Spanning-tree-packing protocol for conference key propagation in quantum networks
This work provides a theoretically optimal solution for conference key propagation in quantum networks, addressing a key problem for secure multi-party communication.
The paper proposes an algorithm based on spanning-tree packing for optimal conference key generation in quantum networks of arbitrary topology, proving its optimality and discussing its use in network design.
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.