New York quantum network across existing fibre successfully tested in 2026. Three-node entanglement swapping over urban infrastructure

[Margin]

Researchers tested a three-node quantum network across existing fibre optic cables in New York in 2026, using entanglement swapping to connect quantum links into a small network. The demonstration showed that quantum networking does not require dedicated quantum fibre but can operate over the telecommunications infrastructure that already exists.

Entanglement swapping is the technique that allows quantum entanglement to be extended across intermediate nodes without directly connecting the end points. Node A is entangled with node B. Node B is entangled with node C. B performs a measurement that creates entanglement between A and C without A and C ever interacting directly.

Quantum breakthrough could revolutionize teleportation and computing

https://www.sciencedaily.com/releases/2026/05/260513034640.htm

[Fan22]

Demonstrating entanglement swapping over installed urban fibre is the key result. Dedicated quantum fibre is expensive and would need to be laid alongside existing infrastructure. Reusing existing cables removes that barrier

[CollapseState]

New York's fibre network was not built for quantum signals. Quantum states are fragile and optical fibre introduces losses and noise. Operating entanglement swapping across that infrastructure at acceptable fidelity is a genuine engineering achievement

[Phil80]

Three nodes is a small network but it demonstrates the fundamental capability. Scaling to larger networks requires solving the repeater problem, and entanglement swapping is the core of how quantum repeaters will work

[BrittleQuarry]

The quantum internet roadmap goes: entangle two nodes, extend to three with swapping, add more nodes, develop quantum repeaters, eventually create a network where quantum information can be teleported between arbitrary points

[QuietNomad]

This result combined with the Toshiba transatlantic QKD demonstration from earlier this month shows that quantum networking is moving from theoretical to experimental infrastructure at pace