Numerical analysis of a three-wave-mixing Josephson traveling-wave parametric amplifier with engineered dispersion loadings

TL;DR

This paper models a Josephson traveling-wave parametric amplifier with engineered dispersion loadings, demonstrating wide bandwidth and gain suppression of unwanted tones, advancing practical quantum-limited amplification technology.

Contribution

It introduces a detailed numerical model of a JTWPA with engineered dispersion, optimizing bandwidth and suppression of spurious signals for practical applications.

Findings

Achieves 3-9 GHz bandwidth with less than ±2 dB gain ripple.

Effectively suppresses higher harmonic tones such as 2ωp and ωp+ωs.

Provides a practical design approach for high-performance quantum amplifiers.

Abstract

The recently proposed Josephson traveling-wave parametric amplifier (JTWPA) based on a ladder transmission line consisting of radio-frequency SQUIDs and exploiting three-wave mixing (3WM), has great potential in achieving both a gain of 20 dB and a flat bandwidth of at least 4 GHz. To realize this concept in practical amplifiers we model the advanced JTWPA circuit with periodic modulation of the circuit parameters (engineered dispersion loadings), which allow the basic mixing process, i.e., $\omega_s=\omega_p-\omega_i$, where $\omega_s$, $\omega_p$, and $\omega_i$ are the signal, the pump, and the idler frequencies, respectively, and efficiently suppress propagation of unwanted higher tones including $\omega_{2p}=2\omega_p$, $\omega_{p+s}=\omega_p +\omega_s$, $\omega_{p+i} = \omega_p + \omega_i$, etc. The engineered dispersion loadings allow achieving sufficiently wide $3$ dB-bandwidth from $3$ GHz to $9$ GHz combined with a reasonably small ripple ($\pm2$ dB) in the gain-versus-frequency dependence.