Low-noise amplification atmicrowave frequencies has become increasingly important for the research related to superconducting qubits and nanoelectromechanical systems. The fundamental limit of added noise by a phase-preserving amplifier is the standard quantum limit, often expressed as noise temperature Tq=ℏω/2kB. Towards the goal of the quantum limit, we have developed an amplifier based on intrinsic negative resistance of a selectively damped Josephson junction. Here we present measurement results on previously proposed wide-band microwave amplification and discuss the challenges for improvements on the existing designs. We have also studied flux-pumped metamaterial-based parametric amplifiers, whose operating frequency can be widely tuned by external DC-flux, and demonstrate operation at 2ω pumping, in contrast to the typical metamaterial amplifiers pumped via signal lines at ω.
@article{arxiv.1405.5019,
title = {Advanced Concepts in Josephson Junction Reflection Amplifiers},
author = {Pasi Lähteenmäki and Visa Vesterinen and Juha Hassel and G. S. Paraoanu and Heikki Seppä and Pertti Hakonen},
journal= {arXiv preprint arXiv:1405.5019},
year = {2014}
}