Quantification of Continuous Variable Entanglement with only Two Types of Simple Measurements

Abstract

Here we propose an experimental set-up in which it is possible to measure the entanglement of a two-mode Gaussian state, be it pure or mixed, using only simple linear optical devices. After a proper unitary manipulation of the two-mode Gaussian state only number and purity measurements of just one of the modes suffice to give us a complete and exact knowledge of the state's entanglement.Comment: v1: 4 pages, 1 figure, RevTex4; v2: Title and abstract changed, new discussion paragraph added; v3: published versio