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Physics

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  • Published Date
Displaying 1851 - 1875 of 2493

Microwave quantum logic gates for trapped ions

August 11, 2011
Author(s)
Dietrich G. Leibfried, Christian Ospelkaus, Ulrich J. Warring, Yves Colombe, Kenton R. Brown, J. M. Amini, David J. Wineland
Achieving control over physical systems at the quantum level is a goal shared by scientific fields as diverse as metrology, information processing, simulation and chemistry. For trapped atomic ions, the quantized motional and internal degrees of freedom

Perpendicular ferromagnetic resonance measurements of damping and Lande g-factor in sputtered (Co 2 Mn) 1-x Ge x thin films

August 8, 2011
Author(s)
Thomas J. Silva, Hans T. Nembach, Justin M. Shaw, Michael Schneider, Matt Carey, Stefan Maat, Jeff Childress
X-ray diffraction (XRD), magnetometry, and ferromagnetic resonance (FMR) measurements were performed on sputtered thin films of the nominal Heusler alloy (Co 2Mn) 1-xGe x with varying Ge content and annealing temperature. XRD indicates some degree of L2 1

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.

Coordinating GPS Calibrations Among NIST, NRL, USNO, PTB, and OP

July 31, 2011
Author(s)
Marc A. Weiss, Victor S. Zhang, J White, K Senior, Demetrios Matsakis, S. Mitchell, P Uhrich, D Valat, W Lewandowski, G. Petit, Andreas Bauch, T. Feldman, A. Proia
Reviewing calibration results over the history since early 1980’s among several labs shows very mixed results. The best stabilities of receivers, as given by calibrations, are of the order of a few ns or better over a year, though many results are quite a

Improving the stability and accuracy of the Yb optical lattice clock

July 31, 2011
Author(s)
Andrew D. Ludlow, Yanyi Jiang, Nathan D. Lemke, Jeffrey A. Sherman, J. von Stecher, Richard W. Fox, Long-Sheng Ma, A.M. Rey, Christopher W. Oates
We report results for improving the stability and uncertainty of the NIST $^{171}$Yb lattice clock. The stability improvements derive from a significant reduction of the optical Dick effect, while the uncertainty improvements focus on improved

Limited Live-time Measurements of Frequency Spectra

July 31, 2011
Author(s)
David A. Howe, Neil Ashby, Danielle G. Lirette, Archita Hati, Craig W. Nelson
Frequency-difference-of-arrival (FDOA) can be used to monitor and track an emitter’s location by observing Doppler frequency shifts of the carrier during short pulsed transmissions. This specific application needs to consider two frequency-stability levels

MOT Loading Enhancement with Stimulated Light Forces

July 31, 2011
Author(s)
Elizabeth A. Donley, Tara C. Liebisch, Eric M. Blanshan, John E. Kitching
We demonstrate atom number enhancement in a magneto-optical trap (MOT) by use of bichromatic cooling to slow an atomic beam that is loaded into a MOT. Bichromatic cooling employs stimulated emission to apply strong cooling forces that are not limited by

Residual PM Noise Evaluation of Radio Frequency Mixers

July 31, 2011
Author(s)
Corey A. Barnes, Archita Hati, Craig W. Nelson, David A. Howe
Direct observation of phase modulated (PM) noise is often difficult due to the high dynamic range that exists between the carrier and the modulated sidebands. A common tool used to reduce the dynamic range is the phase detector, which removes the carrier

Status of a compact cold-atom CPT frequency standard

July 31, 2011
Author(s)
Elizabeth A. Donley, Francois-Xavier R. Esnault, John E. Kitching, Eugene N. Ivanov
We describe the main progress towards the realization of a cold atom frequency standard based on coherent population trapping (CPT). We explain our particular CPT configuration and give details on the experimental setup.

Synchronizing Computer Clocks Using Kalman Filters

July 31, 2011
Author(s)
Judah Levine
I have used the Kalman Filter algorithm to improve the link between the Internet Time Servers operated by the National Institute of Standards and Technology (NIST) and the primary atomic clock ensemble in Boulder, which realizes UTC(NIST) and which is used

Towards an all-digital time scale

July 31, 2011
Author(s)
Stefania Romisch, Steven R. Jefferts, Thomas E. Parker
The implementation of an all-digital time scale is under way at NIST, using a novel 8-channel, all-digital phase measurement system based on subsampling techniques. The phase measurement system is used to compare output signals from several commercial

Update on a Comparison of Cesium Fountain Primary Frequency Standards

July 31, 2011
Author(s)
Thomas E. Parker
An update to a previous long term frequency comparison of cesium fountain primary frequency standards has been made. This update covers the approximate three year interval from March 2008 to March 2011 and also includes two new standards. Also, simulated

Vibration Sensitivity of Optical Components: A Survey

July 31, 2011
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
We propose and demonstrate a novel technique to measure the vibration sensitivity of two-port fiber-based optical components. It uses a common-arm counter-propagating frequency-shifted interferometer that cancels the vibration induced phase noise of the

A circular dielectric grating for vertical extraction of single quantum dot emission

July 25, 2011
Author(s)
Marcelo I. Davanco, Matthew T. Rakher, Dieter Schuh, Antonio Badolato, Kartik A. Srinivasan
We demonstrate a suspended circular grating composed of partially etched annular trenches in a thin GaAs membrane, designed for e±cient and moderately broadband ( approx. 5 nm) extraction of emission from single InAs quantum dots. Simulations indicate that

Diamagnetic correction to the 9 Be + ground-state hyperfine constant

July 21, 2011
Author(s)
Nobuyasu Shiga, Wayne M. Itano, John J. Bollinger
We report an experimental determination of the diamagnetic correction to the 9Be + ground state hyperfine constant A. We measured A = −625 008 837.371(11) Hz at a magnetic field B of 4.4609 T. Comparison with previous results, obtained at lower values of B

Timing in Telecommunications Networks

July 20, 2011
Author(s)
Judah Levine
I describe the statistical considerations used to design systems whose clocks are compared using dial-up telephone lines or the Internet to exchange timing informaiton. The comparison is usually used to synchronize the time of a client system to the time

Normal modes of trapped ions in the presence of anharmonic trap potentials

July 19, 2011
Author(s)
Jonathan Home, David Hanneke, John D. Jost, Dietrich Leibfried, David J. Wineland
We theoretically and experimentally examine the effects of anharmonic terms in the trapping potential for linear chains of trapped ions. We concentrate on two different effects, which become significant at different levels of anharmonicity. The first is a

Dimensional Analysis of Through Silicon Vias Using the TSOM Method

July 12, 2011
Author(s)
Ravikiran Attota, Andrew Rudack
There is a great need for accurate, truly-3D metrology solutions that can be used for analysis of high aspect ratio features such as through-silicon-vias (TSVs). Through-focus scanning optical microscopy (TSOM) is an optical metrology method that provides
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