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Displaying 1326 - 1350 of 2503

Measurement of AM-to-PM Conversion in a Quartz-MEMS Resonator

May 9, 2016
Author(s)
Craig W. Nelson, Archita Hati, David A. Howe
This work investigates the new aspects of the non-linear response in a quartz-MEMS resonator at 635 MHz. We characterize its major cause of AM-to-PM conversion as a function of power and drive frequency; this is important in developing noise compensation

Power Splitter Thermal Noise Correlations in Cross-spectrum Noise Measurements

May 9, 2016
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
We discuss collapse of the cross-spectrum phase noise measurement of thermally-limited oscillator due to anti-correlated thermal noise of the Wilkinson power splitter. We also examine effect of thermal noise of various resistive power splitters on such

Practical Evaluation of a 50 km Fiber Link Utilizing a Commercial Modem

May 9, 2016
Author(s)
Corey A. Barnes, Archita Hati, Craig W. Nelson, David A. Howe
We evaluate the stability of two-way time and frequency transfer over a 50 km fiber optic link established using a commercially available fiber optic modem. For this evaluation we report the residual phase noise, total Allan deviation, total time deviation

Frequency shift mitigation in a cold-atom CPT clock

May 8, 2016
Author(s)
Xiaochi Liu, John Kitching, Elizabeth Donley, Eugene N. Ivanov
An upgrade in the laser interrogation system for our cold-atom clock based on coherent population trapping has resulted in a reduced light shift. The new approach makes use of an electro-optic modulator to significantly reduce the phase coherence of the

Magnetic phases of spin-1 spinorbit-coupled Bose gases

May 1, 2016
Author(s)
Ian B. Spielman, Daniel Campbell, Ryan Price, Ana Valdes-Curiel, Andika Putra, Dimitrius Trypogeorgos
Phases of matter are characterized by order parameters describing the type and degree of order in a system. Here we experimentally explore the magnetic phases present in a near-zero temperature spin-1 spin–orbit-coupled atomic Bose gas and the quantum

"Perpendicular laser cooling with a rotating wall potential in a Penning trap"

April 26, 2016
Author(s)
Joseph W. Britton, Justin G. Bohnet, John Bollinger, Steven B. Torrisi
We investigate the impact of a rotating wall potential on perpendicular laser cooling in a Penning ion trap. By including energy exchange with the rotating wall, we extend previous Doppler laser cooling theory and show that low perpendicular temperatures

A Study on Reducing the Diurnal in the Europe-to-Europe TWSTFT Links.

April 4, 2016
Author(s)
Victor S. Zhang, Thomas E. Parker, Shengkang Zhang
Most of the Two-Way Satellite Time and Frequency Transfer (TWSTFT or TW) links exhibit a daily variation (diurnal) on the order of 1 ns in the differences. The stability of TW is degraded by the diurnal. Many studies on the sources of diurnal have been

Cross-spectral Collapse from Anti-correlated Thermal Noise in Power Splitters

April 4, 2016
Author(s)
Craig Nelson, Archita Hati, David A. Howe
We discuss the cross-spectral collapse due to anti-correlated thermal noise that originates from the common-mode power divider (splitter) in a cross-spectrum noise measurement system. We studied this effect for different power splitters and discuss its

Extended Source Interferometry in the Compact Regime

April 4, 2016
Author(s)
Bruno M. Pelle, Gregory W. Hoth, Stefan Riedl, John E. Kitching, Elizabeth A. Donley
We present an atom interferometer based on an expanding cloud of laser-cooled atoms sensitive to rotations along two axes and acceleration along one axis in an effective volume of 1 cm3. We observed spatially resolved fringes by imaging the expanding cloud

The 2015 TWSTFT calibration for UTC and related time links

April 4, 2016
Author(s)
Zhiheng Jiang, Dirk Piester, Christian Schlunegger, Erik Dierks, Javier Galindo, Demetrios Matsakis, Victor S. Zhang
Two-Way Satellite Time and Frequency Transfer (TWSTFT or TW) is one of the primary time transfer techniques for UTC generation. Although it has expensive financial requirements it provides highly accurate calibration, and provides both robustness and

Measuring Time and Comparing Clocks

April 1, 2016
Author(s)
Judah Levine
I will discuss methods of comparing and synchronizing clocks and the procedure of characterizing their performance in terms of the two-sample Allan variance. I will describe methods that are used when the device under test and the reference device are in

Towards Establishing Compact Imaging Spectrometer Standards

March 31, 2016
Author(s)
David W. Allen, Elmer T. Slonecker, Ronald G. Resmini
Remote sensing science is currently undergoing a tremendous expansion in the area of hyperspectral imaging (HSI) technology. Spurred largely by the explosive growth of Unmanned Aerial Vehicles (UAV), sometimes called Unmanned Aircraft Systems (UAS), or

Probing beyond the laser coherence time in optical clock comparisons

March 30, 2016
Author(s)
David B. Hume, David R. Leibrandt
We develop protocols that circumvent the laser noise limit in optical clock comparisons by synchronous probing of two clocks using phase-locked local oscillators. This allows for probe times longer than the laser coherence time, avoids the Dick effect, and

EUV-induced oxidation of carbon on TiO2

March 25, 2016
Author(s)
Nadir S. Faradzhev, Shannon B. Hill
Previously we reported on the etch rates of C on TiO2 by oxidizers including NO, O3 and H2O2 when irradiated by extreme ultraviolet (EUV) radiation at 13.5 nm [Faradzhev et al., J.Phys. Chem. C, 117 (2013) 23072-23081]. We demonstrated that the intensity

Dispersion engineered resonator on-a-chip

March 14, 2016
Author(s)
Scott A. Diddams, Ki Youl Yang, Xu Yi, Hansuek Lee, Dong Yoon Oh, Kerry J. Vahala, Katja M. Beha, Daniel C. Cole, Pascal P. Del'Haye, Scott B. Papp
Control of dispersion in fiber optical waveguides has long been important in optical fiber communications systems, and more recently for continuum generation through self phase modulation. The wavelength at which the group velocity dispersion crosses zero

Oscillator PM-noise reduction from correlated AM-noise

March 11, 2016
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
We demonstrate a novel technique for reducing the phase modulation (PM) noise of an oscillator in steady state as well as under vibration. It utilizes correlation between PM noise and amplitude modulation (AM) noise that can originate from the oscillator's

Usage analysis of a national internet time service

March 8, 2016
Author(s)
Jeffrey A. Sherman, Judah Levine
The Internet Time Service (ITS) at the National Institute of Standards and Technology (NIST) currently receives over 12 billion time requests per day. ITS servers derive their system time from the NIST atomic-referenced timescale and distribute it freely

Cross-spectrum Measurement of Thermal-noise Limited Oscillators

March 1, 2016
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
Cross-spectrum analysis is a commonly-used technique for the detection of phase and amplitude noise of a signal in the presence of interfering noise. It extracts the desired correlated noise from two time series which also contain uncorrelated interfering

Validation and Verification of Collisional-Radiative Models

February 25, 2016
Author(s)
Yuri Ralchenko
Quality control is as relevant to scientific computing as to any other software. For complex collisional-radiative (CR) models that are used to calculate plasma population kinetic parameters and spectra, each computer code is expected to be thoroughly
Displaying 1326 - 1350 of 2503
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