High-Efficiency Cooper-Pair Splitter in Quantum Anomalous Hall Insulator Proximity-Coupled with Superconductor

TL;DR

This paper proposes a high-efficiency, disorder-robust Cooper-pair splitter using a quantum anomalous Hall insulator coupled with a superconductor, enabling entangled electron pairs with minimal backscattering.

Contribution

It introduces a novel device leveraging chiral edge states for efficient, disorder-resistant Cooper-pair splitting in solid-state quantum systems.

Findings

High-efficiency Cooper-pair splitting achieved.

Device remains functional despite disorder and system size exceeding coherence length.

Chiral edge states suppress local Andreev reflection, enhancing crossed Andreev reflection.

Abstract

The quantum entanglement between two qubits is crucial for applications in the quantum communication. After the entanglement of photons was experimentally realized, much effort has been taken to exploit the entangled electrons in solid-state systems. Here, we propose a Cooper-pair splitter, which can generate spatially-separated but entangled electrons, in a quantum anomalous Hall insulator proximity-coupled with a superconductor. After coupling with a superconductor, the chiral edge states of the quantum anomalous Hall insulator can still survive, making the backscattering impossible. Thus, the local Andreev reflection becomes vanishing, while the crossed Andreev reflection becomes dominant in the scattering process. This indicates that our device can serve as an extremely high-efficiency Cooper-pair splitter. Furthermore, because of the chiral characteristic, our Cooper-pair splitter is robust against disorders and can work in a wide range of system parameters. Particularly, it can still function even if the system length exceeds the superconducting coherence length.