Memory effects in multipartite systems coupled by non-diagonal dephasing mechanisms

TL;DR

This paper analytically investigates memory effects in multipartite quantum systems with non-diagonal Markovian dephasing, revealing conditions for non-Markovianity and its relation to symmetry breaking and mixture representations.

Contribution

It provides an exact analytical characterization of quantum non-Markovianity in multipartite systems with non-diagonal dephasing, linking memory effects to symmetry breaking and mixture models.

Findings

Memory effects require broken time-reversal symmetry.

Departures from Markovianity can be represented as mixtures of Markovian dynamics.

Memory effects can occur without system-environment entanglement.

Abstract

The developing of (non-Markovian) memory effects strongly depends on the underlying system-environment dynamics. Here we study this problem in multipartite arrangements where all subsystems are coupled to each other by non-diagonal Markovian (Lindblad) dephasing mechanisms. Taking as system and environment arbitrary sets of complementary subsystems it is shown that both operational and non-operational approaches to quantum non-Markovianity can be characterized in an exact analytical way. Similarly to previous studies about dissipative-entanglement-generation in this kind of dynamics [Seif, Wang, and Clerk, Phys. Rev. Lett. 128, 070402 (2022)], we found that memory effects can only emerge when a time-reversal symmetry is broken. Nevertheless, it is also found that departures from Markovianity can equivalently be represented through a statistical mixture of Markovian dephasing dynamics, which does not involve any system-environment entanglement. Specific bipartite and multipartite dynamics exemplify the main general results.