18,383 research outputs found
Star-shaped Local Density of States around Vortices in a Type II Superconductor
The electronic structure of vortices in a type II superconductor is analyzed
within the quasi-classical Eilenberger framework. The possible origin of a
sixfold ``star'' shape of the local density of states, observed by scanning
tunneling microscope experiments on NbSe, is examined in the light of the
three effects; the anisotropic pairing, the vortex lattice, and the anisotropic
density of states at the Fermi surface. Outstanding features of split parallel
rays of this star are well explained in terms of an anisotropic -wave
pairing. This reveals a rich internal electronic structure associated with a
vortex core.Comment: 4 pages, REVTeX, 3 figures available upon reques
Hidden assumptions in the derivation of the Theorem of Bell
John Bell's inequalities have already been considered by Boole in 1862. Boole
established a one-to-one correspondence between experimental outcomes and
mathematical abstractions of his probability theory. His abstractions are
two-valued functions that permit the logical operations AND, OR and NOT and are
the elements of an algebra. Violation of the inequalities indicated to Boole an
inconsistency of definition of the abstractions and/or the necessity to revise
the algebra. It is demonstrated in this paper, that a violation of Bell's
inequality by Einstein-Podolsky-Rosen type of experiments can be explained by
Boole's ideas. Violations of Bell's inequality also call for a revision of the
mathematical abstractions and corresponding algebra. It will be shown that this
particular view of Bell's inequalities points toward an incompleteness of
quantum mechanics, rather than to any superluminal propagation or influences at
a distance
Analytical and experimental study of the dynamics of a single-tube counterflow boiler
Experimental and analytical study of dynamics of single tube counterflow boile
Local density of states in the vortex lattice in a type II superconductor
Local density of states (LDOS) in the triangular vortex lattice is
investigated based on the quasi-classical Eilenberger theory. We consider the
case of an isotropic s-wave superconductor with the material parameter
appropriate to NbSe_2. At a weak magnetic field, the spatial variation of the
LDOS shows cylindrical structure around a vortex core. On the other hand, at a
high field where the core regions substantially overlap each other, the LDOS is
sixfold star-shaped structure due to the vortex lattice effect. The orientation
of the star coincides with the experimental data of the scanning tunneling
microscopy. That is, the ray of the star extends toward the nearest-neighbor
(next nearest-neighbor) vortex direction at higher (lower) energy.Comment: 10 pages, RevTex, 32 figure
Polarization fluctuations in vertical cavity surface emitting lasers: a key to the mechanism behind polarization stability
We investigate the effects of the electron-hole spin dynamics on the
polarization fluctuations in the light emitted from a vertical cavity surface
emitting laser (VCSEL). The Langevin equations are derived based on a rate
equation model including birefringence, dichroism, and two carrier density
pools seperately coupled to right and left circular polarization. The results
show that the carrier dynamics phase lock the polarization fluctuations to the
laser mode. This is clearly seen in the difference between fluctuations in
ellipticity and fluctuations in polarization direction. Seperate measurements
of the polarization fluctuations in ellipticity and in polarization direction
can therefore provide quantitative information on the non-linear contribution
of the carrier dynamics to polarization stability in VCSELs.Comment: 6 pages RevTex and 3 figures, to be published in Quantum and
Semiclassical Optics, minor changes to the discussion of timescale
Possible Experience: from Boole to Bell
Mainstream interpretations of quantum theory maintain that violations of the
Bell inequalities deny at least either realism or Einstein locality. Here we
investigate the premises of the Bell-type inequalities by returning to earlier
inequalities presented by Boole and the findings of Vorob'ev as related to
these inequalities. These findings together with a space-time generalization of
Boole's elements of logic lead us to a completely transparent Einstein local
counterexample from everyday life that violates certain variations of the Bell
inequalities. We show that the counterexample suggests an interpretation of the
Born rule as a pre-measure of probability that can be transformed into a
Kolmogorov probability measure by certain Einstein local space-time
characterizations of the involved random variables.Comment: Published in: EPL, 87 (2009) 6000
Large Scale Structure in CHILES
We demonstrate that the Discrete Persistent Source Extractor (DisPerSE) can
be used with spectroscopic redshifts to define the cosmic web and its distance
to galaxies in small area deepfields. Here we analyze the use of DisPerSE to
identify structure in observational data. We apply DisPerSE to the distribution
of galaxies in the COSMOS field and find the best parameters to identify
filaments. We compile a catalog of 11500 spectroscopic redshifts from the
Galaxy and Mass Assembly (GAMA) G10 data release. We analyze two-dimensional
slices, extract filaments and calculate the distance for each galaxy to its
nearest filament. We find that redder and more massive galaxies are closer to
filaments. To study the growth of galaxies across cosmic time, and environment,
we are carrying out an HI survey covering redshifts z = 0 - 0.45, the COSMOS HI
Large Extragalactic Survey (CHILES). In addition we present the predicted HI
mass fraction as a function of distance to filaments for the spectroscopically
known galaxies in CHILES. Lastly, we discuss the cold gas morphology of a few
individual galaxies and their positions with respect to the cosmic web. The
identification of the cosmic web, and the ability of CHILES to study the
resolved neutral hydrogen morphologies and kinematics of galaxies, will allow
future studies of the properties of neutral hydrogen in different cosmic web
environments across the redshift range z = 0.1 - 0.45.Comment: Accepted for publication in the Astronomical Journal; 11 pages ; 8
figure
Study of instabilities and transition to turbulence in a linear hall accelerator
Magnetospheric instabilities and transition to plasma turbulence in Hall current accelerator
Subwavelength localization and toroidal dipole moment of spoof surface plasmon polaritons
We experimentally and theoretically demonstrate subwavelength scale localization of spoof surface plasmon polaritons at a point defect in a two-dimensional groove metal array. An analytical expression for dispersion relation of spoof surface plasmon polaritons substantiates the existence of a band gap where a defect mode can be introduced. A waveguide coupling method allows us to excite localized spoof surface plasmon polariton modes and measure their resonance frequencies. Numerical calculations confirm that localized modes can have a very small modal volume and a high Q factor both of which are essential in enhancing light-matter interactions. Interestingly, we find that the localized spoof surface plasmon polariton has a significant toroidal dipole moment, which is responsible for the high Q factor, as well as an electric quadrupole moment. In addition, the dispersion properties of spoof surface plasmon polaritons are analyzed using a modal expansion method and numerical calculations
New weldable high strength aluminum alloys for cryogenic service
Weldable high strength aluminum alloys for cryogenic structure and tankage applications in liquid propellant space booster
- …