arXiv subjects

Edilberto O. Silva

Publications and source records attributed to Edilberto O. Silva.

At least 73 records · Page 4Linked to original sources

arXiv2025

Quantum Hall-like effect for neutral particles with magnetic dipole moments in a quantum dot

We predict a new class of quantum Hall phenomena in completely neutral systems, demonstrating that the interplay between radial electric fields and dipole moments induces exact $e^2/h$ quantization without the need for Landau levels or external magnetic fields. Contrary to conventional wisdom, our theory reveals that: (i) the singularity of line charges does not destroy topological protection, (ii) spin-control of quantization emerges from boundary conditions alone, and (iii) the effect persists up to 25 K, surpassing typical neutral systems. These findings establish electric field engineering as a viable route to topological matter beyond magnetic paradigms.

cond-mat.mes-hall↗

arXiv2025

Geometry-Induced Chiral Currents in a Mesoscopic Helicoidal Quantum Well

We introduce a mesoscopic quantum well whose confinement and chirality emerge solely from the intrinsic torsion of a finite helicoidal metric. This purely geometric construction requires no external gates or fields: the metric itself induces both a harmonic radial potential and a torsion-driven Zeeman term that breaks the $m \leftrightarrow -m$ degeneracy. By imposing hard-wall boundary conditions at $z = \pm L/2$, we quantize the axial motion and obtain a genuinely zero-dimensional helicoidal quantum dot. An exact analytic solution reveals an energy spectrum with chiral splitting linear in both the torsion parameter $Ω$ and the axial quantum number $n_z$. For realistic InAs nanoroll parameters ($L = 100$ nm, $Ω= 5\times10^{6} \mathrm{m^{-1}}$), this geometric effect results in a measurable splitting of $\sim 0.5$ meV. We propose three viable experimental platforms, ultracold atoms in optical traps, femtosecond-written photonic waveguides, and strain-engineered semiconductor nanorolls, where this torsion-induced phenomenon should be accessible with current technology.

cond-mat.mes-hall↗

arXiv2025

Geometry-induced Coulomb-like potential in helically twisted quantum systems

In this paper, we investigate the Schrödinger equation in a three-dimensional helically twisted space characterized by a non-trivial torsion parameter. By applying exact separation of variables, we derive the radial equation governing the dynamics of quantum particles in this geometric background. Remarkably, the intrinsic coupling between angular and longitudinal momenta induced by the torsion gives rise to an attractive Coulomb-like potential term that emerges purely from the underlying geometry, without introducing any external fields or interactions. We obtain exact analytical solutions for the bound states, including both the energy spectrum and the normalized wave functions. Numerical calculations are also performed, and excellent agreement with the exact results is found. The interplay between the torsion parameter and the effective Coulomb-like interaction is analyzed in detail, showing how geometric deformation generates novel quantum confinement mechanisms in twisted spaces.

quant-ph↗

arXiv2025

Exact treatment of rotation-induced modifications in two-dimensional quantum rings

We investigate the influence of rotation on the Fermi energy, magnetization, and persistent current in two-dimensional quantum rings. Using the Tan-Inkson confinement potential and incorporating rotational effects through a non-inertial coupling, we derive analytical expressions for the energy levels and examine the modifications induced by rotation. We then numerically explore how variations in angular velocity affect the Fermi energy, magnetization, and persistent current. Our results show that rotation has a significant impact on these physical properties, underscoring the importance of considering rotational effects in quantum ring systems. This suggests that rotation could serve as a control parameter in the development of new mesoscopic devices, without the need for additional fields or geometric modifications.

cond-mat.mes-hall↗

arXiv2025

Spiral dislocation as a tunable geometric parameter for optical responses in quantum rings

We investigate the optical and quantum mechanical properties of a charged spinless particle confined in a two-dimensional quantum ring under the simultaneous influence of a spiral dislocation and an external magnetic field. The dislocation is modeled by a torsion-induced metric that alters the spatial geometry without introducing curvature. Using the minimal coupling procedure in curved space, we derive a modified Schrödinger equation incorporating both topological and electromagnetic effects. The geometric deformation leads to an energy-dependent effective potential, enabling a tunable control over the bound-state spectrum. We analyze how the spiral dislocation modifies the absorption coefficient, refractive index variation, and photoionization cross-section. The results demonstrate that the dislocation not only shifts the resonance peaks but also enhances or suppresses specific optical transitions depending on the angular momentum. These findings open up possibilities for geometrically tuning light-matter interactions in topological quantum devices.

