Doublon lifetimes in dissipative environments

We study the dissipative decay of states with a doubly occupied site in a two-electron Hubbard model, known as doublons. For the environment we consider charge and current noise which are modelled as a bosonic heat bath that couples to the onsite energies and the tunnel couplings, respectively. It turns out that the dissipative decay depends qualitatively on the type of environment as for charge noise, the life time grows with the electron-electron interaction. For current noise, by contrast, doublons become increasingly unstable with larger interaction. Numerical studies within a Bloch-Redfield approach are complemented by analytical estimates for the decay rates. For typical quantum dot parameters, we predict that the doublon life times up to 50 ns

Unconventional quantum optics in topological waveguide QED

The discovery of topological materials has challenged our understanding of condensed matter physics and led to novel and unusual phenomena. This has motivated recent developments to export topological concepts into photonics to make light behave in exotic ways. Here, we predict several unconventional quantum optical phenomena that occur when quantum emitters interact with a topological waveguide QED bath, namely, the photonic analogue of the Su-Schrieffer-Hegger model. When the emitters frequency lies within the topological band-gap, a chiral bound state emerges, which is located at just one side (right or left) of the emitter. In the presence of several emitters, it mediates topological, long-range tunable interactions between them, that can give rise to exotic phases such as double N\'eel ordered states. On the contrary, when the emitters' optical transition is resonant with the bands, we find unconventional scattering properties and different super/subradiant states depending on the band topology. We also investigate the case of a bath with open boundary conditions to understand the role of topological edge states. Finally, we propose several implementations where these phenomena can be observed with state-of-the-art technology.Comment: 17 pages, 10 figure

El conocimiento de las poblaciones del pasado a través de los restos óseos: Estudio antropológico de los restos óseos recuperados del yacimiento de Humanejos (Parla, Madrid)

Trabajo fin de grado en Biología Evolutiva y BiodiversidadEn este trabajo se presentan los resultados del estudio antropológico del yacimiento de Humanejos (segunda mitad s.IV – s.XVI) de Parla (Madrid). Se han analizado las diferentes variables biológicas (edad, sexo, talla, características de interés patológico y no patológico) y arqueológicas (posición, orientación, tipo de estructura, etc.) para tratar de aproximarse al conocimiento de la población arqueológica. Este estudio ha proporcionado un número mínimo de 154 individuos totales, donde predominan los adultos. Finalmente, se ha observado una cierta relación entre variables arqueológicas, pero no entre éstas y las variables biológica

Current self-oscillations, spikes and crossover between charge monopole and dipole waves in semiconductor superlattices

Self-sustained current oscillations in weakly-coupled superlattices are studied by means of a self-consistent microscopic model of sequential tunneling including boundary conditions naturally. Well-to-well hopping and recycling of charge monopole domain walls produce current spikes (high frequency modulation) superimposed on the oscillation. For highly doped injecting contacts, the self-oscillations are due to dynamics of monopoles. As the contact doping decreases, a lower-frequency oscillatory mode due to recycling and motion of charge dipoles is predicted. For low contact doping, this mode dominates and monopole oscillations disappear. At intermediate doping, both oscillation modes coexist as stable solutions and hysteresis between them is possible.Comment: 4 pages, 4 figure

Microscopic Model for Sequential Tunneling in Semiconductor Multiple Quantum Wells

We propose a selfconsistent microscopic model of vertical sequential tunneling through a multi-quantum well.The model includes a detailed description of the contacts,uses the Transfer Hamiltonian for expressions of the current and it treats the Coulomb interaction within a mean field approximation. We analyze the current density through a double well and a superlattice and study the formation of electric field domains and multistability coming from the Coulomb interaction. Phase diagrams of parameter regions (bias, doping in the heterostructure and in the contacts,etc) where the different solutions exist are given.Comment: 4 pages, 8 Postscript Figure

Importancia relativa de especies cuyo polen es utilizado por "Apis mellifera" en el área de la Reserva Nacional Los Ruiles, VII región de Chile

En el presente trabajo, se ha determinado el uso selectivo que Apis mellijfera hace del recurso vegetal de las comunidades de la región mediterránea sub-húmeda de Chile en su recolección de polen. Mediante muestreo sistemático de cúmulos polínicos del polen corbicular, se ha diagnosticado y cuantificado las especies preferidas por las abejas melíferas, y se ha determinado la importancia relativa de cada una de ellas

Boletín de Problemas de Metodología y Tecnología de la Programación

IS04: Metodologia i Tecnologia de la Programació. Curs: 2006/200