Vol. 64 No. 2 Jul-Dec (2018): Revista Mexicana de Física E

The present work is a review of the chronological development of the laser invention, starting from the theoretical proposal of stimulated
emission to the invention of the first laser device. We present the most relevant research papers and discuss the difficulties that had to be faced, including the disputes that occurred at the time of registering the laser patent. Besides, the theoretical principles that make possible the emission of the laser are studied, describing the population inversion in a system of three levels of energy from a mathematical model and the architecture that must have a laser linear cavity.

A brief review of 3 + 1 formalism in General Relativity is presented, introducing innovative conventions and notation elements which make it easier to deal with all of the tensorial projections involved in this formalism. Also, useful 3 + 1 expressions for manipulation of indexes (contraction, symmetrization, anti-symmetrization), tensorial producs and the covariant derivative of arbitrary tensors are obtained.

We study the problem of a charged particle in a uniform magnetic field with two different gauges, known as Landau and symmetric gauges. By using a similarity transformation in terms of the displacement operator we show that, for the Landau gauge, the eigenfunctions for this problem are the harmonic oscillator number coherent states. In the symmetric gauge, we calculate the SU(1; 1) Perelomov number coherent states for this problem in cylindrical coordinates in a closed form. Finally, we show that these Perelomov number coherent states are related to the harmonic oscillator number coherent states by the contraction of the SU(1; 1) group to the Heisenberg-Weyl group.

In this work, the design and construction of a didactic experimental equipment to visualize the fluid flow behavior in the laminar, transition and turbulent regimes is presented; as well as the ability to measure and display the respective Reynolds number (Re) of each flow; current educational equipments have limited or null capacity in this regard. The equipment was designed taking into account the basic laws of fluids such as mass, momentum and energy conservation. The analytical calculations were numerically validated using the finite element method (FEM), for which the Ansys software was used in its Ansys@ Parametric Design Language (APDL) and Workbench platforms. Solidworks tools for conceptual design and Stratasys Catalist for three dimension (3D) printing were used. Additionally, hardware was implemented for the step of measuring the flow velocity, temperature and Re calculation. The apparatus is a valuable resource in fluid flow visualization since it permits to read several fluid parameters immediately from a display.

Exact solutions of the Maxwell equations for the electromagnetic fields inside and outside a spherical surface, with time alternating magnetic or electric dipole source distributions, are constructed as alternatives to the respective familiar point-dipole solutions in undergraduate and graduate books. These solutions are valid for all positions, inside and outside the sphere, including the quasi-static, induction and radiation zones; the solutions inside make the difference from the point-dipole solutions; the definitions of the dynamic dipole moments must be based on the ordinary spherical Bessel functions for the solutions outside, and on the outgoing spherical Hankel functions for the solutions inside,
instead of the powers of the radial coordinate as solutions of the Laplace equation valid for the static case. The solutions for the resonating cavities are associated with the nodes of the spherical Bessel function for the TE modes of the magnetic dipole source, and with the extremes of the product of the radial coordinate times the same spherical function for the TM modes of the electric dipole source; both conditions also guarantee the vanishing of the fields outside.

In this work, we examine the elastic scattering cross sections of 13C on 12C, 16O, 28Si and 208Pb target nuclei at different incident energies. For the first time, we apply six types of proximity potentials such as Broglia andWinther 1991 (BW 91), AageWinther (AW95), Christensen and Winther 1976 (CW 76), Bass 1973 (Bass 73), Bass 1977 (Bass 77) and Bass 1980 (Bass 80) in order to obtain the real part of the optical potential. The imaginary part is taken as the Woods-Saxon potential. Theoretical results are compared with each other as well as the experimental data.

The excitation of surface plasmons in metallic spheres is studied theoretically. The metallic sphere is supposed to be of the Drude type. The modes excitations for metallic spheres, like the dielectric spheres are observed as peaks in the total scattering cross section. Under excitation condition, the modes are behaved as waves that propagates along the circumference, but in the sphere, its intensity is highly confined to the surface. The number of modes observed depends on the radius of the sphere.

An outline of topics that constitute a graduate course on interaction of radiation with matter is presented. The list covers the physical events that produce structural changes in materials, and some of the techniques used to study them. Starting with the initial binary event, a sequence of typical processes that take place as radiation passes through matter is described, with emphasis on atomic displacements and the evolution of cascades. Procedures that involve large numbers of events and use statistical methods, like Monte Carlo and molecular dynamics, are sketched, leading to the description of macroscopic effects, and eventually continuum theories.

An important feature of quantum computing is its inherent paralellism, allowing to process an exponential number of basic transforms with just a linear number of qubits. The Deutsch-Jozsa algorithm exemplifies the computational complexity reduction. This work reports the implementation and execution of the Deutsch-Josza quantum algoritm in GAMA, a programming language for quantum computing simulation developed by ourselves. Through this simulation, it is possible to explore all the components involved by tracing all the different configurations that each component may take.

