  The generation of high-fidelity polarization-entangled photon pairs, to date,
has been demonstrated on specific spatial modes or over relatively narrow
apertures. We put forward and demonstrate an experimental scheme to extend the
temporal and spatial indistinguishability of polarization-entangled photons
over wide emission angles, which can be applied to cover the whole SPDC cone.
Over such wide angular extent, while the time-delay map is almost flat which
renders the conventional compensation via a birefringent element an appropriate
approach, the relative-phase map -- verified as a quadratic function --
necessitates a tunable compensation paradigm. Here, to do so, we employ a
phase-only two-dimensional spatial light modulator (2D SLM) loaded by the
complementary of the relative phase map to equalize the phase variations for
one third of the noncollinear spontaneous parametric down conversion (SPDC)
emission. After eliminating the temporal and spatial distinguishability over
the 2D SLM area, a 97% polarization visibility is verified for the entangled
photon pairs scattered widely across the SPDC cone.

Quantum Physics