Heralded Entanglement of Arbitrary Degree in Remote Qubits

TL;DR

This paper demonstrates a method to generate and control entanglement of arbitrary degree between remote qubits using photon scattering, with tunable entanglement levels and an analog to Malus' law, relevant for quantum communication.

Contribution

It introduces a novel approach to herald and tune entanglement degrees in remote qubits via photon scattering and interferometry, expanding control over quantum entanglement.

Findings

Entanglement degree is tunable by experimental parameters.

An analog to Malus' law is observed in the system.

Estimated impact of experimental uncertainties on entanglement variation.

Abstract

Incoherent scattering of photons off two remote atoms with a Lambda-level structure is used as a basic Young-type interferometer to herald long-lived entanglement of an arbitrary degree. The degree of entanglement, as measured by the concurrence, is found to be tunable by two easily accessible experimental parameters. Fixing one of them to certain values unveils an analog to the Malus' law. An estimate of the variation in the degree of entanglement due to uncertainties in an experimental realization is given.