  The deflection of light in the gravitational field of the Sun is one of the
most fundamental consequences for general relativity as well as one of its
classical tests first performed by Eddington a century ago. However, despite
its center stage role in modern physics, no experiment has tested it in an
ostensibly quantum regime where both matter and light exhibit non-classical
features. This paper shows that the interaction which gives rise to the
light-bending also induces photon-matter entanglement as long as gravity and
matter are treated at par with quantum mechanics. The quantum light-bending
interaction within the framework of perturbative quantum gravity highlights
this point by showing that the entangled states can be generated already with
coherent states of light and matter exploiting the non-linear coupling induced
by graviton exchange. Furthermore, the quantum light-bending interaction is
capable of discerning between the spin-2 and spin-0 gravitons thus also
providing a test for alternative theories of gravity at short distances and at
the quantum level. We will conclude by estimating the order of magnitude of the
entanglement generated by employing the linear entropy. In particular, we find
that a half-ring cavity of radius $0.25$ m placed around a $10$ kg mechanical
oscillator operating at $150$ Hz, could be used to generate linear entropy of
order unity using a petawatt laser source at optical wavelengths. While the
proposed scheme is beyond the current experimental realities it nonetheless
initiates the discussion about testing the spin of the gravitational
interaction at the quantum level.
