The proposed project deals with high-resolution measurements of the lifetime of magnetic excitations in simple (quantum) magnets and of lattice vibrations (phonons) in the nominally well-understood simple-metal superconductors. The results will be compared with model calculations, which are density functional theory (DFT) calculations for phonons, and concepts beyond linear spin wave theory for quantum magnets. The results will be essential for the understanding of basic notions in quantum effects in magnetism, as well as in the foundations of superconductivity in simple metals.