We apply spin-squeezing techniques to identify and quantify highly multi-partite photonic entanglement in polarization-squeezed light. We consider a practical single-mode scenario, and find that Wineland-criterion polarization squeezing implies entanglement of a macroscopic fraction of the total photons. A Glauber-theory computation of the observable N-photon density matrix, with N up to 100, finds that N-partite entanglement is observable despite losses and without post-selection. We estimate that existing detectors could observe ∼1000-partite entanglement from a few dB of polarization squeezing.
@article{arxiv.1304.2527,
title = {Extreme spin squeezing for photons},
author = {Morgan W. Mitchell and Federica A. Beduini},
journal= {arXiv preprint arXiv:1304.2527},
year = {2014}
}