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Search Publications by: Tom Heavner (Fed)

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Displaying 1 - 25 of 89

A Cold-Atom Beam Clock, based on Coherent Population Trapping

July 17, 2019
Author(s)
John D. Elgin, Thomas P. Heavner, John E. Kitching, Elizabeth A. Donley, Jayson Denney, Evan Salim
We present results from a novel atomic clock which employs a beam of cold 87 Rb atoms and spatially separated (Ramsey) coherent population trapping interrogation of the hyperfine clock transition at 6.834 GHz. The cold atomic beam is generated through the

Measurement of the Microwave Lensing Shift in NIST-F1 and NIST-F2

October 12, 2015
Author(s)
Steven R. Jefferts, Stephan E. Barlow, Thomas P. Heavner, Neil Ashby
We present measurements of the microwave lensing frequency shift in the Primary Frequency Standards (PFS) NIST-F1 and NIST-F2. This frequency bias is reasonably controversial with differing theories giving quite different results. Our measurements are in

Bias Corrections in Primary Frequency Standards

April 13, 2015
Author(s)
Thomas E. Parker, Thomas P. Heavner, Steven R. Jefferts
Primary frequency standards serve the function of calibrating the rate of International Atomic Time, TAI, and therefore play a critical role in the accuracy of the world's time. The Working Group on Primary and Secondary Frequency Standards, WGPSFS, is an

Broadband Rydberg Atom Based Self-Calibrating RF E-field Probe

August 16, 2014
Author(s)
Christopher L. Holloway, Joshua A. Gordon, Steven R. Jefferts, Thomas P. Heavner
We present a significantly new approach for an electric (E) field probe. The probe is based on the interaction of RF-fields with Rydberg atoms, where alkali atoms are excited optically to Rydberg states and the applied RF-field alters the resonant state of

First Accuracy Evaluation of NIST-F2

May 1, 2014
Author(s)
Thomas P. Heavner, Steven R. Jefferts, Jon H. Shirley, Thomas E. Parker, Elizabeth A. Donley, Neil Ashby, Stephan E. Barlow, Filippo Levi, Giovanni Costanzo
We report the first accuracy evaluation of NIST-F2, a second generation laser-cooled Cesium fountain primary standard developed at NIST with a cryogenic (Liquid Nitrogen) microwave cavity and flight region. The 80 K atom interrogation environment reduces

High-accuracy measurement of the black-body radiation frequency shift of the ground-state hyperfine transition in 133 Cs

February 7, 2014
Author(s)
Steven R. Jefferts, Thomas P. Heavner, Thomas E. Parker, Jon H. Shirley, Elizabeth A. Donley, Neil Ashby
We report a high-accuracy direct measurement of the blackbody radiation shift (BBR) of 133Cs ground state hyperfine transition. This frequency shift is one of the largest systematic frequency biases encountered in realizing the current definition of the SI

Polarization Enhanced Absorption Spectroscopy for Laser Stabilization"

November 15, 2013
Author(s)
Paul D. Kunz, Thomas P. Heavner, Steven R. Jefferts
We demonstrate a variation of pump-probe spectroscopy that is particularly useful for laser frequency stabilization. This polarization enhanced absorption spectroscopy (POLEAS) signal provides a significant improvement in signal-to-noise ratio over

Improvements to A Transportable Atomic Fountain Laser system

November 14, 2011
Author(s)
Paul D. Kunz, Vladislav Gerginov, Thomas P. Heavner, Steven R. Jefferts
We are developing a transportable rubidium (Rb) atomic fountain frequency standard which uses independently phase-locked diode lasers for laser-cooling. At this point in time, we have not demonstrated sub-Doppler (υKelvin) atom temperatures using out

A Laser-Cooled Frequency Standard for GPS

September 20, 2011
Author(s)
Thomas P. Heavner, Stephan E. Barlow, Marc A. Weiss, Neil Ashby, Steven R. Jefferts
NIST is in an initial phase of developing a prototype laser-cooled atomic frequency standard (AFS) for potential use in a future GPS system. The expected fractional frequency stability or Allan deviation, ς y(τ), will be 2x10 -13 at one second, improving

Comparing Room Temperature and Cryogenic Cesium Fountains

July 31, 2011
Author(s)
Steven R. Jefferts, Thomas P. Heavner, Thomas E. Parker, Jon H. Shirley, Elizabeth A. Donley, Filippo Levi, Davide Calonico, C Calosso, Giovanni Costanzo, B. Mongino
We have compared the frequency of a room temperature cesium fountain primary frequency standard with that of a cryogenic (~80K) cesium fountain. This comparison yields a measurement of the blackbody frequency shift of the room temperature fountain.

