Bose Condensation of Photons Thermalized via Laser Cooling of Atoms

TL;DR

This paper demonstrates theoretically that photons can undergo Bose-Einstein condensation during laser cooling of atoms inside a cavity, leveraging a photon thermalization mechanism that conserves photon number.

Contribution

It introduces a novel scenario where photon BEC is achieved via laser cooling, expanding the understanding of photon condensation in atomic systems.

Findings

Photon BEC can be realized during laser cooling in a cavity.

The mechanism involves effective photon number conservation.

Applicable to two-level alkaline earth atoms.

Abstract

A Bose-Einstein condensate (BEC) is a quantum phase of matter achieved at low temperatures. Photons, one of the most prominent species of bosons, do not typically condense due to the lack of a particle number-conservation. We recently described a photon thermalization mechanism which gives rise to a grand canonical ensemble of light with effective photon number conservation between a subsystem and a particle reservoir. This mechanism occurs during Doppler laser cooling of atoms where the atoms serve as a temperature reservoir while the cooling laser photons serve as a particle reservoir. Here we address the question of the possibility of a BEC of photons in this laser cooling photon thermalization scenario and theoretically demonstrate that a Bose condensation of photons can be realized by cooling an ensemble of two-level atoms (realizable with alkaline earth atoms) inside a Fabry-Perot cavity.