Time Dependent Perturbation Theory

Time dependent perturbation of a time-independent unperturbed Hamiltonian is treated by expanding perturbed state in unperturbed basic. Perturbation scheme for time-dependent expansion coefficients set up and solved in first order. Interaction picture provides another point of view. Two types of perturbation considered: perturbation independent of time, but acting for a specific interval and harmonic perturbation. Transition rate, energy conservation and time energy uncertainty relation are also discussed.