Temperature Dependence of the Frequency and Noise of Superconducting Coplanar Waveguide Resonators

TL;DR

This study investigates how temperature affects the resonance frequency and noise in superconducting niobium coplanar waveguide resonators, revealing that noise decreases significantly with increasing temperature and aligns with TLS models.

Contribution

It provides experimental evidence linking TLS to noise in superconducting resonators and details their temperature-dependent behavior at millikelvin temperatures.

Findings

Noise decreases by nearly two orders of magnitude from 120 mK to 1200 mK.

Resonance frequency variation matches TLS model predictions.

Results have implications for quantum computing and photon detection applications.

Abstract

We present measurements of the temperature and power dependence of the resonance frequency and frequency noise of superconducting niobium thin-film coplanar waveguide resonators, carried out at temperatures well below the superconducting transition (T_{c}=9.2 K). The noise decreases by nearly two orders of magnitude as the temperature is increased from 120 to 1200 mK, while the variation of the resonance frequency with temperature over this range agrees well with the standard two-level system (TLS) model for amorphous dielectrics. These results support the hypothesis that TLS are responsible for the noise in superconducting microresonators, and have important implications for resonator applications such as qubits and photon detectors.