周期驱动拉曼晶格系统中的动力学拓扑现象  

Dynamic topological phenomena in periodically driven Raman lattice

作　　者：蔡德欢 屈苏平[3] Cai De-Huan;Qu Su-Ping(Hefei National Laboratory,University of Science and Technology of China,Hefei 230088,China;CAS Center For Excellence in Quantum Information and Quantum Physics,Hefei 230026,China;Bengbu University,Bengbu 233030,China)

机构地区：[1]合肥国家实验室,合肥230088 [2]中国科学院量子信息与量子科技创新研究院,合肥230026 [3]蚌埠学院,蚌埠233030

出　　处：《物理学报》2024年第14期24-33,共10页Acta Physica Sinica

基　　金：科技创新2030-“量子通信与量子计算机”重大项目(批准号:2021ZD0301200);国家自然科学基金(批准号:11974331);安徽高校自然科学研究项目(批准号:KJ2021A1130);安徽省高校优秀青年人才支持计划(批准号:gxyq2022111)资助的课题.

摘　　要：基于目前超冷原子系统中模拟能带拓扑和动力学量子相变的有关实验进展,设计出一个时间周期驱动的一维拉曼晶格系统来模拟动力学拓扑现象.利用振幅周期调制的拉曼光束耦合类碱土^(171)Yb原子的{^(1)S_(0),^(3)P_(1)}能级可以实现所需要的周期驱动拉曼晶格系统.时间周期系统的单带紧束缚近似哈密顿量通过特定变换可以解析求得有效Floquet哈密顿量和微动算符(micromotion operator),从而可以在一维晶格系统中研究任意驱动频率下Floquet动力学量子相变和动力学斯格明子结构出现的条件.结果表明,拓扑非平庸的有效Floquet哈密顿量是系统出现Floquet动力学量子相变的充分不必要条件,并且可以保护Floquet微动过程中的动力学斯格明子结构.According to the recent experimental progress of simulating energy band topology and dynamic quantum phase transitions(DQPTs)in ultracold atomic systems,we develop a periodically driven one-dimensional(1D)Raman lattice system to simulate dynamic topological phenomena.By utilizing amplitude-periodically modulated Raman beams to couple the{^(1)S_(0),^(3)P_(1)}manifolds of alkaline-earth-like atoms^(171)Yb,we can realize the desired periodically driven Raman lattice.Utilizing the single-band,tight-binding Hamiltonian of the timeperiodic system,we analytically determine the effective Floquet Hamiltonian and the micromotion operator.These allow us to investigate the conditions under which Floquet dynamic quantum phase transitions and dynamic skyrmion structures emerge at any driving frequency in the 1D Raman lattice.When the corresponding vector trajectory of the effective Floquet Hamiltonian has a non-zero winding number(v≠0),the system exhibits both Floquet dynamic quantum phase transitions and dynamic skyrmion structures.For v=0,Floquet dynamic quantum phase transitions may still occur,but dynamic skyrmion structures will definitely disappear.Therefore,the topologically nontrivial nature of the effective Floquet Hamiltonian is a sufficient but not necessary condition for the onset of the Floquet dynamic quantum phase transitions.But it is a necessary and sufficient condition for the onset of the dynamical skyrmion structures.

关 键 词：拓扑相 动力学量子相变 超冷原子 拉曼晶格 

分 类 号：O413[理学—理论物理]