Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Quantum fusion of independent networks based on multi-user entanglement swapping

Nature Photonics volume 20, pages 87–95 (2026)Cite this article

Subjects

Abstract

With the advanced development of quantum science, constructing a large-scale quantum network has become a prominent area in the future of quantum information technology. Future quantum networks promise to enable a wide range of groundbreaking applications and to unlock fundamentally new technologies in information security and large-scale computation. The future quantum internet is required to connect quantum information processors to achieve unparalleled capabilities in secret communication and enable quantum communication between any two points on Earth. However, existing quantum networks are primarily designed to facilitate communication between end users within their own networks. Bridging different independent networks to form a fully connected quantum internet has become a pressing challenge for future quantum communication systems. Here we demonstrate the quantum fusion of two independent networks based on multi-user entanglement swapping, to merge two 10-user networks into a larger network with 18 users in a quantum correlation layer. By performing Bell state measurements between two non-neighbouring nodes, users from different networks can establish entanglement, allowing all 18 users to ultimately communicate with each other using the swapped states. Our approach opens up promising opportunities for establishing quantum entanglement between remote nodes across different networks, facilitating versatile quantum information interconnects and enabling the construction of large-scale intercity quantum communication networks.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on SpringerLink
  • Instant access to the full article PDF.

USD 39.95

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Scheme of quantum network fusion, network architecture and operation principle.
Fig. 2: Experimental set-up for the network fusion of two fully connected networks.
Fig. 3: Experimental results of the fully connected network constructed using the ATWM scheme.
Fig. 4: Experimental two-photon interference for polarization entanglement between CH31 and other users in the two networks.
Fig. 5: Experimental HOM interference under two different delays.
Fig. 6: Experimental two-photon interference for polarization entanglement after multi-user entanglement swapping.

Similar content being viewed by others

Data availability

All data are available in the article or its Supplementary Information. The data files supporting the plots in the main text are available via figshare at https://figshare.com/s/145209fe661ad4bcd80b (ref. 50). The data that support the findings of this study are available from the corresponding authors upon reasonable request. Source data are provided with this paper.

References

  1. Xu, F., Ma, X., Zhang, Q., Lo, H. K. & Pan, J. W. Secure quantum key distribution with realistic devices. Rev. Mod. Phys. 92, 025002 (2020).

    Article  ADS  MathSciNet  Google Scholar 

  2. Li, W. et al. High-rate quantum key distribution exceeding 110 Mb s−1. Nat. Photonics 17, 416–421 (2023).

    Article  ADS  Google Scholar 

  3. Grünenfelder, F. et al. Fast single-photon detectors and real-time key distillation enable high secret-key-rate quantum key distribution systems. Nat. Photonics 17, 422–426 (2023).

    Article  ADS  Google Scholar 

  4. Humphreys, P. C. et al. Deterministic delivery of remote entanglement on a quantum network. Nature 558, 268–273 (2018).

    Article  ADS  Google Scholar 

  5. Wang, S. et al. Twin-field quantum key distribution over 830-km fibre. Nat. Photonics 16, 154–161 (2022).

    Article  ADS  Google Scholar 

  6. Zhong, Y. et al. Deterministic multi-qubit entanglement in a quantum network. Nature 590, 571–575 (2021).

    Article  ADS  Google Scholar 

  7. Kržič, A. et al. Towards metropolitan free-space quantum networks. NPJ Quantum Inf. 9, 95 (2023).

    Article  ADS  Google Scholar 

  8. Ribezzo, D. et al. Deploying an inter-European quantum network. Adv. Quantum Technol. 6, 2200061 (2023).

    Article  Google Scholar 

  9. Chen, Y. A. et al. An integrated space-to-ground quantum communication network over 4,600 kilometres. Nature 589, 214–219 (2021).

    Article  ADS  Google Scholar 

  10. Li, Y. et al. Multiuser time-energy entanglement swapping based on dense wavelength division multiplexed and sum-frequency generation. Phys. Rev. Lett. 123, 250505 (2019).

    Article  ADS  Google Scholar 

  11. Pompili, M. et al. Realization of a multinode quantum network of remote solid-state qubits. Science 372, 259–264 (2021).

    Article  ADS  Google Scholar 

  12. Wehner, S., Elkouss, D. & Hanson, R. Quantum internet: a vision for the road ahead. Science 362, eaam9288 (2018).

    Article  ADS  MathSciNet  Google Scholar 

  13. Wei, S.-H. et al. Towards real-world quantum networks: a review. Laser Photonics Rev. 16, 2100219 (2022).

    Article  ADS  Google Scholar 

  14. Simon, C. Towards a global quantum network. Nat. Photonics 11, 678–680 (2017).

    Article  ADS  Google Scholar 

  15. Pittaluga, M. et al. Long-distance coherent quantum communications in deployed telecom networks. Nature 640, 911–917 (2025).

    Article  ADS  Google Scholar 

  16. Chang, X. Y. et al. Hybrid entanglement and bit-flip error correction in a scalable quantum network node. Nat. Phys. 21, 583–589 (2025).

