267 research outputs found
Effective Quantum Dynamics of Interacting Systems with Inhomogeneous Coupling
We study the quantum dynamics of a single mode/particle interacting
inhomogeneously with a large number of particles and introduce an effective
approach to find the accessible Hilbert space where the dynamics takes place.
Two relevant examples are given: the inhomogeneous Tavis-Cummings model (e.g.,
N atomic qubits coupled to a single cavity mode, or to a motional mode in
trapped ions) and the inhomogeneous coupling of an electron spin to N nuclear
spins in a quantum dot.Comment: 9 pages and 10 figures, new version, accepted in Physical Review
Salmonella enterica: a review or the trilogy agent, host and environment and its importance in Chile
Indexación: Web of Science; Scopus; Scielo.Salmonella enterica es uno de los principales patógenos transmitidos por los alimentos en el mundo, siendo la primera causa de brotes de intoxicación alimentaria en Chile. A pesar de todos los esfuerzos de control y prevención desplegados, la incidencia en las personas se ha mantenido alta, por lo que diversos factores podrían estar influenciando el comportamiento epidemiológico de esta infección. El objetivo de esta revisión es describir factores referidos tanto al agente biológico, al hospedero humano y al medio ambiente, que podrían tener mayor trascendencia en Chile. De esta forma, se infieren ámbitos prioritarios para la investigación de S. enterica, que permitan entender su dispersión en la naturaleza y su éxito como patógeno de un amplio rango de hospederos. A futuro, el mayor conocimiento de estos determinantes facilitará la implementación de estrategias de bioseguridad y vigilancia para la prevención de la enfermedad en las personas y en los animales.Salmonella enterica is a major foodborne pathogen worldwide, being the main cause of outbreaks by food consumption in Chile. Despite all efforts deployed for control and prevention, the high incidence in people still persists, with several factors that could be influencing the epidemiological behavior of this infection. The objective of this review is to identify these factors belonging to the biological agent, the human host and the environment, which probably have a greater importance in Chile. Thus, priority areas for research of S. enterica are inferred, which hopefully will help to understand its spread in nature and its success as a wide host range pathogen. In the future, increased understanding of these determinants will facilitate the implementation of biosecurity and surveillance strategies for the prevention of disease in people and animals.http://ref.scielo.org/kz75k
Failures of Quay Walls During Chilean Earthquake of March 1985
Extensive damage took place in the quay walls in the Ports of Valparaíso and San Antonio during the Chilean earthquake of March 1985. Different types of retaining structures such as gravity retaining walls built with concrete blocks, sheetpiles and decks on vertical piles were subjected to large shaking ranging from 0.3 - 0.45g at Valparaíso Port to more than 0.6g at San Antonio. Some of the retaining structures collapsed and others behave quite well. In addition, some liquefaction and settlements in the sandy fill below the yards did occur at San Antonio, along with permanent displacements in the fill slope behind some of the decks supported by piles. The behavior of 7 berths at Valparaíso and 7 berths at San Antonio is discussed taking into account soil characteristics and field measurements performed after the earthquake
Single observable concurrence measurement without simultaneous copies
We present a protocol that allows us to obtain the concurrence of any two
qubit pure state by performing a minimal and optimal tomography of one of the
subsystems through measuring a single observable of an ancillary four
dimensional qudit. An implementation for a system of trapped ions is also
proposed, which can be achieved with present day experimental techniques.Comment: 4 pages, 1 figur
Magnetic behavior of nanoparticles in patterned thin films
The magnetic behavior of truncated conical nanoparticles in patterned thin
films is investigated as a function of their size and shape. Using a scaling
technique, phase diagrams giving the relative stability of characteristic
internal magnetic structures of the particles are obtained. The role of the
uniaxial anisotropy in determining the magnetic properties of such systems is
discussed, and a simple method for stablishing its strength is proposed.Comment: 4 pages, 4 figure
Quantum simulation of entanglement dynamics in a quantum processor
We implement a five-qubit protocol in IBM quantum processors to get
entanglement dynamics in a two qubit system in the presence of an environment.
