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Physics

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Displaying 1876 - 1900 of 2574

Efficiency of quasiparticle evacuation in superconducting devices

January 23, 2012
Author(s)
Sukumar Rajauria, L. Pascal, P. Gandit, F. Hekking, B. Pannetier, H. Courtois
We have studied the di®usion of excess quasiparticles in a current-biased superconductor strip in proximity to a metallic trap junction. In particular, we have measured accurately the superconductor temperature at a near-gap injection voltage. By analyzing

Fourier, Gauss, Fraunhofer, Porod and the Shape from Moments Problem

January 17, 2012
Author(s)
Gregg M. Gallatin
We show how the Fourier transform of a shape in any number of dimensions can be simplified using Gauss' law and evaluated explicitly for polygons in two dimensions, polyhedra three dimensions, etc. We also show how this combination of Fourier and Gauss can

Extension and new level optimization of the Ne IV spectrum

January 13, 2012
Author(s)
Alexander Kramida, C M. Brown, Uri Feldman, Joseph Reader
Spectra of Ne emitted by a Penning discharge were recorded in the extreme ultraviolet (EUV) region between 140 Å and 359 Å on a 10.7 m grazing-incidence spectrograph with phosphor storage image plates. These spectra provided 33 newly identified lines of Ne

Atom-number amplification in a magneto-optical trap via stimulated light forces

January 10, 2012
Author(s)
Elizabeth A. Donley, Tara C. Liebisch, Eric M. Blanshan, John E. Kitching
We have decelerated an atomic beam of 87 Rb using a stimulated-emission slowing technique that makes use of a bichromatic standing light wave of high intensity and increased the load rate into a small magneto-optical trap by up to a factor of 20. We

NIST Time and Frequency Bulletin

January 5, 2012
Author(s)
Petrina C. Potts
The Time and Frequency Bulletin provides information on performance of time scales and a varieth of broadcasts (and related information) to users of the NIST services.

Populations of excited parabolic states of hydrogen beam in fusion plasmas

January 1, 2012
Author(s)
Oleksandr Marchuk, Yuri Ralchenko
The injection of a neutral beam into the core of magnetically confined plasmas is a foundation for various plasma diagnostics, including charge-exchange recombination spectroscopy, beam-emission spectroscopy and motional Stark effect diagnostics. We review

M-ary state phase-shift keying discrimination below the homodyne limit

December 22, 2011
Author(s)
Francisco E. Becerra Chavez, Jingyun Fan, Gerald Baumgartner, Sergey V. Polyakov, Julius Goldhar, Jonathan Kosloski, Alan L. Migdall
We investigate a strategy for M-ary discrimination of nonorthogonal phase states with error rates below the homodyne limit. This strategy uses feed forward to update a reference field and Signal nulling for the state discrimination. We experimentally

Insensitivity of Sub-Kelvin Electron-Phonon Coupling to Substrate Properties

December 16, 2011
Author(s)
Jason M. Underwood, Peter J. Lowell, Galen C. O'Neil, Joel N. Ullom
We have examined the role of the substrate on electron-phonon coupling in normal metal films of Mn-doped Al at temperatures below 1 K. Normal metal-insulator-superconductor junctions were used to measure the electron temperature in thin metal films as a

Trapped-Ion State Detection through Coherent Motion

December 9, 2011
Author(s)
Till P. Rosenband, David Hume, Chin-Wen Chou, David R. Leibrandt, Michael J. Thorpe, David J. Wineland
Coherent control of trapped atomic ions has led to several recent advances in quantum information processing 1 and precision spectroscopy 2. A basic requirement for these and other quantum-metrology experiments is the ability to detect the state of an

An 84 Pixel All-Silicon Corrugated Feedhorn for CMB Measurements

December 8, 2011
Author(s)
John P. Nibarger, James A. Beall, Daniel T. Becker, Joseph W. Britton, Hsiao-Mei Cho, Anna E. Fox, Gene C. Hilton, Johannes Hubmayr, Dale Li, Kent D. Irwin, Jeffrey L. Van Lanen, Jeff McMahon, Ki Won Yoon
Silicon platelet corrugated feedhorn for cosmic microwave background (CMB) measurements in the mm wave (130 to 170 GHz) have been developed for deployment for the polarization sensitive upgrade to both the Atacama Cosmology Telescope (ACTpol) and the South

