Robust quantum control for higher order coupling term in trapped ions

TL;DR

This paper introduces a robust quantum control optimization method for trapped ions that accounts for higher-order coupling terms, achieving high-fidelity two-qubit gates under realistic noise conditions.

Contribution

It presents a novel optimization approach incorporating higher-order effects, improving gate robustness and fidelity in trapped ion quantum computing.

Findings

Achieved infidelity below 10^{-3} under drift and time noise.

Demonstrated the importance of higher-order coupling terms in pulse optimization.

Provided a scheme for more efficient entangled state generation.

Abstract

Trapped ion hardware has made significant progress recently and is now one of the leading platforms for quantum computing. To construct two-qubit gates in trapped ions, experimental manipulation approaches for ion chains are becoming increasingly prevalent. Given the restricted control technology, how implementing high-fidelity quantum gate operations is crucial. Many works in current pulse design optimization focus on ion-phonon and effective ion-ion coupling while ignoring the higher-order expansion impacts of these two terms brought on by experiment defects. This paper proposed a novel robust quantum control optimization method in trapped ions. By introducing the higher-order terms caused by the error into the optimization cost function, we generated an extremely robust Molmer-Sorensen gate with infidelity below $10^{-3}$ under drift noise range $\pm 10$ kHz and time noise range $\pm 0.02$. Our work reveals the vital role of higher-order coupling terms in trapped ion pulse control optimization, especially the higher ion-ion coupling order, and provides a robust optimization scheme for realizing more efficient entangled states in trapped ion platforms.