High Efficiency CVD Graphene-lead (Pb) Cooper Pair Splitter

TL;DR

This paper reports a graphene-based Cooper pair splitter with high efficiency and visibility, utilizing a novel Y-shape design and CVD-grown graphene to improve quantum dot performance and device scalability.

Contribution

The study introduces a graphene-based device with a Y-shape design for enhanced Cooper pair splitting efficiency, using CVD-grown graphene for scalable fabrication.

Findings

Splitting efficiency up to 62%

Visibility of up to 96%

Large superconducting gap of 0.5 meV

Abstract

We demonstrate high efficiency Cooper pair splitting in a graphene-based device. We utilize a true Y-shape design effectively placing the splitting channels closer together: graphene is used as the central superconducting electrode as well as QD output channels, unlike previous designs where a conventional superconductor was used with tunnel barriers to the quantum dots (QD) of a different material. Superconductivity in graphene is induced via the proximity effect, thus resulting in both a large measured superconducting gap $\Delta=0.5$meV, and a long coherence length $\xi=200$nm. The graphene-graphene, flat, two dimensional, superconductor-QD interface lowers the capacitance of the quantum dots, thus increasing the charging energy $E_C$ (in contrast to previous devices). As a result we measure a visibility of up to 96% and a splitting efficiency of up to 62%. Finally, the devices utilize graphene grown by chemical vapor deposition allowing for a standardized device design with potential for increased complexity.