Light-induced Pairing Instability of Ultrafast Electron Beams with Space Charge Interactions

Hao Geng; Qiaofei Pan; Jian Kang; Yiming Pan

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arXiv · 2507.00869

Light-induced Pairing Instability of Ultrafast Electron Beams with Space Charge Interactions

Hao Geng·Qiaofei Pan·Jian Kang·Yiming Pan

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Abstract

Ultrafast electron beams are essential for many applications, yet space-charge interactions in high-intensity beams lead to energy dissipation, coherence loss, and pulse broadening. Existing techniques mitigate these effects by using low-flux beams, preserving beam coherence into the quantum regime. Here, we propose a novel approach by treating the electrons as a strongly correlated Fermi gas rather than merely as an ensemble of charged point-like particles. We introduce a photon-induced pairing mechanism that generates a net attractive force between two electrons, thereby forming "flying bound states" analogous to Cooper pairs of conduction electrons in superconductors. Employing the setting of photon-induced near-field electron microscopy (PINEM), we demonstrate that the effective interaction via single-photon exchange among PINEM electrons can suppress the inherent repulsive Coulomb interaction, enabling a pairing instability mediated by structured electromagnetic fields at near-resonant velocity matching regimes. Finally, we analyze the dynamics of the free-electron pairs in a bunched beam, underscoring the potential to facilitate a phase-coherent condensate of electrons, which can further enhance beam coherence and multi-particle correlation for high-intensity electrons.

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Hao Geng, Qiaofei Pan, Jian Kang, Yiming Pan. 2025-07-01. Light-induced Pairing Instability of Ultrafast Electron Beams with Space Charge Interactions. https://arxiv.org/abs/2507.00869

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