arXiv subjects

Furkan Ok

Publications and source records attributed to Furkan Ok.

3 recordsLinked to original sources

arXiv2025

Access to Klein Tunneling via Space-Time Modulation

We show that space-time modulation of electromagnetic potentials enables Klein tunneling far below the static threshold. The derived kinematics reveal oblique transitions that can connect opposite-energy continua without requiring their overlap, yielding a velocity-tunable Klein gap where transmission vanishes within a finite velocity window and reemerges beyond. The associated reduction in energy thresholds -- by up to four orders of magnitude -- suggests the potential for experimental realization using flying-focus fronts and relativistic electron beams.

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arXiv2024

Electron Scattering at a Potential Temporal Step Discontinuity

We solve the problem of electron scattering at a potential temporal step discontinuity. We show that the Schrodinger equation cannot account for scattering in this problem, necessitating resort to the Dirac equation, and that breaking gauge symmetry requires a vector potential, a scalar potential inducing only Aharonov-Bohm type energy transitions. We derive the scattering probabilities, of later forward and backward nature, with the later-backward wave being a relativistic effect, and compare the results with those for the spatial step and classical electromagnetic counterparts of the problem. Given the unrealizability of an infinitely sharp temporal discontinuity - which is of the same nature as its spatial counterpart! - we also provide solutions for a smooth potential step and demonstrate that the same physics as for the infinitely sharp case is obtained when the duration of the potential transition is sufficiently smaller than the de Broglie period of the electron (or deeply sub-period).

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arXiv2024

Electron Scattering at a Soft Temporal Potential Step

We solve the problem of electron scattering at a soft temporal potential step. Given the relativistic nature of the problem, we use the Dirac equation, with its spinor wavefunction. We find solutions in terms of hypergeometric functions, which demonstrate that the observed phenomenon of later forward-wave and backward-wave electron scattering previously reported for a sharp (Heaviside) temporal potential step can be obtained experimentally and applied to new electronic devices.

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