Isotope-selective laser ablation ion-trap loading of Ba-137(+) using a BaCl2 target

The Ba-133(+) ion is a promising candidate as a high-fidelity qubit, and the Ba-133(+) isotope is promising as a high-fidelity qudit (d > 2). Barium metal is very reactive, and Ba-133(+) is radioactive and can only be sourced in small quantities, so the most commonly used loading method, oven heating, is less suited for barium and is currently not possible for Ba-133(+). Pulsed laser ablation solves both of these problems by utilizing compound barium sources while also giving some distinct advantages, such as fast loading, less displaced material, and lower heat load near the ion trap. Because of the relatively low abundances of the isotopes of interest, a two-step photoionization technique is used, which gives us the ability to selectively load isotopes. Characterization of the ablation process for our BaCl2 targets are presented, including observation of neutral and ion ablation-fluence regimes, preparation and conditioning, lifetimes of ablation spots, and plume velocity distributions. We show that by using laser ablation on BaCl2 salt targets with a two-step photoionization method, we can produce and trap barium ions reliably. Furthermore, we demonstrate that with our photoionization method, we can trap Ba-133(+) with an enhanced selectivity compared to its natural abundance.