Oxford links different atom species across a quantum network

Oxford physicists reported a mixed-species quantum network on October 15. Two locations each contain strontium and calcium ions. An optical link entangles strontium ions, and local operations extend that entanglement to calcium memory ions.

The team creates states involving up to four atoms across the locations and preserves distributed entanglement for more than ten seconds. Separating networking and storage roles lets the system use different physical strengths of the two elements.

The experiment demonstrates small-network operations and storage. Building a useful distributed computer also requires reliable repeated connections and coordinated computation across a much larger collection of nodes.