Barium Ions for omg-style Trapped-Ion Quantum Information

Most quantum information experiments with trapped ions encode the qubit either between two Zeeman or hyperfine sublevels of the ground electronic state or between the ground state and a long-lived metastable state. A third category is the metastable qubit, in which quantum information is encoded in sublevels of the metastable state. Qubits in this manifold would be largely insensitive to scattered laser light addressing a neighboring qubit in the ground state manifold, potentially enabling quasi-dual-species operation in a chain of identical ions. Barium-133 ions have accessible visible and infrared transition wavelengths, nuclear spin I = 1/2, and a metastable state with a 26 second lifetime, making them appealing for this application. However, this isotope is radioactive, with a 10.5-year half-life. Photo-ionization of neutral barium atoms produced by laser ablation of a barium compound could enable isotope-selective loading of a small volume source, improving the ease of working with radioactive material. We characterize the production of neutral and ionic barium by laser ablation from both BaCl₂ and BaTiO₃.  We also discuss progress loading, cooling, and coherently controlling barium ions produced by such a method in a surface electrode trap.