This book presents several precision measurements performed on atomic cesium and related to ongoing efforts toward a new measurement of the Weinberg mixing angle Q_W at low momentum transfer. The ultimate goal of this research program is an improved measurement of the extremely weak electric-dipole transition moment E_pv of the 6s ²S_1/2 → 7s ²S_1/2 transition of cesium, which is strictly electric-dipole forbidden without the weak force. Due to state mixing by the weak interaction, however, the optical transition is allowed, albeit very weakly, 10⁻¹¹ea₀. The magnitude of E_pv yields the weak mixing angle Q_W and improving the precision of Q_W provides a direct test of the standard model of particle physics. The three specific measurements described in this thesis are: hyperfine coupling constants of several states; the static Stark polarizability of the 7s ²S_1/2 state; and the ratio of the scalar to vector transition polarizabilities for the 6s → 7s transition. In addition, it describes a new optical phase locking technique developed by the author to allow interference measurements on any of the hyperfine components of the 6s → 7s transition. This technique is instrumental in a future measurement of E_pv /β.

Jonah Quirk is a recent graduate of Purdue University where his research focused on precision measurements supporting studies of atomic parity violation. His work has been published in several articles within Physical Review A and Physical Review Letters. Jonah received a Ph.D. and M.Sc. in Physics from Purdue University in 2025 and 2021, respectively. He also received a B.S. in Physics from the University of Southern Indiana. In his spare time, Jonah enjoys looking for and photographing birds.