Bose-Einstein Condensation of Photons in a Microscopic Optical Resonator: Towards Photonic Lattices and Coupled Cavities

TL;DR

This paper reports the observation of Bose-Einstein condensation of photons in a microscopic optical resonator at room temperature, highlighting potential applications in quantum many-body photonic systems.

Contribution

It presents experimental evidence of photon Bose-Einstein condensation in a small optical cavity filled with dye solution, a novel setup for room-temperature photon condensates.

Findings

Photon BEC observed in microscopic cavity at room temperature

Potential for creating quantum many-body states with photon condensates

Discussion of applications in photonic lattices and Josephson devices

Abstract

Bose-Einstein condensation has in the last two decades been observed in cold atomic gases and in solid-state physics quasiparticles, exciton-polaritons and magnons, respectively. The perhaps most widely known example of a bosonic gas, photons in blackbody radiation, however exhibits no Bose-Einstein condensation, because the particle number is not conserved and at low temperatures the photons disappear in the system's walls instead of massively occupying the cavity ground mode. This is not the case in a small optical cavity, with a low-frequency cutoff imprinting a spectrum of photon energies restricted to values well above the thermal energy. The here reported experiments are based on a microscopic optical cavity filled with dye solution at room temperature. Recent experiments of our group observing Bose-Einstein condensation of photons in such a setup are described. Moreover, we discuss some possible applications of photon condensates to realize quantum manybody states in periodic photonic lattices and photonic Josephson devices.