Barium Ions for Quantum Computation

Abstract

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 2S1/2(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 D5/2 !S1/2 transition is of particular interest, and several novel technologies are tested in this purpose.