Rydberg-Rydberg interaction in the second-harmonic generation from rubidium atoms

Abstract

We report on the observation of long range interaction in the second-harmonic generation from rubidium Rydberg atoms. The asymmetric spectral broadening of the resonant lines provides evidence of the van der Waals interaction between pairs of Rydberg atoms. This effect is investigated when the two-photon transition is resonant with $nd$ levels for $n\ensuremath{\approx}13$.