Optical nonclassicality test based on third-order intensity correlations

TL;DR

This paper introduces a nonclassicality test based on third-order intensity correlations in a three-mode Bell interferometer, demonstrating that certain correlation revivals indicate inherently quantum light sources with sub-Poissonian statistics.

Contribution

It develops a new nonclassicality criterion for three-light-field interference, linking correlation revivals to quantum properties and collective phase effects, extending understanding beyond previous experiments.

Findings

Correlation revival cannot be explained classically

Revival indicates highly sub-Poissonian photon statistics

Supports nonclassicality of previously studied experimental setups

Abstract

We develop a nonclassicality criterion for the interference of three delayed, but otherwise identical, light fields in a three-mode Bell interferometer. We do so by comparing the prediction of quantum mechanics with those of a classical framework in which independent sources emit electric fields with random phases. In particular, we evaluate third-order correlations among output intensities as a function of the delays, and show how the presence of a correlation revival for small delays cannot be explained by the classical model of light. The observation of a revival is thus a nonclassicality signature, which can be achieved only by sources with a photon-number statistics that is highly sub-Poissonian. Our analysis provides strong evidence for the nonclassicality of the experiment discussed by Menssen et al. [Menssen et al., Phys. Rev. Lett, 118, 153603 (2017)], and shows how a collective "triad" phase affects the interference of any three or more light fields, irrespective of their quantum or classical character.