The matrix elements of the timehyphen;development operator are obtained exactly for the influence of many resonant or nearhyphen;resonant fields on a system with a finite number of levels for arbitrary initial conditions in a wide class of problems. Perturbative techniques are presented which enable the exact treatment of all perturbations to a desired order. As examples, a threehyphen;level doublehyphen;resonance and two eighthyphen;level triplehyphen;resonance systems are given. The applications of these exact solutions to the treatment of perturbations, including relaxation phenomena, are presented using both standardhyphen;perturbationhyphen;theory and densityhyphen;matrix techniques.
展开▼
