57 research outputs found
Entanglement of Conceptual Entities in Quantum Model Theory (QMod)
We have recently elaborated 'Quantum Model Theory' (QMod) to model situations
where the quantum effects of contextuality, interference, superposition,
entanglement and emergence, appear without the entities giving rise to these
situations having necessarily to be of microscopic nature. We have shown that
QMod models without introducing linearity for the set of the states. In this
paper we prove that QMod, although not using linearity for the state space,
provides a method of identification for entangled states and an intuitive
explanation for their occurrence. We illustrate this method for entanglement
identification with concrete examples
Tailoring surface topographies on solids with Mid-IR femtosecond laser pulses
Irradiation of solids with ultrashort pulses using laser sources in the
mid-infrared (mid-IR) spectral region is a yet predominantly unexplored field
that opens broad possibilities for efficient and precise surface texturing for
a wide range of applications. In the present work, we investigate both
experimentally and theoretically the impact of laser sources on the generation
of surface modification related effects and on the subsequent surface
patterning of metallic and semiconducting materials. Through a parametric study
we correlate the mid-IR pulsed laser parameters with the onset of material
damage and the formation of a variety of periodic surface structures at a laser
wavelength of {\lambda}L=3200 nm and a pulse duration of {\tau}p=45 fs. Results
for nickel and silicon indicate that the produced topographies comprise both
high and low spatial frequency induced periodic structures, similar to those
observed at lower wavelengths, while groove formation is absent. The
investigation of the damage thresholds suggests the incorporation of nonlinear
effects generated from three-photon-assisted excitation (for silicon) and the
consideration of the role of the non-thermal excited electron population (for
nickel) at very short pulse durations. The results demonstrate the potential of
surface structuring with mid-IR pulses, which can constitute a systematic novel
engineering approach with strong fields at long-wavelength spectral regions
that can be used for advanced industrial laser applications
Does The 3N-Force Have A Hard Core?
The meson-nucleon dynamics that generates the hard core of the RuhrPot
two-nucleon interaction is shown to vanish in the irreducible 3N force. This
result indicates a small 3N force dominated by conventional light
meson-exchange dynamics and holds for an arbitrary meson-theoretic Lagrangian.
The resulting RuhrPot 3N force is defined in the appendix. A completely
different result is expected when the Tamm-Dancoff/Bloch-Horowitz procedure is
used to define the NN and 3N potentials. In that approach, (e.g. full Bonn
potential) both the NN {\it and} 3N potentials contain non-vanishing
contributions from the coherent sum of meson-recoil dynamics and the
possibility of a large hard core requiring explicit calculation cannot be ruled
out.Comment: 16 pages REVTeX + 3 ps fig
Single-Shot Electron Imaging of Dopant-Induced Nanoplasmas
We present single-shot electron velocity-map images of nanoplasmas generated from doped helium nanodroplets and neon clusters by intense near-infrared and mid-infrared laser pulses. We report a large variety of signal types, most crucially depending on the cluster size. The common feature is a two-component distribution for each single-cluster event: a bright inner part with nearly circular shape corresponding to electron energies up to a few eV, surrounded by an extended background of more energetic electrons. The total counts and energy of the electrons in the inner part are strongly correlated and follow a simple power-law dependence. Deviations from the circular shape of the inner electrons observed for neon clusters and large helium nanodroplets indicate non-spherical shapes of the neutral clusters. The dependence of the measured electron energies on the extraction voltage of the spectrometer indicates that the evolution of the nanoplasma is significantly affected by the presence of an external electric field. This conjecture is confirmed by molecular dynamics simulations, which reproduce the salient features of the experimental electron spectra.The authors are grateful for financial support from the Deutsche Forschungsgemeinschaft (DFG) within the
project MU 2347/12-1 and STI 125/22-2 in the frame of the Priority Programme 1840 âQuantum Dynamics
in Tailored Intense Fieldsâ, from the Carlsberg Foundation and the SPARC Programme, MHRD, India. The
ELI-ALPS Project (GINOP-2.3.6-15-2015-00001) is supported by the European Union and co-financed by
the European Regional Development Fund. AH is grateful for financial support from the Basque
Government (Project Reference No. IT1254-19) and from the Spanish Ministerio de Economia y
Competividad (Reference No. CTQ2015-67660-P). Computational and manpower support provided by
IZO-SGI SG Iker of UPV/EHU and European funding (EDRF and ESF) is gratefully acknowledged
Consistent off-shell vertex and nucleon self-energy
