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Directed selective tunneling of dipolar bosons in a driven triple well

Physical Review A 2014年第3期89卷 033428-033428页

作者： Gengbiao Lu Li-Bin Fu Jie Liu Wenhua Hai Institute of Applied Physics and Computational Mathematics Beijing 100088 People's Republic of China Department of Physics and Electronic Science Changsha University of Science and Technology Changsha 410004 China Department of Physics Hunan Normal University Changsha 410081 People's Republic of China

We study the coherent control of quantum tunneling for dipolar bosons held in a driven triple-well potential. In the high-frequency region within the resonance case, based on the non-Floquet solutions of two dipolar bosons, the influence of dipolar interaction on tunneling is investigated analytically and numerically, in which the directed selective-tunneling of a single atom is demonstrated when the two bosons are located in the middle well initially. Further, the corresponding effect is exhibited numerically for more dipolar atoms N>2 and the directed tunneling of 1 or (N−1) atoms occurs by adjusting the driving parameters. These results may be useful in the design of atomic devices.

关键词： BOSONS TUNNELING (physics) QUANTUM mechanics QUANTUM wells FLOQUET theory

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EXISTENCE UNIQUENESS AND DECAY OF SOLUTION FOR FRACTIONAL BOUSSINESQ APPROXIMATION

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Acta Mathematica Scientia 2013年第4期33卷 883-900页

作者：郭春晓张景军郭柏灵 Department of Mathematics China University of Mining and Technology (Beijing) College of Mathematics Physics and Information Engineering Jiaxing University Institute of Applied Physics and Computational Mathematics

The Boussinesq approximation finds more and more frequent use in geologi- cal practice. In this paper, the asymptotic behavior of solution for fractional Boussinesq approximation is studied. After obtaining some a priori estimates with the aid of eommu- tator estimate, we apply the Galerkin method to prove the existence of weak solution in the case of periodic domain. Meanwhile, the uniqueness is also obtained. Because the results obtained are independent of domain, the existence and uniqueness of the weak solution for Cauchy problem is also true. Finally, we use the Fourier splitting method to prove the decay of weak solution in three cases respectively.

关键词： fractional Boussinesq approximation commutator estimate Galerkinmethod decay of solutions

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Asymptotic Analysis of Quantum Dynamics in Crystals: the Bloch-Wigner Transform, Bloch Dynamics and Berry Phase

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Acta Mathematicae Applicatae Sinica 2013年第3期29卷 465-476页

作者： Weinan E Jian-feng LU Xu YANG Department of Mathematics Princeton University Program in Applied and Computational Mathematics Princeton University School of Mathematical Sciences Peking University

We study the semi-classical limit of the Schro¨dinger equation in a crystal in the presence of an external potential and magnetic field. We first introduce the Bloch-Wigner transform and derive the asymptotic equations governing this transform in the semi-classical setting. For the second part, we focus on the appearance of the Berry curvature terms in the asymptotic equations. These terms play a crucial role in many important physical phenomena such as the quantum Hall effect. We give a simple derivation of these terms in different settings using asymptotic analysis.

关键词： semiclassical limit Bloch-Wigner transform Bloch dynamics Berry phase asymptotic analysis

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Low dispersion finite volume scheme based on reconstruction with minimized dispersion and controllable dissipation

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Science China(physics,Mechanics & Astronomy) 2013年第2期56卷 423-431页

作者： WANG QiuJu REN YuXin SUN ZhenSheng SUN YuTao Department of Engineering Mechanics School of AerospaceTsinghua University Institute of Applied Physics and Computational Mathematics

The reconstruction with minimized dispersion and controllable dissipation(MDCD) optimizes dispersion and dissipation separately and shows desirable properties of both dispersion and dissipation.A low dispersion finite volume scheme based on MDCD reconstruction is proposed which is capable of handling flow discontinuities and resolving a broad range of length *** the proposed scheme is formally second order accurate,the optimized dispersion and dissipation make it very accurate and robust so that the rich flow features encountered in practical engineering applications can be handled properly.A number of test cases are computed to verify the performances of the proposed scheme.

