SP Seminar @SISSA Via Bonomea 265 Tuesday 14 May - T. GASENZER

[CM Section]

Joint ICTP/SISSA Statistical Physics Seminar

Tuesday 14 May at 11:00 a.m.
venue SISSA, Via Bonomea 265

Speaker:
T. GASENZER (Heidelberg University, Germany)

Title:
Universal Dynamics near Non-Thermal Fixed Points
and Quantum Turbulence

Abstract:

Quenched or continuously driven quantum systems can show universal
dynamics near non-thermal fixed points, generically in the form of scaling
behaviour in space and time. Key aspects of the theory of non-thermal fixed
points will be briefly summarized [1,2], as well as recent experimental 
results
for quenched systems [3,4]. In a dilute Bose gas, universal scaling dynamics
can be due to both, linear and non-linear excitations of the system. 
Considering
scaling transport of excitations to larger wave numbers similar to an 
inverse
cascade, the underlying excitations can be either irregular phase 
excitations
or (quasi) topological defects exhibiting the implications for quantum 
turbulence.
As an example, strongly anomalous scaling of inverse transport in a 
two-dimensional
superfluid due to higher-order vortex annihilation will be discussed 
both, from the
theoretical [5] and experimental point of view.

References:
[1] C.-M. Schmied, A. N. Mikheev, T. Gasenzer, Non-thermal fixed points: 
Universal
dynamics far from equilibrium, arXiv:1810.08143 [cond-mat.quant-gas]
[2] A. N. Mikheev, C.-M. Schmied, T. Gasenzer, Low-energy effective 
theory of non-
thermal fixed points in a multicomponent Bose gas, arXiv:1807.10228 
[cond-mat.quant-gas]
[3] M. Prüfer, P. Kunkel, H. Strobel, S. Lannig, D. Linnemann, C.-M. 
Schmied, J. Berges,
T. Gasenzer, M.K. Oberthaler, Observation of universal dynamics in a 
spinor Bose gas far
from equilibrium, Nature 563, 217 (2018).
[4] S. Erne, R. Bücker, T. Gasenzer, J. Berges and J. Schmiedmayer, 
Universal dynamics
in an isolated one-dimensional Bose gas far from equilibrium, Nature 
563, 225 (2018).
[5] M. Karl and T. Gasenzer, Strongly anomalous non-thermal fixed point 
in a quenched
two-dimensional Bose gas, New J. Phys. 19, 093014 (2017).