摘要

In this paper, we propose a theoretical scheme to detect the emitter-resonator coupling strength in the ultra-strong-coupling regime in the quantum Rabi model via introducing an auxiliary resonator. We demonstrate the total system as a two-mode Rabi model and obtain the ground state by the transformed rotating-wave approximation, which is shown to be superior to the usually applied rotating-wave approximation. Here, the coupling strength is detected by monitoring the average excitation number in the auxiliary resonator, and the sensitivity of the detection scheme is discussed analytically.