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arXiv · 2307.15841

Pulse optimization for high-precision motional-mode characterization in trapped-ion quantum computers

Qiyao Liang·Mingyu Kang·Ming Li·Yunseong Nam
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Abstract

High-fidelity operation of quantum computers requires precise knowledge of the physical system through characterization. For motion-mediated entanglement generation in trapped ions, it is crucial to have precise knowledge of the motional-mode parameters such as the mode frequencies and the Lamb-Dicke parameters. Unfortunately, the state-of-the-art mode-characterization schemes do not easily render the mode parameters in a sufficiently scalable and accurate fashion, due to the unwanted excitation of adjacent modes in the frequency space when targeting a single mode, an effect known as the \textit{cross-mode coupling}. Here, we develop an alternative scheme that leverages the degrees of freedom in pulse design for the characterization experiment such that the effects of the cross-mode coupling is actively silenced. Further, we devise stabilization methods to accurately characterize the Lamb-Dicke parameters even when the mode frequencies are not precisely known due to experimental drifts or characterization inaccuracies. We extensively benchmark our scheme in simulations of a three-ion chain and discuss the parameter regimes in which the shaped pulses significantly outperform the traditional square pulses.

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Qiyao Liang, Mingyu Kang, Ming Li, Yunseong Nam. 2023-07-29. Pulse optimization for high-precision motional-mode characterization in trapped-ion quantum computers. https://doi.org/10.1088/2058-9565%2Fad3a98

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