单个 Xmon 量子比特中误差相干性的纯度基准测试研究
Purity benchmarking study of error coherence in a single Xmon qubit
AI总结：
本研究利用纯度基准测试（PB）在 1110 小时内观测单个 Xmon 量子比特，发现非相干误差主要源于宽频带扩散源且对频率不敏感，而相干误差对频率变化和电报噪声敏感，推测由强耦合二能级系统缺陷引起，证明 PB 比传统弛豫时间测量能更全面地捕获量子系统的动态相互作用。
摘要：
在本研究中，我们采用纯度基准测试（PB）来探索超导量子比特系统中门噪声的动力学。在对 Xmon 量子比特长达 1110 小时的观测中，我们同时测量了两个不同工作频率下的相干噪声预算。我们发现，在总体误差率中占主导地位的非相干误差表现出极小的频率依赖性，这表明它们主要源于宽频带、扩散性的非相干误差源。相比之下，相干误差虽然较少发生，但对工作频率变化和电报噪声表现出显著的敏感性。我们推测这种敏感性源于与单个强耦合环境缺陷（被建模为二能级系统）的相互作用，该缺陷会影响量子比特控制参数并导致相干校准误差。我们的结果还表明，PB 提供了更高的灵敏度，能够捕获传统弛豫时间测量无法检测到的额外动力学，从而为捕获量子系统内的动态相互作用提供了一种更全面的方法。这些相干动力学的复杂性凸显了进一步研究的必要性。
英文摘要：
In this study, we employ purity benchmarking (PB) to explore the dynamics of gate noise in a superconducting qubit system. Over 1110 hours of observations on an Xmon qubit, we simultaneously measure the coherence noise budget across two different operational frequencies. We find that incoherent errors, which predominate in overall error rates, exhibit minimal frequency dependence, suggesting they are primarily due to wide-band, diffusive incoherent error sources. In contrast, coherent errors, although less prevalent, show significant sensitivity to operational frequency variations and telegraphic noise. We speculate that this sensitivity is due to interactions with a single strongly coupled environmental defect -- modeled as a two-level system -- which influences qubit control parameters and causes coherent calibration errors. Our results also demonstrate that PB offers improved sensitivity, capturing additional dynamics that conventional relaxation time measurements cannot detect, thus presenting a more comprehensive method for capturing dynamic interactions within quantum systems. The intricate nature of these coherence dynamics underscores the need for further research.
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