
observe polarization-independent behavior for both the single counts and the
coincidence counts. In fact, the coincidence counts after subtraction of the dark-
count contributions in both cases are zero within their error-bar ranges. This is
expected because the FWM photons in this case are produced not by the reverse
degenerate FWM process, but by the conventional FWM process involving a
degenerate-frequency pump. As the filters in the experiment are configured
to look at coincidences between photons in a single band (i.e., without its
conjugate), the pairwise nature of the conventional FWM photon production is
not manifested. Hence all the recorded ...