Control of Optical Dynamic Memory Capacity of an Atomic Bose-Einstein Condensate

Light storage in an atomic Bose-Einstein condensate is one of the most practical usage of these coherent atom-optical systems. In order to make them even more practical, it is necessary to enhance our ability to inject multiple pulses into the condensate. In this paper, we report that dispersion of pulses injected into the condensate can be compensated by optical nonlinearity. In addition, we will present a brief review of our earlier results in which enhancement of light storage capacity is accomplished by utilizing multi-mode light propagation or choosing an optimal set of experimental parameters.Comment: 4 figures, 11 page

Investigación sobre la composición química, minerales y ácidos grasos de dos cultivares de almendra cultivados como orgánico y convencional en el sudeste de Turquía

Organic farming is a human and environment friendly production system that is based on soil fertility and food safety without using chemical fertilizers and pesticides in production, aiming to re-establish the deteriorated ecological balance as a result of harmful production practices. Organic products attract the interest of consumers as they are strongly perceived as healthier products compared to conventional food. This study aimed to determine the differences in chemical, mineral, and fatty acid characteristics between conventionally and organically cultivated Ferragnes and Ferraduel almond cultivars. When conventional and organic almonds were evaluated in terms of fatty acids, proximate compositions, and minerals, crude oil and Mg were statistically insignificant, while Cu was significant (P < 0.05) and all others were quite significant (P < 0.001). Total sugar was higher in organic samples compared to conventional samples in both cultivars. The crude oil and linoleic acid (12.93% for Ferragnes and 14.99% for Ferraduel) were higher in conventional samples but oleic acid (78.9% for Ferragnes and 81.08% for Ferraduel) was higher in organic samples. In addition, organic samples contained higher Mg and Fe but lower P, K, Ca, Na, Zn, Mn and Cu when compared with conventional samples. The results indicate that conventionally cultivated almonds present higher mineral content and lower fatty acid value compared to organically cultivated almonds.La agricultura orgánica es un sistema de producción amigable con el ser humano y el medio ambiente, basado en la fertilidad del suelo y la seguridad alimentaria. Este sistema suele prescindir del uso de fertilizantes químicos y pesticidas en la producción, con el objetivo de prefijar el equilibrio ecológico previamente destruido como resultado natural de prácticas de producción incorrectas. Los productos orgánicos están atrayendo cada vez más el interés de los consumidores ya que se perciben como productos más saludables en comparación con los alimentos convencionales. Este estudio tenía como objetivo determinar las diferencias en las características químicas, minerales y ácidos grasos existentes entre los cultivares de almendra de Ferragnes y de Ferraduel, cultivados tanto convencionalmente como orgánicamente. Cuando se evaluaron las almendras convencionales y las orgánicas en términos de ácidos grasos, composiciones proximal y minerales, el aceite crudo y el Mg fueron estadísticamente insignificantes, mientras que los valores de Cu fue significativo (P < 0.05) y todos los demás fueron bastante significativos (P < 0.001). El azúcar total fue mayor en muestras orgánicas en comparación con muestras convencionales en ambos cultivares. El aceite crudo y el ácido linoleico (12.93% para Ferragnes y 14.99% para Ferraduel) fue mayor en muestras convencionales, pero el ácido oleico (78.9% para Ferragnes y 81.08% para Ferraduel) fue mayor en muestras orgánicas. Además, las muestras orgánicas contenían mayor Mg y Fe pero menor P, K, Ca, Na, Zn, Mn y Cu cuando se compararon con las muestras convencionales. Los resultados indican que las almendras convencionales presentan mayor contenido mineral y menor valor de ácidos grasos en comparación con las cultivadas orgánicamente

Enhancing capacity of coherent optical information storage and transfer in a Bose-Einstein condensate

Coherent optical information storage capacity of an atomic Bose-Einstein condensate is examined. Theory of slow light propagation in atomic clouds is generalized to short pulse regime by taking into account group velocity dispersion. It is shown that the number of stored pulses in the condensate can be optimized for a particular coupling laser power, temperature and interatomic interaction strength. Analytical results are derived for semi-ideal model of the condensate using effective uniform density zone approximation. Detailed numerical simulations are also performed. It is found that axial density profile of the condensate protects the pulse against the group velocity dispersion. Furthermore, taking into account finite radial size of the condensate, multi-mode light propagation in atomic Bose-Einstein condensate is investigated. The number of modes that can be supported by a condensate is found. Single mode condition is determined as a function of experimentally accessible parameters including trap size, temperature, condensate number density and scattering length. Quantum coherent atom-light interaction schemes are proposed for enhancing multi-mode light propagation effects.Comment: 12pages. Laser Physics, in pres

Direct observation of LO phonon-plasmon coupled modes in the infrared transmission spectra of n-GaAs and n-InxGa1-xAs epilayers

The infrared transmission spectrum of Si-doped molecular beam epitaxy (MBE)-grown GaAs epilayers, 2-2.5-mum thick, measured in the oblique (Berreman) geometry, revealed distinct minima in p polarization. Given epilayer thickness \u3c reststrahlen wavelength, the minima are identified as the zone-center transverse optic phonon (omega(TO)) and the high-frequency LO phonon-plasmon coupled mode (omega(+)). Analysis of the experimental data yielded free-carrier concentrations ranging from 2.5x10(17) to 1.4x10(18) cm(-3). The same technique with MBE-grown Si-doped In0.53Ga0.47As epilayers (0.5-1 mum thick) yielded omega(+) modes corresponding to free-carrier concentrations of 8.2x10(16)-2.7x10(19) cm(-3). The observations of the transmission minima in the Berreman geometry and their interpretation demonstrate a direct and simple method for deducing free-carrier concentrations over a wide range

Soap Froths and Crystal Structures

We propose a physical mechanism to explain the crystal symmetries found in macromolecular and supramolecular micellar materials. We argue that the packing entropy of the hard micellar cores is frustrated by the entropic interaction of their brush-like coronas. The latter interaction is treated as a surface effect between neighboring Voronoi cells. The observed crystal structures correspond to the Kelvin and Weaire-Phelan minimal foams. We show that these structures are stable for reasonable areal entropy densities.Comment: 4 pages, RevTeX, 2 included eps figure