Neutrons are particularly useful to study the evolution of a genuine spin-12 quantum system and its interaction with the environment. We report on the characteristics of a newly designed apparatus for storing ultra-cold neutrons (UCN) and manipulating their spin by means of a 3D Helmholtz-coil arrangement. In particular, using UCN requires homogeneous and stable magnetic fields across the storage volume in order to maintain a spin-superposition state for a sufficiently long time. Experimental results on the successful manipulation of the neutrons spin by means of Rabi oscillations and Ramsey interference fringes with a newly designed apparatus are presented. Coherence times exceeding 500ms make the apparatus suitable for further measurements on (de-)coherence and geometric phases.