  At the beginning of the previous century, Newtonian mechanics fell victim to
two new revolutionary theories, Quantum Mechanics (QM) and General Relativity
(GR). Both theories have transformed our view of physical phenomena, with QM
accurately predicting the results of experiments taking place at small length
scales, and GR correctly describing observations at larger length scales.
However, despite the impressive predictive power of each theory in their
respective regimes, their unification still remains unresolved. Theories and
proposals for their unification exist but we are lacking experimental guidance
towards the true unifying theory. Probing GR at small length scales where
quantum effects become relevant is particularly problematic but recently there
has been a growing interest in probing the opposite regime, QM at large scales
where relativistic effects are important. This is principally due to the fact
that experimental techniques in quantum physics have developed rapidly in
recent years with the promise of quantum technologies. Here we review recent
advances in experimental and theoretical work on quantum experiments that will
be able to probe relativistic effects of gravity on quantum properties, playing
particular attention to the role of Quantum Field Theory in Curved Spacetime
(QFTCS) in describing these experiments. Interestingly, theoretical work using
QFTCS has illustrated that these quantum experiments could be used to enhance
measurements of gravitational effects, such as Gravitational Waves (GWs).
Furthermore, verification of such enhancements, as well as other QFTCS
predictions in quantum experiments, would provide the first direct validation
of this limiting case of quantum gravity, several decades after it was
initially proposed.
