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Physics

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Displaying 976 - 1000 of 2466

Commissioning the SALT High Resolution Spectrograph's Iodine Cell

July 6, 2018
Author(s)
Lisa A. Crause, R P. Butler, Gillian Nave, Rudi Kuhn, Blaine Lomberg, Alexei Kniazev, Steven M. Crawford, Eric Depagne
We report on commissioning the iodine absorption cell in the High Resolution Spectrograph (HRS) on the Southern African Large Telescope (SALT). The low-, medium- and high-resolution (LR, MR and HR) modes of this fibre-fed, dual-channel, white-pupil vacuum

Perpetual emulation threshold of PT-symmetric Hamiltonians

June 29, 2018
Author(s)
Ian B. Spielman, Clive Emary, Dimitris Trypogeorgos, Ana Vald?s-Curiel
We describe a technique to emulate a two-level PT-symmetric spin Hamiltonian, replete with gain and loss, using only the unitary dynamics of a larger quantum system. This we achieve by embedding the two-level system in question in a subspace of a four

J. Chem. Phys. 148, 244302 (2018); https://doi.org/10.1063/1.5029929148, 244302(C) 2018 Author(s).Fourier-transform-spectroscopicphotoabsorption cross sections andoscillator strengths for theS2 B 3..u..X 3..g system

June 25, 2018
Author(s)
G. Stark, H. Herde, J. R. Lyons, A. N. Heays, N. Oliveira, Gillian Nave, B. R. Lewis, S. T. Gibson
Photoabsorption cross sections and oscillator strengths for the strong, predissociating vibrational bands, v  11, in the S2 B 3..u .. X 3..g (v; 0) system are reported. Absorption measurements were undertaken of S2 vapor in a radio-frequency discharge

Accurate optical stabilization of a Kerr-microresonator frequency comb

June 14, 2018
Author(s)
Travis Briles, Jordan R. Stone, Tara E. Drake, Daryl T. Spencer, Connor D. Fredrick, Qing Li, Daron A. Westly, Bojan R. Ilic, Kartik A. Srinivasan, Scott A. Diddams, Scott B. Papp
Carrier-envelope-phase stabilization of optical waveforms enables exquisitely precise measurements by way of direct optical-frequency synthesis, coherent optical-to-microwave phase conversion, and control of ultrafast waveforms. We report such phase

Quantum Probability Estimation for Randomness with Quantum Side Information

June 12, 2018
Author(s)
Emanuel H. Knill, yanbao zhang, Honghao Fu
We develop a quantum version of the probability estimation framework [arXiv:1709.06159] for randomness generation with quantum side information. We show that most of the properties of probability estimation hold for quantum probability estimation (QPE)

Precision determination of absolute neutron flux

June 8, 2018
Author(s)
Jeffrey S. Nico, Maynard S. Dewey, David M. Gilliam, Andrew T. Yue, Eamon Anderson, Geoff Greene, Alexander Laptev, William M. Snow
A technique for establishing the total neutron rate of a highly-collimated monochromatic cold neutron beam was demonstrated using the method of an alpha- gamma counter. The method requires only the counting of measured rates and is independent of neutron

Octave-spanning dual frequency comb spectroscopy in the molecular fingerprint region

June 4, 2018
Author(s)
Henry R. Timmers, Abijith S. Kowligy, Alexander J. Lind, Flavio Caldas da Cruz, Nima Nader, Myles C. Silfies, Thomas K. Allison, Gabriel G. Ycas, Peter G. Schunemann, Scott B. Papp, Scott A. Diddams
Spectroscopy in the molecular fingerprint spectral region (6.5-20 $\mu$m) yields critical information on material structure for physical, chemical and biological sciences. Despite decades of effort, this portion of the electromagnetic spectrum remains

Bang-bang shortcut to adiabaticity in the Dicke model as realized in a Penning trap experiment

