Deconfinement-induced collapse of a coherent array of dipolar Bose-Einstein condensates

We report on the observation of the collapse of a dipolar Bose-Einstein condensate (BEC) upon release from a one-dimensional optical lattice. In strong contrast with the typical behavior of quantum gases under time of flight (TOF), we show here that a strongly dipolar BEC, stabilized in the lattice, may become unstable during the TOF dynamics due to the combined effect of the anisotropy of the dipolar interaction and intersite coherence. Such TOF-triggered collapse is a peculiar case of a collapse induced by the deconfinement of a dipolar many-body system at a fixed two-body interaction strength.