On the neutron orbital angular momentum: Has it actually been demonstrated?

TL;DR

This paper critically examines a claimed demonstration of neutron orbital angular momentum, arguing that the interpretation is incorrect and that observed effects can be explained by standard neutron diffraction theory without invoking n-OAM.

Contribution

The paper refutes the previous claim of neutron orbital angular momentum detection, providing a theoretical analysis that aligns with experimental data without requiring n-OAM.

Findings

The interpretation of n-OAM in the previous experiment is incorrect.

Standard dynamical neutron diffraction theory explains the observed interferograms.

No additional neutron orbital angular momentum effect was observed.

Abstract

In a Nature LETTER [1], a control of neutron angular momentum was apparently demonstrated using a neutron crystal interferometer. In the meantime, a number of highly interesting articles have been published dealing with the n-OAM and neutron interferometry, citing [1]. We show that the interpretation of [1] having detected a n-OAM is incorrect for several serious reasons and point out inconsistencies. Based only on the theory of dynamical neutron diffraction, we calculate all the interferograms and show perfect agreement with those given in [1]. There was no need to assume an additional n-OAM because no additional effect was observed that could not be explained by standard theory.