Despite the tremendous success of the Standard Model of particle physics, there remain several fundamental aspects of the Universe that are still not understood. One such is the violation of the symmetry of simultaneous charge exchange and parity inversion (CP), which allowed the early Universe to become more abundant in matter than in antimatter. For some 65 years the electric dipole moment of the neutron (nEDM) has been the observable of choice to gain insight into this problem.

At the Paul Scherrer Institute in Switzerland our collaboration is currently running the world's most sensitive nEDM measurement. Our goal is to explore the area below the present limit of the nEDM, which stands at 3e-26 ecm 90% C.L. [J.M. Pendlebury et al. PRD 92, 092003 (2015)]. In my talk I will explain how we measure the nEDM using Ramsey interferometry of neutrons. Operating at neV energies, we employ an exciting combination of the gravitational, strong and electromagnetic interactions to guide, store and manipulate the spins of polarised ultra-cold neutrons. The measurement requires magnetic field stabilities on a picotesla level, reaching of which is only possible thanks to an active magnetic field compensation system. Ongoing R&D effort for a next generation compensation system is going to be presented. I will also discuss how our experiment is used to explore alternative extensions to the Standard Model, such as for example an ultra-low-mass axion dark-matter search.