Motional resonances of three-dimensional dual-species Coulomb crystals

TL;DR

This study explores the complex motional resonances in dual-species Coulomb crystals of $^9$Be$^+$ and $^{24}$Mg$^+$ ions, combining experiments and simulations to better understand their dynamics and spectral features.

Contribution

It introduces a simple mechanical coupling model that explains the secular spectra of mixed ion crystals, aiding in their identification.

Findings

Secular spectra of mixed crystals differ from pure ones.

The proposed model explains key spectral features.

Findings improve species identification in Coulomb crystals.

Abstract

We investigate the motional resonances of dual-species Coulomb crystals comprised of $^9$Be$^+$ and $^{24}$Mg$^+$ ions held in a 4-rod linear Paul trap. Our experimental data and simulations show that the secular motion of such mixed crystals has rich dynamics. Their secular spectra can differ significantly from those of pure ion crystals. We propose a simple model based on mechanical coupling with Coulomb interactions between the two different ion species that explains many features of the secular spectrum. Our findings contribute to a more reliable identification of the ion species in mixed crystals.