Cisco and Qunnect test real-world quantum network over New York fiber cables

Summary

• Cisco and Qunnect demonstrated a metro-scale quantum network using existing New York fiber.
• The trial linked Brooklyn to a Manhattan data center over ~17.6 km of telecom infrastructure.
• Results show quantum signals can operate outside lab conditions, advancing prospects for a future quantum internet.

BROOKLYN, N.Y., Feb. 18, 2026 — Cisco Systems and quantum networking startup Qunnect have successfully demonstrated a high-speed quantum networking trial over existing fiber-optic cables in New York City, marking a step toward practical large-scale quantum communications.

The test showed that quantum signals can be transmitted reliably across real-world telecom infrastructure — a significant milestone beyond laboratory-only demonstrations.

Bringing quantum networking into the real world

The experiment used Qunnect’s GothamQ network, spanning roughly 17.6 kilometers (about 11 miles) of deployed fiber connecting Brooklyn with a major data-center hub at 60 Hudson Street in Manhattan.

Unlike earlier quantum networking experiments that relied heavily on specialized environments, the setup adopted a more practical architecture:

• Centralized cryogenic systems at a hub to manage cooling requirements
• Room-temperature hardware at endpoints, allowing integration with conventional data-center equipment

This approach suggests quantum networking could eventually be layered onto existing telecom infrastructure.

Demonstrating entanglement distribution at scale

A key achievement of the trial was demonstrating entanglement swapping, a core mechanism required for long-distance quantum communication.

According to the companies:

• Swapping rates reached about 1.7 million pairs per hour in local testing
• Roughly 5,400 pairs per hour were achieved across the deployed urban fiber
• Signal fidelity exceeded 99%, indicating stable performance

The results represent a significant improvement compared with earlier metro-scale experiments, though further testing will be needed to validate scalability.

Overcoming urban network challenges

Quantum signals are highly sensitive to environmental disturbances.
In dense urban infrastructure, vibrations, temperature fluctuations, and complex routing can disrupt polarization.

The trial used automatic polarization control systems to maintain stability, demonstrating that quantum links can operate through typical telecom equipment such as patch panels and city fiber routes.

Why this matters

The demonstration suggests quantum networking is moving from theoretical research toward practical deployment.

If scaled, metro-level quantum networks could enable:

• Ultra-secure communications using quantum encryption
• Precise time synchronization for financial and telecom systems
• Distributed quantum computing architectures

While a global quantum internet remains years away, real-world trials like this indicate the technology is entering an early commercialization phase.

FAQs

Q1. What is entanglement swapping?

A technique that links two independent quantum particles, enabling long-distance quantum communication.

Q2. Did the trial require new fiber infrastructure?

No — it used existing telecom fiber, showing compatibility with current networks.

Q3. Is the quantum internet available today?

Not yet. The technology is still in early development, but metro-scale deployments could emerge over the next decade.