Time dependence of a two-level system for arbitrary sinusoidal field strengths and times

Abstract
An exact formal and practical solution for the time-dependent Schrödinger equation is given for a two-level system in an arbitrarily strong sinusoidal field. The periodicity of the time-dependent wave equation is fully exploited and the solution over the initial period of the wave equation essentially provides the complete solution for arbitrarily long times. The solution over the initial time period is generated by using a previously derived power series technique. The method is illustrated by explicit examples.