853 research outputs found
Cloning transformations in spin networks without external control
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
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 is either much larger or much smaller than the
Josephson coupling . In the limit 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
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 (pâ=â0.036), fewer current socio-communication difficulties (pâ=â0.001), and more self-reported autistic traits (pâ=â0.012) 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
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 NEMĂTODOS EN BRASIL
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
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
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
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
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