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We report on the production of a 41K−87Rb dual-species Bose-Einstein condensate in a hybrid trap, consisting of a magnetic quadrupole and an optical dipole potential. After loading both atomic species in the trap, we cool down 87Rb first by magnetic and then by optical evaporation, while 41K is sympathetically cooled by elastic collisions with 87Rb. We eventually produce two-component condensates with more than 105 atoms and tunable species population imbalance. We observe the immiscibility of the quantum mixture by measuring the density profile of each species after releasing them from the trap. A. Burchianti, et al. |
Considering the hurdles of experiments with more than one atomic species, the temptation arises of rephrasing Arthur L. Schawlow: "Double-species Bose-Einstein condensates are condensates with one species too many". We think otherwise. Quantum mixtures allow the investigation of a wealth of genuinely quantum phenomena: mixed phases of superfluids and Mott insulators, impurities and polarons, chemistry at zero-temperature.