Long-range Rydberg-Rydberg interactions in calcium, strontium and ytterbium

TL;DR

This paper calculates and analyzes long-range Rydberg-Rydberg interactions in calcium, strontium, and ytterbium, revealing unique interaction characteristics and identifying specific resonances, with implications for quantum information and atomic physics.

Contribution

It provides the first detailed perturbative calculations of Rydberg interactions for these alkaline-earth-like atoms, including quantum defects and interaction characteristics.

Findings

Qualitative differences from alkali metals in interaction behavior

Identification of two F"orster resonances in strontium

Attractive isotropic interactions in strontium's $^1S_0$ states

Abstract

Long-range dipole-dipole and quadrupole-quadrupole interactions between pairs of Rydberg atoms are calculated perturbatively for calcium, strontium and ytterbium within the Coulomb approximation. Quantum defects, obtained by fitting existing laser spectroscopic data, are provided for all $S$, $P$, $D$ and $F$ series of strontium and for the $^3P_2$ series of calcium. The results show qualitative differences with the alkali metal atoms, including isotropically attractive interactions of the strontium $^1S_0$ states and a greater rarity of F\"orster resonances. Only two such resonances are identified, both in triplet series of strontium. The angular dependence of the long range interaction is briefly discussed.