Brookhaven National Laboratory and Stony Brook University reported a 13-mile (21-kilometer) free-space optical quantum link on August 21, 2026. The connection sends quantum states through open air between Stony Brook's Quantum Watchtower and Brookhaven's Quantum Lighthouse in Upton, New York.
The result adds an atmospheric link to an existing fiber network spanning 161 miles across Long Island and the New York metropolitan area. The institutions describe the demonstration as the first permanent free-space optical quantum link of its kind in the United States.
The link carries quantum states through open air
During a daytime demonstration, researchers generated quantum states containing only a few photons at Stony Brook. The signal left an optical fiber with a core about five microns wide, crossed 13 miles of atmosphere, and entered Brookhaven's receiving telescope.
Nighttime tests went further. Researchers sent entangled photons from Stony Brook's physics laboratory through the Watchtower and across the free-space link. Brookhaven's Quantum Lighthouse detected and measured the photons.
The Stony Brook announcement attributes the result to a system combining photon sources, detectors, controls, communications, and adaptive optics. The Brookhaven facility description explains how the telescope expands a tiny beam to roughly 0.6 meters before focusing the signal back into a fiber at the receiving end.
Why free space matters for quantum networks
Fiber remains useful for long-distance quantum links, but fiber infrastructure fixes each route and favors telecom wavelengths. Free-space optical links add line-of-sight routes between rooftops, research sites, and future ground stations.
The Brookhaven and Stony Brook system also explores wavelengths closer to those used by quantum processors and related devices. The team says this path supports direct connections between different types of quantum hardware without requiring every link to use commercial telecom fiber.
The distinction matters for distributed quantum computing. A cloud API sends classical instructions to a remote QPU. A distributed quantum computer needs a physical channel for quantum states or entanglement. This experiment addresses the channel, not the full distributed-computing problem.
The next link crosses Long Island Sound
A third free-space facility is under development at Yale University in New Haven, Connecticut. The researchers plan to establish a 30-mile (48-kilometer) connection between Stony Brook and Yale across Long Island Sound.
The wider plan also includes quantum links to satellites. Satellite connections would extend quantum communication beyond regional fiber and line-of-sight testbeds, although atmospheric loss, alignment, weather, and quantum memory requirements still need engineering work.
The current result proves operation of a long free-space quantum link and detection of entangled photons. A quantum repeater, long-lived memory, and distributed computation require further demonstrations. Those next steps will show whether free-space links move from a research network component into a dependable part of larger quantum systems.