Dissipative two-level systems under ultrastrong off-resonant driving

TL;DR

This paper investigates the complex dissipative behaviors of a two-level quantum system under ultrastrong, off-resonant driving, revealing three distinct dynamical regimes and a nonmonotonic decay rate dependence influenced by relaxation and dephasing.

Contribution

It introduces a detailed analysis of dissipative dynamics in two-level systems under ultrastrong off-resonant driving, identifying new regimes and decay behaviors.

Findings

Identification of three distinct dynamical regimes

Prediction of Bessel-function-like decay rate dependence

Dependence of features on relaxation and dephasing rates

Abstract

We study the dissipative dynamics of a two-level system under ultrastrong driving when the frequency and strength of the exciting field exceed significantly the transition frequency. We find three qualitatively different regimes of such dynamics: 1) the collapse and revival of oscillations in the population difference, 2) the simple exponential decay of the oscillations resulting in their steady state with the finite amplitude, and 3) the steady-state stabilization of the equally populated levels. The nonmonotonic Bessel-function-like dependence on the driving strength is also predicted for the decay rate of these oscillations. The features of this dependence are determined by the relative rates of energetic relaxation and pure dephasing.