Broadband parametric amplifiers based on nonlinear kinetic inductance artificial transmission lines
Jiansong Gao, Saptarshi Chaudhuri, Dale Li, Kent D. Irwin, Clint Bockstiegel, Weijie Guo, Xiangliang Liu, Johannes Hubmayr
We present broadband parametric amplifiers based on the kinetic inductance of superconducting NbTiN thin films and an artificial (lumped-element) transmission line architecture. We demonstrate two amplifier designs implementing two different phase matching techniques, periodic impedance loading or resonator phase shifters placed periodically along the transmission line. Our design offers several advantages over previous CPW-based amplifiers, including intrinsic 50 ohm characteristic impedance, natural suppression of higher pump harmonics, lower required pump power, and shorter total trace length. Experimental realizations of both versions of the amplifiers are demonstrated. With a transmission line length of 20 cm, we have achieved gains of 15 dB over a few GHz of bandwidth.