Browsing by Autor "Luis Quiroga"

Now showing 1 - 5 of 5

Dinámica de redes en dos dimensiones: Red tipo grafito
(LA Referencia, 1992) Jairo Arbey Rodríguez Mártinez; Rainer Paris; Carolina Camargo Lombana; Luis Quiroga
Se determinaron las propiedades básicas de las vibraciones reticulares en una red hexagonal (tipo grafito) a partir de la matriz dinámica que exhibe plenamente las simetrías del sistema. En la aproximación armónica y considerando interacciones hasta primeros vecinos, se obtuvieron dos parámetros independientes: Uno describe efectos de fuerzas centrales y el otro, efectos de fuerzas no centrales. Las relaciones de dispersión, obtenidas analíticamente, se muestran en diagramas tridimensionales para la primera zona de Brillouin, y a lo largo de líneas de alta simetría. Pedagógicamente se aporta un caso realista y no trivial para el estudio de fonones a nivel introductorio.
Electronic Structure of (001) Semiconducting MTe Surfaces (M = Zn, Cd, Hg)
(Wiley, 1990) F. J. Rodríguez; A. Camacho; Luis Quiroga; R. Baquero
Abstract By using the tight‐binding scheme with ten orbitals per atom (SP 3 S* and two spin orientations) the electronic projected bulk band structure, surface band structure (both anion‐and cation‐terminated surfaces), and the wave‐vector‐resolved density of states for these II‐VI semiconductors are calculated. A quickly convergent iterative technique is employed for calculating the Green function of the actual semi‐infinite crystal. This calculational method allows to precise very accurately, the energy of localized surface states. All the materials considered in this work present surface states with energies lying in the fundamental gap as well as surface states in the lenses opened in the projected bulk valence‐band continum. The atomic weight of each surface state is determined. The states in the fundamental gap turn out to be ‘bridge‐bond’‐type states for anion‐terminated surfaces and ‘dangling‐bond’‐type states for cation‐terminated surfaces.
Energy Conversion in Purple Bacteria Photosynthesis
(2012) Felipe Caycedo‐Soler; F. J. Rodríguez; Luis Quiroga; Guannan Zhao; Neil F. Johnson
The study of how photosynthetic organisms convert light offers insight not only into nature's evolutionary process, but may also give clues as to how best to design and manipulate artificial photosynthetic systems -- and also how far we can drive natural photosynthetic systems beyond normal operating conditions, so that they can harvest energy for us under otherwise extreme conditions. In addition to its interest from a basic scientific perspective, therefore, the goal to develop a deep quantitative understanding of photosynthesis offers the potential payoff of enhancing our current arsenal of alternative energy sources for the future. In the following Chapter, we consider the trade-off between dynamics, structure and function of light harvesting membranes in Rps. Photometricum purple bacteria, as a model to highlight the priorities that arise when photosynthetic organisms adapt to deal with the ever-changing natural environment conditions.
Planar Three-Body Problem with Calogero Interactions and a Magnetic Field
(Springer Science+Business Media, 1996) Augusto González; Luis Quiroga; Boris A. Rodríguez
Quantum information processing in semiconductor nanostructures
(Cornell University, 2000) John H. Reina; Luis Quiroga; Neil F. Johnson
A major question for condensed matter physics is whether a solid-state quantum computer can ever be built. Here we discuss two different schemes for quantum information processing using semiconductor nanostructures. First, we show how optically driven coupled quantum dots can be used to prepare maximally entangled Bell and Greenberger-Horne-Zeilinger states by varying the strength and duration of selective light pulses. The setup allows us to perform an all-optical generation of the quantum teleportation of an excitonic state in an array of coupled quantum dots. Second, we give a proposal for reliable implementation of quantum logic gates and long decoherence times in a quantum dots system based on nuclear magnetic resonance (NMR), where the nuclear resonance is controlled by the ground state transitions of few-electron QDs in an external magnetic field. The dynamical evolution of these systems in the presence of environmentally-induced decoherence effects is also discussed.