Conversion of 40^{40}K-87^{87}Rb mixtures into stable molecules

We study the conversion of $^{40}$K and $^{87}$Rb atoms into stable molecules through the stimulated Raman adiabatic passage (STIRAP) in photoassociation assisted with Feshbach resonance. Starting with the mean-field Langrange density, we show that the atom-to-molecule conversion efficiency by STIRAP aided by Feshbach resonance is much larger than that by bare Feshbach resonance. We also study the influence of the population imbalance on the atom-to-molecule conversion.Comment: Revtex, 5 pages, 3 figures; version to appear in PRA (some content changed

Creating stable molecular condensate using a generalized Raman adiabatic passage scheme

We study the Feshbach resonance assisted stimulated adiabatic passage of an effective coupling field for creating stable molecules from atomic Bose condensate. By exploring the properties of the coherent population trapping state, we show that, contrary to the previous belief, mean-field shifts need not to limit the conversion efficiency as long as one chooses an adiabatic passage route that compensates the collision mean-field phase shifts and avoids the dynamical unstable regime.Comment: 4+\epsilon pages, 3 figure

Diversities in Diversity: Exploring Moroccan Migrants’ Livelihood in Genoa

It is a largely accepted idea that complexity and recent global phenomena have generated a multi-layered diversification process in Western societies. Migration phenomena are largely responsible for this process both in receiving European societies as well as in original sending countries. Migration has been and continues to be a ubiquitous human experience. Yet, while this fact has aided the understanding of the world as something other than a mosaic of distinct cultural spaces with clearly demarcated borders, it has not decreased the incomprehension, fear and suspicion with which non–European migrants are often greeted within the industrialised cities of Europe. This article deals with one aspect of this process that seems to be quite underestimated in media, public opinion and academia. It is the idea that “ethnicity” can be approached, explored and investigated as a heterogeneous and multi-faced form of diversity itself. This is what can be defined as “diversities within diversity”. Departing from the presentation of an empirical research in Genoa it will be possible to analyse these phenomena at two different levels: namely, in terms of methods and methodology. By focusing on the idea of livelihood and employing an approach based on “Tracing” techniques, different ways of acting and being Moroccan migrants in Genoa will be revealed, presented and discussed. This method newly integrates both quantitative and qualitative information. It will allow us to analyse the experience of livelihood in a way that will reveal the simultaneous existence of many underlying different invisible and unconscious social constructions as well as visible concrete and conscious expressions of everyday life. Disclosing how the same people in the same local context produce different “adaptive” strategies and lifestyles will lead to outline a potential conceptual methodological framework of reference based on an open/close principle. In this case ideas of openness and closeness will be assumed in a dialectical double-faced process. It is not only a matter of how systems can be defined open or closed by themselves, but also how the encounter and interplay of many different systems – generation of diversity - establish the conditions and limits within which different individuals can reproduce their culture as social actors- production of diversities. After having discussed the methodological implications of this approach it will be possible to draw some final theoretical considerations. If we believe that new ways of investigating social phenomena are a determinant in the way we describe, analyze, explain and understand their complexity, we should recognize that not only theory might generate and define what we call social reality but also vice-versa. Approaching the world out there in new ways might result in rethinking and adjusting the conceptual taxonomies that drive social scholars in their search for gaining and catching social reality. This principle becomes crucial if we want social sciences to be heuristically oriented, in other words if we want to develop the capacity to hand back positive analytical readings and comparisons of social phenomena as well as useful recommendations for policy makers.Migration, Italy, Morocco, Methodology, Tracing, Open/close Model

Nuclear halo and the coherent nuclear interaction

The unusual structure of Li11, the first halo nucleus found, is analyzed by the Preparata model of nuclear structure. By applying Coherent Nucleus Theory, we obtain an interaction potential for the halo-neutrons that rightly reproduces the fundamental state of the system.Comment: 9 pages Submitted to International Journal of Modern Physics E (IJMPE

