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Displaying records 71 to 80 of 644 records.
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71. Ultra-low-noise Regenerative Frequency Divider for High Spectral Purity RF Signal Generation
Topic: Physics
Published: 5/24/2012
Authors: Archita Hati, Craig W Nelson, Corey A. Barnes, Danielle Grace Lirette, Jason Anthony DeSalvo, Tara Michele Fortier, Franklyn J Quinlan, Andrew D Ludlow, Till P Rosenband, Scott A Diddams, David Allan Howe
Abstract: We implement an ultra-low-noise frequency divider chain from 8 GHz to 5 MHz that utilizes custom-built regenerative frequency divide-by-2 circuits. The single-sideband (SSB) residual phase noise of this regenerative divider at 5 MHz output is -163 dB ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=911522

72. Vibrational analysis of stabilized lasers
Topic: Physics
Published: 5/24/2012
Authors: Kenneth Jeramiah Hughes, Archita Hati, Craig W Nelson, David Allan Howe
Abstract: Frequency-stabilized lasers are routinely used in a variety of research and application areas relating to laser-cooled atoms. Important applications in the cold-atom regime include atomic time keeping, inertial navigation, gravitational sensing, and ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=911603

73. High-power, hybrid Er:fiber/Tm:fiber frequency comb source in the 2 {mu}m wavelength region
Topic: Physics
Published: 5/1/2012
Authors: Florian B. (Florian) Adler, Scott A Diddams
Abstract: We present a 2-{mu}m frequency comb based on a reliable mode-locked Er:fiber laser with 100 MHz repetition rate. After shifting the spectrum of the amplified Er:fiber comb to longer wavelengths, a single-clad Tm/Ho:fiber is used as a self-pumped pre- ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=910655

74. Engineered two-dimensional Ising interactions on a trapped-ion quantum simulator with hundreds of spins
Topic: Physics
Published: 4/26/2012
Authors: Joseph Wright Britton, Brian C Sawyer, Adam Keith, C.-C. Joseph Wang, James K. Freericks, Hermann Uys, Michael Biercuk, John J Bollinger
Abstract: The presence of long-range quantum spin correlations underlies a variety of physical phenomena in condensed matter systems, potentially including high-temperature superconductivity, making this a fertile area for exploration. Unfortunately, many prop ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=910061

75. Automated Clock Comparisons and Time Scale Generation in the SIM Region
Topic: Physics
Published: 4/21/2012
Authors: Michael A Lombardi, J. Mauricio Lopez-Romero, Nelida Diaz-Munoz
Abstract: The second, the base unit of time interval in the International System, is defined in terms of the two hyperfine states of the Cesium atom ground energy level. This definition has so far served the metrology community well, and the uncertainty of th ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=909985

76. Magnetoencephalography with a chip-scale atomic magnetometer
Topic: Physics
Published: 4/17/2012
Authors: Svenja A Knappe, Tillman H. Sander, Jan Preusser, Rahul Ramdas Mhaskar, John E Kitching, Lutz Trahms
Abstract: We report on the measurement of somatosensory-evoked and spontaneous magnetoencephalography signals with a chip-scale atomic magnetometer. This uncooled, fiber-coupled sensor has a sensitive volume of 0.58 mm^u3^ inside a sensor head of volume 1 cm^u ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=910336

77. High-Accuracy Measurement of Atomic Polarizability in an Optical Lattice Clock
Topic: Physics
Published: 4/13/2012
Authors: Jeffrey Aaron Sherman, Nathan D. Lemke, Nathan Morris Bjork Hinkley, M. Pizzocaro, Richard W Fox, Andrew D Ludlow, Christopher W Oates
Abstract: Presently, the Stark effect contributes the largest source of uncertainty in a ytterbium optical atomic clock through blackbody radiation. By employing an ultracold, trapped atomic ensemble and high stability optical clock, we characterize the quadr ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=910796

78. The Evolution of Time Measurement Part V: Radio Controlled Clocks
Topic: Physics
Published: 4/1/2012
Author: Michael A Lombardi
Abstract: A historical article about the origins and the development of radio controlled clocks (Part IV of a IV-part series). It describes the first time signal radio stations, the early use of telegraphic time codes, and the modern use of digital time codes. ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=908252

79. Graphene Carrier Transport Theory
Topic: Physics
Published: 3/31/2012
Author: Shaffique Adam
Abstract: In this chapter we study the mechanisms for carrier transport in two dimensional graphene sheets. We demonstrate that at high carrier density, graphene's transport properties depend both on the type of impurities present and on graphene's screening ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=906994

80. Demonstration of on-sky calibration of astronomical spectra using a 20 GHz near-IR laser frequency comb
Topic: Physics
Published: 3/6/2012
Authors: Gabriel George Ycas, Franklyn J Quinlan, Scott A Diddams, Steve Osterman, Chad F. Bender, Brandon Botzer, Lawrence W. Ramsey , Ryan Terrien, Suvrath Mahadevan, Stephen Lewis Redman
Abstract: We describe and characterize a 25 GHz laser frequency comb based on a cavity-filtered erbium fiber mode-locked laser that provides a uniform array of optical frequencies stabilized using the GPS-system atomic clocks spanning 1475–1625 nm. This comb w ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=910016