Speaker
Description
While the spatial structuring of free electrons plays a crucial role in nanoscale photonics, their interactions are conventionally modeled within semiclassical approximation. Here, we develop a full quantum description of a free electron interacting with a vortex near field. With the quantized theory, we show that the interaction can generate high-dimensional entanglement involving the electron energy and orbital angular momentum (OAM).
Vacuum fluctuations alone produce spontaneous electron–plasmon entanglement with OAM-resolved correlations. Strikingly, under intense coherent-state vortex driving, the free-electron state evolves into a quantum coherent "OAM comb" extending across over a hundred modes. This state is endowed with intraparticle energy–OAM entanglement reaching an effective dimensionality of ~20, while retaining the information about the underlying photon statistics.
This expansive spatial–spectral structure realizes the quantum-structured free electron, establishing it as a novel flying qudit that offers a multidimensional resource for advanced quantum information processing, ranging from topologically protected on-chip quantum logic gates to secure communication protocols. Additionally, this approach holds great potential for dynamically resolving atomic-scale magnetic and chiral phenomena through dichroic spectroscopy and advancing ultrafast quantum electron microscopy.