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arXiv · 2404.00304

Ultrafast Kapitza-Dirac effect

Kang Lin·Sebastian Eckart·Hao Liang·Alexander Hartung·Sina Jacob·Qinying Ji·Lothar Ph. H. Schmidt·Markus S. Schöffler·Till Jahnke·Maksim Kunitski·Reinhard Dörner
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Abstract

Similar to the optical diffraction of light passing through a material grating, the Kapitza-Dirac effect occurs when an electron is diffracted by a standing light wave. In its original description the effect is time-independent. In the present work, we extend the Kapitza-Dirac concept to the time domain. By tracking the spatiotemporal evolution of a pulsed electron wave packet diffracted by a femtosecond (10 15 second) standing wave pulse in a pump-probe scheme, we observe so far unseen time-dependent diffraction patterns. The fringe spacing in the observed pattern differs from that generated by the conventional Kapitza-Dirac effect, moreover it decreases as the pump-probe delay time increases. By exploiting this time-resolved diffraction scheme, we gather access to the time evolution of the previously inaccessible phase properties of a free electron.

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Kang Lin, Sebastian Eckart, Hao Liang, Alexander Hartung, Sina Jacob, Qinying Ji, Lothar Ph. H. Schmidt, Markus S. Schöffler, Till Jahnke, Maksim Kunitski, Reinhard Dörner. 2024-03-30. Ultrafast Kapitza-Dirac effect. https://doi.org/10.1126/science.adn1555

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