Hierarchical equations of motion approach to transport through an Anderson impurity coupled to interacting Luttinger liquid leads

TL;DR

This paper extends the hierarchical equations of motion method to analyze electron transport through quantum dots coupled to interacting Luttinger liquid leads, revealing the significance of many-body correlations and power-law singularities.

Contribution

The work introduces a generalized hierarchical equations of motion approach for Luttinger liquid leads, enabling detailed study of many-body effects in quantum transport beyond noninteracting models.

Findings

Cotunneling effects are enhanced with attractive interactions or excitonic coupling.

Negative differential conductance near Coulomb blockade is slightly suppressed.

Two-particle correlations are minor at high temperatures and specific parameters.

Abstract

We generalize the hierarchical equations of motion method to study electron transport through a quantum dot or molecule coupled to one-dimensional interacting leads that can be described as Luttinger liquids. Such leads can be realized, for example, by quantum wires or fractional quantum Hall edge states. In comparison to noninteracting metallic leads, Luttinger liquid leads involve many-body correlations and the single-particle tunneling density of states shows a power-law singularity at the chemical potential. Using the generalized hierarchical equations of motion method, we assess the importance of the singularity and the next-to-leading order many-body correlations. To this end, we compare numerically converged results with second and first-order results of the hybridization expansion that is inherent to our method. As a test case, we study transport through a single-level quantum dot or molecule that can be described by an Anderson impurity model. Cotunneling effects turn out to be most pronounced for attractive interactions in the leads or repulsive ones if an excitonic coupling between the dot and the leads is realized. We also find that an interaction-induced negative differential conductance near the Coulomb blockade thresholds is slightly suppressed as compared to a first-order and/or rate equation result. Moreover, we find that the two-particle ($n$-particle) correlations enter as a second-order ($n$-order) effect and are, thus, not very pronounced at the high temperatures and parameters that we consider.