853 research outputs found

    Cloning transformations in spin networks without external control

    Full text link
    In this paper we present an approach to quantum cloning with unmodulated spin networks. The cloner is realized by a proper design of the network and a choice of the coupling between the qubits. We show that in the case of phase covariant cloner the XY coupling gives the best results. In the 1->2 cloning we find that the value for the fidelity of the optimal cloner is achieved, and values comparable to the optimal ones in the general N->M case can be attained. If a suitable set of network symmetries are satisfied, the output fidelity of the clones does not depend on the specific choice of the graph. We show that spin network cloning is robust against the presence of static imperfections. Moreover, in the presence of noise, it outperforms the conventional approach. In this case the fidelity exceeds the corresponding value obtained by quantum gates even for a very small amount of noise. Furthermore we show how to use this method to clone qutrits and qudits. By means of the Heisenberg coupling it is also possible to implement the universal cloner although in this case the fidelity is 10% off that of the optimal cloner.Comment: 12 pages, 13 figures, published versio

    Transport properties of a periodically driven superconducting single electron transistor

    Full text link
    We discuss coherent transport of Cooper pairs through a Cooper pair shuttle. We analyze both the DC and AC Josephson effect in the two limiting cases where the charging energy ECE_C is either much larger or much smaller than the Josephson coupling EJE_J. In the limit EJâ‰ȘECE_J \ll E_C we present the detailed behavior of the critical current as a function of the damping rates and the dynamical phases. The AC effect in this regime is very sensitive to all dynamical scales present in the problem. The effect of fluctuations of the external periodic driving is discussed as well. In the opposite regime the system can be mapped onto the quantum kicked rotator, a classically chaotic system. We investigate the transport properties also in this regime showing that the underlying classical chaotic dynamics emerges as an incoherent transfer of Cooper pairs through the shuttle. For an appropriate choice of the parameters the Cooper pair shuttle can exhibit the phenomenon of dynamical localization. We discuss in details the properties of the localized regime as a function of the phase difference between the superconducting electrodes and the decoherence due to gate voltage fluctuations. Finally we point how dynamical localization is reflected in the noise properties of the shuttle.Comment: 22 pages, 7 figures; v3 (published version): added references, improved readabilit

    A behavioral comparison of male and female adults with high functioning autism spectrum conditions

    Get PDF
    Autism spectrum conditions (ASC) affect more males than females in the general population. However, within ASC it is unclear if there are phenotypic sex differences. Testing for similarities and differences between the sexes is important not only for clinical assessment but also has implications for theories of typical sex differences and of autism. Using cognitive and behavioral measures, we investigated similarities and differences between the sexes in age- and IQ-matched adults with ASC (high-functioning autism or Asperger syndrome). Of the 83 (45 males and 38 females) participants, 62 (33 males and 29 females) met Autism Diagnostic Interview-Revised (ADI-R) cut-off criteria for autism in childhood and were included in all subsequent analyses. The severity of childhood core autism symptoms did not differ between the sexes. Males and females also did not differ in self-reported empathy, systemizing, anxiety, depression, and obsessive-compulsive traits/symptoms or mentalizing performance. However, adult females with ASC showed more lifetime sensory symptoms (p = 0.036), fewer current socio-communication difficulties (p = 0.001), and more self-reported autistic traits (p = 0.012) than males. In addition, females with ASC who also had developmental language delay had lower current performance IQ than those without developmental language delay (p<0.001), a pattern not seen in males. The absence of typical sex differences in empathizing-systemizing profiles within the autism spectrum confirms a prediction from the extreme male brain theory. Behavioral sex differences within ASC may also reflect different developmental mechanisms between males and females with ASC. We discuss the importance of the superficially better socio-communication ability in adult females with ASC in terms of why females with ASC may more often go under-recognized, and receive their diagnosis later, than males

    Optical properties of atomic Mott insulators: from slow light to dynamical Casimir effects

