Coherence-enhanced optical determination of the $^{229}$Th isomeric transition

TL;DR

This paper presents a theoretical study on how coherent light affects thorium nuclei fluorescence in crystals, proposing a novel optical method to precisely determine the $^{229}$Th isomeric transition energy using nuclear forward scattering.

Contribution

It introduces a new scheme for measuring the $^{229}$Th isomeric transition energy through electromagnetically modified nuclear forward scattering involving two coupled fields.

Findings

Fluorescence exhibits characteristic intensity modulations in the forward direction.

The initial decay signal is significantly sped up due to coherent propagation effects.

A novel measurement scheme for the transition energy is proposed.

Abstract

The impact of coherent light propagation on the excitation and fluorescence of thorium nuclei in a crystal lattice environment is investigated theoretically. We find that in the forward direction the fluorescence signal exhibits characteristic intensity modulations dominated by an orders of magnitude faster, sped-up initial decay signal. This feature can be exploited for the optical determination of the isomeric transition energy. In order to obtain a unmistakable signature of the isomeric nuclear fluorescence, we put forward a novel scheme for the direct measurement of the transition energy via electromagnetically modified nuclear forward scattering involving two fields that couple three nuclear states.