Cross-Molecular Coupling in Combined Photoassociation and Feshbach Resonances

Photoassociation of a Feshbach-resonant condensate has revealed a shift of the laser resonance that is blue (red) below (above) the Feshbach resonance, as well as a rate constant that vanishes at a particular below-resonance magnetic field and saturates near-resonance at unprecedented values ($\sim10^{-7}$ cm$^3$/s). Here we report that cross-molecular coupling, enabled by the shared dissociation continuum, is implicated as the culprit behind these observations.