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600-km repeater-like quantum communications with dual-band stabilization

Nature Photonics volume 15, pages 530–535 (2021)Cite this article

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Abstract

Twin-field (TF) quantum key distribution (QKD) fundamentally alters the rate-distance relationship of QKD, offering the scaling of a single-node quantum repeater. Although recent experiments have demonstrated the new opportunities for secure long-distance communications allowed by TF-QKD, formidable challenges remain to unlock its true potential. Previous demonstrations have required intense stabilization signals at the same wavelength as the quantum signals, thereby unavoidably generating Rayleigh scattering noise that limits the distance and bit rate. Here, we introduce a dual-band stabilization scheme that overcomes past limitations and can be adapted to other phase-sensitive single-photon applications. Using two different optical wavelengths multiplexed together for channel stabilization and protocol encoding, we develop a setup that provides repeater-like key rates over communication distances of 555 km and 605 km in the finite-size and asymptotic regimes respectively and increases the secure key rate at long distance by two orders of magnitude to values of practical relevance.

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Fig. 1: Experimental setup.
Fig. 2: Dual-band stabilization.
Fig. 3: Key rate simulations and results.
Fig. 4: Binary maps of the extracted bit strings.

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Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding authors on reasonable request.

Code availability

The codes used to process the data for this paper are available from the corresponding authors on reasonable request.

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Acknowledgements

We thank X.-B. Wang and H. Xu for their useful feedback on the TWCC protocol. We acknowledge funding from the European Union’s Horizon 2020 research and innovation programme under the grant agreement number 857156 ‘OPENQKD’ and under the Marie Skłodowska-Curie grant agreement number 675662. M.M. acknowledges financial support from the Engineering and Physical Sciences Research Council (EPSRC) and Toshiba Europe Limited.

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Author notes

  1. These authors contributed equally: Mirko Pittaluga, Mariella Minder.

Authors and Affiliations

  1. Toshiba Europe Limited, Cambridge, UK

    Mirko Pittaluga, Mariella Minder, Marco Lucamarini, Mirko Sanzaro, Robert I. Woodward, Zhiliang Yuan & Andrew J. Shields

  2. School of Electronic and Electrical Engineering, University of Leeds, Leeds, UK

    Mirko Pittaluga

  3. Department of Engineering, Cambridge University, Cambridge, UK

    Mariella Minder

  4. Department of Physics and York Centre for Quantum Technologies, University of York, York, UK

    Marco Lucamarini

  5. Corning Incorporated, Corning, NY, USA

    Ming-Jun Li

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  1. Mirko Pittaluga
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Contributions

M.P. and M.M. developed the experimental setup, performed the measurements and analysed the data. M.S. and R.I.W. supported the experimental work. M.-J.L. provided the ultralow-loss fibres. Z.Y., M.L. and A.J.S. guided the work. M.L., M.P. and M.M. provided the simulations and wrote the manuscript, with contributions from all the authors.

Corresponding authors

Correspondence to Mirko Pittaluga or Marco Lucamarini.

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The authors declare no competing interests.

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Peer review information Nature Photonics thanks Guilherme B. Xavier and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Information

Supplementary discussion, Figs. 1–3 and Tables 1–9.

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Pittaluga, M., Minder, M., Lucamarini, M. et al. 600-km repeater-like quantum communications with dual-band stabilization. Nat. Photon. 15, 530–535 (2021). https://doi.org/10.1038/s41566-021-00811-0

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