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Displaying 2201 - 2225 of 2503

Long-Term Frequency Instability of CPT Clocks With Microfabricated Vapor Cells

April 1, 2006
Author(s)
Vladislav Gerginov, Svenja A. Knappe, P Schwindt, V Shah, Leo W. Hollberg, John E. Kitching
We present an evaluation of the long-term frequency instability and environmental sensitivity of a chip-scale atomic clock based on coherent population trapping, particularly as affected by the light source subassembly. We find that the clock frequency is

Nonlinearity of high-power optical fiber power meters at 1480 nm

February 20, 2006
Author(s)
Igor Vayshenker, Shao Yang, Ralph Swafford
We describe a calibration system that measures the nonlinearity of optical fiber power meters (OFPMs) at a maximum power of 0.6 W and a minimum power of 0.2 mW at 1480 nm. The system is based on the triplet superposition method. This system measures the

Simple Spectral Stray Light Correction Method for Array Spectroradiometers

February 20, 2006
Author(s)
Yuqin Zong, Steven W. Brown, Bettye C. Johnson, Keith R. Lykke, Yoshihiro Ohno
In many applications, the measurement accuracy of spectroradiometers, particularly instruments with a single dispersive element, is limited by the presence of stray radiation within the instrument. A simple, practical method has been developed to correct a

Spontaneously grown GaN and AlGaN nanowires

January 1, 2006
Author(s)
Kristine A. Bertness, Alexana Roshko, Norman A. Sanford, Joy Barker, Albert Davydov
We have identified crystal growth conditions in gas-source molecular beam epitaxy (MBE) that lead to spontaneous formation of GaN nanowires with high aspect ratio on Si (1 1 1) substrates. The nanowires were oriented along the GaN c-axis and normal to the

Rotating-radio-frequency ion traps

October 20, 2005
Author(s)
T Hasegawa, John J. Bollinger
We propose a new ion trap, the rotating-rf trap, in which motion of a charged particle is described not by Mathieu-type functions but by trigonometric functions. In the rotating-rf trap, a quadrupole electric field confines charged particles, whereas in a

Surface-Electrode Architecture for Ion-Trap Quantum Information Processing

September 1, 2005
Author(s)
J Chiaverini, Brad R. Blakestad, Joseph W. Britton, John D. Jost, C. Langer, Dietrich G. Leibfried, R Ozeri, David J. Wineland
We investigate a surface-mounted electrode geometry for miniature linear radio frequency Paul ion traps. The electrodes reside in a single plane on a substrate, and the pseudopotential minimum of the trap is located above the substrate at a distance on

Thin-film coatings: Carbon nanotube coatings promise better thermal detectors

July 1, 2005
Author(s)
John H. Lehman, Anne Dillon
With high thermal conductivity and resistance to damage, carbon nanotube coatings are a promising new technology for thermal detectors. NIST and NREL scientists are exploring this viable alternative with the aim of developing better radiometric standards

A Polarizable Model for Ethylene Oxide

June 18, 2005
Author(s)
Raymond D. Mountain
A series of interaction models for ethylene oxide are developed for use in molecular simulation of the thermal properties of both the gas and liquid phases. While it is possible to develop nonpolarizable models to accurately generate either the gas or

Wavelength References for Optical Interferometry

June 12, 2005
Author(s)
Richard W. Fox, Leo W. Hollberg
We are exploring air wavelength references useful for interferometry. Femtosecond comb frequency measurements determine mode wavelengths of a stable optical cavity in vacuum, and subsequently a tunable laser is locked to the modes in air.

A Local Oscillator for Chip-Scale Atomic Clocks at NIST

June 1, 2005
Author(s)
Alan Brannon, J Breitbarth, Z Popovic, Vladislav Gerginov, V Shah, Svenja A. Knappe, Leo W. Hollberg, John E. Kitching
We report the first local oscillator (LO) demonstrating viability in terms of performance, size, and power, for chip scale atomic clocks (CSAC) at the National Institute of Standards and Technology in Boulder, CO. This volgate-controlled oscillator (VCO)

Low noise synthesis of microwave signals from an optical source

May 26, 2005
Author(s)
John J. McFerran, Eugene N. Ivanov, A Bartels, G Wilpers, Christopher W. Oates, Scott A. Diddams, Leo W. Hollberg
We demonstrate the low noise synthesis of a harmonic comb of microwave frequencies using a femtosecond laser based synthesiser that is referenced to a cabity-stabilised laser. The residual phase noise is ~ -110dBc/Hz at 1 Hz from the 10 GHz harmonic. An

Implementation of the semiclassical quantum Fourier transform in a scalable system

May 13, 2005
Author(s)
J Chiaverini, Joseph W. Britton, Dietrich G. Leibfried, Emanuel H. Knill, Murray D. Barrett, Brad R. Blakestad, Wayne M. Itano, John D. Jost, C. Langer, R Ozeri, Tobias Schaetz, David J. Wineland
One of the most interesting future applications of quantum computers is Shor's factoring algorithm, which provides an exponential speedup compared to known classical algorithms. The crucial final step in Shor's algorithm is the quantum Fourier transform

Optical frequency / wavelentgh references

April 25, 2005
Author(s)
Leo W. Hollberg, Christopher W. Oates, G Wilpers, C Hoyt, Zeb Barber, Scott A. Diddams, W Oskay, James C. Bergquist
Ideas for using visible light from atomic transitions for precision instrumentation and metrology go back at least to the 1800's. There are several good reasons to use optical frequencies, and with the scientific and technological advances of the last

International Comparisons of Femtosecond Laser Frequency Combs

April 1, 2005
Author(s)
Long-Sheng Ma, Zhiyi Bi, A Bartels, Lennart Robertsson, Massimo Zucco, Robert Windeler, G Wilpers, Christopher W. Oates, Leo W. Hollberg, Scott A. Diddams
Two types of international comparisons of femtosecond laser frequency combs have been performed in France and the USA. Five combs were involved in the comparisons. Three combs, of which two are transportable, employ nonlinear photonic crystal fiber (PCF)

An Atomic Clock on a Chip

February 1, 2005
Author(s)
John E. Kitching
This article described recent research in the Time and Frequency Division at NIST to develop highly miniaturized atomic frequency references using microfabrication technologies. We discuss the overall physics package design, fabrication of individual
Displaying 2201 - 2225 of 2503
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