EurekAlert June 6, 2021
Traditional quantum communication protocols consume pair-wise entanglement, which is suboptimal for distributed tasks involving more than two users. An international team of researchers (UK, Germany) has demonstrated quantum conference key agreement leveraging multipartite entanglement to efficiently create identical keys between N users with up to N-1 rate advantage in constrained networks. They distributed 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 performed multiuser error correction and privacy amplification. Under finite-key analysis, they established 1.5 × 106 bits of secure key, which were used to encrypt and securely share an image between four users in a conference transmission. Their 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…read more. Open Access TECHNICAL ARTICLEÂ
Quantum conference key agreement scheme and experimental layout. Credit: Science Advances 04 Jun 2021, Vol. 7, no. 23, eabe0395Â