Novel Self-Sustained Modulation in Superconducting Stripline Resonators

TL;DR

This paper investigates thermal instability and self-sustained power modulation in a superconducting NbN resonator with a microbridge, combining experimental measurements and a hot spot theoretical model.

Contribution

It introduces a new understanding of self-sustained modulation caused by thermal effects in superconducting resonators, supported by experimental and theoretical analysis.

Findings

Identification of a specific frequency-amplitude zone with no steady state

Observation of self-sustained power modulation in the resonator

Good agreement between experimental results and the hot spot model

Abstract

We study thermal instability in a driven superconducting NbN resonator integrated with a microbridge. A monochromatic input drive is injected into the resonator and the response is measured as a function of the frequency and amplitude of the drive. Inside a certain zone in the frequency-amplitude plane the system has no steady state, and consequently self-sustained modulation of the reflected power off the resonator is generated. A theoretical model, according to which the instability originates by a hot spot forming in the microbridge, exhibits a good quantitative agreement with the experimental results.