Observation of superradiance in a dipolar Bose-Einstein condensate of ¹⁶⁸Er atoms

Matter-wave superradiance, a cooperative emission process providing directional scattered atom clouds, has been studied in various systems ranging from weakly interacting Bose-Einstein condensates and free fermions to degenerate quantum gases coupled to the cavity mode. To date, however, most experiments have explored superradiance with closed-shell atoms (e.g. alkali and alkaline-earth-like atoms) in the regime where only s-wave interactions are present. Here, we experimentally examine a superradiance phenomenon in an interacting dipolar Bose gas of ¹⁶⁸Er atoms. By tuning s-wave interaction strength through the Feshbach resonance, we explore how the interplay between s-wave and dipolar interactions affects superradiance processes. A detailed analysis of the superradiance process when the external magnetic field breaks the symmetry will be presented. Furthermore, we disscuss the suppression of the superradiance due to the occurrence of the phase fluctuation.