Resonance trapping and saturation of decay widths

Resonance trapping appears in open many-particle quantum systems at high level density when the coupling to the continuum of decay channels reaches a critical strength. Here a reorganization of the system takes place and a separation of different time scales appears. We investigate it under the influence of additional weakly coupled channels as well as by taking into account the real part of the coupling term between system and continuum. We observe a saturation of the mean width of the trapped states. Also the decay rates saturate as a function of the coupling strength. The mechanism of the saturation is studied in detail. In any case, the critical region of reorganization is enlarged. When the transmission coefficients for the different channels are different, the width distribution is broadened as compared to a chi_K^2 distribution where K is the number of channels. Resonance trapping takes place before the broad state overlaps regions beyond the extension of the spectrum of the closed system.Comment: 18 pages, 8 figures, accepted by Phys. Rev.

Dynamics of quantum systems

A relation between the eigenvalues of an effective Hamilton operator and the poles of the $S$ matrix is derived which holds for isolated as well as for overlapping resonance states. The system may be a many-particle quantum system with two-body forces between the constituents or it may be a quantum billiard without any two-body forces. Avoided crossings of discrete states as well as of resonance states are traced back to the existence of branch points in the complex plane. Under certain conditions, these branch points appear as double poles of the $S$ matrix. They influence the dynamics of open as well as of closed quantum systems. The dynamics of the two-level system is studied in detail analytically as well as numerically.Comment: 21 pages 7 figure

Phase transitions in open quantum systems

We consider the behaviour of open quantum systems in dependence on the coupling to one decay channel by introducing the coupling parameter $\alpha$ being proportional to the average degree of overlapping. Under critical conditions, a reorganization of the spectrum takes place which creates a bifurcation of the time scales with respect to the lifetimes of the resonance states. We derive analytically the conditions under which the reorganization process can be understood as a second-order phase transition and illustrate our results by numerical investigations. The conditions are fulfilled e.g. for a picket fence with equal coupling of the states to the continuum. Energy dependencies within the system are included. We consider also the generic case of an unfolded Gaussian Orthogonal Ensemble. In all these cases, the reorganization of the spectrum occurs at the critical value $\alpha_{crit}$ of the control parameter globally over the whole energy range of the spectrum. All states act cooperatively.Comment: 28 pages, 22 Postscript figure

Observation of resonance trapping in an open microwave cavity

The coupling of a quantum mechanical system to open decay channels has been theoretically studied in numerous works, mainly in the context of nuclear physics but also in atomic, molecular and mesoscopic physics. Theory predicts that with increasing coupling strength to the channels the resonance widths of all states should first increase but finally decrease again for most of the states. In this letter, the first direct experimental verification of this effect, known as resonance trapping, is presented. In the experiment a microwave Sinai cavity with an attached waveguide with variable slit width was used.Comment: to be published in Phys. Rev. Let

An evaluation of the prevalence of vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) in hospital food

Los artículos que componen este libro ilustran desde múltiples puntos de vista el concepto de patrimonio biocultural. El contenido de la publicación se estructura en tres espacios sintetizados en las problemáticas asociadas al patrimonio biológico y cultural, el territorio y las disputas territoriales, la construcción identitaria y los problema de carácter socio-históricos de las comunidades afro indoamericanas. Ello permite, por un lado, obtener una aproximación contrastante, holística y compleja de la realidad latinoamericana y por otra lado sumar aportes a un concepto en construcción que no esconde su intencionalidad emancipadora.Agradecimientos; Introducción; PATRIMONIO BIOCULTURAL: Juan Pohlenz Córdova / La disputa por el patrimonio biocultural. Un acercamiento desde Mesoamérica; León Enrique Ávila Romero / La disputa por el patrimonio biocultural, la economía verde y sus impactos en los pueblos indígenas; Bernardo Javier Tobar / Lugares de vida y registros de la memoria biocultural en el Pacífico sur-colombiano; Iskra García Vázquez, Rocío Becerra Montané y Gimena Pérez Ortega / Uso, aprovechamiento social y conservación de las plantas medicinales en México; Kelly Giovanna Muñoz Balcázar / Transformaciones del territorio y el patrimonio biocultural a partir del proceso de industrialización. Recuperación de la finca tradicional en el municipio de Corinto, vereda La Paila; TERRITORIO: Johnny L. Ledezma Rivera / Reflexiones sobre las concepciones y visiones de lo que se entiende por territorio; Sindy Hernández Bonilla / ¿Justicia o legalidad para los q’eqchi’es? Agustín Ávila Romero / Turismo y pueblos indígenas de México: despojo y veredas de apropiación comunitaria; SOCIEDADES AFROINDOAMERICANAS EN MOVIMIENTO Johnny L. Ledezma Rivera / Construcción e implementación de las autonomías indígenas en Bolivia: avances y retrocesos; Stefano Claudio Sartorello / Educar para el arraigo sociocultural. El perfil de egreso de alumn@s indígenas en una propuesta educativa intercultural y bilingüe en Chiapas; Elena Pareja y Virginia Cornalino / La cultura afrodescendiente en la constitución del Estado-nación (1870-1900). La reconstrucción de los mapas de identidad en la frontera uruguayo-brasileña; Karla Chagas y Natalia Stalla / Mano de obra negra en el Estado Oriental: una mirada del trabajo esclavo y libre a través del análisis de casos; Diego E. Piñeiro y Joaquín Cardeillac / Los afro-descendientes en el campo uruguayo; Soledad Figueredo y Matías Carámbula Pareja / Puntos en el mapa: ensayo sobre identidad, inmovilidad y cultura de la población afrodescendiente en el medio rural uruguayo

Parallel implementation of a cellular automaton model for the simulation of laser dynamics

A parallel implementation for distributed-memory MIMD systems of a 2D discrete model of laser dynamics based on cellular au- tomata is presented. The model has been implemented on a PC cluster using a message passing library. A good performance has been obtained, allowing us to run realistic simulations of laser systems in clusters of workstations, which could not be a orded on an individual machine due to the extensive runtime and memory size needed.Ministerio de Educación y Ciencia TIN2005-08818-C04-0