
2007-03-08
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.
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
2015-06-16
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.
Quantum Physics and Nanotechnology
Vladimir K. Nevolin
2011-06-06
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.
Photophysics of dopamine-modified quantum dots and effects on biological
Minarik, William
between a small molecule (the neurotransmitter dopamine) and CdSe/ZnS QDs. QDdopamine conjugates label that has been studied extensively for the creation of solar cells and optoelectronic devices (see ref. 1 established with CdSe and CdSe/ZnS quantum dots (QDs)35 , its application to living systems has not yet been
Quantum corrections and bound-state effects in the energy relaxation of hot dense Hydrogen
Dharma-Wardana, M W C
2008-01-01
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.
Quantum corrections and bound-state effects in the energy relaxation of hot dense Hydrogen
M. W. C. Dharma-Wardana
2008-04-13
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.
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)
2011-03-15
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'.
Wang, Zhi [State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Jiang, Xiang-Wei; Li, Shu-Shen [State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wang, Lin-Wang, E-mail: lwwang@lbl.gov [Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
2014-03-24
We have presented a fully atomistic quantum mechanical simulation method on band-to-band tunneling (BTBT) field-effect transistors (FETs). Our simulation approach is based on the linear combination of bulk band method with empirical pseudopotentials, which is an atomist method beyond the effective-mass approximation or k.p perturbation method, and can be used to simulate real-size devices (?10{sup 5} atoms) efficiently (?5 h on a few computational cores). Using this approach, we studied the InAs dual-gate BTBT FETs. The I-V characteristics from our approach agree very well with the tight-binding non-equilibrium Green's function results, yet our method costs much less computationally. In addition, we have studied ways to increase the tunneling current and analyzed the effects of different mechanisms for that purpose.
Derivative expansion of the effective action for quantum electrodynamics in 2+1 and 3+1 dimensions
Gusynin, V.P.; Shovkovy, I.A.
1999-11-01
The derivative expansion of the one-loop effective action in QED{sub 3} and QED{sub 4} (quantum electrodynamics) is considered. The first term in such an expansion is the effective action for a constant electromagnetic field. An explicit expression for the next term containing two derivatives of the field strength F{sub {mu}{nu}}, but exact in the magnitude of the field strength, is obtained. The general results for both fermion and scalar electrodynamics are presented. The cases of pure electric and pure magnetic external fields are considered in detail. The Feynman technique for the perturbative expansion of the one-loop effective action in the number of derivatives is developed. {copyright} {ital 1999 American Institute of Physics.}
Alessandro Sergi
2009-07-11
A critical assessment of the recent developments of molecular biology is presented. The thesis that they do not lead to a conceptual understanding of life and biological systems is defended. Maturana and Varela's concept of autopoiesis is briefly sketched and its logical circularity avoided by postulating the existence of underlying {\\it living processes}, entailing amplification from the microscopic to the macroscopic scale, with increasing complexity in the passage from one scale to the other. Following such a line of thought, the currently accepted model of condensed matter, which is based on electrostatics and short-ranged forces, is criticized. It is suggested that the correct interpretation of quantum dispersion forces (van der Waals, hydrogen bonding, and so on) as quantum coherence effects hints at the necessity of including long-ranged forces (or mechanisms for them) in condensed matter theories of biological processes. Some quantum effects in biology are reviewed and quantum mechanics is acknowledged as conceptually important to biology since without it most (if not all) of the biological structures and signalling processes would not even exist. Moreover, it is suggested that long-range quantum coherent dynamics, including electron polarization, may be invoked to explain signal amplification process in biological systems in general.
