We have developed a Josephson parametric amplifier, comprising a superconducting coplanar waveguide resonator terminated by a dc SQUID (superconducting quantum interference device). An external field (the pump, ∼20 GHz) modulates the flux threading the dc SQUID, and, thereby, the resonant frequency of the cavity field (the signal, ∼10 GHz), which leads to parametric signal amplification. We operated the amplifier at different band centers, and observed amplification (17 dB at maximum) and deamplification depending on the relative phase between the pump and the signal. The noise temperature is estimated to be less than 0.87 K.
@article{arxiv.0808.1386,
title = {Flux-driven Josephson parametric amplifier},
author = {T. Yamamoto and K. Inomata and M. Watanabe and K. Matsuba and T. Miyazaki and W. D. Oliver and Y. Nakamura and J. S. Tsai},
journal= {arXiv preprint arXiv:0808.1386},
year = {2008}
}