Hartmut Abele at TU Wien has wide experience in high precision experimentation using thermal, cold and ultra-cold neutrons. The neutrons are investigated both in-beam, or confined in traps, with the aim to test fundamental interactions and symmetries. The current research focus is on the relationship between gravitation and quantum mechanics. As the pioneer in the field, the Vienna group is able to drive resonant transitions between quantum states in the gravity potential of the earth. By implementing this gravitational resonant spectroscopy technique to measure the discrete energy eigenstates of a bouncing quantum particle, the method provides a constraint on any possible hypothetical gravity-like interactions on that level of accuracy, which allows to confront theory with precision measurements.