The dark side of benzene: interference vs. interaction

TL;DR

This paper investigates how electron interactions influence conductance in a quantum ring structure with interference effects, revealing Kondo resonances and population blocking phenomena through advanced computational methods.

Contribution

It introduces an extended Kubo approach combined with DMRG to analyze interaction and interference effects in a six-site ring with flux.

Findings

Observation of Kondo-like resonance at large hopping

Identification of additional resonance peaks due to population blocking

Demonstration of interaction effects on conductance in a flux-threaded ring

Abstract

We present the study of the linear conductance vs.\ applied gate voltage for an interacting six site ring structure, which is threaded by a flux of $\pi$ and coupled to a left and a right lead. This ring structure is designed to have a vanishing conductance for all gate voltages and temperatures provided interactions are ignored. Therefore this system is an ideal testbed to study the interplay of interaction and interference. First we find a Kondo type resonance for rather large hopping parameter. Second, we find additional resonance peaks which can be explained by a population blocking mechanism. To this end we have to extend the Kubo approach within the Density Matrix Renormalization Group method to handle degenerate states.