Dresden 2011 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 57: Poster 3: Quantengase, Ultrakalte Atome, Ultrakalte Moleküle, Materiewellen Optik, Präzisionsmessungen, Metrologie

Q 57.10: Poster

Donnerstag, 17. März 2011, 16:30–19:30, P1

Bose-Einstein condensation of a two-dimensional photon gas and prospects on its realization in solid-state materials — •Julian Schmitt, Jan Klaers, Frank Vewinger, and Martin Weitz — Institut für Angewandte Physik (IAP), Universität Bonn

Bose-Einstein condensation has been experimentally demonstrated in several physical systems, including cold atomic gases and solid-state quasiparticles. Owing to its vanishing chemical potential blackbody radiation does not collectively occupy the lowest energy mode when the temperature is lowered - but instead the photons disappear in the cavity walls. We describe a thermalized two-dimensional photon gas with a freely adjustable chemical potential based on a dye-filled microresonator. Thermalization to the temperature of the resonator is achieved by photon scattering off the dye molecules, and the cavity mirrors provide both an effective photon mass and a confining harmonic potential. This allows for Bose-Einstein condensation of photons, which is experimentally observed at sufficiently high photon densities. In more recent experiments, we have realized a thermalized photon gas in a solid state system. Dye molecules embedded in polymeric host matrices allow for multiple emission and reabsorption processes of the photons driving the system to thermal equilibrium, with the occupation of transversal modes being Boltzmann-like. In correspondence to our experiments carried out on the liquid dye solution, a spatial concentration effect of the light to the centre of the confining potential is observed. However, the experiment reveals a sensitive dependence of the spatial redistribution extent on the fluorescence quantum yield of the dye molecules.