Cryogenic ion trap system for high-fidelity near-field microwave-driven quantum logic

Abstract: We report the design, fabrication, and characterization of a cryogenic ion trap system for the implementation of quantum logic driven by near-field microwaves. The trap incorporates an on-chip microwave resonator with an electrode geometry designed to null the microwave field component that couples directly to the qubit, while giving a large field gradient for driving entangling logic gates. We map the microwave field using a single $^{43}$Ca$^+$ ion, and measure the ion trapping lifetime and motional mode heating rates for one and two ions.