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

Abstract

Microwave-driven logic is a promising alternative to laser control in scaling trapped-ion based quantum processors. However, such electronic gates have yet to match the speed offered by their laser-driven counterparts. Here, we implement M{\o}lmer-S{\o}rensen two-qubit gates on $^{43}\text{Ca}^+$ hyperfine clock qubits in a cryogenic ($\approx25~\text{K}$) surface trap, driven by near-field microwaves. We achieve gate durations of $154~\mu\text{s}$ (with $1.0(2)\%$ error) and $331~\mu\text{s}$ ($0.5(1)\%$ error), which approaches the performance of typical laser-driven gates. In the $331~\mu\text{s}$ gate, we demonstrate a new Walsh-modulated dynamical decoupling scheme which suppresses errors due to fluctuations in the qubit frequency as well as imperfections in the decoupling drive itself.