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

Abstract

Abstract 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 $${\mathcal{F}}=0.99971(3)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>F</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0.99971</mml:mn> <mml:mrow> <mml:mo>(</mml:mo> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:math> , a factor of ≈2 improvement over the best reported performance of any qubit.