Entanglement distribution over a 96-km-long submarine optical fiber

Sören Wengerowsky*, Siddarth Koduru Joshi, Fabian Steinlechner, Julien R. Zichi, Sergiy M. Dobrovolskiy, René van der Molen, Johannes W.N. Los, Val Zwiller, Marijn A.M. Versteegh, Alberto Mura, Davide Calonico, Massimo Inguscio, Hannes Hübel, Liu Bo, Thomas Scheidl, Anton Zeilinger, André Xuereb, Rupert Ursin

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

45 Citations (Scopus)
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Quantum entanglement is one of the most extraordinary effects in quantum physics, with many applications in the emerging field of quantum information science. In particular, it provides the foundation for quantum key distribution (QKD), which promises a conceptual leap in information security. Entanglement-based QKD holds great promise for future applications owing to the possibility of device-independent security and the potential of establishing global-scale quantum repeater networks. While other approaches to QKD have already reached the level of maturity required for operation in absence of typical laboratory infrastructure, comparable field demonstrations of entanglement-based QKD have not been performed so far. Here, we report on the successful distribution of polarization-entangled photon pairs between Malta and Sicily over 96 km of submarine optical telecommunications fiber. We observe around 257 photon pairs per second, with a polarization visibility above 90%. Our results show that QKD based on polarization entanglement is now indeed viable in long-distance fiber links. This field demonstration marks the longest-distance distribution of entanglement in a deployed telecommunications network and demonstrates an international submarine quantum communication channel. This opens up myriad possibilities for future experiments and technological applications using existing infrastructure.

Original languageEnglish
Pages (from-to)6684-6688
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number14
Early online date14 Mar 2019
Publication statusPublished - 2 Apr 2019


  • Polarization-entangled photons
  • Quantum cryptography
  • Quantum entanglement
  • Quantum key distribution


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