Lasers can trap light particles in clouds of atoms, which could be useful for future quantum computers Andrey Suslov/Alamy
Clouds of atoms can hide their light. When an atom moves to a lower-energy state, it emits a particle of light called a photon. But this process can be delayed and photons kept trapped inside a dense cloud of atoms, which may eventually prove useful for quantum devices that communicate using light.
When an atom absorbs a photon, exciting it to a higher-energy state, it will always release that photon and return to its initial state in approximately the same amount…
