Quasiclassical approach to quantum quench dynamics in the presence of an excited-state quantum phase transition

The dynamics of a quantum system following a sudden, highly nonadiabatic change of its control parameter (quantum quench) is studied with quasiclassical techniques. Recent works have shown, using exact quantum mechanical approach, that equilibration after quantum quench exhibits specific features in the presence of excited-state quantum phase transitions. In this paper, we demonstrate that these features can be understood from the classical evolution of the Wigner function in phase space.