发表机构
Center for Nanophotonics, NWO Institute AMOLF（纳米光子学中心，荷兰皇家艺术与科学院AMOLF研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过受激近场相互作用合成自由电子波函数，提出分阶段控制方法，在10 keV SEM配置下实现优于先前20%的压缩效果，并利用路径信息调控密度与相干性。
AI 中文摘要
受激电子-光学近场相互作用在自由电子的波函数上印刻一种相干的、相位调制的调制，其自由空间色散随后转化为一串阿秒密度峰。光因此成为合成电子波函数本身的工具，决定了电子密度集中何时、何地以及多窄。这里我们研究光子诱导近场电子显微镜（PINEM），以分两个阶段获得对该合成的控制：首先针对单次PINEM相互作用，其设计参数我们以闭合形式获得；然后针对并行作用的多次PINEM相互作用，这扩展了跨空间和时间的控制。设计规则源于将传播的密度分解为时间谐波，我们将其分为三类：（i）阿秒串的到达时间，由耦合的光学相位固定；（ii）串形成的距离，由所有经典轨迹汇聚点的衍射设定；以及（iii）脉冲持续时间，由印刻的能量展宽固定。我们在10 keV的扫描电子显微镜（SEM）配置下评估这些参数，其中压缩在距相互作用区域几十微米内完成，结果比先前方法好20%。然后让电子与垂直于轨迹的多个空间分离的近场并行相互作用，每条路径携带其自身的耦合强度和光学相位，我们表明保留或擦除路径信息会改变传播的密度和可测量的能量谱，后者反过来提供驱动场相互相干性的度量。这些结果确立了PINEM作为紧凑、低电压电子显微镜中自由电子波函数的定量合成工具。
英文摘要
Stimulated electron-optical-near-field interactions imprint a coherent, phase-coherent modulation on the wave function of a free electron, of which the free-space dispersion subsequently converts into a train of attosecond density peaks. Light thereby becomes a tool for synthesizing the electron wave function itself, setting when, where, and how narrowly the electron density concentrates. Here we study photon-induced near-field electron microscopy (PINEM) to gain control over that synthesis in two stages: first for a single PINEM interaction, whose design parameters we obtain in closed form, and then for multiple PINEM interactions acting in parallel, which extends the control across space and time. The design rules follow from decomposing the propagated density into temporal harmonics, which we classify into three: (i) the arrival time of the attosecond train, fixed by the optical phase of the coupling; (ii) the distance at which the train forms, set by diffraction at the point where all classical trajectories converge; and (iii) the pulse duration, fixed by the imprinted energy spread. We evaluate these parameters for a scanning-electron-microscope (SEM) configuration at 10~keV, where the compression completes within tens of micrometers from the interaction region, with results 20% better than previous approaches. Letting the electron then interact with several spatially separated near fields in parallel, normal to the trajectory, each pathway carrying its own coupling strength and optical phase, we show that retaining or erasing which-path information changes both the propagated density and the measurable energy spectrum, the latter providing in turn a measure of the mutual coherence of the driving fields. These results establish PINEM as a quantitative synthesis tool for free-electron wave functions in compact, low-voltage electron microscopes.
