Tunable photon-induced spatial modulation of free electrons

Spatial modulation of electron beams is an essential tool for various applications such as nanolithography and imaging1–3 , yet its implementations4–11 are severely limited and inherently non-tunable. Conversely, light-driven electron spatial modulation12–15 could potentially allow arbitrary electron wavefront shaping16–18 via the underlying mechanism of photon-induced nearfield electron microscopy (PINEM)19–21 . Here, we present tunable photon-induced spatial modulation of electrons through their externally-controlled interaction with surface plasmon polaritons (SPPs). Using recently developed methods of shaping SPP patterns 22,23, we demonstrate a dynamic control of the electron beam with a variety of high-quality electron distributions. Intriguingly, by utilizing the intrinsic interaction nonlinearity24, we attain the first observation of 2D spatial Rabi oscillations25,26 and generate electron features below the SPP wavelength. Our work paves the way to on-demand electron wavefront shaping at ultrafast timescales, with prospects for aberration correction, nano-fabrication and material characterization.