  Unifying quantum theory and general relativity is the holy grail of
contemporary physics. Nonetheless, the lack of experimental evidence driving
this process led to a plethora of mathematical models with a substantial
impossibility of discriminating among them or even establishing if gravity
really needs to be quantized or if, vice versa, quantum mechanics must be
"gravitized" at some scale. Recently, it has been proposed that the observation
of the generation of entanglement by gravitational interaction, could represent
a breakthrough demonstrating the quantum nature of gravity. A few experimental
proposals have been advanced in this sense, but the extreme technological
requirements (e.g., the need for free-falling gravitationally-interacting
masses in a quantum superposition state) make their implementation still far
ahead. Here we present a feasibility study for a table-top nanodiamond-based
interferometer eventually enabling easier and less resource-demanding quantum
gravity tests. With respect to the aforementioned proposals, by relying on
quantum superpositions of steady massive (mesoscopic) objects our
interferometer may allow exploiting just small-range electromagnetic fields
(much easier to implement and control) and, at the same time, the
re-utilization of the massive quantum probes exploited, inevitably lost in
free-falling interferometric schemes.
