Extended Data Fig. 4: Hyperfine transitions of NaK molecules in the modulation spectra.

a, Tetramer dissociation spectrum (blue) compared to background loss (orange). The background loss is measured under the same condition as the dissociation spectrum, except with a fast ramp over the FL resonance so that no tetramers are formed. The absence of loss in the background measurement suggests that the dissociation spectrum is not affected by either the hyperfine transitions or the association. This is ensured by using a small modulation amplitude of 1. 4° over a duration of 2 ms and by taking the measurements away from known hyperfine transitions. The error bars represent standard error of the mean of ten repetitions. b, Hyperfine spectrum measured with Landau–Zener sweeps in the modulation frequency and a modulation amplitude of 11° (purple) and 3. 6° (green). The transitions with the larger modulation amplitude is power broadened compared to the lower amplitude ones. The modulation frequency that we use for the tetramer dissociation spectrum are marked as vertical dashed lines. The error bars represent standard error of the mean of four repetitions.