Population inversion of driven two-level systems in a structureless bath

TL;DR

This paper derives a master equation for a driven double-dot system coupled to an unstructured phonon bath, revealing that bath-mediated photon absorption can induce population inversion under strong driving, aligning with recent experiments.

Contribution

It introduces a new master equation model that captures bath-mediated photon absorption leading to population inversion in driven double-dot systems.

Findings

Bath-mediated photon absorption dominates at strong driving.

Population inversion can be achieved in the double-dot system.

Results align with recent experimental observations.

Abstract

We derive a master equation for a driven double-dot damped by an unstructured phonon bath, and calculate the spectral density. We find that bath mediated photon absorption is important at relatively strong driving, and may even dominate the dynamics, inducing population inversion of the double dot system. This phenomenon is consistent with recent experimental observations.