The addition of nonlinearity to an harmonic resonator provides a route to complex dynamical behaviour of resonant modes, including coupling between them. We present a superconducting device that makes use of the nonlinearity of Josephson junctions to introduce a controlled, tunable, nonlinear inductance to a thin film coplanar waveguide resonator. Considering the device as a potential quantum optical component in the microwave regime, we create a sensitive bifurcation amplifier and then demonstrate spectroscopy of other resonant modes via the intermode coupling. We find that the sensitivity of the device approaches within a factor two quantitative agreement with a quantum model by Dykman, but is limited by a noise that has its source(s) on-chip.
@article{arxiv.1304.3693,
title = {Bifurcation, mode coupling and noise in a nonlinear multimode superconducting RF resonator},
author = {G. Tancredi and G. Ithier and P. J. Meeson},
journal= {arXiv preprint arXiv:1304.3693},
year = {2014}
}