“…Entanglement distribution and QKD -high rate Compact, robust and movable, high count rate sources Single-crystal sources BBO [263,284,360], Sagnac sources [108,115,303,305], Crossedcrystal sources [62,97], Beam displacer sources [361] Satellite entanglement distribution and QKD Compact, very high count rate and mechanically stable sources Parallel-crystal sources [302], Sagnac sources [108,109,290] Teleportation/Swapping Spectrally separable biphoton states, group-velocity matching Review article [362], BBO (or BiBO) sources [363], BBO (BiBO) source with PBS [283,285,364] which also works well at telecom [255], QPM crystal source at telecom wavelengths [365], Sagnac source with group velocity match at telecom [366], Sagnac sources [291] Multi-photon entanglement Generate multiple photon-pairs with high count rates, heralded photons for multi-photon interference Crossed-crystal sources [367], Cascaded SPDC sources of triplets [3,368], multi-SPDC interference [367,369] based on BBO with PBS [364] HOM interference, Optical coherence tomography, Quantum sensing, metrology and imaging High count rate sources, spectrally factorizable Review articles [237][238][239][240]309], Single-crystal sources [351,370], Group velocity matched crystals [254,…”