    Full text link
    We theoretically study the optical properties of a gas of ultracold, coherently dressed three-level atoms in a Mott insulator phase of an optical lattice. The vacuum state, the band dispersion and the absorption spectrum of the polariton field can be controlled in real time by varying the amplitude and the frequency of the dressing beam. In the weak dressing regime, the system shows unique ultra-slow light propagation properties without absorption. In the presence of a fast time modulation of the dressing amplitude, we predict a significant emission of photon pairs by parametric amplification of the polaritonic zero-point fluctuations. Quantitative considerations on the experimental observability of such a dynamical Casimir effect are presented for the most promising atomic species and level schemes

    CALONECTRIS BOREALIS (AVES, PROCELLARIIDAE) COMO UN REGISTRO NUEVO PARA DOS ESPECIES DE NEMÁTODOS EN BRASIL

    Get PDF
    Contracaecum pelagicum Johnston & Mawson, 1942 y Seuratia shipleyi (Stossich, 1900) estån registrados en Brasil parasitando Calonectris borealis (Cory, 1881), que es un nuevo huésped para ambas especies. Se presentam las principales medidas de estas especies en el nuevo huésped

    LISTA DE CESTODA DO BRASIL

    Get PDF
    Se presenta una lista completa de las 432 especies de Cestoda que se han descrito y / o registrados en Brasil. Se distribuyen atravĂ©s de 15 Ăłrdenes y 36 familias; 50 especies no fueron identificadas y 9 se consideran species inquirenda. Entre los peces, Zungaro zungaro (Humboldt in Humboldt & Valenciennes, 1821) fue el hospedador que fue mĂĄs parasitadas (con 18 especies de cestodos); entre los anfibios, fue Rhinella icterica Spix, 1824, con 3 especies; y entre los reptiles, fue Bothrops jararaca (Wied-Neuwied, 1824), con 7 especies. Entre las aves, Gallus gallus (Linnaeus, 1758) presentĂł el mayor numero de asociaciones con cestodos, de tal manera que 13 especies se han registrado en Brasil y teniendo en cuenta los mamĂ­feros, Homo sapiens (Linnaeus, 1758) presentan 13 especies diferentes. Pocos representantes de estas especies de cestode se reportaran de invertebrados. El pequeño nĂșmero de los helmintos parĂĄsitos descritos es probablemente debido al submuestreo de hospedadores potenciales, junto con el pequeño nĂșmero de expertos en la taxonomĂ­a de los parĂĄsitos

    Electroweak Baryogenesis in Non-minimal Composite Higgs Models

    Full text link
    We address electroweak baryogenesis in the context of composite Higgs models, pointing out that modifications to the Higgs and top quark sectors can play an important role in generating the baryon asymmetry. Our main observation is that composite Higgs models that include a light, gauge singlet scalar in the spectrum [as in the model based on the symmetry breaking pattern SO(6)/SO(5)], provide all necessary ingredients for viable baryogenesis. In particular, the singlet leads to a strongly first-order electroweak phase transition and introduces new sources of CP violation in dimension-five operators involving the top quark. We discuss the amount of baryon asymmetry produced and the experimental constraints on the model.Comment: 15 pages, 7 figure

    Methodology for a Comprehensive Health Impact Assessment in Water Supply and Sanitation Programmes for Brazil

    Get PDF
    Based on the broader concept of health proposed by the Pan-American Health Organization/World Health Organization (PAHO/ WHO), 2018, and the absence in the literature of indices that translate the causal relationship between sanitation and health, a methodology for assessing the health impact of a water and sanitation programmes, known as a Health Impact Assessment (HIA), was developed, specifically in the Brazilian context, and focused on a school in the northeast of the country. Through exploratory and descriptive evidence, and using documentary research as a method, a retrospective survey was carried out from 2000 to 2022 using documents proposing evaluation methodologies. A single document was found to fit the research objective, which was used to develop the proposed HIA methodology. Development of the methodology consisted of two stages: definition of the health dimensions and selection of the indicators making up each dimension. The HIA methodology was then applied to a school in northeast Brazil to test its use, before a water-efficient management intervention was going to be used. The overall score of 46% indicated that there was room for improvement, which the new management approach could facilitate. This methodology is therefore proposed to be an instrument for the evaluation of public water and sanitation policies, thus assisting managers in the decision-making process and in guiding sanitation programs and plans
    • 

    corecore