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DY: Fachverband Dynamik und Statistische Physik

DY 29: Many-body Quantum Dynamics

DY 29.7: Vortrag

Mittwoch, 3. April 2019, 11:15–11:30, H19

Observation of universal dynamics in a spinor Bose gas far from equilibrium — •Maximilian Prüfer¹, Philipp Kunkel¹, Helmut Strobel¹, Stefan Lannig¹, Daniel Linnemann¹, Christian-Marcel Schmied¹, Jürgen Berges², Thomas Gasenzer¹, and Markus K. Oberthaler¹ — ¹Kirchhoff-Institut für Physik, Universität Heidelberg — ²Institut für Theoretische Physik, Universität Heidelberg

Far from equilibrium different scenarios on the way to equilibrium have been identified. Here, we present a new scenario featuring universal dynamics associated to the existence of non-thermal fixed points [1]. We access and study this regime experimentally for a Bose-Einstein condensate of ⁸⁷Rb in the F = 1 hyperfine manifold with ferromagnetic interactions. We quench an experimental control parameter, which leads to a build-up of excitations in the transversal spin. We identify a regime in the time evolution where the in-plane orientation of this spin becomes the relevant dynamical degree of freedom. Spatially resolved read-out allows the momentum resolved study of correlation functions which show rescaling in time and space - the dynamics is solely captured by a universal scaling function and associated exponents. We experimentally identify an emergent conserved quantity which is transported towards low momentum scales. By preparing different initial conditions we confirm that the non-thermal scaling involves no fine tuning of parameters.

[1] Prüfer, M. et al., Nature 563, 217-220 (2018)