Experimental quantum conference key agreement

Massimiliano Proietti, Joseph Ho, Federico Grasselli, Peter Barrow, Mehul Malik, Alessandro Fedrizzi

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)
46 Downloads (Pure)


Quantum networks will provide multinode entanglement enabling secure communication on a global scale. Traditional quantum communication protocols consume pair-wise entanglement, which is suboptimal for distributed tasks involving more than two users. Here, we demonstrate quantum conference key agreement, a cryptography protocol leveraging multipartite entanglement to efficiently create identical keys between N users with up to N-1 rate advantage in constrained networks. We distribute four-photon Greenberger-Horne-Zeilinger (GHZ) states, generated by high-brightness telecom photon-pair sources, over optical fiber with combined lengths of up to 50 km and then perform multiuser error correction and privacy amplification. Under finite-key analysis, we establish 1.5 × 106 bits of secure key, which are used to encrypt and securely share an image between four users in a conference transmission. Our work highlights a previously unexplored protocol tailored for multinode networks leveraging low-noise, long-distance transmission of GHZ states that will pave the way for future multiparty quantum information processing applications.

Original languageEnglish
Article numbereabe0395
JournalScience Advances
Issue number23
Publication statusPublished - 2 Jun 2021

ASJC Scopus subject areas

  • General


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