A Stern-Gerlach-like approach to electron orbital angular momentum measurement

TL;DR

This paper proposes a novel non-interferometric method for measuring electron orbital angular momentum using a spatially varying magnetic field, enabling analysis of scattered electrons' energy and angular momentum distributions.

Contribution

It introduces a new measurement device design based on angular momentum-dependent focusing, advancing the capability to analyze electron OAM states.

Findings

The method works for mixed, superposed, and pure states.

It allows simultaneous measurement of energy and orbital angular momentum distributions.

The approach is analogous to a Stern-Gerlach experiment for electrons.

Abstract

Many methods now exist to prepare free electrons into orbital angular momentum states, and the predicted applications of these electron states as probes of materials and scattering processes are numerous. The development of electron orbital angular momentum measurement techniques has lagged behind. We show that coupling between electron orbital angular momentum and a spatially varying magnetic field produces an angular momentum-dependent focusing effect. We propose a design for an orbital angular momentum measurement device built on this principle. As the method of measurement is non-interferometric, the device works equally well for mixed, superposed and pure final orbital angular momentum states. The energy and orbital angular momentum distributions of inelastically scattered electrons may be simultaneously measurable with this technique.