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Physics

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Displaying 826 - 850 of 2466

The Interfacial Zone Around Nanoparticles in Polymer Nanocomposites

September 2, 2019
Author(s)
Jack F. Douglas, Beatriz Betancourt, Fernando Vargas-Lara, Francis W. Starr, Wengang Zhang
We perform coarse-grained simulations of model nanoparticles having a diameter on the order of 10 nm in an unentangled polymer matrix in the limit of low nanoparticle concentration to understand how the presence of nanoparticles alter the segmental

Resonant X-ray Emission and Valence-band Lifetime Broadening in LiNO3

August 28, 2019
Author(s)
John T. Vinson, Terrence J. Jach, Matthias Mueller, Rainer Unterumsberger, Burkhard Beckhoff
X-ray absorption and resonant inelastic x-ray scattering measurements are carried out on lithium nitrate LiNO3. Echoing previous studies on ammonium nitrate, the σ orbitals around the nitrogen atoms exhibit a large lifetime effect. Experimentally, this is

A semiclassical theory of phase-space dynamics of interacting bosons

August 21, 2019
Author(s)
Eite Tiesinga, Ranchu Mathew
We study the phase-space representation of dynamics of bosons in the semiclassical regime where the occupation number of the modes is large. To this end, we employ the van Vleck-Gutzwiller propagator to obtain an approximation for the Green’s function of

An atomic sensor for direct detection of weak microwave signals

August 16, 2019
Author(s)
Vladislav Gerginov, Fabio C. da Silva, Craig Nelson, Archita Hati
This paper demonstrates direct detection of weak signals at microwave frequencies based on parametric frequency conversion. The atomic medium is optically pumped by a resonant light field and prepared in a coherent atomic superposition by a weak microwave

Ramsey-Borde Matter-Wave Interferometry for Laser Frequency Stabilization at 10 -16 Frequency Instability and Below

August 13, 2019
Author(s)
Judith B. Olson, Todd Sheerin, Holly Leopardi, Roger C. Brown, Richard W. Fox, Rick Stoner, Tara M. Fortier, Christopher W. Oates, Andrew D. Ludlow
We demonstrate Ramsey-Borde (RB) atom interferometry for high performance laser stabilization with fractional frequency instability −16 for timescales between 10 and 1000s. The RB spectroscopy laser interrogates two counterpropagating 40Ca beams on the 1S

Terahertz-Rate Kerr-Microresonator Optical Clockwork

August 12, 2019
Author(s)
Tara E. Drake, Travis Briles, Daryl T. Spencer II, Jordan R. Stone, David R. Carlson, Daniel D. Hickstein, Qing Li, Daron A. Westly, Kartik A. Srinivasan, Scott A. Diddams, Scott B. Papp
Kerr microresonators generate interesting and useful fundamental states of electromagnetic radiation through nonlinear interactions of continuous-wave (CW) laser light. When implemented with photonic-integration techniques, functional devices with low

A microrod optical-frequency reference in the ambient environment

August 6, 2019
Author(s)
Wei Zhang, Frederick N. Baynes, Scott Diddams, Scott Papp
We present an ultrahigh-Q microrod resonator operated under ambient conditions that supports laser fractional frequency stabilization to the thermal-noise limit of 3 x 10−13 and a linewidth of 62 Hz. We characterize the technical-noise mechanisms for laser

Ampoules for Radioactivity Standard Reference Materials

August 6, 2019
Author(s)
Ronald Colle
Standard-sized ampoules for radioactive solution standards have been employed by the National Institute of Standards and Technology (NIST) for nearly the past 70 years. This note briefly summarizes the origins and history of the five different batches of

Three-state structural heterogeneity in a model two dimensional liquid

August 3, 2019
Author(s)
Jack F. Douglas, Tamoghna Das
Three structural populations with distinct average mobility are identi ed within an equilibrium two-dimensional Lennard-Jones uid simulated via molecular dynamics at a constant temperature and varying density. Quantifying the structure of the immediate

Anomalous spin-orbit torques in magnetic single-layer films

July 22, 2019
Author(s)
Wenrui Wang, Tao Wang, Vivek P. Amin, Yang Wang, Anil Radhakrishna, Angie Davidson, Shane Allen, Thomas J. Silva, Hendrik Ohldag, Davor Balzar, Barry L. Zink, Paul M. Haney, John Xiao, D.G. Cahill, Virginia O. Lorenz, Xin Fan
Spin-orbit interaction (SOI) couples charge and spin transport, enabling electrical control of magnetization, the foundation of next-generation spintronic devices. A quint essential example of SOI-induced transport is the anomalous Hall effect (AHE), first

