Numerical method to compute optical conductivity based on pump-probe simulations

TL;DR

This paper introduces a numerical approach for calculating optical conductivity using pump-probe simulations, validated on a Hubbard model in both equilibrium and nonequilibrium states, revealing probe-pulse dependence in ultrafast spectroscopy.

Contribution

The paper presents a novel numerical method for optical conductivity calculation based on pump-probe simulations, with analysis of probe-pulse effects in nonequilibrium conditions.

Findings

Method aligns with linear response theory in narrow-probe limit.

Probe-pulse dependence affects optical conductivity calculations.

Validates approach on Hubbard model in various states.

Abstract

A numerical method to calculate optical conductivity based on a pump-probe setup is presented. Its validity and limits are tested and demonstrated via the concrete numerical simulations on the half-filled one-dimensional extended Hubbard model both in equilibrium and out of equilibrium. By employing either a step- or a Gaussian-like probing vector potential, it is found that in nonequilibrium, the method in the narrow-probe-pulse limit can be identified with variant types of linear response theory, which, in equilibrium, produce identical results. The observation reveals the underlying probe-pulse dependence of the optical conductivity calculations in nonequilibrium, which may have its applications in the theoretical analysis of ultrafast spectroscopy measurements.