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High-Rate Scalable Entanglement Swapping Between Remote Entanglement Sources on Deployed New York City Fibers

Alexander N. Craddock1, Tyler Cowan2, Niccolò Bigagli1, Suresh Yekasiri3, Dylan Robinson1, Gabriel Bello Portmann1, Aditya Verma1, Ziyu Guo3, Michael Kilzer3 et al.

Jiapeng Zhao3, Mael Flament1, Javad Shabani2, Reza Nejabati3, and Mehdi Namazi1,*

  • 1Qunnect Inc., 141 Flushing Avenue, Suite 1110, Brooklyn, New York 11205-1005, USA
  • 2Center for Quantum Information Physics, Department of Physics, New York University, New York 10003, USA
  • 3Cisco Quantum Labs, Santa Monica, California 90404, USA

  • *Contact author: mehdi@quconn.com
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PRX Quantum 7, 043028 – Published 10 November, 2026

DOI: https://doi.org/10.1103/4xr6-2w3d

Abstract

Entanglement swapping between photon pairs generated at physically separated nodes over telecommunication fiber infrastructure is an essential step toward the quantum internet, enabling applications such as quantum repeaters, blind quantum computing, distributed quantum computing, and distributed quantum sensing. However, successful networked entanglement swapping relies on generating indistinguishable pairs of photons and preserving them over deployed fibers. This has limited most previous demonstrations to laboratory settings or relied on sophisticated methods to maintain the necessary indistinguishability. Here, we demonstrate a scalable entanglement-swapping experiment using naturally indistinguishable entanglement sources based on warm atomic vapor cells. Without sharing lasers or optical frequency references between nodes, nor the need for pulsing the sources, we achieve a swapping rate of nearly 500 pairs/s in a local configuration while maintaining the Clauser–Horne–Shimony–Holt (CHSH) parameter above 2. Additionally, we demonstrate the scalability of our method by maintaining the quality of the entanglement swapping on 17.6 km of deployed fibers in New York City, relying on commercially available single-photon avalanche detectors at the spoke nodes, superconducting nanowire detectors at the hub and standard time-synchronization techniques. Our work paves the way for the practical deployment of large-scale hub-and-spoke quantum networks within cities and data centers.

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Popular Summary

Creating entanglement between remote photons is an essential step toward quantum repeaters and distributed quantum networks. Here, we demonstrate entanglement swapping between two independent entanglement sources at rates exceeding 470 events per second, demonstrating a path toward high-rate distributed quantum networks. We further show entanglement swapping across three independent nodes connected by 17.6 km of deployed commercial fiber between Brooklyn and Manhattan, achieving Hz-level swapping rates. Both experiments utilize a hub-and-spoke architecture in which the spoke nodes require only commercially available, room-temperature entanglement sources and single-photon detectors. Together, these results demonstrate a practical approach to high-rate entanglement swapping and a scalable architecture for metropolitan quantum networks.

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References (30)

