Quantum Discord and its distribution in multipartite systems

Chandrashekar Radhakrishnan, Mathieu Lauriere, Tim Byrnes

Published 2019-09-18Version 1

A generalization of quantum discord for multipartite systems is proposed. A key feature of our formulation is its consistency with the conventional definition of discord in bipartite systems. It is by construction zero only for systems with classically correlated subsystems and is a non-negative quantity, giving a measure of the total quantum correlations in the multipartite system. We show that the discord can be decomposed into contributions resulting from changes induced by quantum correlation breaking measurements in the conditional mutual information and tripartite mutual information. The former gives a measure of the bipartite quantum correlations and is a non-negative quantity, while the latter is related to the monogamy of quantum correlations.