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Physics

Time & frequency

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Displaying 126 - 150 of 167

SIM time scales

October 27, 2010
Author(s)
Michael A. Lombardi, J. Mauricio Lopez-Romero, Nelida Diaz-Munoz
This paper presents an analysis of the performance of some of the time scales generated in the Sistema Interamericano de Metrologia (SIM) region. We emphasize the generation of the first international time scale in near real time, the SIM Time scale (SIMT)

On-Board Signal Integrity for GPS

September 21, 2010
Author(s)
Marc A. Weiss, Pradipta Shome, Ron Beard
The elements of a space-based integrity approach are to monitor the signals on-board the satellite, such that signal performance can be maintained well within desired integrity limits. These elements include 1) a system for monitoring multiple atomic

The Development of a Unified Time and Frequency Program in the SIM Region

September 1, 2010
Author(s)
Michael A. Lombardi, J. Mauricio Lopez-Romero
The Sistema Interamericano de Metrologia (SIM) is one of five major regional metrology organizations (RMOs) recognized by the Bureau International des Poids et Mesures (BIPM). SIM is composed of the national metrology institutes (NMIs) located in the 34

yocto-Newton force detection sensitivity using trapped ions

August 22, 2010
Author(s)
Michael J. Biercuk, Joseph W. Britton, Hermann Uys, Aaron Vandevender, John Bollinger
Recent experimental advances have shown that it is possible to detect forces arising from electric fields at a level of aN/ √Hz (atto = 10 -18 through coupling of micro or nanofabricated mechanical resonators to a variety of physical systems including

Advances in Coherent Population Trapping for Atomic Clocks

August 10, 2010
Author(s)
John E. Kitching, Vishal Shah
We review advances in the field of coherent population trapping (CPT) over the last decade with respect to the application of this physical phenomenon to atomic frequency references. We provide an overview of both the basic phenomenon of coherent

A NIST Disciplined Oscillator

July 26, 2010
Author(s)
Michael A. Lombardi
The National Institute of Standards and Technology (NIST) now offers a service that provides customers with an oscillator locked to UTC(NIST), the United States national standard for frequency and time. A NIST disciplined oscillator (NISTDO) works by

Challenges in SIM to Create a Coordination Program for Time and Frequency

July 26, 2010
Author(s)
J. Mauricio Lopez-Romero, Michael A. Lombardi
The Sistema Interamericano de Metrologia (SIM), one of the world s five major regional metrology organizations (RMOs) recognized by the Bureau International des Poids et Mesures (BIPM), is comprised of national metrology institutes (NMIs) located in all 34

Hyper-Ramsey spectroscopy of optical clock transitions

July 22, 2010
Author(s)
Christopher W. Oates, V. I. Yudin, A. V. Taichenachev, Zeb Barber, Nathan D. Lemke, Andrew D. Ludlow, U Sterr, Ch. Lisdat, F Riehle
We present nonstandard optical Ramsey schemes that use pulses individually tailored in duration, phase and frequency to cancel spurious frequency shifts related to the excitation itself. In particular, the field shifts and their uncertainties can be

Efficient fiber optic detection of trapped ion flourescence

July 9, 2010
Author(s)
Aaron Vandevender, Yves Colombe, Jason Amini, Dietrich G. Leibfried, David J. Wineland
Integration of fiber optics may play a critical role in the development of quantum information processors based on trapped ions, atoms, and quantum dots. Fibers could help enable a scalable and efficient means of collecting light from and delivering light

High Spectral purity oscillator at 40 GHz: Design using air-dielectric Cavity

June 2, 2010
Author(s)
Archita Hati, Craig W. Nelson, Billy F. Riddle, David A. Howe
We describe the design of a low-PM noise 40 GHz oscillator that uses a conventional air-dielectric cavity resonator as a frequency discriminator to clean up the PM noise of a commercial 10 GHz dielectric resonator oscillator (DRO) multiplied by four. The

Low-Frequency Characterization of MEMS-Based Portable Atomic Magnetometer

June 2, 2010
Author(s)
Rahul R. Mhaskar, Svenja A. Knappe, John E. Kitching
Atomic magnetometers based on absorption or polarization rotation of light in an alkali vapor have recently demonstrated sensitivities rivaling those of superconducting quantum interference devices (SQUIDs). Miniaturization of such devices containing vapor

Medium-Term Frequency Stability of Hydrogen Masers as Measured by a Cesium Fountain

June 2, 2010
Author(s)
Thomas E. Parker, Steven R. Jefferts, Thomas P. Heavner
Abstract Hydrogen masers are used extensively in time scale ensembles, but the frequency drift must be accurately known. NIST-F1, the cesium fountain primary frequency standard at the National Institute of Standards and Technology, now operates nearly

Phase noise suppression in frequency comb generators

June 2, 2010
Author(s)
Craig W. Nelson, Archita Hati, J F. Nava-garcia, David A. Howe
We propose an idea to suppress the flicker (1/f) noise in radio frequency (RF) multiplier based frequency comb generators. Comb generators are often used for frequency multiplication in frequency synthesis. In general, comb generators apply high power to a

A common-view disciplined oscillator

May 24, 2010
Author(s)
Michael A. Lombardi, Aaron P. Dahlen
This paper describes a common-view disciplined oscillator (CVDO) that locks to a reference time scale through the use of common-view Global Positioning System (GPS) satellite measurements. A Proportional-Integral-Derivative (PID) controller obtains near

How Accurate is a Radio Controlled Clock?

March 1, 2010
Author(s)
Michael A. Lombardi
This paper discusses the factors that determine the accuracy of radio controlled clocks. The topics covered including the accuracy of the time signal station, path delay, synchronization errors, and the time error that accumulates between synchronizations.

NIST Time and Frequency Bulletin

January 5, 2010
Author(s)
Eyvon Petty
The Time and Frequency Bulletin provides information on performance of time scales and a variety of broadcasts (and related information) to users of the NIST services)

Distributing UTC(NIST) to Industrial Time and Frequency Users

November 18, 2009
Author(s)
Michael A. Lombardi, Victor S. Zhang
The National Institute of Standards and Technology (NIST) maintains one of the world s most accurate and stable time scales, UTC(NIST), as well as the NIST-F1 cesium fountain, the primary frequency standard for the United States. These standards are

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

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

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
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