Effect of 2$^\text{nd}$ harmonic current--phase relation on a behavior of a Josephson Traveling Wave Parametric Amplifier

• DOI: 10.48550/arxiv.2502.00804
• Publication Date: 2025-01-01
• Authors: Guarcello, Claudio; Barone, Carlo; Carapella, Giovanni; Filatrella, Giovanni; Giachero, Andrea; Pagano, Sergio
• Keywords: Condensed Matter - Other Condensed Matter; Superconductivity (cond-mat.supr-con); Condensed Matter - Materials Science; Condensed Matter - Mesoscale and Nanoscale Physics; Condensed Matter - Superconductivity; Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences; Other Condensed Matter (cond-mat.other)

7 pages, 3 figures<br/>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, Poincaré 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 $\sim 13\;\text{dB}$ in a device without dispersion engineering.<br/>