Dynamics of a qubit coupled to a broadened harmonic mode at finite detuning

TL;DR

This paper analyzes the dynamics of a qubit strongly coupled to a broadened harmonic oscillator mode, providing analytical solutions at finite detuning and temperature, and comparing them with numerical results.

Contribution

It introduces an analytical approach to study qubit-oscillator dynamics at finite detuning and temperature, extending previous models to broadened modes with high Q-factors.

Findings

Multiple oscillation frequencies observed due to entanglement.

Analytical solutions agree well with numerical predictions.

Effective mapping to a spin-boson model with peaked spectral density.

Abstract

We study the dynamics of a symmetric two-level system strongly coupled to a broadened harmonic mode. Upon mapping the problem onto a spin-boson model with peaked spectral density, we show how analytic solutions can be obtained, at arbitrary detuning and finite temperatures, in the case of large Q-factors of the oscillator. In general {\em two} or more oscillation frequencies of the two-level particle are observed as a consequence of the entanglement with the oscillator. Our approximated analytical solution well agrees with numerical predictions obtained within the non-interacting blip approximation.