title: Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance.
abstract: We report tests of local position invariance and the variation of fundamental constants from measurements of the frequency ratio of the 282-nm 199Hg+ optical clock transition to the ground state hyperfine splitting in 133Cs. Analysis of the frequency ratio of the two clocks, extending over 6 yr at NIST, is used to place a limit on its fractional variation of <5.8x10(-6) per change in normalized solar gravitational potential. The same frequency ratio is also used to obtain 20-fold improvement over previous limits on the fractional variation of the fine structure constant of |alpha/alpha|<1.3x10(-16) yr-1, assuming invariance of other fundamental constants. Comparisons of our results with those previously reported for the absolute optical frequency measurements in H and 171Yb+ vs other 133Cs standards yield a coupled constraint of -1.5x10(-15)<alpha/alpha<0.4x10(-15) yr-1 and -2.7x10(-15)<d/dtlnmicroCs/microB<8.6x10(-15) yr-1.
authors.affiliation: P-23 Physics Division MS H803, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: T M
authors.initials: TM
authors.lastname: Fortier
authors.forename: N
authors.initials: N
authors.lastname: Ashby
authors.forename: J C
authors.initials: JC
authors.lastname: Bergquist
authors.forename: M J
authors.initials: MJ
authors.lastname: Delaney
authors.forename: S A
authors.initials: SA
authors.lastname: Diddams
authors.forename: T P
authors.initials: TP
authors.lastname: Heavner
authors.forename: L
authors.initials: L
authors.lastname: Hollberg
authors.forename: W M
authors.initials: WM
authors.lastname: Itano
authors.forename: S R
authors.initials: SR
authors.lastname: Jefferts
authors.forename: K
authors.initials: K
authors.lastname: Kim
authors.forename: F
authors.initials: F
authors.lastname: Levi
authors.forename: L
authors.initials: L
authors.lastname: Lorini
authors.forename: W H
authors.initials: WH
authors.lastname: Oskay
authors.forename: T E
authors.initials: TE
authors.lastname: Parker
authors.forename: J
authors.initials: J
authors.lastname: Shirley
authors.forename: J E
authors.initials: JE
authors.lastname: Stalnaker