Indistinguishable photon pair generation using two independent silicon wire waveguides

CMOS-compatible photonic devices for single-photon generation

“…3, when there is only one pump, the generated photons are at two different frequencies ωs and ω i , satisfying energy conversion ωs + ω i = 2ωp and phase matching ks + k i + 2 P − 2kp = 0; while when there are two pump waves at different frequencies ω p1 and ω p2 , the generated photons are frequency degenerate at ω s,i , also meeting the requirement of energy conversion 2ω s,i = ω p1 + ω p2 and phase matching 2k s,i + (P 1 + P 2 ) − k p1 − k p2 = 0 [25]. The former process can be used for heralded single-photon generation [26][27][28][29][30][31][32][33][34][35][36][37], and the latter can be used for indistinguishable photon-pair generation [38][39][40]. Phase matching is achieved by engineering the dispersion profile of the device through designing the device geometry and tailoring the waveguide core-cladding index contrast by the use of different cladding materials.…”

“…Such a small area and high index contrast result in an extremely high nonlinearity and anomalous dispersion in the telecommunication 1,550-nm band for TE poloarized pump. This enables efficient SFWM for photon generation over a broad bandwidth in only a few millimeters long nanowires [26][27][28][29]. More importantly, CMOS fabrication techniques allow the addition of inverse tapers at both input and output ends of a nanowire [ Fig.…”

“…More importantly, CMOS fabrication techniques allow the addition of inverse tapers at both input and output ends of a nanowire [ Fig. 4(b)] for fiber pigtailing, which significantly improves the photon collection efficiency and system stability [28,41].…”

“…8(a)]. This involves the measurements of four-photon coincidence events [28], which are much less likely to happen because each heralded photon source generates photons randomly. To make such a heralded single-photon source useful, we have to improve it to the nearly deterministic regime using the multiplexing schemes discussed later in Section 4.1.…”

Two-photon interferences with degenerate and nondegenerate paired photons

“…In the well-known Hong-OuMandel (HOM) interference [3,4], it was found that two identical photons coalesce in the BS and go together into the same output port. This two-photon quantum interference effect has been confirmed from paired photons in spontaneous parametric down-conversion [3], four-wave mixing [5], and single photons from independent sources [6,7]. In these experiments, the indistinguishability between the two photons is the key for observing the HOM effect where the detectors are slow as compared to the bandwidth of the photons.…”