Klemens Hammerer

On an ordinary optical table, amid lasers and mirrors, a cloud of a hundred strontium-87 atoms begins to live by the laws of curved spacetime. Half a second later, its quantum interference fades: gravitational time dilation destroys the superposition.

A tiny crystal of charged atoms, trapped in a trap, trembles with heat. Each ion oscillates like a ball on a spring, and these vibrations hinder using the crystal for precise quantum operations. Usually, excess energy is removed with a laser — the beam hits the ions and slows their motion, like a stream of air damping a pendulum.

An orchestra without a conductor, where musicians hear each other through a shared wall. That's roughly how the new type of laser works: a few atoms (emitters) sit along a waveguide — a thin track for light on a chip. Light from each atom runs along this track and affects its neighbors.