# Laboratoire Collisions Agrégats Réactivité - UMR5589

Université Paul Sabatier - Bat. 3R1b4 - 118 route de Narbonne 31062 Toulouse Cedex 09, France

## Chirping a two-photon transition in a multi-state ladder

We consider a two-photon transition in a specific ladder system driven by a chirped laser pulse. In the weak field limit, we find that the excited state probability amplitude arises due to interference of multiple quantum paths which are weighted by quadratic phase factors. The excited state population has the form of a Gauss sum which plays a prominent role in number theory.

Voir en ligne : Phys. Rev. A 76, 023417/1-10 (2007)