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Search Publications by: Tara Fortier (Fed)

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Displaying 51 - 75 of 89

Improved signal-to-noise ratio of 10 GHz microwave signals generated with a mode-filtered femtosecond laser frequency comb

February 18, 2009
Author(s)
Scott A. Diddams, Matthew S. Kirchner, Tara M. Fortier, Danielle Braje, A. M. Weiner, Leo W. Hollberg
We use a Fabry-Perot cavity to optically filter the output of a Ti:sapphire frequency comb to integer multiples of the original 1 GHz mode spacing. This effectively increases the pulse repetition rate which is useful for several applications. In the case

Yb Optical Lattice Clock

November 23, 2008
Author(s)
Nathan D. Lemke, Andrew Ludlow, Zeb Barber, N Poli, C.W. Hoyt, Long-Sheng Ma, Jason Stalnaker, Christopher W. Oates, Leo Hollberg, James C. Bergquist, A. Brusch, Tara Fortier, Scott Diddams, Thomas P. Heavner, Steven R. Jefferts, Tom Parker
We describe the development and latest results of an optical lattice clock based on neutral Yb atoms, including investigations based on both even and odd isotopes. We report a fractional frequency uncertainty below 10 -15 for 171Yb.

Alpha-Dot or Not: Comparison of Two Single Atom Optical Clocks

October 5, 2008
Author(s)
Till P. Rosenband, David Hume, Chin-Wen Chou, J.C. Koelemeij, A. Brusch, Sarah Bickman, Windell Oskay, Tara M. Fortier, Jason Stalnaker, Scott A. Diddams, Nathan R. Newbury, William C. Swann, Wayne M. Itano, David J. Wineland, James C. Bergquist
Repeated measurements of the frequency ratio of Hg + and Al + single-atom optical clocks over the course of a year yield a constraint on the possible temporal variation of the fine-structure constant a. The time variation of the measured ratio corresponds

Recent atomic clock comparisions at NIST

October 1, 2008
Author(s)
Luca Lorini, Neil Ashby, Anders Brusch, Scott Diddams, Robert E. Drullinger, Eric Eason, Tara Fortier, Pat Hastings, Thomas P. Heavner, David Hume, Wayne M. Itano, Steven R. Jefferts, Nathan R. Newbury, Tom Parker, Till P. Rosenband, Jason Stalnaker, William C. Swann, David J. Wineland, James C. Bergquist
The record of atomic clock frequency comparisons at NIST over the past half-decade provides one of the tightest constraints of any present-day, temporal variations of the fundamental constants. Notably, the 6-year record of increasingly precise

Ratio of the Al + and Hg + Optical Clock Frequencies to 17 Decimal Places

August 25, 2008
Author(s)
Wayne M. Itano, Till P. Rosenband, David Hume, P.O. Schmidt, Chin-Wen Chou, A. Brusch, Luca Lorini, Windell Oskay, Robert E. Drullinger, Sarah Bickman, Tara M. Fortier, Jason Stalnaker, Scott A. Diddams, William C. Swann, Nathan R. Newbury, David J. Wineland, James C. Bergquist
Frequency standards (atomic clocks) based on narrow optical transitions in 27Al + and 199Hg + have been developed over the past several years at NIST. These two types of standards are both based on single ions confined in Paul traps, but differ in the

Astronomical spectrograph calibration with broad-spectrum frequency combs

May 29, 2008
Author(s)
Danielle Braje, Matthew S. Kirchner, Tara M. Fortier, Scott A. Diddams, Leo W. Hollberg, Steve Osterman
Broad-band frequency combs are filtered to spectrographically resolvable frequency-mode spacing, and the limitations of using cavities for spectral filtering are considered. Data and theory are used to show implications to spectrographic calibration of

Frequency evaluation of the doubly forbidden 1 S 0 - 3 P 0 transition in bosonic 174 Yb

May 6, 2008
Author(s)
Nicola Poli, Zeb Barber, Nathan D. Lemke, Christopher W. Oates, Tara Fortier, Scott Diddams, Leo W. Hollberg, James C. Bergquist, Anders Brusch, Steven R. Jefferts, Thomas P. Heavner, Tom Parker
We report an uncertainty evaluation of an optical lattice clock based on the 1S 0 – 3P 0 transition in the bosonic isotope 174Yb using magnetically induced spectroscopy. The uncertainty due to systematic effects has been reduced to less than 0.8Hz, which

Sr Lattice Clock at 1 x 10 -16 Fractional Uncertainty by Remote Optical Evaluation with a Ca clock

