High-fidelity trapped-ion quantum logic using near-field microwaves

TL;DR

This paper demonstrates a high-fidelity two-qubit quantum logic gate using near-field microwaves in a room-temperature ion trap, achieving a fidelity suitable for fault-tolerant quantum computing.

Contribution

It introduces a novel microwave-driven gate method with dynamic decoupling, enabling stable, high-fidelity operations on atomic clock qubits without nulling the microwave field.

Findings

Gate fidelity of 99.7% achieved

Stable operation with dynamically-decoupled method

Applicable to atomic clock qubits with long coherence times

Abstract

We demonstrate a two-qubit logic gate driven by near-field microwaves in a room-temperature microfabricated ion trap. We measure a gate fidelity of 99.7(1)\%, which is above the minimum threshold required for fault-tolerant quantum computing. The gate is applied directly to $^{43}$Ca$^+$ "atomic clock" qubits (coherence time $T_2^*\approx 50\,\mathrm{s}$) using the microwave magnetic field gradient produced by a trap electrode. We introduce a dynamically-decoupled gate method, which stabilizes the qubits against fluctuating a.c.\ Zeeman shifts and avoids the need to null the microwave field.