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  • Open Access

Practical routing and criticality in large-scale quantum communication networks

Cillian Harney1,2 and Stefano Pirandola1,*

  • 1Department of Computer Science, University of York, York YO10 5GH, United Kingdom
  • 2nodeQ, 71–75 Shelton Street, Covent Garden, London WC2H 9JQ, United Kingdom

  • *Contact author: stefano.pirandola@york.ac.uk
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Phys. Rev. Research 7, 043168 – Published 17 November, 2025

DOI: https://doi.org/10.1103/vy37-28jc

Abstract

The efficacy of a communication network hinges upon both its physical architecture and the protocols that are employed within it. In the context of quantum communications, there exists a fundamental rate-loss trade-off for point-to-point quantum channels such that the rate for distributing entanglement, secret keys, or quantum states decays exponentially with respect to transmission distance. Quantum networks are the solution to overcome point-to-point limitations, but they simultaneously invite a challenging open question: How should quantum networks be designed to effectively and efficiently guarantee high rates? Now that performance and physical topology are inexorably linked, this question is not easy, but the answer is essential for a future quantum internet to be successful. In this work, we offer crucial insight into this open question for complex optical-fiber quantum networks. Using realistic descriptions of quantum networks via random network models and practical end-to-end routing protocols, we reveal critical phenomena associated with large-scale quantum networks. Our work reveals the weaknesses of applying single-path routing protocols within quantum networks, observing an inability to achieve reliable rates over long distances. Adapting algorithms for multipath routing, we employ an efficient and practical multipath routing algorithm capable of boosting performance while minimizing costly quantum resources.

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Phys. Rev. Research 7, 043168– Published 17 November, 2025
  • Received 17 July 2022
  • Accepted 7 September 2025
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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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