Two-dimensional optomechanical crystals for quantum optomechanics

We present a novel two-dimensional optomechanical crystal design that integrates a photonic nanocavity within a phononic crystal shield. This architecture achieves strong optical confinement, GHz-frequency mechanical modes, and high vacuum optomechanical coupling rates, validated by both simulations and experiments. The device overcomes limitations of traditional nanobeams by offering improved thermalization, mode localization flexibility, and scalability. With measured optical quality factors around 10⁵ and Q·f products near 10¹³, this platform shows promise for quantum operation at intermediate temperatures, including potential ground-state cooling from 4 K. These results establish 2D optomechanical crystals as robust candidates for advanced quantum optomechanics and precision measurements near fundamental limits.