关键词： low dispersion reconstruction finite volume scheme

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Collision of counterpropagating laser-excited wake bubbles

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Physical Review E 2014年第6期89卷 063101-063101页

作者： Z. G. Deng L. Yang C. T. Zhou M. Y. Yu H. P. Ying X. G. Wang Department of Physics Zhejiang University Hangzhou 310027 China School of Physics and Information Technology Shaanxi Normal University Xi'an 710062 China Institute for Fusion Theory and Simulation Zhejiang University Hangzhou 310027 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China

The collision of wake bubbles behind two counterpropagating laser pulses in rarefied plasma is investigated using particle-in-cell simulation. Special attention is paid to the highly nonlinear dynamics of the electrons in the interaction region. It is found that, as the two bubbles approach each other and collide, the electrons in the interaction region first oscillate in a periodic fashion, forming a quasistationary dense electron density ripple with fairly regular spatial structure. At longer times, the electron motion becomes chaotic, and the density grating is gradually smeared. The electrons escape in the transverse direction, and eventually the two bubbles merge to form a single one. The transition of the electron motion from regular to chaotic is confirmed by analytical modeling using test electrons moving in counterpropagating planar electromagnetic waves. The findings shed light on the dynamics of wake-bubble collisions and the complex behavior induced by multiple laser pulses in plasmas.

关键词： LASER pulses RAREFIED plasmas ELECTRONS -- Research ELECTRON density ELECTROMAGNETIC waves COLLISIONS (physics) MATHEMATICAL models

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Variation of implosion asymmetry with hohlraum length and timein indirect-drive Inertial Confinement Fusion

Variation of implosion asymmetry with hohlraum length and ti...

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The 2nd International Conference on High Energy Density physics,Beijing,China

作者： H.Li Y.D.Pu L.F.Jing Z.W.Lin B.L.Chen W.Jiang J.Y.Zhou T.X.Huang H.Y.Zhang R.Z.Yu J.Y.Zhang W.Y.Miao Z.J.Zheng Z.R.Cao J.M.Yang S.Y.Liu S.E.Jiang Y.K.Ding L.Y.Kuang G.Y.Hu J.Zheng C.S.Wu Y.Q.Zhao J.F.Gu D.G Kang K.Lan Research Center of Laser Fusion China Academy of Engineering Physics CAS Key Laboratory of Basic Plasma Physics and Department of Modern Physics University of Science and Technology of China Institute of Applied Physics and Computational Mathematics

In order to achieve the high density compression in laser indirect-drive inertial confinement fusion,the implosion symmetry and hohlraum radiation uniformity are strictly *** study the variations of implosion asymmetry with hohlraum length and time,three kinds of hohlraum lengths are adopted in experiment.X-ray emission from capsule fuel is measured by an X-ray framing *** on measured

关键词： Variation of implosion asymmetry with hohlraum length and timein indirect-drive Inertial Confinement Fusion

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Study of photocurrent generation in InP nanowire-based p＋-i-n＋ photodetectors

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Nano Research 2014年第4期7卷 544-552页

作者： Vishal Jain Ali Nowzari Jesper Wallentin Magnus T. Borgstrom Maria E. Messing Damir Asoli Mariusz Graczyk Bemd Witzigmann Federico Capasso Lars Samuelson Hakan Pettersson Solid State Physics and the Nanometer Structure Consortium Lund University Box 118 5E-221 O0 Lund Sweden Laboratory of Mathematics Physics and Electrical Engineering Halmstad University Box 823 SE-301 - 18 Halmstad Sweden Sol Voltaics AB Ideon Science Park Scheelevagen 17 SE-22370 Lund Sweden Department of Computational Electronics and Photonics University ofKassel Wilhelmshoeher Allee 71 D-34121 Kassel Germany School of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 USA

We report on electrical and optical properties of p＋-i-n＋ photodetectors/solar cells based on square millimeter arrays of InP nanowires （NWs） grown on InP substrates. The study includes a sample series where the p＋-segment length was varied between 0 and 250 nm, as well as solar cells with 9.3% efficiency with similar design. The electrical data for all devices display clear rectifying behavior with an ideality factor between 1.8 and 2.5 at 300 K. From spectrally resolved photocurrent measurements, we conclude that the photocurrent generation process depends strongly on the p^-segment length. Without a p＋-segment, photogenerated carriers funneled from the substrate into the NWs contribute strongly to the photocurrent. Adding a p＋-segment decouples the substrate and shifts the depletion region, and collection of photogenerated carriers, to the NWs, in agreement with theoretical modeling. In optimized solar cells, clear spectral signatures of interband transitions in the zinc blende and wurtzite InP layers of the mixed-phase i-segments are observed. Complementary electroluminescence, transmission electron microscopy （TEM）, as well as measurements of the dependence of the photocurrent on angle of incidence and polarization, support our interpretations.

