Full characterization of Gaussian bipartite entangled states by a single homodyne detector

TL;DR

This paper demonstrates a method to fully characterize Gaussian bipartite entangled states generated by an optical parametric oscillator using a single homodyne detector, enabling comprehensive analysis without prior assumptions.

Contribution

The authors introduce a single-homodyne detection scheme for complete covariance matrix reconstruction of bipartite Gaussian states, simplifying and improving state characterization.

Findings

Successful full reconstruction of Gaussian entangled states

Efficient evaluation of purity, entanglement, and nonclassical correlations

Single homodyne detection proves to be a robust and convenient method

Abstract

We present the full experimental reconstruction of Gaussian entangled states generated by a type--II optical parametric oscillator (OPO) below threshold. Our scheme provides the entire covariance matrix using a single homodyne detector and allows for the complete characterization of bipartite Gaussian states, including the evaluation of purity, entanglement and nonclassical photon correlations, without a priori assumptions on the state under investigation. Our results show that single homodyne schemes are convenient and robust setups for the full characterization of OPO signals and represent a tool for quantum technology based on continuous variable entanglement.