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Physics

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Displaying 1501 - 1525 of 2493

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)

Optimization of Focused Ion Beam-Tomography for Superconducting Electronics

August 27, 2014
Author(s)
Aric W. Sanders, Anna E. Fox, Paul D. Dresselhaus, Alexandra Curtin
Superconducting electronics play an important role in quantum computation, ultra-low power electronics, voltage standards and magnetic sensors. Many of these applications rely on the microfabrication of superconducting circuits with multiple wiring layers

Engineering three-body interaction and Pfaffian states in circuit QED systems

August 18, 2014
Author(s)
Mohammad Hafezi, Prabin Adhikari, Jacob M. Taylor
We demonstrate a scheme to engineer the three-body interaction in circuit-QED systems by tuning a fluxonium qubit. Connecting such qubits in a square lattice and controlling the tunneling dynamics, in the form of a synthesized magnetic field, for the

Reducing oscillator PM noise from AM-PM noise correlaiton

August 14, 2014
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
We present a new scheme for improving the phase modulated (PM) noise of an oscillator from correlation between amplitude modulated (AM) and PM noise. Experimental results of this correlation effect are presented. An improvement of almost 10 dB in the PM

The Half-Life of 209Po : Revisited

August 13, 2014
Author(s)
Ronald Colle, Ryan P. Fitzgerald, Lizbeth Laureano-Perez
A substantial 25 % error in the then known and accepted (102  5) year half-life of 209Po was reported on in 2007. This error was detected from decay data from two separate primary standardizations of a 209Po solution standard, which were performed

EUV spectra of Rb-like to Ni-like dysprosium ions in an electron beam ion trap

August 12, 2014
Author(s)
Deirdre Kilbane, G. O'Sullivan, Yuri A. Podpaly, John D. Gillaspy, Joseph Reader, Yuri Ralchenko
Extreme ultraviolet radiation emitted from highly-charged dysprosium ions was measured at the National Institute of Standards and Technology. The ions were created, trapped, and excited in an electron beam ion trap (EBIT), and the spectra were recorded

Measurement of High-Energy (10 keV to 60 keV) X-Ray Spectral Line Widths with eV Accuracy

August 8, 2014
Author(s)
John F. Seely, Jack L. Glover, Lawrence T. Hudson, Yuri Ralchenko, Nino R. Pereira, U. Feldman, C. D. Stefan
A high resolution crystal spectrometer (HRCS) utilizing a crystal in transmission geometry has been developed and experimentally optimized to measure the line widths of emission lines in the 10 keV to 60 keV energy range with eV accuracy. The spectrometer

Optically-Pumped Magnetometers for MEG

August 8, 2014
Author(s)
Svenja A. Knappe, Tillman H. Sander, Lutz Trahms
Optically-pumped magnetometers (OPMs) have seen rapid progress over the last decade in terms of performance and technology development. As highly sensitive room-temperature magnetometers they present several advantages over SQUID sensors, such as the

Single-Mode Optical Fiber For High-Power, Low-Loss UV Transmission

August 8, 2014
Author(s)
Daniel H. Slichter, Yves Colombe, Andrew C. Wilson, Dietrich G. Leibfried, David J. Wineland
We report large-mode-area solid-core photonic crystal fibers made from fused silica which resist UV solarization even at relatively high optical powers. Using a process of hydrogen loading and UV irradiation of the fibers, we demonstrate stable single-mode

Speckle phase noise in coherent laser ranging: fundamental precision limitations

August 8, 2014
Author(s)
Esther Baumann, Jean-Daniel Deschenes, Fabrizio R. Giorgetta, William C. Swann, Ian R. Coddington, Nathan R. Newbury
Frequency-modulated continuous-wave laser detection and ranging (FMCW LADAR) measures the range to a surface through coherent detection of the backscattered light from a frequency-swept laser source. The ultimate limit to the range precision of FMCW LADAR

Tunable spin-spin interactions and entanglement of ions in separate controlled potential wells

August 7, 2014
Author(s)
Andrew C. Wilson, Yves Colombe, K. R. Brown, Emanuel H. Knill, Dietrich G. Leibfried, David J. Wineland
Inspired by the ideas of Richard Feynman, 1 David Deutsch, 2 Seth Lloyd 3 and others, researchers in the field of quantum information processing and simulation seek to harness the quantum-mechanical properties of well-controlled laboratory systems to

Enriching 28Si beyond 99.9998 % for semiconductor quantum computing

August 5, 2014
Author(s)
Kevin J. Dwyer, Joshua M. Pomeroy, David S. Simons, June W. Lau, Kristen L. Steffens
Using a laboratory-scale apparatus, we enrich 28Si and produce material with 40 times less residual 29Si than previously reported. Starting from natural abundance silane gas, we offer an alternative to industrial gas centrifuges for providing materials
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