Laser cooling uses laser light to reduce the random velocities of chemical atoms, and therefore their translational temperature. The striking ingredient is selective photon absorption: an atom moving towards a beam sees a Doppler shift that can make it absorb more strongly. Each absorbed photon transfers momentum along the beam; repeated absorption and spontaneous emission can then remove kinetic energy. Doppler cooling makes this selection with the atom's motion, while sub-Doppler cooling also exploits its internal quantum states.
Cooling makes chemical atoms move slowly enough for longer interrogation in atomic clocks and atom interferometry, and easier loading into an optical trap. The same radiation pressure that pushes an atom can cool it: with suitably tuned opposing beams, whichever direction the atom moves, it receives the stronger push against that motion.
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Laser cooling is a technique used to reduce the kinetic energy of atoms or particles, effectively lowering their temperature. This process utilizes the interaction between laser light and the atoms to slow them down, which causes a decrease in their thermal motion. The basic principle of laser cooling involves using a laser beam tuned slightly below an atomic transition frequency. When an atom absorbs a photon from the laser, it gains momentum in the direction of the incoming photon.
