How to integrate a miniature optical cavity in a linear ion trap: Shielding dielectrics and trap symmetry

Scaling up qubit numbers remains a major challenge across all quantum computing platforms, including trapped-ion systems. A modular approach seems promising, but hinges on efficient interfaces like miniature optical cavities. Despite decades of effort, a lack of understanding of the relevant challenges has precluded integration. This study identifies key obstacles posed by dielectric optical cavities, and uncovers a critical component that alleviates their negative effects. The findings provide a clear roadmap for improving ion-trap interfacing and suggest that three-dimensional traps are more suitable than planar ones.