Philip Walther

For the first time in a lab, researchers directly measured how gravity alters the path of single photons. They built a tabletop labyrinth from 50 km of fiber. The device compared the paths of two halves of a photon wave and detected a delay of millionths of a radian—a result of spacetime curvature.

Two artificial atoms linked by a waveguide made photons bunch into triplets. This is a step toward creating quantum simulators and studying exotic states of matter.