MSc Thesis Defense: Ege Selvi, FABRICATION AND CHARACTERIZATION OF SUPERCONDUCTING COPLANAR WAVEGUIDE RESONATORS, Date & Time: 21 July, 2026 – 1:00 PM, Place: FENS L029
FABRICATION AND CHARACTERIZATION OF SUPERCONDUCTING COPLANAR WAVEGUIDE RESONATORS
Ege Selvi
Physics, MSc Thesis, 2026
Thesis Jury
Prof. İsmet İnönü Kaya (Thesis Advisor)
Assoc. Prof. Serkan Ateş
Prof. Özhan Özatay
Date & Time: 21st of July, 2026 – 1:00 PM
Place: FENS L029
Zoom Link: https://sabanciuniv.zoom.us/j/
Keywords : Superconducting CPW resonators, CPW resonator design, Electromagnetic simulation, Cryogenic RF characterization, Duffing dynamics
Abstract
Superconducting coplanar waveguide (CPW) resonators are fundamental microwave components in superconducting quantum device architectures, including microwave kinetic inductance detectors, superconducting quantum amplifiers, and transmon qubits. Their performance is determined by geometric design, capacitive coupling, microwave losses, and the transition from nonlinear to linear response under changing drive power. This thesis presents a simulation guided experimental study of capacitively coupled open-ended half wave superconducting CPW resonators, building on the study framework of Göppl et al.(2008). A design of experiment (DoE) framework was developed to relate resonator length and coupling geometry to the expected microwave response. The CST Studio Suite environment was used for electromagnetic simulations to evaluate resonance formation, length dependent frequency scaling, coupling dependent loaded response, and harmonic mode behavior. The simulations reproduced the expected distributed resonator response in terms of the selected performance indicators. However, comparison with the reference results showed a remaining deviation of approximately 7.5-9.0% indicating that absolute frequency targeting requires further refinement of the effective geometric model and electromagnetic modeling including packaging modes. Fabricated Aluminium CPW resonators were characterized through low temperature transmission measurements at approximately 20~mK. The measured fundamental resonances were found within approximately 1% of the reference frequency scale and were analyzed in terms of resonance frequency, linewidth, transmission response, and loaded quality factor. Power dependent measurements further revealed nonlinear branching behavior interpreted with a nonlinear Duffing model. Overall, this work establishes a practical workflow connecting microwave theory, simulation, fabrication, cryogenic RF characterization, and nonlinear response analysis for future superconducting microwave circuit integration.