  J.H. Shapiro recently argued that nonlocal dispersion cancellation using
entangled pairs of photons is essentially classical in nature, based on a
comparison with a classical model in which two stationary, chaotic beams of
light have phases and frequencies that are anti-correlated, which he refers to
as "phase-sensitive" light (arXiv:0909.2514). It is shown here that there is no
physical cancellation of dispersion for classical light of that kind, and
Shapiro's results merely reflect the fact that identical dispersion occurs in
both beams. The origin of the cross-correlations between the intensities of the
two beams is shown to be completely different in the classical and
quantum-mechanical cases.