Constructive Inversion of Energy Trajectories in Quantum Mechanics
Hall, Richard L.
page 1 Constructive Inversion of Energy Trajectories in Quantum Mechanics Richard L. Hall Department of Mathematics and Statistics, Concordia University, 1455 de Maisonneuve Boulevard West, MontrÂ´eal algorithm is devised which allows the potential shape f(x) to be reconstructed from the energy trajectory F
Quantum Chaos & Quantum Computers
D. L. Shepelyansky
2000-06-15
The standard generic quantum computer model is studied analytically and numerically and the border for emergence of quantum chaos, induced by imperfections and residual inter-qubit couplings, is determined. This phenomenon appears in an isolated quantum computer without any external decoherence. The onset of quantum chaos leads to quantum computer hardware melting, strong quantum entropy growth and destruction of computer operability. The time scales for development of quantum chaos and ergodicity are determined. In spite the fact that this phenomenon is rather dangerous for quantum computing it is shown that the quantum chaos border for inter-qubit coupling is exponentially larger than the energy level spacing between quantum computer eigenstates and drops only linearly with the number of qubits n. As a result the ideal multi-qubit structure of the computer remains rather robust against imperfections. This opens a broad parameter region for a possible realization of quantum computer. The obtained results are related to the recent studies of quantum chaos in such many-body systems as nuclei, complex atoms and molecules, finite Fermi systems and quantum spin glass shards which are also reviewed in the paper.
Effects of systematic phase errors on optimized quantum random-walk search algorithm
Yu-Chao Zhang; Wan-Su Bao; Xiang Wang; Xiang-Qun Fu
2015-01-09
This paper researches how the systematic errors in phase inversions affect the success rate and the number of iterations in optimized quantum random-walk search algorithm. Through geometric description of this algorithm, the model of the algorithm with phase errors is established and the relationship between the success rate of the algorithm, the database size, the number of iterations and the phase error is depicted. For a given sized database, we give both the maximum success rate of the algorithm and the required number of iterations when the algorithm is in the presence of phase errors. Through analysis and numerical simulations, it shows that optimized quantum random-walk search algorithm is more robust than Grover's algorithm.
K-quantum nonlinear coherent states: formulation, realization and nonclassical effects
Nguyen Ba An
2001-03-15
We introduce a generalized class of states called K-quantum nonlinear coherent states. Each K-state has K j-components corresponding to one and the same eigenvalue. Each Kj-component can be composed of K K=1-states in a correlated manner. The introduced states are shown to be realized in the long-term behavior of the vibrational motion of an ion properly trapped and laser-driven. Nonclassical properties of the states are studied in detail.
Davies, M. J. Dawson, P.; Massabuau, F. C.-P.; Oliver, R. A.; Kappers, M. J.; Humphreys, C. J.
2014-09-01
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.
DARTMOUTH COLLEGE CAMPUS PLANNING & FACILITIES 6111 McKenzie Hall
DARTMOUTH COLLEGE CAMPUS PLANNING & FACILITIES 6111 McKenzie Hall Hanover, New Hampshire 03755 to monitor conditions and help identify the problem. Electric heaters: Electric heaters may be temporarily
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...
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New Sabharwal, Ph.D. Technology Manager Office of Technology Transfer (212) 327-7092 nsabharwal
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New-technique-efficiently-turns-antibodies-into-highly- tuned-nanobodies/ Nidhi Sabharwal, Ph.D. Assistant Director Office of Technology Transfer (212) 327
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New(19):4355-4364 Nidhi Sabharwal, Ph.D. Technology Manager Office of Technology Transfer (212) 327-7092 nsabharwal
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New.1016/j.jmb.2008.01.066 Tari Suprapto, Ph.D. Assistant Director Technology Transfer (212) 327
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New11067 Cherise T. Bernard, Ph.D. Assistant Technology Manager Technology Transfer (212) 327-8263 cbernard
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New, Ph.D. Technology Manager Office of Technology Transfer (212) 327-7092 nsabharwal@rockefeller.edu #12;
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New,049,814 · US Patent 8,553,143 Nidhi Sabharwal, Ph.D. Technology Manager Technology Transfer (212) 327
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New.D. Assistant Director Technology Transfer (212) 327-7095 tsuprapto@rockefeller.edu #12;
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New, Ph.D. Assistant Director Technology Transfer (212) 327-7095 tsuprapto@rockefeller.edu #12;
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New and Chemotherapy, e-pub PMID:25605353 Tari Suprapto, Ph.D. Assistant Director Technology Transfer (212) 327
The Rockefeller University Office of Technology Transfer 502 Founders Hall
The Rockefeller University Office of Technology Transfer 502 Founders Hall 1230 York Avenue New,383,370. Tari Suprapto, Ph.D. Assistant Director Technology Transfer (212) 327-7095 tsuprapto
Directions to East Hall: I-94 (Ford Freeway)
Jonides, John
Directions to East Hall: I-94 (Ford Freeway) From Detroit and the Detroit Metropolitan on your right. I-96 (also called the Jeffries Freeway) From Parts of Detroit, Redford, M-14, Plymouth
Theoretical and experimental investigation of Hall thruster miniaturization
Warner, Noah Zachary, 1978-
2007-01-01
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 ...
