Düsseldorf 2007 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

A: Fachverband Atomphysik

A 15: Atomic Systems in External Fields I

A 15.3: Vortrag

Mittwoch, 21. März 2007, 12:00–12:15, 5M

First verification of exceptional points in the spectra of atoms in external fields — •Holger Cartarius, Jörg Main, and Günter Wunner — 1. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart

A degeneracy of two complex eigenvalues which has the form of a branch point singularity in systems which depend on a parameter is called an exceptional point. Exceptional points can appear in open quantum systems with resonances, which can be described by complex energy eigenvalues of non-Hermitian Hamiltonians. They have already been studied in a variety of systems, e.g., the laser induced ionization of atoms, acoustical systems, microwave cavities, and atom waves in optical lattices. However, an investigation of the spectra of atoms in external fields with respect to the presence of exceptional points is still lacking.

We report the first observation of exceptional points in the spectrum of the hydrogen atom in static external fields with numerical calculations. For that purpose, we investigate the resonances of the hydrogen atom in crossed electric and magnetic fields and show how exceptional points can be found by exploiting characteristic properties of the branch point singularities. We propose a method to extract resonances from experimental photoionization spectra and to verify the existence of exceptional points experimentally.