Transmission spectra of the driven, dissipative Rabi model in the USC regime

TL;DR

This paper provides a theoretical analysis of the transmission spectra of a driven, dissipative qubit-resonator system in the ultrastrong coupling regime, revealing how dissipation and driving influence spectral features and system behavior.

Contribution

It introduces a detailed theoretical framework for understanding the driven dissipative Rabi model in the ultrastrong coupling regime, relevant for superconducting circuit QED.

Findings

Identification of resonant features and avoided crossings in the spectrum

Analysis of how dissipation and driving modify spectral properties

Quantification of the effects of detuning, coupling strength, and bath interaction

Abstract

We present theoretical transmission spectra of a strongly driven, damped, flux qubit coupled to a dissipative resonator in the ultrastrong coupling regime. Such a qubit-oscillator system, described within a dissipative Rabi model, constitutes the building block of superconducting circuit QED platforms. The addition of a strong drive allows one to characterize the system properties and study novel phenomena, leading to a better understanding and control of the qubit-oscillator system. In this work, the calculated transmission of a weak probe field quantifies the response of the qubit, in frequency domain, under the influence of the quantized resonator and of the strong microwave drive. We find distinctive features of the entangled driven qubit-resonator spectrum, namely resonant features and avoided crossings, modified by the presence of the dissipative environment. The magnitude, positions, and broadening of these features are determined by the interplay among qubit-oscillator detuning, the strength of their coupling, the driving amplitude, and the interaction with the heat bath. This work establishes the theoretical basis for future experiments in the driven ultrastrong coupling regime and their impact to develop novel quantum technologies with superconducting circuits.