Hannover 2020 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 49: Quantum gases (Miscellaneous)
Q 49.4: Talk
Thursday, March 12, 2020, 15:00–15:15, e214
Observation of a non-equilibrium phase transition in the second order coherence of a Bose-Einstein condensate of photons — •Fahri Emre Ozturk1, Tim Lappe2, Göran Hellmann1, Frank Vewinger1, Julian schmitt3, Jan Klaers4, Hans Kroha2, and Martin Weitz1 — 1Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, D-53115 Bonn — 2Physikalisches Institut and Bethe Center for Theoretical Physics, Universität Bonn, Nussallee 12, 53115 Bonn, Germany — 3Present address:Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom — 4Present address: Complex Photonic Systems (COPS), MESA+ Institute for Nanotechnology, University of Twente, 7522 NB Enschede, The Netherlands
Bose-Einstein condensates have been realized with cold atomic gases, exciton-polaritons and more recently with photons in dye-filled optical microcavities. In the latter system, grand canonical Bose-Einstein condensation has been demonstrated with enhanced statistical number fluctuations in the condensed state. Here we report on the observation of a transition between an oscillatory and a bi-exponential phase of the second order coherence of the condensate. The experiments are performed in a dye-filled optical microcavity at conditions very close to thermal equilibrium, with pumping and loss resulting in time-reversal symmetry breaking. The results show that photon Bose-Einstein condensates in a part of the phase diagram are separated by a phase transition from the non-equilibrium phenomenon of lasing.