Adiabatic pumping in a double-dot Cooper-pair beam splitter

TL;DR

This paper investigates adiabatic pumping in a double quantum dot system connected to normal and superconducting leads, focusing on distinguishing Cooper pair splitting from single-electron transport through theoretical analysis.

Contribution

It introduces a perturbation approach to analyze adiabatic pumping and identifies key features differentiating Cooper pair splitting from single-electron processes.

Findings

Crossed Andreev reflection influences pumped charge

Dependence on dot level and coupling asymmetry distinguishes transport types

Cooper pair pumping differs from single-electron pumping in key properties

Abstract

We study adiabatic pumping through a double quantum dot coupled to normal and superconducting leads. For this purpose a perturbation expansion in the tunnel coupling between the dots and the normal leads is performed and processes underlying the pumping current are discussed. Features of crossed Andreev reflection are investigated in the average pumped charge and related to local Andreev reflection in a single quantum dot. In order to distinguish Cooper pair splitting from quasi-particle pumping, we compare the properties of Cooper pair pumping with single-electron pumping in a system with only normal leads. The dependence on the average dot level and the coupling asymmetry turn out to be the main distinguishing features. This is contrasted with the linear conductance for which it is more difficult to distinguish single-particle from Cooper pair transport.