The Bizarre Quantum Test That Could Keep Your Data Secure

At the Ludwig-Maximilian University of Munich, the basement of the physics building is connected to the economics building by nearly half a mile’s worth of optical fiber. It takes a photon three millionths of a second—and a physicist, about five minutes—to travel from one building to the other. Starting in November 2015, researchers beamed individual photons between the buildings, over and over again for seven months, for a physics experiment that could one day help secure your data.