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Displaying 1576 - 1600 of 2581

IR-enhanced Si reference detectors for 1-step scale transfers from 300 nm to 1000 nm

November 20, 2014
Author(s)
George P. Eppeldauer, Thomas Larason, Jeanne Houston, Robert Vest, Uwe Arp, Howard Yoon
IR-enhanced Si photodiodes have improved radiometric and electronic characteristics as compared to other widely used Si photodiodes and can be used as responsivity standards in the wavelength range from 300 nm to 1000 nm. Their low predicted uncertainty

Broadband Noise Limit in the Photodetection of Ultralow Jitter Optical Pulses

November 14, 2014
Author(s)
Franklyn J. Quinlan, W. Sun, Tara M. Fortier, Jean-Daniel Deschenes, Yang Fu, Scott A. Diddams, Joe Campbell
Applications with optical atomic clocks and precision timing often require the transfer of optical frequency references to the electrical domain with extremely high fidelity. Here we examine the impact of photocarrier scattering and distributed absorption

Measurement and Calculation of Absolute Single and Double Charge Exchange Cross Sections for O6+ Ions at 1.17 keV/u and 2.33 keV/u Impacting He and H2

November 10, 2014
Author(s)
J. R. Machacek, D. P. Mahapatra, D. R. Schultz, Yuri Ralchenko, A. Chutjian, J. Simcic, S. M. Madzunkov, R. J. Mawhorter
Absolute single and double charge-exchange (CE) cross sections for the astrophysically-prominent O6+ ion with the atomic and molecular targets He and H2 are reported. These collisions give rise to X-ray emissions in the interplanetary medium, planetary

A Low-Cost Time Transfer Receiver for Contributions to Coordinated Universal Time

November 6, 2014
Author(s)
Michael Lombardi, Andrew Novick, Victor S. Zhang
This paper describes a low-cost time transfer receiver that allows timing laboratories, including national metrology institutes and other designated institutions, to contribute data to the computation of Coordinated Universal Time (UTC). The time transfer

Fast transport of mixed-species ion chains within a Paul trap

November 6, 2014
Author(s)
Ryan S. Bowler, M. Palmer, John P. Gaebler, Dietrich G. Leibfried, J. G. Ceremuga
We investigate the dynamics of mixed-species ion crystals during transport between spatially distinct locations in a linear Paul trap in the diabatic regime. In a general mixed-species crystal, all degrees of freedom along the direction of transport are

Frequency Comb Generation in Superconducting Resonators

October 30, 2014
Author(s)
Robert P. Erickson, Michael Vissers, Martin O. Sandberg, Steven R. Jefferts, David P. Pappas
We have generated frequency combs spanning 0.5 to 20 GHz in superconducting λ=2 resonators at T ¼ 3 K. Thin films of niobium-titanium nitride enabled this development due to their low loss, high nonlinearity, low frequency dispersion, and high critical

Extended and Revised Analysis of Singly Ionized Tin: Sn II

October 28, 2014
Author(s)
K. Haris, Alexander Kramida, A. Tauheed
The electronic structure of singly ionized tin (Sn II) is partly a one-electron and partly a three-electron system with ground configuration 5s25p. The excited configurations are of the type 5s2nℓ in the one-electron part, and 5s5p2, 5p3 and 5s5pnℓ (nℓ =

A Cross-Benchmarking and Validation Initiative for Tokamak 3D Equilibrium Calculations

October 27, 2014
Author(s)
Geoffrey B. McFadden, Allan Reiman, Antoine Cerfon, E. Lazarus, S. Lazerson
We are pursuing a cross-benchmarking and validation initiative for tokamak 3D equilibrium calculations, with 11 codes participating: the linearized tokamak equilibrium codes IPEC and MARS-F,the time-dependent extended MHD codes M3D-C1, M3D, and NIMROD, the

Magnetoencephalography of Epilepsy with a Microfabricated Atomic Magnetrode

October 22, 2014
Author(s)
Svenja A. Knappe, Orang Alem, Alex M. Benison, Daniel S. Barth, John E. Kitching
We measured the magnetic signature of epileptiform discharges with high signal-to-noise ratio, using microfabricated atomic magnetometers based on laser spectroscopy of rubidium vapor and similar in size to scalp EEG electrodes. Sensitivity to neuronal

