SPARQL Playground: A block programming tool to experiment with SPARQL

SPARQL is a powerful query language for SemanticWeb data sources but one which is quite complex to master. As the block programming paradigm has been succesfully used to teach programming skills, we propose a tool that allows users to build and run SPARQL queries on an endpoint without previous knowledge of the syntax of SPARQL and the model of the data in the endpoint (vocabularies and semantics). This user interface attempts to close the gap between tools for the lay user that do not allow to express complex queries and overtly complex technical tools

A Deterministic and Nondestructively-Verifiable Photon Number Source

We present a deterministic approach based on continuous measurement and real-time quantum feedback control to prepare arbitrary photon number states of a cavity mode. The procedure passively monitors the number state actually achieved in each feedback stabilized measurement trajectory, thus providing a nondestructively verifiable photon source. The feasibility of a possible cavity QED implementation in the many-atom good-cavity coupling regime is analyzed

Collective Uncertainty in Partially-Polarized and Partially-Decohered Spin-1/2 Systems

It has become common practice to model large spin ensembles as an effective pseudospin with total angular momentum J = N x j, where j is the spin per particle. Such approaches (at least implicitly) restrict the quantum state of the ensemble to the so-called symmetric Hilbert space. Here, we argue that symmetric states are not generally well-preserved under the type of decoherence typical of experiments involving large clouds of atoms or ions. In particular, symmetric states are rapidly degraded under models of decoherence that act identically but locally on the different members of the ensemble. Using an approach [Phys. Rev. A 78, 052101 (2008)] that is not limited to the symmetric Hilbert space, we explore potential pitfalls in the design and interpretation of experiments on spin-squeezing and collective atomic phenomena when the properties of the symmetric states are extended to systems where they do not apply.Comment: 13 pages, 7 figure

La necesidad de un enfoque etnográfico en Perú

Un desplazamiento de personas rara vez se explica únicamente por factores ambientales o climáticos. Por lo tanto, un análisis que no tenga en cuenta las consecuencias culturales del cambio climático para las sociedades afectadas estará incompleto