The sensitivity of many high-precision measurements based on atom interferometry benefits greatly from long interferometer times, which can be naturally achieved with compact set-ups in microgravity platforms such as drop towers, sounding rockets and dedicated space missions. This can be applied, for example, to atom-interferometry tests of the equivalence principle based on the differential measurement of the accelerations experienced by two atomic species. However, such long times pose a number of challenges associated with the growing size of the atomic cloud and with the unwanted effects of rotations and gravity gradients, some of which grow even cubically with time. After reviewing all these aspects, I will present recently developed techniques that can successfully tackle these difficulties and have already been demonstrated experimentally.

This work has been supported by the German Space Agency (DLR) with funds provided by the Federal Ministry of Economics and Energy (BMWi) under Grant No. 50WM1556 (QUANTUS IV).