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

TL;DR

This paper introduces an optimal spanning-tree-based protocol for conference key generation in quantum networks, enhancing efficiency and guiding network design.

Contribution

It proposes a novel algorithm based on spanning-tree packing for optimal conference key propagation in quantum networks of any topology.

Findings

Proves the optimality of the spanning-tree packing algorithm.

Enables maximal rate conference key generation.

Guides the placement of new quantum links in network design.

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.