1,529 research outputs found
Floquet Analysis of Atom Optics Tunneling Experiments
Dynamical tunneling has been observed in atom optics experiments by two
groups. We show that the experimental results are extremely well described by
time-periodic Hamiltonians with momentum quantized in units of the atomic
recoil. The observed tunneling has a well defined period when only two Floquet
states dominate the dynamics. Beat frequencies are observed when three Floquet
states dominate. We find frequencies which match those observed in both
experiments. The dynamical origin of the dominant Floquet states is identified.Comment: Accepted in Physical Review
Narrow structure in the coherent population trapping resonances in rubidium and Rayleigh scattering
The measurement of the coherent-population-trapping (CPT) resonances in
uncoated Rb vacuum cells has shown that the shape of the resonances is
different in different cells. In some cells the resonance has a complex shape -
a narrow Lorentzian structure, which is not power broadened, superimposed on
the power broadened CPT resonance. The results of the performed investigations
on the fluorescence angular distribution are in agreement with the assumption
that the narrow structure is a result of atom interaction with Rayleigh
scattering light. The results are interesting for indication of the vacuum
cleanness of the cells and building of magnetooptical sensors
Metrological characterization of the pulsed Rb clock with optical detection
We report on the implementation and the metrological characterization of a
vapor-cell Rb frequency standard working in pulsed regime. The three main parts
that compose the clock, physics package, optics and electronics, are described
in detail in the paper. The prototype is designed and optimized to detect the
clock transition in the optical domain. Specifically, the reference atomic
transition, excited with a Ramsey scheme, is detected by observing the
interference pattern on a laser absorption signal.
\ The metrological analysis includes the observation and characterization of
the clock signal and the measurement of frequency stability and drift. In terms
of Allan deviation, the measured frequency stability results as low as
, being the averaging time, and
reaches the value of few units of for s, an
unprecedent achievement for a vapor cell clock. We discuss in the paper the
physical effects leading to this result with particular care to laser and
microwave noises transferred to the clock signal. The frequency drift, probably
related to the temperature, stays below per day, and no evidence of
flicker floor is observed.
\ We also mention some possible improvements that in principle would lead to
a clock stability below the level at 1 s and to a drift of few units
of per day
Isolated bilateralabducent nerve palsy dueto a spontaneous left-sidedural carotid cavernousfistula Type Barrow C
Nonlinear magneto-optical resonances at D1 excitation of 85Rb and 87Rb in an extremely thin cell
Nonlinear magneto-optical resonances have been measured in an extremely thin
cell (ETC) for the D1 transition of rubidium in an atomic vapor of natural
isotopic composition. All hyperfine transitions of both isotopes have been
studied for a wide range of laser power densities, laser detunings, and ETC
wall separations. Dark resonances in the laser induced fluorescence (LIF) were
observed as expected when the ground state total angular momentum F_g was
greater than or equal to the excited state total angular momentum F_e. Unlike
the case of ordinary cells, the width and contrast of dark resonances formed in
the ETC dramatically depended on the detuning of the laser from the exact
atomic transition. A theoretical model based on the optical Bloch equations was
applied to calculate the shapes of the resonance curves. The model averaged
over the contributions from different atomic velocity groups, considered all
neighboring hyperfine transitions, took into account the splitting and mixing
of magnetic sublevels in an external magnetic field, and included a detailed
treatment of the coherence properties of the laser radiation. Such a
theoretical approach had successfully described nonlinear magneto-optical
resonances in ordinary vapor cells. Although the values of certain model
parameters in the ETC differed significantly from the case of ordinary cells,
the same physical processes were used to model both cases. However, to describe
the resonances in the ETC, key parameters such as the transit relaxation rate
and Doppler width had to be modified in accordance with the ETC's unique
features. Agreement between the measured and calculated resonance curves was
satisfactory for the ETC, though not as good as in the case of ordinary cells.Comment: v2: substantial changes and expanded theoretical model; 13 pages, 10
figures; accepted for publication in Physical Review
Interdisciplinary, Translational, and Community-Based Participatory Research: Finding a Common Language to Improve Cancer Research
Preventing cancer, downstaging disease at diagnosis, and reducing mortality require that relevant research findings be translated across scientific disciplines and into clinical and public health practice. Interdisciplinary research focuses on using the languages of different scientific disciplines to share techniques and philosophical perspectives to enhance discovery and development of innovations; (i.e., from the âleft endâ of the research continuum). Community-based participatory research (CBPR), whose relevance often is relegated to the âright endâ (i.e., delivery and dissemination) of the research continuum, represents an important means for understanding how many cancers are caused as well as for ensuring that basic science research findings affect cancer outcomes in materially important ways. Effective interdisciplinary research and CBPR both require an ability to communicate effectively across groups that often start out neither understanding each otherâs worldviews nor even speaking the same language. Both demand an ability and willingness to treat individuals from other communities with respect and understanding. We describe the similarities between CBPR and both translational and interdisciplinary research, and then illustrate our points using squamous cell carcinoma of the esophagus as an example of how to deepen understanding and increase relevance by applying techniques of CBPR and interdisciplinary engagement
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