  Most experimental demonstrations of entanglement require nonclassical states
and correlated measurements of single-photon detection events. It is shown here
that entanglement can produce a large decrease in the rate of two-photon
absorption for a classical input state that can be observed using classical
detectors. These effects can be interpreted as being due to the creation of
entangled photon holes that are somewhat analogous to the holes of
semiconductor theory.
