Klein tunneling and Dirac potentials in trapped ions

We propose the quantum simulation of the Dirac equation with potentials, allowing the study of relativistic scaterring and the Klein tunneling. This quantum relativistic effect permits a positive-energy Dirac particle to propagate through a repulsive potential via the population transfer to negative-energy components. We show how to engineer scalar, pseudoscalar, and other potentials in the 1+1 Dirac equation by manipulating two trapped ions. The Dirac spinor is represented by the internal states of one ion, while its position and momentum are described by those of a collective motional mode. The second ion is used to build the desired potentials with high spatial resolution.Comment: 4 pages, 3 figures, minor change

Quantum simulation of the Klein paradox with trapped ions

We report on quantum simulations of relativistic scattering dynamics using trapped ions. The simulated state of a scattering particle is encoded in both the electronic and vibrational state of an ion, representing the discrete and continuous components of relativistic wave functions. Multiple laser fields and an auxiliary ion simulate the dynamics generated by the Dirac equation in the presence of a scattering potential. Measurement and reconstruction of the particle wave packet enables a frame-by-frame visualization of the scattering processes. By precisely engineering a range of external potentials we are able to simulate text book relativistic scattering experiments and study Klein tunneling in an analogue quantum simulator. We describe extensions to solve problems that are beyond current classical computing capabilities.Comment: 3 figures, accepted for publication in PR

Quantum Simulation of Quantum Field Theories in Trapped Ions

We propose the quantum simulation of a fermion and an antifermion field modes interacting via a bosonic field mode, and present a possible implementation with two trapped ions. This quantum platform allows for the scalable add-up of bosonic and fermionic modes, and represents an avenue towards quantum simulations of quantum field theories in perturbative and nonperturbative regimes.Comment: To be published in Physical Review Letter

Relativistic quantum mechanics with trapped ions

We consider the quantum simulation of relativistic quantum mechanics, as described by the Dirac equation and classical potentials, in trapped-ion systems. We concentrate on three problems of growing complexity. First, we study the bidimensional relativistic scattering of single Dirac particles by a linear potential. Furthermore, we explore the case of a Dirac particle in a magnetic field and its topological properties. Finally, we analyze the problem of two Dirac particles that are coupled by a controllable and confining potential. The latter interaction may be useful to study important phenomena as the confinement and asymptotic freedom of quarks.Comment: 17 pages, 4 figure

Helminth communities of the exotic introduced turtle, Trachemys scripta elegans in southwestern Spain: Transmission from native turtles

We report the prevalence and diversity of helminth parasites found in native turtles Mauremys leprosa and Emys orbicularis from three localities in southwestern Spain and we describe the helminth communities of exotic turtles Trachemys scripta elegans coexisting in the wild with both native turtle species. Five nematodes species were identified, of which Serpinema microcephalus was the only species common between two localities, although infection parameters were different between them. This is the first report of cross transmission of S. microcephalus and Falcaustra donanaensis from native to exotic turtles and the first report of genus Physaloptera in turtles of the Palearctic Region. Continuous releasing of exotic pet turtles in wildlife ecosystems increases the risk of parasite introductions and, consequently, potential transmission to native species, and highlights the impending need for regulation of pet turtle trade in Europe

Population genomics in Rhamdia quelen (Heptapteridae, Siluriformes) reveals deep divergence and adaptation in the Neotropical region

Rhamdia quelen, a Neotropical fish with hybridization between highly divergent mitochondrial DNA (mtDNA) lineages, represents an interesting evolutionary model. Previous studies suggested that there might be demographic differences between coastal lagoons and riverine environments, as well as divergent populations that could be reproductively isolated. Here, we investigated the genetic diversity pattern of this taxon in the Southern Neotropical Basin system that includes the La Plata Basin, Patos-Merin lagoon basin and the coastal lagoons draining to the SW Atlantic Ocean, through a population genomics approach using 2b-RAD-sequencing-derived single nucleotide polymorphisms (SNPs). The genomic scan identified selection footprints associated with divergence and suggested local adaptation environmental drivers. Two major genomic clusters latitudinally distributed in the Northern and Southern basins were identified, along with consistent signatures of divergent selection between them. Population structure based on the whole set of loci and on the presumptive neutral vs. adaptive loci showed deep genomic divergence between the two major clusters. Annotation of the most consistent SNPs under divergent selection revealed some interesting candidate genes for further functional studies. Moreover, signals of adaptation to a coastal lagoon environment mediated by purifying selection were found. These new insights provide a better understanding of the complex evolutionary history of R. quelen in the southernmost basin of the Neotropical regio

Agreement between a simple dyspnea-guided treatment algorithm for stable COPD and the GOLD guidelines: A pilot study

Introduction: Guidelines recommendations for the treatment of COPD are poorly followed. This could be related to the complexity of classification and treatment algorithms. The purpose of this study was to validate a simpler dyspnea-based treatment algorithm for inhaled pharmacotherapy in stable COPD, comparing its concordance with the current Global Initiative for Obstructive Lung Disease (GOLD) guideline. Methods: We enrolled patients who had been diagnosed with COPD in three primary care facilities and two tertiary hospitals in Spain. We determined anthropometric data, forced expiratory volume in the 1st second (percent), exacerbations, and dyspnea based on the modified Medical Research Council scale. We evaluated the new algorithm based on dyspnea and exacerbations and calculated the concordance with the current GOLD recommendations. Results: We enrolled 100 patients in primary care and 150 attending specialized care in a respiratory clinic. There were differences in the sample distribution between cohorts with 41% vs 26% in grade A, 16% vs 12% in grade B, 16% vs 22% in grade C, and 27% vs 40% in grade D for primary and respiratory care, respectively (P=0.005). The coincidence of the algorithm with the GOLD recommendations in primary care was 93% and 91.8% in the respiratory care cohort. Conclusion: A simple dyspnea-based treatment algorithm for inhaled pharmacotherapy of COPD could be useful in the management of COPD patients and concurs very well with the recommended schema suggested by the GOLD initiative