Developing Next-generation Brain Sensing Technologies - A Review

July 22, 2019
Author(s)
Jacob T. Robinson, Eric Pohlmeyer, Malte C. Gather, Caleb Kemere, John Kitching, George G. Malliaras, Adam Marblestone, Kenneth L. Shepard, Thomas Stieglitz, Chong Xie
Advances in sensing technology raise the possibility of creating neural interfaces that can more effectively restore or repair neural function and reveal fundamental properties of neural information processing. To realize the potential of these

Quantum-enhanced sensing of a mechanical oscillator

July 22, 2019
Author(s)
Katherine C. McCormick, Jonas Keller, Shaun C. Burd, David J. Wineland, Andrew C. Wilson, Dietrich Leibfried
The use of special quantum states in interferometry with bosons to achieve sensitivities below the limits established by classical-like coherent dates back decades and has enjoyed immense success since its inception. Squeezed states, number states, and cat

A Cold-Atom Beam Clock, based on Coherent Population Trapping

July 17, 2019
Author(s)
John D. Elgin, Thomas P. Heavner, John E. Kitching, Elizabeth A. Donley, Jayson Denney, Evan Salim
We present results from a novel atomic clock which employs a beam of cold 87 Rb atoms and spatially separated (Ramsey) coherent population trapping interrogation of the hyperfine clock transition at 6.834 GHz. The cold atomic beam is generated through the

Experimental Upper Bound and Theoretical Expectations for Parity-Violating Neutron Spin Rotation in He-4

July 16, 2019
Author(s)
Jeffrey S. Nico, Hans P. Mumm, H E. Swanson, C. D. Bass, T. D. Bass, J M. Dawkins, J C. Horton, D Luo, William M. Snow, S. C. Walbridge, B. E. Crawford, K. F. Gan, A M. Micherdzinska, C. R. Huffer, D M. Markoff, Murad Sarsour, E I. Sharapov, V Zhumabekova, Blayne R. Heckel
Neutron spin rotation is expected from quark-quark weak interactions in the Standard Model, which induce weak interactions among nucleons that violate parity. We present the results from an experiment searching for the effect of parity violation via the

An 27 Al+ quantum-logic clock with systematic uncertainty below 10 -18

July 15, 2019
Author(s)
Samuel M. Brewer, Jwo-Sy Chen, Aaron M. Hankin, Ethan Clements, Chin-wen Chou, David J. Wineland, David Hume, David Leibrandt
We describe an optical atomic clock based on quantum-logic spectroscopy of the 1S 0 3P 0 transition in 27Al + with a systematic uncertainty of 9.0 x 10-19 and a frequency stability of 1.2 X 10 -15/(T 1/2). A 25Mg + ion is simultaneously trapped with the

Analysis of Different Computational Techniques for Calculating the Polarizability Tensors of Stem Cells with Realistic Three-Dimensional Morphologies

July 15, 2019
Author(s)
Jack F. Douglas, Beatriz Betancourt, Somen Baidya, Ahmed M. Hassan, Waleed Al-Shaikhli, Edward J. Garboczi
In living systems, it is frequently stated that form follows function by virtue of evolutionary pressures on organism development, but in the study of how functions emerge at the cellular level, function often follows form. We study this chicken versus egg

Measurements of 25 Mg + and 27 Al + magnetic constants for improved ion clock accuracy

July 15, 2019
Author(s)
Samuel M. Brewer, Jwo-Sy Chen, Aaron M. Hankin, Ethan Clements, Chin-wen Chou, Kyle Beloy, Will McGrew, Xiaogang Zhang, Robert J. Fasano, Daniele Nicolodi, Holly Leopardi, Tara Fortier, Scott Diddams, Andrew Ludlow, David J. Wineland, David Leibrandt, David Hume
We have measured the quadratic Zeeman coefficient for the 3P0 excited electronic state in 27Al+, C2=-71.944(24) MHz/T2 and the hyperfine constant of the 25Mg+ 2S1/2 ground electronic state, Ahfs = -596 254 250.981(45) Hz, with improved uncertainties. Both

Capture of Highly Charged Ions in a Pseudo-Hyperbolic Paul Trap

July 12, 2019
Author(s)
Joan M. Dreiling, Aung S. Naing, Joseph N. Tan, Joshua Hanson, Shannon Hoogerheide, Samuel M. Brewer
The confinement of ions in a radio-frequency (RF) trap (also known as a Paul trap) has proven to be advantageous in many applications. Typically, singly- or few-times-ionized atoms can be created in situ within the ion trap. Highly charged ions, on the

Single-Source Multiaxis Cold-Atom Interferometer in a Centimeter-Scale Cell

July 11, 2019
Author(s)
Yun Jhih Chen, Azure L. Hansen, Gregory W. Hoth, Eugene Ivanov, John E. Kitching, Elizabeth A. Donley
Using the technique of point source atom interferometry, we characterize the sensitivity of a multi-axis gyroscope based on free-space Raman interrogation of a single source of cold atoms in a glass vacuum cell. The instrument simultaneously measures the
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