Nonlocal entanglement in hybrid superconducting and normal-metal three terminal devices

TL;DR

This paper demonstrates experimental control of nonlocal Andreev reflection in hybrid superconducting/normal-metal devices, providing evidence for spin-entanglement of electrons through resistance and current correlation measurements.

Contribution

It introduces a method to maximize nonlocal Andreev reflection by independently controlling electron energies at interfaces, advancing entanglement studies in electronic systems.

Findings

Evidence of nonlocal Andreev reflection through resistance measurements

Control of electron energy enhances spin-entanglement signatures

Observation of positive current-current correlations

Abstract

Nonlocal entanglement is crucial for quantum information processes. While nonlocal entanglement has been realized for photons, it is much more difficult to demonstrate for electrons. One approach that has been proposed is to use hybrid superconducting/normal-metal devices, where a Cooper pair splits into spin-entangled electrons in two spatially separated normal-metal leads. This process of nonlocal Andreev reflection is predicted to lead to a negative nonlocal resistance and positive current-current correlation. By cross-correlation measurements as well as measurements of the local and nonlocal resistance, we present here experimental evidence showing that by independently controlling the energy of electrons at the superconductor/normal-metal interfaces, nonlocal Andreev reflction, the signature of spin-entanglement, can be maximized.