Towards Cavity-Assisted Doppler Cooling of Ca⁺ in a Compact Penning Trap

Previous work with ⁴⁰Ca⁺ in radiofrequency Paul traps has demonstrated the viability of free-space Doppler laser cooling using electric-dipole-forbidden (e.g. S → D) optical transitions and high-intensity 729 nm laser beams. Some advantages of this “all-infrared” cooling and detection scheme include background-free ultraviolet fluorescence detection and narrow-linewidth Doppler and sub-Doppler ion cooling. We recently developed a compact Penning ion trap based on thermally-stable SmCo permanent magnets and a printed-circuit-board electrode topology. This compact trap is compatible with an in-vacuum Fabry-Perot optical cavity with high finesse at 729 nm. Here we present numerical simulations and experimental progress towards cavity-enhanced, all-infrared Doppler laser cooling in this novel compact Penning trap apparatus.