Absorption of correlated photons by dense and cold atomic clouds

Abstract

Dense atomic clouds represent an interesting platform for studying collective effects, such as super- and subradiance. On the other hand, the correlated emission and absorption of entangled photons has important applications in quantum technologies, in particular, quantum communication protocols. Generally, twin photons are emitted (or absorbed) by single atoms exploiting an atomic multilevel structure. The question we would like to address in this research project is, theoretically and experimentally, is whether twin photons can be collectively absorbed by two atoms provided they are close enough to interact with each other via dipolar forces. The invited visiting researcher has recognized experience in the production of twin photons, and published research on the consequences of non-classical correlations for two-photons absorption by a single quantum absorber. On the other hand, our experiment in São Carlos is already capable of producing very dense clouds of ultracold strontium atoms. Together with the researcher we will try to find out, whether and in which parameter regime our system should be able demonstrate cooperative absorption of correlated photons, and what could be unambiguous experimental signatures. (AU)