Selective loading and laser cooling of rare calcium isotope 43Ca+

We report a method for loading ⁴³Ca⁺ ions selectively in a linear Paul trap using ultraviolet light-emitting-diodes (LEDs) for the second excitation in a two-step photo-ionization process. The difficulty in working with ⁴³Ca⁺ is its low natural abundance (0.135%). In order to load ⁴³Ca⁺ selectively, we utilize the isotope shifts for the 4s^{2 1} S ₀–4s4p¹ P ₁ transition of neutral calcium atoms. We discuss the limitation of the selectivity of the employed photo-ionization scheme and observe spectra from unwanted isotopes as well as that from ⁴³Ca⁺. Purification of ⁴³Ca⁺ is performed by adjusting the detuning of the cooling laser frequency and trapping potential. The method of loading and purification can be used in the application of trapped ⁴³Ca⁺ for an optical frequency standard and for quantum information processing. PACS 32.80.Fb; 32.80.Pj