An analytical variational method for the biased quantum Rabi model in the ultra-strong coupling regime

报告题目：An analytical variational method for the biased quantum Rabi model in the ultra-strong coupling regime

报告人：刘卯鑫博士(北京邮电大学物理系)

报告时间：2019年7月12日9:30

报告地点：物理科技楼343

报告邀请人：董裕力

报告摘要：An analytical variational method for the ground state of the biased quantum Rabi model in the ultra-strong coupling regime is presented. This analytical variational method can be obtained by a unitary transformation or alternatively by assuming the form of ground state wave function. The key point of the method is to introduce a variational parameter λ, which can be determined by minimizing the energy functional. Using this method, we calculate physical observables with high accuracy in comparison with the numerical exact one. Our method evidently improves the results from the widely used general rotating-wave approximation (GRWA) in both qualitative and quantitative ways.