Magnetic Control of the Interaction in Ultracold K-Rb Mixtures

We predict the presence of several magnetic Feshbach resonances in selected Zeeman sublevels of the isotopic pairs ${}^{40}\mathrm{K}\mathrm{\text{−}}{}^{87}\mathrm{R}\mathrm{b}$ and ${}^{41}\mathrm{K}\mathrm{\text{−}}{}^{87}\mathrm{R}\mathrm{b}$ at magnetic fields up to ${10}^3\mathrm{G}$. Positions and widths are determined combining a new measurement of the ${}^{40}\mathrm{K}\mathrm{\text{−}}{}^{87}\mathrm{R}\mathrm{b}$ inelastic cross section with recent experimental results on both isotopes. The possibility of driving a K-Rb mixture from the weak to the strong interacting regime tuning the applied field should allow one to achieve the optimal conditions for boson-induced Cooper pairing in a multicomponent ${}^{40}\mathrm{K}\mathrm{\text{−}}{}^{87}\mathrm{R}\mathrm{b}$ atomic gas and for the production of ultracold polar molecules.