Observation of Rydberg-atom macrodimers: micrometer-sized diatomic molecules

TL;DR

This paper reports the experimental observation of long-range Rydberg-atom macrodimers in ultracold cesium gases, revealing their spectral signatures and confirming the necessity of detailed models for accurate predictions.

Contribution

First experimental observation of Rydberg-atom macrodimers using a three-photon photoassociation scheme and detailed modeling of their long-range interactions.

Findings

Spectral signatures of bound macrodimers are observed.

Experimental results agree with detailed theoretical models.

Macrodimers are distinguished from repulsive states by their ionization behavior.

Abstract

Long-range metastable molecules consisting of two cesium atoms in high Rydberg states have been observed in an ultracold gas. A sequential three-photon two-color photoassociation scheme was employed to form these molecules in states which correlate to $np(n+1)s$ dissociation asymptotes. Spectral signatures of bound molecular states are clearly resolved at the positions of avoided crossings between long-range van der Waals potential curves. The experimental results are in agreement with simulations based on a detailed model of the long-range multipole-multipole interactions of Rydberg-atom pair states. We show that a full model is required to accurately predict the occurrence of bound Rydberg macrodimers. The macrodimers are distinguished from repulsive molecular states by their behavior with respect to spontaneous ionization and possible decay channels are discussed.