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A photonic integrated quantum secure communication system


Photonic integrated circuits hold great promise in enabling the practical wide-scale deployment of quantum communications; however, despite impressive experiments of component functionality, a fully operational quantum communication system using photonic chips is yet to be demonstrated. Here we demonstrate an entirely standalone secure communication system based on photonic integrated circuits—assembled into compact modules—for quantum random number generation and quantum key distribution at gigahertz clock rates. The bit values, basis selection and decoy pulse intensities used for quantum key distribution are chosen at random, and are based on the output of a chip-based quantum random number generator operating at 4 Gb s–1. Error correction and privacy amplification are performed in real time to produce information-theoretic secure keys for a 100 Gb s–1 line speed data encryption system. We demonstrate long-term continuous operation of the quantum secured communication system using feedback controls to stabilize the qubit phase and propagation delay over metropolitan fibre lengths. These results mark an important milestone for the realistic deployment of quantum communications based on quantum photonic chips.

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Fig. 1: Integrated QKD system comprising a QKD transmitter unit (Alice) interfaced with a QKD receiver unit (Bob) and local servers.
Fig. 2: QKD chips, modules and circuits.
Fig. 3: Real-time pattern generation from quantum random numbers.
Fig. 4: Performance and long-term stability.
Fig. 5: Applicability of the photonic integrated QKD system.

Data availability

The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.


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We thank M. Lucamarini and P. R. Smith for fruitful discussions. This work has been funded by the Innovate UK project AQUASEC, as part of the UK National Quantum Technologies Programme. I.D.M. acknowledges funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 675662.

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Authors and Affiliations



T.K.P., T.R., M.S., D.G.M., Z.Y. and A.J.S. conceived the experiment. T.K.P., T.R., M.S and D.G.M. developed the photonic integrated modules. T.R., I.D.M. and T.K.P. characterized the photonic modules. D.G.M. characterized and optimized the QRNG units. M.S. and D.G.M. developed the QKD and QRNG control electronics. T.R. assembled the systems, developed the stabilization routines and acquired the long-term data. R.I.W and J.F.D. assisted with the installation of the data encryption systems. All authors contributed to the data analysis. T.K.P. wrote the manuscript with contributions from all authors. T.K.P., Z.Y. and A.J.S. supervised the project.

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Correspondence to Taofiq K. Paraïso.

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The authors declare no competing interests.

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

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Supplementary Information

Supplementary Notes 1–4, Figs. 1–6 and Tables 1–3.

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Paraïso, T.K., Roger, T., Marangon, D.G. et al. A photonic integrated quantum secure communication system. Nat. Photon. 15, 850–856 (2021).

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