关键词： nanophotonics nanowires infrared （IR） photodetectors solar cells

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Nonsequential double ionization of nonaligned diatomic molecules N_2 and O_2

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Chinese physics B 2013年第1期22卷 214-217页

作者：贾欣燕樊代和李卫东陈京 Quantum Optoelectronics Laboratory Southwest Jiaotong University Institute of Theoretical Physics and Department of Physics Shanxi University HEDPS Center for Applied Physics and Technology Peking University Institute of Applied Physics and Computational Mathematics

Nonsequential double ionization （NSDI） processes of nonaligned diatomic molecules N2 and O2 are studied using the S-matrix theory. Our results show that the NSDI process significantly depends on the molecular symmetry and structure. The ratio of NSDI rate to single ionization rate as a function of the field intensity is obtained. It is found that N2 behaves closely with its companion atom Ar in the ratios over the entire intensity range, while O2 exhibits an obvious suppression effect, which is qualitatively consistent with the experiment.

关键词： nonsequential double ionization nonaligned diatomic molecules S-matrix theory suppression

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Marginal stability in jammed packings: Quasicontacts and weak contacts

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Physical Review E 2014年第2期90卷 022114-022114页

作者： Yoav Kallus Salvatore Torquato Department of Physics Princeton University Princeton New Jersey 08544 USA Department of Chemistry Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA and Princeton Institute of the Science and Technology of Materials Princeton University Princeton New Jersey 08544 USA

Maximally random jammed (MRJ) sphere packing is a prototypical example of a system naturally poised at the margin between underconstraint and overconstraint. This marginal stability has traditionally been understood in terms of isostaticity, the equality of the number of mechanical contacts and the number of degrees of freedom. Quasicontacts, pairs of spheres on the verge of coming in contact, are irrelevant for static stability, but they come into play when considering dynamic stability, as does the distribution of contact forces. We show that the effects of marginal dynamic stability, as manifested in the distributions of quasicontacts and weak contacts, are consequential and nontrivial. We study these ideas first in the context of MRJ packing of d-dimensional spheres, where we show that the abundance of quasicontacts grows at a faster rate than that of contacts. We reexamine a calculation of Jin et al. [Phys. Rev. E 82, 051126 (2010)], where quasicontacts were originally neglected, and we explore the effect of their inclusion in the calculation. This analysis yields an estimate of the asymptotic behavior of the packing density in high dimensions. We argue that this estimate should be reinterpreted as a lower bound. The latter part of the paper is devoted to Bravais lattice packings that possess the minimum number of contacts to maintain mechanical stability. We show that quasicontacts play an even more important role in these packings. We also show that jammed lattices are a useful setting for studying the Edwards ensemble, which weights each mechanically stable configuration equally and does not account for dynamics. This ansatz fails to predict the power-law distribution of near-zero contact forces, P(f)∼fθ.

关键词： SPHERE packings POWER law (mathematics) computational complexity NP-hard problems BRAVAIS lattice

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Precision Relativistic eigenchannel R-matrix calculation Of Ne+ discrete energy region scattering matrix

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Journal of physics: Conference Series 2015年第9期635卷

作者： Rui Jin Xiao-Ying Han Xiang Gao De-Ling Zeng Jia-Ming Li Department of Physics and Center for Atomic and Molecular Nanosciences Tsinghua University Beijing 100084 China Beijing Computational Science Research Center Beijing 100084 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics and Astronomy Shanghai Jiaotong University Shanghai 200240 China Collaborative Innovation Center of Quantum Matter Beijing 100084 China

With our relativistic eigenchannel R-matrix method R-R-Eigen, the physics parameters of Ne+ in multi channel quantum defect theory (MQDT) are calculated directly, such as eigenchannel quantum defects, transformation matrix etc al. Various physical quantities can then be derived from a straightforward application of the MQDT procedure. Using our proposed projected high dimensional quantum-defect graph (symmetrized) - a generalization of Lu-Fano plots, we can readily determine the accuracies of the calculated MQDT physical parameters (ie. scattering matrix) systematically against the experimental energy levels. Based on the analytical continuation property of short-range scattering matrix below and above threshold, the origin of each resonant peak observed in the experiment can be designated. there is possibility to adjust calculated total photoionization spectra to fit the experiment.

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