Jennifer T. Choy

A laser beam usually looks like a straight column of light. But if you pass it through a wafer with a pattern thinner than a hair, the beam scatters into thousands of tiny pockets of light. In each pocket, you can suspend a single atom, like a pea in a dimple.

Inside every rubidium-87 atom there is a tiny magnet — the nuclear spin and the electron spin. In a strong external field, these little magnets stop influencing each other and align independently, like two separate compasses.