Northwestern Sends Entangled Photons 24.4 Kilometers Over Live Fiber at 94.2% Fidelity
Updated
Updated · Tech Times · Jul 26
Northwestern Sends Entangled Photons 24.4 Kilometers Over Live Fiber at 94.2% Fidelity
1 articles · Updated · Tech Times · Jul 26
Summary
Northwestern researchers distributed entangled photons across a 24.4-kilometer commercial fiber link between Evanston and downtown Chicago while the same cable carried 1.6 terabits per second of live internet traffic.
A 94.2% Bell-state fidelity matched the team's dark-fiber result, showing commercial traffic caused essentially no measurable degradation and clearing the classical threshold for genuine entanglement by a wide margin.
The setup worked by separating quantum signals into the O-band around 1,290-1,310 nanometers, filtering residual Raman noise, and using White Rabbit timing to synchronize remote detectors with about 4.6-picosecond jitter.
The test ran on a deployed Ciena optical system at production-like power, making it the first entanglement distribution between independently synchronized remote nodes on the same live fiber as modern telecom traffic.
The result could remove the need for costly dedicated dark fiber for metro-scale quantum networks, though full quantum teleportation over live commercial links remains the team's next target.
If heavy internet traffic cannot destroy fragile quantum signals, what are the actual limits of our fiber infrastructure?
Will upgrading existing telecom nodes for quantum signals truly cost less than laying entirely new dark fiber networks?
Could the secret to a global quantum internet already be buried beneath our city streets?
36-Tbps Classical Data and Quantum Entanglement Coexist: Northwestern’s 2026 Leap Toward the Quantum Internet
Overview
In July 2026, Northwestern University researchers achieved a major breakthrough by proving that delicate quantum signals can coexist with powerful classical internet traffic in the same fiber-optic cable. By shifting quantum photons to a quieter part of the spectrum and using advanced synchronization and filtering, they overcame noise and timing challenges. This means existing fiber networks can support quantum networking without costly new infrastructure, accelerating global deployment. However, scaling up requires new hardware like quantum repeaters and switches, as well as robust security and regulatory measures, especially with the looming threat of quantum computers breaking current encryption. This work marks a crucial step toward a practical, secure quantum internet.