Phase diffusion in a Bose-Einstein condensate of light

TL;DR

This paper investigates phase diffusion in a light Bose-Einstein condensate within a dye-filled microcavity, proposing an interference experiment to observe phase spreading influenced by quantum, thermal, and dissipative effects.

Contribution

It introduces a method to observe phase diffusion in photon BECs and models the phase dynamics using a stochastic equation considering various fluctuations and dissipation.

Findings

Interference patterns reveal phase diffusion effects.

Quantum and thermal fluctuations significantly impact phase stability.

Dissipative effects due to dye influence the condensate's phase dynamics.

Abstract

We study phase diffusion in a Bose-Einstein condensate of light in a dye-filled optical microcavity, i.e., the spreading of the probability distribution for the condensate phase. To observe this phenomenon, we propose an interference experiment between the condensed photons and an external laser. We determine the average interference patterns, considering quantum and thermal fluctuations as well as dissipative effects due to the dye. Moreover, we show that a representative outcome of individual measurements can be obtained from a stochastic equation for the global phase of the condensate.