Optical flux pump in the quantum Hall regime

TL;DR

This paper proposes an optical flux pump scheme in quantum Hall systems using light with orbital angular momentum to induce radial electron currents, demonstrating robustness against disorder and a unique power-law scaling.

Contribution

It introduces a novel optical method to manipulate quantum Hall systems, extending Laughlin's flux pumping concept to optical excitation in graphene.

Findings

Radial current is generated without electric bias.

Current is robust against disorder due to lattice symmetry.

Current scales with light intensity as a power law with exponent 2/3.

Abstract

A seminal gedankenexperiment by Laughlin describes the charge transport in quantum Hall systems via the pumping of flux. Here, we propose an optical scheme which probes and manipulates quantum Hall systems in a similar way: When light containing orbital angular momentum interacts with electronic Landau levels, it acts as a flux pump which radially moves the electrons through the sample. We investigate this effect for a graphene system with Corbino geometry, and calculate the radial current in the absence of any electric potential bias. Remarkably, the current is robust against the disorder which is consistent with the lattice symmetry, and in the weak excitation limit, the current shows a power-law scaling with intensity characterized by the novel exponent 2/3.