We present a consistent calculation of half-off-shell form factors in the
pion-nucleon vertex and the nucleon self-energy. Numerical results are
presented. Near the on-shell point the pion-nucleon vertex is dominated by the
pseudovector coupling, while at large nucleon invariant masses we find a
sizable pseudoscalar admixture.Comment: 23 pages, 7 figures, REVTeX, submitted to Phys. Rev. C, replaced with
corrected versio
The hemispherical asymmetry from a scale-dependent inflationary bispectrum
If the primordial bispectrum is sufficiently large then the CMB hemispherical asymmetry may be explained by a large-scale mode of exceptional amplitude which perturbs the zeta two-point function. We extend previous calculations, which were restricted to one- or two-source scenarios, by providing a method to compute the response of the two-point function in any model yielding a 'local-like' bispectrum. In general, this shows that it is not the reduced bispectrum fNL which sources the amplitude and scale-dependence of the mode coupling but rather a combination of 'response functions'. We discuss why it is difficult to construct successful scenarios and enumerate the fine-tunings which seem to be required. Finally, we exhibit a concrete model which can be contrived to match the observational constraints and show that to a Planck-like experiment it would appear to have |fNL-local| ~ |fNL-equi| ~ |fNL-ortho| ~ 1. Therefore, contrary to previous analyses, we conclude that it is possible to generate the asymmetry while respecting observational constraints on the bispectrum and low-ell multipoles even without tuning our location on the long-wavelength mode
Imprint of DES superstructures on the cosmic microwave background
Small temperature anisotropies in the cosmic microwave background (CMB) can be sourced by density perturbations via the late-time integrated Sachs-Wolfe (ISW) effect. Large voids and superclusters are excellent environments to make a localized measurement of this tiny imprint. In some cases excess signals have been reported. We probed these claims with an independent data set, using the first year data of the Dark Energy Survey (DES) in a different footprint, and using a different superstructure finding strategy. We identified 52 large voids and 102 superclusters at redshifts 0.2 < z < 0.65. We used the Jubilee simulation to a priori evaluate the optimal ISW measurement configuration for our compensated top-hat filtering technique, and then performed a stacking measurement of the CMB temperature field based on the DES data. For optimal configurations, we detected a cumulative cold imprint of voids with DeltaTf â -5.0 ± 3.7 muK and a hot imprint of superclusters DeltaTf â 5.1 ± 3.2 muK; this is Ë1.2sigma higher than the expected |DeltaTf| â 0.6 muK imprint of such superstructures in Lambda cold dark matter (LambdaCDM). If we instead use an a posteriori selected filter size (R/Rv = 0.6), we can find a temperature decrement as large as DeltaTf â -9.8 ± 4.7 muK for voids, which is Ë2sigma above LambdaCDM expectations and is comparable to previous measurements made using Sloan Digital Sky Survey superstructure data
Scale-dependent non-Gaussianity and the CMB power asymmetry
We introduce an alternative parametrisation for the scale dependence of the nonâlinearity parameter fNL in quasi-local models of nonâGaussianity. Our parametrisation remains valid when fNL changes sign, unlike the commonly adopted power law ansatz fNL(k) â knfNL. We motivate our alternative parametrisation by appealing to the self-interacting curvaton scenario, and as an application, we apply it to the CMB power asymmetry. Explaining the power asymmetry requires a strongly scale dependent non-Gaussianity. We show that regimes of model parameter space where fNL is strongly scale dependent are typically associated with a large gNL and quadrupolar power asymmetry, which can be ruled out by existing observational constraints
A CMB Gibbs sampler for localized secondary anisotropies
As well as primary fluctuations, CMB temperature maps contain a wealth of additional information in the form of secondary anisotropies. Secondary effects that can be identified with individual objects, such as the thermal and kinetic Sunyaev-Zel'dovich (SZ) effects due to galaxy clusters, are difficult to unambiguously disentangle from foreground contamination and the primary CMB however. We develop a Bayesian formalism for rigorously characterising anisotropies that are localised on the sky, taking the TSZ and KSZ effects as an example. Using a Gibbs sampling scheme, we are able to efficiently sample from the joint posterior distribution for a multi-component model of the sky with many thousands of correlated physical parameters. The posterior can then be exactly marginalised to estimate properties of the secondary anisotropies, fully taking into account degeneracies with the other signals in the CMB map. We show that this method is computationally tractable using a simple implementation based on the existing Commander component separation code, and also discuss how other types of secondary anisotropy can be accommodated within our framework
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