Superconducting Resonators with Parasitic Electromagnetic Environments

TL;DR

This paper investigates how parasitic electromagnetic fields degrade the quality factor of superconducting resonators and demonstrates methods to reduce these losses, achieving high Q-factors and analyzing power and temperature effects.

Contribution

It provides a detailed analysis of parasitic electromagnetic effects on superconducting resonators and introduces strategies to mitigate these losses, improving resonator performance.

Findings

Parasitic electromagnetic fields significantly suppress resonator Q-factors.

Reducing parasitic losses leads to a Lorentzian lineshape and Q-factor of 2.4 x 10^5.

Resonance frequency shifts depend on input power and temperature due to two-level systems.

Abstract

Parasitic electromagnetic fields are shown to strongly suppress the quality (Q)-factor of superconducting coplanar waveguide resonators via non-local dissipation in the macroscopic environment. Numerical simulation and low temperature measurements demonstrate how this parasitic loss can be reduced, establishing a Lorentzian lineshape in the resonator frequency response and yielding a loaded Q-factor of 2.4 x 10^5 for niobium devices on sapphire substrates. In addition, we report the dependence of the Q and resonance frequency shift Delta f_0 with input power and temperature in the limit where loss from two-level systems in the dielectric dominate.