Pulse-driven quantum dynamics beyond the impulsive regime
  We review various unitary time-dependent perturbation theories and compare them formally and numerically. We show that the Kolmogorov-Arnold-Moser technique performs better owing to both the superexponential character of correction terms and the possibility to optimize the accuracy of a given level of approximation which is explored in details here. As an illustration, we consider a two-level system driven by short pulses beyond the sudden limit. 
D. Daems, S. Gu\'erin, H. R. Jauslin, A. Keller and O. Atabek