Spectroscopy of the fractional vortex eigenfrequency in a long Josephson 0-kappa junction

TL;DR

This paper investigates the eigenfrequency of fractional Josephson vortices in long Josephson junctions using microwave spectroscopy, revealing how their frequency depends on magnetic flux and bias current, and confirming theoretical models.

Contribution

It provides experimental measurements of fractional vortex eigenfrequencies and validates theoretical predictions about their dependence on flux and current.

Findings

Eigenfrequency depends on magnetic flux and bias current.

Experimental results agree with theoretical models.

Fractional vortices are pinned and have distinct oscillation properties.

Abstract

Fractional Josephson vortices carry a magnetic flux Phi, which is a fraction of the magnetic flux quantum Phi_0 ~ 2.07x10^{-15} Wb. Their properties are very different from the properties of the usual integer fluxons. In particular, fractional vortices are pinned and have an oscillation eigenfrequency which is expected to be within the Josephson plasma gap. Using microwave spectroscopy, we investigate the dependence of the eigenfrequency of a fractional Josephson vortex on its magnetic flux $\Phi$ and on the bias current. The experimental results are in good agreement with the theoretical predictions.