Computational optimization of two-qubit entangling gates in trapped-ion systems under system frequency drift

Abstract

Quantum systems are highly sensitive to environmental noise, leading to drifts in experimental parameters. To enhance entanglement gate fidelity in multiqubit trapped-ion systems, laser amplitude modulation has proven robust against frequency drifts. In this study, we extend this technique by actively optimizing the laser amplitude sequence using a user-defined objective function. This function evaluates fidelities across a broad range of trap frequencies and identifies amplitude solutions under practical laser power constraints. We select the most robust solution—maintaining fidelity above 99.5 % across the widest frequency range—and apply it to various drift types, including linear, sinusoidal, and exponential deviations. Our approach offers a flexible framework for integrating different optimization algorithms and objective functions to maintain high-fidelity gate operations in noisy quantum environments. © 2025 Korean Physical Society