We realize tunable coupling between two superconducting transmission line resonators. The coupling is mediated by a non-hysteretic rf SQUID acting as a flux-tunable mutual inductance between the resonators. From the mode distance observed in spectroscopy experiments, we derive a coupling strength ranging between -320MHz and 37 MHz. In the case where the coupling strength is about zero, the microwave power cross transmission between the two resonators can be reduced by almost four orders of magnitude compared to the case where the coupling is switched on. In addition, we observe parametric amplification by applying a suitable additional drive tone.
@article{arxiv.1508.06758,
title = {Tunable coupling of transmission-line microwave resonators mediated by an rf SQUID},
author = {F. Wulschner and J. Goetz and F. R. Koessel and E. Hoffmann and A. Baust and P. Eder and M. Fischer and M. Haeberlein and M. J. Schwarz and M. Pernpeintner and E. Xie and L. Zhong and C. W. Zollitsch and B. Peropadre and J. -J. Garcia Ripoll and E. Solano and K. Fedorov and E. P. Menzel and F. Deppe and A. Marx and R. Gross},
journal= {arXiv preprint arXiv:1508.06758},
year = {2015}
}