Optical runaway evaporation for multi-BEC production

Abstract: We report on parallel production of Bose-Einstein condensates (BECs) in steerable, multi-plexed crossed optical dipole traps. Using a conventional trap-weakening evaporation scheme, where the optical trapping power is lowered, we obtain an array of up to four independent BECs. To improve evaporation efficiency, we propose to target each crossed trap site with a narrow auxiliary laser beam, creating an escape channel for energetic atoms. We experimentally demonstrate runaway evaporation using this scheme, which is characterized by very modest weakening in atomic confinement such that high densities and elastic collision rates can be maintained. Based on discretely time-shared optical tweezers, our approach is particularly suited for addressing the problem of simultaneously cooling atoms in multiple traps clouds, providing the freedom to act locally and in a tailored fashion at individual trap sites.