Selection Rules for Optical Vortex Absorption by Landau-quantized Electrons

Abstract

An optical vortex beam carries orbital angular momentum ℓ in addition to spin angular momentum σ. We demonstrate that a Landau-quantized two dimensional electron system absorbs the optical vortex beam through modified selection rules, reflecting two kinds of angular momenta. The lowest Landau level electron absorbs the optical vortex beams with σ = 1 (positive helicity) and ℓ = 0 or σ = −1 (negative helicity) and ℓ = 2 in the electric dipole transition. The induced electric currents survive only along the edge of the sample, due to cancellation of the bulk currents. Thus, the magnetization can be induced by only the edge current. It is shown that the induced orbital magnetization disappears when the dark ring of the beam coincides with the disk edge. This scheme may provide a helicity-dependent absorption using the optical vortex beam.

Modification of Selection Rules of Landau-Quantized Electron by Coupling with Obliquely Irradiated Optical Vortex Beams

“…These results are equivalent to the results shown in our previous paper. [30,42] V. CONCLUSIONS AND REMARKS…”

Optical flux pump in the quantum Hall regime

“…However, in the quantum Hall regime, wavefunctions can be extended to a length scale comparable to optical wavelengths [7][8][9][10][11][12], and the coherence is topologically protected against dephasing [10,13]. Consequently, multipole transitions become possible [14][15][16][17]. Specifically, if the optical field has an orbital angular momentum (OAM) [5,18], these transitions transfer angular momentum from photons to electrons, and an interesting interplay between topological properties of electrons and photons may be observed [19][20][21].…”

“…However, there has been no observation of coherent multipole interaction with quantum Hall states, to the best of our knowledge. In this context, disorder may play an important role, as it mixes eigenstates of angular momentum, but previous studies have largely ignored its effect [15][16][17].…”