Circular Rydberg-state spectroscopy

Abstract

We report the first observation of a resonance induced by a submillimeter wave between circular atomic Rydberg states of maximum angular momentum ($n=25$, ${m}_{l}=24\ensuremath{\rightarrow}n=24$, ${m}_{l}=23$ transition in lithium). This experiment is the first step towards a possible measurement of the Rydberg constant directly in frequency units. The Stark shift of the resonance has also been studied and its quadratic character put in evidence.