Squeezing based analytical variational method for the biased quantum Rabi model in the ultrastrong coupling regime
Weijie Xie, Bin-Bin Mao, Guangzhuo Li, Weihang Wang, Chen Sun, Yimin Wang, Wen‐Long You, Maoxin Liu · Journal of Physics A Mathematical and Theoretical · 2019
Abstract In order to obtain the ground state of the biased quantum Rabi model in the ultrastrong coupling regime, a generalized squeezing rotating-wave approximation method including the displacement and the squeezing transformations is proposed in this work. While considering the deformation of the oscillator state, our method evidently improves the generalized variational method. The analyses of a few physical quantities show that our method works well especially in the ultrastrong coupling and large atomic frequency regime.