双分量玻色气体在有限温度下的力学稳定性和相分离  

Mechanical Stability and Phase Separation of Two-Component Bose Gas at Finite Temperature

作　　者：高佩佩 贺丽[2] 余增强[1] GAO Peipei;HE Li;YU Zengqiang(Institute of Theoretical Physics,Shanxi University,Taiyuan 030006,China;College of Physics and Electronic Engineering,Taiyuan 030006,China)

机构地区：[1]山西大学理论物理研究所,山西太原030006 [2]山西大学物理电子工程学院,山西太原030006

出　　处：《山西大学学报（自然科学版）》2019年第3期568-575,共8页Journal of Shanxi University(Natural Science Edition)

基　　金：国家自然科学基金(11674202);山西省应用基础研究项目(201601D011014)

摘　　要：运用Hartree-Fock平均场理论研究了赝自旋为1/2的双分量玻色气体在有限温度的相图。当相同自旋原子间具有排斥互作用、相反自旋原子间具有吸引相互作用时,均匀体系会在中等密度的一定范围内出现力学不稳定性,从而导致正常相与玻色-爱因斯坦凝聚相之间的相分离。类似于经典气液相变,物态方程给出的等温曲线在两相共存区呈现特征性的饱和气压平台。在简谐势阱中,相分离造成原子密度在相边界处出现跳变,跳变幅度依赖于温度与相互作用强度。The phase diagram of a pseudospin-half Bose gas at finite temperature is studied according to Hartree-Fock mean-field theory.When the intra-spin interaction is repulsive and inter-spin interaction is attractive,a homogeneous system suffers the mechanical instability within a range of medium density,consequently,a separation between the normal phase and Bose-Einstein condensation phase takes places.Similar to a classical gas-liquid transition,the isothermal equation-of-state shows a characteristic horizonal portion at saturated pressure when the two separated phases coexist.In presence of a harmonic trap,the phase separation can be observed through the density profile of the atomic cloud,which exhibits a sudden jump at the phase boundary.The amplitude of the density jump depends on both temperature and interaction strength.

关 键 词：玻色气体 热力学相变 物态方程 玻色-爱因斯坦凝聚 

分 类 号：O51[理学—低温物理]