7,025 research outputs found
Attosecond electronic and nuclear quantum photodynamics of ozone: time-dependent Dyson orbitals and dipole
A nonadiabatic scheme for the description of the coupled electron and nuclear
motions in the ozone molecule was proposed recently. An initial coherent
nonstationary state was prepared as a superposition of the ground state and the
excited Hartley band. In this situation neither the electrons nor the nuclei
are in a stationary state. The multiconfiguration time dependent Hartree method
was used to solve the coupled nuclear quantum dynamics in the framework of the
adiabatic separation of the time-dependent Schr\"odinger equation. The
resulting wave packet shows an oscillation of the electron density between the
two chemical bonds. As a first step for probing the electronic motion we
computed the time-dependent molecular dipole and the Dyson orbitals. The latter
play an important role in the explanation of the photoelectron angular
distribution. Calculations of the Dyson orbitals are presented both for the
time-independent as well as the time-dependent situations. We limited our
description of the electronic motion to the Franck-Condon region only due to
the localization of the nuclear wave packets around this point during the first
5-6 fs
Spatial correlations in hexagons generated via a Kerr nonlinearity
We consider the hexagonal pattern forming in the cross-section of an optical
beam produced by a Kerr cavity, and we study the quantum correlations
characterizing this structure. By using arguments related to the symmetry
broken by the pattern formation, we identify a complete scenario of six-mode
entanglement. Five independent phase quadratures combinations, connecting the
hexagonal modes, are shown to exhibit sub-shot-noise fluctuations. By means of
a non-linear quantum calculation technique, quantum correlations among the mode
photon numbers are demonstrated and calculated.Comment: ReVTeX file, 20 pages, 7 eps figure
From Natural Woods to High Density Materials: An Ecofriendly Approach
Densified wood are a woody materials which an increase in density and mechanical properties. The
materials obtained in this work, using less pollutant reagents, showed an increase in density from 200% to 400%. The characterizations determine the chemical and structural change compositions after every step. These characterizations showed how different woods have comparable densities and final mechanical properties (+300% the initial one) after densification process
Generation of two-color polarization-entangled optical beams with a self-phase-locked two-crystal Optical Parametric Oscillator
A new device to generate polarization-entangled light in the continuous
variable regime is introduced. It consists of an Optical Parametric Oscillator
with two type-II phase-matched non-linear crystals orthogonally oriented,
associated with birefringent elements for adjustable linear coupling. We give
in this paper a theoretical study of its classical and quantum properties. It
is shown that two optical beams with adjustable frequencies and well-defined
polarization can be emitted. The Stokes parameters of the two beams are
entangled. The principal advantage of this setup is the possibility to directly
generate polarization entangled light without the need of mixing four modes on
beam splitters as required in current experimental setups. This device opens
new directions for the study of light-matter interfaces and generation of
multimode non-classical light and higher dimensional phase space
Nature of light correlations in ghost imaging
We investigate the nature of correlations in Gaussian light sources used for
ghost imaging. We adopt methods from quantum information theory to distinguish
genuinely quantum from classical correlations. Combining a microscopic analysis
of speckle-speckle correlations with an effective coarse-grained description of
the beams, we show that quantum correlations exist even in `classical'-like
thermal light sources, and appear relevant for the implementation of ghost
imaging in the regime of low illumination. We further demonstrate that the
total correlations in the thermal source beams effectively determine the
quality of the imaging, as quantified by the signal-to-noise ratio.Comment: 12 pages, 5 figures. To appear in Scientific Reports (NPG
Longitudinal coherence in thermal ghost imaging
We show theoretically and experimentally that lensless ghost imaging with thermal light is fully interpretable in terms of classical statistical optics. The disappearance of the ghost image when the object and the reference planes are located at different distances from the source is due to the fading out of the intensity-intensity cross correlation between the two planes. Thus the visibility and the resolution of the ghost image are determined by the longitudinal coherence of the speckle beam, and no quantum explanation is necessary.We show theoretically and experimentally that lensless ghost imaging with thermal light is fully interpretable in terms of classical statistical optics. The disappearance of the ghost image when the object and the reference planes are located at different distances from the source is due to the fading out of the intensity-intensity cross correlation between the two planes. Thus the visibility and the resolution of the ghost image are determined by the longitudinal coherence of the speckle beam, and no quantum explanation is necessary. \ua9 2008 American Institute of Physics
Investigation of the preparation of materials in space. Task 4 - Field management for weightless containerless processing Quarterly progress report, 22 Aug. - 31 Oct. 1969
Weightless containerless processing for space, electromagnetic position control, force measurements and techniques, and hydrodynamic
Polarization quantum properties in type-II Optical Parametric Oscillator below threshold
We study the far field spatial distribution of the quantum fluctuations in
the transverse profile of the output light beam generated by a type II Optical
Parametric Oscillator below threshold, including the effects of transverse
walk-off. We study how quadrature field correlations depend on the
polarization. We find spatial EPR entanglement in quadrature-polarization
components: For the far field points not affected by walk-off there is almost
complete noise suppression in the proper quadratures difference of any
orthogonal polarization components. We show the entanglement of the state of
symmetric intense, or macroscopic, spatial light modes. We also investigate
nonclassical polarization properties in terms of the Stokes operators. We find
perfect correlations in all Stokes parameters measured in opposite far field
points in the direction orthogonal to the walk-off, while locally the field is
unpolarized and we find no polarization squeezing.Comment: 16 pages, 18 figure
Acceleration with Self-Injection for an All-Optical Radiation Source at LNF
We discuss a new compact gamma-ray source aiming at high spectral density, up
to two orders of magnitude higher than currently available bremsstrahlung
sources, and conceptually similar to Compton Sources based on conventional
linear accelerators. This new source exploits electron bunches from
laser-driven electron acceleration in the so-called self-injection scheme and
uses a counter-propagating laser pulse to obtain X and gamma-ray emission via
Thomson/Compton scattering. The proposed experimental configuration inherently
provides a unique test-bed for studies of fundamental open issues of
electrodynamics. In view of this, a preliminary discussion of recent results on
self-injection with the FLAME laser is also given.Comment: 8 pages, 10 figures, 44 references - Channeling 2012 conferenc
Team-maxmin equilibrium: Efficiency bounds and algorithms
The Team-maxmin equilibrium prescribes the optimal strategies for a team of rational players sharing the same goal and without the capability of correlating their strategies in strategic games against an adversary. This solution concept can capture situations in which an agent controls multiple resources-corresponding to the team members-that cannot communicate. It is known that such equilibrium always exists and it is unique (except degenerate cases) and these properties make it a credible solution concept to be used in real-world applications, especially in security scenarios. Nevertheless, to the best of our knowledge, the Team-maxmin equilibrium is almost completely unexplored in the literature. In this paper, we investigate bounds of (in) efficiency of the Team-maxmin equilibrium w.r.t. the Nash equilibria and w.r.t. the Maxmin equilibrium when the team members can play correlated strategies. Furthermore, we study a number of algorithms to find and/or approximate an equilibrium, discussing their theoretical guarantees and evaluating their performance by using a standard testbed of game instances
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