标题： 超快电子束与空间电荷相互作用的光致配对不稳定性 显示英文标题

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

摘要： 超快电子束对于许多应用至关重要，然而高强度束中的空间电荷相互作用会导致能量耗散、相干性丧失和脉冲展宽。 现有技术通过使用低通量束来减轻这些效应，从而将束的相干性保持在量子领域。 在此，我们提出了一种新方法，将电子视为强关联的费米气体，而不仅仅视为带电点粒子的集合。 我们引入了一种光子诱导的配对机制，该机制在两个电子之间产生净吸引力，从而形成类似于超导体中传导电子库珀对的“飞行束缚态”。 利用光子诱导近场电子显微镜（PINEM）的设置，我们证明了PINEM电子之间的单光子交换有效相互作用可以抑制固有的库仑排斥相互作用，在接近共振速度匹配的区域，通过结构化的电磁场介导的配对不稳定性得以实现。 最后，我们分析了束流中自由电子对的动力学，强调了促进电子相位相干凝聚的潜力，这可以进一步增强高强度电子的束相干性和多粒子关联。 显示英文摘要

摘要： 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.