Description
The computation of quantum effects in laser fields is often based on the assumption of a plane wave approach [1]. This is also the case for the Kapitza-Dirac effect [2-4], which is the diffraction of electrons at a standing light wave. The effect is interesting because it allows for the detection of the spin of an electron which is moving freely in space [5]. For this case of the Kapitza-Dirac effect, the question arises, whether beam focusing is influencing the predicted spin effects [6].
In our contribution we discuss a numeric study of the Kapitza-Dirac effect spin dynamics in a Gaussian laser beam [7]. Within the frame work of a non-perturbative FFT-split operator method [7,8] we are able to model the relativistic quantum dynamics (Dirac equation) of the electron such that virtually no approximations are made in the calculation. With the simulation we can demonstrate the theoretical existence of a spin-flip in the Kapitza-Dirac effect for a wave function in two dimensions. We further discuss the dependence of the effect regarding beam focusing and laser frequency in the hard x-ray regime. Also dynamics beyond the perturbatively well described 2-photon Kapitza-Dirac [4,5] effect are presented.
References:
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5. S. Ahrens, Z. Liang, T. Čadež, and B. Shen, Phys. Rev. A 102, 033106 (2020).
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