Quantum correlations for bipartite continuous-variable systems

Abstract

Two quantum correlations Q and $$Q_\mathcal P$$ for $$(m+n)$$ -mode continuous-variable systems are introduced in terms of average distance between the reduced states under the local Gaussian positive operator-valued measurements, and analytical formulas of these quantum correlations for bipartite Gaussian states are provided. It is shown that the product states do not contain these quantum correlations, and conversely, all $$(m+n)$$ -mode Gaussian states with zero quantum correlations are product states. Generally, $$Q\ge Q_{\mathcal P}$$ , but for the symmetric two-mode squeezed thermal states, these quantum correlations are the same and a computable formula is given. In addition, Q is compared with Gaussian geometric discord for symmetric squeezed thermal states.