Hannover 2016 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 64: Nano-Optics III

Q 64.4: Talk

Friday, March 4, 2016, 11:45–12:00, f342

Quantum coherent Ramsey-type interactions of free electrons with spatially separated near-fields — •Katharina E. Echternkamp, Armin Feist, Sascha Schäfer, and Claus Ropers — 4th Physical Institute, University of Göttingen, Göttingen, Germany

A few years ago, inelastic interactions of free electrons with optical near-fields, i.e., the absorption and emission of multiple photons, were observed for the first time [1]. Recently, we experimentally demonstrated the quantum coherent nature of this interaction by measuring multilevel Rabi oscillations in the sideband populations of the electron energy spectra [2].

Here, we employ an ultrafast transmission electron microscope (UTEM) to realize a novel type of electron-light interferometer, in which free electron momentum superposition states are manipulated in a quantum coherent manner by two spatially separated optical near-fields. In the experiments, the electron beam passes a specially designed gold nanostructure, which enables precise amplitude and phase control of the two subsequent interactions. In some analogy to the Ramsey method of separated oscillatory fields [3], the relative phase between these interactions governs the total transition amplitude.

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

[2] A. Feist et al., Nature, 521,200-203 (2015).

[3] N. F. Ramsey, Rev. Mod. Phys. 62 (3), 541-552 (1990).