May 29, 2018
Author(s)
J. Cohn, Arghavan Safari-Naini, R. J. Lewis-Swan, Justin G. Bohnet, M. Garttner, Kevin Gilmore, Elena Jordan, Ana Maria Rey, John Bollinger, James K. Freericks
We introduce a bang-bang shortcut to adiabaticity for the Dicke model, which we implement via a two-dimensional array of trapped ions in a Penning trap with a spin-dependent force detuned close to the center-of-mass drumhead mode. Our focus is on employing

Generalized auto-balanced Ramsey spectroscopy of clock transitions

May 23, 2018
Author(s)
V. I. Yudin, A. V. Taichenachev, M. Y. Basalaev, T. Zanon-Willette, Juniper Wren Y. Pollock, Moshe Shuker, Elizabeth Donley, John Kitching
We develop the theory for generalised auto-balanced Ramsey spectroscopy (GABRS), which allows probe-field-induced shifts in atomic clocks to be eliminated. This universal two-loop method, apart from the clock frequency omega, requires the use of an

Revision of the ionization energy of neutral carbon

May 22, 2018
Author(s)
W L. Glab, Haris Kunari, Alexander Kramida
This publication describes a re-analysis of previously published data on neutral carbon (C I) utilizing critically examined and improved values for the line energies of the absorption spectrum of molecular iodine to calibrate the transition energies of C I

Structure and Dynamics of a Graphene Melt

May 22, 2018
Author(s)
Jack F. Douglas, Sinan Keten, Fernando Vargas-Lara, Wenjie Xia
We show by molecular dynamics simulation that bulk materials composed of graphene nanosheets exhibit fluid-like properties similar to linear polymer melts at elevated temperatures and that these materials transform into a glassy or “foam” state at low

A portable cold 87Rb atomic clock with frequency instability at one day in the 10 -15 range

May 21, 2018
Author(s)
Joshua J. Savory, F G. Ascarrunz, L I. Ascarrunz, Alessandro L. Banducci, M C. Delgado Aramburo, Y Dudin, Steven R. Jefferts
We present a small portable cold 87Rubidium atomic clock with frequency uncertainty of less than 𝟑 × 𝟏𝟎 −𝟏𝟓 in one day of averaging time. The clock is under development at SpectraDynamics for the Defense Advanced Research Projects Agency (DARPA) Portable

Effect of Local Oscillator Performance on UWB Based Indoor Localization System

May 21, 2018
Author(s)
Archita Hati, Fabio C. Da Silva, Vladislav P. Gerginov, Craig W. Nelson
We discuss the performance of a commercial Ultra-wideband (UWB) ranging technique for indoor localization. We study the influence of local oscillator's phase noise and its frequency drifts due to temperature variations on the range estimation and ranging

An Integrated-Photonics Optical-Frequency Synthesizer

May 3, 2018
Author(s)
Daryl T. Spencer, Tara E. Drake, Travis Briles, Jordan R. Stone, Laura C. Sinclair, Connor D. Fredrick, Qing Li, Daron A. Westly, Bojan R. Ilic, Aaron Bluestone, Nicolas Volet, Tin Komljenovic, Seung Hoon Lee, Dong Yoon Oh, Myoung-Gyun Suh, Ki Youl Yang, Martin H. Pfeiffer, Tobias J. Kippenberg, Erik Norberg, Kerry Vahala, Kartik A. Srinivasan, Nathan R. Newbury, Luke Theogarajan, John E. Bowers, Scott A. Diddams, Scott B. Papp
Integrated-photonics microchips now enable a range of advanced functionalities for high- coherence applications like data transmission, for highly optimized physical sensors, and for harnessing quantum states, but with size, extensibility, and portability

A Faraday-shielded, DC Stark-free optical lattice clock

May 2, 2018
Author(s)
Kyle P. Beloy, Xiaogang Zhang, William F. McGrew, Nathan M. Hinkley, Tai H. Yoon, Daniele Nicolodi, Robert J. Fasano, Stefan A. Schaeffer, Roger C. Brown, Andrew D. Ludlow
We demonstrate the absence of a DC Stark shift in an ytterbium optical lattice clock. Stray electric fields are suppressed through the introduction of an in-vacuum Faraday shield. Still, the effectiveness of the shielding must be experimentally assessed
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