  We investigate the relation between indistinguishability and quantum
entanglement in Hong- Ou-Mandel-interference experiments theoretically and
relate these quantum mechanical principles to the theorem of entanglement
monogamy. Employing Glaubers theory of quantum coherence we compute the
detection statistics in HOM-interference of frequency entangled photons, and
find a new additional term in the coincidence detection probability, which is
related to the spectral indistinguishability of the considered photons that
arises from finite bandwidth effects, and therefore is relevant in the limit of
low frequency separations or large single-photon bandwidths. Compared to
previous work in that context we treat all photonic degrees of freedom (DOF) on
equal footing.

Quantum Physics