Precision measurement of the branching ratio in the 6P3/2 decay of BaII with a single trapped ion

TL;DR

This paper reports a highly precise measurement of the branching ratios from the 6P3/2 state of BaII using a single trapped ion, improving accuracy over previous measurements and enabling comparison with theoretical calculations.

Contribution

The study introduces a novel combination of femtosecond pulse Rabi rotation and long-train pulse decay measurements for absolute branching ratio determination in BaII.

Findings

Measured branching ratios with threefold improved precision.

Normalized relative decay strengths: 0.756, 0.0290, 0.215.

Results enable comparison with theoretical dipole matrix element calculations.

Abstract

We present a measurement of the branching ratios from the 6P3/2 state of BaII into all dipoleallowed decay channels (6S1/2, 5D3/2 and 5D5/2). Measurements were performed on single 138Ba+ ions in a linear Paul trap with a frequency-doubled mode-locked Ti:Sapphire laser resonant with the 6S1/2->6P3/2 transition at 455 nm by detection of electron shelving into the dark 5D5/2 state. By driving a pi Rabi rotation with a single femtosecond pulse, a absolute measurement of the branching ratio to 5D5/2 state was performed. Combined with a measurement of the relative decay rates into 5D3/2 and 5D5/2 states performed with long trains of highly attenuated 455 nm pulses, it allowed the extraction of the absolute ratios of the other two decays. Relative strengths normalized to unity are found to be 0.756+/-0.046, 0.0290+/-0.0015 and 0.215+/-0.0064 for 6S1/2, 5D3/2 and 5D5/2 respectively. This approximately constitutes a threefold improvement over the best previous measurements and is a sufficient level of precision to compare to calculated values for dipole matrix elements.