  Recently a theoretical and an experimental protocol known as quantum gravity
induced entanglement of masses (QGEM) has been proposed to test the quantum
nature of gravity using two mesoscopic masses each placed in a superposition of
two locations. If, after eliminating all non-gravitational interactions between
them, the particles become entangled, one can conclude that the gravitational
potential is induced via a quantum mediator, i.e. a virtual graviton. In this
paper, we examine a range of different experimental set-ups, considering
different geometries and the number of spatially superposed states taken, in
order to determine which would generate entanglement faster. We conclude that
without decoherence, and given a maximum distance $\Delta x$ between any two
spatial states of a superposition, a set of two qubits placed in spatial
superposition parallel to one another will outperform all other models given
realistic experimental parameters. Furthermore, when a sufficiently high
decoherence rate is introduced, multi-component superpositions can outperform
the two-qubit set-up. This is further verified with an experimental simulation,
showing that $O(10^3)$ measurements are required to reject the no entanglement
hypothesis with a parallel qubits set-up without decoherence at a 99.9$\%$
confidence level. The number of measurements increases when decoherence is
introduced. When the decoherence rate reaches $0.125$~Hz, 6-dimensional qudits
are required as the two-qubit system entanglement cannot be witnessed anymore.
However, in this case, $O(10^6)$ measurements will be required. One can group
the witness operators to measure in order to reduce the number of measurements
(up to ten-fold). However, this may be challenging to implement experimentally.
