Hannover 2013 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 56: Poster III
Q 56.3: Poster
Donnerstag, 21. März 2013, 16:00–18:30, Empore Lichthof
Nonthermal Fixed Points and Superfluid Turbulence in an Ultracold Bose Gas — Sebastian Erne1,2, •Markus Karl1,2, Steven Mathey1,2, Boris Nowak1,2, Nikolai Philipp1,2, Jan Schole1,2, 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
Turbulence appears in situations in which, e.g., an energy flux goes from large to small scales where finally the energy is dissipated. As a result the distribution of occupation numbers of excitations follows a power law with a universal critical exponent. The situation can be described as a nonthermal fixed point of the dynamical equations. Single-particle momentum spectra for a dynamically evolving Bose gas are analysed using semi-classical simulations and quantum-field theoretic methods based on effective-action techniques. These give information about possible universal scaling behaviour. The connection of this scaling with the appearance of topological excitations such as solitons and vortices in one-component gases and domain walls and spin textures in multi-component systems is discussed. For the one-dimensional case, a random-soliton model provides analytical results for the spectra, and their relation to those found in a field-theory approach to strong wave turbulence is discussed. The results open a view on a possibility to study nonthermal fixed points and superfluid turbulence in experiment without the necessity of detecting solitons and vortices in situ.