Parametric amplification with weak-link nonlinearity in superconducting microresonators

TL;DR

This paper demonstrates parametric amplification in superconducting microresonators caused by weak-link nonlinearity, showing large gain and signal squeezing near bifurcation points, supported by experimental results and Kerr-based theory.

Contribution

It introduces a new approach to parametric amplification using weak-link nonlinearity in superconducting microresonators, with experimental validation and theoretical modeling.

Findings

Large parametric gain observed near bifurcation point

Phase-dependent gain and signal squeezing confirmed

Experimental results align with Kerr nonlinearity theory

Abstract

Nonlinear kinetic inductance in a high Q superconducting coplanar waveguide microresonator can cause a bifurcation of the resonance curve. Near the critical pumping power and frequency for bifurcation, large parametric gain is observed for signals in the frequency band near resonance. We show experimental results on signal and intermodulation gain which are well described by a theory of the parametric amplification based on a Kerr nonlinearity. Phase dependent gain, or signal squeezing, is verified with a homodyne detection scheme.