Experiments with rubidium Bose-Einstein condensates in a radio-frequency field: Interactions, collisions and interference

The field of precision spectroscopy and metrology was revolutioned by the introduction of lasers as coherent sources of photons. Furthermore; laser cooling techniques, based on the interaction between photons and atoms, allow the manipulation of atoms providing samples at very low temperatures. Coherent electro-magnetic fields and cold atomic samples today are fundamental to metrology. Bose-Einstein condensation (BEC) offers a unique sample of coherent matter [1] at ultralow temperatures, which is likely to open new important perspectives also for metrology. Thus, understanding the different aspects of how BECs interact and interfere among themselves goes into the direction of using sample of condensed atones for precise measurements. In the present work we illustrate rich new phenomenology provided by experiments with overlapping or colliding multicondensates. We show how interactions can be evidenced through precise frequency measurements and also quantitatively discuss the effect of gravity on time domain interferometry with condensates.