Entanglement and nonclassicality: A mutual impression

TL;DR

This paper establishes a sufficient condition linking single-mode nonclassicality and bipartite entanglement via beam splitters, enabling entanglement generation from nonclassical states regardless of purity or temperature.

Contribution

It provides a novel criterion for converting nonclassicality into entanglement using beam splitters, applicable to high-temperature and large-particle systems.

Findings

Entanglement depends only on the nonclassicality of input/output states.

Entanglement persists in a lossy Mach-Zehnder interferometer unless both modes are fully lost.

The criterion applies regardless of state purity and separability.

Abstract

We find a sufficient condition to imprint the single-mode bosonic phase-space nonclassicality onto a bipartite state as modal entanglement and vice versa using an arbitrary beam splitter. Surprisingly, the entanglement produced or detected in this way depends only on the nonclassicality of the marginal input or output states, regardless of their purity and separability. In this way, our result provides a sufficient condition for generating entangled states of arbitrary high temperature and arbitrary large number of particles. We also study the evolution of the entanglement within a lossy Mach-Zehnder interferometer and show that unless both modes are totally lost, the entanglement does not diminish.