The aim is to develop consistent approximation methods which can be systematically refined and which allow to take into account quantum fluctuations. We use quantum field theory methods from mathematical physics and combine them with more conventional solid state physics methods. Results include no-go theorems on the the existence of reduced dynamics of open quantum systems as an exact description of the quantum correlation functions. There is also a characterization of determinism versus randomness of the correlation functions using spectral properties or entropy measures of information. Possible applications include quantum information transmission and computation.
Neutrino oscillations can occur if neutrinos have masses that are nonzero and different.
In the Standard Model of elementary particles this cannot take place. Evidence for neutrino oscillations is therefore an indication of New Physics beyond the Standard Model. In the early summer of '98 the Super-Kamiokande collaboration reported evidence for neutrino oscillations related to the atmospheric neutrino problem. This has rekindled an interest to interpret all deviations from expected results in neutrino physics in terms of neutrino oscillations. We are working on several problems in the realm of neutrino oscillations.