Multipartite multiplexing strategies for quantum routers

Abstract

This work explores the important role of quantum routers in communication networks and investigates the increase in efficiency using memories and multiplexing strategies. Motivated by the bipartite setup introduced by Abruzzo et al. [Phys. Rev. A 89, 012303 (2014)] for finite-range multiplexing in quantum repeaters, we extend the study to an $N$-partite network with a router as a central station. We present a general protocol for $N$ parties after defining the underlying matching problem and we calculate the router rate for different $N$. We analyze the improvement due to multiplexing and analyze the secret key rate with explicit results for the tripartite network. Investigating strategic qubit selection for the Greenberger-Horne-Zeilinger measurements, we show that using cutoffs to remove qubits after a certain number of rounds and consistently combining qubits with the lowest number of storage rounds leads to an optimal secret key rate.