“…To put this development in context, we note here recent progress in the experimental processing of data and control and manipulation of ultracold atoms in colliding free-space beams or clouds (including free fall under the cloud's gravity) [10,11,23,25,[31][32][33] or in optical traps and tweezers (in situ or TOF) [34][35][36][37], which has motivated a growing number of both experimental [10,11,23,[31][32][33][34][35][36][37] and theoretical [12-15, 38, 39] studies concerning the analogies between quantum optics and matter-wave spectroscopy.…”