Unexpected Conductance Dip in the Kondo Regime of Linear Arrays of Quantum Dots

TL;DR

This paper investigates an unusual conductance dip in linear quantum dot arrays within the Kondo regime, revealing a conductance vanishing at specific gate voltages due to interference effects, confirmed through exact-diagonalization and embedding techniques.

Contribution

It uncovers a novel conductance dip phenomenon in quantum dot arrays caused by interference effects, expanding understanding of Kondo physics in such systems.

Findings

Conductance vanishes at specific gate voltages due to interference.

The conductance dip persists even when particle-hole symmetry is broken.

Hubbard interaction and electron statistics are key to understanding the effect.

Abstract

Using exact-diagonalization of small clusters and Dyson equation embedding techniques, the conductance $G$ of linear arrays of quantum dots is investigated. The Hubbard interaction induces Kondo peaks at low temperatures for an odd number of dots. Remarkably, the Kondo peak is split in half by a deep minimum, and the conductance vanishes at one value of the gate voltage. Tentative explanations for this unusual effect are proposed, including an interference process between two channels contributing to $G$, with one more and one less particle than the exactly-solved cluster ground-state. The Hubbard interaction and fermionic statistics of electrons also appear to be important to understand this phenomenon. Although most of the calculations used a particle-hole symmetric Hamiltonian and formalism, results also presented here show that the conductance dip exists even when this symmetry is broken. The conductance cancellation effect obtained using numerical techniques is potentially interesting, and other many-body techniques should be used to confirm its existence.