Soft Seminars

Finite-time dynamical phase transitions in non-equilibrium relaxation

by Dr Jan Meibohm (King's College London)

Room 4205 (Albano Building 3)

Room 4205

Albano Building 3


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Thermal relaxation is a fundamental process in statistical mechanics, with numerous applications in Nature and industry. Nonetheless, the kinetics of relaxation is well understood only close to equilibrium. Far-from-equilibrium relaxation, by contrast, is a genuine non-equilibrium problem that offers fascinating open questions and a variety of unexpected phenomena.

In my talk, I will discuss a particular class of such phenomenona, namely finite-time dynamical phase transitions. Such transitions occur at finite critical times during the transient relaxation of interacting many-body systems at the mean-field level after an instantaneous temperature quench. They manifest themselves as finite-time cusp singularities in the probability distributions of thermodynamic observables. The transitions are due to sudden switches in the relaxation dynamics and they are characterised by dynamical order parameters. I will introduce a dynamical Landau theory, that unambiguously determines the dynamical phases of the system and that allows to classify finite-time dynamical transitions in terms of equilibrium categories. Beyond the mean-field treatment critical, spatiotemporal fluctuations of the order parameter may give rise to novel, dynamical critical phenomena.