Multi-photon nonclassical correlations in entangled squeezed vacuum states

TL;DR

This paper demonstrates that macroscopic Bell states, with around a million photons per pulse, exhibit polarization entanglement and violate separability criteria, confirmed through photon-number correlation measurements and entanglement witnesses.

Contribution

It provides experimental evidence of polarization entanglement in bright, macroscopic squeezed vacuum states and explores their symmetry properties under local polarization transformations.

Findings

Violation of separability criteria confirms entanglement.

Macroscopic Bell states are polarization entangled.

States exhibit symmetry under local polarization transformations.

Abstract

Photon-number correlation measurements are performed on bright squeezed vacuum states using a standard Bell-test setup, and quantum correlations are observed for conjugate polarization-frequency modes. We further test the entanglement witnesses for these states and demonstrate the violation of the separability criteria, which infers that all the macroscopic Bell states, containing typically $10^6$ photons per pulse, are polarization entangled. The study also reveals the symmetry of macroscopic Bell states with respect to local polarization transformations.