Theoretical seminar | 02 April 2025

Non-Hermitian singularities – exceptional points (EPs), bulk Fermi arcs, Rayleigh anomalies, and bound states in the continuum (BICs) – exhibit unique wave phenomena with transformative potential in photonics [1,2]. While EPs enable extreme sensitivity, Fermi arcs bridge Hermitian and non-Hermitian topology, and BICs offer infinite radiative quality factors. Here, we theoretically and experimentally investigate these singularities within isolated dielectric and periodic metastructures. Specifically, we predict exceptional BIC (EP-BIC) states in vertically coupled dielectric metasurfaces [3], experimentally demonstrate bulk Fermi arcs in single dielectric resonators [4], and explore the previously unstudied link between EPs and anapole states [5].

Main paper/arXiv, related to the seminar, and other references

[1] E. J. Bergholtz et al., Rev. Mod. Phys. 93, 015005 (2021).
[2] H. Zhou et al., Science 359, 1009 (2018).
[3] A. Canós Valero et al., Phys. Rev. Lett. (in press, 2025).
[4] N. Solodovchenko et al., arXiv:2502.12711 (2025).
[5] F. Zhang et al., Sci. Adv. 11, eadr9183 (2025).