Nonequilibrium transport through the Hubbard dimer

TL;DR

This paper introduces an efficient computational method using nonequilibrium Green's functions and the iGKBA to analyze spectral properties and transient currents in a two-site Hubbard model, revealing correlation effects.

Contribution

The paper develops a time-linear approach with iGKBA for studying nonequilibrium spectral properties in the Hubbard dimer, reducing computational costs compared to traditional methods.

Findings

Correlation-induced spectral shifts and broadenings

Suppression of transient current oscillations

Validation of the iGKBA approach for open quantum systems

Abstract

We apply a computationally efficient approach to study the time- and energy-resolved spectral properties of a two-site Hubbard model using the nonequilibrium Green's function formalism. By employing the iterative generalized Kadanoff-Baym ansatz ($i$GKBA) within a time-linear framework, we avoid the computational cost of solving the full two-time Kadanoff-Baym equations. Spectral information is extracted by coupling the system to multiple narrow-band leads, establishing a direct analogy to photoemission experiments. Our results reveal correlation-induced shifts and broadenings of spectral features, along with a suppression of transient current oscillations. This approach provides a promising avenue for analyzing correlated electron dynamics in open quantum systems.