Monogamy of quantum discord by multipartite correlations

Abstract

We introduce a monogamy inequality for quantum correlations, which implies that the sum of pairwise quantum correlations is upper limited by the amount of multipartite quantum correlations as measured by the global quantum discord. This monogamy bound holds either for pure or mixed quantum states provided that bipartite quantum discord does not increase under discard of subsystems. We illustrate the monogamy behavior for multipartite pure states with Schmidt decomposition as well as for $W$-GHZ mixed states. As a by-product, we apply the monogamy bound to investigate residual multipartite correlations.