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

Ying-Tao Zhang,Xinzhou Deng,Zhenhua Qiao,Qing-Feng Sun

doi:10.1038/srep14892

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.

Highlights

The quantum entanglement between two qubits is crucial for applications in the quantum communication
Inspired by the exotic chirally propagating transport properties of the quantum anomalous Hall insulator (QAHI), we propose a Cooper-pair splitter in the hybrid system by coupling the QAHI with a superconductor
QAHI is a special realization of the quantum Hall effect[29,30] that occurs in the absence of an external magnetic field, in which the chiral edge states protected by the spatial-separation allow the dissipationless current transport in 2D electronic systems

Summary

Introduction

The quantum entanglement between two qubits is crucial for applications in the quantum communication. By making use of the crossed Andreev reflection, a Cooper-pair in the superconductor can be split into two electrons, which propagate at two spatially-separated terminals while keeping their spin and momentum entangled.

Results

Conclusion