EN
The interaction of multi-level atoms with several to many lasers simultaneously is examined in two regimes, the "short" regime of resonant atomic response to prescribed laser fields, and the "long" regime of resonant pulse propagation in which several to many laser pulses pass through an active medium composed of many-level atoms. Results obtained with I. Białynicki-Birula et al. in the short regime are reviewed, and new results in the long regime are described.