  Coherent coupling between excitons is at the heart of many-body interactions
with transition metal dichalcogenide (TMD) heterostructures as an emergent
platform for the investigation of these interactions. We employ
multi-dimensional coherent spectroscopy on monolayer
MoSe\textsubscript{2}/WSe\textsubscript{2} heterostructures and observe
coherent coupling between excitons spatially localized in monolayer MoSe$_2$
and WSe$_2$. Through many-body spectroscopy, we further observe the absorption
state arising from free interlayer electron-hole pairs. This observation yields
a spectroscopic measurement of the interlayer exciton binding energy of about
250 meV.
