In this paper, we study measures of quantum non-Markovianity based on the conditional mutual information. We obtain such measures by considering multiple parts of the total environment such that the conditional mutual information can be defined in this multipartite setup. The benefit of this approach is that the conditional mutual information is closely related to recovery maps and Markov chains; we also point out its relations with the change in distinguishability. We study along the way the properties of leaked information, which is the conditional mutual information that can be back flowed, and we use this leaked information to show that the correlated environment is necessary for the nonlocal memory effect.

• Received 18 April 2021
• Accepted 1 September 2021

DOI:https://doi.org/10.1103/PhysRevA.104.032212