一维SOC晶格中In-plane Zeeman场驱动的量子相变  

Quantum Phase Transition drived by In-plane Zeeman Field in a One-dimensional SOC Lattice

作　　者：焦群[1] 梁军军[1] 

机构地区：[1]山西大学理论物理研究所,山西太原030006

出　　处：《山西大学学报（自然科学版）》2016年第3期452-456,共5页Journal of Shanxi University(Natural Science Edition)

基　　金：国家自然科学基金(11005071)

摘　　要：In-plane Zeeman场可以导致费米面变形使其产生不对称性,进而诱发很多新奇的物理现象,而自旋轨道耦合(SOC)则是近年来冷原子研究领域的热点。文章利用密度矩阵重整化群(DMRG)方法研究了in-plane Zeeman场和SOC作用下,一维光晶格中的吸引相互作用的费米气体的量子相变。研究发现:(i)in-plane Zeeman场能够引起非零动量Q配对,即FFLO态;(ii)SOC能使系统由FFLO态变为FFLO-BCS态,最终相变为BCS态;(iii)外势能引起FFLO-BCS态到BCS态的相变。The in-plane Zeeman field generates Fermi surface distortion,make it asymmetric and induces various novel physical phenomena; while Spin-Orbit Coupling （SOC）is a hotspot in the cold atoms research field in recent years. By employing the density matrix renomalization group（DMRG） method, we study the quantum phase transition of attractive Fermi gases confined in one-dimensional optical lattice and under the action of in-plane Zeeman field and SOC. The results demonstrated that： （i）in-plane Zeeman field causes the system appearing as a nonzero-momentum pairing, named FFLO state; （ii） in the presence of SOC, the system transforms from FFLO state into FFLO-BCS state and becomes BCS state eventually; （iii） it is the external potential makes the phase transition from FFLO-BCS state to BCS state.

关 键 词：IN-PLANE Zeeman场 密度矩阵重整化群 自旋轨道耦合 Fermi-Hubbard模型 

分 类 号：O469[理学—凝聚态物理]