Current Density of Majorana Bound States

TL;DR

This paper explains the oscillatory current behavior of Majorana zero modes on a topological insulator surface, proposing it as a signature for their detection and relating it to the zitterbewegung effect.

Contribution

It introduces a model linking oscillatory motion of Majorana zero modes to their spatial separation, providing a potential experimental signature.

Findings

Oscillatory current depends on the distance between zero modes.

The frequency of oscillations can be tuned within observational resolution.

The oscillatory behavior is analogous to the zitterbewegung effect.

Abstract

It is known that a non-local complex fermion can be written in terms of two Majorana fermions. We exploit this fact to explain the system of two Majorana zero modes bound to a vortex and an anti-vortex, on the surface of a topological insulator in contact with an s-wave superconductor, as a non-local complex fermion. Although the current density of a single zero mode vanishes, by starting with a wave packet consisted of the positive and negative energy complex fermions, we specify that a time-dependent oscillatory motion emerges in the system. We also show that the amplitude and frequency of the oscillations depend on the relative distance of those two zero modes. Therefore, the observation of this oscillatory motion can be considered as a signature of the Majorana zero modes. Also, as the frequency of such an oscillatory motion depends on the distance between the two zero modes, it can be adjusted to bring this frequency within the resolution of observations. Furthermore, we indicate that the predicted oscillatory current is the reminiscent of the zitterbewegung effect.