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Physics

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Displaying 2151 - 2175 of 2574

Extension of the NIST tristimulus colorimeter for solid-state light source measurements

May 29, 2009
Author(s)
George P. Eppeldauer, Carl C. Miller, Thomas C. Larason, Yoshihiro Ohno
In order to obtain improved color measurement uncertainties for solid state light (SSL) sources, the second generation tristimulus colorimeter of NIST has been extended with a fifth channel to perform efficient matrix corrections for the spectral mismatch

A deep-UV optical frequency comb at 205 nm

May 25, 2009
Author(s)
Scott A. Diddams, E Peters, P Fendel, S Reinhardt, T W. Hansch, T Udem
By frequency quadrupling a picosecond pulse train from a Ti:sapphire laser at 820 nm we generate a frequency comb at 205 nm with nearly bandwidth-limited pulses. The nonlinear frequency conversion is accomplished by two successive frequency doubling stages

Observing the Quantization of Zero Mass Carriers in Graphene

May 15, 2009
Author(s)
Joseph A. Stroscio, Gregory M. Rutter, D. L. Miller, K. Kubista, W. A. de Heer, Phillip N. First
Application of a magnetic field to conductors causes the charge carriers to circulate in cyclotron orbits with quantized energies called Landau levels (LLs). These are equally spaced in normal metals and two-dimensional electron gases. In graphene, however

Time domain measurement of phase noise in a spin torque oscillator

May 13, 2009
Author(s)
Mark W. Keller, Anthony B. Kos, Thomas J. Silva, William H. Rippard, Matthew R. Pufall
We measure phase noise from the zero crossings of the voltage vs. time waveform of a spin torque nanocontact oscillating in a vortex mode. The power spectrum of the phase noise varies with Fourier frequency f as 1/f 2, consistent with frequency

Optimized Dynamical Decoupling in a Model Quantum Memory

April 23, 2009
Author(s)
Michael J. Biercuk, Hermann Uys, Aaron Vandevender, N. Shiga, Wayne M. Itano, David J. Wineland, John J. Bollinger
We demonstrate the efficacy of optimized dynamical decoupling pulse sequences in suppressing phase errors in a model quantum memory. Our experimental system consists of a crystalline array of trapped 9Be + ions in which we drive a qubit transition at $\sim

A microfabricated photonic magnetometer

April 20, 2009
Author(s)
Jan Preusser, Svenja A. Knappe, John Kitching, Vladislav Gerginov
We present initial measurements of an atomic magnetometer in which the microfabricated sensor head is coupled to the control system by optical fibers. Since there are no electrical connections, the sensor head is largely non-magnetic and degradation of the

High Fidelity Transport of Trapped-Ion Qubits through an X-Junction Trap Array

April 17, 2009
Author(s)
Brad R. Blakestad, Aaron Vandevender, Christian Ospelkaus, Jason Amini, Joseph W. Britton, Dietrich G. Leibfried, David J. Wineland
Trapped ions are a useful system for studying the elements of quantum information processing. Simple alogrithms have been demonstrated, but scaling to much larter tasks requires the ability to manipulate many qubits. To achieve this, ions could be

Probing interactions between ultracold fermions

April 17, 2009
Author(s)
G K. Campbell, M M. Boyd, J W. Thomsen, M J. Martin, S Blatt, M D. Swallows, Travis L. Nicholson, Tara Fortier, Christopher W. Oates, Scott Diddams, Nathan D. Lemke, Pascal Naidon, Paul S. Julienne, Jun Ye, Andrew Ludlow
At ultracold temperatures, the Pauli exclusion principle suppresses collisions between identical fermions. This has motivated the development of atomic clocks using fermionic isotopes. However, by probing an optical clock transition with thousands of

Electromagnetically induced transparency in a superconducting three-level system

April 16, 2009
Author(s)
Mika Sillanpaa, Katarina Cicak, Fabio Altomare, Jae Park, Raymond Simmonds, Jian Li, G. S. Paraoanu, Pertti Hakonen
When a three-level quantum system is irradiated by an intense coupling field resonant with two of the three possible transitions, the resonant absorption of the system from its ground state by an additional radiation field is suppressed. This effect, where

A simplified optical lattice clock

April 2, 2009
Author(s)
N Poli, M.G. Tarallo, M. Schioppo, A. Alberti, Giorgio Ferrari, V. Ivanov, Christopher W. Oates, G.M. Tino
While existing optical lattice clocks demonstrate a high level of performance, they remain complex experimental devices. In order to address a wider range of applications including those requiring transportable devices, it will be necessary to simplify the

