Interferometry with expanding Bose-Einstein condensate in microgravity can be exploited to probe fundamental physics at the border between quantum mechanics and general relativity.
In particular millions of atoms in a BEC can be described by a single macroscopic wave function which o�ers itself for quantum interference experiments aimed to test the weak equivalence principle.
In this talk I will describe the physics behind the BEC expansion and interference in microgravity in the time-dependent Thomas-Fermi (TF) regime in generic interferometric congurations and taking into account rst order corrections in perturbation theory.
In particular, by using an asymmetric Mach-Zehender conguration interference fringes for expanding BEC in microgravity have been recently observed in pioneering experiments within our QUANTUS collaboration
. Such experiments not only represent a perfect test for future experiments in orbit but also gives us an important motivation in pursuing further exciting research based on quantum gravimeters for ground based applications.
 1. H. Muentinga, et al., Phys. Rev. Lett. 110, 093602 (2013) (Viewpoint: M. Arndt, Physics 6, 23 (2013)).