Search for PNC in atomic dysprosium

Results and current progress of a search for parity nonconservation (PNC) in a pair of nearly degenerate opposite parity states in atomic dysprosium are discussed. By observing time-resolved quantum beats between these sublevels, we look for interference between a Stark-induced amplitude and the much smaller PNC amplitude. We have reported elsewhere (A.-T. Nguyen, et al., Phys. Rev. A 56, 3453 (1997)) a value of |Hω| |2.3±2.9(statistical)±.7(systematic)| Hz for the magnitude of the weak interaction matrix element. In order to increase the statistical sensitivity in a new search, we will employ a cw scheme for excitation and detection. This involves utilizing cw lasers to populate the odd parity level via two intermediate states. We have measured various spectroscopic parameters of the intermediate states including branching ratios, lifetimes, isotope shifts, and hyperfine structure. Furthermore, we have modeled an efficient scheme for coherent population transfer using diverging cw Gaussian laser beams and adiabatic passage. This should increase statistical sensitivity to PNC effects by several orders of magnitude. (authors)