Optimal Design of Practical Quantum Key Distribution Backbones for Securing Core Transport Networks

We describe two Mixed Integer Linear Programming formulations, one a faster version of a previous proposal, the other a slower but better performing new model, for the design of Quantum Key Distribution sub-networks dimensioned to secure existing core fiber plants. We exploit existing technologies, including non-quantum repeater nodes and multiple disjoint QKD paths to overcome reach limitations while maintaining security guarantees. We examine the models' performance using simulations on both synthetic and real topologies, quantifying their time and resulting QKD network cost compared to our previous proposal.