# Photo-association of trilobite Rydberg molecules via resonant spin-orbit coupling

## TL;DR

This paper introduces a new photo-association method for polar trilobite Rydberg molecules using resonant spin-orbit coupling, enabling the formation of molecules with large electric dipole moments.

## Contribution

The study demonstrates a novel resonant coupling technique to photo-associate trilobite molecules, overcoming previous limitations due to their high angular momentum character.

## Key findings

- Achieved high-resolution spectroscopy of trilobite molecules.
- Measured a dipole moment of approximately 135 Debye.
- Validated results with theoretical Fermi-model predictions.

## Abstract

We report on a novel method for photo-association of strongly polar trilobite Rydberg molecules. This exotic ultralong-range dimer, consisting of a ground-state atom bound to the Rydberg electron via electron-neutral scattering, inherits its polar character from the admixture of high angular momentum electronic orbitals. The absence of low-$L$ character hinders standard photo-association techniques. Here, we show that for suitable principal quantum numbers resonant coupling of the orbital motion with the nuclear spin of the perturber, mediated by electron-neutral scattering, hybridizes the trilobite molecular potential with the more conventional ${\rm{S}}$-type molecular state. This provides a general path to associate trilobite molecules with large electric dipole moments, as demonstrated via high-resolution spectroscopy. We find a dipole moment of 135(45) D for the trilobite state. Our results are compared to theoretical predictions based on a Fermi-model.