Phys.org November 26, 2024
A fundamental requirement for quantum technologies is the ability to coherently control the interaction between electrons and photons. However, in many scenarios involving the interaction between light and matter, the exchange of linear or angular momentum between electrons and photons is not feasible, due to the dipole approximation limit. An international team of researchers (USA – University of Maryland, Italy, Spain, Germany, Japan, Australia) conceived a mechanism for such an orbital angular momentum transfer from optical vortex beams to electronic quantum Hall states. They identified a robust contribution to the radial photocurrent, in an annular graphene sample within the quantum Hall regime, that depended on the vorticity of light. The phenomenon could be interpreted as an optical pumping scheme, where the angular momentum of photons was transferred to electrons, generating a radial current, and the current direction was determined by the vorticity of the light. According to the researchers their findings offer fundamental insights into the optical probing and manipulation of quantum coherence… read more. TECHNICAL ARTICLE
Concept of OAM pumping. Credit: Nature Photonics, 26 November 2024