We numerically investigate the behavior of a Josephson traveling wave parametric amplifier assuming a current-phase relation with a second--harmonic contribution. We find that varying the weight of harmonic terms in the Josephson current affects the gain profile. The analysis of gain characteristics, phase-space portraits, Poincar\'e sections, and Fourier spectra demonstrates that the nonsinusoidal contribution influences the operating mode and stability of the device. In particular, we identify the optimal weighting of harmonic contributions that maximizes amplification, achieving gains up to ∼13dB in a device without dispersion engineering.
@article{arxiv.2502.00804,
title = {Effect of 2$^\text{nd}$ harmonic current--phase relation on a behavior of a Josephson Traveling Wave Parametric Amplifier},
author = {Claudio Guarcello and Carlo Barone and Giovanni Carapella and Giovanni Filatrella and Andrea Giachero and Sergio Pagano},
journal= {arXiv preprint arXiv:2502.00804},
year = {2025}
}