Purity as a witness for initial system-environment correlations in open-system dynamics

TL;DR

This paper demonstrates that the evolution of purity in a two-level atom system can reveal initial correlations with the environment, especially under strong coupling, and extends this analysis to two atoms and their correlations.

Contribution

It introduces the use of purity dynamics as a witness for initial system-environment correlations in open quantum systems, including multi-atom scenarios.

Findings

Purity dynamics can identify initial correlations under strong coupling.

The method distinguishes different initial correlated states.

Analysis of quantum and classical correlations complements purity findings.

Abstract

We study the dynamics of a two-level atom interacting with a Lorentzian structured reservoir considering initial system-environment correlations. It is shown that under strong system-reservoir coupling the dynamics of purity can determine whether there are initial correlations between system and environment. Moreover, we investigate the interaction of two two-level atoms with the same reservoir. In this case, we show that besides determining if there are initial system-environment correlations, the dynamics of the purity of the atomic system allows the identification of the distinct correlated initial states. In addition, the dynamics of quantum and classical correlations is analyzed.