Cisco and Qunnect Demonstrate First Metro-Scale Quantum Entanglement Network Across New York City
Cisco and Qunnect achieved first metro-scale quantum entanglement swapping over 17.6 km of commercial NYC fiber, surpassing previous benchmarks by 10,000x.
Overview
Researchers from Qunnect and Cisco have demonstrated the first metro-scale, high-speed quantum entanglement swapping over deployed commercial fiber, connecting Brooklyn and Manhattan across 17.6 kilometers of live telecommunications infrastructure in New York City. Announced on February 18, 2026, the milestone marks a significant step toward practical quantum networking and distributed quantum computing beyond laboratory settings.
What Was Demonstrated
The experiment took place on Qunnect’s GothamQ testbed, using QTD Systems’ data center at 60 Hudson Street in Manhattan as the central hub. According to Qunnect’s announcement, two independent entanglement sources located in Brooklyn connected via standard deployed fiber to the Manhattan hub, where entanglement swapping — the process of linking two pairs of entangled photons to extend a quantum connection across a longer distance — was performed.
The system achieved swapping rates of 1.7 million entangled photon pairs per hour under local conditions and 5,400 pairs per hour over the full 17.6-kilometer deployed network, representing a nearly 10,000-fold improvement over previous benchmarks using similar platforms. Polarization fidelity was maintained above 99% throughout, a critical requirement for reliable quantum communications across noisy urban fiber.
Technical Innovations
Several design choices distinguish this deployment from previous experiments. Qunnect’s Carina system, the entanglement source used in the demonstration, operates at room temperature rather than requiring the deep cryogenic cooling typical of many quantum systems. As reported by Quantum Zeitgeist, this significantly reduces infrastructure complexity and cost at remote network endpoints, concentrating the more expensive cryogenic hardware — single-photon detectors known as SNSPDs — only at the central hub.
The architecture also eliminates a longstanding requirement in quantum networks: independent atomic sources at each node no longer need to share a master laser for synchronization. This decoupled approach underpins a hub-and-spoke topology that can scale using commercial data centers as network anchors, without redesigning the fiber infrastructure that already exists in cities.
Cisco contributed a unified quantum networking software stack that coordinated calibration, timing, and data correlation across the nodes. Reza Nejabati, Cisco’s Head of Quantum Research, described the software as functioning like a “digital air traffic controller,” managing operations across distributed quantum hardware in real time, according to Quantum Computing Report.
Significance and Context
Entanglement swapping is considered a foundational capability for building a quantum internet — a network that distributes quantum states between distant nodes to enable applications including quantum-secure communications and distributed quantum computing. Mehdi Namazi, Qunnect’s Co-Founder and Chief Science Officer, noted that the demonstration was conducted in “some of the noisiest, most chaotic fiber on Earth,” arguing that real-world urban conditions provide a more meaningful test than controlled laboratory environments.
Qunnect, a Brooklyn-based company founded in 2021 to commercialize room-temperature quantum networking hardware, operates live quantum testbeds in both New York and Berlin. According to the company, results from the GothamQ demonstration have been published on arXiv as a deployable blueprint for other metropolitan quantum networks.
What Remains to Be Done
Despite the record performance, the demonstration highlights how much work lies ahead before quantum networks become practical infrastructure. Quantum Computing Report notes that quantum memory — which would allow entangled states to be stored and retrieved rather than simply relayed — remains under development and represents a critical missing piece for extending quantum networks across continental or intercontinental distances. Without quantum memory, current entanglement swapping systems can link nodes but cannot yet build the repeater chains needed to span thousands of kilometers.
Cost, standardization, and integration with existing classical network equipment are additional challenges that must be addressed before enterprises could begin deploying quantum networking alongside conventional infrastructure. Nevertheless, Cisco characterized the milestone as accelerating its quantum networking roadmap toward what Nejabati described as “distributed quantum computing and the global quantum grid.”