Scientists Beamed Entangled Photons 13 Miles Through Open Air on Long Island
Researchers at the Department of Energy's Brookhaven National Laboratory and Stony Brook University sent pulses of light carrying quantum information 13 miles through open air between the two campuses, the laboratory said in a release issued jointly with Stony Brook on Aug. 21.
Each pulse held only a few photons, according to the release. They left the core of an optical fiber about 5 microns across at Stony Brook's Quantum Watchtower, a telescope facility on the roof of the university's Health Sciences Center, and crossed 13 miles, or 21 kilometers, to a matching rooftop facility at Brookhaven in Upton, New York, that the lab calls the Quantum Lighthouse.
Entangled photons came first. Brookhaven says its detectors at the Lighthouse registered them at 12:26 a.m. ET on Aug. 19, during nighttime tests when background light is lowest. Entangled pairs are particles whose measurements stay correlated no matter how far apart they travel, a property the release calls key to secure communication and to linking quantum computers. A daytime demonstration followed on Aug. 21.
The link adds a wireless leg to a fiber network that Brookhaven says spans 161 miles and eight nodes across Long Island and the New York metropolitan area. A third telescope facility at Yale University in New Haven, Connecticut, was recently completed, and the release says the next step is a 30-mile link across Long Island Sound.
"People think of telescopes as tools for looking up into space, but the same technologies that allow astronomers to precisely collect and control light are essential for these quantum experiments," said Justine Haupt, Brookhaven's lead scientist on the project.
The laboratory describes the transmission as "the first demonstration of its kind in the United States." Brookhaven's work is funded by the DOE Office of Science, and Stony Brook's by the National Science Foundation and Empire State Development, the release says.
