Atomic motion in resonant radiation: An application of Ehrenfest's theorem

A new theory of atomic motion in a resonant or near-resonant electromagnetic wave, based on Ehrenfest's theorem and the optical Bloch equations, is presented. The theory provides a simple unified treatment of the radiation force, including effects of spontaneous emission and induced-dipole interactions. Analytical results are presented for a plane running wave, a general standing wave, a collimated Gaussian beam, and a combination of standing and running waves.