Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 35: PhD Symposium: Quantum Phase Transitions: Emergent Phenomena beyond Elementary Excitations (organized by MA, jDPG)
TT 35.6: Talk
Tuesday, March 17, 2015, 12:45–13:00, EB 301
Universal Postquench Prethermalization at a Quantum Critical Point — •Pia Gagel1, Peter Orth1, and Jörg Schmalian1,2 — 1Institute for Theory of Condensed Matter, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany — 2Institute for Solid State Physics, Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany
We consider an open system near a quantum critical point that is suddenly moved towards the critical point. The bath-dominated diffusive nonequilibrium dynamics after the quench is shown to follow scaling behavior, governed by a critical exponent that emerges in addition to the known equilibrium critical exponents. We determine this exponent and show that it describes universal prethermalized coarsening dynamics of the order parameter in an intermediate time regime. Implications of this quantum critical prethermalization are: (i) a power law rise of order and correlations after an initial collapse of the equilibrium state and (ii) a crossover to thermalization that occurs arbitrarily late for sufficiently shallow quenches.