A FIELD-MOMENTUM APPROACH TO THE SEMICLASSICAL THEORY OF LIGHT FORCESON ATOMS

The semiclassical light force on a free atom is derived as the reactio n on the atom of momentum loss from and exchange between plane wave mo des of a classical light field. This approach leads directly to an exp ression for the force that is computationally convenient for multidime nsional laser field configurations under conditions where a two-level model of the atoms is appropriate, and provides insight into the origi n of the light force in terms of loss, gain and exchange of mode momen ta.