Double barrier potentials for matter-wave gap solitons

We investigate collisions of solitons of the gap type, supported by a lattice potential in repulsive Bose-Einstein condensates, with an effective double-barrier potential that resembles a Fabry-Perot cavity. We identify conditions under which the trapping of the entire incident soliton in the cavity is possible. Collisions of the incident soliton with an earlier trapped one are considered too. In the latter case, many outcomes of the collisions are identified, including merging, release of the trapped soliton with or without being replaced by the incoming one, and trapping of both solitons.Comment: 5 pages, 4 figure

Utilització del recurs qüestionari tant per avaluació de la qualitat de la docència (SEEQ) com eina d’autoavaluació

El recurs d’introduir un qüestionari en Atenea pot utilitzar-se per avaluar la qualitat de la docència que oferim als estudiants mitjançant dos tipus de qüestionaris diferents. Per una banda al finalitzar el curs se’ls crea un qüestionari amb la coneguda enquesta anomenada SEEQ (Student Evaluations of Educational Quality). Per altre banda es generen qüestionaris autoavaluatius que un cop resolts els diu als estudiants la nota que tenen. Aquest es generen per diferents mòduls de dos assignatures i s’activen en diferents moments del curs. Per la SEEQ l’avaluació dels resultats es realitza fora de atenea utilitzant una eina del Excel. Per als qüestionaris s’estudien les preguntes de resposta curta, les d’aparellament, les numèriques i les calculades. Es pretén generar una base de preguntes per cada pregunta del qüestionari amb l’objectiu que sigui diferent per cada estudiant. A més, es pretén no utilitzar les preguntes de resposta múltiple. L’objectiu d’aquest treball és mostrar les lliçons apreses amb la utilització d’aquests dos tipus de qüestionarisPeer Reviewe

Deducción de compras a monotributistas en el impuesto a las ganancias

Fil: Corbalán, Marcelo A. Universidad Nacional de Mar del Plata. Facultad de Ciencias Económicas y Sociales; Argentina.Fil: Gómez, Melisa. Universidad Nacional de Mar del Plata. Facultad de Ciencias Económicas y Sociales; Argentina

Full polarization chaos in a pump-polarization modulated isotropic cavity laser

We study the dynamic behavior of an optically pumped J = 0 → J = 1 → J = 0 laser operating with an isotropic ring cavity and a linearly polarized pump field whose direction of polarization is modulated by the sinusoidal law θ(t) = m sin Ωt. Modulation frequencies Ω of the same order of magnitude as the transverse relaxation rate of the laser transition are considered here. At large enough modulation amplitudes, and for a detuned cavity, we obtain fully developed polarization chaos, which affects both the ellipticity and the orientation of the polarization ellipse as well as the laser intensity

Conical refraction healing after partially blocking the input beam

In conical refraction, when a focused Gaussian beam passes along one of the optic axes of a biaxial crystal it is transformed into a pair of concentric bright rings at the focal plane. We demonstrate both theoretically and experimentally that this transformation is hardly affected by partially blocking the Gaussian input beam with an obstacle. We analyze the influence of the size of the obstruction both on the transverse intensity pattern of the beam and on its state of polarization, which is shown to be very robust

Atomtronics with holes: Coherent transport of an empty site in a triple well potential

We investigate arrays of three traps with two fermionic or bosonic atoms. The tunneling interaction between neighboring sites is used to prepare multi-site dark states for the empty site, i.e., the hole, allowing for the coherent manipulation of its external degrees of freedom. By means of an ab initio integration of the Schr\"odinger equation, we investigate the adiabatic transport of a hole between the two extreme traps of a triple-well potential. Furthermore, a quantum-trajectory approach based on the de Broglie-Bohm formulation of quantum mechanics is used to get physical insight into the transport process. Finally, we discuss the use of the hole for the construction of a coherent single hole diode and a coherent single hole transistor.Comment: 9 pages, 6 figure

