Measuring the van der Waals forces between a Rydberg atom and a metallic surface.

Abstract

We have observed the deflection of Rydberg atoms towards a metallic surface by the van der Waals force. Cs and Na atoms in states of principal quantum number n were sent between two parallel gold-coated mirrors, spaced by a gap w (2.1 \ensuremath{\mu}m\ensuremath{\le}w\ensuremath{\le}8.5 \ensuremath{\mu}m). We measured the value ${n}_{m}$ at which the transmission cuts off and from the variation of ${n}_{m}$ versus w, we obtained a measure of the atom-surface interaction. For $12<n<30$ this interaction is 3--4 orders of magnitude larger than for ground-state atoms, and it obeys the scaling laws of the Lennard-Jones model.