理想玻色气体的焦汤系数

应用玻色系统的基本方程，玻色积分的特性以及热力学理论，导得理想玻色气体焦汤系数的解析表达式，详细讨论了低温下玻色气体的定压热容和焦汤系数，阐明了系统的量子本性对焦汤系数的贡献，表明理想玻色气体适用于低温制冷系统。     

A path integral centroid molecular dynamics method for Bose and Fermi statistics

We propose a path integral centroid molecular dynamics (CMD) method extended to Bose and Fermi statistics. An extended method of path integral molecular dynamics (PIMD) for such statistics is also developed as a technique of calculations of static properties. Bose PIMD and CMD simulations have been performed for bulk liquid ⁴He and ideal Bose gas, respectively. The remnant of λ transition is observed for bulk liquid ⁴He, while the effect of Bose statistics on the centroid dynamics spanning several nanoseconds is observed for ideal Bose gas.     

Virial Coefficients from Unified Statistical Thermodynamics of Quantum Gases Trapped under Generic Power Law Potential in d Dimension and Equivalence of Quantum Gases

From the unified statistical thermodynamics of quantum gases, the virial coefficients of ideal Bose and Fermi gases, trapped under generic power law potential are derived systematically. From the general result of virial coefficients, one can produce the known results in d=3 and d=2. But more importantly we found that, the virial coefficients of Bose and Fermi gases become identical (except the second virial coefficient, where the sign is different) when the gases are trapped under harmonic potential in d=1. This result suggests the equivalence between Bose and Fermi gases established in d=1 (J. Stat. Phys. DOI 10.1007/s10955-015-1344-4). Also, it is found that the virial coefficients of two-dimensional free Bose (Fermi) gas are equal to the virial coefficients of one-dimensional harmonically trapped Bose (Fermi) gas.     

Helium-4 Bose fluids formed in one-dimensional 18 A diameter pores

Bose fluids restricted in one dimension (1D) are realized by adsorbing 4He atoms on the 1D pore walls with a diameter of about 18 A. The Bose fluid appears above an adsorbed amount after the pore walls are coated with the inert 4He atoms. Heat capacity of the fluid was observed to have a temperature-linear term at low temperatures. This corresponds to the phonon heat capacity of the Bose fluid in the 1D pores. We estimate the phonon velocity and the interaction of the 1D Bose fluid.     

Quasi-one-dimensional Bose gases with a large scattering length

Bose gases confined in highly elongated harmonic traps are investigated over a wide range of interaction strengths using quantum Monte Carlo techniques. We find that the properties of a Bose gas under tight transverse confinement are well reproduced by a 1D model Hamiltonian with contact interactions. We point out the existence of a unitary regime, where the properties of the quasi-1D Bose gas become independent of the actual value of the 3D scattering length a(3D). In this unitary regime, the energy of the system is well described by a hard-rod equation of state. We investigate the stability of quasi-1D Bose gases with positive and negative a(3D).     

Critical behaviour of a relativistic ideal Bose gas with pair production

We discuss the critical behaviour of an ideal relativistic Bose gas (in d dimensions) with a net charge including the effects of pair production. We show that the critical exponents of the system are the same as those of the usual nonrelativistic Bose gas. The universal ratios formed from the critical amplitude are also the same as those of the usual Bose gas.     

玻色-爱因斯坦凝聚的相变特征

研究玻色-爱因斯坦凝聚的相变特征，证明了粒子间存在弱排斥相互作用的玻色系统的玻色-爱因斯坦凝聚是二级相变。     

Isobaric Heat Capacity of an Ideal Bose Gas

It is demonstrated that the heat capacity of an ideal Bose gas at constant pressure increases infinitely when its temperature approaches the Bose condensation temperature from above and is infinite for the phase with a Bose condensate.     

Photon condensation: A new paradigm for Bose–Einstein condensation

Bose–Einstein condensation is a state of matter known to be responsible for peculiar properties exhibited by superfluid Helium-4 and superconductors. Bose–Einstein condensate (BEC) in its pure form is realizable with alkali atoms under ultra-cold temperatures. In this paper, we review the experimental scheme that demonstrates the atomic Bose–Einstein condensate. We also elaborate on the theoretical framework for atomic Bose–Einstein condensation, which includes statistical mechanics and the Gross–Pitaevskii equation. As an extension, we discuss Bose–Einstein condensation of photons realized in a fluorescent dye filled optical microcavity. We analyze this phenomenon based on the generalized Planck’s law in statistical mechanics. Further, a comparison is made between photon condensate and laser. We describe how photon condensate may be a possible alternative for lasers since it does not require an energy consuming population inversion process.     

On the theory of slowing down gracefully

We discuss the transport of a tracer particle through the Bose?CEinstein condensate of a Bose gas. The particle interacts with the atoms in the Bose gas through two-body interactions. In the limiting regime where the particle is very heavy and the Bose gas is very dense, but very weakly interacting (??mean-field limit??), the dynamics of this system corresponds to classical Hamiltonian dynamics. We show that, in this limit, the particle is decelerated by emission of gapless modes into the condensate (Cerenkov radiation). For an ideal gas, the particle eventually comes to rest. In an interacting Bose gas, the particle is decelerated until its speed equals the propagation speed of the Goldstone modes of the condensate. This is a model of ??Hamiltonian friction??. It is also of interest in connection with the phenomenon of ??decoherence?? in quantum mechanics. This note is based on work we have carried out in collaboration with D Egli, I M Sigal and A Soffer.     

