The quest for three-color entanglement: experimental investigation of new multipartite quantum correlations

TL;DR

This paper reports experimental exploration of quantum correlations in a three-color optical system, revealing new correlations and noise challenges, advancing toward demonstrating tripartite entanglement.

Contribution

It introduces new experimental observations of quantum correlations involving pump, signal, and idler fields, and discusses classical noise effects hindering tripartite entanglement.

Findings

Observed new quantum correlations among pump, signal, and idler fields.

Identified classical noise that limits tripartite entanglement demonstration.

Results approach the threshold for three-color entanglement.

Abstract

We experimentally investigate quadrature correlations between pump, signal, and idler fields in an above-threshold optical parametric oscillator. We observe new quantum correlations among the pump and signal or idler beams, as well as among the pump and a combined quadrature of signal and idler beams. A further investigation of unforeseen classical noise observed in this system is presented, which hinders the observation of the recently predicted tripartite entanglement. In spite of this noise, current results approach the limit required to demonstrate three-color entanglement.