  We show that an interlayer exciton condensate doped into a strongly
correlated Mott insulator exhibits a remarkable enhancement of the bandwidth of
the magnetic excitations (triplons). This triplon is visible in the dynamical
magnetic susceptibility and can be measured using resonant inelastic X-ray
scattering. The bandwidth of the triplon scales with the exciton superfluid
density, but only in the limit of strong correlations. As such the triplon
bandwidth acts as a probe of exciton-spin interactions in the condensate.
