Maximize Quantum Network Throughput via EPS Placement and Lightweight Entanglement Routing

Entanglement routing plays a vital role in supporting various applications in quantum networks. Existing works on entanglement routing either ignored the Entangled Photon Source (EPS) placement issue or simply assumed a pool of EPSes at a centralized location that can provision entanglement over arbitrary quantum links. In this paper, we propose LightER and fidelity-aware LightER (named F-LightER) to solve the joint EPS placement and entanglement routing problem based on the assumption that EPSes are co-located with quantum nodes and each EPS can send one entangled photon at a time to one of its adjacent nodes only. The salient features of LightER and F-LightER include: 1) LightER and F-LightER use a demand-agnostic EPS placement scheme to maximize network throughput and fairness for all feasible Entanglement Connection (EC) establishment demands; and 2) most requested ECs can be established over Entanglement Paths (EPs) determined offline, and only a small percentage of them will be established over online calculated EPs, resulting in fast and efficient entanglement routing. Extensive simulations show that compared with schemes without proper EPS placement or entanglement routing, LightER can improve the network throughput by up to 175.6% and 37.0%, respectively. When the fidelity is considered, the network throughput improvement achieved by F-LightER will be up to 135.0% and 21.5%, respectively.