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Converting three-space matrices to equivalent six-space matrices for Delone scalars in S6.
The transformations from the primitive cells of the centered Bravais lattices to the corresponding centered cells have conventionally been listed as three-by-three matrices that transform three-space lattice vectors. Using those three-by-three matrices when working in the six-dimensional space of lattices represented as Selling scalars as used in Delone (Delaunay) reduction, one could transform to the three-space representation, apply the three-by-three matrices and then back-transform to the six-space representation, but it is much simpler to have the equivalent six-by-six matrices and apply them directly. The general form of the transformation from the three-space matrix to the corresponding matrix operating on Selling scalars (expressed in space S6) is derived, and the particular S6matrices for the centered Delone types are listed. (Note: in his later publications, Boris Delaunay used the Russian version of his surname, Delone.)
Gallium Arsenide preparation and QE Lifetime Studies using the ALICE Photocathode Preparation Facility
In recent years, Gallium Arsenide (GaAs) type photocathodes have become
widely used as electron sources in modern Energy Recovery Linac based light
sources such as the Accelerators and Lasers in Combined Experiments (ALICE) at
Daresbury Laboratory and as polarised electron source for the proposed
International Linear Collider (ILC). Once activated to a Low Electron Affinity
(LEA) state and illuminated by a laser, these materials can be used as a
high-brightness source of both polarised and un-polarised electrons. This paper
presents an effective multi-stage preparation procedure including heat
cleaning, atomic hydrogen cleaning and the activation process for a GaAs
photocathode. The stability of quantum efficiency (QE) and lifetime of
activated to LEA state GaAs photocathode have been studied in the ALICE
load-lock photocathode preparation facility which has a base pressure in the
order of 10^-11 mbar. These studies are supported by further experimental
evidence from surface science techniques such as X-ray Photoelectron
Spectroscopy (XPS) to demonstrate the processes at the atomic level.Comment: Presented at First International Particle Accelerator Conference,
IPAC'10, Kyoto, Japan, from 23 to 28 May 201
Dynamic instabilities of fracture under biaxial strain using a phase field model
We present a phase field model of the propagation of fracture under plane
strain. This model, based on simple physical considerations, is able to
accurately reproduce the different behavior of cracks (the principle of local
symmetry, the Griffith and Irwin criteria, and mode-I branching). In addition,
we test our model against recent experimental findings showing the presence of
oscillating cracks under bi-axial load. Our model again reproduces well
observed supercritical Hopf bifurcation, and is therefore the first simulation
which does so
Canonical Formulation of pp-waves
We construct a Hamiltonian formulation for the class of plane-fronted
gravitational waves with parallel rays (pp-waves). Because of the existence of
a light-like Killing vector, the dynamics is effectively reduced to a 2+1
evolution with "time" chosen to be light-like. In spite of the vanishing action
this allows us to geometrically identify a symplectic form as well as dynamical
Hamiltonian, thus casting the system into canonical form.Comment: To appear in the "Obregon Festschrift
Polariton Lasing in a Multilevel Quantum Dot Strongly Coupled To a Single Photon Mode
We present an approximate analytic expression for the photoluminescence
spectral function of a model polariton system, which describes a quantum dot,
with a finite number of fermionic levels, strongly interacting with the lowest
photon mode of a pillar microcavity. Energy eigenvalues and wavefunctions of
the electron-hole-photon system are obtained by numerically diagonalizing the
Hamiltonian. Pumping and photon losses through the cavity mirrors are described
with a master equation, which is solved in order to determine the stationary
density matrix. The photon first-order correlation function, from which the
spectral function is found, is computed with the help of the Quantum Regression
Theorem. The spectral function qualitatively describes the polariton lasing
regime in the model, corresponding to pumping rates two orders of magnitude
lower than those needed for ordinary (photon) lasing. The second-order
coherence functions for the photon and the electron-hole subsystems are
computed as functions of the pumping rate.Comment: version accepted in Phys. Rev.
Use of ERTS-1 data in identification, classification, and mapping of salt-affected soils in California
There are no author-identified significant results in this report
Lambda's, V's and optimal cloning with stimulated emission
We show that optimal universal cloning of the polarization state of photons
can be achieved via stimulated emission in three-level systems, both of the
Lambda and the V type. We establish the equivalence of our systems with coupled
harmonic oscillators, which permits us to analyze the structure of the cloning
transformations realized. These transformations are shown to be equivalent to
the optimal cloning transformations for qubits discovered by Buzek and Hillery,
and Gisin and Massar. The down-conversion cloner discovered previously by some
of the authors is obtained as a limiting case. We demonstrate an interesting
equivalence between systems of Lambda atoms and systems of pairwise entangled V
atoms. Finally we discuss the physical differences between our photon cloners
and the qubit cloners considered previously and prove that the bounds on the
fidelity of the clones derived for qubits also apply in our situation.Comment: 10 page
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