Seminars Archive

Spatio-temporal coherent control of an electron wavefunction via semi-infinite and localized electromagnetic fields

Abstract
The interaction between light and charged particles can be exploited for generating radiation, such as in synchrotrons and free electron lasers, or for controlling electron beams in applications such as time-resolved electron microscopy. The coherent control of free electrons by electromagnetic fields, which would enable new applications in quantum devices and attosecond electron sources, requires manipulating and mapping a free electron's wavefunction. In this contribution, I will report on a generalized method for the coherent manipulation of free electrons with attosecond precision using an ultrafast transmission electron microscope [1-3]. A relativistic pulsed electron beam was made to interact with an appropriately synthesized electromagnetic field. The field was generated either by a sequence of two fs laser pulses reflected at the surface of a mirror (semi-infinite field), or by the coherent superposition of the surface plasmon polaritons optically-generated from nanofabricated structures (localized field). The energy-momentum exchange resulting from the electron-field interaction was directly mapped via fs-momentum resolved electron energy loss spectroscopy. When the two phase-locked light pulses were delayed by fractions of the optical cycle (sub-fs), we observed the coherent oscillations in the electrons energy-momentum states and their phase. This effect is the result of a coherent constructive and destructive phase modulation of the electron wavefunction while varying the relative phase between the two driving optical pulses. The method developed here is very general and can be extended to the case of free electrons interacting with photons of any energy, allowing the coherent control of their wavefunction in the attosecond and even zeptosecond time-scale.

References
[1] G.M. Vanacore, et al., Nano Today 11, 228-249 (2016)
[2] L. Piazza, et al., Nat. Commun. 6, 6407 (2015)
[3] T.T.A. Lummen, et al., Nat. Commun. 7, 13156 (2016)