ZZ-Interaction-Free Single-Qubit-Gate Optimization in Superconducting Qubits

TL;DR

This paper presents a semi-analytical pulse optimization method for single-qubit gates in superconducting transmon qubits that effectively eliminates ZZ interaction effects, enhancing stability against frequency fluctuations.

Contribution

It introduces a novel semi-analytical pulse design that achieves ZZ-interaction-free single-qubit gates, improving robustness without extra hardware.

Findings

Successfully demonstrated ZZ-interaction-free gates experimentally.

Achieved robustness against MHz-level qubit-frequency fluctuations.

Showed potential for scalable quantum computing with fixed-frequency qubits.

Abstract

Overcoming the issue of qubit-frequency fluctuations is essential to realize stable and practical quantum computing with solid-state qubits. Static ZZ interaction, which causes a frequency shift of a qubit depending on the state of neighboring qubits, is one of the major obstacles to integrating fixed-frequency transmon qubits. Here we propose and experimentally demonstrate ZZ-interaction-free single-qubit-gate operations on a superconducting transmon qubit by utilizing a semi-analytically optimized pulse based on a perturbative analysis. The gate is designed to be robust against slow qubit-frequency fluctuations. The robustness of the optimized gate spans a few MHz, which is sufficient for suppressing the adverse effects of the ZZ interaction. Our result paves the way for an efficient approach to overcoming the issue of ZZ interaction without any additional hardware overhead.