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Satellite-to-ground quantum key distribution

Abstract

Quantum key distribution (QKD) uses individual light quanta in quantum superposition states to guarantee unconditional communication security between distant parties. However, the distance over which QKD is achievable has been limited to a few hundred kilometres, owing to the channel loss that occurs when using optical fibres or terrestrial free space that exponentially reduces the photon transmission rate. Satellite-based QKD has the potential to help to establish a global-scale quantum network, owing to the negligible photon loss and decoherence experienced in empty space. Here we report the development and launch of a low-Earth-orbit satellite for implementing decoy-state QKD—a form of QKD that uses weak coherent pulses at high channel loss and is secure because photon-number-splitting eavesdropping can be detected. We achieve a kilohertz key rate from the satellite to the ground over a distance of up to 1,200 kilometres. This key rate is around 20 orders of magnitudes greater than that expected using an optical fibre of the same length. The establishment of a reliable and efficient space-to-ground link for quantum-state transmission paves the way to global-scale quantum networks.

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Figure 1: Illustration of the experimental set-up.
Figure 2: Establishing a reliable space-to-ground link for quantum state transfer.
Figure 3: Performance of satellite-to-ground QKD during one orbit.
Figure 4: QKD link efficiencies.

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References

  1. Bennett, C. H. & Brassard, G. Quantum cryptography: public key distribution and coin tossing. In Proc. Int. Conf. on Computers, Systems and Signal Processing 175–179 (1984)

  2. Shannon, C. E. Communication theory of secrecy systems. Bell Syst. Tech. J. 28, 656–715 (1949)

    Article  MathSciNet  Google Scholar 

  3. Bennett, C. H. & Brassard, G. Experimental quantum cryptography: the dawn of a new era for quantum cryptography: the experimental prototype is working! ACM Sigact News 20, 78–80 (1989)

    Article  Google Scholar 

  4. Wootters, W. K. & Zurek, W. H. A single quantum cannot be cloned. Nature 299, 802–803 (1982)

    Article  ADS  CAS  Google Scholar 

  5. Yin, H.-L. et al. Measurement-device-independent quantum key distribution over a 404 km optical fiber. Phys. Rev. Lett. 117, 190501 (2016)

    Article  ADS  Google Scholar 

  6. Brassard, G., Lütkenhaus, N., Mor, T. & Sanders, B. C. Limitations on practical quantum cryptography. Phys. Rev. Lett. 85, 1330–1333 (2000)

    Article  ADS  CAS  Google Scholar 

  7. Briegel, H.-J., Dür, W., Cirac, J. I. & Zoller, P. Quantum repeaters: the role of imperfect local operations in quantum communication. Phys. Rev. Lett. 81, 5932–5935 (1998)

    Article  ADS  CAS  Google Scholar 

  8. Z˙ukowski, M., Zeilinger, A., Horne, M. A. & Ekert, A. K. ‘Event-ready-detectors’ Bell experiment via entanglement swapping. Phys. Rev. Lett. 71, 4287–4290 (1993)

    Article  ADS  Google Scholar 

  9. Bennett, C. H. et al. Purification of noisy entanglement and faithful teleportation via noisy channels. Phys. Rev. Lett. 76, 722–725 (1996)

    Article  ADS  CAS  Google Scholar 

  10. Duan, L.-M., Lukin, M. D., Cirac, J. I. & Zoller, P. Long-distance quantum communication with atomic ensembles and linear optics. Nature 414, 413–418 (2001)

    Article  ADS  CAS  Google Scholar 

  11. Pan, J.-W., Bouwmeester, D., Weinfurter, H. & Zeilinger, A. Experimental entanglement swapping: entangling photons that never interacted. Phys. Rev. Lett. 80, 3891–3894 (1998)

    Article  ADS  MathSciNet  CAS  Google Scholar 

  12. Pan, J.-W., Gasparoni, S., Ursin, R., Weihs, G. & Zeilinger, A. Experimental entanglement purification of arbitrary unknown states. Nature 423, 417–422 (2003)

