After more than 20 years of fundamental research, atom interferometers have reached sensitivity and accuracy levels competing with or beating inertial sensors based on different technologies. Atom interferometers offer interesting applications in geophysics, inertial sensing, metrology and tests of fundamental physics. Recently, a growing interest of the application of atom interferometry to gravitational wave detection and geophysics has been drawn. These applications beyond the pure scope of atomic physics require the development of more performant atomic inertial sensors, particularly for the use of matter-wave interferometers in gravitational wave detectors, where sensitivity levels far beyond the state of the art must be demonstrated. The proposed project aims at contributing filling this gap by studying new atom and optical interferometry techniques, in order to significantly improve the performances of matter-wave gravitation sensors. The proposed MSC action will significantly impact the design of a new class of matter-wave gravitation sensors, which are under study in several countries in the world. In the excellence metrology environment of SYRTE, the MSC applicant will foster challenging developments in atom interferometers, with a high impact on the communities of atomic physics, geophysics and gravitational wave detection. On this path, the Experienced Researcher will benefit from an original and efficient training by the host group through knowledge transfer, acquisition of new scientific and management skills, enlargement of her professional network and development of her track record.