Imaginary-time formulation of steady-state nonequilibrium in quantum dot models

TL;DR

This paper evaluates an imaginary-time approach for steady-state nonequilibrium in quantum dot models, improving analytic continuation methods and confirming key physical phenomena like Kondo resonance suppression at finite bias.

Contribution

It introduces enhanced analytic continuation techniques and detailed spectral representations, advancing the theoretical framework for nonequilibrium quantum transport.

Findings

Accurate differential conductance matches existing data.

Kondo resonance is suppressed at bias near the Kondo temperature.

Scaling coefficients align with experimental estimates.

Abstract

We examine the recently proposed imaginary-time formulation for strongly correlated steady-state nonequilibrium for its range of validity and discuss significant improvements in the analytic continuation of the Matsubara voltage as well as the fermionic Matsubara frequency. The discretization error in the conventional Hirsch-Fye algorithm has been compensated in the Fourier transformation with reliable small frequency behavior of self-energy. Here we give detailed discussions for generalized spectral representation ansatz by including high order vertex corrections and its numerical analytic continuation procedures. The differential conductance calculations agree accurately with existing data from other nonequilibrium transport theories. It is verified that, at finite source-drain voltage, the Kondo resonance is destroyed at bias comparable to the Kondo temperature. Calculated coefficients in the scaling relation of the zero bias anomaly fall within the range of experimental estimates.