Specifically, two qubits represent the main system, another two qubits the
environment, and an additional qubit is used as an auxiliary qubit to perform
the quantum entanglement estimation. We focus on measuring, in this
superconducting quantum processor, the sudden death and sudden birth of
entanglement. We obtain the quantum entanglement evolution of the main system
qubits and the environment qubits as the average of independent
experiments in the same quantum device, observing that the noisy nature of
current quantum processors produce a shift on times signaling sudden death o
sudden birth of entanglement. This work takes relevance showing the usefulness
of current noisy quantum devices to test fundamental concepts in quantum
information.Comment: 6 pages, and 12 figure
Diabetes y su impacto en el territorio periodontal
ResumenDiabetes y enfermedad periodontal corresponden probablemente al mejor ejemplo de cómo una enfermedad sistémica puede tener un efecto en el territorio periodontal. Si bien esta asociación ha sido extensamente estudiada, muchas de las asociaciones propuestas presentan contradicciones. En la presente revisión de la literatura se analizan los siguientes tópicos relevantes para la práctica clínica en periodoncia e implantología: i) Identificación de enfermedad periodontal severa y su capacidad para diagnosticar casos de diabetes; ii) Efectos de la diabetes sobre la enfermedad periodontal; iii) Efectos de la diabetes sobre la reparación periodontal y periimplantaria; iv) Efecto del tratamiento periodontal sobre el control metabólico de la diabetes.AbstractDiabetes and periodontal disease correspond to conditions that probably exemplify how a systemic disease may have a strong impact in the periodontium. Although this association has been studied for several years, many of these studies still show contradictory results. The present review analyses the following questions relevant for the clinician in the fields of periodontology: i) Value of the diagnosis of severe periodontitis and its capacity to identify previously un-diagnosed cases of diabetes; ii) Effects of diabetes on periodontal disease; iii) Effects of diabetes on periodontal and periimplant tissue repair and regeneration and; iv) Effect of periodontal therapy on the metabolic control of diabetes
Calculation of quantum discord for qubit-qudit or N qubits
Quantum discord, a kind of quantum correlation, is defined as the difference
between quantum mutual information and classical correlation in a bipartite
system. It has been discussed so far for small systems with only a few
independent parameters. We extend here to a much broader class of states when
the second party is of arbitrary dimension d, so long as the first, measured,
party is a qubit. We present two formulae to calculate quantum discord, the
first relating to the original entropic definition and the second to a recently
proposed geometric distance measure which leads to an analytical formulation.
The tracing over the qubit in the entropic calculation is reduced to a very
simple prescription. And, when the d-dimensional system is a so-called X state,
the density matrix having non-zero elements only along the diagonal and
anti-diagonal so as to appear visually like the letter X, the entropic
calculation can be carried out analytically. Such states of the full bipartite
qubit-qudit system may be named "extended X states", whose density matrix is
built of four block matrices, each visually appearing as an X. The optimization
involved in the entropic calculation is generally over two parameters, reducing
to one for many cases, and avoided altogether for an overwhelmingly large set
of density matrices as our numerical investigations demonstrate. Our results
also apply to states of a N-qubit system, where "extended X states" consist of
(2^(N+2) - 1) states, larger in number than the (2^(N+1) - 1) of X states of N
qubits. While these are still smaller than the total number (2^(2N) - 1) of
states of N qubits, the number of parameters involved is nevertheless large. In
the case of N = 2, they encompass the entire 15-dimensional parameter space,
that is, the extended X states for N = 2 represent the full qubit-qubit system.Comment: 6 pages, 1 figur
Dark States and Interferences in Cascade Transitions of Ultra-Cold Atoms in a Cavity
We examine the competition among one- and two-photon processes in an
ultra-cold, three-level atom undergoing cascade transitions as a result of its
interaction with a bimodal cavity. We show parameter domains where two-photon
transitions are dominant and also study the effect of two-photon emission on
the mazer action in the cavity. The two-photon emission leads to the loss of
detailed balance and therefore we obtain the photon statistics of the cavity
field by the numerical integration of the master equation. The photon
distribution in each cavity mode exhibits sub- and super- Poissonian behaviors
depending on the strength of atom-field coupling. The photon distribution
becomes identical to a Poisson distribution when the atom-field coupling
strengths of the modes are equal.Comment: 15 pages including 7 figures in Revtex, submitted to PR
- …