That may be set to change as astronomers turn to quantum physicists for help to start connecting optical telescopes that are tens, even hundreds, of kilometers away from one another. For example, the Center for High Angular Resolution Astronomy (CHARA) is an array of six one-meter optical telescopes operating at Mount Wilson Observatory in California, and it boasts a maximum baseline of 330 meters. The quantum states of the photons collected by each telescope—meaning the amplitude and phase of light as a function of time—are stored in quantum hard drives. Astronomers would physically transport these QHDs—by road, rail or air—to one location, where the quantum states would be read out and made to interfere, generating an interferogram. “It is a great idea to connect distant optical telescopes via QHDs,” Li says.