Microwave multiphoton excitation of helium Rydberg atoms: The analogy with atomic collisions

W. van de Water; K. A. H. van Leeuwen; S. Yoakum; E. J. Galvez; L. Moorman; T. Bergeman; B. E. Sauer; P. M. Koch

doi:10.1103/PhysRevLett.63.762

Microwave multiphoton excitation of helium Rydberg atoms: The analogy with atomic collisions

W. van de Water, K. A. H. van Leeuwen, S. Yoakum, E. J. Galvez, L. Moorman, T. Bergeman, B. E. Sauer, and P. M. Koch

Phys. Rev. Lett. 63, 762 – Published 14 August 1989

Abstract

We study multiphoton transitions in helium Rydberg atoms subjected to a microwave electric field of fixed frequency but varying intensity. For each principal quantum number in the range n=25–32, the $n^{3}$ S to $n^{3}$ (L>2), n=25–32, transition probability exhibits very sharp structures as a function of the field amplitude. Their positions could be reproduced precisely using a Floquet Hamiltonian for the interaction between atom and field. Their shapes are determined by the transients of field turn-on and turn-off in a way that makes a close analogy with the theory of slow atomic collisions.