March 28, 2008
Author(s)
A D. Ludlow, T Zelevinsky, G K. Campbell, S Blatt, M M. Boyd, M de Miranda, M J. Martin, S M. Foreman, J Ye, Tara M. Fortier, Jason Stalnaker, Scott A. Diddams, Yann LeCoq, Zeb Barber, Nicola Poli, Nathan D. Lemke, K. Beck, Christopher W. Oates
Optical atomic clocks promise timekeeping at the highest precision and accuracy, owing to their high operating frequency. The most accurate optical clocks are presently based on single trapped ions1, due to the exquisite control possible over their

Optical Lattice Induced Light Shifts in a Yb Atomic Clock

March 14, 2008
Author(s)
Zeb Barber, Jason Stalnaker, Nathan D. Lemke, Christopher W. Oates, Tara M. Fortier, Scott A. Diddams, Leo W. Hollberg, C Hoyt
We present an experimental study of the lattice induced light shifts on the $^1S_0\rightarrow\,^3P_0$ clock transition of ytterbium. The ``magic'' frequency for the $^{174}$Yb isotope was determined to be $u_{magic} = 394\,799\,475(35)$MHz. The

Frequency ratio of Al + and Hg + single-ion optical clocks; metrology at the 17th decimal place

March 6, 2008
Author(s)
Till P. Rosenband, David Hume, P. O. Schmidt, Chin-Wen Chou, Anders Brusch, Luca Lorini, Windell Oskay, Robert E. Drullinger, Tara M. Fortier, Jason Stalnaker, Scott A. Diddams, Nathan R. Newbury, W Swann, Wayne M. Itano, David J. Wineland, James C. Bergquist
We report the frequency ratio of the two most accurate and stable atomic clocks with a total fractional uncertainty of 5.2 X 10 -17 . This frequency ratio is the best-known physical constant that is not a simple integer. Repeated measurements during the

Optical-to-microwave frequency comparison with fractional uncertainty of 10 -15

October 1, 2007
Author(s)
Jason Stalnaker, Scott A. Diddams, Tara M. Fortier, K Kim, Leo W. Hollberg, James C. Bergquist, Wayne M. Itano, Marie Delaney, Luca Lorini, Windell Oskay, Thomas P. Heavner, Steven R. Jefferts, Filippo Levi, Thomas E. Parker, Jon H. Shirley
We report the technical aspects of the optical-to-microwave comparison for our recent measurements of the optical frequency of the mercury single-ion frequency standard in terms of the SI second as realized by the NIST-F1 cesium fountain clock. Over the

Lattice-based optical clock using an even isotope of Yb

September 12, 2007
Author(s)
Zeb Barber, C Hoyt, Jason Stalnaker, Nathan D. Lemke, Christopher W. Oates, Tara M. Fortier, Scott A. Diddams, Leo W. Hollberg
We describe progress toward an optical lattice clock based on an even isotope of Yb. The 1S_0 - P_0 clock resonance in 174Yb is accessed using a magnetically induced spectroscopic technique. Using ~1 mT static magnetic fields and ~10 uW of probe light

Optical frequency standards based on mercury and aluminum ions

September 12, 2007
Author(s)
Wayne M. Itano, James C. Bergquist, Anders Brusch, Scott A. Diddams, Tara M. Fortier, Thomas P. Heavner, Leo W. Hollberg, David Hume, Steven R. Jefferts, Luca Lorini, Thomas E. Parker, Till P. Rosenband, Jason Stalnaker
Single-trapped-ion frequency standards based on a 282 nm transition in 199Hg+ and on a 267 nm transition in 27Al+ have been developed at NIST over the past several years. Their frequencies are measured relative to each other and to the NIST primary

Frequency Comparison of Al + and Hg + Optical Standards

June 24, 2007
Author(s)
Till P. Rosenband, David Hume, Anders Brusch, Luca Lorini, P. O. Schmidt, Tara M. Fortier, Jason Stalnaker, Scott A. Diddams, Nathan R. Newbury, W Swann, Windell Oskay, Wayne M. Itano, David J. Wineland, James C. Bergquist
We compare the frequencies of two single ion frequency standards: 27Al + and 199Hg +. Systematic fractional frequency uncertainties of both standards are below 10 -16, and the statistical measurement uncertainty is below 5 x 10 -17. Recent ratio

Observation of the 1 S 0 - 3 P 0 clock transition in 27 Al +

June 1, 2007
Author(s)
Till P. Rosenband, P. O. Schmidt, David Hume, Wayne M. Itano, Tara M. Fortier, Jason Stalnaker, Scott A. Diddams, Jeroen Koelemeij, James C. Bergquist, David J. Wineland
We report for the first time, laser spectroscopy of the 1S 0 – 3P 0 clock transition in 27Al +. A single aluminum ion and a single beryllium ion are simultaneously confined in a linear Paul trap, coupled by their mutual Coulomb repulsion. This coupling

