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Physics

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Displaying 1876 - 1900 of 2493

State Resolved THz Spectroscopy and Dynamics of Crystalline Peptide/Water Systems

July 11, 2011
Author(s)
Zeeshan Ahmed, Shin G. Chou, Karen M. Siegrist, David F. Plusquellic
State resolved THz studies of crystalline peptides and their hydrates have provided precise measures of the infrared active phonon modes that reflect motions on the longest possible length scales in these systems. The impact of co-crystallized water on the

Absolute transition frequencies and quantum interference in a frequency comb based measurement of the 6,7Li D lines

July 6, 2011
Author(s)
Craig J. Sansonetti, Clayton Simien, John D. Gillaspy, Joseph N. Tan, Samuel M. Brewer, Roger C. Brown, Saijun Wu, James V. Porto
Optical frequencies of the D lines of 6,7Li were measured with a relative accuracy of 5x10-11 using an optical comb synthesizer. Quantum interference in the laser induced fluorescence for the partially-resolved D2 lines was found to produce polarization

Generation of Ultrastable microwaves via optical frequency division

June 26, 2011
Author(s)
Tara Fortier, Matthew S. Kirchner, Jennifer A. Taylor, James C. Bergquist, Yanyi Jiang, Andrew Ludlow, Christopher W. Oates, Till P. Rosenband, Scott Diddams, Franklyn Quinlan, Nathan D. Lemke
A frequency-stabilized femtosecond laser optical frequency comb serves as a source of microwave signals having very low close-to-carrier phase noise. Comparison of two independent systems shows combined absolute phase noise of -100 dBc/Hz at an offset of 1

Experiment at NIST towards one-electron ions in circular Rydberg states

June 20, 2011
Author(s)
Joseph N. Tan, Samuel M. Brewer, Nicholas D. Guise
An experimental effort is underway at NIST to enable tests of theory with oneelectron ions synthesized in circular Rydberg states from captured bare nuclei. Problematic effects which limit the accuracy of predicted energy levels for low-lying states are

Imaging of nanoscale charge transport in bulk heterojunction solar cells

June 17, 2011
Author(s)
Behrang H. Hamadani, Nadine E. Gergel-Hackett, Paul M. Haney, Nikolai B. Zhitenev
We have studied the local charge transport properties of organic bulk heterojunction solar cells based on the blends of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) with a photoconductive atomic force microscope (PCAFM). We

Indistinguishability of single photons from dissimilar single-photon sources

June 14, 2011
Author(s)
Sergey V. Polyakov, Glenn S. Solomon, Edward B. Flagg, Alan L. Migdall, Andreas Muller
In quantum mechanics, particles in identical states are indistinguishable, giving rise to effects with no classical analog. For instance, the bosonic nature of light insures that upon interference two indistinguishable photons will coalesce into a single

Physicochemical characterization and in vitro hemolysis evaluation of silver nanoparticles

June 7, 2011
Author(s)
Vytautas Reipa, Jonghoon Choi, Nam S. Wang, Victoria M. Hitchins, Peter L. Goering, Robert Malinauskas
In anticipation of the increased use of various forms of silver as an antimicrobial agent in medical devices, the objective of this study was to evaluate the in vitro hemolytic potential of silver nanoparticles in dilute human blood, and to relate particle

Numerical test of few-qubit clock protocols

June 3, 2011
Author(s)
Till P. Rosenband
The stability of several clock protocols based on 2 to 20 entangled atoms is evaluated numerically, by a simulation that includes the effect of decoherence due to classical oscillator noise. In this context the squeezed states proposed by Andre, Sorensen

Recent developments in the NIST Atomic Databases

May 11, 2011
Author(s)
Alexander Kramida
New versions of the NIST Atomic Spectra Database (ASD, v. 4.0) and three bibliographic databases (Atomic Energy Levels and Spectra, v. 2.0, Atomic Transition Probabilities, v. 9.0, and Atomic Line Broadening and Shapes, v. 3.0) have recently been released

Field-test of a robust, portable, frequency-stable laser

May 10, 2011
Author(s)
David R. Leibrandt, Michael J. Thorpe, James C. Bergquist, Till P. Rosenband
We operate a frequency-stable laser in a non-laboratory environment where the test platform is a passenger vehicle. We measure the acceleration experienced by the laser and actively correct for it to achieve a system acceleration sensitivity of df/f = 11(2

