9,576 research outputs found
Inequivalent Leggett-Garg inequalities
It remains an open question how realist view of macroscopic world emerges
from quantum formalism. For testing the macrorealism in quantum domain, an
interesting approach was put forward by Leggett and Garg in , by
formulating a suitable inequality valid for any macrorealistic theory.
Recently, by following the Wigner idea of local realist inequality, a
probabilistic version of standard Leggett-Garg inequalities have also been
proposed. While the Wigner form of local realist inequalities are equivalent to
the two-party, two-measurements and two outcomes CHSH inequalities, in this
paper we provide a generic proof to demonstrate that the Wigner form of
Leggett-Garg inequalities are not only inequivalent to the standard ones but
also stronger than the later. This is demonstrated by quantifying the amount of
disturbance caused by a prior measurement to the subsequent measurements. In
this connection, the relation between LGIs and another formulation of
macrorealism known as no-signaling in time is examined.Comment: Close to the published version. arXiv admin note: text overlap with
arXiv:1705.0993
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In situ formation of catalytically active graphene in ethylene photo-epoxidation.
Ethylene epoxidation is used to produce 2 × 107 ton per year of ethylene oxide, a major feedstock for commodity chemicals and plastics. While high pressures and temperatures are required for the reaction, plasmonic photoexcitation of the Ag catalyst enables epoxidation at near-ambient conditions. Here, we use surface-enhanced Raman scattering to monitor the plasmon excitation-assisted reaction on individual sites of a Ag nanoparticle catalyst. We uncover an unconventional mechanism, wherein the primary step is the photosynthesis of graphene on the Ag surface. Epoxidation of ethylene is then promoted by this photogenerated graphene. Density functional theory simulations point to edge defects on the graphene as the sites for epoxidation. Guided by this insight, we synthesize a composite graphene/Ag/α-Al2O3 catalyst, which accomplishes ethylene photo-epoxidation under ambient conditions at which the conventional Ag/α-Al2O3 catalyst shows negligible activity. Our finding of in situ photogeneration of catalytically active graphene may apply to other photocatalytic hydrocarbon transformations
3D Face Recognition using Significant Point based SULD Descriptor
In this work, we present a new 3D face recognition method based on Speeded-Up
Local Descriptor (SULD) of significant points extracted from the range images
of faces. The proposed model consists of a method for extracting distinctive
invariant features from range images of faces that can be used to perform
reliable matching between different poses of range images of faces. For a given
3D face scan, range images are computed and the potential interest points are
identified by searching at all scales. Based on the stability of the interest
point, significant points are extracted. For each significant point we compute
the SULD descriptor which consists of vector made of values from the convolved
Haar wavelet responses located on concentric circles centred on the significant
point, and where the amount of Gaussian smoothing is proportional to the radii
of the circles. Experimental results show that the newly proposed method
provides higher recognition rate compared to other existing contemporary models
developed for 3D face recognition
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