Precision Measurements of Ba$^+$ Properties

Single trapped barium ions continue to offer a wealth of information about atomic and nuclear structure, oscillator strengths, and polarizabilities. We report progress towards a series of precision measurements that will provide stringent tests of theorists' predictions of these various properties. The first of these is a measurement of the $6S_{1/2} \leftrightarrow 5D_{3/2}$ magnetic dipole transition moment (M1), using a frequency stabilized laser operating at 2051 nm.\footnote{S.R. Williams \emph{et al.}, PRA \textbf{88} 012515 (2013)} This measurement is of interest, as knowledge of M1 is necessary in a proposed measurement of atomic partity nonconservation (PNC).\footnote{E.N. Fortson, PRL \textbf{70} 2383 (1993)} The second is a radio-frequency (rf) spectroscopic measurement of the hyperfine structure of the $5D_{3/2}$, resulting in a measurement of the nuclear magnetic octupole moment of $^{137}$Ba$^+$. Finally, we have begun work on measuring the branching ratio of spontaneous decay from $5D_{5/2}$ to $6S_{1/2}$ and $5D_{3/2}$. The underlying theory and motivation behind these measurements will be presented, as well as experimental upgrades and recent results.