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Experimental demonstration of long-distance continuous-variable quantum key distribution

Nature Photonics volume 7, pages 378–381 (2013)Cite this article

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Abstract

Distributing secret keys with information-theoretic security is arguably one of the most important achievements of the field of quantum information processing and communications1. The rapid progress in this field has enabled quantum key distribution in real-world conditions2,3 and commercial devices are now readily available. Quantum key distribution systems based on continuous variables4 provide the major advantage that they only require standard telecommunication technology. However, to date, these systems have been considered unsuitable for long-distance communication5,6,7. Here, we overcome all previous limitations and demonstrate for the first time continuous-variable quantum key distribution over 80 km of optical fibre. All aspects of a practical scenario are considered, including the use of finite-size data blocks for secret information computation and key distillation. Our results correspond to an implementation guaranteeing the strongest level of security for quantum key distribution reported so far for such long distances and pave the way to practical applications of secure quantum communications.

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Figure 1: Optical layout of the long-distance CVQKD prototype.
Figure 2: Key rate produced by the system after error correction and privacy amplification over 24 h.
Figure 3: Experimental excess noise measured over 24 h with a SNR of 0.17 on Bob's side.

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Acknowledgements

This research was supported by the French National Research Agency, through the FREQUENCY (Fundamental Research in Quantum Networks and Cryptography, ANR-09-BLAN-0410) and HIPERCOM (High Performance Coherent Quantum Communications, 2011-CHRI-006) projects, and by the European Union through the project Q-CERT (Quantum Key Distribution Certification, FP7-PEOPLE-2009-IAPP). P.J. acknowledges support from the ANRT (Agence Nationale de la Recherche et de la Technologie). A.L. was supported by the SNF through the National Centre of Competence in Research ‘Quantum Science and Technology.’

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Authors and Affiliations

  1. LTCI, CNRS – Telecom ParisTech, 46 rue Barrault, Paris, 75013, France

    Paul Jouguet & Eleni Diamanti

  2. SeQureNet, 23 avenue d'Italie, Paris, 75013, France

    Paul Jouguet & Sébastien Kunz-Jacques

  3. Institute for Theoretical Physics, ETH Zurich, Zurich, 8093, Switzerland

    Anthony Leverrier

  4. INRIA Rocquencourt, Domaine de Voluceau, B.P. 105, Le Chesnay Cedex, 78153, France

    Anthony Leverrier

  5. Laboratoire Charles Fabry de l'Institut d'Optique – CNRS – Univ. Paris-Sud 11, 2 avenue Augustin Fresnel, Campus Polytechnique, Palaiseau, 91127, France

    Philippe Grangier

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  1. Paul Jouguet
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  2. Sébastien Kunz-Jacques
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  3. Anthony Leverrier
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  4. Philippe Grangier
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  5. Eleni Diamanti
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Contributions

P.J., S.K.-J. and E.D. conceived the project and developed the experimental setup. P.J. and S.K.-J. collected and analysed the data. A.L. performed the security analysis. P.G. contributed to the initial conception of the project and provided scientific expertise. All authors contributed to writing the manuscript.

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Correspondence to Paul Jouguet.

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The authors declare no competing financial interests.

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Jouguet, P., Kunz-Jacques, S., Leverrier, A. et al. Experimental demonstration of long-distance continuous-variable quantum key distribution. Nature Photon 7, 378–381 (2013). https://doi.org/10.1038/nphoton.2013.63

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