Scattering of two-level atoms by delta lasers: Exactly solvable models   in atom optics
  We study the scattering of two-level atoms at narrow laser fields, modeled by a $\delta$-shape intensity profile. The unique properties of these potentials allow us to give simple analytic solutions for one or two field zones. Several applications are studied: a single $\delta$-laser may serve as a detector model for atom detection and arrival-time measurements, either by means of fluorescence or variations in occupation probabilities. We show that, in principle, this ideal detector can measure the particle density, the quantum mechanical flux, arrival time distributions or local kinetic energy densities. Moreover, two spatially separated $\delta$-lasers are used to investigate quantized-motion effects on Ramsey interferometry. 
D. Seidel, J.G. Muga, G.C. Hegerfeldt