85,163 research outputs found
Space charge measurement in polymer insulated power cables using flat ground electrode PEA
Data processing methods used to accurately determine the space charge and electric stress distributions in DC power cables using the pulsed electroacoustic (PEA) system are described. Due to the coaxial geometry and the thick-walled insulation of highvoltage cables, factors such as divergence, attenuation and dispersion of the propagated acoustic pressure wave in the PEA can strongly influence the resultant measurements. These factors are taken into account ensuring accurate measurements to be made. Most importantly, a method is presented to determine the electric stress profile across the insulation due to both the divergent applied field and that as a consequence of trapped charge in the bulk of the insulating material. Results of spacecharge measurements and the corresponding derived electric stress distributions in XLPE DC cables are presented
New classes of topological crystalline insulators with unpinned surface Dirac cones
We theoretically predict two new classes of three-dimensional topological
crystalline insulators (TCIs), which have an odd number of unpinned surface
Dirac cones protected by crystal symmetries. The first class is protected by a
single glide plane symmetry; the second class is protected by a composition of
a twofold rotation and time-reversal symmetry. Both classes of TCIs are
characterized by a quantized Berry phase associated with surface states
and a topological invariant associated with the bulk bands. In the
presence of disorder, these TCI surface states are protected against
localization by the average crystal symmetries, and exhibit critical
conductivity in the universality class of the quantum Hall plateau transition.
These new TCIs exist in time-reversal-breaking systems with or without
spin-orbital coupling, and their material realizations are discussed.Comment: 4 pages plus supplementary material
Testing violation of the Leggett-Garg-type inequality in neutrino oscillations of the Daya Bay experiment
The Leggett-Garg inequality (LGI), derived under the assumption of realism,
acts as the temporal Bell's inequality. It is studied in electromagnetic and
strong interaction like photonics, superconducting qu-bits and nuclear spin.
Until the weak interaction two-state oscillations of neutrinos affirmed the
violation of Leggett-Garg-type inequalities (LGtI). We make an empirical test
for the deviation of experimental results with the classical limits by
analyzing the survival probability data of reactor neutrinos at a distinct
range of baseline dividing energies, as an analog to a single neutrino detected
at different time. A study of the updated data of Daya-Bay experiment
unambiguously depicts an obvious cluster of data over the classical bound of
LGtI and shows a significance of the violation of them.Comment: 11 pages, 6 figure
Hypergeometric States and Their Nonclassical Properties
`Hypergeometric states', which are a one-parameter generalization of binomial
states of the single-mode quantized radiation field, are introduced and their
nonclassical properties are investigated. Their limits to the binomial states
and to the coherent and number states are studied. The ladder operator
formulation of the hypergeometric states is found and the algebra involved
turns out to be a one-parameter deformation of algebra. These states
exhibit highly nonclassical properties, like sub-Poissonian character,
antibunching and squeezing effects. The quasiprobability distributions in phase
space, namely the and the Wigner functions are studied in detail. These
remarkable properties seem to suggest that the hypergeometric states deserve
further attention from theoretical and applicational sides of quantum optics.Comment: 17 pages, latex, 7 EPS figure
Negative Binomial and Multinomial States: probability distributions and coherent states
Following the relationship between probability distribution and coherent
states, for example the well known Poisson distribution and the ordinary
coherent states and relatively less known one of the binomial distribution and
the coherent states, we propose ``interpretation'' of and
coherent states ``in terms of probability theory''. They will be
called the ``negative binomial'' (``multinomial'') ``states'' which correspond
to the ``negative'' binomial (multinomial) distribution, the non-compact
counterpart of the well known binomial (multinomial) distribution. Explicit
forms of the negative binomial (multinomial) states are given in terms of
various boson representations which are naturally related to the probability
theory interpretation. Here we show fruitful interplay of probability theory,
group theory and quantum theory.Comment: 24 pages, latex, no figure
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