Diversities in Diversity: Exploring Moroccan Migrants' Livelihood in Genoa

It is a largely accepted idea that complexity and recent global phenomena have generated a multi-layered diversification process in Western societies. Migration phenomena are largely responsible for this process both in receiving European societies as well as in original sending countries. Migration has been and continues to be a ubiquitous human experience. Yet, while this fact has aided the understanding of the world as something other than a mosaic of distinct cultural spaces with clearly demarcated borders, it has not decreased the incomprehension, fear and suspicion with which non European migrants are often greeted within the industrialised cities of Europe. This article deals with one aspect of this process that seems to be quite underestimated in media, public opinion and academia. It is the idea that ethnicity can be approached, explored and investigated as a heterogeneous and multi-faced form of diversity itself. This is what can be defined as diversities within diversity . Departing from the presentation of an empirical research in Genoa it will be possible to analyse these phenomena at two different levels: namely, in terms of methods and methodology. By focusing on the idea of livelihood and employing an approach based on Tracing techniques, different ways of acting and being Moroccan migrants in Genoa will be revealed, presented and discussed. This method newly integrates both quantitative and qualitative information. It will allow us to analyse the experience of livelihood in a way that will reveal the simultaneous existence of many underlying different invisible and unconscious social constructions as well as visible concrete and conscious expressions of everyday life. Disclosing how the same people in the same local context produce different adaptive strategies and lifestyles will lead to outline a potential conceptual methodological framework of reference based on an open/close principle. In this case ideas of openness and closeness will be assumed in a dialectical double-faced process. It is not only a matter of how systems can be defined open or closed by themselves, but also how the encounter and interplay of many different systems generation of diversity - establish the conditions and limits within which different individuals can reproduce their culture as social actors- production of diversities. After having discussed the methodological implications of this approach it will be possible to draw some final theoretical considerations. If we believe that new ways of investigating social phenomena are a determinant in the way we describe, analyze, explain and understand their complexity, we should recognize that not only theory might generate and define what we call social reality but also vice-versa. Approaching the world out there in new ways might result in rethinking and adjusting the conceptual taxonomies that drive social scholars in their search for gaining and catching social reality. This principle becomes crucial if we want social sciences to be heuristically oriented, in other words if we want to develop the capacity to hand back positive analytical readings and comparisons of social phenomena as well as useful recommendations for policy makers

Coherent population trapping in two-electron three-level systems with aligned spins

The possibility of coherent population trapping in two electron states with aligned spins (ortho-system) is evidenced. From the analysis of a three-level atomic system containing two electrons, and driven by the two laser fields needed for coherent population trapping, a conceptually new kind of two-electron dark state appears. The properties of this trapping are studied and are physically interpreted in terms of a dark hole, instead of a dark two-electron state. This technique, among many other applications, offers the possibility of measuring, with subnatural resolution, some superposition-state matrix-elements of the electron-electron correlation that due to their time dependent nature are inaccesible by standard measuring procedures.Comment: 10 pages and 4 figure

Slow Light amplification in a non-inverted gain medium

We investigate the propagation of a coherent probe light pulse through a three-level atomic medium (in the $\Lambda$--configuration) in the presence of a pump laser under the conditions for gain without inversion. When the carrier frequency of the probe pulse and the pump laser are in a Raman configuration, we show that it is possible to amplify a slow propagating pulse. We also analyze the regime in which the probe pulse is slightly detuned from resonance where we observe anomalous light propagation.Comment: 7 pages, 10 figures. To be published in Europhysics Letter

Steady state behaviour in atomic three-level lambda and ladder systems with incoherent population pumping

The steady state in three-level lambda and ladder systems is studied. It is well-known that in a lambda system this steady state is the coherent population trapping state, independent of the presence of spontaneous emission. In contrast, the steady state in a ladder system is in general not stable against radiative decay and exhibits a minimum in the population of the ground state. It is shown that incoherent population pumping destroys the stability of the coherent population trapping state in the lambda system and suppresses a previously discovered sharp dip in the steady state response. In the ladder system the observed minimum disappears in the presence of an incoherent pump on the upper transition.Comment: 4 pages, RevTex, 5 figures, to appear in Phys. Rev.

Coherent population trapping in quantized light field

A full quantum treatment of coherent population trapping (CPT) is given for a system of resonantly coupled atoms and electromagnetic field. We develop a regular analytical method of the construction of generalized dark states (GDS). It turns out that GDS do exist for all optical transitions $F_g\to F_e$, including bright transitions $F\to F+1$ and $F''\to F''$ with $F''$ a half-integer, for which the CPT effect is absent in a classical field. We propose an idea to use an optically thick medium with a transition $F''\to F''$ with $F'' \ge 3/2$ a half-integer as a ''quantum filter'', which transmits only a quantum light.Comment: revtex4, twocolumn, 6 pages, including 1 figur