Optimal Routing for Quantum Networks

TLDR

Quantum computing demands new solutions, and optimal routing—jointly designing protocols and metrics to maximize quantum communication between devices—is essential. The paper addresses optimal routing for generic quantum networks with atom‑cavity repeaters and proposes an optimal routing protocol based on entanglement rate. The authors model entanglement generation stochastically, derive a closed‑form end‑to‑end entanglement rate for any path, and design an efficient algorithm to compute it. They derive a closed‑form end‑to‑end entanglement rate, provide an efficient computation algorithm, and prove that the proposed routing protocol is optimal when using this rate as the routing metric.

Abstract

To fully unleash the potentials of quantum computing, several new challenges and open problems need to be addressed. From a routing perspective, the optimal routing problem, i.e., the problem of jointly designing a routing protocol and a route metric assuring the discovery of the route providing the highest quantum communication opportunities between an arbitrary couple of quantum devices, is crucial. In this paper, the optimal routing problem is addressed for generic quantum network architectures composed by repeaters operating through single atoms in optical cavities. Specifically, we first model the entanglement generation through a stochastic framework that allows us to jointly account for the key physical-mechanisms affecting the end-to-end entanglement rate, such as decoherence time, atom-photon and photon-photon entanglement generation, entanglement swapping, and imperfect Bell-state measurement. Then, we derive the closed-form expression of the end-to-end entanglement rate for an arbitrary path and we design an efficient algorithm for entanglement rate computation. Finally, we design a routing protocol and we prove its optimality when used in conjunction with the entanglement rate as routing metric.