First Order Sideband Pulling in Atomic Frequency Standards

April 1, 2009
Author(s)
Jon H. Shirley, Thomas P. Heavner, Steven R. Jefferts
Many high performance atomic frequency standards, including cesium fountains and most optical standards, operate with pulsed measurements, that is, an atomic sample is prepared for measurement, the measurement is made, and the process is repeated at fixed

Generation of 20 GHz, sub-40 fs pulses at 960 nm via repetition rate multiplication

April 1, 2009
Author(s)
Matthew S. Kirchner, Danielle Braje, Tara M. Fortier, A.M. Weiner, Leo Hollberg, Scott A. Diddams
Optical filtering of a stabilized 1 GHz optical frequency comb produces a 20 GHz comb with ~40 nm bandwidth (FWHM) at 960 nm. Using a low finesse Fabry-Perot cavity in a double pass configuration provides a broad cavity coupling bandwidth (delta lambda

The SIM Time Network and its Contributions to Metrology in the Americas

April 1, 2009
Author(s)
Michael A. Lombardi
The SIM Time Network (SIMTN) has been one of the great success stories of the Sistema Interamericano de Metrologia (SIM), a regional metrology organization (RMO) that includes the 34 member nations of the Organization of American States (OAS). The SIMTN

A Bose-Einstein Condensate in a Uniform Light-Induced Vector Potential

March 30, 2009
Author(s)
Yu-Ju Lin, Robert L. Compton, Abigail R. Perry, William D. Phillips, James V. Porto, Ian B. Spielman
We use a two-photon dressing field to create an effective vector gauge potential for Bose-condensed ^87Rb atoms in the F=1 hyperfine ground state. The dressed states in this Raman field are spin and momentum superpositions, and we adiabatically load the

Optical detection of NMR J -spectra at zero magnetic field

March 28, 2009
Author(s)
M Ledbetter, C.W. Crawford, A Pines, D.E. Wemmer, Svenja A. Knappe, John Kitching, D Budker
Nuclear magnetic resonance (NMR) has emerged as one of the most powerful analytical tools for elucidating molecular structure. One of the parameters typically extracted from NMR spectra which is necessary to fully understand the structure of a molecule is

High-contrast dark resonances with linearly polarized light on the D 1 line of alkali atoms with large nuclear spin

February 20, 2009
Author(s)
Ken-ichi Watabe, Takeshi Ikegami, Akifumi Takamizawa, Shinya Yanagimachi, Shin-ichi Ohshima, Svenja A. Knappe
High-contrast coherent population trapping signal was observed on the Cs-D1 line using a bichromatic linear polarized light (lin||lin) field. The maximum absorption contrast of about 10% was obtained was nearly two times higher than that measured with the

Improved signal-to-noise ratio of 10 GHz microwave signals generated with a mode-filtered femtosecond laser frequency comb

February 18, 2009
Author(s)
Scott A. Diddams, Matthew S. Kirchner, Tara M. Fortier, Danielle Braje, A. M. Weiner, Leo W. Hollberg
We use a Fabry-Perot cavity to optically filter the output of a Ti:sapphire frequency comb to integer multiples of the original 1 GHz mode spacing. This effectively increases the pulse repetition rate which is useful for several applications. In the case

Prolonging qubit coherence: dynamic decoupling schemes studied in a Penning ion trap

February 2, 2009
Author(s)
Hermann Uys, Michael J. Biercuk, Aaron Vandevender, N. Shiga, Wayne M. Itano, John J. Bollinger
We present a study of dynamical decoupling schemes for the suppression of phase erros due to various noise environments using ions in a Penning ion trap as a model ensemble of qubits. By injecting frequency noise we demonstrate that in an Ohmic noise

HBAR-Based 3.6GHz Oscillator with Low Power Consumption and Low Phase Noise

February 1, 2009
Author(s)
Hongyu Yu, Chuang-yuan Lee, Wei Pang, Hao Zhang, Alan Brannon, John E. Kitching, Eun Sok Kim
We have designed and built two oscillators, based on High-overtone Bulk Acoustic Resonators (HBAR) for application in Chip-Scale Atomic Clocks (CSAC). The measured phase noise of the 3.6-GHz oscillator is -67 dBc/Hz at 300 Hz offset and ?102 dBc/Hz at 10
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