Experimental quantification of the entanglement of noisy twin beams

TL;DR

This paper experimentally investigates how external noise affects the entanglement of twin beams, using various quantifiers like non-classicality depths and negativity, providing insights into entanglement degradation.

Contribution

It introduces a comprehensive experimental approach to quantify entanglement loss in noisy twin beams using multiple criteria and analysis methods.

Findings

Entanglement decreases with increasing external noise.

Non-classicality depths effectively quantify entanglement reduction.

Negativity provides an additional measure of entanglement degradation.

Abstract

Gradual loss of the entanglement of a twin beam containing around 25 photon pairs with the increasing external noise is experimentally investigated. The entanglement is quantified by the non-classicality depths and the non-classicality counting parameters related to several non-classicality criteria. The reduction of intensity moments of the analyzed multi-mode twin beams to single-mode ones allows to determine the negativity as another quantifier of the entanglement. Both the raw photocount histograms and the reconstructed photon-number distributions are analyzed in parallel.