20,295 research outputs found
Protocols for characterizing quantum transport through nano-structures
In this work, we have analyzed the exact closed-form solutions for transport
quantities through a mesoscopic region which may be characterized by a
polynomial functional of resonant transmission functions. These are then
utilized to develop considerably improved protocols for parameters relevant for
quantum transport through molecular junctions and quantum dots. The protocols
are shown to be experimentally feasible and should yield the parameters at much
higher resolution than the previously proposed ones.Comment: 5 pages, 2 figure
Remark about Non-BPS D-Brane in Type IIA Theory
In this paper we would like to show simple mechanisms how from the action for
non-BPS D-brane we can obtain action describing BPS D(p-1)-brane in Type IIA
theory.Comment: 13 pages, completely rewritten pape
An Imaging Polarimeter(IMPOL) for multi-wavelength observations
Taking advantage of the advances in array detector technology, an imaging
polarimeter (IMPOL) has been constructed for measuring linear polarization in
the wavelength band from 400-800 nm. It makes use of a Wollaston prism as the
analyser to measure simultaneously the two orthogonal polarization components
that define a Stoke's parameter. An achromatic half-wave plate is used to
rotate the plane of polarization with respect to the axis of the analyser so
that the second Stoke's parameter also can be determined. With a field of view
correponding to about 30x30 sq. mm for a 1.2 m, f/13 telescope, a sensitive,
liquid-nitrogen cooled CCD camera as the detector and a built-in acquisition
and guidance unit, the instrument can be used for studying stellar fields or
extended objects with an angular resolution close to 2 arcsec. The instrumental
polarization is less than 0.05% and the accuracies of measurement are primarily
limited by photon noise for typical observations.Comment: 10 pages including 5 embedded figures; submitted to Astronomy and
Astrophysics Supplement Series; available on request to A. N. Ramaprakash
([email protected] or [email protected]); quote report n
The Schwinger SU(3) Construction - II: Relations between Heisenberg-Weyl and SU(3) Coherent States
The Schwinger oscillator operator representation of SU(3), studied in a
previous paper from the representation theory point of view, is analysed to
discuss the intimate relationships between standard oscillator coherent state
systems and systems of SU(3) coherent states. Both SU(3) standard coherent
states, based on choice of highest weight vector as fiducial vector, and
certain other specific systems of generalised coherent states, are found to be
relevant. A complete analysis is presented, covering all the oscillator
coherent states without exception, and amounting to SU(3) harmonic analysis of
these states.Comment: Latex, 51 page
Spectral changes in layered -electron systems induced by Kondo hole substitution in the boundary-layer
We investigate the effect of disorder on the dynamical spectrum of layered
-electron systems. With random dilution of -sites in a single Kondo
insulating layer, we explore the range and extent to which Kondo hole
incoherence can penetrate into adjacent layers. We consider three cases of
neighboring layers: band insulator, Kondo insulator and simple metal. The
disorder-induced spectral weight transfer, used here for quantification of the
proximity effect, decays algebraically with distance from the boundary layer.
Further, we show that the spectral weight transfer is highly dependent on the
frequency range considered as well as the presence of interactions in the clean
adjacent layers. The changes in the low frequency spectrum are very similar
when the adjacent layers are either metallic or Kondo insulating, and hence are
independent of interactions. In stark contrast, a distinct picture emerges for
the spectral weight transfers across large energy scales. The spectral weight
transfer over all energy scales is much higher when the adjacent layers are
non-interacting as compared to when they are strongly interacting Kondo
insulators. Thus, over all scales, interactions screen the disorder effects
significantly. We discuss the possibility of a crossover from non-Fermi liquid
to Fermi liquid behavior upon increasing the ratio of clean to disordered
layers in particle-hole asymmetric systems.Comment: 14 pages, 9 figure
Accelerated growth in outgoing links in evolving networks: deterministic vs. stochastic picture
In several real-world networks like the Internet, WWW etc., the number of
links grow in time in a non-linear fashion. We consider growing networks in
which the number of outgoing links is a non-linear function of time but new
links between older nodes are forbidden. The attachments are made using a
preferential attachment scheme. In the deterministic picture, the number of
outgoing links at any time is taken as where is
the number of nodes present at that time. The continuum theory predicts a power
law decay of the degree distribution: , while the degree of the node introduced at time is given by
when the
network is evolved till time . Numerical results show a growth in the degree
distribution for small values at any non-zero . In the stochastic
picture, is a random variable. As long as is time-dependent, e.g.,
when follows a distribution . The behaviour
of changes significantly as is varied: for , the
network has a scale-free distribution belonging to the BA class as predicted by
the mean field theory, for smaller values of it shows different
behaviour. Characteristic features of the clustering coefficients in both
models have also been discussed.Comment: Revised text, references added, to be published in PR
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