Nonequilibrium Steady State of Photoexcited Correlated Electrons in the Presence of Dissipation

TL;DR

This paper develops a framework to analyze nonequilibrium steady states in strongly correlated electron systems with dissipation, revealing novel optical phenomena under intense photoexcitation.

Contribution

It introduces an exact solution method combining Floquet theory and dynamical mean-field theory for correlated electrons with dissipation under strong photoirradiation.

Findings

Observation of photometallization with a Drude-like peak.

Prediction of dip and kink structures in optical conductivity.

Identification of midgap absorption and gain due to population inversion.

Abstract

We present a framework to determine nonequilibrium steady states in strongly correlated electron systems in the presence of dissipation. This is demonstrated for a correlated electron (Falicov-Kimball) model attached to a heat bath and irradiated by an intense pump light, for which an exact solution is obtained with the Floquet method combined with the nonequilibrium dynamical mean-field theory. On top of a Drude-like peak indicative of photometallization as observed in recent pump-probe experiments, new nonequilibrium phenomena are predicted to emerge, where the optical conductivity exhibits dip and kink structures around the frequency of the pump light, a midgap absorption arising from photoinduced Floquet subbands, and a negative attenuation (gain) due to a population inversion.