Graduation research topic by supervision of Sven Ahrens
at Shanghai Normal University
Graduate student research topic
(Master student graduation topic)
Colliding laser beam approximation investigation
We model quantum dynamics of electrons in strong laser fields in the context of Einstein's theory of special relativity [1]. For that we solve the relativistic quantum wave equation for spin 1/2 particles: The Dirac equation. The Dirac equation has interesting features. It has the electron spin degree of freedom already intrinsically included and since it also allows for negative energy solutions, it is deeply connected to anti-matter and related topics. We commonly simulate electron diffraction in colliding laser beams [2,3], which is an effect which is usually termed "the Kapitza-Dirac effect". Often, the computation of this simulation assumes plane, infinitely extended laser beams. In the intended research project we want to investigate, how well this approximation works, with a more general solution technique for solving the Dirac equation [4]. Interesting and related questions are connected to this project, like for example the radiation generated by an electron in such an external laser field. Computer codes are readily available in C++ and Python, which are the main tool which we use in the workgroup, in a Linux based computation environment.
[1] S. Ahrens, H. Bauke, C. H. Keitel, and C. Müller, Spin Dynamics in the Kapitza-Dirac Effect, Phys. Rev. Lett. 109, 043601 (2012) / arXiv:1204.0239
[2] S. Ahrens, H. Bauke, C. H. Keitel, and C. Müller, Kapitza-Dirac effect in the relativistic regime, Phys. Rev. A 88, 012115 (2013) / arXiv:1305.5507
[3] S. Ahrens, Z. Liang, T. Čadež, and B. Shen, Spin-dependent two-photon Bragg scattering in the Kapitza-Dirac effect, Phys. Rev. A 102, 033106 (2020) / arXiv:2001.10177
[4] P. Ge, S. Ahrens, and B. Shen, Two-dimensional simulation of the spin flip in the kapitza-dirac effect, Phys. Rev. A 109, 022240 (2024) / arXiv:2307.01571
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