Precision measurement of branching fractions of $^{138}$Ba$^{+}$: Testing many body theories below one percent level

TL;DR

This paper reports a highly precise measurement of the branching fractions of the $^{138}$Ba$^{+}$ ion's excited state, enabling accurate determination of dipole matrix elements crucial for parity non-conservation studies.

Contribution

It provides the first sub-one-percent level measurements of dipole matrix elements in barium ions, facilitating stringent tests of many-body theories relevant to fundamental physics.

Findings

Dipole matrix elements for $S-P$ and $P-D$ transitions measured as 3.306±0.014 and 3.036±0.016.

Measurement precision of 0.05% in branching fractions achieved.

Results enable direct comparison with theoretical calculations for parity violation experiments.

Abstract

The branching fractions from the excited state $6P_{1/2}$ of singly charged barium ion has been measured with a precision $0.05%$ in an ion trap experiment. This measurement along with the known value of the upper state life-time allowed the determination of the dipole matrix elements for the transitions $P-S$ and $P-D$ to below one percent level. Therefore, for the first time it is now possible to compare the many body calculations of these matrix elements at level which is of significance to any parity non-conservation experiment on barium ion. Moreover, these dipole matrix elements are the most significant contributors to the parity violating matrix element between the $S-D$ transition, contributing upto $90%$ to the total. Our results on the dipole matrix elements are $3.306\pm0.014$ and $3.036\pm0.016$ for the $S-P$ and $P-D$ transitions respectively.