Exploring novel photonic platforms for quantum computing through Si ion implantation

Quantum technologies hold the promise of revolutionizing computing, communication, and sensing, and integrated photonics stands as a key enabler in this realm. Silicon nitride, with its unique combination of low loss, remarkable non-linear performance, and compatibility with existing semiconductor technologies, has emerged as a promising candidate for the implementation of quantum photonic circuits. Alternately, Lithium-Niobate-OnInsulator (LNOI), a material platform well known for its high electro-optic coefficient, has also turned out to be an attractive choice for quantum integrated circuits with the development of low-loss fabrication processes. Moreover, the integration of on-chip photon sources and superconducting nanowire single-photon detectors (SNSPDs) on these platforms has paved the for scalable quantum circuits minimizing the footprint and eliminating the need for lossy interconnects. However, the integration of these components on a single material platform is often hindered by background photons from the strong classical pump light used for processes such as spontaneous parametric down-conversion (SPDC). Here, we propose silicon-implanted SiN and LNOI waveguides as a novel material platform that acts as a passive filter at visible wavelengths while imparting negligible losses in the telecom band. The implantation process can be selectively patterned with manometer precision enabling enhanced tunability of the process. Furthermore, transmission electron microscopy (TEM) results provide a thorough understanding of the material dynamics at the atomic scale allowing accurate modelling of the mode profiles. This breakthrough advances the scalability of quantum photonic technologies where the source, filters, circuits, and detectors can be integrated on a single platform.