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Towards satellite-based quantum-secure time transfer

Abstract

High-precision time synchronization for remote clocks plays an important role in fundamental science1,2,3 and real-life applications4,5. However, current time synchronization techniques6,7 have been shown to be vulnerable to sophisticated adversaries8. There is a compelling need for fundamentally new methods to distribute high-precision time information securely. Here, we propose a satellite-based quantum-secure time transfer (QSTT) scheme based on two-way quantum key distribution in free space and experimentally verify the key technologies of the scheme via the Micius quantum satellite. In QSTT, a quantum signal (for example, a single photon) is used as the carrier for both the time transfer and the secret-key generation, offering quantum-enhanced security for transferring the time signal and time information. We perform a satellite-to-ground time synchronization using single-photon-level signals and achieve a quantum bit error rate of less than 1%, a time data rate of 9 kHz and a time-transfer precision of 30 ps. These results offer possibilities towards an enhanced infrastructure for a time-transfer network, whose security stems from quantum physics.

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Fig. 1: Schematic of satellite-based QSTT.
Fig. 2: Experimental set-up.
Fig. 3: QBER in the downlink and statistics of the secure two-way time events.
Fig. 4: Satellite-based time-transfer results.

Data availability

Source data are available for this paper. All other data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

Code availability

All relevant codes or algorithms are available from the corresponding author upon reasonable request.

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Authors

Contributions

Q.Z., F.X., C.-Z.P. and J.-W.P. conceived the research. Q.S., J.Y., Y.-A.C., Q.Z., F.X., C.-Z.P. and J.-W.P. designed the experiments. F.X. analysed the security. H.D., Q.S., C.-Z.W., S.-L.L., W.-Y.L., W.-Q.C., S.-K.L., J.-G.R., J.Y., Y.-A.C., Q.Z., F.X., C.-Z.P. and J.-W.P. developed the satellite, the payloads and the single-photon time-transfer techniques. H.D., Q.S., C.-Z.W., S.-L.L., W.-Y.L. and W.-Q.C. carried out the experiment with assistance from all other authors. F.X. and J.-W.P. analysed the data and wrote the manuscript, with input from H.D., Q.S., C.-Z.W., Q.Z. and C.-Z.P. All authors contributed to the data collection, discussed the results and reviewed the manuscript.

Corresponding authors

Correspondence to Feihu Xu or Cheng-Zhi Peng or Jian-Wei Pan.

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The authors declare no competing interests.

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Peer review information Nature Physics thanks Alexander Ling and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Note, Fig. 1 and Tables 1 and 2.

Source data

Source Data Fig. 3

Source data for Fig.3 in main text.

Source Data Fig. 4

Source data for Fig. 4a–c in main text.

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Dai, H., Shen, Q., Wang, CZ. et al. Towards satellite-based quantum-secure time transfer. Nat. Phys. 16, 848–852 (2020). https://doi.org/10.1038/s41567-020-0892-y

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