title: Constraining the evolution of the fundamental constants with a solid-state optical frequency reference based on the 229Th nucleus.
abstract: We describe a novel approach to directly measure the energy of the narrow, low-lying isomeric state in 229Th. Since nuclear transitions are far less sensitive to environmental conditions than atomic transitions, we argue that the 229Th optical nuclear transition may be driven inside a host crystal with a high transition Q. This technique might also allow for the construction of a solid-state optical frequency reference that surpasses the short-term stability of current optical clocks, as well as improved limits on the variability of fundamental constants. Based on analysis of the crystal lattice environment, we argue that a precision (short-term stability) of 3×10(-17)<Δf/f<1×10(-15) after 1 s of photon collection may be achieved with a systematic-limited accuracy (long-term stability) of Δf/f∼2×10(-16). Improvement by 10(2)-10(3) of the constraints on the variability of several important fundamental constants also appears possible.
authors.affiliation: Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA.
authors.forename: Wade G
authors.initials: WG
authors.lastname: Rellergert
authors.forename: D
authors.initials: D
authors.lastname: DeMille
authors.forename: R R
authors.initials: RR
authors.lastname: Greco
authors.forename: M P
authors.initials: MP
authors.lastname: Hehlen
authors.forename: J R
authors.initials: JR
authors.lastname: Torgerson
authors.forename: Eric R
authors.initials: ER
authors.lastname: Hudson