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A: Fachverband Atomphysik
A 32: Interaction with VUV and X-ray Light I (joint session A/MO)
A 32.2: Vortrag
Donnerstag, 5. März 2026, 15:00–15:15, N 2
Non-Hermitian X-Ray photonics and Exceptional Points in thin-film cavities with Mössbauer nuclei — •Fabian Richter1, Lars Bocklage2, Sven Velten2, Ralf Röhlsberger2, Xiangjin Kong3, and Adriana Pálffy1 — 1Julius-Maximilians-Universität, Würzburg — 2DESY, Hamburg — 3Fudan University, Shanghai
Exceptional Points (EPs) mark non-Hermitian degeneracies where eigenvalues and eigenvectors coalesce, producing enhanced sensitivity to perturbations. While widely explored in optical gain-loss systems [1], translating the physics of EPs to the X-ray regime offers distinct advantages such as superior penetration depth, focusability, and detection efficiency.
Here, we investigate non-Hermitian X-ray photonics in thin-film cavities with 119Sn Mössbauer nuclei under grazing-incidence illumination. In addition to theoretical modeling, we analyze experimental time spectra and reflectivity data recorded at PETRA III. The cavity geometry and incidence angle offer tunable control over dissipation [2], while a magnetic hyperfine field enables steering the system toward EPs. In theory, we identify the magnetic field strengths at which EPs emerge and predict qualitatively distinct features in the simulated time spectra. In the experimental time spectra, the situation is more complicated, especially as quadrupole splitting introduces additional spectral structure and increases the complexity of the eigenvalue problem, yet we are able to reliably extract the relevant signatures.
[1] L. Feng et al., Nature Photon. 11, 752-762 (2017).
[2] J. Evers, K. P. Heeg, Phys. Rev. A 88, 043828 (2013).
Keywords: X-ray Quantum Optics; Non-Hermitian Physics; Thin-Film Cavity