Robust and fast microwave-driven quantum logic for trapped-ion qubits

Microwave-driven logic is a promising alternative to laser control in scaling trapped-ion based quantum processors. We implement Mølmer-Sørensen two-qubit gates on <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msup><a:mrow/><a:mn>43</a:mn></a:msup><a:msup><a:mrow><a:mi>Ca</a:mi></a:mrow><a:mo>+</a:mo></a:msup></a:math> hyperfine clock qubits in a cryogenic <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mo>(</b:mo><b:mo>≈</b:mo><b:mn>25</b:mn><b:mo> </b:mo><b:mi mathvariant="normal">K</b:mi><b:mo>)</b:mo></b:math> surface trap, driven by near-field microwaves. We achieve gate durations of 154 µs [with 1.0(2)% error] and 331 µs [0.5(1)% error], which approaches the performance of typical laser-driven gates. In the 331 µs gate, we demonstrate a Walsh-modulated dynamical decoupling scheme which suppresses errors due to fluctuations in the qubit frequency as well as imperfections in the decoupling drive itself. Published by the American Physical Society 2024