Experimental quantum repeater without quantum memory

Abstract

Quantum repeaters—important components of a scalable quantum internet—enable entanglement to be distributed over long distances. The standard paradigm for a quantum repeater relies on the necessary, demanding requirement of quantum memory. Despite significant progress, the limited performance of quantum memory means that making practical quantum repeaters remains a challenge. Remarkably, a proposed all-photonic quantum repeater avoids the need for quantum memory by harnessing the graph states in the repeater nodes. Here we perform an experimental demonstration of an all-photonic quantum repeater. By manipulating a 12-photon interferometer, we implement a 2 × 2 parallel all-photonic quantum repeater, and observe an 89% enhancement of entanglement-generation rate over standard parallel entanglement swapping. These results provide a new approach to designing repeaters with efficient single-photon sources and photonic graph states, and suggest that the all-photonic scheme represents an alternative path—parallel to matter-memory-based schemes—towards realizing practical quantum repeaters.

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Fig. 1: Overview of the all-photonic quantum repeater protocol.
Fig. 2: Experimental set-up.
Fig. 3: Experimental characterization of the four-photon GHZ state and PCM device.
Fig. 4: Experimental results for the 2 × 2 parallel all-photonic quantum repeater.

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.

References

  1. 1.

    Lo, H.-K., Curty, M. & Tamaki, K. Secure quantum key distribution. Nat. Photon. 8, 595–604 (2014).

  2. 2.

    Bouwmeester, D. et al. Experimental quantum teleportation. Nature 390, 575–579 (1997).

  3. 3.

    Ladd, T. D. et al. Quantum computers. Nature 464, 45–53 (2010).

  4. 4.

    Yin, J. et al. Satellite-based entanglement distribution over 1,200 kilometers. Science 356, 1140–1144 (2017).

  5. 5.

    Liao, S.-K. et al. Satellite-relayed intercontinental quantum network. Phys. Rev. Lett. 120, 030501 (2018).

  6. 6.

    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).

  7. 7.

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

  8. 8.

    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).

  9. 9.

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

  10. 10.

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

  11. 11.

    Pan, J.-W., Simon, C., Brukner, Č. & Zeilinger, A. Entanglement purification for quantum communication. Nature 410, 1067–1070 (2001).

  12. 12.

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

  13. 13.

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

  14. 14.

    Moehring, D. et al. Entanglement of single-atom quantum bits at a distance. Nature 449, 68–71 (2007).

  15. 15.

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

  16. 16.

    Zwerger, M., Dür, W. & Briegel, H. J. Measurement-based quantum repeaters. Phys. Rev. A 85, 062326 (2012).

  17. 17.

    Munro, W., Stephens, A., Devitt, S., Harrison, K. & Nemoto, K. Quantum communication without the necessity of quantum memories. Nat. Photon. 6, 777–781 (2012).

  18. 18.

    Muralidharan, S., Kim, J., Lütkenhaus, N., Lukin, M. D. & Jiang, L. Ultrafast and fault-tolerant quantum communication across long distances. Phys. Rev. Lett. 112, 250501 (2014).

  19. 19.

    Chen, L.-K. et al. Experimental nested purification for a linear optical quantum repeater. Nat. Photon. 11, 695–699 (2017).

  20. 20.

    Xu, P. et al. Two-hierarchy entanglement swapping for a linear optical quantum repeater. Phys. Rev. Lett. 119, 170502 (2017).

  21. 21.

    Kalb, N. et al. Entanglement distillation between solid-state quantum network nodes. Science 356, 928–932 (2017).

  22. 22.

    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).

  23. 23.

    Azuma, K., Tamaki, K. & Lo, H.-K. All-photonic quantum repeaters. Nat. Commun. 6, 6787 (2015).

  24. 24.

    Raussendorf, R. & Briegel, H. J. A one-way quantum computer. Phys. Rev. Lett. 86, 5188–5191 (2001).

  25. 25.

    Bruschi, D. E., Barlow, T. M., Razavi, M. & Beige, A. Repeat-until-success quantum repeaters. Phys. Rev. A 90, 032306 (2014).

  26. 26.

    Pant, M., Krovi, H., Englund, D. & Guha, S. Rate-distance tradeoff and resource costs for all-optical quantum repeaters. Phys. Rev. A 95, 012304 (2017).

  27. 27.

    Buterakos, D., Barnes, E. & Economou, S. E. Deterministic generation of all-photonic quantum repeaters from solid-state emitters. Phys. Rev. X 7, 041023 (2017).

  28. 28.

    Ewert, F., Bergmann, M. & van Loock, P. Ultrafast long-distance quantum communication with static linear optics. Phys. Rev. Lett. 117, 210501 (2016).

  29. 29.

    Ewert, F. & van Loock, P. Ultrafast fault-tolerant long-distance quantum communication with static linear optics. Phys. Rev. A 95, 012327 (2017).

  30. 30.

    Hasegawa, Y. et al. Experimental time-reversed adaptive Bell measurement towards all-photonic quantum repeaters. Nat. Commun. 10, 378 (2019).

  31. 31.

    James, D. F. V., Kwiat, P. G., Munro, W. J. & White, A. G. Measurement of qubits. Phys. Rev. A 64, 052312 (2001).

  32. 32.

    Luis, A. & Sánchez-Soto, L. L. Complete characterization of arbitrary quantum measurement processes. Phys. Rev. Lett. 83, 3573–3576 (1999).

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Acknowledgements

The authors thank H.-K. Lo for helpful discussions. This work was supported by the National Key Research and Development (R&D) Plan of China (grants 2018YFB0504300 and 2018YFA0306501), the National Natural Science Foundation of China (grants 11425417, 61771443 and U1738140), the Anhui Initiative in Quantum Information Technologies and the Chinese Academy of Sciences.

Author information

Z.-D.L., F.X., Y.-A.C. and J.-W.P. conceived and designed the experiments. Z.-D.L., F.X. and Y.-A.C. designed and characterized the multiphoton optical circuits. Z.-D.L., R.Z., X.-F.Y., L.-Z.L., Y.H., Y.-Q.F. and Y.-Y.F. carried out the experiments. Z.-D.L., R.Z., F.X. and Y.-A.C. analysed the data. All authors discussed the results and wrote the manuscript. F.X., Y.-A.C. and J.-W.P. supervised the project.

Correspondence to Feihu Xu or Yu-Ao Chen or Jian-Wei Pan.

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