Floquet spectrum and universal dynamics of a periodically driven two-atom system  

作　　者：谢文柱 周正强 李轩 崔思淼 孙明远 Wenzhu Xie;Zhengqiang Zhou;Xuan Li;Simiao Cui;Mingyuan Sun(School of Science,Beijing University of Posts and Telecommunications,Beijing 100876,China)

机构地区：[1]School of Science,Beijing University of Posts and Telecommunications,Beijing 100876,China

出　　处：《Chinese Physics B》2024年第2期436-443,共8页中国物理B（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.12004049);the Fund of State Key Laboratory of IPOC(BUPT)(Grant Nos.600119525 and 505019124).

摘　　要：We investigate the Floquet spectrum and excitation properties of a two-ultracold-atom system with periodically driven interaction in a three-dimensional harmonic trap.The interaction between the atoms is changed by varying the s-wave scattering length in two ways,the cosine and the square-wave modulations.It is found that as the driving frequency increases,the Floquet spectrum exhibits two main features for both modulations,the accumulating and the spreading of the quasienergy levels,which further lead to different dynamical behaviors.The accumulation is associated with collective excitations and the persistent growth of the energy,while the spread indicates that the energy is bounded at all times.The initial scattering length,the driving frequency and amplitude can all significantly change the Floquet spectrum as well as the dynamics.However,the corresponding relation between them is valid universally.Finally,we propose a mechanism for selectively exciting the system to one specific state by using the avoided crossing of two quasienergy levels,which could guide preparation of a desired state in experiments.

关 键 词：Floquet spectrum universal dynamics two-atom system avoided crossing 

分 类 号：O562[理学—原子与分子物理]