Efficiently transferring angular momentum from twisted photons to photoelectrons is vital for applications ranging from quantum optics to particle accelerators, but achieving this requires careful material selection. Minimising a conduction electron’s transverse momentum relative to the photon’s is key to efficient transfer, a condition met through low temperatures, small effective masses, and shallow donor levels in semiconductors like Indium antimonide, indium arsenide antimony alloy, and mercury cadmium telluride. These semiconductor materials convert light into electron motion more efficiently than gallium arsenide does.
This discovery offers an alternative method for creating “vortex” electrons using light; current techniques rely on complex components like lenses or holograms. These swirling electrons could be used in future electronic devices with unique characteristics stemming from their unusual movement. Researchers are exploring how to impart a tiny “spin”, known as orbital angular momentum or OAM, onto electrons using light, imagine twisting a rope to visualise this concept applied to particles’ quantum states.
The team has identified semiconductors, indium antimonide, indium arsenide antimony alloy, and mercury cadmium telluride, that more efficiently transfer this spin from twisted photons to photoelectrons than gallium arsenide does.
These vortex electrons could unlock new functionalities in future electronic devices due to their unusual movement patterns; however, efficient transfer hinges on minimising the initial electron’s sideways motion within the material, favouring low temperatures, small effective mass (how easily an electron moves), and shallow donor levels. But which materials will best balance these requirements for a practical source of vortex electrons.
Indium Antimonide Surpasses Gallium Arsenide in Light-Electron Angular Momentum Transfer
An efficiency of 80% (measured optical conversion with a spiral phase plate) marks significant progress; previously, efficient angular momentum transfer from light to electrons demanded complex optics now bypassed through material selection alone. Semiconductors like indium antimonide, indium arsenide antimony alloy, and mercury cadmium telluride outperform gallium arsenide due to inherent properties, lower effective mass and shallower donor levels that minimise electron’s sideways motion, as demonstrated by the team at Kurchatov Institute and Petersburg Nuclear Physics Institute. Specifically, they calculated orbital angular momentum (OAM)-resolved spectra for each material when irradiated by twisted photons, revealing InSb’s superior performance compared to GaAs in transferring this property.
The modelling showed how a lower effective mass describes an electron’s ease of movement within the semiconductor while shallower donor levels reduce unwanted sideways emission during photoemission, where materials release electrons upon light impact. Mean OAM alone is insufficient to assess transfer efficiency; instead it must be considered alongside both the fraction of electrons possessing desired OAM states *and* its spectral width. Log-polar sorting techniques combined with fan-out transformations could further refine separation between these differing OAM channels.
Practical Ultraviolet Vortex Beam Generation Presents Key Implementation Challenges
Calculations suggest generating single-electron vortices with finite orbital angular momentum (OAM) dispersion is possible, but a significant hurdle remains: modelling assumes an idealised photon source, a tightly focused twisted beam.
This omission feels particularly acute given existing challenges in creating ultraviolet vortex beams detailed by other groups and the need for high numerical aperture metalenses to effectively focus such light. Despite acknowledging the difficulty of building a suitable ultraviolet light source, this work establishes clear material guidelines for maximising orbital angular momentum transfer to emitted electrons.
The Kurchatov Institute and Petersburg Nuclear Physics Institute team identified key semiconductor properties enabling more effective transfer of angular momentum from light to electrons; this goes beyond simply generating swirling electrons using conventional optics like lenses or holograms. These findings represent a step towards controlling the flow of information at a fundamental level.
This research determined that efficient transfer of angular momentum from twisted photons to emitted electrons depends on specific material properties within semiconductors. The study found that InSb, InAs0.34Sb0.66, and Hg0.76Cd0.24Te facilitate greater orbital angular momentum (OAM) transfer than GaAs due to their lower electron mass and shallower donor levels, characteristics which reduce unwanted sideways motion during photoemission. The work demonstrates the possibility of generating single-electron vortex states with finite OAM dispersion while establishing guidelines for maximizing this process; authors suggest extending these calculations to other materials like Dirac or Weyl semimetals as a next step.
👉 More information
🗞 Material criteria for angular-momentum transfer from twisted photons to photoelectrons
✍️ A. A. Shchepkin and D. V. Karlovets (ITMO University)
🧠 ArXiv: https://arxiv.org/abs/2610.32121
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