Analysis of angular momentum properties of photons emitted in fundamental atomic processes

TL;DR

This paper introduces a theoretical method to analyze the angular momentum projection of photons emitted in atomic processes, providing insights into the role of angular momentum in fundamental atomic physics.

Contribution

A simple theoretical approach based on expectation values of angular momentum operators to determine photon angular momentum properties in atomic emissions.

Findings

Recombination photons carry non-zero orbital angular momentum projection.

Method applied successfully to plane-wave, spherical-wave, and Bessel light.

Provides new insights into angular momentum in atomic photon emissions.

Abstract

Many atomic processes result in the emission of photons. Analysis of the properties of emitted photons, such as energy and angular distribution as well as polarization, is regarded as a powerful tool for gaining more insight into the physics of corresponding processes. Another characteristic of light is the projection of its angular momentum upon propagation direction. This property has attracted a special attention over the last decades due to studies of twisted (or vortex) light beams. Measurements being sensitive to this projection may provide valuable information about the role of angular momentum in the fundamental atomic processes. Here we describe a simple theoretical method for determination of the angular momentum properties of the photons emitted in various atomic processes. This method is based on the evaluation of expectation value of the total angular momentum projection operator. To illustrate the method, we apply it to the text-book examples of plane-wave, spherical-wave, and Bessel light. Moreover, we investigate the projection of angular momentum for the photons emitted in the process of the radiative recombination with ionic targets. It is found that the recombination photons do carry a non-zero projection of the orbital angular momentum.