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DY: Fachverband Dynamik und Statistische Physik

DY 47: Quantum Chaos and Coherent Dynamics (joint session DY/TT)

DY 47.6: Talk

Thursday, March 21, 2024, 16:30–16:45, A 151

Higher-order exceptional points in waveguide-coupled microcavities — •Julius Kullig¹, Daniel Grom¹, Sebastian Klembt², and Jan Wiersig¹ — ¹Institut für Physik, Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany — ²Physikalisches Institut and Wilhelm-Conrad-Röntgen-Research Center for Complex Material Systems, University of Würzburg, Würzburg, Germany

Open quantum and wave systems exhibit fascinating and exotic behavior described by non-Hermitian physics. A key feature of such systems are exceptional points (EPs) in the parameter space. At these EPs the eigenvalues of the Hamiltonian become degenerate and simultaneously the corresponding eigenstates coalesce. Consequently, the system has interesting chiral eigenstates and is highly sensitive to external perturbations. A hot topic of current research is the creation of high-order EPs, where more than two eigenstates coalesce. In this talk, we present an intuitive and robust implementation of high-order EPs in photonic structures consisting of waveguide-coupled microring cavities. Combining the unidirectional coupling from the waveguide with mirror-induced asymmetric backscattering, we can increase the order of the EPs even further. Furthermore, we demonstrate that our setup allows for an easy realization of non-generic perturbation schemes.

Keywords: Optical Microcavities; Exceptional Points; Non-Hermitian Physics