1,632 research outputs found
On the electromagnetic form factors of the proton from generalized Skyrme models
We compare the prediction of Skyrme-like effective Lagrangians with data for
electromagnetic form factors of proton and consider the possibility of fixing
the parameters of these higher-order Lagrangians. Our results indicate that one
or two-parameter models can lead to better agreement with the data but more
accurate determination of the effective Lagragian faces theoretical
uncertainties.Comment: 8 pages, 2 figures, revte
Astronomical spectrograph calibration with broad-spectrum frequency combs
Broadband femtosecond-laser frequency combs are filtered to
spectrographically resolvable frequency-mode spacing, and the limitations of
using cavities for spectral filtering are considered. Data and theory are used
to show implications to spectrographic calibration of high-resolution,
astronomical spectrometers
Impact of Groundwater Flow on Permafrost Degradation and Transportation Infrastructure Stability
INE/AUTC 13.0
Measurement of excited-state transitions in cold calcium atoms by direct femtosecond frequency-comb spectroscopy
We apply direct frequency-comb spectroscopy, in combination with precision cw
spectroscopy, to measure the transition
frequency in cold calcium atoms. A 657 nm ultrastable cw laser was used to
excite atoms on the narrow ( Hz) clock transition, and the direct output of the frequency comb was
used to excite those atoms from the state to the state. The resonance of this second stage was detected by observing a
decrease in population of the ground state as a result of atoms being optically
pumped to the metastable states. The transition frequency is measured to be kHz; which is an improvement by almost four orders of magnitude over
the previously measured value. In addition, we demonstrate spectroscopy on
magnetically trapped atoms in the state.Comment: 4 pages 5 figure
Efficient 1 GHz Ti:sapphire laser with improved broadband continuum in the infrared
We demonstrate a 1 GHz prismless femtosecond Ti:sapphire ring laser which
emits 890 mW for 7.6W of pump power over a continuum extending from 585 to 1200
nm at -20 dB below the maximum. A broadband continuum is obtained without
careful mirror dispersion compensation, with the net cavity
group-delay-dispersion having -50 to +100 fs2 oscillations from 700 to 900 nm.
Further broadening is obtained by use of a slightly convex cavity mirror that
increases self-phase modulation. 17% (75%) of the intracavity (output) power is
generated in single-pass through the crystal, outside the cavity bandwidth and
concentrated in the low gain infrared region from 960 to 1200 nm. This laser
seems well suited for optical frequency metrology, possibly allowing easier
stabilization of the carrier-to-envelope offset frequency without use of
photonic fibers
Kilohertz-resolution spectroscopy of cold atoms with an optical frequency comb
We have performed sub-Doppler spectroscopy on the narrow intercombination
line of cold calcium atoms using the amplified output of a femtosecond laser
frequency comb. Injection locking of a 657-nm diode laser with a femtosecond
comb allows for two regimes of amplification, one in which many lines of the
comb are amplified, and one where a single line is predominantly amplified. The
output of the laser in both regimes was used to perform kilohertz-level
spectroscopy. This experiment demonstrates the potential for high-resolution
absolute-frequency spectroscopy over the entire spectrum of the frequency comb
output using a single high-finesse optical reference cavity.Comment: 4 pages, 4 Figure
Observation and absolute frequency measurements of the 1S0 - 3P0 optical clock transition in ytterbium
We report the direct excitation of the highly forbidden (6s^2) 1S0 - (6s6p)
3P0 optical transition in two odd isotopes of ytterbium. As the excitation
laser frequency is scanned, absorption is detected by monitoring the depletion
from an atomic cloud at ~70 uK in a magneto-optical trap. The measured
frequency in 171Yb (F=1/2) is 518,295,836,593.2 +/- 4.4 kHz. The measured
frequency in 173Yb (F=5/2) is 518,294,576,850.0 +/- 4.4 kHz. Measurements are
made with a femtosecond-laser frequency comb calibrated by the NIST cesium
fountain clock and represent nearly a million-fold reduction in uncertainty.
The natural linewidth of these J=0 to J=0 transitions is calculated to be ~10
mHz, making them well-suited to support a new generation of optical atomic
clocks based on confinement in an optical lattice.Comment: 4 pages, 3 figure
Optical Lattice Induced Light Shifts in an Yb Atomic Clock
We present an experimental study of the lattice induced light shifts on the
1S_0-3P_0 optical clock transition (v_clock~518 THz) in neutral ytterbium. The
``magic'' frequency, v_magic, for the 174Yb isotope was determined to be 394
799 475(35)MHz, which leads to a first order light shift uncertainty of 0.38 Hz
on the 518 THz clock transition. Also investigated were the hyperpolarizability
shifts due to the nearby 6s6p 3P_0 - 6s8p 3P_0, 6s8p 3P_2, and 6s5f 3F_2
two-photon resonances at 759.708 nm, 754.23 nm, and 764.95 nm respectively. By
tuning the lattice frequency over the two-photon resonances and measuring the
corresponding clock transition shifts, the hyperpolarizability shift was
estimated to be 170(33) mHz for a linear polarized, 50 uK deep, lattice at the
magic wavelength. In addition, we have confirmed that a circularly polarized
lattice eliminates the J=0 - J=0 two-photon resonance. These results indicate
that the differential polarizability and hyperpolarizability frequency shift
uncertainties in a Yb lattice clock could be held to well below 10^-17.Comment: Accepted to PR
Enhancing Key Digital Literacy Skills: Information Privacy, Information Security, and Copyright/Intellectual Property
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Observation of spinor dynamics in optically trapped 87Rb Bose-Einstein Condensates
We measure spin mixing of F=1 and F=2 spinor condensates of 87Rb atoms
confined in an optical trap. We determine the spin mixing time to be typically
less than 600 ms and observe spin population oscillations. The equilibrium spin
configuration in the F=1 manifold is measured for different magnetic fields and
found to show ferromagnetic behavior for low field gradients. An F=2 condensate
is created by microwave excitation from F=1 manifold, and this spin-2
condensate is observed to decay exponentially with time constant 250 ms.
Despite the short lifetime in the F=2 manifold, spin mixing of the condensate
is observed within 50 ms.Comment: 4 pages, 6 figure
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