Quantum effects in the collective light scattering by coherent atomic recoil in a Bose-Einstein condensate

We extend the semiclassical model of the collective atomic recoil laser (CARL) to include the quantum mechanical description of the center-of-mass motion of the atoms in a Bose-Einstein condensate (BEC). We show that when the average atomic momentum is less than the recoil momentum $\hbar\vec q$, the CARL equations reduce to the Maxwell-Bloch equations for two momentum levels. In the conservative regime (no radiation losses), the quantum model depends on a single collective parameter, $\rho$, that can be interpreted as the average number of photons scattered per atom in the classical limit. When $\rho\gg 1$, the semiclassical CARL regime is recovered, with many momentum levels populated at saturation. On the contrary, when $\rho\le 1$, the average momentum oscillates between zero and $\hbar\vec q$, and a periodic train of $2\pi$ hyperbolic secant pulses is emitted. In the dissipative regime (large radiation losses) and in a suitable quantum limit, a sequential superfluorescence scattering occurs, in which after each process atoms emit a $\pi$ hyperbolic secant pulse and populate a lower momentum state. These results describe the regular arrangement of the momentum pattern observed in recent experiments of superradiant Rayleigh scattering from a BEC.Comment: submitted for publication on Phys. Rev.

Batch fabrication of cluster assembled microarrays for chemical sensing

nanomanufacturing and microfabrication parallel processing oxide nanoparticles industrial processesDeposition of clusters from the gas phase is becoming an enabling technology for the production of nanostructured devices. Supersonic clusters beam deposition (SCBD) has been shown as a viable route for the production of nanostructured thin films. By using SCBD and by exploiting aerodynamical effects typical of supersonic beams it is possible to obtain very high deposition rates with a control on neutral cluster mass distribution, allowing the deposition of thin films with tailored nanostructure. Due to high deposition rates, high lateral resolution, low temperature processing, SCBD can be used for the integration of cluster-assembled films on micro- and nanofabricated platforms with limited or no post-growth processing. Here we present the industrial opportunities for batch fabrication of gas sensor microarrays based on transition metal oxide nanoparticles deposited on microfabricated substrates

A New Estimator for Sensitivity Analysis of Model Output. An Application to the e-Business Readiness Composite Indicator.

Abstract not availableJRC.G-Institute for the Protection and the Security of the Citizen (Ispra

Classical and quantum description of the atomic motion in superradiant light scattering from Bose-Einstein condensates

A theory of coherent light scattering from an elongated Bose-Einstein condensate exposed to an off-resonant laser beam is presented. The model describes the emission of two superradiant pulses along the sample's major axis simultaneous with the formation of a bidimensional atomic grating inside the sample, as was observed in a recent MIT experiment [Inouye, S. et al., 1999, Science, 285, 571]. We predictions of the semiclassical model, in which the atomic motion is treated classically, are compared with these of the quantum model, obtained including the quantum mechanical description of the atomic motion. In the quantum limit the superradiant regime becomes a sequential process, in which during each collective scattering atoms emit a it hyperbolic secant pulse and populate an adjacent momentum state

Whole blood fatty acid composition differs in term versus mildly preterm infants: small versus matched appropriate for gestational age

To investigate the associations between whole blood fatty acid (FA) profile and restricted intrauterine growth, any small for gestational age (SGA) infant born in our maternity ward through 1 y was matched with two appropriate for gestational age (AGA), of the same GA +/- 0.5 wk, infants, further subdivided into term and preterm. Whole blood was collected at d 4 on a strip and FA % composition assessed by means of gas chromatography. The whole sample consisted of 28 SGA versus 56 AGA born at term and 20 SGA versus 40 AGA born preterm at around 35 wks. Parent FA of the n-6 and n-3 FA families were higher in preterm groups, whereas docosahexaenoic acid was higher in term AGA (median % values, 3.9 versus 3.7 in term SGA, 2.8 in preterm AGA, and 2.5 in preterm SGA, p < 0.001). Term AGA had markedly higher values for the docosahexaenoic acid/alpha-linolenic acid ratio (median value: 91, versus 18 in term SGA, 12 in preterm AGA, and 10 in preterm SGA, p < 0.001). Term SGA had significantly lower levels of total monounsaturated FA and higher levels of eicosapentaenoic acid. Therefore, the 4-d whole blood FA pattern is associated with both GA and birth weight

Benefits of breastfeeding in cystic fibrosis : a single-centre follow-up survey

AIM: To study the effect of breastfeeding (BF) on growth, lung function and number of infections during the first 3 years of life in children with cystic fibrosis (CF). MATERIAL AND METHODS: One hundred forty-six CF patients, 5-18 years old, were recruited at their annual care visit. Information about infant feeding, psychosocial and socioeconomic conditions and smoking exposure was obtained by interviews. Anthropometric parameters at 1 year of age and the number of infections and hospitalisations during the first 3 years of life were obtained from clinical charts. Anthropometrics and pulmonary function parameters were obtained at enrollment. RESULTS: In CF patients, particularly those with pancreatic insufficiency, the prevalence of BF was lower than the general Italian population. After multivariate analysis patients with prolonged BF showed higher values of CED expiratory volume in 1 sec (FEV-1) (p = 0.001) and a lower number of infections during the first 3 years of life (p = 0.098). CONCLUSION: Prolonged BF is beneficial in children with CF and may protect them against decline of pulmonary function. Particular attention should be paid to promote BF in infants with C