General structure of bose-einstein condensates with arbitrary spin

Motivated by the recent discoveries of spin-1 and pseudo-spin-1/2 Bose gas, we have studied the general structure of the Bose gases with arbitrary spin. A general method is developed to uncover the elementary building blocks of the angular momentum eigenstates, as well as the relations (or interactions) between them. Applications of this method to Bose gas with integer spins ( f = 1,2,3) and half integer spins ( f = 1/2,3/2) reveal many surprising structures.     

Old mathematical errors in statistical physics

In this paper, we discuss the following questions of quantum statistics: (1) the absence of Bose condensate in ideal Bose gas in the two-dimensional and one-dimensional case; (2) the concentration of the Bose condensate in an ideal Bose gas at the lowest level of the spectrum of the Schrödinger operator. In classical statistics, we discuss the discrepancy between the notion of Boltzman-Maxwell ideal gas with the notion of saturated vapor. The appearance of clusters requires the complete revision of the Clayperon equation as an equation depending on the number of degrees of freedom. For the new ideal gas and the ideal virtual liquid, we describe the phase transition of the first kind by specifying the concept of negative pressure for ideal virtual liquids.     

Soliton trains in Bose-Fermi mixtures

We theoretically consider the formation of bright solitons in a mixture of Bose and Fermi degenerate gases. While we assume the forces between atoms in a pure Bose component to be effectively repulsive, their character can be changed from repulsive to attractive in the presence of fermions provided the Bose and Fermi gases attract each other strongly enough. In such a regime the Bose component becomes a gas of effectively attractive atoms. Hence, generating bright solitons in the bosonic gas is possible. Indeed, after a sudden increase of the strength of attraction between bosons and fermions (realized by using a Feshbach resonance technique or by firm radial squeezing of both samples) soliton trains appear in the Bose-Fermi mixture.     

Cold Bose stars

By solving the Einstein equations coupled to a noninteracting quantum Bose field we determine the mass, density, and radius of equilibrium states of cold Bose matter localized under its own gravity. In particular we find that the maximum mass of a cold Bose star is 0.633/Gm.     

Analytical approach to quantum phase transitions of ultracold Bose gases in bipartite optical lattices using the generalized Green’s function method

In order to investigate the quantum phase transitions and the time-of-flight absorption pictures analytically in a systematic way for ultracold Bose gases in bipartite optical lattices, we present a generalized Green’s function method. Utilizing this method, we study the quantum phase transitions of ultracold Bose gases in two types of bipartite optical lattices, i.e., a hexagonal lattice with normal Bose–Hubbard interaction and a d-dimensional hypercubic optical lattice with extended Bose–Hubbard interaction. Furthermore, the time-of-flight absorption pictures of ultracold Bose gases in these two types of lattices are also calculated analytically. In hexagonal lattice, the time-of-flight interference patterns of ultracold Bose gases obtained by our analytical method are in good qualitative agreement with the experimental results of Soltan-Panahi, et al. [Nat. Phys. 7, 434 (2011)]. In square optical lattice, the emergence of peaks at \(\left( { \pm \frac{\pi }{a}, \pm \frac{\pi }{a}} \right)\) in the time-of-flight absorption pictures, which is believed to be a sort of evidence of the existence of a supersolid phase, is clearly seen when the system enters the compressible phase from charge-density-wave phase.     

On the theory of superfluidity

We investigate the properties of dispersion spectra of one-dimensional periodic Bose systems with repulsive interparticle interactions. These systems with sufficient large interactions can support metastable supercurrent states, which correspond to the local minima of the dispersion spectra at non-zero momenta. The existence of local minima in the spectra and the energy barriers, which separate the minima, can be explained in terms of Bose exchange symmetry. We extend our study to the case of higher dimensional Bose systems. We suggest that superfluidity could be understood as a Bose exchange effect.     

相互作用对玻色气体热力学性质及稳定性的影响

根据由赝势法得到的非理想玻色气体的自由能和状态方程，研究了相互作用对凝聚温度的影响.从热力学角度揭示了存在引力作用时定压热容量、等温压缩系数、定压膨胀系数的反常热力学特性.研究了引力作用下玻色气体系统的不稳定性，给出了不稳定性的温度判据和粒子数密度判据. 关键词： 相互作用 玻色气体 热力学性质 不稳定性判据     

On Condensations in the Bogoliubov Weakly Imperfect Bose Gas

We show that condensation in the Bogoliubov weakly imperfect Bose gas (WIBG) may appear in two stages. If interaction is such that the pressure of the WIBG does not coincide with the pressure of the perfect Bose gas (PBG), then the WIBG may manifest two kinds of condensations: nonconventional Bose condensation in zero mode, due to the interaction (the first stage), and conventional (generalized) Bose–Einstein condensation in modes next to the zero mode due to the particle density saturation (the second stage). Otherwise the WIBG manifests only the latter kind of condensation.     

多粒子玻色关联对夸克胶子等离子体颗粒源的检测

对由空间离散分布的夸克－胶子等离子体热滴发射的玻色子，本文进行了多粒子玻色关联的蒙特卡罗模拟研究．与两粒子玻色关联相比，多粒子玻色关联能够更敏感地检测玻色子发射源的颗粒性．通过对多粒子可观测量的分析，能够获得夸克－胶子等离子体和强子气体混合相存在的检测信号．     

Multiparticle Bose Correlations: Probes for Granular Source of Quark-Glunon-Plasma Droplets

The multiparticle Bose correlations of bosons emitted from dispersed thermal droplets of quark-gluon plasma are simulated by Monte Carlo.Multiparticle Bose correlations can offer more sensitivity to probe the granularity of the Bosonemitting source than two-particle Bose correlations.A promising signal of the existence of a mixed phase of quark-gluon plasma and hadronic gas can be obtained from multiparticle observables.