    Article  ADS  CAS  Google Scholar 

  13. Yang, S.-J., Wang, X.-J., Bao, X.-H. & Pan, J.-W. An efficient quantum light–matter interface with sub-second lifetime. Nat. Photon. 10, 381–384 (2016)

    Article  ADS  CAS  Google Scholar 

  14. Chou, C.-W. et al. Functional quantum nodes for entanglement distribution over scalable quantum networks. Science 316, 1316–1320 (2007)

    Article  ADS  CAS  Google Scholar 

  15. Yuan, Z.-S. et al. Experimental demonstration of a BDCZ quantum repeater node. Nature 454, 1098–1101 (2008)

    Article  ADS  CAS  Google Scholar 

  16. Sangouard, N., Simon, C., De Riedmatten, H. & Gisin, N. Quantum repeaters based on atomic ensembles and linear optics. Rev. Mod. Phys. 83, 33–80 (2011)

    Article  ADS  Google Scholar 

  17. Ritter, S. et al. An elementary quantum network of single atoms in optical cavities. Nature 484, 195–200 (2012)

    Article  ADS  CAS  Google Scholar 

  18. Bernien, H. et al. Heralded entanglement between solid-state qubits separated by three metres. Nature 497, 86–90 (2013)

    Article  ADS  CAS  Google Scholar 

  19. Rarity, J. G., Tapster, P. R., Gorman, P. M. & Knight, P. Ground to satellite secure key exchange using quantum cryptography. New J. Phys. 4, 82 (2002)

    Article  ADS  Google Scholar 

  20. Peng, C.-Z. et al. Experimental free-space distribution of entangled photon pairs over 13 km: towards satellite-based global quantum communication. Phys. Rev. Lett. 94, 150501 (2005)

    Article  ADS  Google Scholar 

  21. Ursin, R. et al. Entanglement-based quantum communication over 144 km. Nat. Phys. 3, 481–486 (2007)

    Article  CAS  Google Scholar 

  22. Yin, J. et al. Quantum teleportation and entanglement distribution over 100-kilometre free-space channels. Nature 488, 185–188 (2012)

    Article  ADS  CAS  Google Scholar 

  23. Ma, X.-S. et al. Quantum teleportation over 143 kilometres using active feed-forward. Nature 489, 269–273 (2012)

    Article  ADS  CAS  Google Scholar 

  24. Wang, J.-Y. et al. Direct and full-scale experimental verifications towards ground–satellite quantum key distribution. Nat. Photon. 7, 387–393 (2013)

    Article  ADS  CAS  Google Scholar 

  25. Nauerth, S. et al. Air-to-ground quantum communication. Nat. Photon. 7, 382–386 (2013)

    Article  ADS  CAS  Google Scholar 

  26. Yin, J. et al. Experimental quasi-single-photon transmission from satellite to earth. Opt. Express 21, 20032–20040 (2013)

    Article  ADS  Google Scholar 

  27. Vallone, G. et al. Experimental satellite quantum communications. Phys. Rev. Lett. 115, 040502 (2015)

    Article  ADS  Google Scholar 

  28. Wang, X.-B. Beating the photon-number-splitting attack in practical quantum cryptography. Phys. Rev. Lett. 94, 230503 (2005)

    Article  ADS  Google Scholar 

  29. Lo, H.-K., Ma, X. & Chen, K. Decoy state quantum key distribution. Phys. Rev. Lett. 94, 230504 (2005)

    Article  ADS  Google Scholar 

  30. Liao, S.-K. et al. Long-distance free-space quantum key distribution in daylight towards inter-satellite communication. Nat. Photon. 11, 509–513 (2017)

    Article  CAS  Google Scholar 

  31. Chen, T.-Y. et al. Metropolitan all-pass and inter-city quantum communication network. Opt. Express 18, 27217–27225 (2010)

    Article  ADS  Google Scholar 

  32. Curty, M. et al. Finite-key analysis for measurement-device-independent quantum key distribution. Nat. Commun. 5, 3732 (2014)

    Article  ADS  CAS  Google Scholar 

  33. Wang, X.-B., Yang, L., Peng, C.-Z. & Pan, J.-W. Decoy-state quantum key distribution with both source errors and statistical fluctuations. New J. Phys. 11, 075006 (2009)

    Article  ADS  Google Scholar 

Download references

Acknowledgements

We thank many colleagues at the National Space Science Center, especially B.-M. Xu, J. Li, J.-C. Gong, B. Chen and J. Liu for their management and coordination. We thank X.-F. Ma, C. Jiang, L. Li, X.-M. Zhang and Y.-W. Chen for discussions. This work was supported by the Strategic Priority Research Program on Space Science, Chinese Academy of Sciences, and the National Natural Science Foundation of China.

