Thomas Gasenzer (U. Heidelberg)
Universal dynamics near non-thermal fixed points

Quenched quantum systems can show universal dynamics near non-thermal fixed points, generically in the form of scaling behaviour in space and time [1-3]. Systems where such fixed points can be realized range from post-inflationary evolution of the early universe to low-energy dynamics in cold gases. Effective field theories hold promise to describe the non-perturbative infrared dynamics by allowing to identify the relevant degrees of freedom. The status of different examples and their relevance to near-linear quasiparticle dynamics as well as to the strongly non-linear dynamics of solitary waves and topological defects will be discussed.

[1] C.-M. Schmied, A. N. Mikheev, T. Gasenzer, Non-thermal fixed points: Universal dynamics far from equilibrium, Int. J. Mod. Phys. A 34, no. 29 (2019) arXiv:1810.08143 [cond-mat.quant-gas].

[2] M. Pruefer et al., Observation of universal dynamics in a spinor Bose gas far from equilibrium, Nature 563, 217 (2018).

[3] S. Erne et al., Universal dynamics in an isolated one-dimensional Bose gas far from equilibrium, Nature 563, 225 (2018).