Efficient Sorting of Free Electron Orbital Angular Momentum

TL;DR

This paper introduces an electrostatic electron optical device that efficiently sorts electrons by their orbital angular momentum, enabling better analysis of electron wavefunctions in various scattering experiments.

Contribution

It presents a novel electrostatic method for parallel, efficient sorting of electron OAM states using charged needles and electrode arrays, inspired by modal transformation techniques.

Findings

Demonstrates that electrostatic elements can perform OAM sorting.

Enables analysis of inelastically scattered electron spatial modes.

Provides a practical device for electron OAM measurement.

Abstract

We propose a method for sorting electrons by orbital angular momentum (OAM). Several methods now exist to prepare electron wavefunctions in OAM states, but no technique has been developed for efficient, parallel measurement of pure and mixed electron OAM states. The proposed technique draws inspiration from the recent demonstration of the sorting of OAM through modal transformation. We show that the same transformation can be performed with electrostatic electron optical elements. Specifically, we show that a charged needle and an array of electrodes perform the transformation and phase correction necessary to sort orbital angular momentum states. This device may enable the analysis of the spatial mode distribution of inelastically scattered electrons.