Losses in coplanar waveguide resonators at millikelvin temperatures

TL;DR

This study investigates the temperature and power dependence of losses in coplanar waveguide resonators at millikelvin temperatures, attributing the behavior to material-independent two-level systems in the dielectric.

Contribution

It provides new insights into the power and temperature dependence of losses, highlighting the material-independent nature of two-level systems affecting resonator performance.

Findings

Loss rate becomes power independent below a critical power.

Loss rate increases with decreasing temperature at fixed power.

Two-level systems influence is similar across different materials.

Abstract

We study the loss rate for a set of lambda/2 coplanar waveguide resonators at millikelvin temperatures (20 mK - 900mK) and different applied powers (3E-19 W - 1E-12 W). The loss rate becomes power independent below a critical power. For a fixed power, the loss rate increases significantly with decreasing temperature. We show that this behavior can be caused by two-level systems in the surrounding dielectric materials. Interestingly, the influence of the two-level systems is of the same order of magnitude for the different material combinations. That leads to the assumption that the nature of these two-level systems is material independent.