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Physics

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  • Published Date
Displaying 1951 - 1975 of 2493

Revised interpretation of the Na I EUV absorption spectrum

September 27, 2010
Author(s)
Alexander Kramida
Spectral data for neutral sodium were recently compiled by Sansonetti (2008 J. Phys. Chem. Ref. Data 37 1659). In that compilation, some of the energy levels of the 2p53snl configurations were quoted from the studies of the absorption spectrum in the

Relativity and Optical Clocks

September 24, 2010
Author(s)
Chin-Wen Chou, David Hume, Till P. Rosenband, David J. Wineland
Albert Einstein's theory of relativity forced us to alter our concepts of reality. One of the more startling outcomes of the theory is that we have to give up our notions of simultaneity. This is manifest in the so-called twin paradox in which a twin

Toward Spin Squeezing with Trapped Ions

September 23, 2010
Author(s)
John J. Bollinger, Hermann Uys, Michael Biercuk, Joseph W. Britton
Building robust instruments capable of making interferometric measurements with precision beyond the standard quantum limit remains an important goal in many metrology laboratories. We describe here the basic concepts underlying spin squeezing experiments

On-Board Signal Integrity for GPS

September 21, 2010
Author(s)
Marc A. Weiss, Pradipta Shome, Ron Beard
The elements of a space-based integrity approach are to monitor the signals on-board the satellite, such that signal performance can be maintained well within desired integrity limits. These elements include 1) a system for monitoring multiple atomic

The Cooper Pair Transistor

September 17, 2010
Author(s)
Jose A. Aumentado
The Cooper pair transistor (CPT) is a superconducting electrometer that has applications in quantum information as well as fundamental superconductivity studies. Since it operates in a near-dissipationless mode, it has potential as a minimally invasive

Generation of optical coherent-state superpositions by number-resolved photon subtraction from the squeezed vacuum

September 9, 2010
Author(s)
Thomas Gerrits, Scott C. Glancy, Tracy S. Clement, Brice R. Calkins, Adriana E. Lita, Aaron Miller, Aaron J. Miller, Alan L. Migdall, Sae Woo Nam, Richard P. Mirin, Emanuel H. Knill
We have created heralded coherent-state superpositions (CSSs) by subtracting up to three photons from a pulse of squeezed vacuum light. To produce such CSSs at a sufficient rate, we used our high-efficiency photon-number-resolving transition edge sensor to

Sub-micron force detection using optically-cooled levitated microspheres

September 3, 2010
Author(s)
Andrew Geraci, Scott B. Papp, John E. Kitching
We propose an experiment using optically trapped and cooled dielectric microspheres for the detection of short-range forces. The center-of-mass motion of a microsphere trapped in vacuum can experience extremely low dissipation and quality factors of 10 12

Reflectance Factor Measurement Complications Due to Near Infrared Fluorescence

September 1, 2010
Author(s)
Maria E. Nadal, Carl C. Miller, Clarence J. Zarobila
The researchers at the National Institute of Standards and Technology (NIST) have found that the widely used orange and red color tiles unexpectedly exhibit near infrared fluorescence. An analysis of the effect this fluorescence component has on the

The Development of a Unified Time and Frequency Program in the SIM Region

September 1, 2010
Author(s)
Michael A. Lombardi, J. Mauricio Lopez-Romero
The Sistema Interamericano de Metrologia (SIM) is one of five major regional metrology organizations (RMOs) recognized by the Bureau International des Poids et Mesures (BIPM). SIM is composed of the national metrology institutes (NMIs) located in the 34

Temperature dependence of the diffusive conductivity of bilayer graphene

August 24, 2010
Author(s)
Shaffique Adam, Mark D. Stiles
Assuming diffusive carrier transport and employing an effective medium theory, we calculate the temperature dependence of bilayer graphene conductivity due to Fermi-surface broadening as a function of carrier density. We find that the temperature

yocto-Newton force detection sensitivity using trapped ions

August 22, 2010
Author(s)
Michael J. Biercuk, Joseph W. Britton, Hermann Uys, Aaron Vandevender, John Bollinger
Recent experimental advances have shown that it is possible to detect forces arising from electric fields at a level of aN/ √Hz (atto = 10 -18 through coupling of micro or nanofabricated mechanical resonators to a variety of physical systems including

