Entangling three identical particles via spatial overlap

TL;DR

This paper demonstrates the generation of genuine tripartite entanglement, specifically GHZ and W classes, among three identical photons, highlighting the role of particle indistinguishability in entanglement.

Contribution

It proposes and experimentally demonstrates schemes to create tripartite entanglement with three identical photons, extending understanding beyond two-particle systems.

Findings

Tripartite entanglement decays as particles become distinguishable.

Genuine entanglement can be generated with three identical photons.

Particle indistinguishability is essential for entangling identical particles.

Abstract

Quantum correlations between identical particles are at the heart of quantum technologies. Several studies with two identical particles have shown that the spatial overlap and indistinguishability between the particles are necessary for generating bipartite entanglement. On the other hand, researches on the extension to more than two-particle systems are limited by the practical difficulty to control multiple identical particles in laboratories. In this work, we propose schemes to generate two fundamental classes of genuine tripartite entanglement, i.e., GHZ and W classes, which are experimentally demonstrated with three identical photons. We also show that the tripartite entanglement class decays from the genuine entanglement to the full separability as the particles become more distinguishable from each other. Our results support the prediction that particle indistinguishability is a fundamental element for entangling identical particles.