Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 70: Structural Dynamics in Nanoscale Materials Probed by Ultrashort Electron Pulses

O 70.7: Poster

Mittwoch, 18. März 2015, 18:15–21:00, Poster A

Quantum coherent interaction of electrons with optical near-fields in an ultrafast electron microscope — Armin Feist, •Katharina E. Echternkamp, Jakob Schauss, Sergey V. Yalunin, Sascha Schäfer, and Claus Ropers — 4th Physical Institute, University of Göttingen, Göttingen, Germany

Harnessing the coherent interaction of light and matter is expected to play a key role for future quantum computation, communication and metrology. Here, we present the coherent quantum state manipulation of free electrons in an ultrafast electron microscope [1]. Ultrafast transmission electron microscopy (UTEM) is a laser pump/electron probe technique, enabling the investigation of ultrafast processes on the nanometer length scale [2]. We have recently implemented an UTEM by modifying a commercial Schottky field emission TEM (JEOL JEM-2100F). In our experiments, the electron beam is focused to a spot close to a surface of a conical gold tip. The high spatial confinement of the optically excited near-field of the nanostructure allows for an otherwise forbidden dipolar coupling between the free electrons and photons. In the electron kinetic energy spectra, we observe the creation of spectral sidebands, stemming from the absorption and emission of multiple photons [3]. The field dependent sideband populations reveal the quantum coherence of the process.

[1] A. Feist et al., submitted (2014).

[2] A.H. Zewail, Science, 328, 187 (2010).

[3] B. Barwick et al., Nature, 462,902 (2009).