Josephson parametric amplifier with Chebyshev gain profile and high saturation
Ryan Kaufman, T. White, M. I. Dykman, A. Iorio, G. Sterling, Sabrina Hong, Alex Opremcak, Andreas Bengtsson, Lara Faoro, Joseph C. Bardin, Tim Burger, Robert Gasca, Ofer Naaman
Abstract
We demonstrate a Josephson parametric amplifier design with a band-pass impedance-matching network based on a third-order Chebyshev prototype. We measured eight amplifiers operating at 4.6 GHz that exhibit gains of 20 dB with less than 1-dB gain ripple and bandwidth up to 500 MHz. The amplifiers further achieve high-output-saturation powers around $\ensuremath{-}73\phantom{\rule{0.2em}{0ex}}\mathrm{dBm}$ based on the use of rf superconducting quantum interference device arrays as their nonlinear element. We characterize the system readout efficiency and its signal-to-noise ratio near saturation using a Sycamore processor, finding the data consistent with near quantum limited noise performance of the amplifiers. In addition, we measure the amplifiers' intermodulation distortion in two-tone experiments as a function of input power and intertone detuning, and observe excess distortion at small detuning with a pronounced dip as a function of signal power, which we interpret in terms of power-dependent dielectric losses.