Batch Optimization of Frequency-Modulated Pulses for Robust Two-Qubit Gates in Ion Chains

TitleBatch Optimization of Frequency-Modulated Pulses for Robust Two-Qubit Gates in Ion Chains
Publication TypeJournal Article
Year of Publication2021
AuthorsM Kang, Q Liang, B Zhang, S Huang, Y Wang, C Fang, J Kim, and KR Brown
JournalPhysical Review Applied
Volume16
Issue2
Date Published08/2021
Abstract

Two-qubit gates in trapped-ion quantum computers are generated by applying spin-dependent forces that temporarily entangle the internal state of the ion with its motion. Laser pulses are carefully designed to generate a maximally entangling gate between the ions while minimizing any residual entanglement between the motion and the ion. The quality of the gates suffers when the actual experimental parameters differ from the ideal case. Here, we improve the robustness of frequency-modulated Mølmer-Sørensen gates to motional mode-frequency offsets by optimizing the average performance over a range of systematic errors using batch optimization. We then compare this method with frequency-modulated gates optimized for ideal parameters that include an analytic robustness condition. Numerical simulations show good performance up to 12 ions, and the method is experimentally demonstrated on a two-ion chain.

DOI10.1103/PhysRevApplied.16.024039
Short TitlePhysical Review Applied