Fidelity-based unitary operation-induced quantum correlation for continuous-variable systems

摘要

We propose a measure of nonclassical correlation N-F(G) in terms of local Gaussian unitary operations based on square of the fidelity F for bipartite continuous-variable systems. This quantity is easier to be calculated or estimated and is a remedy for the local ancilla problem associated with the geometric measurement-induced nonlocality. A simple computation formula of N-F(G) for any (1 + 1)-mode Gaussian states is presented and an estimation of N-F(G) for any (n m)-mode Gaussian states is given. For any (1 1)-mode Gaussian states, N-F(G) does not increase after performing a local Gaussian channel on the unmeasured subsystem. Comparing N-F(G)(rho(AB)) in scale with other quantum correlations such as Gaussian geometric discord for two-mode symmetric squeezed thermal states reveals that N-F(G) is much better in detecting quantum correlations of Gaussian states.