Novel Ferromagnetic Atom Waveguide with in situ loading

Magneto-optic and magnetostatic trapping is realized near a surface using current carrying coils wrapped around magnetizable cores. A cloud of 10^7 Cesium atoms is created with currents less than 50 mA. Ramping up the current while maintaining optical dissipation leads to tightly confined atom clouds with an aspect ratio of 1:1000. We study the 3D character of the magnetic potential and characterize atom number and density as a function of the applied current. The field gradient in the transverse dimension has been varied from < 10 G/cm to > 1 kG/cm. By loading and cooling atoms in-situ, we have eliminated the problem of coupling from a MOT into a smaller phase space.Comment: 4 pages, 4 figure

Bose-Einstein Condensates in the Large Gas Parameter Regime

Bose-Einstein condensates of 10$^4$ $^{85}$Rb atoms in a cylindrical trap are studied using a recently proposed modified Gross-Pitaevskii equation. The existence of a Feshbach resonance allows for widely tuning the scattering length of the atoms, and values of the peak gas parameter, $x_{pk}$, of the order of 10$^{-2}$ can be attained. We find large differences between the results of the modified Gross-Pitaevskii and of the standard Thomas-Fermi, and Gross-Pitaevskii equations in this region. The column densities at $z=0$ may differ by as much as $\sim 30$ and the half maximum radius by $\sim 20$. The scattering lengths estimated by fitting the half maximum radius within different approaches can differ by $\sim 40$.Comment: 4 LaTeX pages, 2 figure

On the suppression of the diffusion and the quantum nature of a cavity mode. Optical bistability; forces and friction in driven cavities

A new analytical method is presented here, offering a physical view of driven cavities where the external field cannot be neglected. We introduce a new dimensionless complex parameter, intrinsically linked to the cooperativity parameter of optical bistability, and analogous to the scaled Rabbi frequency for driven systems where the field is classical. Classes of steady states are iteratively constructed and expressions for the diffusion and friction coefficients at lowest order also derived. They have in most cases the same mathematical form as their free-space analog. The method offers a semiclassical explanation for two recent experiments of one atom trapping in a high Q cavity where the excited state is significantly saturated. Our results refute both claims of atom trapping by a quantized cavity mode, single or not. Finally, it is argued that the parameter newly constructed, as well as the groundwork of this method, are at least companions of the cooperativity parameter and its mother theory. In particular, we lay the stress on the apparently more fundamental role of our structure parameter.Comment: 24 pages, 7 figures. Submitted to J. Phys. B: At. Mol. Opt. Phy

Informe n° 38 - SITUACIÓN FITOSANITARIA - Región Centro Norte de Córdoba 08 de febrero de 2017

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Informe de Situación Fitosanitaria Región Centro Norte de Córdoba

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Informe de SITUACIÓN FITOSANITARIA - Región Centro Norte de Córdoba 19 de febrero de 2016

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Informe de SITUACIÓN FITOSANITARIA - Región Centro Norte de Córdoba 21 de diciembre de 2015

Avanza en la región la implantación de los cultivos de soja y de maíz, hasta el momento se ha sembrado aproximadamente el 32 % del área de maíz y el 67% de soja en el centro norte de la provincia(datos extraídos del Panorama Agrícola Semanal de la Bolsa de Cereales - relevamiento al 17/12/2015).Al igual que las últimas campañas, las consultas más frecuentes recibidas hasta el momento se basan en diferenciar síntomas similares a MOR en soja y en determinar que son los "lunares blancos" que se desarrollan en el cultivo de maíz.A esto se le suma una gran cantidad de consultas por síntomas "raros" producidos por diferentes herbicidas que han causado fitotoxicidad. La utilización de ingredientes activos que hasta hace poco no se usaban, así como sus combinaciones, y dosis para el control de malezas tolerantes o resistentes, han generado muchas preguntas por sintomatologías a las cuales deberemos aprender a reconocer para registrar en nuestros lotes.A continuación brindamos información que ayuda a responder estas consultas."Al igual que años anteriores ponemos nuestro esfuerzo en brindarles esta herramienta que son los Informes, esperando que les ayude para estar atentos al monitoreo, al diagnóstico y al manejo de las enfermedades en los momentos oportunos, para así poder acercarse al rendimiento potencial esperado en cada cultivo"

Modification of radiation pressure due to cooperative scattering of light

Cooperative spontaneous emission of a single photon from a cloud of N atoms modifies substantially the radiation pressure exerted by a far-detuned laser beam exciting the atoms. On one hand, the force induced by photon absorption depends on the collective decay rate of the excited atomic state. On the other hand, directional spontaneous emission counteracts the recoil induced by the absorption. We derive an analytical expression for the radiation pressure in steady-state. For a smooth extended atomic distribution we show that the radiation pressure depends on the atom number via cooperative scattering and that, for certain atom numbers, it can be suppressed or enhanced.Comment: 8 pages, 2 Figure

Informe de situación fitosanitaria - Región Centro Norte de Córdoba Informe nº 45 - 20 de Enero de 2019

El contexto ambiental de la presente campaña ha sido opuesto a lo registrado en el anterior ciclo agrícola. Se llega a un Enero con buenas precipitaciones y, en algunos casos, hasta excesivas. Las temperaturas tampoco se han comportado en forma normal, y se han registrado alternancias de altas y bajas muy marcadas.Se debe tener en cuenta que estos factores climáticos son altamente conducentes y favorables a la presencia y desarrollo de enfermedades.Tanto en Soja como en Maíz las siembras se han registrado con normalidad. En nuestra región se observan cultivos en estados vegetativos y reproductivos con un desarrollo satisfactorio.Los distintos estadios fenológicos de los cultivos y el ambiente conducente generan una expresión variada de enfermedades en cada cultivo y los monitoreos se hacen más que necesarios

Probing the energy bands of a Bose-Einstein condensate in an optical lattice

We simulate three experimental methods which could be realized in the laboratory to probe the band excitation energies and the momentum distribution of a Bose-Einstein condensate inside an optical lattice. The values of the excitation energies obtained in these different methods agree within the accuracy of the simulation. The meaning of the results in terms of density and phase deformations is tested by studying the relaxation of a phase-modulated condensate towards the ground state.Comment: 5 pages, 5 figure