Regensburg 2019 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 34: Nonequilibrium Quantum Many-Body Systems 2

TT 34.1: Talk

Tuesday, April 2, 2019, 14:00–14:15, H22

Thermalization and Bose-Einstein condensation dynamics of photons coupled to a dye-molecule bath — •Michael Kajan and Johann Kroha — Physikalisches Institut, Universität Bonn, Germany

Discrete electronic or spin excitations in molecules or atoms coupled to vibrations are often described by the Jaynes-Cummings or the spin-boson models. When, in addition, the electronic excitations are coupled to the electromagnetic environment via photon emission and absorption, the system becomes not exactly solvable due to the non-canonical dynamics of the (pseudo)spins. Experimentally, by the emission of photons from a reservoir of laser-pumped dye molecules into an optical cavity with a non-zero lower band cutoff or with a discrete mode spectrum, thermalization and Bose-Einstein condensation of the photon gas has been realized [1]. We develop a novel slave boson representation for the molecule dynamics which accounts for all molecular states, electronic and vibrational, on the same footing. It makes the dynamics of photons coupled to the non-Markovian bath of molecule excitations tractable by standard diagrammatic techniques. We extend the method to describe Bose-Einstein condensation of the photons. It can be generalized in a straight-forward way to non-equilibrium time-dependent dynamics using the Keldysh technique.
J. Klaers, J. Schmitt, F. Vewinger, M. Weitz, Nature 468, 545 (2010)