A team of researchers at the U.S. Department of Energy's Brookhaven National Laboratory and Stony Brook University has accomplished something no one else in the country has done: they beamed particles of light carrying quantum information across 13 miles of open atmosphere between two institutions on Long Island. The transmission, which took place on August 19 at 12:26 a.m. ET, represents the first permanent free-space optical quantum link in the United States. At a ceremony two days later, DOE Under Secretary for Science Darío Gil cut a ribbon on the receiving telescope as photons arrived in real time from Stony Brook's Quantum Watchtower. The daytime demonstration proved the system works even when background light levels are high. How It Works Conventional wireless technologies like cell phones and satellites rely on radio frequencies to send data without physical connections. But radio is far too noisy to preserve the fragile states required for quantum information. The Brookhaven and Stony Brook team turned instead to optical light, sending photons through the air the same way astronomers collect light from distant stars. From the rooftop of Stony Brook's Health Sciences Center, photons exited an optical fiber just five microns in diameter and traveled 21 kilometers to Brookhaven's Quantum Lighthouse, a facility perched atop a seven-story building. Adaptive optics expanded the beam to 25 inches to match the receiving telescope's mirror, then focused it back down to enter another five-micron fiber on the other side. Deformable mirrors running at kilohertz frequencies compensated for atmospheric turbulence in real time. "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. What Makes This Different The free-space optical link