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Abdulkerim Karabulut

Publications and source records attributed to Abdulkerim Karabulut.

3 recordsLinked to original sources

Lorentz-Violating Wormhole Optics

We study massless spin-1 field propagation in a static, circularly symmetric $(2+1)$-dimensional wormhole with spatial Lorentz-violating anisotropy characterized by the throat radius $a$ and deformation parameter $η$. The geometry is horizon-free, geodesically complete, and asymptotically flat, with negative Gaussian curvature localized near the throat. Using the fully covariant vector boson formalism and covariant Maxwell theory, we derive an exact Schrödinger-type radial equation with a curvature-induced effective potential. Recasting the dynamics in Helmholtz form yields an effective refractive-index profile, showing that the wormhole acts as an inhomogeneous optical medium with position-dependent refractive index and frequency-dependent confinement, where low-frequency modes are strongly trapped while high-frequency modes propagate almost freely. A differential-geometric correspondence with helicoidal surfaces is established via $1/[a^2(1-η)] \leftrightarrow w^2$, demonstrating that Lorentz-violation-induced curvature is mathematically equivalent to curvature generated by geometric twist and linking the model to twisted graphene nanoribbons as analog-gravity platforms. These results provide a geometric framework for curvature-driven localization, dispersion, and anisotropic wave propagation in topologically nontrivial $(2+1)$-dimensional backgrounds.

gr-qc↗

Wave Propagation and Effective Refraction in Lorentz-Violating Wormhole Geometries

We study the propagation of massless scalar waves in static, spherically symmetric Lorentz-violating wormhole spacetimes within a geometric-optical framework. Starting from a general metric characterized by an arbitrary lapse function and areal radius, we derive curvature invariants, establish regularity conditions at the wormhole throat, and reduce the Klein-Gordon equation to a Helmholtz-type radial wave equation. This formulation naturally leads to a position- and frequency-dependent effective refractive index determined by the underlying spacetime geometry and Lorentz-violating structure, resulting in effective frequency-dependent wave-optical behavior. We show that divergences of the refractive index coincide with Killing horizons, while curvature-induced turning points control reflection, transmission, and confinement of scalar waves. By analyzing constant, linear, and quadratic lapse profiles, we identify horizonless transmission regimes, asymmetric wave propagation, and multi-horizon trapping structures. Our results reveal that Lorentz violation can significantly modify wave-optical properties of curved spacetime, generating graded-index analogues and geometric confinement of modes without curvature singularities. This unified optical perspective provides a robust framework for investigating wave scattering, resonances, and potential observational signatures in Lorentz-violating gravitational backgrounds.

gr-qc↗

Damped photonic modes in helical graphene

We analyze the behavior of spin-1 vector bosons in helical spacetime, focusing on photonic modes in helical graphene structures. We model the helical graphene surface as a smooth, continuous, and distortion-free manifold, effectively adopting the continuum approximation. By solving the fully covariant vector boson equation, we derive exact solutions that describe the quantum states of photons in a curved helical background, revealing their energy spectra, mode profiles, and decay dynamics. We find that the decay times of damped photonic modes range from \(10^{-16}\) to \(10^{-13}\) seconds as the helical pitch (\(a\)) varies from \(10^3\) nanometers to \(1\) nanometer, indicating that the structure efficiently absorbs all photonic modes. Additionally, the probability density functions exhibit time dependence, complementing their spatial variation. These findings provide a foundation for the design of ultrafast graphene photodetectors, graphene photodevices for high-speed optical communications, advanced photonic devices, and quantum materials based on helical graphene for various nanophotonic applications.

cond-mat.mes-hall↗