Abstract
A quantum network1,2,3 provides an infrastructure that connects quantum devices with revolutionary computing, sensing and communication capabilities. A quantum satellite constellation offers a solution to facilitate the quantum network on a global scale4,5. The Micius satellite has verified the feasibility of satellite quantum communications6,7,8,9; however, scaling up quantum satellite constellations is challenging, requiring small lightweight satellites, portable ground stations and real-time secure key exchange. Here we tackle these challenges and report the development of a quantum microsatellite capable of performing space-to-ground quantum key distribution using portable ground stations. The microsatellite payload weighs approximately 23 kilograms, and the portable ground station weighs about 100 kilograms, representing reductions by more than 1 and 2 orders of magnitude, respectively. Using this set-up, we demonstrate satellite-based quantum key distribution with multiple ground stations and achieve the sharing of up to 1.07 million bits of secure keys during a single satellite pass. In addition, we multiplex bidirectional satellite–ground optical communication with quantum communication, enabling key distillation and secure communication in real time. Also, a secret key, enabling one-time pad encryption of images, is created between China and South Africa at locations separated by over 12,900 kilometres on Earth. The compact quantum payload can be readily assembled on existing space stations10,11 or small satellites12, paving the way for a satellite-constellation-based quantum and classical network for widespread real-life applications.
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Data availability
The data that support the findings of this study are available at Zenodo at https://doi.org/10.5281/zenodo.14732295 (ref. 61).
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Acknowledgements
We thank W.-S. Tang, C.-W. Feng, J.-S. Dai, T.-T. Wang, T. Tang, Y.-C. Ji, S.-Q. Fan and Z. Wang for their efforts in the development of the payloads and the microsatellite; H.-B. Li, Z. Wang, W.-W. Ye, S.-J. Xu, X. Li, X. Han, Z.-G. Xiao, L.-K. Guo, C.-F Zhu and Y.-Y. Wang for their long-term assistance in observations and experimental measurements; Q.-Y. Yao, S.-Q. Zhao and Y.-G. Zhao for their efforts in the development of the portable OGSs; and Z.-Y. Chen, C.-L. Li and L.-Y. Han for discussions. This work was supported by National Natural Science Foundation of China (92476203, T2125010, 61961146002, 12174374, 92476001, 12374475 and 62031024), National Key Research and Development Program of China (2020YFA0309701 and 2018YFE0200600), Key R&D Plan of Shandong Province (2021ZDPT01), Jinan Innovation Zone, Innovation Program for Quantum Science and Technology (2021ZD0300104, 2021ZD0300108 and 2021ZD0300300) and Shanghai Municipal Science and Technology Major Project (2019SHZDZX01).
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C.-Z.P. and J.-W.P. conceived the research. S.-K.L., C.-Z.P. and J.-W.P. designed the experiment. Y.L., S.-K.L., Y.-H.L, J.Y. and C.-Z.P. developed the compact QKD light source. L.Z., H.-Y.W., J.-C.W., T.C., S.-K.L. and C.-Z.P. developed the satellite tracking technique. M.Y., C.-Z.W., Y.L., W.-Q.C., S.-K.L. and C.-Z.P. developed the multiplexed quantum and classical communication. S.-K.L., Y.L., W.-Q.C., C.-Z.W., M.Y., L.Z., H.-Y.W., L.C., J.-C.W., X.-Y.T., T.C., C.-F.L., J.Z., F.-Z.L., W.-Y.L., J.Y., R.S., C.-Z.P., J.-Y.W. and J.-W.P. developed the satellite and payloads. J.-G.R., B.J., H.-J.X., X.-J.L., H.L., G.-W.Y., H.-L.Y., Y.C., J.Y., S.-K.L., C.-Z.P. and J.-W.P. developed the portable OGSs. X.-B.W., C.J. and C.-Z.W. contributed to the decoy-state analysis. S.-K.L., Y.L., J.-G.R., B.J., H.-L.Y., W.-Q.C., C.-Z.W., M.Y., L.Z., H.-Y.W., C.W., F.-Z.L., W.-B.L., Y.I., F.P., H.-Z.C., X.-H.T., S.-J.X., F.Z., N.-L.L., L.L., Y.C., J.Y., Q.Z., C.-Z.P. and J.-W.P. contributed to the experiment such as data collection. Y.L., S.-K.L., F.X., Q.Z., C.-Z.P. and J.-W.P. analysed the data and wrote the paper, with input from C.-Z.W., M.Y., L.Z., B.J., H.-L.Y. and C.J. J.-W.P. supervised the whole project.
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Extended data figures and tables
Extended Data Fig. 1 Schematic of the polarization compensation process on the Poincaré sphere.
a, The first QWP moves the corresponding point \({R}^{{\prime} }\) to the equatorial plane, where the corresponding points \({D}^{{\prime} }\) and \({H}^{{\prime} }\) will appear on a warp coil. The central axis for rotation is the projection axis of \(o{R}^{{\prime} }\) (o is the original point) on the equatorial plane. b, The second QWP moves the corresponding point \({H}^{{\prime} }\) to the equatorial plane, where the corresponding point \({R}^{{\prime} }\) will be in the pole position. The central axis for rotation is the projection axis of \(o{H}^{{\prime} }\) on the equatorial plane. c, The HWP moves the corresponding point \({H}^{{\prime} }\) to the original position of point H. The central axis for rotation is the middle axis of \(o{H}^{{\prime} }\) and oH. d, The corresponding points \({R}^{{\prime} }\), \({H}^{{\prime} }\) and \({D}^{{\prime} }\) will return to their original positions of R, H and D (\({R}^{{\prime} }\) coincides with R, \({H}^{{\prime} }\) coincides with H, \({D}^{{\prime} }\) coincides with D. The three wave plates help realize the previous unitary transformation process \({U}^{{\prime} }\).
Extended Data Fig. 2 QBER contribution of noise and satellite elevation angle as functions of time.
The transmitted vacuum state allows for the assessment of the polarization-independent QBER arising from factors such as background noise. In urban environments, background noise is a dominant contributor to the QBER, particularly at low satellite elevation angles where received photon counts are reduced. This impact varies depending on ground station location, time of day, and weather conditions. Employing spectral filtering with narrower linewidth and spatial filtering with smaller field of view can further mitigate this issue.
Extended Data Fig. 3 Method of satellite attitude control.
We incorporate the detected uplink beacon laser of the capture camera into the closed loop of satellite attitude control to achieve precise satellite attitude control.
Extended Data Fig. 4 Laser communication principles.
a, Hardware schematic for laser communication. b, Implementation of time synchronization using laser communication. FPGA, field programmable gate array; CDR, clock and data recovery; EDFA, erbium-doped fiber amplifier.
Extended Data Fig. 5 Procedure of laser-communication-based time synchronization and key distillation.
RND, random number; TDC, time-to-digital converter; LDPC, low-density parity check; CRC, cyclic redundancy check.
Extended Data Fig. 6 Illustration of the processes of key relay and encrypted communication between Jinan station and Nanshan station within two satellite orbits.
a, Key relay. b, Encrypted communication. By leveraging the satellite as a trusted relay, both key relay and encrypted communication can be realized between the two OGSs.
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Li, Y., Cai, WQ., Ren, JG. et al. Microsatellite-based real-time quantum key distribution. Nature 640, 47–54 (2025). https://doi.org/10.1038/s41586-025-08739-z
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DOI: https://doi.org/10.1038/s41586-025-08739-z
