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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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.
All relevant codes or algorithms are available from the corresponding author upon reasonable request.
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The authors declare no competing interests.
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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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