发表机构
Cornell University; Universität Regensburg（康奈尔大学; 雷根斯堡大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究提出无需制备的倒装芯片传感方案，评估锗基电介质与超导体的微波损耗，明确材料约束，为平面Ge异质结构微波电路提供设计指导，还展示了超导量子电路新材料的快速测试方法。
AI 中文摘要
我们提出一种基于倒装芯片（flip-chip）的传感方案，用于测量量子技术中目标材料相关的有效微波损耗，无需在被测材料上进行任何器件制备。采用该方法，我们量化了应变工程调控的Ge/SiGe量子阱异质结构的微波损耗，并研究了其Ge衬底与中间层产生的损耗。所制备的微波谐振器的品质因子，与从倒装芯片传感测量中独立提取的电介质材料损耗相符。我们进一步研究了通过沉积Pt薄膜热反应制备的超导体铂硅锗（PtSiGe），发现其具有高微波损耗，限制了所研究的这类薄膜作为高品质谐振器应用中唯一超导体的适用性。通过在反应前用Nb包覆Pt，我们观察到微波损耗大幅降低，且传输临界温度提升近三倍。两种超导薄膜的微波损耗温度依赖性均与能隙不均匀性一致。这些结果明确了材料选择的约束条件，为平面Ge异质结构上的微波电路提供了设计指导，并展示了一种用于超导量子电路新材料的快速周转测试方法。
英文摘要
We present a flip-chip-based sensing scheme to measure effective microwave losses associated with target materials for quantum technologies, without requiring any device fabrication on the material under test. Using this approach, we quantify the microwave losses of a strain-engineered Ge/SiGe quantum well heterostructure and investigate losses arising from its Ge substrate and intermediate layers. The quality factors of the fabricated microwave resonators agree with the losses of dielectric materials independently extracted from flip-chip sensing measurements. We further study the superconductor platinum silicon germanide (PtSiGe) prepared by thermal reaction with a deposited Pt film, finding high microwave losses that limit the suitability of the films studied here as the sole superconductor for high-quality resonator applications. By coating Pt with Nb prior to the reaction, we observe a substantial reduction in microwave loss and a nearly three-fold enhancement of the transport critical temperature. The temperature dependence of the microwave loss is consistent with gap inhomogeneity in both superconducting films. These results identify constraints on material choices, provide design guidance for microwave circuits on planar Ge heterostructures, and demonstrate a fast-turnaround testing method for new materials for superconducting quantum circuits.
