Universal decoherence induced by an environmental quantum phase transition

Decoherence induced by coupling a system with an environment may display universal features. Here we demostrate that when the coupling to the system drives a quantum phase transition in the environment, the temporal decay of quantum coherences in the system is Gaussian with a width independent of the system-environment coupling strength. The existence of this effect opens the way for a new type of quantum simulation algorithm, where a single qubit is used to detect a quantum phase transition. We discuss possible implementations of such algorithm and we relate our results to available data on universal decoherence in NMR echo experiments

Some applications of the quantum cell model

Ph.D.Harold A. Gersc

A Focal Plane Array and Electronics Model for CMOS and CCD Sensors in the AFIT Sensor and Scene Emulation Tool (ASSET)

Electro-optical and infrared (EO/IR) sensor models are useful tools that can facilitate understanding a system\u27s behavior without expensive and time-consuming testing of an actual system. EO/IR models are especially important to the military industry where truth data is required but is sometimes impractical to obtain through experimentation due to expense or difficulties in procuring hardware. This work describes implementation of a focal plane array (FPA) model of charge-coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) photodetectors as a component in the Air Force Institute of Technology (AFIT) Sensor and Scene Emulation Tool (ASSET). The FPA model covers conversion of photo-generated electrons to voltage and then to digital numbers. It incorporates sense node, source follower, and analog-to-digital converter (ADC) components contributing to gain non-linearities and includes noise sources associated with the detector and electronics such as shot, thermal, 1/f, and quantization noise. This thesis describes the higher fidelity FPA and electronics model recently incorporated into ASSET, and it also details validation of the improved model using EO/IR imager data collected with laboratory measurements. The result is an improved model capable of generating realistic synthetic data representative of a wide range of systems for use in new algorithm development and data exploitation techniques supporting a broad community of academic, commercial, and military researchers

Memoria del segundo congreso internacional sobre paz, democracia y desarrollo

El presente texto analiza algunos de los principales acontecimientos políticos en Venezuela ocurridos entre 2004, cuando se produjeron transformaciones importantes en la institución superior del poder judicial, y 2007, año que se cierra con la celebración de un referéndum que pretendía introducir cambios constitucionales de gran significación. Sin embargo, el apego a esta delimitación temporal no es totalmente estricto, pues en ocasiones, para contextualizar lo sucedido en el periodo estudiado, se maneja información anterior a 2004 y, para mostrar sus consecuencias, se incluyen datos relativos a los primeros meses de 2008. Este estudio se basa sobre todo en información periodística; en especial se rastreó sistemáticamente la proporcionada por el semanario Informe Latinoamericano, editado por una de las actualmente más relevantes empresas de información sobre América Latina, Latin American Newsletters, por lo que no ha sido necesario emplear un aparato crítico convencional