39,497 research outputs found
Dispersion and transitions of dipolar plasmon modes in graded plasmonic waveguides
Coupled plasmon modes are studied in graded plasmonic waveguides, which are
periodic chains of metallic nanoparticles embedded in a host with gradually
varying refractive indices. We identify three types of localized modes called
"light", "heavy", and "light-heavy" plasmonic gradons outside the passband,
according to various degrees of localization. We also demonstrate new
transitions among extended and localized modes when the interparticle
separation is smaller than a critical , whereas the three types of
localized modes occur for , with no extended modes. The transitions can
be explained with phase diagrams constructed for the lossless metallic systems.Comment: Preliminary results have been presented at ETOPIM 7. Submitted to
Appl. Phys. Let
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Mechanical Properties and Biological Responses of Bioactive Glass Ceramics Processed using Indirect SLS
This paper will report on research which aims to generate bone replacement components by
processing bioactive glass-ceramic powders using indirect selective laser sintering. The indirect
SLS route has been chosen as it offers the ability to tailor the shape of the implant to the
implantation site, and two bioactive glass ceramic materials have been processed through this
route: apatite-mullite and apatite-wollostanite. The results of bend tests, to investigate
mechanical properties, and in vitro and in vivo experiments to investigate biological responses of
the materials will be reported, and the suitability of completed components for implant will be
assessed.Mechanical Engineerin
Magnetoconductance of the quantum spin Hall state
We study numerically the edge magnetoconductance of a quantum spin Hall
insulator in the presence of quenched nonmagnetic disorder. For a finite
magnetic field B and disorder strength W on the order of the bulk gap E_g, the
conductance deviates from its quantized value in a manner which appears to be
linear in |B| at small B. The observed behavior is in qualitative agreement
with the cusp-like features observed in recent magnetotransport measurements on
HgTe quantum wells. We propose a dimensional crossover scenario as a function
of W, in which for weak disorder W < E_g the edge liquid is analogous to a
disordered spinless 1D quantum wire, while for strong disorder W > E_g, the
disorder causes frequent virtual transitions to the 2D bulk, where the
originally 1D edge electrons can undergo 2D diffusive motion and 2D
antilocalization.Comment: 5 pages, 3 figure
Fermion Resonances on a Thick Brane with a Piecewise Warp Factor
In this paper, we mainly investigate the problems of resonances of massive KK
fermions on a single scalar constructed thick brane with a piecewise warp
factor matching smoothly. The distance between two boundaries and the other
parameters are determined by one free parameter through three junction
conditions. For the generalized Yukawa coupling
with odd , the mass eigenvalue , width , lifetime
, and maximal probability of fermion resonances are obtained.
Our numerical calculations show that the brane without internal structure also
favors the appearance of resonant states for both left- and right-handed
fermions. The scalar-fermion coupling and the thickness of the brane influence
the resonant behaviors of the massive KK fermions.Comment: V3: 15 pages, 7 figures, published versio
An Exact Algorithm for TSP in Degree-3 Graphs via Circuit Procedure and Amortization on Connectivity Structure
The paper presents an O^*(1.2312^n)-time and polynomial-space algorithm for
the traveling salesman problem in an n-vertex graph with maximum degree 3. This
improves the previous time bounds of O^*(1.251^n) by Iwama and Nakashima and
O^*(1.260^n) by Eppstein. Our algorithm is a simple branch-and-search
algorithm. The only branch rule is designed on a cut-circuit structure of a
graph induced by unprocessed edges. To improve a time bound by a simple
analysis on measure and conquer, we introduce an amortization scheme over the
cut-circuit structure by defining the measure of an instance to be the sum of
not only weights of vertices but also weights of connected components of the
induced graph.Comment: 24 pages and 4 figure
Constraint on the CKM angle alpha from the experimental measurements of CP violation in B_d^0 --> pi^+ pi^- decay
In this paper, we study and try to find the constraint on the CKM angle alpha
from the experimental measurements of CP violation in B_d^0 --> pi^+ pi^-
decay, as reported very recently by BaBar and Belle Collaborations. After
considering uncertainties of the data and the ratio r of penguin over tree
amplitude, we found that strong constraint on both the CKM angle alpha and the
strong phase delta can be obtained from the measured CP asymmetries S_{pi pi}
and A_{pi pi}: (a) the ranges of 87 degrees <= alpha <= 131 degrees and 36
degrees <= delta <= 144 degrees are allowed by 1 sigma of the averaged data for
r = 0.31; (b) for Belle's result alone, the limits on alpha and delta are 104
degrees <= alpha <= 139 degrees and 42 degrees <= delta <= 138 degrees for 0.32
<= r <= 0.41; and (c) the angle alpha larger than 90 degrees is preferred.Comment: Revtex, 17 pages with 6 ps/eps figure files, new Babar data Reported
at ICHEP 2002 considere
Error tolerance in an NMR Implementation of Grover's Fixed-Point Quantum Search Algorithm
We describe an implementation of Grover's fixed-point quantum search
algorithm on a nuclear magnetic resonance (NMR) quantum computer, searching for
either one or two matching items in an unsorted database of four items. In this
new algorithm the target state (an equally weighted superposition of the
matching states) is a fixed point of the recursive search operator, and so the
algorithm always moves towards the desired state. The effects of systematic
errors in the implementation are briefly explored.Comment: 5 Pages RevTex4 including three figures. Changes made at request of
referees; now in press at Phys Rev
Binding of Holes to Magnetic Impurities in a Strongly Correlated System
The effect of a magnetic (S=1/2) impurity coupled to a 2D system of
correlated electrons (described by the t--J model) is studied by exact
diagonalisations. It is found that, if the exchange coupling of the impurity
with the neighboring spins is ferromagnetic or weakly antiferromagnetic, an
extra hole can form bound states of different spatial symmetries with the
impurity extending to a few lattice spacings. The binding energy is maximum
when the impurity is completely decoupled (vacancy) and vanishes for an
antiferromagnetic coupling exceeding . Several peaks appear in the
single hole spectral function below the lower edge of the quasiparticle band as
signatures of the d-, s- and p-wave boundstates.Comment: Latex 11 pages, postscript files in uuencoded form, report#
LPQTH-94/
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