双组分玻色-爱因斯坦凝聚体的混溶性  

Miscibility of dual-species Bose-Einstein condensates

作　　者：贺丽[1] 张天琪 李可芯 余增强[2,3] He Li;Zhang Tian-Qi;Li Ke-Xin;Yu Zeng-Qiang(College of Physics and Electronic Engineering,Shanxi University,Taiyuan 030006,China;Institute of Theoretical Physics,Shanxi University,Taiyuan 030006,China;State Key Laboratory of Quantum Optics and Quantum Optics Devices,Shanxi University,Taiyuan 030006,China)

机构地区：[1]山西大学物理电子工程学院,太原030006 [2]山西大学理论物理研究所,太原030006 [3]山西大学量子光学和光量子器件国家重点实验室,太原030006

出　　处：《物理学报》2023年第11期132-140,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12104275,12174230)资助的课题.

摘　　要：基于包含Lee-Huang-Yang修正的物态方程,研究了具有排斥相互作用的双组分玻色-爱因斯坦凝聚体在平均场弱失稳区间的基态相图.根据相平衡条件,确定了等质量混合体系中不混溶态、部分混溶态以及均匀混溶态之间的相边界.在原子密度足够稀薄的情形下,给出了相边界和量子临界点的解析表达式.讨论了密度响应的静态极化率在量子临界点附近的发散行为.对于不等质量的双组分凝聚体,利用低浓度展开的物态方程,得到了部分混溶态出现的阈值密度,并提出了判断部分混溶构型的解析方法,为钠、钾、铷等冷原子混合体系的实验观测提供了明确的理论指引.The miscibility of quantum liquids is an interesting topic in many-body physics,which has been intensively investigated in 3He-4He superfluids and the mixtures of ultracold atoms.In the context of dual species Bose-Einstein condensates,the mean-field description has been well established,according to which,the miscibility condition is density independent and determined only by the ratio of inter-and intra-species interaction strength.Recently,Nadion and Petrov proposed that[Phys.Rev.Lett.126115301],in the vicinity of the mixing-demixing threshold,quantum fluctuations play an important role to affect the equilibrium stability,and as a result,the partially miscible state emerges.This new phase of quantum matter opens up new perspectives to explore the beyond mean-field effect in ultracold atomic gases.In this work,according to the equation of state taking the Lee-Huang-Yang correction into consideration,we investigate the ground state phase diagram of repulsive binary Bose mixtures in the interacting regime suffering a weak mean-field instability.Under the thermodynamic balance conditions,the phase boundaries between the immiscible state,partially miscible state and the homogenous state are determined.For the equalmass case,these phase transitions only take place on condition that intra-species interactions are in an asymmetric form.In terms of interaction parameters,we explicitly derive analytical expressions of the phase boundaries,which are appropriate to describe the transitions in sufficiently dilute atomic gases.At the quantum critical point,where the partially miscible state terminates,the susceptibility tensor of the density response exhibits a divergent behavior.For the unequal-mass case,the beyond-mean-field equation of state cannot be written in a compact form,thus the determination of the phase boundaries is more involved.By expanding the Lee-Huang-Yang energy expression to the terms linear in the concentration of the minority species,we analytically obtain the threshold density for the partially miscib

关 键 词：玻色-爱因斯坦凝聚体 玻色混合物 混溶性 量子涨落 

分 类 号：O469[理学—凝聚态物理]