Supplemental Material: “Observation of a Strong Atom-Dimer Attraction in a Mass-Imbalanced Fermi-Fermi Mixture”

where abg = 63.0 a0 is the background scattering length, ∆ = 0.88 G is the width, and B0 is the center of the resonance near 154.7 G. As we already pointed out in Ref. [2], the optical trap induces a differential light shift between the atom pair state and the molecular state. This leads to a lightinduced shift of the FR center. For the experiments presented in the main text, we use a near-infrared laser with a wavelength of 1064 nm (single-mode operation) in three different trap settings. Therefore, the center of the FR needs to be determined for each trap setting. To determine B0 we perform radio-frequency (rf) spectroscopy of the Feshbach molecules. For each trap setting, this is done in the following way: We prepare a nonresonant mixture of Li atoms in state Li|1〉 and K atoms in their second-to-lowest state K|2〉 several tens of mG below the approximate position of the resonance center. Here, we apply a strong 500-μs rf pulse at a variable frequency ν, several kHz below the unperturbed K|2〉→K|3〉 transition frequency ν0. This pulse drives Li|1〉-K|2〉 atom pairs into the Li|1〉K|3〉 dimer state. To determine the number of dimers associated, we subsequently dissociate the dimers into a Li|1〉 and a K|3〉 atom by a 300-μs magnetic field ramp to 154.8 G. By recording absorption images we then determine the populations N2 and N3 of the K spin states K|2〉 and K|3〉, respectively. 0 0.2 0.4