Microwave transmissions through superconducting coplanar waveguide resonators with different coupling configurations

TL;DR

This paper investigates how different coupling configurations in superconducting niobium coplanar waveguide resonators affect their microwave transmission properties at millikelvin temperatures, highlighting variations in quality factors and transmission peak shapes.

Contribution

It introduces two types of superconducting coplanar waveguide resonators with distinct coupling capacitors and analyzes their microwave transmission characteristics at cryogenic temperatures.

Findings

Significant difference in loaded quality factors between the two resonator types

Transmission peaks deviate from standard Lorentzian profiles

Classical ABCD matrix approach effectively fits the measured data

Abstract

We design and fabricate two types of superconducting niobium coplanar waveguide microwave resonators with different coupling capacitors on high purity Si substrates. Their microwave transmissions are measured at the temperatures of 20 mK. It is found that these two types of resonators possess significantly-different loaded quality factors; one is $5.6\times{10}^{3}$, and the other is $4.0\times{10}^{4}$. The measured data are fitted well by classical ABCD matrix approach. We found that the transmission peak deviates from the standard Lorentizian with a frequency broadening.