Parity violation in atomic ytterbium: Experimental sensitivity and systematics

We present a detailed description of the observation of parity violation in the ¹S₀-³D₁ 408-nm forbidden transition of ytterbium, a brief report of which appeared earlier. Linearly polarized 408-nm light interacts with Yb atoms in crossed E and B fields. The probability of the 408-nm transition contains a parity-violating term, proportional to $({E}·{}B)[(E×{}{E})·{}B]$, arising from interference between the parity-violating amplitude and the Stark amplitude due to the $E$ field (${E}$ is the electric field of the light). The transition probability is detected by measuring the population of the ${}³{P}₀$ state, to which $65%$ of the atoms excited to the ${}³{D}₁$ state spontaneously decay. The population of the ${}³{P}₀$ state is determined by resonantly exciting the atoms with 649-nm light to the $6s7s {}³{S}₁$ state and collecting the fluorescence resulting from its decay. Systematic corrections due to $E$-field and $B$-field imperfections are determined in auxiliary experiments. The statistical uncertainty is dominated by parasitic frequency excursions of the 408-nm excitation light due to the imperfect stabilization of the optical reference with respect to the atomic resonance. The present uncertainties are $9%$ statistical and $8%$ systematic. Methods of improving the accuracy for future experiments are discussed.