Dielectric laser accelerators (DLAs) hold great promise for producing economic and compact on-chip radiation sources. On-chip DLAs benefit from fabrication capabilities of the silicon industry and from breakthroughs in silicon-photonic nanostructures to enhance the interaction between particles and laser fields. Seemingly unrelated recent advances in the quantum interactions of electrons and light have raised interest in the underlying classical-quantum correspondence principle at the foundations of electron acceleration. Here, we present the observation of the underlying quantum nature of DLAs: observing quantized peaks in the electron-energy spectra. Our findings demonstrate quasi-phase-matching between an electron wave function and a light wave, which also demonstrates the role of the quantum wave function in the inverse Smith-Purcell effect. We harness the capabilities of an ultrafast transmission electron microscope (UTEM) to maintain a long electron-light interaction length extending over hundreds of periods of the laser pulse, mediated by a silicon-photonic nanograting DLA. The UTEM is shown as a new platform for characterization of future DLA concepts. The results raise fundamental questions regarding the role of quantum mechanics in DLA design, and more generally about the prospects of manipulating particles’ quantum wave functions in accelerator physics.

中文翻译：

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介电激光加速器的量子性质

介电激光加速器 (DLA) 有望用于生产经济且紧凑的片上辐射源。片上 DLA 受益于硅工业的制造能力和硅光子纳米结构的突破，以增强粒子与激光场之间的相互作用。最近在电子和光的量子相互作用中看似无关的进展引起了人们对作为电子加速基础的经典-量子对应原理的兴趣。在这里，我们展示了对 DLA 潜在量子性质的观察：观察电子能谱中的量子化峰。我们的发现证明了电子波函数和光波之间的准相位匹配，这也证明了量子波函数在逆史密斯-珀塞尔效应中的作用。我们利用超快透射电子显微镜 (UTM) 的功能来维持由硅光子纳米光栅 DLA 介导的长达数百个激光脉冲周期的长电子-光相互作用长度。UTEM 被展示为表征未来 DLA 概念的新平台。结果提出了关于量子力学在 DLA 设计中的作用的基本问题，更普遍的是关于在加速器物理学中操纵粒子量子波函数的前景。