  Evidencing the quantum nature of gravity through the entanglement of two
masses has recently been proposed. Proposals using qubits to witness this
entanglement can afford to bring two masses close enough so that the complete
1/r interaction is at play (as opposed to its second-order Taylor expansion),
and micron-sized masses separated by 10-100 microns (with or without
electromagnetic screening) suffice to provide a 0.01-1 Hz rate of growth of
entanglement. Yet the only viable method proposed for obtaining qubit witnesses
so far has been to employ spins embedded in the masses, whose correlations are
used to witness the entanglement developed between masses during
interferometry. This comes with the dual challenge of incorporating spin
coherence-preserving methodologies into the protocol, as well as a demanding
precision of control fields for the accurate completion of spin-aided
(Stern-Gerlach) interferometry. Here we show that if superpositions of distinct
spatially localized states of each mass can be created, whatever the means,
simple position correlation measurements alone can yield a spatial qubit
witness of entanglement between the masses. We find that a significant
squeezing at a specific stage of the protocol is the principal new requirement
(in addition to the need to maintain spatial quantum coherence) for its
viability
