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Jeferson Danilo L. Silva

Publications and source records attributed to Jeferson Danilo L. Silva.

7 recordsLinked to original sources
arXiv2024

Polarization and energy ellipsoids for an introductory visualization of tensors

In ``The Feynman Lectures on Physics'' is discussed an introduction to tensors by means of the polarization tensor, including a way of ``visualizing'' this tensor via the energy ellipsoid, which is drawn by the electric fields which produce the same polarization energy density in an anisotropic crystal. Here, we discuss an alternative way of visualizing the polarization tensor, by means of the polarization ellipsoid, which is based on the ideas of Lamé's stress ellipsoid and is drawn by the polarization vectors produced by electric fields having the same magnitude. We compare both ellipsoids as a first introductory way of visualizing the polarization tensor.

physics.ed-ph↗
arXiv2023

Renormalization of the band gap in 2D materials near an interface between two dielectrics

We investigate how the renormalization of the band gap in a planar 2D material is affected by the consideration of two nondispersive semi-infinite dielectrics, with dielectric constants $ε_1$ and $ε_2$, separated by a planar interface. Using the pseudo quantum electrodynamics to model the Coulomb interaction between electrons, we show how the renormalization of the band gap depends on $ε_1$ and $ε_2$, and also of the distance between the 2D material and the interface between the two dielectrics. In the appropriate limits, our results reproduce those found in the literature for the band gap renormalization when a single dielectric medium is considered.

hep-th↗
arXiv2021

Dynamical Casimir effect enhanced by decreasing the mirror reflectivity

In the present paper, we show that a partially reflecting static mirror with time-dependent properties can produce, via dynamical Casimir effect in the context of a massless scalar field in $1+1$ dimensions, a larger number of particles than a perfectly reflecting one. As particular limits, our results recover those found in the literature for a perfect static mirror imposing a generalized or an usual time-dependent Robin boundary condition.

quant-ph↗
arXiv2020

Motion induced by asymmetric excitation of the quantum vacuum

During the last fifty-one years, the effect of excitation of the quantum vacuum field induced by its coupling with a moving object has been systematically studied. Here, we propose and investigate a somewhat inverted setting: an object, initially at rest, whose motion becomes induced by an excitation of the quantum vacuum caused by the object itself. In the present model, this excitation occurs asymmetrically on different sides of the object by a variation in time of one of its characteristic parameters, which couple it with the quantum vacuum field.

quant-ph↗
arXiv2016

Dynamical Casimir effect with $δ-δ^{\prime}$ mirrors

We calculate the spectrum and the total rate of created particles for a real massless scalar field in $1+1$ dimensions, in the presence of a partially transparent moving mirror simulated by a Dirac $δ-δ^{\prime}$ point interaction. We show that, for this model, a partially reflecting mirror can produce a larger number of particles in comparison with a perfect one. In the limit of a perfect mirror, our formulas recover those found in the literature for the particle creation by a moving mirror with a Robin boundary condition.

quant-ph↗
arXiv2016

Casimir force between $δ-δ^{\prime}$ mirrors transparent at high frequencies

We investigate, in the context of a real massless scalar field in $1+1$ dimensions, models of partially reflecting mirrors simulated by Dirac $δ-δ^{\prime}$ point interactions. In the literature, these models do not exhibit full transparency at high frequencies. In order to provide a more realistic feature for these models, we propose a modified $δ-δ^{\prime}$ point interaction that enables full transparency in the limit of high frequencies. Taking this modified $δ-δ^{\prime}$ model into account, we investigate the Casimir force, comparing our results with those found in the literature.

quant-ph↗