Influence of different topologies of the backbone quantum network persistence of unidirectional key transport

In this work, we evaluate how the introduction of additional unidirectional connections through one, two, and so on nodes in the backbone quantum network affects the security of its key transport. Expressions are obtained for the probability of a successful attack depending on the total number of nodes and the number of additional connections for a given average probability of intercepting one node (and corresponding restrictions on the value of the latter). The result clearly demonstrates the trade-off between increasing the security of key transport and increasing the maximum allowable distance for quantum key distribution or increasing the number of nodes at a given maximum allowable distance.