Seminarium Optyczne

Photons were the first bosons to be considered under the quantum statistics known today as the Bose-Einstein statistics. However, they were one of the most recent quantum gases to undergo Bose-Einsteincondensation in a controlled environment, which was achieved recently in a microcavity filled with a 6Grhodamine solution [1]. Since these pioneering observations, the principle of light thermalisation andcondensation in optical cavities has been anticipated to be a much more common phenomenon. In this talk, Iwill present our most recent results on the Bose-Einstein condensation of photons in a well-knownsemiconductor device, the vertical-cavity surface-emitting laser (VCSEL). We measured a Bose-Einsteintype of behaviour when crossing the critical phase-space density and observed a thermalised distribution ofphotons, equilibrated to temperatures lower than those of the device. Nevertheless, the measuredspectroscopic and caloric properties show all predicted effects for a Bose-Einstein condensate phasetransition in thermal equilibrium. I will discuss our observations in context of a driven-dissipativenonequilibrium Bose-Einstein condensation phenomenon [2].[1] Klaers, J. et al., Nature 468, 545–8 (2010).[2] Shishkov, V. Y. et al., Phys. Rev. Lett. 128, 065301 (2022)