In early 2025, special signals wended their way through a fiber-optic highway strung above the streets and sidewalks of the Maryland suburbs. The arrival of those signals at their destination marks a significant step toward a long-held dream of building a “quantum network.” Researchers believe that this emerging technology could someday link quantum devices in ways that supercharge scientific research, enable ultrasecure communications and boost the power of future quantum computers. National Institute of Standards and Technology (NIST) researchers and collaborators reported this advance in the Journal of Optical Communications and Networking. Quantum networks depend on a special phenomenon called entanglement. Often described as “spooky action at a distance” (a translation of a phrase coined by Albert Einstein), entangled objects share a unified quantum state, meaning they cannot be described independently even if they are far apart. When one object from an entangled pair is measured, this action determines the results of a measurement made on the other. These long-distance links could reshape fields from astronomy to seismology to drug discovery. By sharing entangled photons, telescopes thousands of kilometers apart could someday collect and combine light from the same distant star or planet, yielding a much sharper image than any one telescope could on its own. Entangled sensors spread over an area could “listen” for tiny seismic disturbances and pinpoint a coming earthquake or volcanic eruption. Networks of entangled quantum computers, meanwhile, might someday crunch algorithms too complex for any single device, helping scientists simulate potential new drugs and materials. Another possible application: ultrasecure communications networks where any attempt at hacking would be easily detected. To unlock such benefits, however, scientists must first overcome multiple technical challenges. Among the biggest hurdles is finding a way to keep fragile entangled states alive outside the lab. Quantum networks gain their power by