Stuttgart 2012 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 4: Quanteneffekte: QED
Q 4.8: Talk
Monday, March 12, 2012, 12:15–12:30, V7.01
Nonthermal fixed points, scaling of an ultracold bose gas — •Nikolai Philipp1,2 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
Turbulent scaling phenomena are studied in an ultracold Bose gas away from thermal equilibrium. Fixed points of the dynamical evolution are characterized in terms of universal scaling exponents of correlation functions. The scaling behavior is determined analytically in the framework of quantum field theory, using a nonperturbative approximation of the two-particle irreducible effective action as well functional flow equations for proper correlation functions. Anomalously large exponents arise in the infrared regime of the turbulence spectrum which recently were demonstrated to be related to the appearance of topological excitations of the superfluid. We compute the power-law exponents in the framework of the Wetterich functional renormalisation group equation and compare with previously obtained results.