Erlangen 2018 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 38: Poster: Quantum Optics and Photonics I

Q 38.5: Poster

Dienstag, 6. März 2018, 16:15–18:15, Orangerie

Kinetic theory of non-thermal fixed points in a Bose gas — •Aleksandr Mikheev, Christian-Marcel Schmied, Isara Chantesana, and Thomas Gasenzer — Kirchhoff-Institut für Physik, INF 227, 69120 Heidelberg, Germany

We outline a kinetic theory of non-thermal fixed points for the example of a dilute Bose gas. We study universal dynamics after a cooling quench, focusing on situations where the time evolution represents a pure rescaling of spatial correlations, with time defining the scale parameter. Possible universal dynamics is identified by means of a scaling analysis of the kinetic equation describing the interactions of (quasi)particle field modes. The non-equilibrium initial condition set by the quench induces a redistribution of particles in momentum space. This can take the form of a wave-turbulent flux or more general evolution in which the momentum distribution shifts in a self-similar manner, signaling the critically slowed approach of a non-thermal fixed point. The approach of the fixed point is tied to collective scattering between highly occupied long-wavelength modes which require a description in terms of a non-perturbative kinetic theory. We obtain a possible finite-size interpretation of wave-turbulent scaling recently measured by Navon et al. [N. Navon, A. L. Gaunt, R. P. Smith, and Z. Hadzibabic, Nature 539, 72 (2016)].