  To generate entangled photon pairs via quantum dots (QDs), the exciton fine
structure splitting (FSS) must be comparable to the exciton homogeneous line
width. Yet in the (In,Ga)As/GaAs QD, the intrinsic FSS is about a few tens
$\mu$eV. To achieve photon entanglement, it is necessary to Cherry-pick a
sample with extremely small FSS from a large number of samples, or to apply
strong in-plane magnetic field. Using theoretical modeling of the fundamental
causes of FSS in QDs, we predict that the intrinsic FSS of InAs/InP QDs is an
order of magnitude smaller than that of InAs/GaAs dots, and better yet, their
excitonic gap matches the 1.55 $\mu$m fiber optic wavelength, therefore offer
efficient on-demand entangled photon emitters for long distance quantum
communication.
