Influence of Laboratory Generated Turbulence on Phase Fluctuations of a Laser Beam

An experiment is performed the aim of which is to investigate the phase fluctuations of a laser beam artificially generated thermal turbulence. This is achieved by observing the displacements of a fringe pattern obtained by means of a Mach-Zehnder interferometer. The temporal decay of the mean square refractive index fluctuation is studied. An interpretation of the results is given on the basis of the theory of an isotropic turbulent scalar field

Influence of Thermal Turbulence in a Convective Ascending Stream on Phase Fluctuations of a Laser Beam

The effects of thermal turbulence on the phase fluctuations of a laser beam are investigated in laboratory. The turbulent region created by means of a horizontal heated Nichrome grid is made to shift upwards owing to the convective motion. A Mach-Zehnder interference experiment is performed in which two beams from a laser source are superimposed after crossing the turbulent region. The displacements of the fringe pattern allow one to study the temporal decay of the mean square refractive index fluctuation. An interpretation of the results is given on the basis of the theory of an isotropic turbulent scalar field

Alteración de los monumentos graníticos en la provincia de La Coruña: datos preliminares

[Resumen] Se estudian una serie de edificios monumentales de la provincia de la Coruña construidos con materiales graniticos distribuidos por todo su territorio, tanto en el interior como en la zona costera. El objeto del trabajo es el de evaluar el estado de alteración de dichos edificios y conocer las principales causas y mecanismos que la producen Se ha encontrado que presentan diferentes formas de alteración según la parte del edificio que se considere y el tamaño de grano del material.[Résumé] On á etudié une serie de batiments monumentales á la province de la Coruña construits avec des materiels granitiques distribués dans tout le territoire tant al'interieur cornme á la zone de la cote. L'objet du travail c'est l'evaluation de l'etat d'altération de ces batiments et connaitre les principaux motifs et mechanismes qui la produissent. On á trouvé qu' ils pr~sent differents formes d'alteration selon la part du batiment qu' on considere et la grandeur des grains du materiel

Preparing and probing atomic number states with an atom interferometer

We describe the controlled loading and measurement of number-squeezed states and Poisson states of atoms in individual sites of a double well optical lattice. These states are input to an atom interferometer that is realized by symmetrically splitting individual lattice sites into double wells, allowing atoms in individual sites to evolve independently. The two paths then interfere, creating a matter-wave double-slit diffraction pattern. The time evolution of the double-slit diffraction pattern is used to measure the number statistics of the input state. The flexibility of our double well lattice provides a means to detect the presence of empty lattice sites, an important and so far unmeasured factor in determining the purity of a Mott state

Absorption Effects due to Spin in the Worldline Approach to Black Hole Dynamics

We generalize the effective point particle approach to black hole dynamics to include spin. In this approach dissipative effects are captured by degrees of freedom localized on the wordline. The absorptive properties of the black hole are determined by correlation functions which can be matched with the graviton absorption cross section in the long wavelength approximation. For rotating black holes, superradiance is responsible for the leading contribution. The effective theory is then used to predict the power loss due to spin in the dynamics of non-relativistic binary systems. An enhancement of three powers of the relative velocity is found with respect to the non-rotating case. Then we generalize the results to other type of constituents in the binary system, such as rotating neutron stars. Finally we compute the power loss absorbed by a test spinning black hole in a given spacetime background.Comment: 17 pages, 2 figures. v2 Typos and misprints fixe

Sublattice addressing and spin-dependent motion of atoms in a double-well lattice

We load atoms into every site of an optical lattice and selectively spin flip atoms in a sublattice consisting of every other site. These selected atoms are separated from their unselected neighbors by less than an optical wavelength. We also show spin-dependent transport, where atomic wave packets are coherently separated into adjacent sites according to their internal state. These tools should be useful for quantum information processing and quantum simulation of lattice models with neutral atoms