Exact Solutions to the Quantum Rabi-Stark Model Within Tunable Coherent States

作     者：You-Fei Xie Qing-Hu Chen 谢幼飞;陈庆虎

作者机构：Department of PhysicsZhejiang UniversityHangzhou310027China Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing210093China 

出 版 物：《Communications in Theoretical Physics》 (理论物理通讯（英文版）)

年 卷 期：2019年第71卷第5期

页      面：623-628页

核心收录：

学科分类：070207[理学-光学] 07[理学] 08[工学] 0803[工学-光学工程] 0702[理学-物理学] 

基　　金：Supported by the National Science Foundation of China under Grant Nos.11674285 and 11834005 

主　　题：extended coherent states exact eigenvalues first-order phase transitions spectral collapse 

摘      要：The quantum Rabi-Stark model, where the linear dipole coupling and the nonlinear Stark-like coupling is present on an equal footing, is studied within the tunable extended coherent states. The eigenvalues and eigenstates are therefore obtained exactly. Surprisingly, the entanglement entropy in the ground-state is found to jump suddenly with the coupling strength. The first-order quantum phase transition can be detected by level crossing of the ground state and the first excited state, which is however lacking in the original linear quantum Rabi model. Performing the first-order approximation in the present theory, we can derive closed-form analytical results for the ground-state. Interestingly, it agrees well with the exact solutions up to the ultra-strong coupling regime in a wide range of model parameters. The spectral collapses when the absolute value of the nonlinear coupling strength approaches to twice the cavity frequency is observed with the help of new solutions in the limits.