Comparative study of theoretical methods for nonequilibrium quantum transport

TL;DR

This paper compares three advanced theoretical methods—fRG, tDMRG, and ISPI—for analyzing nonequilibrium quantum transport in the single-impurity Anderson model, demonstrating their quantitative agreement across various parameters.

Contribution

It provides a comprehensive comparison of three different theoretical approaches for nonequilibrium quantum transport, highlighting their agreement and applicability.

Findings

The three methods agree quantitatively over a wide parameter range.

Comparison with quantum Monte Carlo and NRG methods validates their accuracy.

The methods are effective at the particle-hole symmetric point and in the mixed-valence regime.

Abstract

We present a detailed comparison of three different methods designed to tackle nonequilibrium quantum transport, namely the functional renormalization group (fRG), the time-dependent density matrix renormalization group (tDMRG), and the iterative summation of real-time path integrals (ISPI). For the nonequilibrium single-impurity Anderson model (including a Zeeman term at the impurity site), we demonstrate that the three methods are in quantitative agreement over a wide range of parameters at the particle-hole symmetric point as well as in the mixed-valence regime. We further compare these techniques with two quantum Monte Carlo approaches and the time-dependent numerical renormalization group method.