cond-mat.mes-hall↗

arXiv2025

Helically twisted spacetime: study of geometric and wave optics, and physical analysis

We analyse a stationary, cylindrically symmetric spacetime endowed with an intrinsic helical twist, $ds^{2} = -dt^{2} + dr^{2} + r^{2} dϕ^{2} + (dz + ω\, r\,dϕ)^{2}$. Solving the Einstein equations exactly yields an anisotropic energy-momentum tensor whose density is negative and decays as $r^{-2}$, thus violating the weak energy condition near the axis. Three notable features emerge: (i) axis-centred negative energy; (ii) unequal transverse stresses; (iii) a torsional momentum flux $T_{ϕz}ω^{3}/r$. We identify stable photon orbits and deflection angle, fully helical geodesics, and torsion-controlled wave optics modes, suggesting laboratory analogues in twisted liquid-crystal and photonic systems. The coupling between the torsion parameter $ω$ and other physical parameters leads to significant effects, altering the motion along the positive or negative $z$-axis. These results make the twisted helical metric a useful test bed for studying the interplay of curvature, torsion, and matter in both gravitational and condensed-matter contexts.

gr-qc↗

arXiv2025

Rotating effects on the Hall conductivity in a quantum dot

We investigate the behavior of the quantized Hall conductivity in a two-dimensional quantum system under rotating effects, a uniform magnetic field, and an Aharonov-Bohm (AB) flux tube. By varying the angular velocity and the AB flux, we analyze their impact on the formation, shifting, and structure of quantized Hall plateaus. Our results reveal that rotation modifies the energy spectrum, leading to slight shifts in the plateau positions and variations in their widths. Additionally, we identify Aharonov-Bohm-type oscillations in $σ_{\text{Hall}}$, which become more pronounced for lower values of the cyclotron frequency $ω_c$, indicating enhanced quantum interference effects in the low-field regime. These oscillations are further modulated by $Ω$, affecting their periodicity and amplitude. The interplay between the confinement frequency $ω_0$, the cyclotron frequency $ω_c$, and the rotational effects plays a crucial role in determining the overall behavior of $σ_{\text{Hall}}$. Our findings provide insights into the interplay between rotation, magnetic field, and quantum interference effects, which are relevant for experimental investigations of quantum Hall systems in rotating systems.

cond-mat.mes-hall↗

arXiv2025

Impact of the Sagnac Effect on Thermodynamic and Magnetocaloric Properties of a Rotating Two-Dimensional Electron Gas

This work investigates the impact of the Sagnac effect on the thermodynamic properties of a non-interacting two-dimensional electron gas (2DEG) in a rotating sample under the influence of a uniform magnetic field. We derive an analytical expression for the energy spectrum using an effective Hamiltonian that incorporates inertial forces, and then apply canonical ensemble statistical mechanics to evaluate thermodynamic quantities. The results show that rotation modifies the energy levels, the application of a magnetic field leads to the formation of Landau levels further altered by rotation and gravitational mass, and thermodynamic quantities (internal energy, specific heat, free energy, entropy, magnetization, and magnetocaloric effect) exhibit a strong dependence on these parameters. In particular, the difference between effective mass $m^*$ and gravitational mass $m_G$ influences magnetization and the magnetocaloric effect, with negative rotations potentially inducing a cooling effect when these masses are distinct. We conclude that rotational effects and effective mass properties are crucial for understanding the thermodynamics of electronic systems under magnetic fields, with implications for thermal modulation in semiconductor materials.

cond-mat.mes-hall↗

arXiv2025

Modifications in the photoionization cross-section of a quantum dot with position-dependent effective mass

In this work, we investigate the photoionization cross-section of an electron confined in a quantum dot, considering the position-dependent variation of the effective mass through the parameter $γ$. We used a theoretical model based on the Schrödinger equation, in which $γ$ influences the energy levels and wave functions through an effective potential obtained from the harmonic oscillator potential - which, in the limit $γ= 0$, reduces to the original harmonic oscillator potential. Furthermore, we compared the modifications in the photoionization cross-section of these quantum systems with the constant-mass case. Our results demonstrate that even a small variation in $γ$ significantly impacts the photoionization process's amplitude and peak position. We also found that for specific values of $γ$, an inversion occurs: The amplitude, which initially increases as the quantum dot absorbs the photon, begins to decrease. Additionally, we observed that the optical transitions involving the ground state restrict the admissible values of $γ$ to negative values only. These results may have relevant implications for designing optoelectronic devices based on quantum dots with adjustable mass properties.

