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

TL;DR

This paper introduces quasi-phasematching in a Josephson traveling-wave parametric amplifier with three-wave mixing, enhancing bandwidth and suppressing unwanted modes through periodic inversion of SQUID groups.

Contribution

The work demonstrates implementing quasi-phasematching in a JTWPA with 3WM using periodically inverted SQUID groups, improving bandwidth and mode suppression.

Findings

Bandwidth of ~0.4 times pump frequency with flat response

Strong suppression of unwanted modes like second harmonic and mixing products

Modeling confirms effective dispersion engineering

Abstract

We develop the concept of quasi-phasematching (QPM) by implementing it in the recently proposed Josephson traveling-wave parametric amplifier (JTWPA) with three-wave mixing (3WM). The amplifier is based on a ladder transmission line consisting of flux-biased radio-frequency SQUIDs whose nonlinearity is of $\chi^{(2)}$-type. QPM is achieved in the 3WM process, $\omega_p=\omega_s+\omega_i$ (where $\omega_p$, $\omega_s$, and $\omega_i$ are the pump, signal, and idler frequencies, respectively) due to designing the JTWPA to include periodically inverted groups of these SQUIDs that reverse the sign of the nonlinearity. Modeling shows that the JTWPA bandwidth is relatively large (ca. $0.4\omega_p$) and flat, while unwanted modes, including $\omega_{2p}=2\omega_p$, $\omega_+=\omega_p +\omega_s$, $\omega_- = 2\omega_p - \omega_s$, etc., are strongly suppressed with the help of engineered dispersion.