= Cold atom
A <cold atom> has a small motional <kinetic energy> relative to a stated experimental scale. Usually an ensemble is prepared with a narrow <velocity> distribution through <laser cooling> or <evaporative cooling of atoms>; the quoted <temperature> characterizes motion rather than requiring the atom's internal electronic state to be thermally equilibrated.
Slower motion increases the time available for interrogation in <atomic clocks> or <atom interferometry>. In a release experiment, a cloud's growth after the trap is switched off constrains its <velocity> spread. Distinguishing initial cloud size from expansion avoids mistaking tight confinement for low motional <temperature>.
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