Observation of intrastate and interstate facilitation between Rydberg S, P and D levels

TL;DR

This paper experimentally demonstrates Rydberg facilitation in rubidium across S, P, and D levels, showing enhanced excitation and correlations due to Rydberg-Rydberg interactions, and explores inter-state facilitation effects.

Contribution

It provides the first detailed experimental observation of facilitation across multiple Rydberg levels and between different Rydberg states, supported by theoretical potential calculations.

Findings

Facilitation observed for both blue and red detuning in S, P, and D Rydberg states.

Correlation measurements show super-Poissonian statistics during facilitation.

Inter-state facilitation between 70 S and 70 P Rydberg levels confirmed.

Abstract

We report experimental results on Rydberg facilitation, whereby Rydberg levels can be excited off-resonantly in the presence of a nearby Rydberg atom because of Rydberg-Rydberg interactions, for high-lying $S$, $P$ and $D$ levels in rubidium. Facilitation is detected both through an enhancement of the number of excited atoms for off-resonant excitation (either blue or red detuning) and a positive Mandel $Q$ parameter indicating correlated excitation events (super-Poissonian counting statistics). We also calculate the pair-state potentials for the Rydberg states involved and find that our experimental results agree with the expected facilitation conditions for repulsive potentials (blue detuning) and attractive potentials (red detuning), with $P$ and $D$ states exhibiting facilitation on both sides of the resonance. Finally, we investigate inter-state facilitation between two different Rydberg levels (70 $S$ and 70 $P$).