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Q: Fachverband Quantenoptik und Photonik

Q 39: Photon BEC

Q 39.4: Vortrag

Mittwoch, 12. März 2025, 15:15–15:30, HS V

Field-theoretical description of driven-dissipative photon Bose-Einstein condensates — •Roman Kramer¹, Michael Kajan¹, and Johann Kroha^1,2 — ¹Physikalisches Institut, Universität Bonn — ²University of St. Andrews, United Kingdom

We formulate a Schwinger-Keldysh field theory to treat the non-Markovian dynamics of driven-dissipative quantum systems coupled to a reservoir. This is done by introduction of auxiliary particles, which assign an indiviual quantum field to each reservoir state, as developed in [1]. We apply the formalism to a driven-dissipative photon Bose-Einstein condensate (BEC) coupled to a reservoir of dye molecules with electronic and vibronic excitations in an optical microcavity, as observed experimentally in [2]. The emergence of a photon BEC is then achieved by inclusion of U(1) symmetry-broken photon fields, which thermalize due to coupling to the molecules described by auxiliary particles. We find that the condensed parts of the photon modes dynamically synchronize and form a single BEC. This formalism can be extended to multiple coupled cavities.

References:

[1] T. Bode, M. Kajan et al. Phys. Rev. Res. 6, 10.1103 (2024).

[2] J. Klaers, J. Schmitt, F. Vewinger et al. Nature 468, 545 (2010).

Keywords: Optical cavities; Bose-Einstein condensates; Open quantum systems; Lindblad formalism; Schwinger-Keldysh field theory