High-Q Nanophotonic Resonators on Diamond Membranes using Atomic Layer Deposition TiO2

Nanophotonic resonators are critical elements in solid state quantum networks, as they enable individual optical photons to interact with quantum spin states. In diamond, current techniques to fabricate these devices often introduce significant surface roughness and lattice strain, which limit performance and scalability. Using atomic layer deposition of TiO2, we developed a nanophotonic fabrication platform that avoids substrate etching while retaining the potential for high-cooperativity interfacing with color centers in thin diamond membranes. The resulting devices are exceptionally smooth and can be built on arbitrary substrates. In this work, we fabricated ring resonators and 1D photonic crystal cavities with quality factors exceeding 10⁴ and demonstrated our platform’s potential for quantum networking applications on diamond.