Parallels between chaotic scattering and heating in cold ion-atom collisions

We study the classical dynamics of a Paul-trapped ion in a low-density bath of atoms above 1 μK. We find that lower-energy collisions with more massive atoms, especially at energies less than the initial micromotion heating, are more likely to form atom-ion complexes. These complexes evolve in a fractal structure for every scattering observable, showing nonhyperbolic chaotic dynamics. To explore the chaotic dynamics, we use a GPU-accelerated methodology allowing us to run over 3 × 10⁸ trajectories of a ¹⁷⁴Yb⁺ and different atoms. As a result, after analyzing the dynamics as a function of the atom species, collision energy, trap parameters, and ion-atom potential depth, we find a link between heating and the onset of chaos in the first atom-ion interaction that occurs when a low-density atomic bath is merged with a trapped ion.