New free-space optical link adds a wireless component to the nation's longest quantum network

There's a new lighthouse on Long Island. But instead of shining light to guide ships through waterways, this one transmits and receives particles of light that carry quantum information. Perched atop a seven-story building at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory, the "Quantum Lighthouse" is a key pillar of the free-space optical (FSO) link spanning Brookhaven Lab, the State University of New York at Stony Brook (Stony Brook University) and Yale University.