Modelo de Ingreso de Datos a la Herramienta de Costos del Sistema de Transporte Público de Pasajeros

Las pequeñas y medianas ciudades se enfrentan a una serie de dificultades a la hora de administrar y manejar su sistema de transporte urbano. Esta problemática se debe a que no cuentan con los métodos necesarios para analizar y administrar los recursos que poseen. Surgida esta necesidad, el propósito de este estudio es recabar los datos necesarios para operar una herramienta de costos del sistema de transporte público que se pueda emplear para el cálculo de costos en ciudades con características similares. El mecanismo de implementación consiste en la interacción de los usuarios a través de preguntas que permitan segmentar el servicio que brindan en un escenario en particular y, por medio de esta categorización, poder brindar los parámetros e información pertinente al entorno que se encuentran. Como resultado final del proceso, a través de fórmulas matemáticas de costos, el sistema entregará como salida, el valor buscado del costo

Ultrastrong Coupling of Si1−xGex Parabolic Quantum Wells toTerahertz Microcavities

Control and manipulation of quantum states by light are increasingly important for both fundamental research and applications. This can be achieved through the strong coupling between light and semiconductor devices, typically observed at THz frequencies in 2D electron gases embedded in lithographic optical cavities. Here, we explore the possibility of achieving ultrastrong coupling between conduction sub-band states in Si1–xGex heterostructures and THz cavity photons fabricated with a potentially silicon-CMOS-compliant process. We developed Si1–xGex parabolic quantum wells with a transition at ω0 = 3.1 THz and hybrid metal-plasmonic THz patch-antenna microcavities resonating between 2 and 5 THz depending on the antenna length. In this first demonstration, we achieved anticrossing around 3 THz with spectroscopically measured Rabi frequency ΩR ≃ 0.7 THz (ΩR/ω0 ≃ 0.2, i.e., ultrastrong coupling). The present group-IV semiconductor material platform can be extended to the 5–12 THz range, where these semiconductors are transparent, as opposed to the III–V compound semiconductors plagued by strong THz optical phonon absorption. Moreover, the intersubband transition in parabolic quantum wells hosted by the nonpolar Si1–xGex crystal lattice is robust against carrier density and temperature variations, making the strength of the coupling only weakly temperature-dependent from 10 to 300 K. These results pave the way for the employment of the Si1–xGex material platform to perform fundamental research in ultrastrong light–matter coupling, fully exploiting the plasmonic character of the cavity mirror, as well as in ultrafast modulators and saturable absorbers for THz laser research

Modelo de Ingreso de Datos a la Herramienta de Costos del Sistema de Transporte Público de Pasajeros

The small and medium-sized cities face many difficulties in administrating and managing their urban transport system. This trouble is due to they do not have the necessary methods to analyze and manage the resources that they have. With this necessity in mind, the purpose of this study is to collect the necessary data to operate a cost tool that can be used for costing the public transport cost in cities with similar characteristics.The implementation mechanism consists in the interaction of the users through questions that allow to segment the service that they offer in a particular scenario and, through this categorization, to be able to provide parameters and information pertinent to the environment that they are. As a final result of the process, through mathematical formulas of costs, the system will deliver as output, the sought value of the cost.Las pequeñas y medianas ciudades se enfrentan a una serie de dificultades a la hora de administrar y manejar su sistema de transporte urbano. Esta problemática se debe a que no cuentan con los métodos necesarios para analizar y administrar los recursos que poseen. Surgida esta necesidad, el propósito de este estudio es recabar los datos necesarios para operar una herramienta de costos del sistema de transporte público que se pueda emplear para el cálculo de costos en ciudades con características similares. El mecanismo de implementación consiste en la interacción de los usuarios a través de preguntas que permitan segmentar el servicio que brindan en un escenario en particular y, por medio de esta categorización, poder brindar los parámetros e información pertinente al entorno que se encuentran.Como resultado final del proceso, a través de fórmulas matemáticas de costos, el sistema entregará como salida, el valor buscado del costo

High-quality CMOS compatible n-type SiGe parabolic quantum wells for intersubband photonics at 2.5–5 THz

A parabolic potential that confines charge carriers along the growth direction of quantum wells semiconductor systems is characterized by a single resonance frequency, associated to intersubband transitions. Motivated by fascinating quantum optics applications leveraging on this property, we use the technologically relevant SiGe material system to design, grow, and characterize n-type doped parabolic quantum wells realized by continuously grading Ge-rich Si1-xGex alloys, deposited on silicon wafers. An extensive structural analysis highlights the capability of the ultra-high-vacuum chemical vapor deposition technique here used to precisely control the quadratic confining potential and the target doping profile. The absorption spectrum, measured by means of Fourier transform infrared spectroscopy, revealed a single peak with a full width at half maximum at low and room temperature of about 2 and 5 meV, respectively, associated to degenerate intersubband transitions. The energy of the absorption resonance scales with the inverse of the well width, covering the 2.5-5 THz spectral range, and is almost independent of temperature and doping, as predicted for a parabolic confining potential. On the basis of these results, we discuss the perspective observation of THz strong light-matter coupling in this silicon compatible material system, leveraging on intersubband transitions embedded in all-semiconductor microcavities

Subnanometer Control of the Heteroepitaxial Growth of Multimicrometer-Thick Ge/(Si,Ge) Quantum Cascade Structures

The fabrication of complex low-dimensional quantum devices requires the control of the heteroepitaxial growth at the subnanometer scale. This is particularly challenging when the total thickness of stacked layers of device-active material becomes extremely large and exceeds the multi-μm limit, as in the case of quantum cascade structures. Here, we use the ultrahigh-vacuum chemical vapor deposition technique for the growth of multi-μm-thick stacks of high Gecontent strain-balanced Ge/SiGe tunneling heterostructures on Si substrates, designed to serve as the active material in a THz quantum cascade laser. By combining thorough structural investigation with THz spectroscopy absorption experiments and numerical simulations we show that the optimized deposition process can produce state-of-the-art threading dislocation density, ultrasharp interfaces, control of dopant atom position at the nanoscale, and reproducibility within 1% of the layer thickness and composition within the whole multilayer. We show that by using ultrahigh-vacuum chemical vapor deposition one achieves simultaneously a control of the epitaxy down to the sub-nm scale typical of the molecular beam epitaxy, and the high growth rate and technological relevance of chemical vapor deposition. Thus, this technique is a key enabler for the deposition of integrated THz devices and other complex quantum structures based on the Ge/SiGe material system