Fundamentally fastest optical processes at the surface of a topological insulator

TL;DR

This paper predicts that strong optical pulses can rapidly populate surface states of topological insulators, creating interference patterns that reveal topological properties, measurable via TR-ARPES.

Contribution

It introduces a novel prediction of electron interference fringes on topological insulator surfaces induced by optical pulses, linking to their topological band structure.

Findings

Single optical oscillation populates surface conduction band

Chiral interference fringes encode topological information

Distinct behavior compared to graphene

Abstract

We predict that a single oscillation of a strong optical pulse can significantly populate the surface conduction band of a three-dimensional topological insulator, Bi2Se3. Both linearly- and circularly-polarized pulses generate chiral textures of interference fringes of population in the surface Brillouin zone. These fringes constitute a self-referenced electron hologram carrying information on the topology of the surface Bloch bands, in particular, on the effect of the warping term of the low-energy Hamiltonian. These electron-interference phenomena are in a sharp contrast to graphene where there are no chiral textures for a linearly-polarized pulse and no interference fringes for circularly-polarized pulse. These predicted reciprocal space electron-population textures can be measured experimentally by time resolved angle resolved photoelectron spectroscopy (TR-ARPES) to gain direct access to non-Abelian Berry curvature at topological insulator surfaces.