On the generation of entanglement from the interference of Gaussian states of light

Abstract

We address the interaction of two Gaussian states of light interfering at a balanced beam splitter and analyze the correlations exhibited by the resulting bipartite system. Nonlocal quantum correlations (entanglement) arise if and only if the fidelity between the two input Gaussian states falls under a threshold value depending only on their purities. In particular, our result clarifies the role of squeezing as a prerequisite for entanglement and provide a tool to optimize the generation of entanglement by passive devices.