Complete bi-partite CV entanglement characterization viaCovariance Matrix measurement.

摘要

We report the first complete experimental reconstruction of the covariance matrix (CM) relative to a bi-partitecontinuous variable (CV) entangled state outing a non degenerate optical parametric oscillator (OPO) belowthreshold. The covariance matrix CM has been reconstructed following the method reported in V. D'Auria etal., J. Opt. B 7, S750 (2005). The two entangled beams (signal (a) and idler (b)) are produced by a by acontinuous wave (CW) optical parametric oscillator (OPO) via type-II (same frequency but with orthogonalpolarizations), phase matching and working below threshold. Our experimental setup makes use of a singlehomodyne detector and of a compact source of entangled beams. The quadratures values and other relevantquantities are reconstructed by quantum tomography, without making any a priori assumption on the state underevalutation.