Pinch Resonances in a Radio Frequency Driven SQUID Ring-Resonator System

TL;DR

This paper investigates the nonlinear frequency response of a SQUID ring coupled to an rf resonator, revealing pinch resonances characterized by opposed fold bifurcations that can be explained through nonlinear equations.

Contribution

It provides experimental evidence and theoretical analysis of pinch resonances in a SQUID ring-resonator system, a novel nonlinear phenomenon in this context.

Findings

Pinch off lineshapes observed in the resonance response.

Existence of pinch resonances as solutions of nonlinear equations.

Experimental data supporting the theoretical model.

Abstract

In this paper we present experimental data on the frequency domain response of a SQUID ring (a Josephson weak link enclosed by a thick superconducting ring) coupled to a radio frequency (rf) tank circuit resonator. We show that with the ring weakly hysteretic the resonance lineshape of this coupled system can display opposed fold bifurcations that appear to touch (pinch off). We demonstrate that for appropriate circuit parameters these pinch off lineshapes exist as solutions of the non-linear equations of motion for the system.