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Authors and Affiliations

Authors

Contributions

C.-Z.P. and J.-W.P. conceived the research. C.-Z.P., J.-Y.W. and J.-W.P. designed the experiments. S.-K.L., W.-Q.C., Y.L., C.-Z.P. and J.-W.P. developed the spaceborn QKD source. S.-K.L., W.-Q.C., L.Z., J.Y., J.-J.J., J.-C.W., L.D., Y.-L.Z., Z.-C.Z., R.S., C.-Z.P., J.-Y.W. and J.-W.P. designed and developed the satellite and payloads. S.-K.L., L.Z., J.-J.J., R.S., C.-Z.P. and J.-Y.W. developed the ATP technique. S.-K.L., J.Y., L.Z., C.-Z.P. and J.-W.P. developed the polarization compensation method. X.-B.W. contributed to the decoy-state analysis. C.-Y.L., C.-Z.P. and J.-W.P. analysed the data and wrote the manuscript, with input from S.-K.L., W.-Y.L., Q.S., Y.L. and F.-Z.L. All authors contributed to the data collection, discussed the results and reviewed the manuscript. J.-W.P. supervised the whole project.

Corresponding authors

Correspondence to Cheng-Zhi Peng, Jian-Yu Wang or Jian-Wei Pan.

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Extended data figures and tables

Extended Data Figure 1 Summary of the QKD data obtained for 23 different days.

The x axis is the shortest satellite-to-station distance, which occurs at the highest elevation angle and varies for different days. The y axis is the average sifted key rate that is obtained over the 273-s orbit. The inset shows the quantum bit error rate.

Extended Data Figure 2 The Micius satellite and the payloads.

a, A full view of the Micius satellite before being assembled into the rocket. b, The experimental control box. c, The APT control box. d, The optical transmitter. e, Left side view of the optical transmitter optics head. f, Top side view of the optical transmitter optics head.

Extended Data Figure 3 Hardware at Xinglong ground station.

a, The two-axis gimbal telescope. b, Beacon laser and coarse camera. c, One of the two layers of the optical receiver box.

Extended Data Figure 4 Sketch of the tracking systems on the satellite and at the ground station.

DM1: dichroic mirror transmitting 671-nm light and reflecting 850-nm light. DM2: transmitting 532-nm light; reflecting 671-nm light. DM3: transmitting 532-nm light; reflecting 850-nm light.

Extended Data Figure 5 A typical temporal distribution of 850-nm photons and the measured far-field pattern.

a, A typical temporal distribution of 850-nm photons after the time synchronization process. The data measurement time is 1 s. Each time bin is 100 ps. The counts are normalized and a variance of δ = 0.5 ns is obtained with Gaussian fitting. b, Far-field pattern measured from the thermal-vacuum test on the ground. The divergence angles (full angle at 1/e2 maximum) are 8 μrad for the X axis and 11 μrad for the Y axis. c, Far-field pattern measured from the satellite-to-ground scanning test. The divergence angles (full angle at 1/e2 maximum) are 9 μrad for the X axis and 11 μrad for the Y axis.

Extended Data Figure 6 The experimental procedure.

a, Instruction and data processes. b, Tracking and QKD processes during an orbit.

Extended Data Table 1 Performance of the APT systems
Extended Data Table 2 QKD data of 23 different orbits from 23 September 2016 to 22 May 2017
Extended Data Table 3 Performance of the transmitter and receiver
Extended Data Table 4 Observed data for a single orbit at Xinglong station

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Liao, SK., Cai, WQ., Liu, WY. et al. Satellite-to-ground quantum key distribution. Nature 549, 43–47 (2017). https://doi.org/10.1038/nature23655

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