Xavier Busch
2014-11-06
The two main predictions of quantum field theory in curved space-time, namely Hawking radiation and cosmological pair production, have not been directly tested and involve ultra high energy configurations. As a consequence, they should be considered with caution. Using the analogy with condensed matter systems, their analogue versions could be tested in the lab. Moreover, the high energy behavior of these systems is known and involves dispersion and dissipation, which regulate the theory at short distances. When considering experiments which aim to test the above predictions, there will also be a competition between the stimulated emission from thermal noise and the spontaneous emission out of vacuum. In order to measure these effects, one should thus compute the consequences of UV dispersion and dissipation, and identify observables able to establish that the spontaneous emission took place. In this thesis, we first analyze the effects of dispersion and dissipation on both Hawking radiation and pair particle production. To get explicit results, we work in the context of de Sitter space. Using the extended symmetries of the theory in such a background, exact results are obtained. These are then transposed to the context of black holes using the correspondence between de Sitter space and the black hole near horizon region. To introduce dissipation, we consider an exactly solvable model producing any decay rate. We also study the quantum entanglement of the particles so produced. In a second part, we consider explicit condensed matter systems, namely Bose Einstein condensates and exciton-polariton systems. We analyze the effects of dissipation on entanglement produced by the dynamical Casimir effect. As a final step, we study the entanglement of Hawking radiation in the presence of dispersion for a generic analogue system.
Scalable optical quantum computer
Manykin, E A; Mel'nichenko, E V [Institute for Superconductivity and Solid-State Physics, Russian Research Centre 'Kurchatov Institute', Moscow (Russian Federation)
2014-12-31
A way of designing a scalable optical quantum computer based on the photon echo effect is proposed. Individual rare earth ions Pr{sup 3+}, regularly located in the lattice of the orthosilicate (Y{sub 2}SiO{sub 5}) crystal, are suggested to be used as optical qubits. Operations with qubits are performed using coherent and incoherent laser pulses. The operation protocol includes both the method of measurement-based quantum computations and the technique of optical computations. Modern hybrid photon echo protocols, which provide a sufficient quantum efficiency when reading recorded states, are considered as most promising for quantum computations and communications. (quantum computer)
Raj Chakrabarti; Herschel Rabitz
2007-10-03
Numerous lines of experimental, numerical and analytical evidence indicate that it is surprisingly easy to locate optimal controls steering quantum dynamical systems to desired objectives. This has enabled the control of complex quantum systems despite the expense of solving the Schrodinger equation in simulations and the complicating effects of environmental decoherence in the laboratory. Recent work indicates that this simplicity originates in universal properties of the solution sets to quantum control problems that are fundamentally different from their classical counterparts. Here, we review studies that aim to systematically characterize these properties, enabling the classification of quantum control mechanisms and the design of globally efficient quantum control algorithms.
Eslami, Leila, E-mail: Leslami@iust.ac.ir; Esmaeilzadeh, Mahdi, E-mail: mahdi@iust.ac.ir [Department of Physics, Iran University of Science and Technology, Tehran 16846 (Iran, Islamic Republic of)
2014-02-28
Spin-dependent electron transport in an open double quantum ring, when each ring is made up of four quantum dots and threaded by a magnetic flux, is studied. Two independent and tunable gate voltages are applied to induce Rashba spin-orbit effect in the quantum rings. Using non-equilibrium Green's function formalism, we study the effects of electron-electron interaction on spin-dependent electron transport and show that although the electron-electron interaction induces an energy gap, it has no considerable effect when the bias voltage is sufficiently high. We also show that the double quantum ring can operate as a spin-filter for both spin up and spin down electrons. The spin-polarization of transmitted electrons can be tuned from ?1 (pure spin-down current) to +1 (pure spin-up current) by changing the magnetic flux and/or the gates voltage. Also, the double quantum ring can act as AND and NOR gates when the system parameters such as Rashba coefficient are properly adjusted.
