Analysis of high quality superconducting resonators: consequences for TLS properties in amorphous oxides

TL;DR

This paper investigates how interactions among two-level systems (TLS) in amorphous oxides affect superconducting resonator performance, providing insights into TLS properties and their impact on device noise.

Contribution

It presents experimental data on loss and noise in Nb resonators with different surface treatments, offering new understanding of TLS behavior in amorphous oxides.

Findings

TLS interactions influence resonator noise and loss

Pt capping modifies TLS properties and reduces noise

Estimated TLS concentration and dipole moments

Abstract

$1/f$ noise caused by microscopic Two-Level Systems (TLS) is known to be very detrimental to the performance of superconducting quantum devices but the nature of these TLS is still poorly understood. Recent experiments with superconducting resonators indicates that interaction between TLS in the oxide at the film-substrate interface is not negligible. Here we present data on the loss and $1/f$ frequency noise from two different Nb resonators with and without Pt capping and discuss what conclusions can be drawn regarding the properties of TLS in amorphous oxides. We also estimate the concentration and dipole moment of the TLS.