Entanglement swapping between spacelike separated atoms

TL;DR

This paper demonstrates a method to entangle two spacelike separated atoms through a measurement process involving the electromagnetic vacuum, enabling maximal entanglement even at large distances.

Contribution

It introduces a mechanism for entangling distant atoms via a partial Bell-state measurement, allowing entanglement across spacelike separations.

Findings

Maximal entanglement achieved between spacelike separated atoms.

Entanglement can be generated at arbitrary large distances.

Short interaction times and specific Bell-state detection are crucial.

Abstract

We show a mechanism that projects a pair of neutral two-level atoms from an initially uncorrelated state to a maximally entangled state while they remain spacelike separated. The atoms begin both excited in a common electromagnetic vacuum, and the radiation is collected with a partial Bell-state analyzer. If the interaction time is short enough and a certain two-photon Bell state is detected after the interaction, a high degree of entanglement, even maximal, can be generated while one atom is outside the light cone of the other, for arbitrary large interatomic distances.