High-fidelity manipulation of a qubit enabled by a manufactured nucleus

The recently demonstrated trapping and laser cooling of 133 Ba + has opened the door to the use of this nearly ideal atom for quantum information processing. However, before high-fidelity qubit operations can be performed, a number of unknown state energies are needed. Here, we report measurements of the 2 P 3/2 and 2 D 5/2 hyperfine splittings, as well as the 2 P 3/2 ↔ 2 S 1/2 and 2 P 3/2 ↔ 2 D 5/2 transition frequencies. Using these transitions, we demonstrate high-fidelity 133 Ba + hyperfine qubit manipulation with electron shelving detection to benchmark qubit state preparation and measurement (SPAM). Using single-shot, threshold discrimination, we measure an average SPAM fidelity of F=0.99971(3) F = 0.99971 ( 3 ) , a factor of ≈2 improvement over the best reported performance of any qubit.