Experimental Verification of Multipartite Entanglement in Quantum Networks

TL;DR

This paper presents an experimental protocol enabling parties in a quantum network to verify genuine multipartite entanglement securely, even with untrusted parties and system imperfections, demonstrated with photonic entangled photons.

Contribution

It introduces a novel verification protocol for multipartite entanglement that is secure against dishonest parties and verified experimentally in photonic systems.

Findings

Successfully verified multipartite entanglement in three- and four-party photonic systems.

Protocol remains secure against dishonest behavior and system imperfections.

Demonstrates practical applicability for quantum communication networks.

Abstract

Multipartite entangled states are a fundamental resource for a wide range of quantum information processing tasks. In particular, in quantum networks it is essential for the parties involved to be able to verify if entanglement is present before they carry out a given distributed task. Here we design and experimentally demonstrate a protocol that allows any party in a network to check if a source is distributing a genuinely multipartite entangled state, even in the presence of untrusted parties. The protocol remains secure against dishonest behaviour of the source and other parties, including the use of system imperfections to their advantage. We demonstrate the verification protocol in a three- and four-party setting using polarization-entangled photons, highlighting its potential for realistic photonic quantum communication and networking applications.