Hetero-integration of Diamond Nanostructures on AlGaN-based Photonic Circuits

Recently, many efforts have been made in the development of large quantum networks, which rely on the generation and distribution of entanglement between their nodes. Spin-photon interfaces are crucial for these networks, as they enable the distribution and storage of quantum information [1]. Promising candidates for these interfaces are color centers in diamond since these contain individually controllable, optically active spin states with long coherence times [2], [3]. Moreover, highly efficient interfaces can be achieved when those color centers are embedded in photonic crystal cavities, which enhance the light-matter interaction and boost the emission rate of photons generated by the coherent zero-phonon-line transition [4]. While the diamond substrate allows for the nanofabrication of such devices [5], achieving a monolithic platform that will take advantage of those photonic crystal cavities on a large scale remains a challenge. Realizing such diamond monolithic platforms requires diamond thin films on a low-refractive-index material or an entire suspended configuration which represents a fabrication challenge [6]. To overcome these limitations, we propose the hetero-integration of diamond nanostructures (Fig. 1 a)) into AlGaN-based photonic circuits as schematically illustrated in Fig. 1 b,c). AlGaN/AlN platform has shown promising properties for developing integrated photonic chips [7]. By embedding diamond nanostructures within AlGaN-based circuits, we aim to create highly efficient, scalable spin-photon interfaces.