Superconducting quantum circuits are one of the leading quantum computing platforms. To advance superconducting quantum computing to a point of practical importance, it is critical to identify and address material imperfections that lead to decoherence. Here, we use terahertz scanning near-field optical microscopy to probe the local dielectric properties and carrier concentrations of wet-etched aluminum resonators on silicon, one of the most characteristic components of the superconducting quantum processors. Using a recently developed vector calibration technique, we extract the THz permittivity from spectroscopy in proximity to the microwave feedline. Fitting the extracted permittivity to the Drude model, we find that silicon in the etched channel has a carrier concentration greater than buffer oxide etched silicon and we explore post-processing methods to reduce the carrier concentrations. Our results show that near-field THz investigations can be used to quantitatively evaluate and identify inhomogeneities in quantum devices.

中文翻译：

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共面微波谐振器的近场太赫兹纳米技术

超导量子电路是领先的量子计算平台之一。为了将超导量子计算推进到具有实际意义的程度，识别和解决导致退相干的材料缺陷至关重要。在这里，我们使用太赫兹扫描近场光学显微镜来探测硅上湿蚀刻铝谐振器的局部介电特性和载流子浓度，硅是超导量子处理器最具特征的组件之一。使用最近开发的矢量校准技术，我们从微波馈线附近的光谱中提取 THz 介电常数。将提取的介电常数拟合到 Drude 模型，我们发现蚀刻通道中的硅的载流子浓度高于缓冲氧化物蚀刻的硅，我们探索了后处理方法来降低载流子浓度。我们的结果表明，近场太赫兹研究可用于定量评估和识别量子器件中的不均匀性。