Isotope-selective Laser Ablation Loading of Trapped Barium Ions

Loading an ion into an ion trap is the first step of any trapped ion experiments. We report on a laser ablation technique for loading barium ions. This technique has several advantages over the pioneering technique of loading via oven heating, most notably the more efficient use of the target material, the ability to use a compound form material, and lower heat load. Naturally occurring barium has a significant spread of its isotopic distribution, with Ba-138 being the most abundant at 71.7%. To enable targeted loading of a select isotope, we exploit the different first excitation energies of neutral barium isotopes in a two-step photoionization technique. We present the performance of barium ion loading by laser ablation of a BaCl₂ target substrate. The loading efficiency and consistency are characterized. We also demonstrate a higher loading selectivity of Ba-137 than its natural abundance of 11.2%.