Fate of an impurity in a binary bosonic mixture

Together with Giacomo Bighin and Tommaso Macrì, we studied the problem of a mobile impurity immersed in a bosonic mixture. We focused on the experimental relevant case of a ⁴¹K−⁸⁷Rb mixture, prepared in its ground-state, with the impurity consisting of a few ⁴¹K atoms in the second-lowest hyperfine state. We provided a compressive picture of the impurity across the mixture phase diagram. In the droplet phase, under realistic experimental conditions, we found exotic bound-states where the impurity localized either at the center or at the droplet surface. Our findings provide new insights for the study and detection of Bose polarons in collisionally stable and long-lived Bose mixtures such as the ⁴¹K-⁸⁷Rb one.

G. Bighin et al.
Impurity in a heteronuclear two-component Bose mixture
Phys. Rev. A 106, 023301 (2022)