Optimal Design of Practical Quantum Key Distribution Backbones for Securing CoreTransport Networks

Abstract

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 (QKD) 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.

The Evolution of Quantum Key Distribution Networks: On the Road to the Qinternet

“…The escalating cost of nodes and links is regarded as one of the major barriers to the practical deployment of QKD networks. Hence, cost optimization is essential for QKD networks, especially for a QKD backbone network owing to its large scale and hence potentially excessive cost [434]. At the time of writing, almost all the practical QKD backbone networks deployed in the field are trusted relay based QKD networks, where two types of QKD nodes are required, namely the QKD backbone node (QBN) and the QKD relay node (QRN).…”

Influence of Cooling on Quantum Network Deployment

“…Given a graph g, we implement a linear programming algorithm to find the cheapest solution which can support a demand matrix K whose elements K ij represent the key material which node i must exchange with node j. The hop-by-hop keys exchange is modelled as a multicommodity flow 6,16,23 with variables x (i,j) nm describing the amount of key material flowing along the edge (n, m) with source node i and destination node j. The set of all source-destination pairs is K. Each edge has a capacity c warm nm and c cool nm given by Eq.…”

“…Unless otherwise stated, each line is valid for all (i, j) ∈ K and (n, m) ∈ E. The first two constraints combined ensure that the correct link capacity is utilised whereas the other constraints ensure key flow conservation 23 . Sourcedestination pair (i, j) and (j, i) are treated symmetrically mirroring the symmetric key cipher 16 .…”

“…Sharing resources in this manner has been overlooked in studies on QKD equipment placement in optical networks [13][14][15][16] . Consequently, we here establish the benefits of co-locating cooling in a QKD network.…”

Topological optimization of hybrid quantum key distribution networks

“…The necessity of credibility control and the variety of QKD protocols, coupled with several intrinsic characteristics of QKD devices, such as the exclusivity of quantum channels and the limitation of key generation capabilities, make the minimum cost calculation of the hybrid QKD network a complex task. In the literature [9] and [10], cost minimization models for QKD networks have been designed under the conditions of link segmentation and and multi-path routing respectively. However, it is difficult to build relay nodes according to the optimal working distance calculated by literature [9].…”