The authors demonstrate quadratic mixing of weak time harmonic electromagnetic fields applied to Superconducting Quantum Interference Filters, manufactured from high-Tc grain boundary Josephson junctions and operated in active microcooler. The authors use the parabolic shape of the dip in the dc-voltage output around B=0 to mix \emph{quadratically} two external rf-signals, at frequencies f1 and f2 well below the Josephson frequency fJ, and detect the corresponding mixing signal at ∣f1−f2∣. Quadratic mixing takes also place when the SQIF is operated without magnetic shield. The experimental results are well described by a simple analytical model based on the adiabatic approximation.
@article{arxiv.cond-mat/0602590,
title = {Quadratic Mixing of Radio Frequency Signals using Superconducting Quantum Interference Filters},
author = {P. Caputo and J. Tomes and J. Oppenlaender and Ch. Haeussler and A. Friesch and T. Traeuble and N. Schopohl},
journal= {arXiv preprint arXiv:cond-mat/0602590},
year = {2007}
}