Simulating Dicke like superradiance with classical light sources

TL;DR

This paper demonstrates that classical light sources can mimic Dicke superradiance patterns through intensity correlation measurements, revealing a deep connection between classical and quantum optical phenomena.

Contribution

It establishes a link between classical light sources and quantum superradiance by analyzing higher-order intensity correlations and measurement-induced effects.

Findings

Classical sources can produce superradiant emission patterns.

Photon detection induces quantum path superpositions similar to superradiance.

A compact functional for arbitrary order intensity correlations is derived.

Abstract

In this paper we investigate the close relationship between Dicke superradiance, originally predicted for an ensemble of two-level atoms in entangled states, and the Hanbury Brown and Twiss effect, initially established in astronomy to determine the dimensions of classical light sources like stars. By studying the state evolution of the fields produced by classical sources -- defined by a positive Glauber-Sudarshan P function -- when recording intensity correlations of higher order in a generalized Hanbury Brown and Twiss setup we find that the angular distribution of the last detected photon, apart from an offset, is identical to the superradiant emission pattern generated by an ensemble of two-level atoms in entangled symmetric Dicke states. We show that the phenomenon derives from projective measurements induced by the measurement of photons in the far field of the sources and the permutative superposition of quantum paths identical to those leading to superradiance in the case of single photon emitters. We thus point out an important similarity between classical sources and quantum emitters upon detection of photons if the particular photon source remains unknown. We finally present a compact result for the characteristic functional which generates intensity correlations of arbitrary order for any kind of light sources.