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Physics

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Displaying 1626 - 1650 of 2516

Cold-atom double-lambda coherent population trapping clock

October 31, 2013
Author(s)
Elizabeth A. Donley, Francois-Xavier R. Esnault, Eric M. Blanshan, Eugene N. Ivanov, Robert E. Scholten, John E. Kitching
Miniature atomic clocks based on coherent population trapping (CPT) states in thermal atoms are emerging as an important component in many field applications, particularly where satellite frequency standards are not accessible. Cold-atom CPT clocks promise

Time Required to Injection-Lock Spin Torque Nanoscale Oscillators

October 29, 2013
Author(s)
William H. Rippard, Matthew R. Pufall, Anthony B. Kos
We have injection-locked a spin-transfer oscillator to a second-harmonic electrical input signal and measured the relative phase and amplitude of the device output as a function of DC current under steady-state conditions. The relative phase of the device

Imaging topological edge states in silicon photonics

October 20, 2013
Author(s)
Mohammad Hafezi, Jingyun Fan, Alan L. Migdall, Jacob M. Taylor
Systems with topological oder exhibit exotic phenomena including fractional statistics. While most systems with topological order have been electronic, advances in our understanding of synthetic gauge fields have enabled realization of topological order in

Relativistic CI calculations of spectroscopic data for the 2p6 and 2p53l configurationsin Ne-like ions between Mg III and Kr XXVII

October 10, 2013
Author(s)
P. Jonsson, P. Bengtsson, J. Ekman, S. Gustafsson, L. B. Karlsson, G. Gaigalas, D. Kato, Charlotte F. Fischer, I. Murakami, H. A. Sakaue, H. Hara, T. Watanabe, N. Nakamura, N. Yamamoto
Energies, E1, M1, E2, M2 transition rates, oscillator strengths, and lifetimes from relativistic configuration interaction calculations are reported for the states of the 2p6, 2p53s, 2p53p, and 2p53d, configurations in all Ne-like ions between Mg III and

Automated Control of National Time Standards via the SIM Time Scale

September 27, 2013
Author(s)
Michael A. Lombardi, J. Mauricio Lopez-Romero, Nelida Diaz-Munoz
This paper describes a frequency and time control system developed by the Sistema Interamericano de Metrologia (SIM). Due to limited resources, some SIM national metrology institutes maintain a low-cost rubidium clock as their national time standard

EUV spectra from N-shell ions of Gd, Dy and W

September 23, 2013
Author(s)
Deirdre Kilbane, John D. Gillaspy, Yuri Ralchenko, Joseph Reader, G. O'Sullivan
Measurements of extreme ultraviolet radiation from gadolinium, dysprosium and tungsten ions with an open n=4 shell were performed at the National Institute of Standards and Technology. The ions were produced and confined in an electron beam ion trap and

EUV-Driven Carbonaceous Film Deposition and Its Photo-oxidation on a TiO2 Film Surface

September 23, 2013
Author(s)
Nadir S. Faradzhev, Monica McEntee, John Yate, Shannon B. Hill, Thomas B. Lucatorto
We report the photo-deposition of a carbonaceous layer grown on a TiO2 thin film by EUV radiation-induced chemistry of adsorbed n-tetradecane and the subsequent photo-oxidation of this film. It is found by chemical analysis of the C layer that irradiation

Magnetic-dipole lines in 3dn ions of high-Z elements: identification, diagnostic potential, and dielectronic resonances

September 23, 2013
Author(s)
Yuri Ralchenko, John D. Gillaspy, Joseph Reader, Dmitry D. Osin, John J. Curry, Yuri A. Podpaly
We present a review of measurements and analyses of extreme-ultraviolet magneticdipole (M1) lines in 50-60-times ionized atoms of tungsten, hafnium, tantalum, and gold with an open 3d shell. The spectra were measured with the electron beam ion trap at the

Spiral Resonators for On-Chip Laser Frequency Stabilization

September 17, 2013
Author(s)
Scott A. Diddams, Hansuek Lee, Myoung-Gyun Suh, Tong Chen, Jiang Li, Kerry J. Vahala
Frequency references are indispensable to radio, microwave, and time keeping systems, with far reaching applications in navigation, communi- cation, remote sensing, and basic science. Over the past decade there has been an optical revo- lution in time

