论文标题
设备的几何形状和材料特性对超导共面波基谐振器中介电损失的影响
Effects of device geometry and material properties on dielectric losses in superconducting coplanar-waveguide resonators
论文作者
论文摘要
超导Coclanar-WaveGuide（CPW）谐振器是电路量子电动力学（CQED）的关键设备之一。它们的性能可以受到基材和材料界面中的介电损失的限制。需要可靠的建模来帮助设计CQED的低损失CPW结构。我们使用有损耗区域的参与比的有限元元素建模分析了CPW结构中介电损失的几何依赖性。在实际情况下，这些区域的介电常数和损失切线的不确定性在理论上预测的参与率中引入了不确定性。我们提出了一种将损耗模拟与CPW谐振器的两级限制质量因子和共振频率的测量方法结合在一起的方法。也就是说，我们解决了一个反问题，以找到产生测量值的模型参数。可以通过正确设计CPW结构的横截面几何形状来获得高质量的因素，但是低损失CPW谐振器的更准确的建模和设计方法被要求进行重大改进。我们用于解决上述逆问题的非线性优化方法是朝这个方向迈出的一步。
Superconducting coplanar-waveguide (CPW) resonators are one of the key devices in circuit quantum electrodynamics (cQED). Their performance can be limited by dielectric losses in the substrate and in the material interfaces. Reliable modeling is required to aid in the design of low-loss CPW structures for cQED. We analyze the geometric dependence of the dielectric losses in CPW structures using finite-element modeling of the participation ratios of the lossy regions. In a practical scenario, uncertainties in the the dielectric constants and loss tangents of these regions introduce uncertainties in the theoretically predicted participation ratios. We present a method for combining loss simulations with measurements of two-level-system-limited quality factors and resonance frequencies of CPW resonators. Namely, we solve an inverse problem to find model parameters producing the measured values. High quality factors are obtainable by properly designing the cross-sectional geometries of the CPW structures, but more accurate modeling and design methods for low-loss CPW resonators are called for major future improvements. Our nonlinear optimization methodology for solving the aforementioned inverse problem is a step in this direction.
