Hybrid Quantum Photonics Based on Artificial Atoms Placed Inside One Hole of a Photonic Crystal Cavity

Spin-based, quantum-photonics promise to realize distributed quantum computing and quantum networks. The performance depends on an efficient entanglement distribution where cavity quantum electrodynamics could boost the efficiency. The central challenge is the development of compact devices with large spin-photon coupling rates and a high operation bandwidth. Photonic crystal cavities comprise strong field confinement but require highly accurate positioning of atomic systems in mode field maxima. Negatively charged silicon-vacancy centers in diamond emerged as promising atom-like systems. Spectral stability and access to long-lived, nuclear-spin memories enabled elementary demonstrations of quantum network nodes, including memory-enhanced quantum communication. In a hybrid approach, we deterministically place SiV-containing nanodiamonds inside one hole of one-dimensional, freestanding, Si3N4-based photonic crystal cavities and coherently couple individual optical transitions to cavity modes. We optimize light–matter coupling utilizing two-mode composition, waveguiding, Purcell-enhancement, and cavity-resonance tuning. The resulting photon flux increases by 14 compared to free space. Corresponding lifetime-shortening below 460 ps puts potential operation bandwidth beyond GHz rates.