Quantum networks leap from lab to live city fiber

By mid-2026, Northwestern University’s Kumar Lab achieved a landmark demonstration of atom–photon quantum entanglement transmitted over 24.4 kilometers of live urban commercial fiber in Chicago, maintaining over 94% entanglement fidelity despite the fiber carrying 1.6 terabits per second of classical internet traffic. This feat was enabled by innovative use of custom-built quantum-frequency converters to shift photons into the O-band, isolating them from conventional C-band data, and employing advanced filtering alongside picosecond-level synchronization via the White Rabbit optical timing system. These engineering breakthroughs addressed longstanding noise challenges such as spontaneous Raman scattering and four-wave mixing, effectively closing a 12-year gap between theoretical noise barriers and practical quantum signal survival in real-world metropolitan fiber networks.

Earlier in 2025, NIST researchers demonstrated the transmission of entangled photons over a notably longer 62-kilometer commercial fiber link between Gaithersburg and College Park, achieving a 92.8% success rate despite the fiber’s exposure to harsh environmental conditions described by physicist Yicheng Shi as 'about as bad a connection as you can possibly have.' This practical stress test was made possible by a real-time polarization stabilization system developed by Qunnect, which actively corrected fiber-induced distortions to preserve entanglement and maintained a distribution rate of 1,500 entangled photons per second. NIST’s achievement underscored the feasibility of integrating quantum communication protocols with existing telecommunication infrastructure outside controlled laboratory settings, marking a significant step toward practical quantum networks.

In July 2026, Cisco, Aliro Technologies, and zerothird achieved a landmark demonstration by integrating entanglement-based quantum key distribution (eQKD) with Cisco’s 8000-Series routers, utilizing zerothird’s BBM92 protocol hardware and Aliro’s Orchestrator software. This collaboration not only showcased operational readiness but also proved multi-vendor interoperability, a critical milestone for advancing quantum-safe networking within enterprise IT environments. The system’s ability to deliver quantum-derived keys directly to routers via the Secure Key Integration Protocol (SKIP) enabled live quantum-secure MACsec-encrypted sessions on production-grade infrastructure, underscoring practical deployment viability.

Beyond mere integration, the joint system incorporated sophisticated automated security operations, including real-time telemetry, eavesdropper detection, and dynamic remediation workflows such as recalibration or traffic rerouting when security thresholds were breached. Managed by Aliro’s Orchestrator, continuous monitoring of critical metrics like quantum bit error rate exemplifies a full-stack approach that tightly couples hardware and software to maintain quantum-safe security. Executives emphasized that this comprehensive orchestration is essential for operational resilience and highlights the practical readiness of quantum networks for enterprise deployment.

This milestone also underscores the strategic importance of multi-vendor compatibility for scalable quantum networking. By successfully demonstrating seamless interoperability among zerothird’s quantum key generation hardware, Aliro’s orchestration platform, and Cisco’s routing infrastructure, the collaboration sets a precedent for future quantum network deployments that require diverse ecosystem players to work in concert. As industry leaders note, the path to widespread quantum-safe security depends on such full-stack, multi-vendor integration to ensure flexibility, scalability, and robustness in real-world enterprise environments.

By mid-2026, Qunnect pioneered the U.S. quantum networking landscape with the launch of ABQ-Net in Albuquerque, New Mexico, the nation’s first open-access entanglement-based quantum network testbed. This initiative, underpinned by New Mexico’s ambitious $300 million investment to foster a regional quantum commercialization ecosystem, offers affordable, live quantum network access over commercial telecom fibers and leverages Qunnect’s Carina entanglement distribution system operating at room temperature to accelerate advancements in quantum cybersecurity, distributed quantum processing, and sensing.

Just over a month later, ABQ-Net rapidly expanded its strategic footprint by partnering with four leading quantum technology companies—Infleqtion, Aliro Technologies, Tensora, and Bandelier Technologies—to develop and validate cutting-edge defense, security, and geosensing applications on live metropolitan fiber. This collaboration is a cornerstone of New Mexico’s broader $450 million quantum commercialization initiative, positioning ABQ-Net as a critical open-access testbed that empowers startups and innovators to trial quantum hardware and software without the prohibitive costs of building their own infrastructure.

The initial ABQ-Net deployment strategically connects Qunnect’s Albuquerque office with the Department of Energy’s Center for Integrated Nanotechnologies, establishing a practical quantum network backbone that is set to grow by linking additional research and defense institutions such as the Air Force Research Laboratory and the University of New Mexico. This expansion signals a significant evolution from isolated quantum experiments toward robust, metropolitan-scale quantum network deployments with real-world applications in defense and geosensing.

In a landmark advancement for quantum networking, IonQ has successfully embedded the world's first commercial quantum memory unit within a live fiber-optic network, a milestone realized through the Tennessee Quantum Communications Research Center—a $15 million, five-year collaboration with EPB. This deployment signifies a pivotal transition of quantum memory technology from controlled laboratory settings into the complex, real-world environment of existing fiber infrastructure, where it must coexist with conventional internet traffic and withstand environmental interference. By integrating quantum memory directly into the same fiber that serves a mid-sized American city, IonQ addresses critical practical challenges, laying the groundwork for scalable quantum repeaters essential for extending quantum communication beyond the 100 km transmission barrier.

Quantum memory's role is indispensable in overcoming the inherent limitations of fiber-based quantum communication, as it enables the storage and synchronization of entangled quantum states across network nodes—functionality vital for constructing quantum repeaters. Without this capability, nodes cannot maintain their share of entanglement long enough to coordinate with adjacent links, rendering practical quantum repeaters unattainable. IonQ's commercial quantum memory unit thus represents a foundational component in the quest to build robust, long-distance quantum networks, marking a significant stride toward realizing the full potential of quantum internet infrastructure.

In a groundbreaking demonstration completed in early 2025, NIST, UMD, and Qunnect showcased real-time polarization stabilization over 62 kilometers of aerial commercial fiber, a notoriously challenging medium due to environmental disturbances like wind and temperature fluctuations. Leveraging Qunnect's automated polarization compensation (APC) devices, which continuously measure and invert time-varying birefringence effects, the team preserved quantum entanglement by actively correcting polarization distortions, effectively maintaining the fragile quantum link despite the fiber's exposure to real-world noise.

The robustness of this system was emphatically proven during a continuous 24-hour stress test, where the quantum network achieved a remarkable 92.8% uptime and maintained a sustained violation of the classical Bell inequality, with a time-averaged CHSH parameter of S=2.45±0.08 over 20 hours. NIST physicist Yicheng Shi described the experiment as 'a stress test of quantum networking systems' in an environment 'really noisy,' highlighting that entanglement distribution succeeded with polarization corrections needed only 7.2% of the time, thereby confirming the practical viability and operational resilience of quantum networks in metropolitan aerial fiber deployments.