Bonn 2025 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MO: Fachverband Molekülphysik
MO 15: Interaction with VUV and X-ray Light I (joint session A/MO)
MO 15.3: Vortrag
Mittwoch, 12. März 2025, 11:30–11:45, GrHS Mathe
Exceptional points at x-ray wavelengths — •Fabian Richter1, Lars Bocklage2, Ralf Röhlsberger2, Xiangjin Kong3, and Adriana Pálffy1 — 1Julius-Maximilians-Universität Würzburg — 2Deutsches Elektronen Synchrotron DESY, Hamburg — 3Fudan University, Shanghai
Non-Hermitian Hamiltonians effectively describe dissipative systems, exhibiting phenomena absent in the Hermitian realm. Exceptional Points (EPs) are a prime example of this. At EPs not only the complex eigenvalues, but also the eigenvectors coalesce and sensitivity to perturbations is drastically enhanced. This concept has recently advanced in optics, where non-Hermitian eigenstates arise through optical gain and loss [1]. So far, these concepts have been mostly discussed in the optical regime. Similar control of x-rays is desirable due to their superior penetration power, high focusability and detection efficiency.
Here, we investigate non-Hermitian x-ray photonics in thin-film cav- ities with Mössbauer nuclei under grazing-incidence x-ray radiation. These cavities present loss that can be controlled via adjustment of the cavity geometry and the incidence angle of the x-rays [2]. The application of a magnetic hyperfine field enables tuning the system towards EPs. We theoretically determine the magnetic field strength at which an EP occurs and predict qualitatively distinct behavior in the time spectrum at higher and lower field strengths. Analysis of experimental data confirms these predictions.
[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