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Usual Gaussian beams are particular scalar solutions to the paraxial Helmholtz equation, which neglect the vector nature of light. In order to overcome this inconvenience, Simon et al. (J. Opt. Soc. Am. A 1986, 3, 536–540) found a paraxial solution to Maxwell’s equation in vacuum, which includes polarization in a natural way, though still preserving the spatial Gaussianity of the beams. In this regard, it seems that these solutions, known as Gauss-Maxwell beams, are particularly appropriate and a natural tool in optical problems dealing with Gaussian beams acted or manipulated by polarizers. In this work, inspired in the Bohmian picture of quantum mechanics, a hydrodynamic-type extension of such a formulation is provided and discussed, complementing the notion of electromagnetic field with that of (electromagnetic) flow or streamline. In this regard, the method proposed has the advantage that the rays obtained from it render a bona fide description of the spatial distribution of electromagnetic energy, since they are in compliance with the local space changes undergone by the time-averaged Poynting vector. This feature confers the approach a potential interest in the analysis and description of single-photon experiments, because of the direct connection between these rays and the average flow exhibited by swarms of identical photons (regardless of the particular motion, if any, that these entities might have), at least in the case of Gaussian input beams. In order to illustrate the approach, here it is applied to two common scenarios, namely the diffraction undergone by a single Gauss-Maxwell beam and the interference produced by a coherent superposition of two of such beams., Ministerio de Ciencia e Innovación (MICINN)/FEDER, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

Recently, Panuski and Mungan presented the results of their study of light diffraction from a variable-width single slit by observing and measuring the diffraction pattern on an observation screen placed at a fixed distance. In this way, the authors were able to demonstrate to students the important near-field effects for single-slit diffraction, which most often have been neglected in introductory courses. In this paper, we show that there exists very good agreement between observed data and theoretical calculations by plotting intensity from single slits using a method with Fresnel-Kirchhoff integrals (Fig. 1). In addition to these comparisons, and with the evaluation of the Fresnel numbers, we argue that Panuski and Mungan demonstrated not only the near-field Fresnel, but also the far-field Fraunhofer regimes as well as the transition between the two. Furthermore, with a greater increase in the slit width, the transition to the geometric regime can be demonstrated (Fig. 2).

In Serbia, one of the former republics of Socialist Federal Republic of Yugoslavia, men and women have equal access to higher education and professional employment. However, in practice, this equality is not always realized. In this paper we describe the status of women in physics in Serbia, focusing on student gender ratios and on positions held. The financial contributions of the Serbian government to the scientific sector are not sufficient. Many young physicists enter the information technology sector, where they can earn higher salaries. In addition, the lack of career opportunities motivates scientists to go abroad, so each year, more and more young people leave Serbia. Today, many young Serbian physicists plan their departure during their studies and leave the country immediately after graduation. We present statis- tical data for the last several years, reviewing the percentage of women who are pursuing physics as a subject of study or a profession. We report gender ratios at various career stages. Teaching at the primary and high-school level is the main professional activity for female physicists in Serbia. Even though a large percentage (about 50%) of Serbian physicists are female, few women hold positions in which decisions about scientific and educational policy are made. When women achieve leadership positions, their educational attainments often outstrip those required for the positions. Only six women have a high-level management position.

In the diffraction pattern produced by a half-plane sharp edge when it obstructs the passage of a laser beam, two characteristic regions are noticeable. There is a central region, where the diffraction of laser light appears in the region of geometric shadow, while intensity oscillations are observed in the non-obstructed area. On both sides of the edge, there are also very long light traces along the normal to the edge of the obstacle. The theoretical explanation of this phenomenon is based on the Fresnel–Kirchhoff diffraction theory applied to the Gaussian beam propagation behind the obstacle. In this paper, we supplement this explanation by considering electromagnetic flow lines, which provide a more complete interpretation of the phenomenon in terms of electric and magnetic fields and flux lines; at the same time, that can be related to average photon paths.

Atomic three-grating Mach Zehnder interferometry constitutes an important tool to probe fundamental aspects the quantum theory. There is, however, a remarkable gap in the literature betweenthe oversimplified models and robust numerical simulations considered to describe the corresponding experiments. Consequently, the former usually lead to paradoxical scenarios, such as the wave-particle dual behavior of atoms, while the latter make difficult the data analysis in simple terms. Here these issues are tackled by means of a simple grating working model consisting of evenly-spaced Gaussian slits. As is shown, this model suffices to explore and explain such experiments both analytically and numerically, giving a good account of the full atomic journey inside the interferometer, and hence contributing to make less mystic the physics involved. More specifically, it provides a clear and unambiguous picture of the wavefront splitting that takes place inside the interferometer, illustrating how the momentum along each emerging diffraction order is well defined even though the wave function itself still displays a rather complex shape. To this end, the local transverse momentum is also introduced in this context as a reliable analytical tool. The splitting, apart from being a key issue to understand atomic Mach-Zehnder interferometry, also demonstrates at a fundamental level how wave and particle aspects are always present in the experiment, without incurring in any contradiction or interpretive paradox. On the other hand, at a practical level, the generality and versatility of the model and methodology presented, makes them suitable to attack analogous problems in a simple manner after a convenient tuning.

We describe a rather simple optical experiment, which many students can easily carry out, but the theoretical explanation of which requires far-from-simple mathematical analysis and application of numerical methods. A thin vertical rod, partially immersed in a liquid-filled transparent cylindrical container, is moved from the centre toward the wall and observed laterally. As it moves, the part seen through the air and the part seen through the water start to separate, so that at a certain distance from the centre the lower part of the rod becomes invisible. We show that this happens at the distance for which the refracted ray that reaches the observer's eye is along the tangent to the surface of a cylinder. We derive the expression for this distance as a function of the index of refraction and ratio d/r, where d is the distance of the observer from the surface and r is the radius of the container. The locus of image positions is determined by evaluating the intersections of pairs of close rays from the rod which reach the observer's eye after refraction at the surface of the container.