Far Infrared absorption of non center of mass modes and optical sum rule in a few electron quantum dot with Rashba spin-orbit coupling

TL;DR

This paper investigates how spin-orbit interaction affects far infrared absorption in quantum dots, revealing that absorption peaks follow the optical sum rule and can distinguish different spin-orbit coupling sources.

Contribution

It demonstrates that spin-orbit coupling enables coupling to non center of mass modes and shows how the optical sum rule can be used to infer electron number and differentiate spin-orbit sources.

Findings

Absorption peaks satisfy the optical sum rule.

Sum rule is insensitive to Rashba coupling strength with circular polarization.

The method can distinguish between different spin-orbit interaction sources.

Abstract

Spin-orbit interaction in a quantum dot couples far infrared radiation to non center of mass excitation modes, even for parabolic confinement and dipole approximation. The intensities of the absorption peaks satisfy the optical sum rule, giving direct information on the total number of electrons inside the dot. In the case of a circularly polarized radiation the sum rule is insensitive to the strength of a Rashba spin-orbit coupling due to an electric field orthogonal to the dot plane, but not to other sources of spin-orbit interaction, thus allowing to discriminate between the two.