Which technique earned Steven Chu, Claude Cohen-Tannoudji and William D. Phillips the 1997 Nobel Prize in Physics?

Laser cooling and trapping atoms earned Steven Chu, Claude Cohen-Tannoudji and William D. Phillips the 1997 Nobel Prize in Physics.

Their work showed how carefully tuned laser light can slow atoms and hold them in place. When an atom moves toward opposing laser beams, it encounters light shifted closer to resonance, increasing photon absorption against its motion. Repeated absorption and re-emission transfers momentum and reduces the atom’s speed, lowering its temperature.

The researchers also developed methods for trapping and studying ultracold atoms. Such systems allow exceptionally precise measurements of atomic properties and provide controlled settings for testing fundamental physics. Laser cooling became important in atomic clocks, quantum experiments and technologies based on cold atoms.

This method does not cool atoms by simply removing heat with a conventional refrigerator. It changes atomic motion through photon momentum and carefully arranged light fields. The Nobel citation referred to development of methods to cool and trap atoms with laser light.