On the non-Markovianity of quantum semi-Markov processes

TL;DR

This paper investigates the non-Markovian behavior of quantum semi-Markov processes using a new measure of memory, revealing that these processes can exhibit memory effects even when they are CP-divisible, and provides an operational interpretation.

Contribution

It introduces a unified quantification of non-Markovianity applicable to quantum semi-Markov processes, highlighting their memory effects in CP-divisible regimes and offering an operational perspective.

Findings

Quantum semi-Markov processes exhibit memory effects even when CP-divisible.

The proposed measure unifies the description of divisible and indivisible channels.

An operational meaning of non-Markovianity in semi-Markov processes is established.

Abstract

The non-Markovianity of the stochastic process called the quantum semi-Markov (QSM) process is studied using a recently proposed quantification of memory based on the deviation from semigroup evolution, that provides a unified description of divisible and indivisible channels. This is shown to bring out the property of QSM processes to exhibit memory effects even in the CP-divisible regime, in agreement with an earlier result. An operational meaning to the non-Markovian nature of semi-Markov processes is also provided.