应用保真度研究两腿XXZ梯子系统的量子相变  

Quantum Phase Transitions in a Two-leg XXZ Ladder:Ground-state Fidelity

作　　者：李生好[1] 雷国平[2] LI Shenghao;LEI Guoping(Chongqing Vocational Institute of Engineering, Chongqing 402260, China;College of Electronic and Information Engineering, Chongqing Three Gorges University, Chongqing 404000, China)

机构地区：[1]重庆工程职业技术学院,重庆402260 [2]重庆三峡学院电子与信息工程学院,重庆404000

出　　处：《量子光学学报》2018年第2期214-222,共9页Journal of Quantum Optics

基　　金：国家自然科学基金(11104362);重庆市基础科学与前沿技术研究专项项目(cstc2016jcyjA0480);重庆市教委科学技术研究项目(KJ1732433);重庆江津区科委研究项目(zzjh2015016)

摘　　要：本文基于投影纠缠对态的自旋梯子系统的张量网络算法提供了一个有效的方法,来研究两腿自旋1/2的XXZ梯子量子系统的量子临界性,通过与单位格点基态保真度相结合,得到清晰的基态保真度三维图,来探测量子多体系统的量子相变,从而可以绘制出两腿自旋1/2XXZ梯子量子模型的基态相图,在相图中出现铁磁（FM）相、条纹铁磁（SF）相、Néel（N）相、条纹Néel（SN）相、Rung singlet（RS）相、Haldane（H）相、Rung triplet（RT）相、临界XY相（XY1相和XY2相）。在不知道系统是否存在局域序参量或非局域序参量的情况下,可以通过系统的基态波函数,在对称性破缺相中由约化密度矩阵得到局域序参量;或者在对称性相中,找出系统存在的非局域序参量,来完整地描述系统的量子相变和量子临界现象。A two-leg XXZ spin S= 1/2 ladder system is systematically studied in terms of a algorithm, which is based on the tensor network representation of quantum many-hod adaptation of the projected entangled pair states to the geometry of translationally invari quantum spin ladders. Algorithm provides an effective method to generate the ground state tensor network y states as an ant infinite-size wave function, which, on the other hand, allows us to compute the ground-state fidelity per lattice site, a universal marker to detect phase transitions in a quantum many-body system. The ground-state phase diagram of the ladder system is mapped out, which exhibits a diverse of phases, including ferromagnetic, stripe ferromagnetic, rung singlet, rung triplet, Néel, stripe Néel, Haldane, XY1 and XY2 phases.

关 键 词：量子相变 相图 自旋梯子 保真度 张量网络 

分 类 号：O413[理学—理论物理]