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 106 photons per pulse, are polarization entangled. The study also reveals the symmetry of macroscopic Bell states with respect to local polarization transformations.
@article{arxiv.1301.4471,
title = {Multi-photon nonclassical correlations in entangled squeezed vacuum states},
author = {Bhaskar Kanseri and Timur Iskhakov and Georgy Rytikov and Maria Chekhova and Gerd Leuchs},
journal= {arXiv preprint arXiv:1301.4471},
year = {2015}
}