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  • Open Access

Spanning-tree-packing protocol for conference-key propagation in quantum networks

Anton Trushechkin1,2,*, Hermann Kampermann1, and Dagmar Bruß1

  • *Contact author: anton.trushechkin@hhu.de
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Phys. Rev. Applied 25, 034018 – Published 5 March, 2026

DOI: https://doi.org/10.1103/dhqb-k7tl

Abstract

We consider a network of users connected by pairwise quantum key distribution (QKD) links. Using these pairwise secret keys and public classical communication, the users want to generate a common (conference) secret key at the maximal rate. We propose an algorithm based on spanning-tree packing (a known problem in graph theory) and prove its optimality. This algorithm enables optimal conference-key generation in modern quantum networks of arbitrary topology. Additionally, we discuss how it can guide the optimal placement of new bipartite links in the network design.

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Phys. Rev. Applied 25, 034018– Published 5 March, 2026
  • Received 7 August 2025
  • Revised 4 January 2026
  • Accepted 29 January 2026
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