Sum Rules and Asymptotic Behaviors for Optical Conductivity of Nonequilibrium Many-Electron Systems

TL;DR

This paper derives exact sum rules and asymptotic behaviors for the optical conductivity of nonequilibrium many-electron systems driven by external fields, providing theoretical tools for experimental analysis.

Contribution

It introduces universal sum rules and asymptotic behaviors for differential optical conductivity in nonequilibrium systems, expanding theoretical understanding.

Findings

Derived exact sum rules for differential optical conductivity.

Established asymptotic behaviors of response functions.

Uncovered universal properties of time-dependent nonequilibrium systems.

Abstract

For many-electron systems, we consider a nonequilibrium state (NES) that is driven by a pump field(s), which is either an optical field or a longitudinal electric field. For the differential optical conductivity describing the differential response of the NES to a probe optical field, we derive exact sum rules and asymptotic behaviors, which open wide possibilities for experiments. In deriving these results, we have also derived universal properties of general differential response functions of time-dependent NESs of general systems.