0_5333 Neutral atoms at ultralow temperatures are ideal candidates for quantum simulations, as they allow experimentalists to accurately investigate the relation between the properties of a quantum many-body system and the interactions between its constituents. Use of fermionic species could allow for quantum simulation of highly correlated fermionic matter, addressing paradigmatic phenomena such as exotic superfluidity and itinerant ferromagnetism. This quantum simulator must be built from the ground-up by exploiting the most favorable atomic mixture and carefully harnessing the underlying few-body physics. However, such a platform has not been experimentally realized yet. In our laboratory, we exploit a Fermi-Fermi mixture of 53Cr and 6Li, which, thanks to a mass ratio of M/m=8.8, is predicted to feature unique few-body properties and foster the many-body phases of our interest. We outline the few-body physics scenario and explain how this could enable the realization of a quantum simulator with unequal-mass spin-1/2 fermions with long-range, multi-body resonant interactions.  We report on the experimental investigation of the few-body properties of the Li-Cr system with our novel double-degenerate Fermi mixtures. Prior to our studies, even the two-body collisional properties of this system were unknown. After performing extensive Feshbach spectroscopy and in collaboration with Prof. A. Simoni (Univ Rennes), we developed an accurate and complete quantum collisional model at the two-body level. Leveraging on this understanding, we identify a set of strong s-wave resonances, essentially immune to two-body inelastic losses, and we experimentally characterize them, finding good agreement with the theoretical model. We show how we can exploit one such resonance to efficiently magneto-associate atom pairs into ultracold bosonic Feshbach dimers and study their stability and collisional properties. Furthermore, we present our measurements of the three-body inelastic loss rates in our system and discuss the results. We finally assess the implications of our findings with respect to quantum simulations and give an outlook for future experiments.