Single-qubit gates with errors at the $10^{-7}$ level

Abstract

We report the achievement of single-qubit gates with sub-part-per-million error rates, in a trapped-ion ${}^{43}$Ca${}^{+}$ hyperfine clock qubit. We explore the speed/fidelity trade-off for gate times $4.4\le t_g\le 35\hat{I}¼$s, and benchmark a minimum error per Clifford gate of $1.5(4)\times 10^{-7}$. Calibration errors are suppressed to $<10^{-8}$, leaving qubit decoherence ($T_2\approx 70$ s), leakage, and measurement as the dominant error contributions. The ion is held above a microfabricated surface-electrode trap which incorporates a chip-integrated microwave resonator for electronic qubit control; the trap is operated at room temperature without magnetic shielding.