基于测地线的最优控制用于超导量子比特泄漏抑制
Geodesic-based optimal control for leakage suppression in superconducting qubits
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中文总结 AI 辅助
本研究将基于子黎曼测地线搜索的最优控制方法应用于含泄漏能级的双超导量子比特系统，显著提升了单比特门保真度并降低泄漏，双比特门以稍长时长为代价获得更高保真度。
中文摘要 AI 辅助
超导量子比特通常基于物理非谐LC振荡器的前两个能级。由于此类系统的非谐性通常远低于所涉及的能隙，布居数容易泄漏到更高能态。这正是泄漏误差的特征，其来源多样：从控制平台引起的相干误差到非相干热耗散。在本工作中，我们将一种基于酉群中子黎曼测地线搜索的最优控制方法，应用于一个包含泄漏能级的双超导量子比特系统。我们使用$R_x(\pi/2)$旋转进行单量子比特操作分析，并使用$i$SWAP操作进行双量子比特分析。对于前者，与高斯脉冲和DRAG脉冲相比，所获得的最优脉冲在平均门保真度上表现出显著提升，同时泄漏误差也得到降低，尤其是在短时脉冲情况下。对于$i$SWAP门，尽管泄漏误差大致保持不变，我们仍以略微延长演化时间为代价，获得了相当高的保真度。
英文摘要
Superconducting qubits are often based on the first two energy levels of a physical anharmonic LC oscillator. Since the anharmonicity of such systems is usually much lower than the involved energy gaps, population can easily leak to higher energy states. This is what characterizes leakage errors, and it can have multiple sources: from coherent error induced by the control platform to incoherent thermal dissipation. In this work, we adapt an optimal control method based on sub-Riemannian geodesic search in the unitary group for a system consisting of two superconducting qubits with leakage levels. We use the $R_x(π/2)$ rotation for single-qubit operation analysis, and the $i$SWAP operation for two-qubit analysis. For the former, we find considerable performance improvement in average gate fidelity as well as in the reduction of leakage errors when comparing the obtained optimal pulses with Gaussian and DRAG pulses, especially for short duration pulses. For the $i$SWAP gate, although leakage error remains roughly the same, we manage to obtain considerably higher fidelities with the cost of requiring a slightly longer time evolution.
发表机构
- VTT Technical Research Centre of Finland Ltd（芬兰技术研究中心有限公司）
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