3,625 research outputs found
Asymptotic formulas for generalized elliptic-type integrals
AbstractEpstein-Hubbell [1] elliptic-type integrals occur in radiation field problems. The object of the present paper is to consider a unified form of different elliptic-type integrals, defined and developed recently by several authors. We obtain asymptotic formulas for the generalized elliptic-type integrals
Asymmetric quantum channel for quantum teleportation
There are a few obstacles, which bring about imperfect quantum teleportation
of a continuous variable state, such as unavailability of maximally entangled
two-mode squeezed states, inefficient detection and imperfect unitary
transformation at the receiving station. We show that all those obstacles can
be understood by a combination of an {\it asymmetrically-decohered} quantum
channel and perfect apparatuses for other operations. For the
asymmetrically-decohered quantum channel, we find some counter-intuitive
results; one is that teleportation does not necessarily get better as the
channel is initially squeezed more and another is when one branch of the
quantum channel is unavoidably subject to some imperfect operations, blindly
making the other branch as clean as possible may not result in the best
teleportation result. We find the optimum strategy to teleport an unknown field
for a given environment or for a given initial squeezing of the channel.Comment: 4pages, 1figur
Tachyon Kinks in Boundary String Field Theory
We study tachyon kinks with and without electromagnetic fields in the context
of boundary string field theory. For the case of pure tachyon only an array of
kink-antikink is obtained. In the presence of electromagnetic coupling, all
possible static codimension-one soliton solutions such as array of
kink-antikink, single topological BPS kink, bounce, half kink, as well as
nonBPS topological kink are found, and their properties including the
interpretation as branes are analyzed in detail. Spectrum of the obtained kinks
coincides with that of Dirac-Born-Infeld type effective theory.Comment: LaTex, 29 pages, 17 Figure
Role of many-body entanglement in decoherence processes
A pure state decoheres into a mixed state as it entangles with an
environment. When an entangled two-mode system is embedded in a thermal
environment, however, each mode may not be entangled with its environment by
their simple linear interaction. We consider an exactly solvable model to study
the dynamics of a total system, which is composed of an entangled two-mode
system and a thermal environment, and also an array of infinite beam splitters.
It is shown that many-body entanglement of the system and the environment plays
a crucial role in the process of disentangling the system.Comment: 4 pages, 1 figur
A Detailed Monte-Carlo Simulation for the Belle TOF System
We have developed a detailed Monte Carlo simulation program for the Belle TOF
system. Based on GEANT simulation, it takes account of all physics processes in
the TOF scintillation counters and readout electronics. The simulation
reproduces very well the performance of the Belle TOF system, including the
dE/dx response, the time walk effect, the time resolution, and the hit
efficiency due to beam background. In this report, we will describe the Belle
TOF simulation program in detail.Comment: To be submitted to NI
Optimal conclusive teleportation of a d-dimensional unknown state
We formulate a conclusive teleportation protocol for a system in
d-dimensional Hilbert space utilizing the positive operator valued measurement
at the sending station. The conclusive teleportation protocol ensures some
perfect teleportation events when the channel is only partially entangled, at
the expense of lowering the overall average fidelity. We find the change of the
fidelity as optimizing the conclusive teleportation events and discuss how much
information remains in the inconclusive parts of the teleportation.Comment: 7 pages, 1 figure; figure correcte
Reliability of the beamsplitter based Bell-state measurement
A linear 50/50 beamsplitter, together with a coincidence measurement, has
been widely used in quantum optical experiments, such as teleportation, dense
coding, etc., for interferometrically distinguishing, measuring, or projecting
onto one of the four two-photon polarization Bell-states . In
this paper, we demonstrate that the coincidence measurement at the output of a
beamsplitter cannot be used as an absolute identifier of the input state
nor as an indication that the input photons have projected to
the state.Comment: 4 pages, two-colum
Reversible magnetization of MgB2 single crystals with a two-gap nature
We present reversible magnetization measurements on MgB2 single crystals in
magnetic fields up to 2.5 T applied parallel to the crystal's c-axis. This
magnetization is analyzed in terms of the Hao-Clem model, and various
superconducting parameters, such as the critical fields [Hc(0) and Hc2(0)], the
characteristic lengths [xi(0) and lambda(0)], and the Ginzburg-Landau
parameter, kappa, are derived. The temperature dependence of the magnetic
penetration depth, lambda(T), obtained from the Hao-Clem analysis could not be
explained by theories assuming a single gap. Our data are well described by
using a two-gap model.Comment: 20 pages, 1 table, 4 figures, will be published in Phys. Rev.
Effects of Boron Purity, Mg Stoichiometry and Carbon Substitution on Properties of Polycrystalline MgB
By synthesizing MgB using boron of different nominal purity we found
values of the residual resistivity ratio () from 4 to
20, which covers almost all values found in literature. To obtain high values
of , high purity reagents are necessary. With the isotopically pure boron
we obtained the highest 20 for the stoichiometric compound. We also
investigated MgB samples with 0.8 1.2. For the range
MgB up to MgB we found average values
of between 14 and 24. For smaller variations in stoichiometry () . All of our data point to the conclusion that high
() and low () are intrinsic
material properties associated with high purity MgB. In addition we have
performed initial work on optimizing the formation of carbon doped MgB
via the use of BC. Nearly single phase material can be formed by reaction
of nominal Mg(BC) for 24 hours at . The
for this composition is between and (depending on
criterion).Comment: accepted to Physica C, special MgB2 issu
A SOA-Based Platform-Specific Framework for Context-Aware Mobile Applications
Context-aware mobile applications are intelligent applications that can monitor the user’s context and, in case of changes in this context, consequently adapt their behaviour in order to satisfy the user’s current needs or anticipate the user’s intentions. The design of such applications relies on dynamic middleware platforms that consist of a variety of components. These components are distributed in the environment and interoperate by making use of each other’s services. In the A-MUSE project, we defined a design methodology based on MDA principles that relies on a SOA reference architecture for context-aware mobile applications. This paper shows how abstract concepts in the design of such applications can be applied to realize concrete components that guarantee architectural interoperability. We also present a platform-specific framework that uses BPEL, UDDI registry and web services as target technologies to implement our reference architecture
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