Revivals, classical periodicity, and zitterbewegung of electron currents in monolayer graphene

Revivals of electric current in graphene in the presence of an external magnetic field are described. It is shown that when the electrons are prepared in the form of wave packets assuming a Gaussian population of only positive (or negative) energy Landau levels, the presence of the magnetic field induce revivals of the electron currents, besides the classical cyclotron motion. When the population comprises both positive and negative energy Landau levels, revivals of the electric current manifest simultaneously with zitterbewegung and the classical cyclotron motion. We relate the temporal scales of these three effects and discuss to what extent these results hold for real graphene samples

Identifying wave packet fractional revivals by means of information entropy

Wave packet fractional revivals is a relevant feature in the long time scale evolution of a wide range of physical systems, including atoms, molecules and nonlinear systems. We show that the sum of information entropies in both position and momentum conjugate spaces is an indicator of fractional revivals by analyzing three different model systems: $(i)$ the infinite square well, $(ii)$ a particle bouncing vertically against a wall in a gravitational field, and $(iii)$ the vibrational dynamics of hydrogen iodide molecules. This description in terms of information entropies complements the usual one in terms of the autocorrelation function

Influencia de la exposición a la violencia en conductas de agresión en cyberbullying

En el presente trabajo se ha tratado de explorar el fenómeno del cyberbullying, un tipo de maltrato entre iguales reciente cuya trascendencia va en aumento, y su relación con la exposición a la violencia en los contextos donde los jóvenes se desarrollan. El objetivo está dirigido a conocer si las experiencias previas de exposición a situaciones violentas podrían estar vinculadas a una mayor implicación en conductas de agresión en cyberbullying. Para ello, se tomó una muestra de 328 estudiantes de Educación Secundaria Obligatoria, a los que se les administró el Cuestionario de cyberbullying (Ang & Goh, 2010) y el Cuestionario de exposición a la violencia (Orúe & Calvate, 2010). Un análisis de regresión lineal mostró que existe una fuerte relación entre haber sido expuesto a sucesos violentos en el hogar y participar en actos de cyberbullying. La exposición a la violencia en el vecindario y, en último lugar, el contexto escolar también explican una parte sustancial de la implicación en este tipo de acoso. Las conclusiones subrayan la importancia de la observación de los episodios violentos en la implicación en cybermaltrato, teniendo en algunos casos una contribución más significativa que la propia victimización directa.This paper has attempted to explore cyberbullying, a recent type of bullying which importance is increasing, and the exposure to violence in contexts where young people are usually relating. The aim is to know if the previous experiences of exposure to violent situations could be linked to greater involvement in aggressive behavior in cyberbullying. For this purpose, a sample of 328 students of secondary school was taken. Instruments were Cyberbullying Questionnaire (Ang and Goh, 2010) and the Questionnaire of Exposure to Violence (Orúe & Calvate, 2010). Linear regression analysis showed a strong relationship between being exposed to violent events at home and engaged in acts of cyberbullying. Exposure to violence in the neighborhood and, finally, the school context also explain a substantial part of the involvement in this type of harassment. Conclusions focus the importance of the observation of violent episodes in the implication in cyberbbullying, having in some cases more significant contribution than the own direct victimization

Quantum recurrence times in nanostructures

We compute the classical and revival times of electron currents in several bulk nanostructured, semiconductor materials. We have used a nonparabolic Schrödinger equation to model the conduction band of semiconductors. We have calculated the classical and revival periods for quantum dots of Si, Ge and InAs quantum dots. The obtained results are of the order of tenths of nanoseconds to picoseconds, which are within reach of current technologies.This work is part of the Project of I+D+i Ref. PID2020-113681GB-I00, financed by MICIN/AEI/10.13039/501100011033 and FEDER “A way to make Europe”