Noise floor reduction of an Er:fiber laser-based photonic microwave generator

December 1, 2011
Author(s)
Haifeng (. Jiang, Jennifer A. Taylor, Franklyn J. Quinlan, Tara M. Fortier, Scott A. Diddams
Commercially available erbium-doped mode-locked fiber lasers are compact, robust, and suitable to be the frequency divider of an ultra-low phase noise photonic microwave generator. However, for a mode-locked fiber laser with repetition rate of a few

The New SI: The Role of CODATA

December 1, 2011
Author(s)
David B. Newell, Peter J. Mohr, Barry N. Taylor
The mission of the International Council for Science : Committee on Data for Science and Technology (CODATA ) is to strengthen international science for the benefit of society by promoting improved scientific and technical data management and use. One of

Cold-collision-shift cancelation and inelastic scattering in a Yb optical lattice clock

November 28, 2011
Author(s)
Andrew D. Ludlow, Nathan D. Lemke, Jeffrey A. Sherman, Christopher W. Oates, G. Quemener, J. von Stecher, A.M. Rey
Recently, ρ-wave cold collisions were shown to dominate the density-dependent shift of the clock transition frequency in a 171Yb optical lattice clock. Here we demonstrate that by operating such a system at the proper excitation fraction, the cold

Quantum simulation of the hexagonal Kitaev model with trapped ions

November 25, 2011
Author(s)
Dietrich G. Leibfried, Roman Schmied , Janus H. Wesenberg
We present a detailed study of quantum simulations of coupled spin systems in surface-electrode ion-trap arrays, and illustrate our findings with a proposed implementation of the hexagonal Kitaev model [A. Kitaev, Annals of Physics 321,2 (2006)]. The e

High-resolution single-mode fiber-optic distributed Raman sensor for absolute temperature measurement using superconducting nanowire single-photon detectors

November 17, 2011
Author(s)
Michael G. Tanner, Shellee D. Dyer, Burm Baek, Robert Hadfield, Sae Woo Nam
We demonstrate a distributed fiber Raman sensor for absolute temperature measurement with spatial resolution on the order of 1 cm at 1550 nm wavelength in single mode fiber using superconducting nanowire single photon detectors. Rapid measurements are

Generation and characterization of high-purity, pulsed squeezed light at telecom wavelengths from pp-KTP

November 15, 2011
Author(s)
Thomas Gerrits, Martin J. Stevens, Burm Baek, Brice R. Calkins, Adriana E. Lita, Scott C. Glancy, Emanuel H. Knill, Sae Woo Nam, Richard P. Mirin, Robert Hadfield, Ryan Bennink, Warren Grice, Sander N. Dorenbos, Tony Zijlstra, Teun Klapwijk, Val Zwiller
We characterize a pp-KTP crystal designed to produce pure single mode squeezed vacuum at 1570 nm. Measurements show a raw (corrected) Hong-Ou-Mandel interference with 86 % (90 %) visibility and a circular joint spectral probability distribution with a

Characterizing Dynamic Effects of Oscillator Power Cycling

November 14, 2011
Author(s)
David A. Howe, Danielle G. Lirette, Neil Ashby, Archita Hati, Craig W. Nelson
We create a measurement technique and metrics consistent with easy interpretation to be used in development of new oscillators specifically for applications in which the oscillator’s power is turned on and off. This is useful in predicting the performance

Improvements to A Transportable Atomic Fountain Laser system

November 14, 2011
Author(s)
Paul D. Kunz, Vladislav Gerginov, Thomas P. Heavner, Steven R. Jefferts
We are developing a transportable rubidium (Rb) atomic fountain frequency standard which uses independently phase-locked diode lasers for laser-cooling. At this point in time, we have not demonstrated sub-Doppler (υKelvin) atom temperatures using out
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