Low-loss waveguides are required for quantum communication at distances beyond the chip-scale for any low-temperature solid-state implementation of quantum information processors. We measure and analyze the attenuation constant of commercially available microwave-frequency waveguides down to millikelvin temperatures and single photon levels. More specifically, we characterize the frequency-dependent loss of a range of coaxial and rectangular microwave waveguides down to $0.005\ \mbox{dB}/\mbox{m}$ using a resonant-cavity technique. We study the loss tangent and relative permittivity of commonly used dielectric waveguide materials by measurements of the internal quality factors and their comparison with established loss models. The results of our characterization are relevant for accurately predicting the signal levels at the input of cryogenic devices, for reducing the loss in any detection chain, and for estimating the heat load induced by signal dissipation in cryogenic systems.

中文翻译：

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表征低温下同轴和矩形微波频率波导的衰减。


对于量子信息处理器的任何低温固态实现，超芯片级距离的量子通信都需要低损耗波导。我们测量和分析市售微波频率波导低至毫开尔文温度和单光子水平的衰减常数。更具体地说，我们使用谐振腔技术表征了一系列同轴和矩形微波波导的频率相关损耗低至 $0.005\ \mbox{dB}/\mbox{m}$。我们通过测量内部质量因素并将其与已建立的损耗模型进行比较来研究常用介电波导材料的损耗角正切和相对介电常数。我们的表征结果对于准确预测低温设备输入端的信号水平、减少任何检测链中的损耗以及估计低温系统中信号耗散引起的热负荷相关。