Quantifying quantum non-Markovianity via one-shot generalised mutual information

Abstract

We propose an alternative non-Markovianity measure of open quantum systems, which is based on max-information. The max-information is a one-shot generalization of the mutual information derived from the max-relative entropy. This operational interpretation provides a new site for viewing the non-Markovian process. As applications, some typical noisy channels have been investigated: for phase damping and amplitude damping channels, non-Markovianity measure based on max-information is equivalent to the three previous non-Markovianity measures, i.e. the measures based on the distinguishability, entanglement of environment and the mutual information. For the random unitary channel, the proposed measurement in the witness of Markovianity is equivalent to the measures based on quantum trace distance and thus overlaps partly with the measurement based on the mutual information. It shows that max-information may be a better candidate for correlation-based measurement of non-Markovian than the mutual information.