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The ground states and pseudospin textures of rotating two-component Bose–Einstein condensates trapped in harmonic plus quartic potential

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Chinese physics B 2016年第9期25卷 219-226页

作者：刘燕张素英 institute of theoretical physics Shanxi University

The ground states of two-component miscible Bose–Einstein condensates（BECs） confined in a rotating annular trap are obtained by using the Thomas–Fermi（TF） approximation *** ground state density distribution of the condensates experiences a transition from a disc shape to an annulus shape either when the angular frequency increases and the width and the center height of the trap are fixed,or when the width and the center height of the trap increase and the angular frequency is *** the numerical solutions of the ground states of the trapped two-component miscible BECs with the same condition are obtained by using imaginary-time propagation *** are in good agreement with the solutions obtained by the TF approximation *** ground states of the trapped two-component immiscible BECs are also given by using the imaginary-time propagation ***,by introducing a normalized complex-valued spinor,three kinds of pseudospin textures of the BECs,i.e.,giant skyrmion,coaxial double-annulus skyrmion,and coaxial three-annulus skyrmion,are found.

关键词： Bose–Einstein condensate pseudospin texture skyrmion

Comparison of dark energy models:A perspective from the latest observational data

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Science China(physics,Mechanics & Astronomy) 2010年第9期53卷 1631-1645页

作者： LI Miao1,2,LI XiaoDong2,3 & ZHANG Xin1,4 1Kavli institute for theoretical physics China,Chinese Academy of Sciences,Beijing 100190,China 2Key Laboratory of Frontiers in theoretical physics,institute of theoretical physics,Chinese Academy of Sciences,Beijing 100190,China 3interdisciplinary Center for theoretical Study,University of Science and Technology of China,Hefei 230026,China 4Department of physics,College of Sciences,Northeastern University,Shenyang 110004,China Kavli institute for theoretical physics China Chinese Academy of Sciences Beijing China Key Laboratory of Frontiers in theoretical physics Institute of Theoretical Physics Chinese Academy of Sciences Beijing China interdisciplinary Center for theoretical Study University of Science and Technology of China Hefei China Department of physics College of Sciences Northeastern University Shenyang China

We compare some popular dark energy models under the assumption of a flat universe by using the latest observational data including the type Ia supernovae Constitution compilation,the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey,the cosmic microwave background measurement given by the seven-year Wilkinson Microwave Anisotropy Probe observations and the determination of H0 from the Hubble Space *** comparison statistics such as the Bayesian and Akaike information criteria are applied to assess the worth of the *** statistics favor models that give a good fit with fewer *** on this analysis,we find that the simplest cosmological constant model that has only one free parameter is still preferred by the current *** other dynamical dark energy models,we find that some of them,such as the αdark energy,constant w,generalized Chaplygin gas,Chevalliear-Polarski-Linder parametrization,and holographic dark energy models,can provide good fits to the current data,and three of them,namely,the Ricci dark energy,agegraphic dark energy,and Dvali-Gabadadze-Porrati models,are clearly disfavored by the data.

关键词： dark energy models observational constraints model comparison information criteria

Quantum Gravitational Contributions to Gauge Field Theories

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Communications in theoretical physics 2012年第4期57卷 629-636页

作者：汤勇吴岳良 Kavli institute for theoretical physics China(KITPC) State Key Laboratory of Theoretical Physics(SKLTP)Institute of Theoretical PhysicsChinese Academy of Science

We revisit quantum gravitational contributions to quantum gauge field theories in the gauge condition independent Vilkovisky-DeWitt formalism based on the background field *** the advantage of Landau-DeWitt gauge,we explicitly obtain the gauge condition independent result for the quadratically divergent gravitational corrections to gauge *** employing,in a general way,a scheme-independent regularization method that can preserve both gauge invariance and original divergent behavior of integrals,we show that the resulting gauge coupling is power-law running and asymptotically *** regularization scheme dependence is clarified by comparing with results obtained by other *** loop regularization scheme is found to be applicable for a consistent calculation.

关键词： quantum gravity Vilkovisky-DeWitt asymptotic freedom

The( p, q) inflation model

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Science China(physics,Mechanics & Astronomy) 2015年第11期58卷 63-67页

作者： HUANG QingGuo State Key Laboratory of theoretical physics Institute of Theoretical Physics Chinese Academy of Sciences

In this paper we propose a new inflation model named( p, q) inflation model in which the inflaton potential contains both positive and negative powers of inflaton field in the polynomial form. We derive the accurate predictions of the canonical single-field slow-roll inflation model. Using these formula, we show that our inflation model can easily generate a large amplitude of tensor perturbation and a negative running of spectral index with large absolute value.

