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Q: Fachverband Quantenoptik und Photonik

Q 10: Quantum Gases (Bosons) I

Q 10.3: Vortrag

Montag, 5. März 2018, 11:00–11:15, K 2.020

Observation of universal dynamics in an isolated quantum system — •Maximilian Prüfer¹, Philipp Kunkel¹, Christian-Marcel Schmied¹, Daniel Linnemann¹, Stefan Lannig¹, Helmut Strobel¹, Jürgen Berges², Thomas Gasenzer¹, and Markus K. Oberthaler¹ — ¹Kirchhoff-Institut für Physik, Im Neuenheimer Feld 227, 69120 Heidelberg — ²Institut für Theoretische Physik, Philosophenweg 16, 69120 Heidelberg

After a quench a non-integrable many-particle system will eventually relax to its thermal state. However, on the route to thermalisation universal dynamics characterised by temporal rescaling of spatial correlation functions may be encountered, a phenomenon known as a non-thermal fixed point. We access and study this regime both experimentally and theoretically for a Bose-Einstein condensate of ⁸⁷Rb in the F = 1 hyperfine manifold with ferromagnetic interactions. We prepare our system in the polar phase and quench into the easy-plane ferromagnetic phase. After a build-up of excitations in the transversal spin we observe self-similar evolution, which is due to the non-linear redistribution of excitations among different momenta. We determine the emerging scaling form for the structure factor of the transversal spin and extract the set of corresponding scaling exponents. Our results give access to universal properties of the transient dynamics towards thermal equilibrium.