title: Back and forth transfer and coherent coupling in a cold Rydberg dipole gas.
abstract: Coupling by the resonant dipole-dipole energy transfer between cold cesium Rydberg atoms is investigated using time-resolved narrow-band deexcitation spectroscopy. This technique combines the advantage of efficient Rydberg excitation with high-resolution spectroscopy at variable interaction times. Dipole-dipole interaction is observed spectroscopically as avoided level crossing. The coherent character of the process is linked to back and forth transfer in the np + np <--> ns + (n + 1)s reaction. Decoherence in the ensemble has two different origins: the atom motion induced by dipole-dipole interaction and the migration of the s-Rydberg excitation in the environment of p-Rydberg atoms.
authors.affiliation: Laboratoire Aimé Cotton, Campus d'Orsay Bât. 505, 91405 Orsay, France. mudrich@physik.uni-freiburg.de
authors.forename: Marcel
authors.initials: M
authors.lastname: Mudrich
authors.forename: Nassim
authors.initials: N
authors.lastname: Zahzam
authors.forename: Thibault
authors.initials: T
authors.lastname: Vogt
authors.forename: Daniel
authors.initials: D
authors.lastname: Comparat
authors.forename: Pierre
authors.initials: P
authors.lastname: Pillet