High-rate measurement-device-independent quantum cryptography

Stefano Pirandola, Carlo Ottaviani, Gaetana Spedalieri, Christian Weedbrook, Samuel L. Braunstein, Seth Lloyd, Tobias Gehring, Christian Scheffmann Jacobsen, Ulrik Lund Andersen

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Quantum cryptography achieves a formidable task - the remote distribution of secret keys by exploiting the fundamental laws of physics. Quantum cryptography is now headed towards solving the practical problem of constructing scalable and secure quantum networks. A significant step in this direction has been the introduction of measurement-device independence, where the secret key between two parties is established by the measurement of an untrusted relay. Unfortunately, although qubit-implemented protocols can reach long distances, their key rates are typically very low, unsuitable for the demands of a metropolitan network. Here we show, theoretically and experimentally, that a solution can come from the use of continuous-variable systems. We design a coherent-state network protocol able to achieve remarkably high key rates at metropolitan distances, in fact three orders of magnitude higher than those currently achieved. Our protocol could be employed to build high-rate quantum networks where devices securely connect to nearby access points or proxy servers.
Original languageEnglish
JournalNature Photonics
Issue number6
Pages (from-to)397-402
Publication statusPublished - 2015


  • Access control
  • Cryptography
  • Mobile security
  • Network protocols
  • Network security
  • Continuous variable system
  • Fundamental laws
  • Measurement device
  • Metropolitan networks
  • Practical problems
  • Quantum network
  • Three orders of magnitude
  • Untrusted relays
  • Quantum cryptography

Cite this

Pirandola, S., Ottaviani, C., Spedalieri, G., Weedbrook, C., Braunstein, S. L., Lloyd, S., Gehring, T., Jacobsen, C. S., & Andersen, U. L. (2015). High-rate measurement-device-independent quantum cryptography. Nature Photonics, 9(6), 397-402. https://doi.org/10.1038/nphoton.2015.83