Moebius, MichaelHerrera, FelipeGriesse-Nascimento, SarahReshef, OradEvans, ChristopherGuerreschi, Gian GiacomoAspuru-Guzik, AlanMazur, Eric2017-07-132016Moebius, Michael G., Felipe Herrera, Sarah Griesse-Nascimento, Orad Reshef, Christopher C. Evans, Gian Giacomo Guerreschi, Alán Aspuru-Guzik, and Eric Mazur. 2016. “Efficient Photon Triplet Generation in Integrated Nanophotonic Waveguides.” Optics Express 24 (9) (April 27): 9932. doi:10.1364/oe.24.009932.1094-4087http://nrs.harvard.edu/urn-3:HUL.InstRepos:33439111Generation of entangled photons in nonlinear media constitutes a basic building block of modern photonic quantum technology. Current optical materials are severely limited in their ability to produce three or more entangled photons in a single event due to weak nonlinearities and challenges achieving phase-matching. We use integrated nanophotonics to enhance nonlinear interactions and develop protocols to design multimode waveguides that enable sustained phase-matching for third order spontaneous parametric down-conversion (TOSPDC). We predict a generation efficiency of 0.13 triplets/s/mW of pump power in TiO2- based integrated waveguides, an order of magnitude higher than previous theoretical and experimental demonstrations. We experimentally verify our device design methods in TiO2 waveguides using third-harmonic generation (THG), the reverse process of TOSPDC that is subject to the same phase-matching constraints. We finally discuss the effect of finite detector bandwidth and photon losses on the energy-time coherence properties of the expected TOSPDC source.en-USnonlinear opticsintegrated opticsnonlinear optics, parametric processesquantum optics, multiphoton processesJournal Article2016-07-08201610.1364/OE.24.009932