Creation and detection of mobile and non-local spin-entangled electrons

TL;DR

This paper reviews devices that generate and detect mobile spin-entangled electrons, focusing on mechanisms to produce spatially separated entanglement and methods for its measurement via charge noise correlations.

Contribution

It introduces various setups for creating and detecting spin-entangled electrons, emphasizing the use of quantum dots and Coulomb blockade effects for spatial separation and Bell-type measurements.

Findings

Suppression of same-lead tunneling via Coulomb blockade enhances entanglement fidelity.

Quantum dots can be used to perform Bell tests with charge noise measurements.

Feasibility of detecting spin-entanglement through charge noise correlations is discussed.

Abstract

We present electron spin entanglers--devices creating mobile spin-entangled electrons that are spatially separated--where the spin-entanglement in a superconductor present in form of Cooper pairs and in a single quantum dot with a spin singlet groundstate is transported to two spatially separated leads by means of a correlated two-particle tunneling event. The unwanted process of both electrons tunneling into the same lead is suppressed by strong Coulomb blockade effects caused by quantum dots, Luttinger liquid effects or by resistive outgoing leads. In this review we give a transparent description of the different setups, including discussions of the feasibility of the subsequent detection of spin-entanglement via charge noise measurements. Finally, we show that quantum dots in the spin filter regime can be used to perform Bell-type measurements that only require the measurement of zero frequency charge noise correlators.