Quasi-phasematching in a poled traveling-wave Josephson parametric amplifier with three-wave mixing

We develop the concept of quasi-phasematching (QPM) in the recently proposed traveling-wave Josephson parametric amplifier (TWJPA) with three wave mixing (3WM). The amplifier is based on a ladder transmission line consisting of flux-biased radio-frequency SQUIDs possessing non-centrosymmetric nonlinearity of χ(2)-type. Due to design with periodically inverted groups of SQUIDs, giving reversal of sign of this nonlinearity, QPM in 3WM process, ωp=ωs+ωi, for pump (ωp), signal (ωs), and idler (ωi) frequency is achieved. Modeling shows that the TWJPA bandwidth is sufficiently large (ca. 0.4ωp) and flat, while propagating unwanted modes, including ω2p=2ωp, ω+=ωp+ωs, ω−=2ωp−ωs, etc., is suppressed with the help of engineered dispersion.