Cisco and Qunnect build quantum network using New York fiber optic cables

The experiment solves key challenges in building quantum networks in existing data centers and cities.

Published on Feb. 21, 2026

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Cisco Systems and startup Qunnect have built and operated a quantum network between Brooklyn and Manhattan in New York, which sends signals over real-world fiber optic cables and works as well as studies in labs. The experiment, using Qunnect's hardware and Cisco's software, solved some key challenges in building such networks in existing data centers and cities.

Why it matters

Quantum computers and networks are normally sensitive to the slightest vibration, but Qunnect's technology - specifically devices called automatic polarization controllers - keeps the quantum network intact over a 17.6 kilometer stretch of fiber optic cable, correcting for real-world problems in data centers. This is a foundational step towards Cisco's goal of connecting quantum computers together inside a data center and then connecting those quantum data centers into a quantum internet.

The details

The experiment used Brooklyn-based Qunnect's hardware and Cisco's software. Qunnect's approach requires cryogenic cooling only at one central hub, while other data centers connected to the hub can use room-temperature equipment. The research paper said Qunnect's technology keeps the quantum network intact over the 17.6 kilometer fiber optic cable, correcting for issues like different patch panels that make the fiber optic infrastructure look like a 'rat's nest'.

  • The experiment was conducted and announced on February 18, 2026.

The players

Cisco Systems

A multinational technology conglomerate that develops, manufactures, and sells networking hardware, telecommunications equipment, and other high-technology services and products.

Qunnect

A Brooklyn-based startup that develops hardware and software for building quantum networks.

Noel Goddard

The CEO of Qunnect.

Ramana Kompella

The vice president and head of Cisco Research.

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What they’re saying

“It corrects for real-world problems, data centers have these tens of kilometers of fiber, and they run through all sorts of different patch panels, all of the things that make it look like a rat's nest.”

— Noel Goddard, CEO, Qunnect

“Trading computers that are tens of kilometers away, and they want to make a coordinated decision or a stock sell or a buy, without hitting the speed of light limitations you typically have. Quantum entanglement networks can actually really help.”

— Ramana Kompella, Vice President and Head of Cisco Research

What’s next

Cisco and Qunnect plan to continue developing and expanding their quantum network technology, with the goal of eventually connecting quantum computers together inside data centers and then connecting those quantum data centers into a quantum internet.

The takeaway

This experiment represents a significant step forward in the development of practical quantum networks, overcoming key challenges around vibration sensitivity and real-world infrastructure. The ability to build quantum networks using existing fiber optic cables brings quantum computing and communication one step closer to mainstream adoption.