Work

A Versatile Analytical Model for Fast and Accurate Determination of Feedline-Coupled Resonators for Superconducting Qubit Readout

Year: 2025

Type: article

Abstract: Superconducting quantum chips commonly utilize quarter-wavelength ($\lambda /4$) transmission line resonators as readout circuits. An analytical model for the accurate determination of resonance frequencies and couplingQ-factors of feedline-coupled superconducting resonators is introduced. The model leverages four-port microwave network analysis, integrating boundary conditions and conformal mapping techniques to compute even- and odd-mode impedances in edge-coupled coplanar waveguide (CPW) structures. Its versatility allows application to both planar and 3-D heterogeneous architectures, making it a powerful tool for resonator design. To validate the model, a test chip with$\lambda /4$resonators of varying geometries is fabricated and measured in a cryogenic environment. Comparisons with finite element method (FEM) simulations and experimental measurements confirm the model’s accuracy, with resonance frequencies and couplingQ-factors aligning closely across configurations. This proposed model facilitates the design of superconducting resonators in readout circuits for more effective, scalable, and adaptable quantum computing architectures.

Source: IEEE Transactions on Microwave Theory and Techniques

DOI: 10.1109/tmtt.2025.3578414