Designing Robust Unitary Gates: Application to Concatenated Composite Pulse

TL;DR

This paper introduces a new formalism for designing robust unitary gates that are resistant to systematic errors, leading to a concatenated composite gate with improved fidelity over a broad error range.

Contribution

The authors develop a formalism that generalizes previous work, enabling the design of robust composite unitary gates, including a novel concatenated gate with enhanced error tolerance.

Findings

The new composite gate maintains high fidelity across a wider error range.

The formalism simplifies the design of error-resistant unitary operations.

The concatenated gate outperforms existing composite gates in robustness.

Abstract

We propose a simple formalism to design unitary gates robust against given systematic errors. This formalism generalizes our previous observation [Y. Kondo and M. Bando, J. Phys. Soc. Jpn. 80, 054002 (2011)] that vanishing dynamical phase in some composite gates is essential to suppress amplitude errors. By employing our formalism, we naturally derive a new composite unitary gate which can be seen as a concatenation of two known composite unitary operations. The obtained unitary gate has high fidelity over a wider range of the error strengths compared to existing composite gates.