  Although quantum physics is well understood in inertial reference frames
(flat spacetime), a current challenge is the search for experimental evidence
of non-trivial or unexpected behaviour of quantum systems in non-inertial
frames. Here, we present a novel test of quantum mechanics in a non-inertial
reference frame: we consider Hong-Ou-Mandel (HOM) interference on a rotating
platform and study the effect of uniform rotation on the distinguishability of
the photons. Both theory and experiments show that the rotational motion
induces a relative delay in the photon arrival times at the exit beamsplitter
and that this delay is observed as a shift in the position of the HOM dip. This
experiment can be extended to a full general relativistic test of quantum
physics using satellites in Earth orbit and indicates a new route towards the
use of photonic technologies for investigating quantum mechanics at the
interface with relativity.
