The birth of quantum networks: merging remote entanglement with local multi-qubit control

Farhan Saif, Sami Ul Haq

Ronald Hanson

We report on the realization of a three-node entanglement-based quantum network. We combine remote quantum nodes based on diamond communication qubits into a scalable phase-stabilized architecture, supplemented with a robust memory qubit and local quantum logic. Also, we achieve real-time communication and feed-forward gate operations across the network. We demonstrate two key quantum network protocols without post-selection: the distribution of genuine multipartite entangled states across the three nodes and entanglement swapping through an intermediary node. Finally, we will discuss the most recent experiments using the network as a platform for exploring, testing, and developing multi-node quantum network protocols and a quantum network control stack.

H. J. Briegel, S. J. van Enk, J. I. Cirac +9 more

Wanbin Zhang, Baosheng Li, Zhanjun Zhang

Abstract In a local quantum network, multi-qubits in various entangled states might be distributed in different remote nodes due to some peculiar demands. In this paper we consider a seven-qubit entangled state in a given qubit distribution among three participants and study its capacity in quantum teleportation (QT). To be specific, we put forward three controlled QT schemes utilizing the state. In each scheme QT can be deterministically and bidirectionally realized between two participants with another as the controller.

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Mariagrazia Iuliano, Nicolas Demetriou, H. Benjamin van Ommen +3 more

Quantum networks connecting quantum processing nodes via photonic links enable distributed and modular quantum computation. In this framework, quantum gates between remote qubits can be realized using quantum teleportation protocols. The essential requirements for such non-local gates are remote entanglement, local quantum logic within each processor, and classical communication between nodes to perform operations based on measurement outcomes. Here, we demonstrate an unconditional Controlled-NOT quantum gate between remote diamond-based qubit devices. The control and target qubits are Carbon-13 nuclear spins, while NV electron spins enable local logic, readout, and remote entanglement generation. We benchmark the system by creating a Greenberger-Horne-Zeilinger state, showing genuine 4-partite entanglement shared between nodes. Using deterministic logic, single-shot readout, and real-time feed-forward, we implement non-local gates without post-selection. These results demonstrate a key capability for solid-state quantum networks, enabling exploration of distributed quantum computing and testing of complex network protocols on fully integrated systems.