Demonstration of RIP gates in a quantum processor with negligible transverse coupling

TL;DR

This paper demonstrates a superconducting quantum processor with a novel coupler that eliminates transverse qubit coupling over a wide frequency range, enabling high-fidelity multi-qubit operations without flux bias tuning.

Contribution

Introduction of a multi-mode linear bus interferometer coupler that suppresses transverse coupling in a six-qubit superconducting processor without flux bias tuning.

Findings

Negligible static transverse coupling achieved across the device.

High-fidelity simultaneous two-qubit gates with fidelities up to 99.4%.

Low ZZ interaction rates below 600 Hz across the qubit spectrum.

Abstract

Here, we report the experimental demonstration of a novel multi-mode linear bus interferometer (LBI) coupler in a six qubit superconducting quantum processor. A key feature of this coupler is an engineered multi-path interference which eliminates transverse coupling between qubits over a wide frequency range. This negligible static coupling is achieved without any flux bias tuning, and greatly reduces the impact of qubit frequency collisions. We achieve good simultaneous single qubit gate operation and low ZZ rates (below 600 Hz) across the device without staggering qubit frequencies, even in cases where qubits are as close as 10 MHz. Multi-qubit interactions are still possible through the coupler using microwave-driven resonator induced phase gates, which we utilize to demonstrate simultaneous two qubit gates with fidelities as high as 99.4%