Frankfurt 2006 – scientific programme

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A: Atomphysik

A 12: Atomare Systeme in externen Feldern I

A 12.7: Talk

Wednesday, March 15, 2006, 15:45–16:00, H6

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

The coalescence of two complex eigenvalues in systems which depend on a parameter is called an exceptional point. Exceptional points can appear in open quantum systems with decaying unbound states which have complex energies and are described by a non-Hermitian Hamiltonian. They have been observed in the laser induced ionization of atoms, acoustical systems, microwave cavities, and atom waves in optical lattices. However, no exceptional points have been discovered in atoms in static external fields yet.

We search for exceptional points in the spectrum of the hydrogen atom in crossed electric and magnetic fields at energies above the ionization threshold. This is a fundamental physical system which fulfills the conditions for a coalescence of two eigenvalues in the complex plane. The calculation of the eigenvalues requires the diagonalization of large complex symmetric matrices.