Dressed Relaxation and Dephasing in a Strongly Driven Two-Level system

TL;DR

This paper develops a theory describing relaxation and dephasing in a strongly driven two-level quantum system, using dressed states to explain complex dynamics and matching experimental results in superconducting qubits.

Contribution

It introduces a novel theoretical framework that accounts for dressing effects on relaxation and dephasing in strongly driven two-level systems, validated by experimental data.

Findings

Good quantitative agreement between theory and experiment

Identification of population inversion signatures

Rich dynamical behavior due to competing processes

Abstract

We study relaxation and dephasing in a strongly driven two-level system interacting with its environment. We develop a theory which gives a straightforward physical picture of the complex dynamics of the system in terms of dressed states. In addition to the dressing of the energy diagram, we describe the dressing of relaxation and dephasing. We find a good quantitative agreement between the theoretical calculations and measurements of a superconducting qubit driven by an intense microwave field. The competition of various processes leads to a rich structure in the observed behavior, including signatures of population inversion.