Degenerate entangled photon pairs source based on PPLN waveguide for quantum computation

Integrated photonic devices are expected to play a promising role in the field of quantum information science. In this paper we propose two schemes for generating polarization-mode entangled photon pairs based on titanium-indiffused waveguide on periodically polled lithium niobate by using simultaneous quasi-phase-matching of Type-I and higher order Type-0 spontaneous parametric down conversion processes in one of them and Type-II in another. The photon pairs are emitted at the wavelength of 812 nm suitable for quantum computation applications within a bandwidth of 14 and 0.2 nm, and the generation rate of the degenerate sources is 44,360 and 91 pairs/(s GHz mW) respectively, in a 1-cm long waveguide. These degenerate sources can provide maximally entangled photon pairs as the Tangle of the sources is as high as 0.9999 and 1, accordingly.