Speaker
Description
The coherent interaction of optical fields with electron beams underpins key developments in ultrafast electron microscopy and free-electron quantum optics. However, direct coupling between light and free electrons is prohibited in free space by energy–momentum conservation. Here, we overcome this limitation by using longitudinally polarized optical fields at a thin membrane, where the resulting focal fields enable direct, linear, and coherent modulation of an electron beam without the need for nanostructured coupling elements or non-collinear geometries. We further exploit vectorial polarizations to selectively excite and map three-dimensional nanophotonic near-fields in metallic mesocrystals via coherent electron energy gain and loss. Longitudinal electric fields are found to couple directly to axial near-fields, while longitudinal magnetic fields induce oscillatory ring currents through associated azimuthal electric fields. Our approach provides a general, collinear platform for attosecond electron-beam shaping, free-electron qubit generation, and multidimensional near-field imaging in ultrafast electron microscopy.
https://arxiv.org/abs/2605.22152