Bonn 2025 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 12: Poster – Cold Atoms and Molecules, Matter Waves (joint session Q/A/MO)
MO 12.19: Poster
Dienstag, 11. März 2025, 14:00–16:00, Tent
Polarization properties of Photon Bose Einstein Condensates — •Sven Enns1, Julian Schulz1, Kirankumar Karkihalli Umesh2, Frank Vewinger2, and Georg von Freymann1,3 — 1Physics Department and Research Center OPTIMAS, RPTU Kaiserslautern Landau, Germany — 2Institut für Angewandte Physik, Universität Bonn, Germany — 3Fraunhofer Institute for Industrial Mathematics ITWM, Kaiserslautern, Germany
We experimentally investigate properties of harmonically trapped photon gases in a dye-filled microcavity. Specifically, we analyze the polarization of thermal and condensed light and their dependence on the polarization of the pump beam. Our experimental setup enables the creation of arbitrary polarization states on the Poincaré sphere for the pump beam. Additionally, the measurement basis can be switched from linear to circular polarization allowing for a proper evaluation of the photon gas's polarization by measuring fractions of two orthogonal polarization states simultaneously. In contrast to previous setups, the dye solution is pumped through the cavity mirrors and the pump beam coincides with the optical axis of the resonator so that no spontaneous symmetry breaking is expected. In agreement with previous theoretical work [1], there is a remarkable increase of the polarization strength above the condensation threshold for a linear polarized pump. While the polarization of the condensate aligns with that of the pump beam, a circularly polarized condensate cannot be obtained. Below the condensation threshold, the photon gas stays unpolarized.
[1] R. I. Moodie, P. Kirton, and J. Keeling, Phys. Rev. A 96 (2017).
Keywords: quantum gases; photon Bose-Einstein condensate; condensate polarization