An exacting transition probability measurement - a direct test of atomic many-body theories

TL;DR

This paper introduces a highly precise, systematic protocol for measuring atomic transition probabilities in hydrogenic atoms, demonstrated on barium ions, enabling rigorous tests of many-body theories and fundamental physics.

Contribution

It presents a novel measurement protocol for decay branching fractions with sub-0.5 ext{%} uncertainty, directly testing quantum many-body calculations in barium ions.

Findings

Achieved sub-0.5 ext{%} uncertainty in decay measurements

Provided the first direct test of many-body theories on barium ions

Protocol applicable to other hydrogenic atoms

Abstract

A new protocol for measuring the branching fraction of hydrogenic atoms with only statistically limited uncertainty is proposed and demonstrated for the decay of the P$_{3/2}$ level of the barium ion, with precision below $0.5\%$. Heavy hydrogenic atoms like the barium ion are test beds for fundamental physics such as atomic parity violation and they also hold the key to understanding nucleo-synthesis in stars. To draw definitive conclusion about possible physics beyond the standard model by measuring atomic parity violation in the barium ion it is necessary to measure the dipole transition probabilities of low-lying excited states with precision better than $1\%$. Furthermore, enhancing our understanding of the $\it{barium-puzzle}$ in barium stars requires branching fraction data for proper modelling of nucleo-synthesis. Our measurements are the first to provide a direct test of quantum many-body calculations on the barium ion with precision below one percent and more importantly with no known systematic uncertainties. The unique measurement protocol proposed here can be easily extended to any decay with more than two channels and hence paves the way for measuring the branching fractions of other hydrogenic atoms with no significant systematic uncertainties.