Polarization phase gate with a tripod atomic system

We analyze the nonlinear optical response of a four-level atomic system driven into a tripod configuration. The large cross-Kerr nonlinearities that occurr in such a system are shown to produce nonlinear phase shift of order $\pi$. Such a substantial shift may be observed in a cold atomic gas in a magneto-optical trap where it coupl be fasibly exploited towards the realization of a polarization quantum phase gate. The experimental feasibility of such a gate is here examined in detail.Comment: Corrected versio

Generation of entangled photon pairs in optical cavity-QED: Operating in the bad cavity limit

We propose an optical cavity-QED scheme for the deterministic generation of polarization entangled photon pairs that operates with high fidelity even in the bad cavity limit. The scheme is based on the interaction of an excited four-level atom with two empty optical cavity modes via an adiabatic passage process. Monte-Carlo wave function simulations are used to evaluate the fidelity of the cavity-QED source and its entanglement capability in the presence of decoherence. In the bad cavity limit, fidelities close to one are predicted for state-of-the-art experimental parameter values.Comment: 9 pages and 5 figure

Contribución al estudio reológico del néctar de albaricoque

The rheological behaviour of the apricot nectar has been studied. The equations which bind the shear-stress with the angular rate of the viscosimeter, obtained from the corresponding rheograms, and also that ones which establish the dependance between the apparent viscosity of diluted nectars and the corresponding pulp concentration. Through the study of the temperature influence on the rheological parameters were obtained the corresponding equations of exponential type such as K = K0 • eA/T where K0 = constant which is distinctive for each nectar, T = Kelvin temperature and A = constant, whose value is ΔE/R, where ΔE is the activation energy for the flow and R = Gas general constant.Se ha estudiado el comportamiento reológico del néctar de albaricoque estableciéndose las ecuaciones que ligan los esfuerzos cortantes con la velocidad angular del viscosímetro, deducidas de los reogramas correspondientes, y las que relacionan la viscosidad aparente de néctares diluidos del anterior con su concentración en pulpa. Mediante el estudio del efecto de la temperatura sobre los parámetros reológicos se han deducido ecuaciones del tipo K = K0 exp(A/T), donde K0 = cte característica del néctar, T = ta absoluta y A = cte, cuyo valor es ΔE/R, siendo ΔE la energía de activación del flujo y R la cte de los gases

The cephalopod prey of the Weddell seal, Leptonychotes weddellii, a biological sampler of the Antarctic marine ecosystem

Weddell seals, Leptonychotes weddellii, are important apex predators in the food web of the Antarctic marine ecosystem. However, detailed information on their trophic relationships with cephalopods is scarce. Moreover, cephalopods play a key role in the marine environment, but knowledge of their feeding habits is limited by lack of data. Here, we have combined the use of this seal as a biological sampler together with measurements of the stable isotopic signature of the beaks of their cephalopod prey. Thus, the aims of the present study were: (1) to examine in detail the cephalopod portion of the diet of Weddell seals by means of scat analysis and (2) to assess the habitat use and trophic level of the different cephalopod prey taxa identified. From January to February 2009, a total of 48 faecal droppings were collected at Hope Bay, Antarctic Peninsula. Cephalopods were mainly represented by beaks (n = 83) which were identified to the lowest possible taxonomic level. Furthermore, subsamples of beaks were separated for further isotopic analysis. Relative abundance of stable isotopes of carbon (δ13C) and nitrogen (δ15N) was determined by continuous-flow isotope-ratio mass spectrometry. Cephalopods were represented uniquely by octopods of the subfamily Eledoninae. Pareledone turqueti was the dominant prey species followed by the papillated Pareledone species group and Adelieledone polymorpha. We conclude that Weddell seals preyed primarily on benthic prey resources. Furthermore, the relatively similar δ13C and δ15N values in beaks of the three octopod prey taxa suggest that these share the same type of habitat and occupy similar trophic level positions