Phase-coherent detection of an optical dipole force by Doppler velocimetry

May 10, 2011
Author(s)
Michael J. Biercuk, Hermann Uys, Joseph W. Britton, Aaron Vandevender, John J. Bollinger
We report phase-coherent Doppler detection of optical dipole forces using large ion crystals in a Penning trap. The technique is based on laser Doppler velocimetry using a cycling transition in 9Be+ near 313 nm and the center-of-mass (COM) ion motional

Re-optimized energy levels and Ritz wavelengths of 198Hg I

May 10, 2011
Author(s)
Alexander Kramida
Energy levels and observed spectral lines of 198Hg I were recently compiled at the National Institute of Standards and Technology (NIST) [E. B. Saloman, J. Phys. Chem. Ref. Data 35, 1519 (2006)]. In that compilation, the energy level values were optimized

Filtering noise with a quantum probe

May 5, 2011
Author(s)
John J. Bollinger
I discuss in general terms the ideas behind the manuscript "Single-ion quantum lock-in amplifier" by Kotler and colleagues which is scheduled to be published in the journal Nature. The Kotler manuscript describes a generalization of the concept of lock-in

Low Vibration Sensitivity Fiber Spools for Laser Stabilization

May 2, 2011
Author(s)
Archita Hati, T Li, B. Argence, A. Haboucha, H. Jiang, J. L. Dornaus, D Kone, A. Clairon, P. Lemonde, G. Santarelli, Craig W. Nelson, E. Burt
Mechanical vibration induced frequency noise is dominated at low Fourier frequencies in a fiber spool stabilized laser. Environmental vibration causes mechanical deformations in the fiber which induce phase fluctuations and then convert into excess

Parahydrogen-enhanced zero-field nuclear magnetic resonance

May 1, 2011
Author(s)
Svenja A. Knappe, T. Theis, P. Ganssle, G Kervem, M Ledbetter, D Budker, A Pines, John E. Kitching
Nuclear magnetic resonance (NMR) is a powerful analytical tool for determination of molecular structure and function, with broad impact in biology, medicine, materials science, and fundamental research. Conventionally, NMR is performed in multiTesla

The Impact of Dispersion on Amplitude and Frequency Noise in a Yb-fiber Laser Comb

May 1, 2011
Author(s)
Lora L. Nugent-Glandorf, Todd Johnson, Yohei Kobayashi, Scott A. Diddams
We describe a Yb-fiber based laser comb, with a focus on the relationship between net cavity dispersion and the amplitude noise and frequency noise on the comb. While tuning the net cavity dispersion from anomalous to normal, we measure the amplitude noise

Microresonator based optical frequency combs

April 29, 2011
Author(s)
Scott A. Diddams, T. J. Klippenberg
Optical frequency combs based on mode-locked laser sources have provided unprecedented measurement capabilities for optical frequencies, enabling new applications in a wide range of topics that include atomic clocks, ultracold gases, molecular

Quamtum coherence between two atoms beyond Q=10 15

April 22, 2011
Author(s)
Chin-Wen Chou, David Hume, Michael J. Thorpe, David J. Wineland, Till P. Rosenband
We place two atoms in quantum superposition states and observe coherent phase evolution for 3.4 × 10 15 cycles. Correlation signals from the two atoms yield information about their relative phase even after the probe radiation has decohered. This technique

Small-sized dichroic atomic vapor laser lock

April 21, 2011
Author(s)
Svenja A. Knappe, Changmin Lee, Geoffrey Z. Iwata, Eric Corsini, James M. Higbie, Micah P. Ledbetter, Dimitry Budkerl
Two, lightweight diode laser frequency stabilization systems designed for experiments in the field are described. Similar to a previous design, magnetic-field lines are contained within a magnetic shield enclosing permanent magnets and Rb cells, so that this

Microfabricated Chip Traps for Ions

April 12, 2011
Author(s)
Jason Amini, Joseph W. Britton, Dietrich G. Leibfried, David J. Wineland
This publication is a review of microfabricated ion traps for a book. We cover the basics of Paul traps, various geometries for realizing the traps, a number of design considerations, and, finally, a review of existing microfabricated traps.

Introduction of a DC Bias into a High-Q Superconducting Microwave Cavity

March 31, 2011
Author(s)
Rimberg J. Alex, Fei Chen, Adam J. Sirois, Raymond Simmonds
We report a technique for applying a dc voltage or current bias to the center conductor of a high-quality factor superconducting microwave cavity without significantly disturbing selected cavity modes. This is accomplished by incorporating dc bias lines

Time Through the Air

March 23, 2011
Author(s)
John P. Lowe
A brief history of the NIST WWVB low frequency (LF) radio station. This includes recent attempts at creating a sister station on the eastern side of the United States and future plans for upgrade of the existing station.
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