Dynamical correlation functions and the quantum Rabi model
F. Alexander Wolf, Fabio Vallone, Gustavo E. Romero, Marcus Kollar, E. Solano, Daniel Braak · Physical Review A · 2013
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-coupling, and the 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.