Analytical solutions by squeezing to the anisotropic Rabi model in the nonperturbative deep-strong coupling regime

TL;DR

This paper introduces an analytical approach using generalized squeezing rotating-wave approximation to study the anisotropic Rabi model in the nonperturbative deep-strong coupling regime, aligning well with numerical results.

Contribution

It presents a novel analytical method for the anisotropic Rabi model in the nonperturbative deep-strong coupling regime, incorporating deformation effects via displaced-squeezed states.

Findings

Analytical energy levels match numerical results across coupling strengths.

Deformation effects improve the accuracy of the model.

Population dynamics validate the approach for npDSC regimes.

Abstract

A novel, unexplored nonperturbative deep-strong coupling (npDSC) achieved in superconducting circuits has been studied in the anisotropic Rabi model by the generalized squeezing rotating-wave approximation (GSRWA). Energy levels are evaluated analytically from the reformulated Hamiltonian and agree well with numerical ones under a wide range of coupling strength. Such improvement ascribes to deformation effects in the displaced-squeezed state presented by the squeezed momentum variance, which are omitted in the previous displaced state. The population dynamics confirm the validity of our approach for the npDSC strength. Our approach paves a way to the exploration of analysis in qubit-oscillator experiments for the npDSC strength by the displaced-squeezed state.