Spin-Statistic Selection Rules for Multi-Equal-Photon Transitions in Atoms: Extension of the Landau-Yang Theorem to Multiphoton Systems

TL;DR

This paper introduces spin-statistic selection rules (SSSR) for multi-equal-photon transitions in atoms, extending the Landau-Yang theorem, and suggests experimental tests for these photon exclusion principles.

Contribution

It extends the Landau-Yang theorem to atomic photon transitions, establishing new selection rules (SSSR) that restrict total angular momentum values for multi-photon systems.

Findings

SSSR-1: two identical photons can only have even total angular momentum J.

SSSR-2: three identical dipole photons can only have odd total angular momentum J=1,3.

SSSR-3: four identical dipole photons can only have even total angular momentum J=0,2,4.

Abstract

We establish the existence of spin-statistic selection rules (SSSR) for multi-equal-photon transitions in atomic systems. These selection rules are similar to those for systems of many equivalent electrons in atomic theory. The latter ones are the direct consequence of Pauli exclusion principle. In this sense the SSSR play the role of the exclusion principle for photons: they forbid some particular states for the photon systems. We established several SSSR for few-photon systems. 1) First rule (SSSR-1): two-equivalent photons involved in any atomic transition can have only even values of the total angular momentum J. This selection rule is an extension of the Landau-Yang theorem to the photons involved in atomic transitions. 2) second rule (SSSR-2): three equivalent dipole photons involved in any atomic transition can have only odd values of the total angular momentum J=1,3. 3) third rule (SSSR-3): four equivalent dipole photons involved in any atomic transition can have only even values of the total angular momentum J=0,2,4. We also suggest a method for a possible experimental test of these SSSR by means of laser experiments.