A Portable Rubidium Fountain

November 15, 2010
Author(s)
Paul D. Kunz, Steven R. Jefferts, Thomas P. Heavner
We are developing a transportable laser-cooled rubidium (Rb) atomic fountain frequency standard. Over the last year we have built the Ramsey cavity and rubidium source oven and are preparing to assemble the physics package. We have also made numerous

NIST F1 and F2

November 15, 2010
Author(s)
Thomas P. Heavner, Thomas E. Parker, Jon H. Shirley, Paul D. Kunz, Steven R. Jefferts
The National Institute of Standards and Technology operates a cesium fountain primary frequency standard, NIST-F1, which has been contributing to International Atomic Time (TAI) since 1999. During the intervening 11 years we have improved NIST-F1 so that

Quantum-Based SI Traceable Electric-Field Probe

July 25, 2010
Author(s)
Joshua A. Gordon, Christopher L. Holloway, Steven R. Jefferts, Thomas P. Heavner
We are presently investigating the feasibility of developing a technique that will allow direct traceable microwave electric field (E-field) measurements. The new approach is based on atomic rf-resonance spectroscopy, where an applied electrical field

Medium-Term Frequency Stability of Hydrogen Masers as Measured by a Cesium Fountain

June 2, 2010
Author(s)
Thomas E. Parker, Steven R. Jefferts, Thomas P. Heavner
Abstract Hydrogen masers are used extensively in time scale ensembles, but the frequency drift must be accurately known. NIST-F1, the cesium fountain primary frequency standard at the National Institute of Standards and Technology, now operates nearly

Progress on a Portable Rubidium Fountain Frequency Standard

November 16, 2009
Author(s)
Paul D. Kunz, Thomas P. Heavner, Steven R. Jefferts
We are developing a transportable laser-cooled rubidium (Rb) atomic fountain frequency standard. We have a complete optical package, and have recently shown cooled, launched, and detected atoms. Additionally, a new physics package has been designed and is

A Spin-1/2 Optical Lattice Clock

August 7, 2009
Author(s)
Nathan D. Lemke, Andrew D. Ludlow, Zeb Barber, Tara M. Fortier, Scott A. Diddams, Yanyi Jiang, Steven R. Jefferts, Thomas P. Heavner, Thomas E. Parker, Christopher W. Oates
We experimentally investigate an optical clock based on 171Yb (I = 1/2) atoms confined in an optical lattice. We have evaluated all known frequency shifts to the clock transition, including the density-dependent collision shift, with an uncertainty of 0.19

Frequency Measurements of Al+ and Hg+ Optical Standards

June 8, 2009
Author(s)
Wayne M. Itano, James C. Bergquist, Till P. Rosenband, David J. Wineland, David Hume, Chin-wen Chou, Steven R. Jefferts, Thomas P. Heavner, Tom Parker, Scott Diddams, Tara Fortier
Frequency standards based on narrow optical transitions in 27Al+ and 199Hg+ ions have been developed at NIST. Both standards have absolute reproducibilities of a few parts in 10 17. This is about an order of magnitude better than the fractional uncertainty

First Order Sideband Pulling in Atomic Frequency Standards

April 1, 2009
Author(s)
Jon H. Shirley, Thomas P. Heavner, Steven R. Jefferts
Many high performance atomic frequency standards, including cesium fountains and most optical standards, operate with pulsed measurements, that is, an atomic sample is prepared for measurement, the measurement is made, and the process is repeated at fixed

Progress on a portable rubidium fountain frequency standard

December 1, 2008
Author(s)
Paul D. Kunz, Thomas P. Heavner, Steven R. Jefferts
We are developing a simple and transportable laser-cooled rubidium (Rb) atomic fountain frequency standard. The optical package for this system uses DFB (distributed feedback) diode lasers and a frequency offset locking scheme to generate the optical

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.

NIST F1 and F2

October 5, 2008
Author(s)
Thomas P. Heavner, Tom Parker, Jon H. Shirley, Steven R. Jefferts
The National Institute of Standards and Technology operates a cesium fountain primary frequency standard, NIST-F1, which has been contributing to International Atomic Time (TAI) since 1999. At the time of the last Symposium on Frequency Standards and