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The purpose of this tutorial paper is to present a broad overview of photon-pair generation through the spontaneous four wave mixing (SFWM) process in optical fibers. Progress in optical fiber technology means that today we have at our disposal a wide variety of types of fiber, which, together with the fact that SFWM uses two pump fields, implies a truly remarkable versatility in the resulting possible photon-pair properties. We discuss how the interplay of frequency, transverse mode, and polarization degrees of freedom—the first linked to the latter two through fiber dispersion—leads to interesting entanglement properties both in individual degrees of freedom and also permitting hybrid and hyper entanglement in combinations of degrees of freedom. This tutorial covers methods for photon-pair factorability, frequency tunability, and SFWM bandwidth control, the effect of frequency non-degenerate and counterpropagating pumps, as well as methods for characterizing photon pairs generated in optical fibers. 

Colombia es un país con alta diversidad de hormigas, sin embargo, nuevos taxones se siguen registrando para el país. Cuarenta y siete nuevos registros se relacionan aquí, todos dentro de la subfamilia Myrmicinae: Uno para los géneros Adelomyrmex, Allomerus, Kempfidris, Megalomyrmex, Octostruma y Tranopelta; dos para Rogeria; cinco para Myrmicocrypta; seis para Procryptocerus; siete para Cephalotes; diez para Pheidole y once para Strumigenys. Tres de esos nuevos registros corresponden a especies invasoras, Pheidole indica, Strumigenys emmae y Strumigenys membranifera. Tres especies se citan por primera vez para América del Sur: Pheidole sicaria, Procryptocerus tortuguero y Strumigenys manis. El género Kempfidris se registra por primera vez para Colombia. Se ofrecen comentarios para todas las especies. La diversidad de hormigas en Colombia comprende 104 géneros y casi 1.100 especies.