Hannover 2013 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 45: Quantum gases: Bosons II
Q 45.5: Vortrag
Donnerstag, 21. März 2013, 12:00–12:15, F 342
Non-thermal fixed points in a two-component Bose gas across the miscible–immiscible transition — •Markus Karl1,2, Boris Nowak1,2, and Thomas Gasenzer1,2 — 1Institut für Theoretische Physik, Ruprecht-Karls-Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg — 2ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt, Germany
We present a numerical analysis of non-thermal fixed points in an ultracold two-component Bose gas in two spatial dimensions across the miscible–immiscible transition. Unstable initial conditions are used to drive the system away from equilibrium, aiming for the excitation of topological defects such as domain structures and vortices, and their influence on the intermediate and late time evolution of the system is studied. Thereby a special focus is set on transient turbulent states, which are signaled by the emergence of quasi-stationary scaling laws in the occupation spectrum, n(k) ∼ k−ζ. We find such quasi-stationary states far from equilibrium, so-called non-thermal fixed points, in all parameter regimes, i.e. in the miscible and the immiscible regime as well as at the transition point, accompanied by steady scaling laws with different scaling exponents, ζ, for the momentum distributions, which we are able to identify with the natural defect structures in the respective regimes.