  We consider the hypothesis that nonlocal, omnidirectional, causally-coherent
quantum entanglement of inflationary horizons may account for some well-known
measured anomalies of Cosmic Microwave Background (CMB) anisotropy on large
angular scales. It is shown that causal coherence can lead to less cosmic
variance in the large-angle power spectrum ${C}_\ell$ of primordial curvature
perturbations on spherical horizons than predicted by the standard model of
locality in effective field theory, and to new symmetries of the angular
correlation function ${C}(\Theta)$. Causal considerations are used to construct
an approximate analytic model for ${C}(\Theta)$ on angular scales larger than a
few degrees. Allowing for uncertainties from the unmeasured intrinsic dipole
and from Galactic foreground subtraction, causally-coherent constraints are
shown to be consistent with measured CMB correlations on large angular scales.
Reduced cosmic variance will enable powerful tests of the hypothesis with
better foreground subtraction and higher fidelity measurements on large angular
scales.
