Quantum quenches, dynamical transitions and off-equilibrium quantum criticality

TL;DR

This paper investigates the critical properties of out-of-equilibrium dynamical transitions in quantum phi^4 field theory, revealing diverging scales, dynamic scaling, aging, and connections to coarsening beyond mean-field approximations.

Contribution

It extends the understanding of quantum dynamical transitions by incorporating fluctuations beyond mean-field theory in the phi^4 model, including finite temperature effects.

Findings

Diverging time and length scales at the transition

Observation of dynamic scaling and aging phenomena

Identification of a relationship with coarsening dynamics

Abstract

Several mean-field computations have revealed the existence of an out of equilibrium dynamical transition induced by quantum quenching an isolated system starting from its symmetry broken phase. In this work we focus on the quantum phi^4 N-component field theory. By taking into account dynamical fluctuations at the Hartree-Fock level, corresponding to the leading order of the 1/N expansion, we derive the critical properties of the dynamical transition beyond mean-field theory (including at finite temperature). We find diverging time and length-scales, dynamic scaling and aging. Finally, we unveil a relationship with coarsening, an off-equilibrium dynamical regime that can be induced by quenching from the symmetric toward the symmetry broken phase.