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 Mølmer-Sørensen two-qubit gates on ${}^{43}{\text{Ca}}^{+}$ hyperfine clock qubits in a cryogenic ($\approx 25\text{K}$) surface trap, driven by near-field microwaves. We achieve gate durations of $154\hat{I}¼\text{s}$ (with $1.0(2)\%$ error) and $331\hat{I}¼\text{s}$ ($0.5(1)\%$ error), which approaches the performance of typical laser-driven gates. In the $331\hat{I}¼\text{s}$ 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.