Artin monoids inject in their groups

We prove that the natural homomorphism from an Artin monoid to its associated Artin group is always injectiveComment: 20 pages, 3 figures, see http://math.u-bourgogne.fr/topolog/pari

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

Optimal cloning of coherent states by linear optics

We describe an optical scheme for optimal Gaussian n to m cloning of coherent states. The scheme, which generalizes a recently demonstrated scheme for 1 to 2 cloning, involves only linear optical components and homodyne detection.Comment: 5 pages, 4 figures, presented at the 13th Central European Workshop on Quantum Optics, May 23-27 2006, Vienna, Austria (Proceedings will be published in "Acta Physica Hungarica"); reference added, Eq. (8) correcte

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

Programmable purification of type-I polarization-entanglement

We suggest and demonstrate a scheme to compensate spatial and spectral decoherence effects in the generation of polarization entangled states by type-I parametric downconversion. In our device a programmable spatial light modulator imposes a polarization dependent phase-shift on different spatial sections of the overall downconversion output and this effect is exploited to realize an effective purification technique for polarization entanglement.Comment: published versio

Description strategies for naive and expert users

It is widely recognized that a question-answering system should be able to tailor its answers to the user. One of the dimensions along which this tailoring can occur is with respect to the level of knowledge of a user about a domain. In particular, responses should be different depending on whether they are addressed to naive or expert users. To understand what those differences should be, we analyzed texts from adult and junior encyclopedias. We found that two different strategies were used in describing complex physical objects to juniors and adults. We show how these strategies have been implemented on a test database