Advances in Coherent Population Trapping for Atomic Clocks

August 10, 2010
Author(s)
John E. Kitching, Vishal Shah
We review advances in the field of coherent population trapping (CPT) over the last decade with respect to the application of this physical phenomenon to atomic frequency references. We provide an overview of both the basic phenomenon of coherent

A Green Laser Pointer Hazard

August 2, 2010
Author(s)
Jemellie Galang, Alessandro Restelli, Edward W. Hagley, Charles W. Clark
An inexpensive green laser pointer was found to emit 20 mW of infrared radiation during normal use. This is potentially a serious hazard that would not be noticed by most users of such pointers. We find that the problem derives from an unsafe design, and

Quantum electrical standards

August 2, 2010
Author(s)
Neil M. Zimmerman
The ampere and other electrical units defined by international agreement are presently established through challenging experiments. A redefinition of those units based on quantum laws would enable a simpler and more reliable realization.

Tripartite interactions between two phase qubits and a resonant cavity

August 1, 2010
Author(s)
Fabio Altomare, Jae Park, Katarina Cicak, Mika Sillanpaa, Michael S. Allman, Adam J. Sirois, Joshua Strong, Jed D. Whittaker, Raymond Simmonds
The ability to create and manipulate the entanglement of a large number of quantum systems lies at the heart of emerging quantum information technologies. Thus far, multipartite entanglement has been achieved using various forms of quantum bits (qubits)

A NIST Disciplined Oscillator

July 26, 2010
Author(s)
Michael A. Lombardi
The National Institute of Standards and Technology (NIST) now offers a service that provides customers with an oscillator locked to UTC(NIST), the United States national standard for frequency and time. A NIST disciplined oscillator (NISTDO) works by

Challenges in SIM to Create a Coordination Program for Time and Frequency

July 26, 2010
Author(s)
J. Mauricio Lopez-Romero, Michael A. Lombardi
The Sistema Interamericano de Metrologia (SIM), one of the world s five major regional metrology organizations (RMOs) recognized by the Bureau International des Poids et Mesures (BIPM), is comprised of national metrology institutes (NMIs) located in all 34

Generation of optical Schrodinger cat states by number-resolved squeezed photon subtraction

July 23, 2010
Author(s)
Thomas Gerrits, Scott C. Glancy, Tracy S. Clement, Brice R. Calkins, Adriana E. Lita, Aaron J. Miller, Alan L. Migdall, Aaron J. Miller, Sae Woo Nam, Richard P. Mirin, Emanuel H. Knill
We have generated and measured an approximation of an optical Schrödinger cat state by photon subtraction from squeezed vacuum. Figure 1 shows the experimental scheme. Photons are probabilistically subtracted from squeezed vacuum and detected with a photon

Ground-based observatory operations optimized and enhanced by direct atmospheric measurements

July 22, 2010
Author(s)
John T. McGraw, Peter C. Zimmer, Azzam Mansour, Dean C. Hines, Anthony B. Hull, Lisa Rossmann, Daniel C. Zirzow, Steven W. Brown, Gerald T. Fraser, Keith R. Lykke, Allan W. Smith, John T. Woodward IV, Christopher W. Stubbs
Earth's atmosphere represents a turbulent, turbid refractive element for every ground-based telescope. We describe the significantly enhanced and optimized operation of observatories supported by the combination of a lidar and spectrophotometer that allows

Hyper-Ramsey spectroscopy of optical clock transitions

July 22, 2010
Author(s)
Christopher W. Oates, V. I. Yudin, A. V. Taichenachev, Zeb Barber, Nathan D. Lemke, Andrew D. Ludlow, U Sterr, Ch. Lisdat, F Riehle
We present nonstandard optical Ramsey schemes that use pulses individually tailored in duration, phase and frequency to cancel spurious frequency shifts related to the excitation itself. In particular, the field shifts and their uncertainties can be
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