cond-mat.mes-hall↗

arXiv2025

Fermions in $(1+2)$-dimensions modified by nonminimal coupling and its applications to condensed matter physics

Fermions in two-dimensional space, commonly called $(1+2)$-dimensional fermions, exhibit intriguing and distinctive characteristics that distinguish them from their higher-dimensional counterparts. This paper offers a comprehensive theoretical examination of planar fermionic systems, presenting novel findings by incorporating nonminimal coupling. Our analysis includes the computation of the non-relativistic limit up to second-order corrections in the Dirac equation. We also explore the Schrödinger equation under the influence of a harmonic potential and an electric field. Furthermore, we investigate how the coupling parameter affects physical properties relevant to condensed matter systems. Our results demonstrate that this parameter significantly impacts electronic properties and Hall conductivity. The interplay between an external electric field and the coupling parameter also influences energy levels and the system's polarizability. These findings underscore the novel effects of including nonminimal coupling in wave equations, offering new insights into the physics of coupled systems.

hep-th↗

arXiv2025

Effects of rotation on the thermodynamic properties of a quantum dot

In this work, we investigate the effects of rotation on the physical properties of a quantum dot described by a radial potential and subjected to a rotating reference frame. The interplay between rotation and confinement is analyzed by solving the Schrödinger equation for the system, yielding energy levels and wavefunctions as functions of angular velocity. We compute key thermodynamic properties, including the density of states, magnetization, entropy, and heat capacity, in the absence of an external magnetic field. Our results demonstrate that rotation induces significant modifications to the energy spectrum, removing degeneracies and generating oscillatory behaviors in magnetization akin to de Haas-van Alphen and Aharonov-Bohm-type oscillations. Furthermore, we observe an effect analogous to the magnetocaloric effect, where an increase in angular velocity leads to a decrease in temperature during adiabatic processes. These results reveal the potential of rotational effects to influence quantum systems and provide insights for future studies in mesoscopic physics.

cond-mat.mes-hall↗

arXiv2024

Remarks on the Study of Electronic Properties and Photoionization Process in Rotating 2D Quantum Rings

Electronic and optical properties of a mesoscopic heterostructure of a two-dimensional quantum ring composed of Gallium Arsenide (GaAs) semiconductors are investigated. Using the confinement potential proposed by Tan-Inkson to describe the system under analysis, we conducted a numerical study of the photoionization cross section for a 2D quantum ring with and without rotation effects. The interior of the quantum ring is traversed by an AB flux. Our research aims to investigate how this mesoscopic structure's electronic and optical properties respond to variations in the following parameters: average radius, AB flux, angular velocity, and incident photon energy. Under these conditions, we establish that optical transitions occur from the ground state to the next excited state in the conduction sub-band, following a specific selection rule. One of the fundamental objectives of this study is to analyze how these rules can influence the general properties of two-dimensional quantum rings. To clarify the influence of rotation on the photoionization process within the system, we offer findings that illuminate the effects of the pertinent physical parameters within the described model. We emphasize that, although this is a review, it provides critical commentary, analysis, and new perspectives on existing research. Some results presented in this paper can be compared with those in the literature; however, new physical parameters and quantum ring configurations are used.

cond-mat.mes-hall↗

arXiv2024

Dynamics of massive and massless particles in the spacetime of a wiggly cosmic dislocation

In this paper, we investigate the spacetime containing both small-scale structures (wiggles) and spatial dislocation, forming a wiggly cosmic dislocation. We study the combined effects of these features on the dynamics of massive and massless particles. Our results show that while wiggles alone lead to bound states and dislocation introduces angular momentum corrections, their coupling produces more complex effects, influencing both particle motion and wave propagation. Notably, this coupling significantly modifies radial solutions and eigenvalues, with the direction of motion or propagation becoming a critical factor in determining the outcomes. Numerical solutions reveal detailed aspects of particle dynamics as functions of dislocation and string parameters, including plots of trajectories, radial probability densities, and energy levels. These findings deepen our understanding of how a wiggly cosmic dislocation shapes particle dynamics, suggesting new directions for theoretical exploration in cosmological models.

