Barium ions for quantum computation

Barium ion is investigated as a hyperfine qubit. 137Ba + is trapped in a linear Paul trap and laser cooled. Isotope selective photoionization is employed to improve trapping from an isotopically inpure source. Optical pumping into the magnetically insensitive 2S 1/2(F=2) mF = 0 state is shown, and readout by electron shelving into the 2D5/2 is demonstrated both directly and by adiabatic passage. Rabi flops between the 2S1/2 F=1 and F=2 states is accomplished by exposure to 8.037 GHz microwave radiation.;Several methods of locking the cooling lasers have been attempted and are discussed. Stabilization of the infrared laser used to drive the D 5/2 ← S1/2 transition is of particular interest, and several novel technologies are tested in this purpose.