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arXiv · 2510.21154

Access to Klein Tunneling via Space-Time Modulation

Furkan Ok·Amir Bahrami·Christophe Caloz
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Abstract

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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Furkan Ok, Amir Bahrami, Christophe Caloz. 2025-10-24. Access to Klein Tunneling via Space-Time Modulation. https://doi.org/10.1016/j.aop.2026.170686

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