Nonequilibrium dynamical mean-field theory for bosonic lattice models

TL;DR

This paper extends bosonic dynamical mean-field theory to nonequilibrium situations, enabling the study of dynamical transitions, damping, and thermalization in bosonic lattice models after quenches.

Contribution

It introduces a nonequilibrium BDMFT framework with a strong-coupling impurity solver, capturing complex dynamical phenomena beyond previous mean-field and perturbative methods.

Findings

Different dynamical regimes identified in Bose-Hubbard model quenches

Observation of thermalization, metastable states, and damping effects

Non-equilibrium phase diagrams mapping dynamical behaviors

Abstract

We develop the nonequilibrium extension of bosonic dynamical mean field theory (BDMFT) and a Nambu real-time strong-coupling perturbative impurity solver. In contrast to Gutzwiller mean-field theory and strong coupling perturbative approaches, nonequilibrium BDMFT captures not only dynamical transitions, but also damping and thermalization effects at finite temperature. We apply the formalism to quenches in the Bose-Hubbard model, starting both from the normal and Bose-condensed phases. Depending on the parameter regime, one observes qualitatively different dynamical properties, such as rapid thermalization, trapping in metastable superfluid or normal states, as well as long-lived or strongly damped amplitude oscillations. We summarize our results in non-equilibrium "phase diagrams" which map out the different dynamical regimes.