title: Exceptional points in atomic spectra.
abstract: We report the existence of exceptional points for the hydrogen atom in crossed magnetic and electric fields in numerical calculations. The resonances of the system are investigated and it is shown how exceptional points can be found by exploiting characteristic properties of the degeneracies, which are branch point singularities. A possibility for the observation of exceptional points in an experiment with atoms is proposed.
authors.affiliation: Institut für Theoretische Physik 1, Universität Stuttgart, 70550 Stuttgart, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Cartarius
authors.forename: Jörg
authors.initials: J
authors.lastname: Main
authors.forename: Günter
authors.initials: G
authors.lastname: Wunner