Improved Limits on Variation of the Fine Structure Constant and Violation of Local Position Invariance

May 29, 2007
Author(s)
Tara M. Fortier, Neil Ashby, James C. Bergquist, Marie Delaney, Scott A. Diddams, Thomas P. Heavner, Leo W. Hollberg, Wayne M. Itano, Steven R. Jefferts, K Kim, Windell Oskay, Thomas E. Parker, Jon H. Shirley, Jason Stalnaker, Filippo Levi, Luca Lorini
We report tests of Local Position Invariance (LPI) and constancy 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

Stable Laser System for Probing the Clock Transition at 578 nm in Neutral Ytterbium

May 29, 2007
Author(s)
Christopher W. Oates, Zeb Barber, Jason Stalnaker, C Hoyt, Tara M. Fortier, Scott A. Diddams, Leo W. Hollberg
In this paper we describe a new laser system we have developed to probe the ultra-narrow 1S 0 -> 3P 0 clock transition at 578 nm in neutral ytterbium. The yellow light is produced by sum frequency generation in a periodically-poled waveguide. With

Absolute frequency measurement of the neutral 40 Ca optical frequency standard at 657 nm based on microkelvin atoms

March 14, 2007
Author(s)
G Wilpers, Christopher W. Oates, Scott A. Diddams, A Bartels, Tara M. Fortier, Windell Oskay, James C. Bergquist, Steven R. Jefferts, Thomas P. Heavner, Thomas E. Parker, Leo W. Hollberg
We report an absolute frequency measurement of the optical clock transition at 657 nm in 40Ca with a relative uncertainty of 7.5x10 -15, the most accurate frequency measurement of a neutral atom optical transition to date. Relative instabilities of 2x10

Precision Atomic Spectroscopy for Improved Limits on Variation of the Fine Structure Constant and Local Position Invariance

February 16, 2007
Author(s)
Tara M. Fortier, Jason Stalnaker, Scott A. Diddams, Neil Ashby, Luca Lorini, Windell Oskay, Marie Delaney, James C. Bergquist, Steven R. Jefferts, Thomas E. Parker, Thomas P. Heavner, Filippo Levi, Jon H. Shirley, Wayne M. Itano, Kyoungsik Kim, Leo W. Hollberg
We report tests of local position invariance (LPI) and the constancy of fundamental constants from measurements of the frequency ratio of the 282-nm $^{199}$Hg$^+$ optical clock transition to the ground state hyperfine splitting in $^{133}$Cs. Analysis of

Kilohertz-level spectroscopy of cold atoms with a femtosecond optical frequency comb

October 19, 2006
Author(s)
Tara Fortier, Yann Le Coq, Jason Stalnaker, Davi Ortega, Scott Diddams, Christopher W. Oates, Leo W. Hollberg
We have performed sub-Doppler spectroscopy on the narrow intercombination line of cold calcium atoms using the amplified output of a femtosecond laser frequency comb. Injection locking of a 657-nm diode laser with a femtosecond comb allowed for two regimes

A Low-Threshold Self-Referenced Ti:Sapphire Optical Frequency Comb

October 2, 2006
Author(s)
Matthew S. Kirchner, Tara M. Fortier, A Bartels, Scott A. Diddams
We demonstrate an octave-spanning, self-referenced optical frequency comb produced with a high repetition rate (frep=585 MHz) femtosecond Ti:Sapphire laser that requires less that 1 W of 532 nm pump power. The frequency comb was stabilized to a CW laser as

A single-atom optical clock with high accuracy

July 14, 2006
Author(s)
Windell Oskay, Scott A. Diddams, Elizabeth A. Donley, Tara M. Fortier, Thomas P. Heavner, Leo W. Hollberg, Wayne M. Itano, Steven R. Jefferts, M J. Jensen, Kyoungsik Kim, F Levi, Thomas E. Parker, James C. Bergquist
For the past fifty years, atomic frequency standards based on the cesium ground-state hyperfine splitting have been the most accurate timepieces in the world. One of the most accurate, current-generation, cesium standards is the NIST-F1 fountain, which has

Absolute Optical Frequency Measurements with a Fractional Uncertainty at 1 x 10 -15

June 5, 2006
Author(s)
Jason Stalnaker, Scott A. Diddams, Leo W. Hollberg, Kyoungsik Kim, Elizabeth A. Donley, Thomas P. Heavner, Steven R. Jefferts, Filippo Levi, Thomas E. Parker, James C. Bergquist, Wayne M. Itano, Marie J. Jensen, Luca Lorini, Windell Oskay, Tara M. Fortier, J Torgerson
We report the technical details specific to our recent measurements of the optical frequency of the mercury single-ion clock in terms of the SI second as realized by the NIST-F1 cesium fountain clock. In these measurements the total fractional uncertainty