Laser cooling as a form of optical pumping in the quantum domain of atomic motion

Laser cooling has advanced to the point where atomic motion can no longer be described in terms of discrete particles moving on classical trajectories. Instead, de Broglie wave fields occupy quantum states of a potential created by the interaction between atoms and the light field. Atomic transitions between these quantum states are mediated by optical pumping, in much the same way as transitions were made between internal angular momentum states in Prof. Series' time. Some examples are studied here, with special emphasis on dark states.