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Physics

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Displaying 2026 - 2050 of 2493

Long-term comparison of caesium fountain primary frequency standards

December 7, 2009
Author(s)
Thomas E. Parker
There are currently nine caesium fountain primary frequency standards regularly reporting calibrations of International Atomic Time to the Bureau International des Poids et Measures (BIPM). An investigation has been carried out using data from the BIPM

Extension of the resonance line series of Mg III

December 1, 2009
Author(s)
C M. Brown, Alexander Kramida, Uri Feldman, Joseph Reader
Spectra of Mg emitted by a Penning discharge were recorded in the extreme ultraviolet (EUV) on a 10.7-m grazing-incidence spectrograph with phosphor image plates. The spectra provided nine new lines of Mg III between 156 and 166 Å and allowed us to improve

Ultra-Sensitive Optical Measurements of High-J Transitions in the O2 A-band

November 24, 2009
Author(s)
Daniel K. Havey, Joseph T. Hodges, David A. Long, Mitchio Okumura, Charles E. Miller
We report frequency-stabilized cavity ring-down spectroscopy measurements of high-J O2 A-band magnetic dipole line parameters. Our goals were to measure intensities and line shape parameters for the primary isotopologue of O2 in the A-band region and to

Limits on GPS Carrier Phase Time Transfer

November 16, 2009
Author(s)
Marc A. Weiss
The stability of differential delays between Global Navigation Satellite receivers is critical for time and frequency transfer. We study the limit of this transfer between two specific receivers from the study of data taken from these receivers while they

Novel, All-Digital Phase Measurement System for Time Scales

November 16, 2009
Author(s)
Stefania Romisch, Thomas E. Parker, Steven R. Jefferts
A novel, all-digital phase measurement system, to be utilized as part of the NIST Time Scale at NIST in Boulder, CO is presented. The system is used to compare output signals from several commercial atomic frequency standards: the phase differences between

Phase-lock Loops in Vibration Environments

November 16, 2009
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
A popular scheme for achieving low phase noise across a large range of offset frequencies is to employ an oscillator at an output frequency with low far-from-carrier noise that is phase-locked to a reference that has low close-to-carrier noise. We

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

Two-Way Satellite Time and Frequency Transfer Using 1 MChip/S codes

November 16, 2009
Author(s)
Victor S. Zhang, Thomas E. Parker, Demetrios Matsakis, Joseph Achkar, Daniele Rovera, Dirk Piester, Andreas Bauch, Luca Lorini
The Ku-band transatlantic and Europe to Europe two-way satellite time and frequency transfer (TWSTFT) operations used the 2.5 MChip/s pseudo-random codes with 3.5 MHz bandwidth until the end of July, 2009. The cost of TWSTFT operation is associated with

Realization of a programmable two-qubit quantum processor

November 15, 2009
Author(s)
David Hanneke, Jonathan Home, John D. Jost, Jason Amini, Dietrich G. Leibfried, David J. Wineland
The universal quantum computer is a device that could simulate any physical system and represents a major goal for the field of quantum information science. Algorithms performed on such a device are predicted to offer significant gains for some important

Optical frequency stabilization of a 10 GHz Ti:sapphire frequency comb by saturated absorption spectroscopy in 87Rubidium

November 4, 2009
Author(s)
Dirk Heinecke, Albrecht Bartels, Tara M. Fortier, Danielle Braje, Leo Hollberg, Scott A. Diddams
The high power per mode of a recently-developed 10 GHz femtosecond Ti:sapphire frequency comb permits nonlinear Doppler-free saturation spectroscopy in 87Rubidium with a single mode of the comb. We use this access to the natural linewidth of the Rubidium

Preparation of Dicke States in an Ion Chain

November 2, 2009
Author(s)
David Hume, Chin-Wen Chou, Till P. Rosenband, David J. Wineland
We have investigated theoretically and experimentally a method for preparing Dicke states in trapped atomic ions. We consider a linear chain of N ion qubits that is prepared in a particular Fock state of motion, jmi. The m phonons are removed by applying a

A Novel Wafer-plane Dosimeter for EUV Lithography

November 1, 2009
Author(s)
Steven E. Grantham, Charles S. Tarrio
Extreme Ultraviolet Lithography (EUVL) incorporates 13.5 nm light for patterning wafers and requires in-situ wafer-plane dosimetry that can be tailored to the requirements of an EUVL stepper’s environment. There are several types of detectors that are

10-GHz Self-Referenced Optical Frequency Comb

October 30, 2009
Author(s)
Albrecht Bartels, Dirk Heinecke, Scott Diddams
For a decade the femtosecond laser based frequency comb has played a key role in high precision optical frequency metrology.While often referred to as a precise optical frequency ruler, its tick marks are in fact too densely spaced for direct observation

Quantum walk on a line for a trapped ion

October 30, 2009
Author(s)
Peng Xue, Barry Sanders, Dietrich Leibfried
We show how a quantum walk can be experimentally realized for a single trapped ion and how to interpolate between the quantum and random walk by randomizing the phase of a generalized Hadamard coin flip. The signature of the quantum walk is manifested not

Effect of Surface Modes on Photon Propagation through Dielectric Bandgaps

October 28, 2009
Author(s)
Natalia Malkova, Sergey V. Polyakov, Alan L. Migdall, Garnett W. Bryant
We investigate the Hartman saturation effect of photons traveling through barriers created by bandgaps of multilayer stacks. In particular, we investigate theoretically the recently observed jumps in photon transversal times due to adding a single layer

Scalable arrays of doped silicon RF Paul traps

October 26, 2009
Author(s)
Joseph W. Britton, Dietrich G. Leibfried, James A. Beall, Brad R. Blakestad, Janus H. Wesenberg, David J. Wineland
We report techniques for the fabrication of multi-zone linear RF Paul traps which exploit the machinability and electrical conductivity of bulk doped silicon. The approach was verified by trapping and Doppler cooling 24Mg+ ions in two trap geometries: a

Uncooled, Millimeter-Scale Atomic Magnetometers with Femtotesla Sensitivity

October 26, 2009
Author(s)
John E. Kitching, Svenja A. Knappe, William C. Griffith, Jan Preusser, V Gerginov, Peter D. Schwindt, Vishal Shah, Ricardo Jimenez Martinez
We summarize recent results at NIST to develop high-performance yet highly miniaturized magnetic sensors based on atomic vapors confined in microfabricated alkali vapor cells. These sensors currently achieve sensitivities in the range of a few tens of

Development of an infrared optical scattering instrument from 1 um to 5 um

October 1, 2009
Author(s)
Jinan Zeng, Leonard M. Hanssen
The wavelength coverage of the IR optical scattering instrument developed at the National Institute of Standards and Technology has been extended to cover the continuous range from 1 um to 5 um. Besides the previously available diode lasers at wavelengths

Submillimeter Spectrum and Analysis of Vibrational and Hyperfine Coupling Effects in (HI)2

October 1, 2009
Author(s)
Laurent H. Coudert, Sergei P. Belov, F. Willaert, B. McElmurry, R. Lucchese, John W. Bevan, Jon T. Hougen
Observed rotational-vibrational transitions of HI dimer in the geared bending mode, centered at 511.9 GHz, are reported. This 50 kHz high resolution spectrum was recorded using a co-axially configured pulsed jet submillimeter spectrometer and the hyperfine
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