Heidelberg 2015 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 62: Poster: Quantum Optics and Photonics III

Q 62.28: Poster

Donnerstag, 26. März 2015, 17:00–19:00, C/Foyer

Quantum Gases of Light in Variable Potentials — •David Dung, Dario Bashir-Elahi, Tobias Damm, Julian Schmitt, Christian Wahl, Frank Vewinger, Jan Klärs, and Martin Weitz — Institut für Angewandte Physik, Universität Bonn

Bose-Einstein condensation, the macroscopic ground state occupation of bosonic particles at low temperature and high density, has previously been observed for cold atomic gases and solid state quasiparticles. In recent work, our group has realized Bose-Einstein condensation of photons in a dye-filled optical microcavity. In this experiment, a number conserving thermalization process is achieved by multiple absorption and fluorescence processes of dye-molecules. The microcavity creates a confining potential, providing a suitable ground state and leading to a non-vanishing effective photon mass. Formally, the system is equivalent to a two-dimensional gas of trapped, massive bosons.

Here we report on recent work to create multiple BECs of photons in a single microcavity. The BECs are trapped in variable potentials that are induced by locally changing the refractive index inside the microcavity. In the experiment this is realized by focused laser light that heats an absorptive thin film near the mirror surface. A thermo-responsive polymer mixed with the dye solution will then undergo a phase-transition and thereby change the refractive index. Recently, we determined the range of depths and trapping frequencies one can adjust with this technique to create variable potentials for light. Moreover, we show efforts to observe tunneling of photons between lattice sides.