Correlated and Critical Phenomena in Multipartite Quantum Non-Markovianity

TL;DR

This paper investigates how interatomic distance and system size influence non-Markovian behavior in two-atom systems within a cavity, revealing critical transitions and the role of correlations in quantum memory effects.

Contribution

It introduces a non-singular measure of non-Markovianity and demonstrates critical phenomena and thresholds for memory effects based on system parameters.

Findings

Critical Markovian to non-Markovian transition at finite interatomic distance

Discontinuity in non-Markovianity as atoms become infinitely close

Non-Markovianity emerges when system size exceeds a critical threshold

Abstract

We study non-Markovianity in the exact dynamics of two two-level atoms in a resonant cavity. We find a critical behavior in the form of a Markovian to non-Markovian transition at a finite interatomic distance and a discontinuity in the limit of infinitely close atoms. Actually, in this highly correlated regime, we find that non-Markovianity always arises if the system size exceeds a critical threshold. To this end, a non-singular, additive non-Markovian measure with appropriate asymptotic behavior is formulated. These results show how inter-subsystem distance and system size can act as precise controls for modulating memory effects in multipartite open quantum systems.