642 research outputs found
Highly versatile atomic micro traps generated by multifrequency magnetic field modulation
We propose the realization of custom-designed adiabatic potentials for cold
atoms based on multimode radio frequency radiation in combination with static
inhomogeneous magnetic fields. For example, the use of radio frequency combs
gives rise to periodic potentials acting as gratings for cold atoms. In strong
magnetic field gradients the lattice constant can be well below 1 micrometer.
By changing the frequencies of the comb in time the gratings can easily be
propagated in space, which may prove useful for Bragg scattering atomic matter
waves. Furthermore, almost arbitrarily shaped potential are possible such as
disordered potentials on a scale of several 100 nm or lattices with a spatially
varying lattice constant. The potentials can be made state selective and, in
the case of atomic mixtures, also species selective. This opens new
perspectives for generating tailored quantum systems based on ultra cold single
atoms or degenerate atomic and molecular quantum gases.Comment: 12 pages, 6 figure
Probing quantum phases of ultracold atoms in optical lattices by transmission spectra in cavity QED
Studies of ultracold atoms in optical lattices link various disciplines,
providing a playground where fundamental quantum many-body concepts, formulated
in condensed-matter physics, can be tested in much better controllable atomic
systems, e.g., strongly correlated phases, quantum information processing.
Standard methods to measure quantum properties of Bose-Einstein condensates
(BECs) are based on matter-wave interference between atoms released from traps
which destroys the system. Here we propose a nondestructive method based on
optical measurements, and prove that atomic statistics can be mapped on
transmission spectra of a high-Q cavity. This can be extremely useful for
studying phase transitions between Mott insulator and superfluid states, since
various phases show qualitatively distinct light scattering. Joining the
paradigms of cavity quantum electrodynamics (QED) and ultracold gases will
enable conceptually new investigations of both light and matter at ultimate
quantum levels, which only recently became experimentally possible. Here we
predict effects accessible in such novel setups.Comment: 6 pages, 3 figure
Fermat-linked relations for the Boubaker polynomial sequences via Riordan matrices analysis
The Boubaker polynomials are investigated in this paper. Using Riordan
matrices analysis, a sequence of relations outlining the relations with
Chebyshev and Fermat polynomials have been obtained. The obtained expressions
are a meaningful supply to recent applied physics studies using the Boubaker
polynomials expansion scheme (BPES).Comment: 12 pages, LaTe
Towards surface quantum optics with Bose-Einstein condensates in evanescent waves
We present a surface trap which allows for studying the coherent interaction
of ultracold atoms with evanescent waves. The trap combines a magnetic Joffe
trap with a repulsive evanescent dipole potential. The position of the magnetic
trap can be controlled with high precision which makes it possible to move
ultracold atoms to the surface of a glass prism in a controlled way. The
optical potential of the evanescent wave compensates for the strong attractive
van der Waals forces and generates a potential barrier at only a few hundred
nanometers from the surface. The trap is tested with Rb Bose-Einstein
condensates (BEC), which are stably positioned at distances from the surfaces
below one micrometer
The SCIDOTS Project: Evidence of benefits of an integrated tobacco cessation intervention in tuberculosis care on treatment outcomes
<p>Abstract</p> <p>Background</p> <p>There is substantial evidence to support the association between tuberculosis (TB) and tobacco smoking and that the smoking-related immunological abnormalities in TB are reversible within six weeks of cessation. Therefore, connecting TB and tobacco cessation interventions may produce significant benefits and positively impact TB treatment outcomes. However, no study has extensively documented the evidence of benefits of such integration. SCIDOTS Project is a study from the context of a developing nation aimed to determine this.</p> <p>Methods</p> <p>An integrated TB-tobacco intervention was provided by trained TB directly observed therapy short-course (DOTS) providers at five chest clinics in Malaysia. The study was a prospective non-randomized controlled intervention using quasi-experimental design. Using Transtheoretical Model approach, 120 eligible participants who were current smokers at the time of TB diagnosis were assigned to either of two treatment groups: conventional TB DOTS plus smoking cessation intervention (integrated intervention or SCIDOTS group) or conventional TB DOTS alone (comparison or DOTS group). At baseline, newly diagnosed TB patients considering quitting smoking within the next 30 days were placed in the integrated intervention group, while those who were contemplating quitting were assigned to the comparison group. Eleven sessions of individualized cognitive behavioral therapy with or without nicotine replacement therapy were provided to each participant in the integrated intervention group. The impacts of the novel approach on biochemically validated smoking cessation and TB treatment outcomes were measured periodically as appropriate.