A team from Brookhaven National Laboratory and Stony Brook University has demonstrated a 21-kilometer (13-mile) free-space quantum link. They successfully transmitted both single photons and entangled photon pairs through the atmosphere, connecting the «Quantum Watchtower» at Stony Brook to the «Quantum Lighthouse» at Brookhaven. This marks the first U.S. demonstration of such a wireless segment within a functioning quantum network. The key advantage: the system uses infrared wavelengths that are naturally compatible with certain quantum processors and atomic systems — unlike fiber-optic networks, which are limited to telecom bands. The new link will be integrated into an existing fiber-based quantum network across Long Island, enabling hybrid fiber-free-space networking. Plans include extending the network further — with a 48-kilometer free-space connection planned between Stony Brook and Yale University across Long Island Sound.
About the Author
