  The curvature and twisting of spacetime rotate the angle of polarization and
imprint orbital angular momentum to photons emitted by the accretion disk near
rotating black holes. Considering polarization and orbital angular momentum as
two degrees of freedom of single-photons that can encode quantum information,
we emphasize that the particular shape of spacetime around rotating black holes
implements quantum gates and simple quantum circuits. Consequently, we
demonstrate the implementation of some elementary quantum gates, like Hadamard
or C-NOT, and simple quantum circuits, like Bell states, with photons in the
presence of spinning black holes. Detection and measurement of quantum
information encoded in photons emitted in the accretion disk around rotating
black holes may be performed by actual quantum information technology.
