Fluctuation-Dissipation relation of a grand-canonical photon Bose-Einstein condensate

ORAL

Abstract

In thermal equilibrium, fluctuations of the particle number are related to the isothermal compressibility and the thermal energy kBT. This relation has been observed in a variety of systems ranging from Brownian particles to quantum gases, but not yet in Bose-Einstein condensates despite these systems are intrinsically in thermal equilibrium. Here, we experimentally investigate the fluctuation-dissipation relation in a Bose-Einstein condensate of photons realized in a dye-microcavity. The photon gas is coupled to a reservoir of dye molecular excitations, which serve both as a heat bath and a particle reservoir. Our measurements demonstrate a good agreement with the expected ratio of statistical number fluctuations and compressibility for a thermalized photon gas system following the flucutation-dissipation theorem.

*We acknowledge support by the DFG within SFB/TR 185 (277625399) and the Cluster of Excellence ML4Q (EXC 2004/1–390534769), the EU within the Quantum Flagship project PhoQuS, and the DLR with funds provided by the BMWi (50WM1859).

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Publication: Öztürk, Fahri Emre, et al. "Fluctuation-dissipation relation of a grand-canonical photon Bose-Einstein condensate." In preparation.
Öztürk, Fahri Emre, et al. "Observation of a non-Hermitian phase transition in an optical quantum gas." Accepted, Science (2021).
Ozturk, Fahri Emre, et al. "Fluctuation dynamics of an open photon Bose-Einstein condensate." Physical Review A 100.4 (2019): 043803.

Presenters

  • Fahri Emre E Öztürk

    • Univ Bonn
    • University of Bonn, Institute of Applied Physics

Authors

  • Fahri Emre E Öztürk

    • Univ Bonn
    • University of Bonn, Institute of Applied Physics

  • Frank Vewinger

    • Univ Bonn
    • University of Bonn, Institute of Applied Physics
    • Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115 Bonn, Germany

  • Julian Schmitt

    • Univ Bonn
    • University of Bonn, Institute of Applied Physics
    • Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115 Bonn, Germany

  • Martin Weitz

    • Univ Bonn
    • University of Bonn, Institute of Applied Physics
    • Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115 Bonn, Germany
    • Bonn