Near-unity Cooper pair splitting efficiency

TL;DR

This paper demonstrates near-unity efficiency in Cooper pair splitting using quantum dots, achieving up to 90%, which is significant for testing electron entanglement and advancing quantum information technologies.

Contribution

The study reports a substantial increase in CPS efficiency to 90%, surpassing previous limitations and enabling practical tests of electron entanglement.

Findings

Achieved up to 90% CPS efficiency.

Compared CPS currents through quantum dots.

Explained discrepancies with a semi-classical model.

Abstract

The two electrons of a Cooper pair in a conventional superconductor form a singlet and therefore a maximally entangled state. Recently, it was demonstrated that the two particles can be extracted from the superconductor into two spatially separated contacts via two quantum dots (QDs) in a process called Cooper pair splitting (CPS). Competing transport processes, however, limit the efficiency of this process. Here we demonstrate efficiencies up to 90%, significantly larger than required to demonstrate interaction-dominated CPS, and on the right order to test Bell's inequality with electrons. We compare the CPS currents through both QDs, for which large apparent discrepancies are possible. The latter we explain intuitively and in a semi-classical master equation model. Large efficiencies are required to detect electron entanglement and for prospective electronics-based quantum information technologies.