BCS-BEC渡越过程中超流费米气体Efimovian膨胀的研究  

Efimovian expansion of a superfluid Fermi gas in the BCS-BEC crossover

作　　者：张亮 文文 马晓栋[3] ZHANG Liang;WEN Wen;MA Xiao-Dong(College of Science,Hohai University,Nanjing 210098,China;Department of Mathematics and Physics,Hohai University, Changzhou 213022,China;College of Physics and Electronic Engineering,Xinjiang Normal University,Urumchi 830054,China)

机构地区：[1]河海大学理学院,南京210098 [2]河海大学常州校区基础学部,常州213022 [3]新疆师范大学物理与电子工程学院,乌鲁木齐830054

出　　处：《原子与分子物理学报》2018年第5期803-809,共7页Journal of Atomic and Molecular Physics

基　　金：国家自然科学基金(11105039);中央高校基本科研业务费专项资金(2017B18014)

摘　　要：基于耦合流体力学方程组,分别研究了各向同性和各向异性轴对称势阱下Bardeen-CooperSchrieffer–Bose-Einstein condensate(BCS-BEC)渡越过程中超流费米气体的Efimovian膨胀.当费米气体处于幺正极限,体系标度不变,气体膨胀尺寸展现出一系列平台结构,气体的演化由对数周期函数描述;当费米气体处于非幺正极限超流区域,体系标度不变性破缺,气体的演化偏离对数周期变化;另外我们还发现对于各向异性的费米气体,即使处于幺正极限,谐振子势的各向异性也会导致体系标度不变性破缺.Based on the coupled superfluid hydrodynamic equations,we study the Efimovian expansions of the superfluid Fermi gases in the BCS-BEC crossover released from an isotropic trap and a axially symmetric anisotropic trap,respectively.For the superfluid Fermi gas in the unitary limit which is scale invariant,the Efimovian expansion of cloud size exhibits a sequence of plateaus and the expansion dynamics is characterized by log-periodic oscillations.For the superfluid Fermi gases in the non-unitary regime where the scale invariance is broken,the expansion deviates the character of the sequence of plateaus and the expansion dynamics exhibits non-log-periodic oscillations.We also find that even for a unitary Fermi gas,the anisotropy of the harmonic trap can break the scale invariance of the system.

关 键 词：超流费米原子气体 BCS-BEC渡越 Efimovian膨胀 标度不变性破缺 

分 类 号：O561[理学—原子与分子物理]