2009/02/27 by Holger Cartarius, Jörg Main, Günter Wunner · 2 citations
Physics and Astronomy · #Quantum Mechanics and Non-Hermitian Physics #Quantum chaos and dynamical systems #Quantum optics and atomic interactions #nlin.CD #physics.atom-ph
paper · pdf · doi:10.1103/physreva.79.053408
published as Phys. Rev. A 79, 053408 (2009) · 12 pages, 9 figures, 1 table
arxiv created 2009/02/27 · openalex publication_date 2009/05/12 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We investigate exceptional points, which are branch-point singularities of two resonance eigenstates, in spectra of the hydrogen atom in crossed external electric and magnetic fields. A procedure to systematically search for exceptional points is presented, and their existence is proven. The properties of the branch-point singularities are discussed with effective low-dimensional matrix models, their relation with avoided level crossings is analyzed, and their influence on dipole matrix elements and the photoionization cross section is investigated. Furthermore, the rare case of a connection between three resonances almost forming a triple degeneracy in the form of a cubic-root branch point is discussed.