Oliver Siebert - Positive commutators in the context of thermal ionization

We consider an atom modeled as Schrödinger operator interacting with a quantized field at positive temperature. To prove eventual ionization of the atom it is sufficient to show the absence of eigenvalues of the operator describing the coupled system. This can be done using positive commutators in combination with a Virial theorem. In this talk I will sketch some techniques and elements of the proof.