    Article  Google Scholar 

  17. Hermans, S. L. N. et al. Qubit teleportation between non-neighbouring nodes in a quantum network. Nature 605, 663–668 (2022).

    Article  ADS  Google Scholar 

  18. Cacciapuoti, A. S. et al. Quantum internet: networking challenges in distributed quantum computing. IEEE Network 34, 137–143 (2019).

    Article  Google Scholar 

  19. Degen, C. L., Reinhard, F. & Cappellaro, P. Quantum sensing. Rev. Mod. Phys. 89, 035002 (2017).

    Article  ADS  MathSciNet  Google Scholar 

  20. Guo, X. et al. Distributed quantum sensing in a continuous-variable entangled network. Nat. Phys. 16, 281–284 (2020).

    Article  Google Scholar 

  21. Polino, E. et al. Experimental nonclassicality in a causal network without assuming freedom of choice. Nat. Commun. 14, 909 (2023).

    Article  ADS  Google Scholar 

  22. Wang, N. N. et al. Certification of non-classicality in all links of a photonic star network without assuming quantum mechanics. Nat. Commun. 14, 2153 (2023).

    Article  ADS  Google Scholar 

  23. Sun, Q. C. et al. Experimental demonstration of non-bilocality with truly independent sources and strict locality constraints. Nat. Photonics 13, 687–691 (2019).

    Article  ADS  Google Scholar 

  24. Wengerowsky, S., Joshi, S. K., Steinlechner, F., Hübel, H. & Ursin, R. An entanglement-based wavelength multiplexed quantum communication network. Nature 564, 225–228 (2018).

    Article  ADS  Google Scholar 

  25. Joshi, S. K. et al. A trusted node-free eight-user metropolitan quantum communication network. Sci. Adv. 6, eaba0959 (2020).

    Article  ADS  Google Scholar 

  26. Liu, X. et al. An entanglement-based quantum network based on symmetric dispersive optics quantum key distribution. APL Photonics 5, 076104 (2020).

    Article  ADS  Google Scholar 

  27. Kim, J. H., Chae, J. W., Jeong, Y. C. & Kim, Y. H. Quantum communication with time-bin entanglement over a wavelength-multiplexed fiber network. APL Photonics 7, 016106 (2022).

    Article  ADS  Google Scholar 

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

    Article  ADS  MathSciNet  Google Scholar 

  29. Samara, F. et al. Entanglement swapping between independent and asynchronous integrated photon-pair sources. Quantum Sci. Technol. 6, 045024 (2021).

    Article  ADS  Google Scholar 

  30. Liu, S., Lou, Y., Chen, Y. & Jing, J. All-optical entanglement swapping. Phys. Rev. Lett. 128, 060503 (2022).

    Article  ADS  Google Scholar 

  31. Kaltenbaek, R., Prevedel, R., Aspelmeyer, M. & Zeilinger, A. High-fidelity entanglement swapping with fully independent sources. Phys. Rev. A 79, 040302 (2009).

    Article  ADS  Google Scholar 

  32. Lu, C. Y., Yang, T. & Pan, J. W. Experimental multiparticle entanglement swapping for quantum networking. Phys. Rev. Lett. 103, 020501 (2009).

    Article  ADS  Google Scholar 

  33. Shchukin, E. & van Loock, P. Optimal entanglement swapping in quantum repeaters. Phys. Rev. Lett. 128, 150502 (2022).

    Article  ADS  MathSciNet  Google Scholar 

  34. Guccione, G. et al. Connecting heterogeneous quantum networks by hybrid entanglement swapping. Sci. Adv. 6, eaba4508 (2020).

    Article  ADS  Google Scholar 

  35. Sun, Q. C. et al. Entanglement swapping over 100 km optical fiber with independent entangled photon-pair sources. Optica 4, 1214–1218 (2017).

    Article  ADS  Google Scholar 

  36. Hong, C. K., Ou, Z. Y. & Mandel, L. Measurement of subpicosecond time intervals between two photons by interference. Phys. Rev. Lett. 59, 2044 (1987).

    Article  ADS  Google Scholar 

  37. Xiong, C. et al. Active temporal multiplexing of indistinguishable heralded single photons. Nat. Commun. 7, 10853 (2016).

    Article  ADS  Google Scholar 

  38. Kwiat, P. G. et al. New high-intensity source of polarization-entangled photon pairs. Phys. Rev. Lett. 75, 4337 (1995).

    Article  ADS  Google Scholar 

  39. Clauser, J. F., Horne, M. A., Shimony, A. & Holt, R. A. Proposed experiment to test local hidden-variable theories. Phys. Rev. Lett. 23, 880 (1969).

    Article  ADS  Google Scholar 

  40. Ma, Z. et al. Ultrabright quantum photon sources on chip. Phys. Rev. Lett. 125, 263602 (2020).

    Article  ADS  Google Scholar 

  41. Fan, Y. et al. Multi-wavelength quantum light sources on silicon nitride micro-ring chip. Laser Photonics Rev. 17, 2300172 (2023).

    Article  ADS  Google Scholar 

  42. Azuma, K. et al. Quantum repeaters: from quantum networks to the quantum internet. Rev. Mod. Phys. 95, 045006 (2023).

