Quantum correlations from classical Gaussian correlations

Andrei Yu. Khrennikov

Alessia Allevi, Maria Bondani, Matteo G. A. Paris +1 more

CHRISTOF WETTERICH

Su-Yong Lee, Yonggi Jo, Jihwan Kim +3 more

We study the characteristics of two-mode classical correlation in Gaussian regime, which is produced by impinging a thermal state into a beam splitter. It is explicitly investigated how a measurement on one mode affects the other. The result enables the distinction between classical and quantum correlations. Then, we show how classically correlated states are advantageous in target detection, specifically for an asymmetric classical correlation with different mean photon numbers in the signal and idler modes. Under on-off detection, the classically correlated states significantly outperform quantum correlated states as the environmental thermal mean photon number increases. Furthermore, we demonstrate the advantage of local Gaussian operations in the target detection.

Gerardo Adesso, Animesh Datta

Quantum discord, a measure of genuinely quantum correlations, is generalized to continuous variable systems. For all two-mode Gaussian states, we calculate analytically the quantum discord and a related measure of classical correlations, solving an optimization over all Gaussian measurements. Almost all two-mode Gaussian states are shown to have quantum correlations, while for separable states, the discord is smaller than unity. For a given amount of entanglement, it admits tight upper and lower bounds. Via a duality between entanglement and classical correlations, we derive a closed formula for the Gaussian entanglement of formation of a family of three-mode Gaussian states.

Guido Bellomo, A. P. Majtey, Angel Ricardo Plastino +1 more