A multinode quantum network over a metropolitan area

TL;DR

This paper reports the first implementation of a multi-node entanglement-based quantum network over a city, demonstrating scalable architecture, entanglement generation, and storage across multiple nodes, advancing quantum internet development.

Contribution

It introduces a multi-node quantum network with atomic memories and telecom interfaces, scalable phase stabilization, and multi-link entanglement, marking a significant step towards practical quantum internet.

Findings

Heralded entanglement between nodes 12.5 km apart

Storage of entanglement exceeding round-trip communication time

Concurrent entanglement generation on three links

Abstract

Towards realizing the future quantum internet, a pivotal milestone entails the transition from two-node proof-of-principle experiments conducted in laboratories to comprehensive, multi-node setups on large scales. Here, we report on the debut implementation of a multi-node entanglement-based quantum network over a metropolitan area. We equipped three quantum nodes with atomic quantum memories and their telecom interfaces, and combined them into a scalable phase-stabilized architecture through a server node. We demonstrated heralded entanglement generation between two quantum nodes situated 12.5 km apart, and the storage of entanglement exceeding the round-trip communication time. We also showed the concurrent entanglement generation on three links. Our work provides a metropolitan-scale testbed for the evaluation and exploration of multi-node quantum network protocols and starts a new stage of quantum internet research.