Quantum Potential and Symmetries in Extended Phase Space

The behavior of the quantum potential is studied for a particle in a linear and a harmonic potential by means of an extended phase space technique. This is done by obtaining an expression for the quantum potential in momentum space representation followed by the generalization of this concept to extended phase space. It is shown that there exists an extended canonical transformation that removes the expression for the quantum potential in the dynamical equation. The situation, mathematically, is similar to disappearance of the centrifugal potential in going from the spherical to the Cartesian coordinates that changes the physical potential to an effective one. The representation where the quantum potential disappears and the modified Hamilton-Jacobi equation reduces to the familiar classical form, is one in which the dynamical equation turns out to be the Wigner equation.Comment: Published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA

Operator Gauge Symmetry in QED

In this paper, operator gauge transformation, first introduced by Kobe, is applied to Maxwell's equations and continuity equation in QED. The gauge invariance is satisfied after quantization of electromagnetic fields. Inherent nonlinearity in Maxwell's equations is obtained as a direct result due to the nonlinearity of the operator gauge transformations. The operator gauge invariant Maxwell's equations and corresponding charge conservation are obtained by defining the generalized derivatives of the first and second kinds. Conservation laws for the real and virtual charges are obtained too. The additional terms in the field strength tensor are interpreted as electric and magnetic polarization of the vacuum.Comment: Published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA

Measurement of the atmospheric primary aberrations by a 4-aperture differential image motion monitor

The present paper investigates and discusses the ability of the Hartmann test with a 4-aperture differential image motion monitor (DIMM) to measure the atmospheric primary aberrations which, in turn, can be used for the calculation of the atmospheric coherence time. Through performing numerical simulations, we show that the 4-aperture DIMM is able to measure the defocus and astigmatism terms correctly whereas its results are not reliable for the coma. The most important limitations in the measurement of the primary aberrations by the 4-aperture DIMM are the centroid displacements of the spots which are caused by the higher order aberrations. This effect is negligible in the calculation of the defocus and astigmatisms, whereas it cannot be ignored in the calculation of the coma

Application of irradiance transport equation in aspheric surface testing

A method for aspheric surface testing (AST) is presented in this paper. The method fundamentally draws on solving the irradiance transport equation (ITE). It is shown by simulation that the accuracy of ITE solution depends on proper selection of defocus distance and also demonstrate that the best defocus distance depends on peak to valley and spatial extend of phase distribution. (C) 2011 Elsevier GmbH. All rights reserved

Investigating the semi-regular light variations of the bright M5 supergiant: alpha Herculis

status: publishe