Speaker
Description
The controlled shaping of free-electron wavepackets using optical near-fields is emerging as a powerful tool for ultrafast electron science, with applications ranging from attosecond electron pulse generation to strong-field electron microscopy [1]. In photon-induced near-field electron microscopy (PINEM), a swift electron exchanges discrete quanta of photon energy with an optical near-field, producing a ladder of energy sidebands whose amplitudes and phases encode the electron–light interaction. Extending this concept to multiple PINEM interactions offers a route to full electron-wavefunction control: sequential or parallel optical near-fields can act as programmable elements that shape the longitudinal phase and amplitude of the electron wavepacket.
Here, we investigate coherent and incoherent multi-PINEM regimes using a consistent wavepacket-propagation model. In the coherent case, multiple interactions share well-defined optical phase relations, leading to interference between sideband pathways and strong phase-dependent control over the temporal electron density. This enables tunable temporal focusing, attosecond pulse formation, and the possibility of generating multiple sub-cycle electron pulses within one optical period. In contrast, when the PINEM interactions are mutually incoherent, the final spectrum is described by a probabilistic convolution of the individual sideband distributions, removing phase-sensitive interference and strongly reducing temporal tunability.
Our results establish multi-stage PINEM as a versatile platform for optically driven electron-waveform synthesis. By comparing coherent and incoherent interaction pathways, we identify the conditions under which spatially separated, sequential, or parallel near-field interactions can be used to engineer the electron wavefunction on demand. This framework provides design principles for attosecond electron sources and for future experiments exploring light–electron coherence and ultrafast electron dynamics.
Reference
[1] A. Feist, K. E. Echternkamp, J. Schauss, S. V. Yalunin, S. Schäfer, and C. Ropers, Nature 521, 200–203 (2015).