Cooper Pair Splitting by means of Graphene Quantum Dots

TL;DR

This paper demonstrates Cooper pair splitting in a superconductor-graphene double quantum dot system, achieving up to 10% efficiency and distinguishing CPS from elastic co-tunneling through conductance correlations and energy level tuning.

Contribution

It presents the first experimental observation of Cooper pair splitting in a graphene quantum dot system with tunable energy levels.

Findings

CPS efficiency up to ~10% observed.

Positive conductance correlation detected across decoupled QDs.

Distinction between CPS and elastic co-tunneling achieved by energy level tuning.

Abstract

Split Cooper pair is a natural source for entangled electrons which is a basic ingredient for quantum information in solid state. We report an experiment on a superconductor-graphene double quantum dot (QD) system, in which we observe Cooper pair splitting (CPS) up to a CPS efficiency of ~ 10%. With bias on both QDs, we are able to detect a positive conductance correlation across the two distinctly decoupled QDs. Furthermore, with bias only on one QD, CPS and elastic co-tunneling can be distinguished by tuning the energy levels of the QDs to be asymmetric or symmetric with respect to the Fermi level in the superconductor.