</p> <p>Results</p> <p>A linear effect on both 7-day point prevalence abstinence and continuous abstinence was observed over time in the intervention group. At the end of 6 months, patients who received the integrated intervention had significantly higher rate of success in quitting smoking when compared with those who received the conventional TB treatment alone (77.5% vs. 8.7%; p < 0.001). Furthermore, at the end of TB treatment (6 months or later), there were significantly higher rates of treatment default (15.2% vs. 2.5%; p = 0.019) and treatment failure (6.5% vs. 0%; p = 0.019) in the DOTS group than in the SCIDOTS group.</p> <p>Conclusion</p> <p>This study provides evidence that connecting TB-tobacco treatment strategy is significant among TB patients who are smokers. The findings suggest that the integrated approach may be beneficial and confer advantages on short-term outcomes and possibly on future lung health of TB patients who quit smoking. This study may have important implications on health policy and clinical practice related to TB management among tobacco users.</p
Cooperative coupling of ultracold atoms and surface plasmons
Cooperative coupling between optical emitters and light fields is one of the
outstanding goals in quantum technology. It is both fundamentally interesting
for the extraordinary radiation properties of the participating emitters and
has many potential applications in photonics. While this goal has been achieved
using high-finesse optical cavities, cavity-free approaches that are broadband
and easy to build have attracted much attention recently. Here we demonstrate
cooperative coupling of ultracold atoms with surface plasmons propagating on a
plane gold surface. While the atoms are moving towards the surface they are
excited by an external laser pulse. Excited surface plasmons are detected via
leakage radiation into the substrate of the gold layer. A maximum Purcell
factor of is reached at an optimum distance of
from the surface. The coupling leads to the observation of
a Fano-like resonance in the spectrum.Comment: 9 pages, 4 figure
Dynamical Coupling between a Bose-Einstein Condensate and a Cavity Optical Lattice
A Bose-Einstein condensate is dispersively coupled to a single mode of an
ultra-high finesse optical cavity. The system is governed by strong
interactions between the atomic motion and the light field even at the level of
single quanta. While coherently pumping the cavity mode the condensate is
subject to the cavity optical lattice potential whose depth depends nonlinearly
on the atomic density distribution. We observe bistability already below the
single photon level and strong back-action dynamics which tunes the system
periodically out of resonance.Comment: 5 pages, 4 figure
Opto-mechanical measurement of micro-trap via nonlinear cavity enhanced Raman scattering spectrum
High-gain resonant nonlinear Raman scattering on trapped cold atoms within a
high-fineness ring optical cavity is simply explained under a nonlinear
opto-mechanical mechanism, and a proposal using it to detect frequency of
micro-trap on atom chip is presented. The enhancement of scattering spectrum is
due to a coherent Raman conversion between two different cavity modes mediated
by collective vibrations of atoms through nonlinear opto-mechanical couplings.
The physical conditions of this technique are roughly estimated on Rubidium
atoms, and a simple quantum analysis as well as a multi-body semiclassical
simulation on this nonlinear Raman process is conducted.Comment: 7 pages, 2 figure
Air pollution exposure during pregnancy and childhood autistic traits in four European population-based cohort studies : the ESCAPE project
Background: Prenatal exposure to air pollutants has been suggested as a possible etiologic factor
for the occurrence of autism spectrum disorder.
Objectives: We aimed to assess whether prenatal air pollution exposure is associated with
childhood autistic traits in the general population.
Methods: Ours was a collaborative study of four European population-based birth/child cohorts—
CATSS (Sweden), Generation R (the Netherlands), GASPII (Italy), and INMA (Spain). Nitrogen
oxides (NO2, NOx) and particulate matter (PM) with diameters of ≤ 2.5 μm (PM2.5), ≤ 10 μm
(PM10), and between 2.5 and 10 μm (PMcoarse), and PM2.5 absorbance were estimated for birth
addresses by land-use regression models based on monitoring campaigns performed between 2008
and 2011. Levels were extrapolated back in time to exact pregnancy periods. We quantitatively
assessed autistic traits when the child was between 4 and 10 years of age. Children were classified
with autistic traits within the borderline/clinical range and within the clinical range using
validated cut-offs. Adjusted cohort-specific effect estimates were combined using random-effects
meta-analysis.
Results: A total of 8,079 children were included. Prenatal air pollution exposure was not associated
with autistic traits within the borderline/clinical range (odds ratio = 0.94; 95% CI: 0.81, 1.10
per each 10‑μg/m3 increase in NO2 pregnancy levels). Similar results were observed in the different
cohorts, for the other pollutants, and in assessments of children with autistic traits within the
clinical range or children with autistic traits as a quantitative score.
Conclusions: Prenatal exposure to NO2 and PM was not associated with autistic traits in children
from 4 to 10 years of age in four European population-based birth/child cohort studies.NonePublishe
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