GPS Integrity Architecture Opportunities

September 16, 2013
Author(s)
Marc A. Weiss, Calvin Miles, Karl J. Kovach, John Dobyne, Karen Van Dyke
The Global Positioning System (GPS) integrity architecture forms the basis for several GPS integrity augmentation systems, most notably, the Wide Area Augmentation System (WAAS), Receiver-based Autonomous Integrity Monitoring (RAIM) and its proposed

Quantum simulation and many-body physics with hundreds of trapped ions

September 14, 2013
Author(s)
John J. Bollinger, Joseph W. Britton, Brian C. Sawyer
By employing forces that depend on the internal electronic state (or spin) of an atomic ion, the Coulomb potential energy of a trapped ion crystal can be modified in a spin-dependent way to mimic effective quantum spin Hamiltonians. We use simple models to

An atomic clock with 10 -18 instability

September 13, 2013
Author(s)
Andrew D. Ludlow, Nathan M. Hinkley, Jeffrey A. Sherman, Nate B. Phillips, Marco Schioppo, Nathan D. Lemke, Kyle P. Beloy, M Pizzocaro, Christopher W. Oates
Atomic clocks have been transformational in science and technology, leading to innovations such as global positioning, advanced communications, and tests of fundamental constant variation. Next-generation optical atomic clocks can extend the capability of

A Study of the Diurnal in the Transatlantic TWSTFT Difference

September 7, 2013
Author(s)
Victor S. Zhang, Thomas E. Parker
The daily variation (diurnal) in the two-way satellite time and frequency transfer (TWSTFT) difference is one of the most significant instabilities of the TWSTFT technique. The diurnal comes from the daily delay change of the TWSTFT signal paths. In recent

Reply to "Comment on: 'Ultrafast Demagnetization Measurements Using Extreme Ultraviolet Light: Comparison of Electronic and Magnetic Contributions'"

September 4, 2013
Author(s)
Justin Shaw, Thomas J. Silva, Hans Nembach, Emrah Turgut, Patrik Grychtol, Chan La-O-Vorakiat, Henry C. Kapteyn, Margaret M. Murnane, Stefan Mathias, Martin Aeschlimann, Claus Schneider, Daniel E. Adams
In the following, we show that the conclusions of our article titled "Ultrafast Demagnetization Measurements Using Extreme Ultraviolet Light: Comparison of Electronic and Magnetic Contributions" are correct. The Comment of Vodungbo et al. argues that a

State-of-the-Art RF Signal Generation From Optical Frequency Division

September 2, 2013
Author(s)
Archita Hati, Craig W. Nelson, Corey A. Barnes, Danielle G. Lirette, Tara M. Fortier, Franklyn J. Quinlan, Jason A. DeSalvo, Andrew D. Ludlow, Till P. Rosenband, Scott A. Diddams, David A. Howe
We present the design of a novel, ultra-low phase-noise frequency synthesizer implemented with extremely low noise regenerative frequency dividers. This synthesizer generates eight outputs viz. 1.6 GHz, 320 MHz, 160 MHz, 80 MHz, 40 MHz, 20 MHz, 10 MHz and

Detection of l-C3H+ in Sgr B2(N) and Sgr B2(OH) and Refinement of its Spectroscopic Constants via the Publicly Available PRIMOS Survey and the Barry E. Turner Legacy Survey

September 1, 2013
Author(s)
Francis J. Lovas, Brett A. McGuire, P. B. Carroll, Ryan A. Loomis, Geoffery A. Blake, Jan M. Hollis, Phillip R. Jewell, Anthony J. Remijan
Pety et al. (2012) recently reported the detection and assignment of l-C3H+ in the Horsehead nebula. Here, we expand that analysis to include the J = 1 - 0 and J = 2 - 1 transitions of l-C3H+ observed in absorption towards Sgr B2(N) in data from the

Giant Secondary Grain Growth in Cu Films on Sapphire

August 1, 2013
Author(s)
David L. Miller, Mark W. Keller, Justin Shaw, Katherine P. Rice, Robert Keller, Kyle M. Diederichsen
Single crystal metal films on insulating substrates are attractive for microelectronics and other applications, but they are difficult to achieve on macroscopic length scales. The conventional approach to obtaining such films is epitaxial growth at high
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