Transport properties of proximitized double quantum dots

TL;DR

This paper investigates the sub-gap spectrum and transport phenomena in a double quantum dot system coupled to metallic and superconducting leads, highlighting non-local pairing, Cooper pair tunneling channels, and interference effects.

Contribution

It introduces a detailed analysis of Andreev reflection, non-local pairing, and interference effects in double quantum dots coupled to superconductors, revealing new transport mechanisms.

Findings

Identification of non-local pairing induced by superconducting coupling.

Discovery of two channels for Cooper pair tunneling.

Observation of Fano-type interference in conductance spectra.

Abstract

We study the sub-gap spectrum and the transport properties of a double quantum dot coupled to metallic and superconducting leads. The coupling of both quantum dots to the superconducting lead induces a non-local pairing in both quantum dots by the Andreev reflection processes. Additionally, we obtain two channels of Cooper pair tunneling into a superconducting lead. In such a system, the direct tunneling process (by one of two dots) or the crossed tunneling process (by both quantum dots at the same time) is possible. We consider the dependence of the Andreev transmittance on an inter-dot tunneling amplitude and the coupling between a quantum dot and the superconducting lead. We also consider the occurrence of interferometric Fano-type line shapes in the linear Andreev conductance spectra.