Detection of Nonlocal Spin Entanglement by Light Emission from a Superconducting p-n Junction

TL;DR

This paper proposes a method to detect nonlocal spin entanglement in a superconducting p-n junction by observing polarization-entangled photons emitted during Cooper pair transfer, using Bell tests to confirm entanglement.

Contribution

It introduces a model linking superconducting p-n junctions with optical quantum dots to generate and detect spin-entangled photons via Bell measurements.

Findings

Bell tests confirm entanglement over broad parameters

Entanglement persists despite parasitic processes

Photon polarization correlates with Cooper pair spin states

Abstract

We model a superconducting p-n junction in which the n- and the p-sides are contacted through two optical quantum dots (QDs), each embedded into a photonic nanocavity. Whenever a Cooper pair is transferred from the n-side to the p-side, two photons are emitted. When the two electrons of a Cooper pair are transported through different QDs, polarization-entangled photons are created, provided that the Cooper pairs retain their spin singlet character while being spatially separated on the two QDs. We show that a CHSH Bell-type measurement is able to detect the entanglement of the photons over a broad range of microscopic parameters, even in the presence of parasitic processes and imperfections.