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An integrated silicon photonic chip platform for continuous-variable quantum key distribution


Quantum key distribution (QKD) is a quantum communication technology that promises unconditional communication security. High-performance and cost-effective QKD systems are essential for the establishment of quantum communication networks1,2,3. By integrating all the optical components (except the laser source) on a silicon photonic chip, we have realized a stable, miniaturized and low-cost system for continuous-variable QKD (CV-QKD) that is compatible with the existing fibre optical communication infrastructure4. Here, the integrated silicon photonic chip is demonstrated for CV-QKD. It implements the widely studied Gaussian-modulated coherent state protocol that encodes continuous distributed information on the quadrature of laser light5,6. Our proof-of-principle chip-based CV-QKD system is capable of producing a secret key rate of 0.14 kbps (under collective attack) over a simulated distance of 100 km in fibre, offering new possibilities for low-cost, scalable and portable quantum networks.

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Fig. 1: Schematic of the CV-QKD system.
Fig. 2: Scanning electron microscopy and optical microscopy images of the QKD chip.
Fig. 3: Chip performance analysis.
Fig. 4: Key distribution test.
Fig. 5: Secure key rate analysis.

Data availability

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


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This work was supported by the Singapore Ministry of Education (MOE) Tier 3 grant (MOE2017-T3-1-001), the Singapore National Research Foundation (NRF) National Natural Science Foundation of China (NSFC) joint grant (NRF2017NRF-NSFC002-014) and the Singapore National Research Foundation under the Competitive Research Program (NRF-CRP13-2014-01).

Author information




G.Z., L.C.K. and A.Q.L. jointly conceived the idea. G.Z. and H.C. designed and fabricated the silicon photonic chip. G.Z., Y.Z., S.Y., J.W., W.S., F.X. and X.Z. performed the experiments. J.Y.H., S.M.A., J.F.F. and L.C.K. assisted with the theory. All authors contributed to the discussion of experimental results. F.X., L.C.K. and A.Q.L. supervised and coordinated all the work. G.Z., F.X., L.C.K. and A.Q.L. wrote the manuscript with contributions from all co-authors.

Corresponding authors

Correspondence to F. Xu or L. C. Kwek or A. Q. Liu.

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The authors declare no competing interests.

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Zhang, G., Haw, J.Y., Cai, H. et al. An integrated silicon photonic chip platform for continuous-variable quantum key distribution. Nat. Photonics 13, 839–842 (2019).

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