Spectral factorable biphotons for an unfiltered heralded single photon source at telecom wavelength

Spectrally unentangled biphotons with high single-spatiotemporal-mode purity are highly desirable for many quantum information processing tasks. This talk will describe the generation of biphotons with an inferred heralded-state spectral purity of 99%, the highest to date without any spectral filtering, by pulsed spontaneous parametric downconversion in a custom-fabricated periodically-poled KTiOPO4 crystal under extended phase-matching conditions. Two methods of characterizing the joint spectral intensity of the biphotons will be considered. Recent progress on interference visibility between independent photons generated from this heralded photon source with two subsequent laser pulses will also be discussed.