Abstract
We report on the production of a 41 K- 87 Rb dual-species Bose–Einstein condensate with tunable interspecies interaction and we study the mixture in the attractive regime; i.e., for negative values of the interspecies scattering length a 12 . The binary condensate is prepared in the ground state and confined in a pure optical trap. We exploit Feshbach resonances for tuning the value of a 12 . After compensating the gravitational sag between the two species with a magnetic field gradient, we drive the mixture into the attractive regime. We let the system evolve both in free space and in an optical waveguide. In both geometries, for strong attractive interactions, we observe the formation of self-bound states, recognizable as quantum droplets. Our findings prove that robust, long-lived droplet states can be realized in attractive two-species mixtures, despite the two atomic components possibly experiencing different potentials.
Highlights
Ultracold atomic mixtures—formed by atoms of the same species in different spin states, or as different isotopes or elements—enable us to address a wide variety of problems in many-body physics
Within the MF theory, the binary gas is stable in the weakly attractive regime, while it is expected to become unstable beyond the critical value ac12
We have shown that robust and largely tunable binary condensates can be realized by exploiting two-species mixtures of 41K and 87Rb
Summary
Ultracold atomic mixtures—formed by atoms of the same species in different spin states, or as different isotopes or elements—enable us to address a wide variety of problems in many-body physics They have been largely used to investigate phase-transitions [1,2,3,4], multi-component superfluidity [5,6,7], topological defects [8,9,10], magnetism [11,12,13], ultracold chemistry [14] and impurity and polaron physics [15,16,17].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
