The temperature can be further reduced through evaporative cooling of the magnetically trapped neutral atoms, and for bosonic species the dilute gas can eventually undergo Bose-Einstein condensation as the ground state becomes occupied by a substantial fraction of the atoms. With all its atoms in the same quantum state, a Bose-Einstein condensate (BEC) after release from the trap is the atomic analogue of a laser pulse, where all the photons are also in the same state. Thanks to that BECs exhibit excellent coherence properties and a narrow momentum distribution. However, the energy associated with the repulsive interaction between the atoms, which is typically the dominant contribution for trapped BECs, is converted into kinetic energy after being released from the trap and additional techniques, such as atomic lensing (briefly described below), need to be employed in order to attain particularly low expansion rates (i.e. low momentum widths of the atomic wave packet).
Besides the atom interferometry aspects, discussed here, in our group we have been developing suitable analytical and numerical tools for investigating (among others) the following topics.
 Van Zoest et al. (the QUANTUS collaboration), Bose-Einstein Condensation in Microgravity, Science 328, 1540 (2010)
 Müntinga et al. (the QUANTUS collaboration), Interferometry with Bose-Einstein condensates in microgravity, Phys. Rev. Lett. 110, 093602 (2013)
 Aguilera et al. (the STE-QUEST consortium, including A. Roura and W. P. Schleich), STE-QUEST – Test of the Universality of Free Fall Using Cold Atom Interferometry, Class. Quant. Grav. 31, 115010 (2014)
 H. Ahlers, H. Müntinga, A. Wenzlawski, M. Krutzik, G. Tackmann, S. Abend, N. Gaaloul, E. Giese, A. Roura, R. Kuhl, C. Lämmerzahl, A. Peters, P. Windpassinger, K. Sengstock, W. P. Schleich, W. Ertmer, E. M. Rasel, Double Bragg interferometry, Phys. Rev. Lett. 116, 173601 (2016)
 C. Ufrecht, M. Meister, A. Roura, W. P. Schleich, Comprehensive classification for Bose–Fermi mixtures, New J. Phys. 19, 085001 (2017)
 D. Becker et al. (the MAIUS team), Space-borne Bose–Einstein condensation for precision interferometry, Nature 562, 391 (2018)
 M. Meister, A. Roura, E. M. Rasel, W. P. Schleich, The space atom laser: An isotropic source for ultra-cold atoms in microgravity, New J. Phys. 21, 013039 (2019)