Lack of dispersion cancellation with classical phase-sensitive light

TL;DR

This paper demonstrates that classical phase-sensitive light does not exhibit nonlocal dispersion cancellation, clarifying the fundamental differences between classical and quantum optical correlations.

Contribution

It clarifies that classical phase-sensitive light cannot achieve dispersion cancellation, contrasting with quantum entangled photon pairs, and explains the different origins of correlations in classical and quantum regimes.

Findings

Classical phase-sensitive light does not cancel dispersion.

Dispersion affects both classical and quantum beams similarly.

Cross-correlations in classical light differ fundamentally from quantum entanglement.

Abstract

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.