Full control of superconducting qubits with combined on-chip microwave and flux lines

TL;DR

This paper introduces an integrated control line combining microwave and flux signals for superconducting qubits, enabling efficient single-qubit gates and flux control with high fidelity, facilitating scalable quantum computing.

Contribution

It presents a novel integrated 'XYZ line' that combines microwave and flux control, demonstrating high-fidelity gates and potential for scalable quantum processor control.

Findings

Achieved single-qubit gate fidelity above 99.5%.

Measured qubit relaxation times comparable to separate control line devices.

Demonstrated potential for implementing parametric entangling gates.

Abstract

As the field of quantum computing progresses to larger-scale devices, multiplexing will be crucial to scale quantum processors. While multiplexed readout is common practice for superconducting devices, relatively little work has been reported about the combination of flux and microwave control lines. Here, we present a method to integrate a microwave line and a flux line into a single "XYZ line". This combined control line allows us to perform fast single-qubit gates as well as to deliver flux signals to the qubits. The measured relaxation times of the qubits are comparable to state-of-art devices employing separate control lines. We benchmark the fidelity of single-qubit gates with randomized benchmarking, achieving a fidelity above 99.5%, and we demonstrate that XYZ lines can in principle be used to run parametric entangling gates.