1,829 research outputs found
Generation and detection of axions using guided structures
We propose a new experimental technique to generate and detect axions in the
lab with a good experimental sensitivity over a broad axion mass range. The
scheme relies on using laser-based four-wave mixing, which is mediated by the
hypothetical axion field. Intense pump and Stokes laser beams that are confined
to a waveguide (i.e., for example, an optical fiber) with appropriately chosen
frequencies resonantly drive axion generation. Under such a geometry, we
predict the existence of guided axion waves, which we refer to as "axitons".
These are solutions of the axion Klein-Gordon field equation that are spatially
guided by the profiles of the driving pump and Stokes laser beams. These guided
axitons can then couple to a nearby fiber and mix with another laser, affecting
the propagation of a probe laser beam. A key advantage of the scheme is that
the mass range of the hypothetical axion can be scanned by varying the
frequencies of the pump and the Stokes laser beams. We predict that, using
reasonable parameters, the technique will be able to detect axions in the mass
range eV eV with a sensitivity at the level of
GeV for the axion-photon coupling constant
Towards smaller family size in Egypt, Morocco and Turkey: overall change over time or socio-economic compositional effect?
The whole region of the South and East Mediterranean exhibits a profound fertility transition with marked differences in the pace of fertility declines among the countries. The authors choose three representative countries: Egypt, Morocco and Turkey. Determinants of the propensity towards smaller family size are investigated as scrutinizing the development in the pattern of third births, which represents the critical step in the transitional process for these countries. The authors are particularly interested in verifying whether the decline of higher-order births is significantly driven by an overall societal change over time or by compositional change over different socio-economic segments of the female population. Evidence is found that overall societal changes have mainly driven the decline in large family size, though, to a much lesser extent, compositional changes are important too.Egypt, Morocco, Turkey, childbearing, family size, fertility decline
Rabi flopping between ground and Rydberg states with dipole-dipole atomic interactions
We demonstrate Rabi flopping of small numbers of atoms between
ground and Rydberg states with . Coherent population oscillations are
observed for single atom flopping, while the presence of two or more atoms
decoheres the oscillations. We show that these observations are consistent with
van der Waals interactions of Rydberg atoms.Comment: 4 pages, 6 figure
Spectral-discrete solitons and localization in frequency space
We report families of discrete optical solitons in frequency space, or
spectral-discrete solitons existing in a dispersive Raman medium, where
individual side-bands are coupled by coherence. The associated time-domain
patterns correspond to either trains of ultrashort pulses, or weakly modulated
waves. We describe the physics behind the spectral localization and study
soliton bifurcations, stability and dynamics.Comment: 4 pages, 4 figures, submitted to Opt. Let
Refractive Index Enhancement with Vanishing Absorption in an Atomic Vapor
We report a proof-of-principle experiment where the refractive index of an
atomic vapor is enhanced while maintaining vanishing absorption of the beam.
The key idea is to drive alkali atoms in a vapor with appropriate control
lasers and induce a gain resonance and an absorption resonance for a probe beam
in a two-photon Raman configuration. The strength and the position of these two
resonances can be manipulated by changing the parameters of the control lasers.
By using the interference between these two resonances, we obtain an enhanced
refractive index without an increase in the absorption.Comment: 11 pages, 4 figure
Quantum Simulator Based on the Paraxial Wave Equation
We propose a paraxial quantum simulator that requires only widely available
optical fibers or metamaterials. Such a simulator would facilitate
cost-effective quantum simulation without specialized techniques. We show
theoretically that the method accurately simulates quantum dynamics and quantum
effects for an example system, which invites extension of the method to
many-body systems using nonlinear optical elements and implementation of the
paraxial quantum simulator to extend access to quantum computation and
prototype quantum parity-time reversal () symmetric technologies
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