Observation of three-body correlations for photons coupled to a Rydberg superatom

TL;DR

This paper demonstrates the experimental observation of three-photon correlations mediated by a Rydberg superatom, revealing complex quantum interactions and validating a theoretical model of photon-superatom coupling.

Contribution

It provides the first experimental evidence of three-photon correlations via a Rydberg superatom and introduces an exactly solvable model for interpreting these quantum phenomena.

Findings

Clear signatures of three-photon correlations observed

Good agreement with a quantitative superatom model

Interpretation via bound and scattering states

Abstract

We report on the experimental observation of non-trivial three-photon correlations imprinted onto initially uncorrelated photons through interaction with a single Rydberg superatom. Exploiting the Rydberg blockade mechanism, we turn a cold atomic cloud into a single effective emitter with collectively enhanced coupling to a focused photonic mode which gives rise to clear signatures in the connected part of the three-body correlation function of the out-going photons. We show that our results are in good agreement with a quantitative model for a single, strongly coupled Rydberg superatom. Furthermore, we present an idealized but exactly solvable model of a single two-level system coupled to a photonic mode, which allows for an interpretation of our experimental observations in terms of bound states and scattering states.