Branching ratio, transition frequency and lifetime measurements in $^{88}$Sr$^+$ with trapped ions

Precise measurements of atomic properties, such as branching ratios and transition frequencies and lifetimes, are important in the study of astrophysical objects as well as verification of relativistic many-body theories. We report on a new measurement of the branching ratio of the $5P_{1/2}$ and $5P_{3/2}$ states in $^{88}$Sr$^+$ to $10^{-4}$ fractional uncertainty, a $10^3$ times improvement over current results, using ions confined in a Paul trap. Using a fiber frequency comb and pulsed spectroscopy, we measure the absolute frequencies of the $5S_{1/2}-5P_{1/2}$ and $5S_{1/2}-5P_{3/2}$ transitions to within 200 kHz, previously only known to tens of MHz. By fitting the fluorescence curve of the ion with optical Bloch equations, we obtain a new measurement for the lifetime of the $5P_{1/2}$ and $5P_{3/2}$ states without using a pulsed laser source.