Diffusion Compton profondement virtuelle dans le Hall A au Jefferson Laboratory
Carlos Munoz Camacho
2005-12-01
Generalized Parton Distributions (GPDs), introduced in the late 90s, provide a universal description of hadrons in terms of the underlying degrees of freedom of Quantum Chromodynamics: quarks and gluons. GPDs appear in a wide variety of hard exclusive reactions and the advent of high luminosity accelerator facilities has made the study of GPDs accessible to experiment. Deeply Virtual Compton Scattering (DVCS) is the golden process involving GPDs. The first dedicated DVCS experiment ran in the Hall A of Jefferson Lab in Fall 2004. An electromagnetic calorimeter and a plastic scintillator detector were constructed for this experiment, together with specific electronics and acquisition system. The experiment preparation, data taking and analysis are described in this document. Results on the absolute cross section difference for opposite beam helicities provide the first measurement of a linear combination of GPDs as a function of the momentum transfer to the nucleon.
Dynamics of Thermal Effects in the Spin-Wave Theory of Quantum Antiferromagnets
Ángel Rivas; Miguel A. Martin-Delgado
2013-01-17
We derive a master equation that allows us to study non-equilibrium dynamics of a quantum antiferromagnet. By resorting to spin-wave theory, we obtain a closed analytic form for the magnon decay rates. These turn out to be closely related to form factors, which are experimentally accessible by means of neutron and Raman scattering. Furthermore, we compute the time evolution of the staggered magnetization showing that, for moderate temperatures, the magnetic order is not spoiled even if the coupling is fully isotropic.
Shepelyansky, Dima
in quantum computation, including the simula- tion of quantum chaos models showing rich and complex dynamics and image compression, signal process- ing, telecommunications and many other applications [1, 2]. Wavelets
Bigham, S.R.; Coffer, J.L. [Texas Christian Univ., Fort Worth, TX (United States)
1993-12-31
Cadmium sulfide semiconductor clusters in the quantum confined size regime (Q-CdS) may be successfully stabilized by double-stranded deoxyribonucleic acid (DNA) from calf thymus and E. Coli as well as by single-stranded ribonucleic acids (RNA) in the forms of Poly[A], Poly[C], Poly[G] and Poly [U]. These Q-CdS/ploynucleotide clusters exhibit broad trap emission characteristic of both cadmium and sulfur related defect sites at the semiconductor surface. Here the paper discusses differences in the nature of the stabilizer-cluster interaction between single-stranded and double-stranded polynucleotides, as probed by monitoring changes in photoluminescence after thermolysis or ferrocyanide addition. Thermolysis of Q-CdS/polynucleotide samples affects the interfacial interaction between cluster and stabilizer as demonstrated by a shift in the emission maximum and a change in quantum yield. Stern-Volmer analysis of photoluminescence quenching with ferrocyanide anions exhibits nonlinear behavior. Ferrocyanide anions quench the photoluminescene of Q-CdS/DNA approximately 38% more efficiently (in terms of integrated intensity) than Q-CdS/RNA after 0.17 mN addition. Such behavior suggests that single-stranded polynucleotides are better than double-stranded polynucleotides in terms of protecting the semiconductor surface from the highly negatively charged ferrocyanide anion.
Superradiant Quantum Heat Engine
Ali Ü. C. Hardal; Özgür E. Müstecapl?oglu
2015-07-16
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.
Superradiant Quantum Heat Engine
Ali Ü. C. Hardal; Özgür E. Müstecapl?oglu
2015-04-22
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.
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)
2014-05-07
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.