Long-range interactions between ultracold atoms and molecules including atomic spin-orbit

TL;DR

This paper provides a theoretical analysis of long-range electrostatic interactions between ultracold alkali-metal dimers and excited atoms, considering atomic spin-orbit effects and their impact on atom-molecule dynamics.

Contribution

It extends the theoretical framework to include various regimes of atomic spin-orbit effects in ultracold atom-molecule interactions.

Findings

Interaction involves quadrupole-quadrupole and dipole-dipole effects.

Atomic spin-orbit effects can significantly alter interaction dynamics.

Complex atom-molecule behavior at large distances may influence ultracold collision models.

Abstract

We investigate theoretically the long-range electrostatic interactions between a ground-state homonuclear alkali-metal dimer and an excited alkali-metal atom taking into account its fine-structure. The interaction involves the combination of first-order quadrupole-quadrupole and second-order dipole-dipole effects. Depending on the considered species, the atomic spin-orbit may be comparable to the atom-molecule electrostatic energy and to the dimer rotational structure. Here we extend our general description in the framework of the second-order degenerate perturbation theory [M. Lepers and O. Dulieu, Eur. Phys. J. D, 2011] to various regimes induced by the magnitude of the atomic spin-orbit. A complex dynamics of the atom-molecule may take place at large distances, which may have consequences for the search for an universal model of ultracold inelastic collisions as proposed for instance in [Z. Idziaszek and P. S. Julienne, Phys. Rev. Lett. \textbf{104}, 113202 (2010)].