  1. H. J. Kimble, The quantum internet, Nature (London) 453, 1023 (2008).
  2. K. Azuma, S. E. Economou, D. Elkouss, P. Hilaire, L. Jiang, H.-K. Lo, and I. Tzitrin, Quantum repeaters: From quantum networks to the quantum internet, Rev. Mod. Phys. 95 045006 (2023).
  3. C. Monroe, R. Raussendorf, A. Ruthven, K. R. Brown, P. Maunz, L.-M. Duan, and J. Kim, Large-scale modular quantum-computer architecture with atomic memory and photonic interconnects, Phys. Rev. A 89, 022317 (2014).
  4. S. Pirandola and S. L. Braunstein, Physics: Unite to build a quantum internet, Nature (London) 532, 169 (2016).
  5. S. Wehner, D. Elkouss, and R. Hanson, Quantum internet: A vision for the road ahead, Science 362, eaam9288 (2018).
  6. E. T. Khabiboulline, J. Borregaard, K. De Greve, and M. D. Lukin, Optical interferometry with quantum networks, Phys. Rev. Lett. 123, 070504 (2019).
  7. E. Shchukin and P. van Loock, Optimal entanglement swapping in quantum repeaters, Phys. Rev. Lett. 128, 150502 (2022).
  8. R. Kaltenbaek, R. Prevedel, M. Aspelmeyer, and A. Zeilinger, High-fidelity entanglement swapping with fully independent sources, Phys. Rev. A 79, 040302(R) (2009).
  9. N. Sangouard, C. Simon, B. Zhao, Y.-A. Chen, H. de Riedmatten, J.-W. Pan, and N. Gisin, Robust and efficient quantum repeaters with atomic ensembles and linear optics, Phys. Rev. A 77, 062301 (2008).
  10. A. Broadbent, J. Fitzsimons, and E. Kashefi, Universal blind quantum computation, in 2009 50th Annual IEEE Symposium on Foundations of Computer Science (IEEE, NW Washington, DC, United States 2009).
  11. Q. Li, W. H. Chan, C. Wu, and Z. Wen, Triple-server blind quantum computation using entanglement swapping, Phys. Rev. A 89, 040302(R) (2014).
  12. H. Shapourian, E. Kaur, T. Sewell, J. Zhao, M. Kilzer, R. Kompella, and R. Nejabati, Quantum data center infrastructures: A scalable architectural design perspective, arXiv:2501.05598.
  13. S. I. Davis, R. Valivarthi, A. Cameron, C. Pena, S. Xie, L. Narvaez, N. Lauk, C. Li, K. Taylor, R. Youssef, C. Wang, K. Kapoor, B. Korzh, N. Sinclair, M. Shaw, P. Spentzouris, and M. Spiropulu, Entanglement swapping systems toward a quantum internet, arXiv:2503.18906.
  14. Q.-C. Sun, Y.-F. Jiang, Y.-L. Mao, L.-X. You, W. Zhang, W.-J. Zhang, X. Jiang, T.-Y. Chen, H. Li, Y.-D. Huang, X.-F. Chen, Z. Wang, J. Fan, Q. Zhang, and J.-W. Pan, Entanglement swapping over 100 km optical fiber with independent entangled photon-pair sources, Optica 4, 1214 (2017).
  15. F. Basso Basset, M. B. Rota, C. Schimpf, D. Tedeschi, K. D. Zeuner, S. F. Covre da Silva, M. Reindl, V. Zwiller, K. D. Jöns, A. Rastelli, and R. Trotta, Entanglement swapping with photons generated on demand by a quantum dot, Phys. Rev. Lett. 123, 160501 (2019).
  16. J.-W. Pan, D. Bouwmeester, H. Weinfurter, and A. Zeilinger, Experimental entanglement swapping: Entangling photons that never interacted, Phys. Rev. Lett. 80, 3891 (1998).
  17. A. J. Stolk et al., Metropolitan-scale heralded entanglement of solid-state qubits, Sci. Adv. 10, eadp6442 (2024).
  18. W.-Z. Liu et al., Long-lived remote ion-ion entanglement for scalable quantum repeaters, Nature (London) 652, 51 (2026).
  19. J. Park, H. Kim, and H. Seb Moon, Entanglement swapping with autonomous polarization-entangled photon pairs from a warm atomic ensemble, Opt. Lett. 45, 2403 (2020).
  20. R.-B. Jin, M. Takeoka, U. Takagi, R. Shimizu, and M. Sasaki, Highly efficient entanglement swapping and teleportation at telecom wavelength, Sci. Rep. 5, 9333 (2015).
  21. L. J. Stephenson, D. P. Nadlinger, B. C. Nichol, S. An, P. Drmota, T. G. Ballance, K. Thirumalai, J. F. Goodwin, D. M. Lucas, and C. J. Ballance, High-rate, high-fidelity entanglement of qubits across an elementary quantum network, Phys. Rev. Lett. 124, 110501 (2020).
  22. A. N. Craddock, Y. Wang, F. Giraldo, R. Sekelsky, M. Flament, and M. Namazi, High-rate subgigahertz-linewidth bichromatic entanglement source for quantum networking, Phys. Rev. Appl. 21, 034012 (2024).
  23. A. N. Craddock, A. Lazenby, G. B. Portmann, R. Sekelsky, M. Flament, and M. Namazi, Automated distribution of polarization-entangled photons using deployed New York City fibers, PRX Quantum 5, 030330 (2024).
  24. M. Sena, M. Flament, S. Andrewski, I. Caltzidis, N. Bigagli, T. Rieser, G. Bello Portmann, R. Sekelsky, R.-P. Braun, A. N. Craddock, M. Schulz, K. D. Jöns, M. Ritter, M. Geitz, O. Holschke, and M. Namazi, High-fidelity quantum entanglement distribution in metropolitan fiber networks with co-propagating classical traffic, J. Opt. Commun. Netw. 17, 1072 (2025).
  25. Y. Shi, J. Su, A. Rahmouni, P. Shrestha, M. Merzouki, G. B. Portmann, A. Lazenby, M. Flament, M. Namazi, A. Battou, O. Slattery, and T. Gerrits, Entanglement distribution over a polarization-stabilized aerial fiber, arXiv:2601.11753.
  26. D. Mayers and A. Yao, Quantum cryptography with imperfect apparatus, in Proceedings 39th Annual Symposium on Foundations of Computer Science (Cat. No.98CB36280), Palo Alto, CA, USA (1998), pp. 503–509, https://ieeexplore.ieee.org/xpl/conhome/5965/proceeding.
  27. Z. Ye-Qi and X. Jing-Bo, Entanglement swapping of pair coherent states with phase decoherence, Chin. Phys. Lett. 26, 070301 (2009).
  28. S. Vijayaraj and M. Paternostro, Improving device-independent quantum key distribution protocols through multiple routed bell tests, arXiv:2606.26329.
  29. L. Escolà-Farràs, B. Škorić, and F. Speelman, Arbitrarily loss-tolerant quantum position verification in a single execution, arXiv:2606.25037.
  30. C. H. Bennett, G. Brassard, S. Popescu, B. Schumacher, J. A. Smolin, and W. K. Wootters, Purification of noisy entanglement and faithful teleportation via noisy channels, Phys. Rev. Lett. 76, 722 (1996).

Outline

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PRX Quantum 7, 043028– Published 10 November, 2026
  • Received 17 April 2026
  • Revised 13 July 2026
  • Accepted 13 October 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

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