hep-th↗

arXiv2024

Nonlinear refractive index changes and absorption coefficients in mesoscopic ring induced by variable effective mass

This study explores the linear and nonlinear optical absorption coefficients (OAC) and refractive index changes (RIC) in quantum dot and quantum antidot systems with a position-dependent variable effective mass. Significant contributions to both linear and nonlinear OAC and RIC are observed. Our findings reveal that variations of the mass parameter modify the intersubband dipole matrix elements and energy intervals, leading to noticeable shifts in optical properties. The results show that higher γ values shift resonance peaks towards higher energies, while changes in the oscillator frequency result in abrupt shifts and peak diminutions. These insights provide a deeper understanding of the optical behaviors in the quantum systems under consideration, paving the way for designing devices with optimal efficiency

physics.optics↗

arXiv2024

Thermodynamic properties of an electron gas in a two-dimensional quantum dot: an approach using density of states

Potential applications of quantum dots in the nanotechnology industry make these systems an important field of study in various areas of physics. In particular, thermodynamics has a significant role in technological innovations. With this in mind, we studied some thermodynamic properties in quantum dots, such as entropy and heat capacity, as a function of the magnetic field over a wide range of temperatures. The density of states plays an important role in our analyses. At low temperatures, the variation in the magnetic field induces an oscillatory behavior in all thermodynamic properties. The depopulation of subbands is the trigger for the appearance of the oscillations.

cond-mat.mes-hall↗

arXiv2024

Rotating effects on the photoionization cross-section of a 2D quantum ring

In this letter, we investigate the nonrelativistic quantum motion of a charged particle within a rotating frame, taking into account the Aharonov-Bohm (AB) effect and a uniform magnetic field. Our analysis entails the derivation of the equation of motion and the corresponding radial equation to describe the system. Solving the resulting radial equation enables us to determine the eigenvalues and eigenfunctions, providing a clear expression for the energy levels. Furthermore, our numerical analysis highlights the substantial influence of rotation on both energy levels and optical properties. Specifically, we evaluate the photoionization cross-section (PCS) with and without the effects of rotation. To elucidate the impact of rotation on the photoionization process of the system, we present graphics that offer an appealing visualization of the intrinsic nature of the physics involved.

cond-mat.mes-hall↗

arXiv2023

Cosmic string influence on a 2D hydrogen atom and its relationship with the Rytova-Keldysh logarithmic approximation in semiconductors

A two-dimensional hydrogen atom offers a promising alternative for describing the quantum interaction between an electron and a proton in the presence of a straight cosmic string. Reducing the hydrogen atom to two dimensions enhances its suited to capture the cylindrical/conical symmetry associated with the cosmic string, providing a more appropriate description of the physical system. After solving Schrdinger's equation, we calculate the eigenenergies, probability distribution function, and expected values for the hydrogen atom with logarithmic potential under the influence of the topological defect. The calculations for the 2D hydrogen atom are performed for the first time using the Finite Difference Method. The results are presented through graphics, tables, and diagrams to elucidate the system's physical properties. We have verified that our calculations agree with a linear variational method result. Our model leads to an interesting analogy with excitons in a two-dimensional monolayer semiconductor located within a specific semiconductor region. To elucidate this analogy, we present and discuss some interaction potentials and their exciton eigenstates by comparing them with the results from the literature.

quant-ph↗

arXiv2023

Study on the effects of anisotropic effective mass on electronic properties, magnetization and persistent current in semiconductor quantum ring with conical geometry

We study a 2D mesoscopic ring with an anisotropic effective mass considering surface quantum confinement effects. Consider that the ring is defined on the surface of a cone, which can be controlled topologically and mapped to the 2D ring in flat space. We demonstrate through numerical analysis that the electronic properties, the magnetization, and the persistent current undergo significant changes due to quantum confinement and non-isotropic mass. We investigate these changes in the direct band gap semiconductors SiC, ZnO, GaN, and AlN. There is a plus (or minus) shift in the energy sub-bands for different values of curvature parameter and anisotropy. Manifestations of this nature are also seen in the Fermi energy profile as a function of the magnetic field and in the ring width as a function of the curvature parameter. Aharonov-Bohm (AB) and de Haas van-Alphen (dHvA) oscillations are also studied, and we find that they are sensitive to variations in curvature and anisotropy.

cond-mat.mes-hall↗