US quantum communication breakthroughs

In late July 2026 researchers at Northwestern University first demonstrated that entangled photon pairs could be transmitted over a 24.4‑kilometre commercial fiber‑optic link in Chicago while the same cable carried high‑capacity internet traffic, preserving more than 94 % entanglement fidelity. This experiment showed that delicate quantum signals can coexist with existing telecom infrastructure, a key step toward practical metropolitan quantum networks.

A week later, additional work expanded the scope of quantum communications. A deep‑learning adaptive‑optics system was used to correct atmospheric turbulence, enabling free‑space quantum key distribution (QKD) over 1.4 km and 7 km links even in daylight—overcoming the long‑standing limitation of night‑only QKD. The same study reiterated the Northwestern fiber‑entanglement result, underscoring that both free‑space and fiber‑based quantum links can operate alongside conventional data traffic. Together, these advances point toward all‑day, hybrid quantum communication networks that could form the backbone of future global quantum infrastructure.