Local gradient optimization of leakage-suppressing entangling sequences

TL;DR

This paper introduces a gradient-based method to optimize single-qubit rotations within two-qubit gates, effectively suppressing logical and leakage errors across different quantum systems.

Contribution

It presents a general, system-independent optimization scheme for improving two-qubit gate fidelity by minimizing errors through tailored single-qubit rotations.

Findings

Sequence fidelity is sensitive to single-qubit operation imperfections.

The method effectively reduces logical and leakage errors.

Applicability is broad across various quantum hardware implementations.

Abstract

We use a gradient-based optimization scheme to find single-qubit rotations to be interwoven between timesteps of a noisy logical two-qubit entangling gate in order to suppress arbitrary logical and leakage errors in the two-qubit gate. We show how the sequence fidelity is affected by imperfections in the single-qubit operations, as well as by various relative strengths of the logical and leakage noise. Our approach is completely general and system-independent, allowing for application to any two-qubit system regardless of the experimental implementation details.