关键词： inflation tensor-to-scalar ratio spectral index running of spectral index

Orientation dependence of structural transition in fcc Al driven under uniaxial compression by atomistic simulations

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Chinese physics B 2011年第4期20卷 391-396页

作者：李莉邵建立段素青梁九卿 institute of theoretical physics and Department of physics Shanxi University institute of Applied physics and Computational Mathematics

By molecular dynamics simulations employing an embedded atom method potential, we have investigated structural transformations in single crystal A1 caused by uniaxial strain loading along the [001], [011] and [111] directions. We find that the structural transition is strongly dependent on the crystal orientations. The entire structure phase transition only occurs when loading along the [001] direction, and the increased amplitude of temperature for [001] loading is evidently lower than that for other orientations. The morphology evolutions of the structural transition for [011] and [111] loadings are analysed in detail. The results indicate that only 20% of atoms transit to the hcp phase for [011] and [111] loadings, and the appearance of the hcp phase is due to the partial dislocation moving forward on {lll}fcc family. For [011] loading, the hcp phase grows to form laminar morphology in four planes, which belong to the {111}fcc family; while for [111] loading, the hcp phase grows into a laminar structure in three planes, which belong to the {111}fcc family except for the （111） plane. In addition, the phase transition is evaluated by using the radial distribution functions.

关键词： single crystal Al molecular dynamics simulations uniaxial compression phase transition

Critical entanglement and geometric phase of a two-qubit model with Dzyaloshinski-Moriya anisotropic interaction

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Chinese physics B 2010年第1期19卷 51-55页

作者：李志坚程璐温姣进 institute of theoretical physics and Department of physics Shanxi University

We consider a two-qubit system described by the Heisenberg XY model with Dzyaloshinski Moriya （DM） anisotropic interaction in a perpendicular magnetic field to investigate the relation between entanglement, geometric phase and quantum phase transition （QPT）. It is shown that the DM interaction has an effect on the critical boundary. The combination of entanglement and geometric phase may characterize QPT completely. Their jumps mean that the occurrence of QPT and inversely the QPT at the critical point at least corresponds to a jump of one of them.

关键词： entanglement geometric phase quantum phase transition

The elastic properties and energy characteristics of Au nanowires:an atomistic simulation study

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Chinese physics B 2008年第7期17卷 2621-2626页

作者：刘珊珊文玉华朱梓忠 Department of physics and Institute of Theoretical Physics and AstrophysicsXiamen University

This paper have performed molecular static calculations with the quantum corrected Sutten Chen type many body potential to study size effects on the elastic modulus of Au nanowires with [100], [110] and [111] crystallographic directions, and to explore the preferential growth orientation of Au nanowires. The main focus of this work is the size effects on their surface characteristics. Using the common neighbour analysis, this paper deduces that surface region approximately consists of two layer atoms. Further, it extracts the elastic modulus of surface, and calculate surface energy of nanowire. The results show that for all three directions the Young＇s modulus of nanowire increases as the diameter increases. Similar trend has been observed for the Young＇s modulus of surface. However, the atomic average potential energy of nanowire shows an opposite change. Both the potential and surface energy of [110] nanowire are the lowest among all three orlentational nanowires, which helps to explain why Au nanowires possess a [110] preferred orientation during the experimental growth proceeds.

关键词： nanowire elastic modulus size effect molecular static approach

Theory of specific heat of vortex liquid of high T_c superconductors

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Chinese physics B 2016年第10期25卷 398-402页

作者：白晨迟诚王江帆 institute of theoretical physics School of Physics Peking University

Superconducting thermal fluctuation(STF) plays an important role in both thermodynamic and transport properties in the vortex liquid phase of high *** was widely observed in the vicinity of the critical transition *** the framework of Ginz burg-Landau-La wrence-Doniach theory in magnetic field,a self-consistent analysis of STF including all Landau levels is *** that,we calculate the contribution of STF to specific heat in vortex liquid phase for high Tcuprate superconductors,and the fitting results are in good agreement with experimental data.

关键词： superconducting thermal fluctuation vortex liquid self-consistent approximation specific heat

Superballistic wavepacket spreading in double kicked rotor

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Science China(physics,Mechanics & Astronomy) 2016年第8期59卷 9-15页

作者： Ping Fang Jiao Wang Department of physics and institute of theoretical physics and Astrophysics Xiamen University

We investigate possible ways in which a quantum wavepacket spreads. We show that in a general class of double kicked rotor system, a wavepacket may undergo superballistic spreading; i.e., its variance increases as the cubic of time. The conditions for the observed superballistic spreading and two related characteristic time scales are studied. Our results suggest that the symmetry of the studied model and whether it is a Kolmogorov-Arnold-Moser system are crucial to its wavepacket spreading behavior. Our study also sheds new light on the exponential wavepacket spreading phenomenon previously observed in the double kicked rotor system.

关键词： quantum chaos quantum transport matter waves semiclassical methods