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Search Publications

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Displaying 851 - 875 of 2503

The Interfacial Zone in Thin Polymer Films and Around Nanoparticles in Polymer Nanocomposites

September 26, 2019
Author(s)
Jack F. Douglas, Wengang Zhang, Hamed Emamy, Fernando Vargas-Lara, Beatriz Betancourt, Francis W. Starr
We perform coarse-grained simulations of model unentangled polymer materials to quantify the range over which interfaces alter the structure and dynamics in the vicinity of the interface. We study both model polymer-nanoparticle (NP) composites with

A Century of WWV: 100th Anniversary Commemoration

September 24, 2019
Author(s)
Glenn K. Nelson
WWV was established as a radio station on October 1, 1919 with the issuance of the call letters by the U.S. Department of Commerce. This paper will observe the upcoming 100th anniversary of that event by exploring the events leading to the founding of WWV

Exceeding the Sauter-Schwinger limit of pair production with a quantum gas

September 21, 2019
Author(s)
Alina M. Pineiro Escalera, Mingwu Lu, Dina Genkina, Ian Spielman
We quantum-simulated particle-antiparticle pair production with a bosonic quantum gas in an optical lattice by emulating the requisite 1d Dirac equation and uniform electric field. We emulated field strengths far in excess of Sauter-Schwinger's limit for

Pumping and decay rates of cold atoms dark states

September 9, 2019
Author(s)
Moshe Shuker, Juniper Pollock, V. I. Yudin, John Kitching, Elizabeth Donley
Coherent dark states in atoms, created by simultaneous interaction of two coherent light fields with an atom, are of prime importance in quantum state manipulation. They are used extensively in quantum sensing and quantum information applications to build

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
Displaying 851 - 875 of 2503
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