Dynamical correlation functions and the quantum Rabi model

TL;DR

This paper analyzes the quantum Rabi model using an analytical approach to classify different coupling regimes and identifies a stationary entangled basis that describes the system's dynamics.

Contribution

It provides a quantitative criterion for distinguishing coupling regimes and introduces a stationary entangled basis for the entire dynamics of the model.

Findings

Classifies the Jaynes-Cummings, ultrastrong, and deep strong coupling regimes.

Identifies a stationary qubit-field entangled basis.

Provides insights into the dynamics across different coupling strengths.

Abstract

We study the quantum Rabi model within the framework of the analytical solution developed in Phys. Rev. Lett. 107,100401 (2011). In particular, through time-dependent correlation functions, we give a quantitative criterion for classifying two regions of the quantum Rabi model, involving the Jaynes-Cummings, the ultrastrong, and deep strong coupling regimes. In addition, we find a stationary qubit-field entangled basis that governs the whole dynamics as the coupling strength overcomes the mode frequency.