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

Venezuela’s Growth Experience

The standard of living, measured as gross domestic product (GDP) per capita, increased dramatically in Venezuela relative to that of the United States from 20 percent in 1920 to 90 percent in 1958, but since then has collapsed to around 30 percent nowadays. What explains these remarkable growth and collapse episodes? Using a standard development accounting framework, we show that the growth episode is mainly accounted for by an increase in capital accumulation and knowledge transfer associated with the foreign direct investment in the booming oil industry. The collapse episode is accounted for equally by a fall in total factor productivity and in capital accumulation. We analyze Venezuela during the collapse episode in the context of a model of heterogeneous production units were policies and institutions favour unproductive in detriment of more productive activities. These policies generate misallocation, lower TFP, and a decline in capital accumulation. We show in the context of an heterogeneous-establishment growth model that distortionary policies can explain a large portion of the current differences in TFP, capital accumulation, and income per capita between Venezuela and the United States.Productivity, physical capital, misallocation, policies

Venezuela's Growth Experience

The standard of living, measured as gross domestic product (GDP) per capita, increased dramatically in Venezuela relative to that of the United States from 20 percent in 1920 to 90 percent in 1958, but since then has collapsed to around 30 percent nowadays. What explains these remarkable growth and collapse episodes? Using a standard development accounting framework, we show that the growth episode is mainly accounted for by an increase in capital accumulation and knowledge transfer associated with the foreign direct investment in the booming oil industry. The collapse episode is accounted for equally by a fall in total factor productivity and in capital accumulation. We analyze Venezuela during the collapse episode in the context of a model of heterogeneous production units were policies and institutions favour unproductive in detriment of more productive activities. These policies generate misallocation, lower TFP, and a decline in capital accumulation. We show in the context of an heterogeneous-establishment growth model that distortionary policies can explain between 80 to 95 percent of the current differences in TFP, capital accumulation, and income per capita between Venezuela and the United States.Productivity, physical capital, misallocation, policies

Fifteenth-century merchants in Jerez de la Frontera

Gracias a una serie de circunstancias económicas y sociales Jerez de la Frontera pudo atraer a un considerable número de comerciantes, nacionales y extranjeros, que se establecieron en la ciudad a lo largo del siglo XV. Con la rica documentación de su Archivo Municipal, con los Protocolos Notariales disponibles y con documentación procedente de los Archivos Nacionales, en éste trabajo se pretende dar a conocer algunas de las causas por las que la ciudad contó con un nutrido grupo de mercaderes así como las relaciones que muchos de ellos mantuvieron con sus homólogos del resto de Andalucía.Fostered by a set of economic and social circumstances, Jerez de la Frontera caught the attention of an outstanding number of merchants, both national and foreign, who settled down in town throughout the fifteenth century. This work tries to account for the remarkable figures concerning these merchants, as well as for their relationships with traders coming from the rest of Andalusia. The documents and notarial registries used as sources will be those available at National Archives

Merchants' Account and the Petty Customs of the Seville Almojarifago Major at the end of the 15th Century

: Con un fondo documental excepcional procedente de los archivos de Simancas y Real Chancillería de Valladolid que recogen la contribución de varios centenares de mercaderes al almojarifazgo mayor de Sevilla y la declaración detallada del valor de las llamadas rentas menudas de dicho almojarifazgo, en este trabajo se ofrecen nuevos datos sobre la evolución de esta renta en la ciudad de Sevilla a finales de la Edad Media.This work offers new evidence about the evolution of custom duties in the city of Seville by the end of the Middle Ages. Its exceptional sources are located in the Simancas Record Office and in that of Valladolid Royal Chancery. The files contain the contributions issued by hundreds of merchants to the Sevillian Almojarifazgo Major rentas menudas (custom duty) and their detailed tax declaration concerning the worth of the so called “petty customs” in that particular almojarifazgo