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Displaying 1 - 25 of 178

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