The spectral and polarization characteristics of the nonspherically decaying radiation generated by polarization currents with superluminally rotating distribution patterns

We present a theoretical study of the emission from a superluminal polarization current whose distribution pattern rotates (with an angular frequency $\omega$) and oscillates (with a frequency $\Omega$) at the same time, and which comprises both poloidal and toroidal components. This type of polarization current is found in recent practical machines designed to investigate superluminal emission. We find that the superluminal motion of the distribution pattern of the emitting current generates localized electromagnetic waves that do not decay spherically, i.e. that do not have an intensity diminishing like ${R_P}^{-2}$ with the distance $R_P$ from their source. The nonspherical decay of the focused wave packets that are emitted by the polarization currents does not contravene conservation of energy: the constructive interference of the constituent waves of such propagating caustics takes place within different solid angles on spheres of different radii ($R_P$) centred on the source. For a polarization current whose longitudinal distribution (over an azimuthal interval of length $2\pi$) consists of $m$ cycles of a sinusoidal wave train, the nonspherically decaying part of the emitted radiation contains the frequencies $\Omega \pm m\omega$; i.e. it contains {\it only} the frequencies involved in the creation and implementation of the source. This is in contrast to recent studies of the spherically decaying emission, which was shown to contain much higher frequencies. The polarization of the emitted radiation is found to be linear for most configurations of the source.Comment: 19 pages, six figure

The frequency spectrum of focused broadband pulses of electromagnetic radiation generated by polarization currents with superluminally rotating distribution patterns

We investigate the spectral features of the emission from a superluminal polarization current whose distribution pattern rotates with an angular frequency $\omega$ and oscillates with an incommensurate frequency $\Omega >\omega$. This type of polarization current is found in recent practical machines designed to investigate superluminal emission. Although all of the processes involved are linear, we find that the broadband emission contains frequencies that are higher than $\Omega$ by a factor of the order of $(\Omega/\omega)^2$. This generation of frequencies {\it not} required for the creation of the source stems from mathematically rigorous consequences of the familiar classical expression for the retarded potential. The results suggest practical applications for superluminal polarization currents as broad-band radiofrequency and infrared sources

Inadequacies in the conventional treatment of the radiation field of moving sources

There is a fundamental difference between the classical expression for the retarded electromagnetic potential and the corresponding retarded solution of the wave equation that governs the electromagnetic field. While the boundary contribution to the retarded solution for the {\em potential} can always be rendered equal to zero by means of a gauge transformation that preserves the Lorenz condition, the boundary contribution to the retarded solution of the wave equation governing the {\em field} may be neglected only if it diminishes with distance faster than the contribution of the source density in the far zone. In the case of a source whose distribution pattern both rotates and travels faster than light {\em in vacuo}, as realized in recent experiments, the boundary term in the retarded solution governing the field is by a factor of the order of $R^{1/2}$ {\em larger} than the source term of this solution in the limit that the distance $R$ of the boundary from the source tends to infinity. This result is consistent with the prediction of the retarded potential that part of the radiation field generated by a rotating superluminal source decays as $R^{-1/2}$, instead of $R^{-1}$, a prediction that is confirmed experimentally. More importantly, it pinpoints the reason why an argument based on a solution of the wave equation governing the field in which the boundary term is neglected (such as appears in the published literature) misses the nonspherical decay of the field

Direct optical excitation of a fullerene-incarcerated metal ion

The endohedral fullerene Er3N@C80 shows characteristic 1.5 micron photoluminescence at cryogenic temperatures associated with radiative relaxation from the crystal-field split Er3+ 4I13/2 manifold to the 4I15/2 manifold. Previous observations of this luminescence were carried out by photoexcitation of the fullerene cage states leading to relaxation via the ionic states. We present direct non-cage-mediated optical interaction with the erbium ion. We have used this interaction to complete a photoluminescence-excitation map of the Er3+ 4I13/2 manifold. This ability to interact directly with the states of an incarcerated ion suggests the possibility of coherently manipulating fullerene qubit states with light

Experimental observation of nonspherlcally-decaying radiation from a rotating superluminal source

We describe the experimental implementation of a superluminal (i.e., faster than light in vacuo) polarization current distribution that both oscillates and undergoes centripetal acceleration. Theoretical treatments predict that the radiation emitted by each volume element of the superluminally moving distribution pattern will comprise a Čerenkov-like envelope with two sheets that meet along a cusp. Correspondingly, the emission from the experimental machine is found to be tightly beamed in both the azimuthal and polar directions. The beaming is frequency independent and has a sharply defined and unchanging geometry determined only by the speed and path of the moving distribution pattern, i.e., by the parameters governing the structure of the Čerenkov-like envelopes. In addition, over a restricted range of angles, we detect the presence of cusps in the emitted radiation. These, which are due to the focusing of wave fronts on a propagating space curve, result in the reception, during a short time period, of radiation emitted over a considerably longer period of (retarded) source time. The intensity of the radiation at these angles was observed to decline more slowly with increasing distance from the source than would the emission from a conventional antenna. The angular distribution of the emitted radiation and the properties associated with the cusps are in good quantitative agreement with theoretical models of superluminal sources once the effect of reflections from the earth’s surface are taken into account. In particular, the prediction that the beaming and the slow decay should extend into the far zone has been tested to several hundred Fresnel distances (Rayleigh ranges). The excellent agreement between the theoretical calculations and the data suggests that the apparatus achieves precise and reproducible control of the polarization current and that similar machines could be of general interest for studying and utilizing the novel effects associated with superluminal electrodynamics.Publisher’s Note: The original article was published without numerous corrections submitted by the authors. The corrected version is appended to this record. The URL for the corrected version is: http://link.aip.org/link/doi/10.1063/1.183339

Gender discourse, awareness, and alternative responses for men in everyday living

In this paper, the authors use examples from their experiences to explore the nuances and complexities of contemporary gender practices. They draw on discourse and positioning theories to identify the ways in which culturally dominant, and difficult to notice, gender constructions help shape everyday experiences. In addition, the authors share their view that there are benefits in developing skills in noticing contemporary practices made available by dominant gender constructions. Such noticing expands possibilities for ways of responding and relating that might produce outcomes for men and women that fit with their hopes for living