Spatio-temporal shaping of electron wavepackets for time-domain electron holography

Introduction

Advanced techniques of electron microscopy and spectroscopy require tools that enable control over various degrees of freedom of electron beams, such as phase profile, temporal structure, and orbital angular momentum. The inelastic quantum coherent interaction between light waves and electron wavepackets allows for the structuring of the temporal probability distribution of electrons with attosecond precision. This capability may enable probing the coherent dynamics of optical excitations or plasmonic near-fields of nanostructures and metamaterials.

Limitations of Current Methods

Up to now, only electron-photon interactions mediated by solid-state structures have been considered, which have severe limitations.

Project Objectives

In this project, I will develop a versatile tool for quantum coherent shaping and full characterization of the phase profile and amplitude of the electron wave function in electron microscopes. The interaction will be mediated by the ponderomotive potential of spatio-temporally shaped light fields in vacuum.

Control of Electron Wavepackets

The electron wavepackets will be controlled on nanometer spatial and sub-femtosecond time scales that are natural for light waves. The optical coherence imprinted onto the electron wavepackets will be exploited in two ways:

1. I will explore the possibility of transferring the temporal coherence from density-modulated electron wavepackets to radiation and bound electron excitations in two-level quantum systems by detecting phase-resolved cathodoluminescence and coherent Smith-Purcell radiation driven by swift electrons.
2. I will introduce time-domain electron holography, which will exploit the temporal coherence of shaped electron wavepackets for phase-resolved imaging of optical excitations in nanostructures.

Conclusion

The approaches proposed in this project open new pathways for electron-mediated optical quantum-coherent control and spectroscopy with atomic spatial resolution.