Superluminal Tachyonlike Excitations of Dirac Fermions in a Topological Insulator Junction

TL;DR

This paper predicts the existence of superluminal (tachyonic) Dirac fermion excitations at the junction of two topological insulators, marking the first potential observation of tachyons in an electronic system.

Contribution

It introduces a theoretical framework showing how tachyonic surface states can emerge in topological insulator junctions, a novel phenomenon in condensed matter physics.

Findings

Prediction of superluminal dispersion in surface states

First theoretical proposal of tachyons in electronic systems

Potential experimental signature in topological insulator junctions

Abstract

We have considered a system of two topological insulators and have determined the properties of the surface states at the junction. Here we report that these states, under certain conditions exhibit superluminous (tachyonic) dispersion of the Dirac fermions. Although superluminal excitations are known to exist in optical systems, this is the first demonstration of possible tachyonic excitations in a purely electronic system. The first ever signature of tachyons could therefore be found experimentally in a topological insulator junction.