Towards a heralded single-photon source from nitrogen molecule defects in silicon nitride waveguides

Crucial to quantum technology is the ability to deterministically generate pure single photons. One approach uses a modified Duan, Lukin, Cirac, and Zoller (DLCZ) protocol on Raman-active ensembles. Using the spontaneous Stokes Raman interaction, a pump laser pulse photon annihilates, creating a Stokes photon and collective excitation in a Raman-active medium. The detection of the Stokes photon heralds the existence of an excitation in the medium, which can be read out deterministically as an anti-Stokes photon with the application of a second laser pulse.

In this work, we investigate an integrated DLCZ single-photon source using interstitial nitrogen molecules trapped in as-grown amorphous silicon nitride waveguides. We show experimental progress demonstrating photon-pair generation in a phase-mismatched waveguide. Using mode propagation simulations in a waveguide, we develop a dual-wavelength experimental scheme. This scheme improves the photon-pair generation rate through satisfying phase matching and reduces sources of error from spontaneous four-wave mixing, supercontinuum generation, and photoluminescence. Finally, we discuss progress characterizing the photon purity from nitrogen defect emission with second-order coherence function autocorrelation and cross-correlations with quantum applications in mind.