Density matrix renormalization group study of the charging of a quantum dot strongly coupled to a single lead

TL;DR

This paper applies the density matrix renormalization group (DMRG) method to study how a quantum dot's charge state is affected by strong coupling to a lead, revealing robustness of discrete states and Coulomb blockade effects.

Contribution

It introduces a novel application of DMRG to analyze the thermodynamics of an interacting quantum dot strongly coupled to a lead.

Findings

Discrete states persist in the dot under strong coupling.

Discrete states are robust against interactions.

Coulomb blockade influences dot charging despite strong lead coupling.

Abstract

A new application of the density matrix renormalization group (DMRG) method to a system composed of an interacting dot coupled to a infinite one dimensional lead is presented. This method enables one to study the influence of the coupling to an external lead on the thermodynamical properties of the dot. It is shown that this method reproduces known results for a non-interacting dot coupled to a lead, i.e., that for strong coupling discrete states remain in the dot. We show that these states are robust and do not disappear once interactions in the dot are considered. Moreover, due to these discrete states, Coulomb blockade affects the charging of the dot even though its strongly coupled to a lead.