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Physics

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Displaying 1126 - 1150 of 2574

Optical-Frequency Measurements with a Kerr Microcomb and Photonic-Chip Supercontinuum

February 27, 2018
Author(s)
Erin S. Lamb, David R. Carlson, Daniel D. Hickstein, Jordan R. Stone, Scott A. Diddams, Scott B. Papp
Dissipative solitons formed in Kerr microresonators offer the promise of chip-scale frequency combs that can extend precision metrology outside of a laboratory environment. We explore the creation of an octave-spanning, 15 GHz repetition rate microcomb

NIST Time and Frequency Bulletin

February 23, 2018
Author(s)
Kathryn R. Stephenson
The Time and Frequency Bulletin provides information on performance of time scales and a variety of broadcasts (and related information) to users of the NIST services.

Weak and Strong Gels and the Emergence of the Amorphous Solid State

February 23, 2018
Author(s)
Jack F. Douglas
Gels are amorphous solids whose macroscopic viscoelastic response derives from contraints in the material that serve to localize the constituent molecules or particles about their average positions in space. These contraints may either be local in nature

Blade Coating Aligned, High-Performance, Semiconducting-Polymer Transistors

February 22, 2018
Author(s)
Lee J. Richter, Hyun W. Ro, Regis J. Kline, Daniel A. Fischer, Dean M. DeLongchamp, Lars Thomsen, Christopher McNeil, Dawei Wu, Maria Kaplan, Eliot H. Gann
Recent demonstration of mobilities in excess of 10 cm2V-1s-1 have energized research in solution deposition of polymers for thin film transistor applications. Due to the lamella motif of most soluble, semiconducting polymers, the local mobility is

Topological Rigidification of Flexible Polymers in Solution

February 22, 2018
Author(s)
Jack F. Douglas, Fernando Vargas-Lara
We use molecular dynamic simulations on a coarse-grained model for flexible polymers in solution to study how molecular topology affects the intrinsic rigidity of polymeric chains. In particular, we study how polymeric "topological complexity", defined by

What Does the Tg of Thin Polymer Films Really Tell Us?

February 22, 2018
Author(s)
Wengang Zhang, Francis W. Starr, Jack F. Douglas
The disparate results for Tg shifts in ultra-thin polymer films with the same film thickness, substrate, and chemistry raises the question of whether Tg is a useful way to characterize thin films. Underlying many Tg measurements is the assumption that Tg

The 12C(n,2n)11C Cross Section from Threshold to 26.5 MeV

February 20, 2018
Author(s)
Ryan P. Fitzgerald, M Yuly, T Eckert, G Hartshaw, S. J. Padalino, D. N. Polsin, M. Russ, A. T. Simone, C R. Brune, T N. Massey, C. E. Parker, T. C. Sangster, S P. Regan
The 12C(n, 2n)11C cross section was measured from just below threshold to 26.5 MeV using the pelletron accelerator at Ohio University. Monoenergetic neutrons, produced via the 3H(d,n)4He reaction, were allowed to strike targets of polyethylene and graphite

Fractal Universality in Near-Threshold Magnetic Lanthanide Dimers

February 16, 2018
Author(s)
Eite Tiesinga, Constantinos Makrides, Ming Li, Svetlana Kotochigova
Ergodic quantum systems are often quite alike whereas non-ergodic, fractal systems are unique and display characteristic properties. In this paper we explore one of such fractal systems, weakly-bound dysprosium lanthanide molecules in an external magnetic

Carbon Nanotube-Based Black Coatings

February 15, 2018
Author(s)
John H. Lehman, Christopher S. Yung, Nathan A. Tomlin, Davis R. Conklin, Michelle S. Stephens
It has been shown that coatings comprised of carbon nanotubes are very black; that is, characterized by low reflectance over a broad wavelength range from the visible to far infrared. Arguably there is no other material that is comparable. This is

Quasi-Phase-Matched Supercontinuum Generation in Photonic Waveguides

February 1, 2018
Author(s)
Daniel D. Hickstein, Grace Kerber, David R. Carlson, Lin Chang, Daron A. Westly, Kartik A. Srinivasan, Abijith S. Kowligy, John Bowers, Scott A. Diddams, Scott B. Papp
Supercontinuum generation in on-chip waveguides is a versatile source of broadband light and the generated spectrum is determined by the phase-matching conditions. Here we show that quasi- phase-matching via periodic modulations of the waveguide structure

Implementation of SDR TWSTFT in UTC Computation

January 30, 2018
Author(s)
Zhiheng Jiang, Felicitas Arias, Victor S. Zhang, Yi-Jiun Huang, Joseph Ackhar, Dirk Piester, Shinn-Yan Lin, Wenjun Wu, Andrey Naumov, Sung-hoon Yang, Jerzy Nawrocki, Ilaria Sesia, Christian Schlunegger, Kun Liang
Two-Way Satellite Time and Frequency Transfer (TWSTFT or TW for short) is a primary technique for the realization of Coordinated Universal Time (UTC), which is computed by the International Bureau of Weights and Measures (BIPM). TWSTFT is carried out

Metrological and legal traceability of time signals

January 30, 2018
Author(s)
Demetrios Matsakis, Judah Levine, Michael A. Lombardi
Metrological traceability requires an unbroken chain of calibrations that relate to a reference, with each calibration having a documented measurement uncertainty. In the field of time and frequency metrology, the desired reference is usually Coordinated

Improving packet synchronization in an NTP server

January 29, 2018
Author(s)
Andrew N. Novick, Michael A. Lombardi, Kevin Franzen, John Clark
A computer or dedicated client can use the Network Time Protocol (NTP) to synchronize an internal clock to a server that is synchronized by a 1 pulse-per-second (pps) signal from a national timing laboratory. Measuring an NTP server on a local area network

STM patterned nanowire measurements using photolithographically defined implants in Si(100)

January 29, 2018
Author(s)
Aruna N. Ramanayaka, Hyun Soo Kim, Ke Tang, Xiqiao Wang, Richard M. Silver, Michael D. Stewart, Joshua M. Pomeroy
Using photolithographically defined implant wires for electrical connections, we demonstrate measurement of a scanning tunneling microscope (STM) patterned nanoscale electronic device on Si(100), eliminating the onerous alignment procedures and electron

Synthetic clock transitions via continuous dynamical decoupling

January 16, 2018
Author(s)
Ian B. Spielman, Nathan Lundblad, Ana Valdes-Curiel, Dimitrius Trypogeorgos
Decoherence of quantum systems due to uncontrolled fluctuations of the environment presents fundamental obstacles in quantum science. `Clock' transitions which are insensitive to such fluctuations are used to improve coherence, however, they are not
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