Hyperfine and optical barium ion qubits
Matthew J. Dietrich, Nathan Kurz, Thomas Noël, Gang Shu, B. B. Blinov · Physical Review A · 2010
State preparation, qubit rotation, and high fidelity readout are demonstrated for two different $^{137}\mathrm{Ba}{}^{+}$ qubit types. First, an optical qubit on the narrow $6{S}_{1/2}$ to $5{D}_{5/2}$ transition at 1.76 $\ensuremath{\mu}$m is implemented. Then, leveraging the techniques developed there for readout, a ground-state hyperfine qubit using the magnetically insensitive transition at 8 GHz is accomplished.