Time-dependent perturbation theory
Time-dependent perturbation theory is one of the most useful techniques for understanding how quantum mechanical systems respond in time to changes in their environment. It is especially useful for understanding the consequences of periodic changes; a classic example is understanding how a quantum mechanical system responds to light, which can often be usefully approximated as a periodically oscillating electromagnetic field. We develop time-dependent perturbation theory in this chapter, including some specific applications to interactions with light.
7.1 Time-dependent perturbations
For time-dependent problems, we are often interested in the situation where we have some ...