5,941 research outputs found
A study of atmosphere-ionosphere-magnetosphere coupling
The properties of low energy plasma in the magnetosphere were predicted. The effects of wave particle interactions involving the concept of plasmons are studied, and quantum mechanical formulations are used for the processes occurring and bulk energization of the low energy plasma are investigated through the concept of the energy momentum tensor for the plasma and its electromagnetic environment
Superspace formulation of general massive gauge theories and geometric interpretation of mass-dependent BRST symmetries
A superspace formulation is proposed for the osp(1,2)-covariant Lagrangian
quantization of general massive gauge theories. The superalgebra os0(1,2) is
considered as subalgebra of sl(1,2); the latter may be considered as the
algebra of generators of the conformal group in a superspace with two
anticommuting coordinates. The mass-dependent (anti)BRST symmetries of proper
solutions of the quantum master equations in the osp(1,2)-covariant formalism
are realized in that superspace as invariance under translations combined with
mass-dependent special conformal transformations. The Sp(2) symmetry - in
particular the ghost number conservation - and the "new ghost number"
conservation are realized as invariance under symplectic rotations and
dilatations, respectively. The transformations of the gauge fields - and of the
full set of necessarily required (anti)ghost and auxiliary fields - under the
superalgebra sl(1,2) are determined both for irreducible and first-stage
reducible theories with closed gauge algebra.Comment: 35 pages, AMSTEX, precision of reference
Unified Chew-Mandelstam SAID analysis of pion photoproduction data
A unified description of single-pion photoproduction data, together with
pion- and eta-hadroproduction data, has been achieved in a Chew-Mandelstam
parametrization which is consistent with unitarity at the two-body level.
Energy-dependent and single-energy partial wave analyses of pion
photoproduction data have been performed and compared to previous SAID fits and
multipoles from the Mainz and Bonn-Gatchina groups.Comment: 11 pages, 9 figures, and 2 table
Versatile Cold Atom Source for Multi-Species Experiments
We present a dual-species oven and Zeeman slower setup capable of producing
slow, high-flux atomic beams for loading magneto-optical traps. Our compact and
versatile system is based on electronic switching between different magnetic
field profiles and is applicable to a wide range of multi-species experiments.
We give details of the vacuum setup, coils and simple electronic circuitry. In
addition, we demonstrate the performance of our system by optimized, sequential
loading of magneto-optical traps of lithium-6 and cesium-133.Comment: 7 pages, 10 figure
Unsupervised classification and areal measurement of land and water coastal features on the Texas coast
Multispectral scanner (MSS) digital data from ERTS-1 was used to delineate coastal land, vegetative, and water features in two portions of the Texas Coastal Zone. Data (Scene ID's 1037-16244 and 1037-16251) acquired on August 29, 1972, were analyzed on NASA Johnson Space Center systems through the use of two clustering algorithms. Seventeen to 30 spectrally homogeneous classes were so defined. Many classes were identified as being pure features such as water masses, salt marsh, beaches, pine, hardwoods, and exposed soil or construction materials. Most classes were identified to be mixtures of the pure class types. Using an objective technique for measuring the percentage of wetland along salt marsh boundaries, an analysis was made of the accuracy of areal measurement of salt marshes. Accuracies ranged from 89 to 99 percent. Aircraft photography was used as the basis for determining the true areal size of salt marshes in the study sites
Toward a unified description of hadro- and photoproduction amplitudes
The near-term objectives of the research program at the Data Analysis Center
are established within the context of the existing partial wave analyses
available through the online suite of analysis and database codes accessible
through SAID, the Scattering Analysis Interactive Database. This presentation
reviews the efforts to determine a model independent method to obtain sets of
partial wave amplitudes for strong and electromagnetic reactions, the
interpretation of the amplitudes in terms of the excited states of the nucleon,
the role of new precision unpolarized and polarized data, and new developments
aimed at determining the photoproduction mulitpoles in a unitary,
coupled-channel approach. The Chew-Mandelstam technique is discussed and
applied to the problem of the S-wave pion- and eta-photoproduction amplitudes.
The resulting eta production amplitudes exhibit the expected resonant behavior
near the eta production threshold. Application of this method to a unified
description of the hadro- and photoproduction amplitudes is discussed.Comment: 4 pages, 1 figure, invited talk for the 12th International Conference
on Meson-Nucleon Physics and the Structure of the Nucleon (MENU 2010),
Williamsburg, Virginia, 31 May - 4 Jun 201
Effect of Sigma-beam Asymmetry Data on Fits to Single Pion Photoproduction off Neutron
We investigate the influence of new GRAAL Sigma-beam asymmetry measurements
on the neutron in multipole fits to the single-pion photoproduction database.
Results are compared to those found with the addition of a double-polarization
quantity associated with the sum rule.Comment: 4 pages, 4 figures, 1 table; v2/v3: minor corrections; Presented at
the 8th Workshop on the Physics of Excited Nucleons (NSTAR2011), Newport
News, USA, May 201
High efficiency tomographic reconstruction of quantum states by quantum nondemolition measurements
We propose a high efficiency tomographic scheme to reconstruct an unknown
quantum state of the qubits by using a series of quantum nondemolition (QND)
measurements. The proposed QND measurements of the qubits are implemented by
probing the the stationary transmissions of the dispersively-coupled resonator.
It is shown that only one kind of QND measurements is sufficient to determine
all the diagonal elements of the density matrix of the detected quantum state.
The remaining non-diagonal elements of the density matrix can be determined by
other spectral measurements by beforehand transferring them to the diagonal
locations using a series of unitary operations. Compared with the pervious
tomographic reconstructions based on the usual destructively projective (DP)
measurements (wherein one kind of such measurements could only determine one
diagonal element of the density matrix), the present approach exhibits
significantly high efficiency for N-qubit (N > 1). Specifically, our generic
proposal is demonstrated by the experimental circuit-quantumelectrodynamics
(circuit-QED) systems with a few Josephson charge qubits.Comment: 9pages,4figure
Ramsey numbers and adiabatic quantum computing
The graph-theoretic Ramsey numbers are notoriously difficult to calculate. In
fact, for the two-color Ramsey numbers with , only nine are
currently known. We present a quantum algorithm for the computation of the
Ramsey numbers . We show how the computation of can be mapped
to a combinatorial optimization problem whose solution can be found using
adiabatic quantum evolution. We numerically simulate this adiabatic quantum
algorithm and show that it correctly determines the Ramsey numbers R(3,3) and
R(2,s) for . We then discuss the algorithm's experimental
implementation, and close by showing that Ramsey number computation belongs to
the quantum complexity class QMA.Comment: 4 pages, 1 table, no figures, published versio
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