Anti-Correlated Photons from Classical Electromagnetism

For any experiment with two entangled photons, some joint measurement outcomes can have zero probability for a precise choice of basis. These perfect anti-correlations would seem to be a purely quantum phenomenon. It is therefore surprising that these very anti-correlations are also evident when the input to the same experiment is analyzed via classical electromagnetic theory. Demonstrating this quantum-classical connection for arbitrary two-photon states (and analyzing why it is successful) motivates alternative perspectives concerning entanglement, the path integral, and other topics in quantum foundations.