  What gravitational field is generated by a massive quantum system in a
spatial superposition? Despite decades of intensive theoretical and
experimental research, we still do not know the answer. On the experimental
side, the difficulty lies in the fact that gravity is weak and requires large
masses to be detectable. However, it becomes increasingly difficult to generate
spatial quantum superpositions for increasingly large masses, in light of the
stronger environmental effects on such systems. Clearly, a delicate balance
between the need for strong gravitational effects and weak decoherence should
be found. We show that such a trade off could be achieved in an optomechanics
scenario that allows to determine whether the gravitational field generated by
a quantum system in a spatial superposition is in a coherent superposition or
not. We estimate the magnitude of the effect and show that it offers
perspectives for observability.
