title: Measurement of linear stark interference in 199Hg.
abstract: We present measurements of Stark interference in the (61)S(0)→6(3)P(1) transition in (199)Hg, a process whereby a static electric field E mixes magnetic dipole and electric quadrupole couplings into an electric dipole transition, leading to E-linear energy shifts similar to those produced by a permanent atomic electric dipole moment (EDM). The measured interference amplitude, a(SI) = (a(M1) + a(E2)) = (5.8 ± 1.5) × 10(-9) (kV / cm)(-1), agrees with relativistic, many-body predictions and confirms that earlier central-field estimates are a factor of 10 too large. More importantly, this study validates the capability of the (199)Hg EDM search apparatus to resolve nontrivial, controlled, and sub-nHz Larmor frequency shifts with EDM-like characteristics.
authors.affiliation: Department of Physics, Box 351560, University of Washington, Seattle, Washington 98195-1560, USA.
authors.forename: T H
authors.initials: TH
authors.lastname: Loftus
authors.forename: M D
authors.initials: MD
authors.lastname: Swallows
authors.forename: W C
authors.initials: WC
authors.lastname: Griffith
authors.forename: M V
authors.initials: MV
authors.lastname: Romalis
authors.forename: B R
authors.initials: BR
authors.lastname: Heckel
authors.forename: E N
authors.initials: EN
authors.lastname: Fortson