207 research outputs found
Helicity correlations of vector bosons
We calculate the helicity and polarization correlation functions in the
Einstein-Podolsky-Rosen-type experiments with relativistic vector bosons. We
show that the linear polarization correlation function in the appriopriately
chosen state in the massless limit is the same as the correlation function in
the scalar two-photon state. We show also that the polarization correlation
function violate the Clauser-Horne-Shimony-Holt inequality and that the degree
of this violation can increase with the particle momentum.Comment: 8 pages, 3 figure
Urinary bladder diverticulum as an unusual content of the inguinal canal
The inguinal urinary bladder hernia is a rare pathology observed mostly in males. A new case of asymptomatic reducible acquired inguinal hernia was revealed in a 54-year-old male during computed tomography (CT) undertaken for oncological follow-up. The right nephrectomy was previously performed due to clear cell carcinoma. The hernia was not visible on the CT 6 months before and on ultrasound performed after voiding. Slight herniation with a wide invagination of transversalis fascia but with empty bladder was seen on CT 4 months after the initial detection of hernia
Effect of growth pressure on coalescence thickness and crystal quality of GaN deposited on 4H-SiC
Cataloged from PDF version of article.The influence of growth pressure on the coalescence thickness and the crystal quality of GaN deposited on 4H-SiC by low pressure metalorganic vapor phase epitaxy was studied. It was shown that growth pressure has an impact on the surface roughness of epilayers and their crystal quality. GaN coalescence thicknesses were determined for the investigated growth pressures. The GaN layers were characterized by AFM and HRXRD measurements. HEMT structures were also fabricated and characterized. Among the growth pressures studied, 50, 125 and 200 mbar, 200 mbar was found to be most suitable for GaN/SiC epitaxy. (C) 2010 Elsevier B.V. All rights reserved
Unstable particles as open quantum systems
We present the probability preserving description of the decaying particle
within the framework of quantum mechanics of open systems taking into account
the superselection rule prohibiting the superposition of the particle and
vacuum. In our approach the evolution of the system is given by a family of
completely positive trace preserving maps forming one-parameter dynamical
semigroup. We give the Kraus representation for the general evolution of such
systems which allows one to write the evolution for systems with two or more
particles. Moreover, we show that the decay of the particle can be regarded as
a Markov process by finding explicitly the master equation in the Lindblad
form. We also show that there are remarkable restrictions on the possible
strength of decoherence.Comment: 11 pp, 2 figs (published version
Subconcussive Head Impact Results in a Unique Circulating Exosomal MicroRNA Signature
Please see the pdf version of the abstract
Destruction of states in quantum mechanics
A description of destruction of states on the grounds of quantum mechanics
rather than quantum field theory is proposed. Several kinds of maps called
supertraces are defined and used to describe the destruction procedure. The
introduced algorithm can be treated as a supplement to the von Neumann-Lueders
measurement. The discussed formalism may be helpful in a description of EPR
type experiments and in quantum information theory.Comment: 14 pp, 1 eps figure, LaTeX2e using iopart class. Final version, will
be published in J. Phys. A: Math. Ge
AlGaN quadruple-band photodetectors
Quadruple back-illuminated ultraviolet metal-semiconductor-metal photodetectors with four different spectral responsivity bands were demonstrated. The average of the full-width at half-maximum (FWHM) of the quantum efficiency peaks was 9.98 nm. © 2009 IEEE
Integrated AlGaN quadruple-band ultraviolet photodetectors
Monolithically integrated quadruple back-illuminated ultraviolet metalsemiconductormetal photodetectors with four different spectral responsivity bands were demonstrated on each of two different Al xGa 1-xN heterostructures. The average of the full-width at half-maximum (FWHM) of the quantum efficiency peaks was 18.15nm for sample A, which incorporated five 1000nm thick epitaxial layers. In comparison, the average FWHM for sample B was 9.98 nm, which incorporated nine 500nm thick epitaxial layers. © 2012 IOP Publishing Ltd
Wigner's little group and Berry's phase for massless particles
The ``little group'' for massless particles (namely, the Lorentz
transformations that leave a null vector invariant) is isomorphic to
the Euclidean group E2: translations and rotations in a plane. We show how to
obtain explicitly the rotation angle of E2 as a function of and we
relate that angle to Berry's topological phase. Some particles admit both signs
of helicity, and it is then possible to define a reduced density matrix for
their polarization. However, that density matrix is physically meaningless,
because it has no transformation law under the Lorentz group, even under
ordinary rotations.Comment: 4 pages revte
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