Classification of Weyl point trajectories in multi-terminal Josephson junctions

Abstract

Topological protection is an attractive signature in both fundamental and applied researches because it provides an exotic and robust state. Multi-terminal Josephson junctions have recently been studied extensively owing to the emergence of topologically protected Weyl points without the need for topological materials. In this study, we examine the dynamic properties of Weyl points in multi-terminal Josephson junctions. The junctions are modulated by external parameters, such as electric gate voltage, magnetic flux, bias voltage. The Weyl points are manipulated and draw trajectories accompanied by pair creation and annihilation. The trajectories form both closed loops and open lines. We classify these trajectories using the Chern number and the phase diagram.