A pseudo-fermion method for the exact description of fermionic environments: from single-molecule electronics to Kondo resonance

TL;DR

This paper introduces a pseudo-fermion method to accurately model fermionic environments in quantum systems, effectively capturing complex phenomena like Kondo resonance without approximations.

Contribution

The authors develop a pseudo-fermion decomposition approach that allows exact modeling of fermionic baths, including strong correlations, using imaginary parameters and damping.

Findings

Accurately reproduces analytical solutions for non-interacting systems.

Captures low-temperature Kondo physics in interacting systems.

Demonstrates effectiveness against hierarchical-equations-of-motion benchmarks.

Abstract

We develop a discrete fermion approach for modelling the strong interaction of an arbitrary system interacting with continuum electronic reservoirs. The approach is based on a pseudo-fermion decomposition of the continuum bath correlation functions, and is only limited by the accuracy of this decomposition. We show that to obtain this decomposition one can allow for imaginary pseudo-fermion parameters, and strong damping in individual pseudo-fermions, without introducing unwanted approximations. For a non-interacting single-resonant level, we benchmark our approach against an analytical solution and an exact hierachical-equations-of-motion approach. We also show that, for the interacting case, this simple method can capture the strongly correlated low-temperature physics of Kondo resonance.