Nonclassicality of states and measurements by breaking classical bounds on statistics

Original article can be found at: http://pra.aps.org/ Copyright American Physical Society. DOI: 10.1103/PhysRevA.79.042105We derive exceedingly simple practical procedures revealing the quantum nature of states and measurements by the violation of classical upper bounds on the statistics of arbitrary measurements. Data analysis is minimum, and definite conclusions are obtained without evaluation of moments or any other more sophisticated procedures. These nonclassical tests are independent of other typical quantum signatures such as sub-Poissonian statistics, quadrature squeezing, or oscillatory statistics. This approach can be equally well applied to very diverse situations such as single- and two-mode fields, observables with continuous and discrete spectra, finite- and infinite-dimensional systems, and ideal and noisy measurements.Peer reviewe

SU(2)-invariant depolarization of quantum states of light

We develop an SU(2)-invariant approach to the depolarization of quantum systems as the effect of random unitary SU(2) transformations. From it we derive an SU(2)-invariant Markovian master equation. This is applied to several quantum states examining whether nonclassical states are more sensible to depolarization than the classical ones. Furthermore, we show that this depolarization model provides a nontrivial generalization of depolarization channels to states of arbitrary dimension.Comment: RevTex4 file, color figures, published versio

Nonlinear Michelson interferometer for improved quantum metrology

We examine quantum detection via a Michelson interferometer embedded in a gas with Kerr nonlinearity. This nonlinear interferometer is illuminated by pulses of classical light. This strategy combines the robustness against practical imperfections of classical light with the improvement provided by nonlinear processes. Regarding ultimate quantum limits, we stress that, as a difference with linear schemes, the nonlinearity introduces pulse duration as a new variable into play along with the energy resources.Comment: 5 pages, 1 figure. Close to published versio

Nonlinear fiber gyroscope for quantum metrology

We examine the performance of a nonlinear fiber gyroscope for improved signal detection beating the quantum limits of its linear counterparts. The performance is examined when the nonlinear gyroscope is illuminated by practical field states, such as coherent and quadrature squeezed states. This is compared with the case of more ideal probes such as photon-number states.Comment: 8 pages, 1 figur

Visions of a modern-day road structure: Granada’s Camino de Ronda

Peer Reviewe

On the Role of Relative Prices and Capital Flows in Balance-of-Payments Constrained Growth: the Experiences of Portugal and Spain in the Euro Area

Broadly speaking, the balance-of-payments constraint hypothesis as developed by Thirlwall has been empirically supported. Yet, it shows some shortcomings highlighted in the literature. In our opinion, two of them must be analysed. First, temporary disequilibria and capital flows must be incorporated into the balance-of-payments constrained growth models. Second, the role of relative prices must be made explicit, since it can be relevant even in an external constraint framework. This study is aimed at developing a model that incorporates both possibilities: temporary external disequilibria and a the impact of relative prices. This model is subsequently used to analyse the evolution of the Spanish and Portuguese economies in last decades, and, in particular, the different path shown by both countries since their accession to the Eurozone.Pese al respaldo empírico con el que ha contado la teoría de la restricción externa desarrollada a partir del modelo de Thirlwall, éste muestra algunas deficiencias destacadas en la literatura. En nuestra opinión, dos de ellas merecen ser analizadas. Por un lado, la necesidad de incorporar desequilibrios transitorios de la balanza de pagos y los consiguientes flujos de capital. Por otro, creemos los precios relativos pueden desempeñar un papel importante en el comercio exterior, sin que ello invalide la existencia de una restricción externa. El objetivo del presente trabajo consiste en desarrollar un modelo que incorpore ambas cuestiones, permitiendo, así, un mayor protagonismo a los precios relativos y a los desequilibrios temporales de la balanza de pagos. Este modelo se emplea posteriormente para analizar la evolución de las economías española y portuguesa en las últimas décadas y, en especial, las diferencias mostradas desde su incorporación a la Eurozona.Growth, Balance of payments constraint, Exchange rate.

Eight New Species of Poechiliid Fishes of the Genus Limia from Hispaniola

Pending revision of the genus, eight new species of Limia are described to make the names available. The genus Is divided into two subgenera, one of which, Odontollmia, is proposed as new. The two subgenera are characterized and the number of species In Odontollmia is six and in Limia 13

ACADEMIC CULTURAL GUIDES: SPONSORS OF ACADEMIC LITERACY DEVELOPMENT

This dissertation explores Hispanic/Latino students’ perceptions about language association and identity, the institution, and white professors at a small Midwestern liberal arts college. Issues addressed include the origin of a stigmatized relationship between Euro-Americans and Hispanics in the U.S. and its spill into academia, negative perceptions that affect students’ performance and persistence in the university, discussing the culture of power of the institution with students as a form of sponsorship, and providing academic literacy sponsorship through an Academic Cultural Guide role. The dissertation concludes with examples of strategies I have used in the first-year writing classroom to establish transparency of my role as instructor, teach literacy narratives, and foster relationships with students to meet their academic needs

Character Displacement and Coexistence in Two Poeciliid Fishes of the Genus Poecilia (Mollienesia) from Hispaniola

Character displacement in animals, particularly in fishes, is reviewed and the new approach of Grant (1975) is used in this study to demonstrate character displacement in P. hispaniolana and P. dominicensis, two closely related and partly sympatric species of mollies endemic to Hispaniola. Background information is given on the probable origin, evolution, attainment of present partial sympatry and length of coexistence of the two species, as indicated by their present distribution and the paleogeography of Hispaniola. It is hypothesized that a common ancestor to both species existed on the island prior to the Miocene about 20 million years ago. It is also hypothesized that the ancestral population was split during the Miocene-Pliocene for a period of about 18 million years, that the two species evolved during that time, and that the barrier to their dispersal was eliminated in late Pliocene about two million years ago. It is assumed that during that last period the present distribution and partial sympatry were attained, and that the two species have coexisted twice as long in the localities where character displacement shows greater magnitude. Analyses of meristics, morphometries, and reproduction are given to demonstrate character displacement in fin ray, scale, and gill-raker number, and in body size and fecundity. Divergent, convergent, and parallel displacement were found to occur as well as a change of reproductive strategy for P. dominicensis in sympatry. Causes and effects of displacement in the two species are discussed and later summarized in combination with tentative conclusions

A New Species of Poeciliid Fish of the Genus Poecilia from Hispaniola, with Reinstatement and Redescription of P. dominicensis (Evermann and Clark)

Exploration of the streams and lakes of Hispaniola and available collections of poeciliid fishes from that island are discussed, followed by the taxonomic history and generic status of the two species described. The genera Limia and Mollienesia were synonymized with Poecilia by Rosen and Bailey (1963) and the former Mollienesia dominicensis of Evermann and Clark (1906) became a junior homonym of Limia dominicensis of Valenciennes (1846). Rosen and Bailey, therefore, renamed M. dominicensis of Evermann and Clark as Poecilia montana. Because Mollienesia is herein retained as a synonym of Poecilia but Limia is reinstated as a valid genus, Poecilia dominicensis of Evermann and Clark is no longer a junior homonym of Limia dominicensis of Valenciennes. The name montana, therefore, becomes a junior objective synonym of Evermann and Clark\u27s dominicensis. The new species herein described, although available to previous authors, had been hitherto confused with Poecilia dominicensis of Evermann and Clark. Both species are superficially similar but clearly distinct and more closely related to each other than either is to any of the other species of Poecilia. They are restricted to the island of Hispaniola and show character displacement in the several localities where they occur together