In this paper we will analyze the problem of blackbody radiation in an effective 4D scenario that arises from the 5D free gauge field, where the fifth dimension is compactified to a circle. The starting point is the Kaluza-Klein decomposition of the 5D gauge field action into two sectors in four dimensions: the first sector contains a massless gauge field, while the second sector yields an infinite set of massive gauge fields. Both sectors contribute to Stefan-Boltzmann’s law. By contrasting the experimental data with those obtained theoretically, a bound is obtained for the parameter associated with the scenario.

In this article, we study the operation and basic elements in a passively mode-locked fiber ring laser (PML-FRL), emphasizing the saturable absorber (SA) effect seen as a nonlinear filter in transmission, which is produced by the non-linear polarization rotation (NPR) and a linear polarizer. Besides, we employ a technique of 3D mapping measurements for characterizing ultra-short pulse dynamics.

Describing the motion of the classical simple pendulum is one of the aims in every undergraduate classical mechanics course. Its analytical solutions are given in terms of elliptic functions, which are doubly periodic functions in the complex plane. The independent variable of the solutions is time and it can be considered either as a real variable or as a purely imaginary one, which introduces a rich symmetry structure in the space of solutions. When solutions are written in terms of the Jacobi elliptic functions this symmetry is codified in the functional form of its modulus, and is described mathematically by the six dimensional coset group Γ=Γ(2) where Γ is the modular group and Γ(2) is its congruence subgroup of second level. A discussion of the physical consequences that this symmetry has on the motions of the simple pendulum is presented in this contribution and it is argued they have similar properties to the ones termed as duality symmetries in other areas of physics, such as field theory and string theory. Thus by studying deeper a very familiar mechanical system, it is possible to get an insight to more abstract physical and mathematical concepts. In particular a single solution of pure imaginary time for all allowed values of the total mechanical energy is given and obtained as the S-dual of a single solution of real time, where S stands for the S generator of the modular group.

The response of a fluid to deformation by shear stress is known as shear viscosity. This concept arises from a macroscopic view and was first introduced by Sir Isaac Newton. Nonetheless, a fluid is a series of moving molecules that are constrained by the shape of the container. Such a view begs the treatment of viscosity from a microscopic or molecular view, a task undertaken by both Einstein and Smoluchowski independently. Here we revisit the concept of viscosity and experimentally verify that the viscosity at a molecular level, which describes the drag force, is the same as the macroscopic shear viscosity; hence, bridging different length- and time-scales. For capturing the shear stress response of a fluid, we use classical rheometry; at a molecular level we use probe diffusion to determine the local viscosity from
the translational and rotational motions. In these cases, we use Fluorescence Correlation Spectroscopy and Time Resolved Fluorescence, respectively. By increasing the osmolyte (Glucose-D) concentration, we change the viscosity and find that these methods provide a unified view of viscosity, bridging the gap between the macroscopic and nanoscale regimes. Moreover, Glucose’s viscosity follows a scaling factor
more commonly associated to solutions of branched polymer because the probe dimensions are comparable to the dimensions of the osmolyte that exerts the drag.

In this paper, the velocity and acceleration of four water rockets is determined, using the least squares method and the Euler’s method. The position and time data are obtained from the analysis of slow-motion videos of the launch of the rockets, processed with the video analyzer software “Tracker”. This experiment is proposed as a pedagogical tool for the exploration by students of high school and first semester of sciencie and engineering of basic concepts of kinematics and dynamics in systems with variable mass and acceleration.

This paper describes the design and implementation of an experimental system that estimates the electric power that can be produced by the angular motion showing the fundamental principles of mechanical-into-electrical energy conversion, which are the operation main basis of electromechanical devices such as wind turbines. Some theoretical concepts related with curricular subjects such as Electric mchenary, Physics, Renewable Energies, Power Electronics and Microcontrollers, were verified by Science students that participated in this project achievement. The main aim of this work is to show a simplified system development for didactic applications that can be mounted at indoor conditions and can be constructed from a set of basic and cheap electrical components.

Almost half a century before Einstein expounded his general theory of relativity, the English mathematicianWilliam Kingdon Clifford argued that space might not be Euclidean and proposed that matter is nothing but a small distortion in that spatial curvature. He further proposed that matter in motion is not more than the simple variation in space of this distortion. In this work, we conjecture that Clifford went further than his aforementioned proposals, as he tried to show that matter effectively curves space. For this purpose he made an unsuccessful observation on the change of the plane of polarization of the skylight during the solar eclipse of December 22, 1870 in Sicily.