Entanglement-symmetry control in a quantum-dot Cooper-pair splitter

TL;DR

This paper explores how to control the symmetry of entangled electron pairs in a quantum-dot Cooper-pair splitter using spin-orbit coupling, enabling spatial entanglement without nonlocal superconducting coupling.

Contribution

It introduces a mechanism to control entanglement symmetry in a quantum-dot system via spin-orbit coupling, even without nonlocal superconducting interactions.

Findings

Interdot tunnelling enables spatial entanglement without nonlocal coupling.

Spin-orbit coupling allows control over entanglement symmetry (singlet/triplet).

Spin-orbit coupling does not reduce entanglement purity.

Abstract

The control of nonlocal entanglement in solid state systems is a crucial ingredient of quantum technologies. We investigate a Cooper-pair splitter based on a double quantum dot realised in a semiconducting nanowire. In the presence of interdot tunnelling the system provides a simple mechanism to develop spatial entanglement even in absence of nonlocal coupling with the superconducting lead. We discuss the possibility to control the symmetry (singlet or triplet) of spatially separated, entangled electron pairs taking advantage of the spin-orbit coupling of the nanowire. We also demonstrate that the spin-orbit coupling does not impact over the entanglement purity of the nonlocal state generated in the double quantum dot system.