The aim of this internship is the implementation of "Delta-Kick squeezing" in a differential atom interferometer. DKS relies on the engineering of atom atom interactions in a BEC in free fall through atomic lensing methods based on pulse sequences realized with highly detuned high power laser beams. The focusing of the matter waves transiently increases the strength of the interactions, which induces strong correlations between the atoms, and leads to squeezing in the population difference between the two interferometer paths, and eventually to phase sensitivity below the standard quantum limit.