A geometric description of nonreciprocity in coupled two-mode systems

October 16, 2014
Author(s)
Leonardo M. Ranzani, Jose A. Aumentado
We explore the concept of nonreciprocity in coupled two-mode systems using a geometric mapping to the Poincaré sphere. From this perspective, we recast the requirements for nonreciprocity in terms of rotation and inversion symmetry arguments for the vector

Challenges of Irradiance-mode Spectral Response Measurements

October 16, 2014
Author(s)
Behrang H. Hamadani, John F. Roller, Brian P. Dougherty, Howard W. Yoon
Irradiance-mode spectral response measurements of solar cells are important because they provide a direct, reliable and accurate route for determination of the short circuit current (Isc) of solar cells under air mass 1.5 standard reference spectrum. In

High-Power and High-Linearity Photodetector Modules for Microwave Photonic Applications

October 15, 2014
Author(s)
Frederick N. Baynes, Efthymios Rouvalis, Xiaojun Xie, Qiugui Zhou, Franklyn J. Quinlan, Tara M. Fortier, Scott A. Diddams, Andreas G. Steffan, Andreas Beling, Joe C. Campbell
We demonstrate hermetically packaged InGaAs/InP photodetector modules for high performance microwave photonic applications. The devices employ an advanced photodiode epitaxial layer known as the modified uni-traveling carrier photodiode (MUTC-PD) with

Improvements in SIM Time Network and SIM Time Scale Performance

October 10, 2014
Author(s)
Michael A. Lombardi, J. Mauricio Lopez-Romero, Nelida Diaz-Munoz, E. de Carlos-Lopez, Marina Gertsvolf, Ricardo de Carvalho
We report recent results achieved within the Sistema Interamericano de Metrología (SIM) regarding the multinational cooperation program in the field of time and frequency metrology. We discuss the performance of the SIM Time Network (SIMTN) and the SIM

Phase-Sensitive Detection of Spin Pumping via the ac Inverse Spin Hall Effect

October 6, 2014
Author(s)
Thomas J. Silva, Justin M. Shaw, Hans T. Nembach, Mathias A. Weiler
Sources of pure spin currents are a fundamental building block of spintronic devices. In ferromagnet/normal metal heterostructures, spin currents are generated at ferromagnetic resonance. This is known as spin pumping, where spin currents of both dc and ac

Universal scaling law for the flow of non-Newtonian colloidal suspension

October 1, 2014
Author(s)
Nicos Martys, William L. George, Maxime Liard, Pascal Hebraud, Didier Lootens
It has been observed that flow curves (viscosity vs shear-rate) of spherical non-colloidal particles suspended in a non-Newtonian fluid matrix can be rescaled so as to collapse onto the flow curve of the matrix fluid. This result is surprising given the

High-efficiency WSi superconducting nanowire single-photon detectors operating at 2.5 K

September 24, 2014
Author(s)
Varun B. Verma, Boris Korzh, Felix Bussieres, Robert D. Horansky, Adriana E. Lita, Francesco Marsili, Hugo Zbinden, Richard P. Mirin, Sae Woo Nam
We demonstrate that superconducting nanowire single photon detectors (SNSPDs) fabricated from amorphous WSi may be operated with > 75 % system detection efficiency at a temperature approaching seventy percent of the superconducting transition temperature

Photon-number uncertainty in a superconducting transition-edge sensor beyond resolved-photon-number determination

September 10, 2014
Author(s)
Zachary H. Levine, Boris L. Glebov, Alan L. Migdall, Thomas Gerrits, Brice R. Calkins, Adriana E. Lita, Sae Woo Nam
As part of an effort to extend fundamental single-photon measurements into the macroscopic regime, we explore how best to assign photon-number uncertainties to output waveforms of a superconducting Transition Edge Sensor (TES) and how those assignments

A 40 GHz Air-Dielectric Cavity Oscillator with Low Phase Modulation

September 1, 2014
Author(s)
Archita Hati, Craig W. Nelson, Billy F. Riddle, David A. Howe
We describe the design of a low-phase modulated (PM) noise, 40 GHz oscillator that uses a conventional air-dielectric cavity resonator as a frequency discriminator to improve the PM noise of a commercial 10 GHz dielectric resonator oscillator (DRO)
Displaying 1576 - 1600 of 2581
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