Magneto-optical trap

A magneto-optical trap uses red-detuned laser beams and a spatially varying magnetic field to cool and confine neutral atoms near a central point.

Doppler cooling: Laser cooling that reduces atomic motion by making atoms absorb more light when moving toward a red-detuned beam. Counter-propagating beams use Doppler shifts to slow atoms in the trap.
Laser cooling: Techniques that reduce the motion of atoms or molecules through interactions with light. A magneto-optical trap combines laser cooling with spatial confinement.
Cold-atom physics: The study of atoms cooled to temperatures where their motion and quantum properties can be precisely controlled. Magneto-optical traps are a standard source of cold atoms for this field.
Magnetic trap: A device that confines particles with magnetic moments using a spatially varying magnetic field. It confines suitable atoms without the near-resonant cooling beams used by this trap.
Zeeman effect: The splitting or shifting of atomic energy levels in a magnetic field. The field gradient shifts atomic transitions with position, selecting the restoring beam.
Atomic transition: A change between quantized energy states of an atom, often accompanied by absorption or emission of a photon. The laser frequency is tuned near a transition that cycles atoms through photon scattering.
Optical dipole trap: A trap that confines neutral particles through the conservative force of an intensity-dependent light shift. Atoms are often transferred from a magneto-optical trap into this field-free confinement stage.
Zeeman slower: A device that slows an atomic beam using radiation pressure while a magnetic field compensates for changing Doppler shifts. It slows atoms in a beam rather than cooling and confining them at a point.
Optical pumping: The redistribution of atomic populations among internal states through absorption and emission of light. Circularly polarized beams optically pump atoms into states that experience position-dependent forces.
Natural linewidth: The frequency width of an atomic transition caused by the finite lifetime of its excited state. The transition linewidth sets a characteristic scale for laser detuning and attainable cooling.

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