The past decade has seen tremendous progress in experimentally realizing the building blocks of quantum repeaters. Repeater architectures with multiplexed quantum memories have been proposed to increase entanglement distribution rates, but an open challenge is to maintain entanglement fidelity over long-distance links.
A team of researchers has addressed this topic with a quantum router architecture comprising many quantum memories connected in a photonic switchboard to broker entanglement flows across quantum networks.
They have computed the rate and fidelity of entanglement distribution under this architecture using an event-based simulator, finding that the router improves the entanglement fidelity as multiplexing depth increases without a significant drop in the entanglement distribution rate.
Specifically, the router permits channel-loss-invariant fidelity, i.e. the same fidelity achievable with lossless links. Furthermore, this scheme automatically prioritizes entanglement flows across the full network without requiring global network information.
The proposed architecture uses present-day photonic technology, opening a path to near-term deployable multi-node quantum networks.
The paper has been published in npj Quantum.