An experimental investigation of criteria for continuous variable entanglement

Motivated by previous observations on the characterization of entangled optical beams, this paper presents a characterization of entanglement not only in terms of inseparability, but also by its mixedness. The entanglement is presented on a diagram of the average sideband photon number required to generate the entanglement (a property synonymous to inseparability) versus the average number of excess sideband photons, as deduced from the measured values of the quadrature variances. The efficacy contours of some common quantum information protocols are also displayed.