title: Sub-dekahertz ultraviolet spectroscopy of 199Hg+
abstract: Using a laser that is frequency locked to a Fabry-Perot etalon of high finesse and stability, we probe the 5d(10)6s (2)S(1/2)(F = 0)<-->5d(9)6s(2) (2)D(5/2)(F = 2) Deltam(F) = 0 electric-quadrupole transition of a single laser-cooled 199Hg+ ion stored in a cryogenic radio-frequency ion trap. We observe Fourier-transform limited linewidths as narrow as 6.7 Hz at 282 nm ( 1.06x10(15) Hz), yielding a line Q approximately 1.6x10(14). We perform a preliminary measurement of the 5d(9)6s(2) (2)D(5/2) electric-quadrupole shift due to interaction with the static fields of the trap, and discuss the implications for future trapped-ion optical frequency standards.
authors.affiliation: National Institute of Standards and Technology, Boulder, Colorado 80303, USA.
authors.initials: RJ
authors.lastname: Rafac
authors.initials: BC
authors.lastname: Young
authors.initials: JA
authors.lastname: Beall
authors.initials: WM
authors.lastname: Itano
authors.initials: DJ
authors.lastname: Wineland
authors.initials: JC
authors.lastname: Bergquist