39 research outputs found
Resonant-state expansion of the Green's function of open quantum systems
Our series of recent work on the transmission coefficient of open quantum
systems in one dimension will be reviewed. The transmission coefficient is
equivalent to the conductance of a quantum dot connected to leads of quantum
wires. We will show that the transmission coefficient is given by a sum over
all discrete eigenstates without a background integral. An apparent
"background" is in fact not a background but generated by tails of various
resonance peaks. By using the expression, we will show that the Fano asymmetry
of a resonance peak is caused by the interference between various discrete
eigenstates. In particular, an unstable resonance can strongly skew the peak of
a nearby resonance.Comment: 7 pages, 7 figures. Submitted to International Journal of Theoretical
Physics as an article in the Proceedings for PHHQP 2010
(http://www.math.zju.edu.cn/wjd/
Pseudo-time Schroedinger equation with absorbing potential for quantum scattering calculations
The Schroedinger equation with an energy-dependent complex absorbing
potential, associated with a scattering system, can be reduced for a special
choice of the energy-dependence to a harmonic inversion problem of a discrete
pseudo-time correlation function. An efficient formula for Green's function
matrix elements is also derived. Since the exact propagation up to time 2t can
be done with only t real matrix-vector products, this gives an unprecedently
efficient scheme for accurate calculations of quantum spectra for possibly very
large systems.Comment: 9 page
Time Asymmetric Quantum Physics
Mathematical and phenomenological arguments in favor of asymmetric time
evolution of micro-physical states are presented.Comment: Tex file with 2 figure
The Hyperspherical Four-Fermion Problem
The problem of a few interacting fermions in quantum physics has sparked
intense interest, particularly in recent years owing to connections with the
behavior of superconductors, fermionic superfluids, and finite nuclei. This
review addresses recent developments in the theoretical description of four
fermions having finite-range interactions, stressing insights that have emerged
from a hyperspherical coordinate perspective. The subject is complicated, so we
have included many detailed formulas that will hopefully make these methods
accessible to others interested in using them. The universality regime, where
the dominant length scale in the problem is the two-body scattering length, is
particularly stressed, including its implications for the famous BCS-BEC
crossover problem Derivations and relevant formulas are also included for the
calculation of challenging few-body processes such as recombination.Comment: 66 pages, 33 figure
Dise帽o de modelo de negocios para nuevo Servicio tipo Saas en empresa de votaci贸n electr贸nica
Ingeniero Civil IndustrialEl objetivo general de este trabajo de memoria es dise帽ar un modelo de negocios para una nueva plataforma tipo SaaS de votaci贸n electr贸nica por internet. El trabajo se encuentra patrocinado por la empresa EVoting, l铆der nacional en votaciones electr贸nicas.
En la actualidad, no existen sistemas de este tipo en Chile, siendo el principal sustituto el sistema tradicional de votaciones a trav茅s de papel. El problema con 茅ste es que requiere de un esfuerzo, por parte del votante, en tiempo y recursos para sufragar, lo que en muchos casos provoca bajas participaciones en los procesos eleccionarios y consultivos. Adem谩s, para la organizaci贸n tambi茅n es un esfuerzo el montaje de estas instancias.
Por estos motivos, el siguiente proyecto presenta la creaci贸n y evaluaci贸n del modelo de negocios para esta plataforma web. La metodolog铆a que se utiliz贸 como base es Running Lean, la cual centra su proceso en la herramienta Lean Canvas, cuyo foco est谩 puesto en construir el modelo de negocios iterando, validando distintos elementos en base a conversaciones con potenciales clientes.
Se determin贸 como segmento objetivo m谩s atractivo para comenzar la evaluaci贸n a las Juntas de Vecinos, organizaciones territoriales cuyo objetivo es incentivar la participaci贸n, integraci贸n y desarrollo de las comunidades de vecinos. Lo primero que se hizo fue realizar un ajuste del problema/soluci贸n, validando los problemas presentados en un principio. Luego se realiza una propuesta de soluci贸n que es validada con el segmento, con lo que se construye un Producto M铆nimo Viable que es testeado cuantitativamente. En cada proceso se va iterando el Lean Canvas.
Se propuso utilizar un modelo de captaci贸n y retenci贸n de clientes, llamado CASAR, mediante el cual se definieron sistemas para la captura, sostenimiento, recuperaci贸n, crecimiento, referenciaci贸n y devoluci贸n a la sociedad.
La evaluaci贸n econ贸mica del proyecto se hizo a trav茅s de un flujo de caja con un horizonte de 3 a帽os, utilizando una tasa de descuento de 20%, con lo que se obtuvo un VAN de CLP$20.313.573, concluyendo que el negocio es atractivo para ser realizado.
Finalmente se propusieron una serie de actividades para realizar en el futuro, con el objetivo de poner en marcha el negocio
AdaGAN: Boosting Generative Models
Generative Adversarial Networks (GAN) (Goodfellow et al., 2014) are an
effective method for training generative models of complex data such as natural
images. However, they are notoriously hard to train and can suffer from the
problem of missing modes where the model is not able to produce examples in
certain regions of the space. We propose an iterative procedure, called AdaGAN,
where at every step we add a new component into a mixture model by running a
GAN algorithm on a reweighted sample. This is inspired by boosting algorithms,
where many potentially weak individual predictors are greedily aggregated to
form a strong composite predictor. We prove that such an incremental procedure
leads to convergence to the true distribution in a finite number of steps if
each step is optimal, and convergence at an exponential rate otherwise. We also
illustrate experimentally that this procedure addresses the problem of missing
modes.Comment: Updated with MNIST pictures and discussions + Unrolled GAN
experiment