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Humboldt-Universität zu Berlin - Faculty of Mathematics and Natural Sciences - Department of Physics

Humboldt-Universität zu Berlin | Faculty of Mathematics and Natural Sciences | Department of Physics | Colloquium | Colloquia | Department Colloquium: Prof. Dr. Claus Ropers (Universität Göttingen)

Department Colloquium: Prof. Dr. Claus Ropers (Universität Göttingen)

When Jan 24, 2017 from 03:15 to 05:00 (Europe/Berlin / UTC100) iCal
Where Lise-Meitner-Haus, Christian-Gerthsen-Hörsaal

Prof. Dr. Claus Ropers (Universität Göttingen) will speak about "Developments in Ultrafast Transmission Electron Microscopy".

Abstract: Ultrafast Transmission Electron Microscopy (UTEM) is an emerging technique to study structural and electronic dynamics on the nanoscale. Besides its use as an analytical tool with simultaneous femtosecond temporal and nanometer spatial resolution [1], UTEM also provides for a unique test bench to study quantum optics phenomena with free electrons.

This talk will discuss several examples of free-electron beams interacting with optical near-fields at nanostructures, emphasizing quantum coherent phenomena. Specifically, for swift electrons traversing intense optical near-fields [2, 3], we observe multilevel Rabi-oscillations on a ladder of quantized free-electron states [4], and implement Ramsey-type dual interactions in polarization-controlled, spatially separated near-fields [5]. Employing phase-locked two-color fields, coherent control of free-electron states is demonstrated [6]. We introduce a scheme to characterize the quantum state of such phase-modulated free-electron states in terms of their density matrix or Wigner function [6].

Finally, we demonstrate various new possibilities in the coherent manipulation of the longitudinal and transverse degrees of freedom of free-electron wave functions, including the optical preparation of attosecond electron pulses.

References

[1] A. Feist et al., "Ultrafast transmission electron microscopy using a laser-driven field emitter: Femtosecond resolution with a high coherence electron beam", Ultramicroscopy (in press, 2016), http://dx.doi.org/10.1016/j.ultramic.2016.12.005

[2] B. Barwick, D. J. Flannigan, and A. H. Zewail, "Photon-induced near-field electron microscopy", Nature 462, 902 (2009).

[3] F. J. García de Abajo, Ana Asenjo-Garcia and Mathieu Kociak, "Multiphoton absorption and emission by interaction of swift electrons with evanescent light fields", Nano Lett. 10, 1859 (2010).

[4] A. Feist, K. E. Echternkamp, J. Schauss, S. V. Yalunin, S. Schäfer, and C. Ropers, "Quantum coherent optical phase modulation in an ultrafast transmission electron microscope", Nature 521, 200 (2015).

[5] K. E. Echternkamp, A. Feist, S. Schäfer, and C. Ropers, "Ramsey-type phase control of free electron beams", Nature Phys. 12, 1000 (2016).

[6] K. E. Priebe et al., unpublished.