    Article  ADS  MathSciNet  Google Scholar 

  43. Liu, J. et al. Creation of memory–memory entanglement in a metropolitan quantum network. Nature 629, 579–585 (2024).

    Article  ADS  Google Scholar 

  44. Knaut, C. M. et al. Entanglement of nanophotonic quantum memory nodes in a telecom network. Nature 629, 573–578 (2024).

    Article  ADS  Google Scholar 

  45. Azuma, K., Tamaki, K. & Lo, H. K. All-photonic quantum repeaters. Nat. Commun. 6, 1–7 (2015).

    Google Scholar 

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

    Article  ADS  Google Scholar 

  47. Li, Z. D. et al. Experimental quantum repeater without quantum memory. Nat. Photonics 13, 644–648 (2019).

    Article  ADS  Google Scholar 

  48. Li, B., Goodenough, K., Rozpędek, F. & Jiang, L. Generalized quantum repeater graph states. Phys. Rev. Lett. 134, 190801 (2025).

    Article  ADS  MathSciNet  Google Scholar 

  49. Zhang, Y. et al. Scalable, fiber-compatible lithium-niobate-on-insulator micro-waveguides for efficient nonlinear photonics. Optica 10, 688–693 (2023).

    Article  ADS  Google Scholar 

  50. Huang, Y. et al. SourceData.zip. figshare https://figshare.com/s/145209fe661ad4bcd80b (2025).

Download references

Acknowledgements

This work is supported in part by the National Natural Science Foundation of China (grant nos. 12192252 and 62375164), the Foundation for Shanghai Municipal Science and Technology Major Project (grant no. 2019SHZDZX01-ZX06), the Shuguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission (grant no. 24SG53), the National Key Research and Development Program of China (grant nos. 2022YFA1205100 and 2023YFA1407200), the Science and Technology Commission of Shanghai Municipality (grant no. 24JD1401700) and the Guangdong Provincial Quantum Science Strategic Initiative (grant no. GDZX2403003).

Author information

Author notes

  1. These authors contributed equally: Yiwen Huang, Yilin Yang, Hao Li.

Authors and Affiliations

  1. State Key Laboratory of Photonics and Communications, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China

    Yiwen Huang, Yilin Yang, Hao Li, Jiayu Wang, Jing Qiu, Zhantong Qi, Yuting Zhang, Yuanhua Li, Yuanlin Zheng & Xianfeng Chen

  2. Department of Physics, Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai, China

    Yuanhua Li

  3. Shanghai Research Center for Quantum Sciences, Shanghai, China

    Yuanlin Zheng & Xianfeng Chen

  4. Collaborative Innovation Center of Light Manipulation and Applications, Shandong Normal University, Jinan, China

    Xianfeng Chen

Authors
  1. Yiwen Huang
    View author publications

    Search author on:PubMed Google Scholar

  2. Yilin Yang
    View author publications

    Search author on:PubMed Google Scholar

  3. Hao Li
    View author publications

    Search author on:PubMed Google Scholar

  4. Jiayu Wang
    View author publications

    Search author on:PubMed Google Scholar

  5. Jing Qiu
    View author publications

    Search author on:PubMed Google Scholar

  6. Zhantong Qi
    View author publications

    Search author on:PubMed Google Scholar

  7. Yuting Zhang
    View author publications

    Search author on:PubMed Google Scholar

  8. Yuanhua Li
    View author publications

    Search author on:PubMed Google Scholar

  9. Yuanlin Zheng
    View author publications

    Search author on:PubMed Google Scholar

  10. Xianfeng Chen
    View author publications

    Search author on:PubMed Google Scholar

Contributions

Y.H. and X.C. conceptualized the idea and designed the experiments. X.C. led the project since its conception. Y.L., Y. Zheng and X.C. supervised all the experiments. Y.H., Y.Y. and Z.Q. performed the experiment and data analysis. J.W., H.L., J.Q. and Y. Zhang developed the device fabrication. All authors participated in discussions of the results. Y.H. prepared the paper with assistance from all other co-authors. Y.Y., Y.L., Y. Zheng and X.C. provided revisions.

Corresponding authors

Correspondence to Yuanhua Li, Yuanlin Zheng or Xianfeng Chen.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Photonics thanks the anonymous reviewer(s) for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–11 and Tables 1–3.

Source data

Source Data Figs. 3–6

Source Data Fig. 3: Experimental results of the fully connected network constructed using the ATWM scheme. Source Data Fig. 4: Experimental two-photon interference for polarization entanglement between CH31 and other users in the two networks. Source Data Fig. 5: Experimental HOM interference under two different delays. Source Data Fig. 6: Experimental two-photon interference for polarization entanglement after multi-user entanglement swapping.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Huang, Y., Yang, Y., Li, H. et al. Quantum fusion of independent networks based on multi-user entanglement swapping. Nat. Photon. 20, 87–95 (2026). https://doi.org/10.1038/s41566-025-01792-0

Download citation

  • Received:

  • Accepted:

  • Published:

  • Version of record:

  • Issue date:

  • DOI: https://doi.org/10.1038/s41566-025-01792-0

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing