Waveguide-Cavity Scattering in High-Frequency Dissipative Optomechanics

The coherent transduction of information between microwave and optical domains is a fundamental building block for future quantum networks. A promising way to bridge these widely different frequencies is using high-frequency nanomechanical resonators interacting with low-loss optical modes. State-of-the-art optomechanical devices require a relatively large photon population in the cavity to enhance the acousto-optic coupling, the heat arising from undesirable optical absorption, however, generates thermal phonons that ultimately hinder their operation in the quantum regime. One way to overcome this problem is by using dissipative optomechanics. In this framework, photons can be scattered directly from a waveguide into a resonator, reducing the need for a large intra-cavity photon population. Hitherto, such dissipative optomechanical interaction was only demonstrated at low mechanical frequencies, precluding the quantum state transfer between photonic and phononic domains. Here, we show the first dissipative optomechanical system operating in the sideband-resolved regime, where the mechanical frequency is larger than the optical linewidth. Exploring this unprecedented regime, we demonstrate the impact of dissipative optomechanical coupling in reshaping both mechanical and optical spectra. Our figures represent a two-order-of-magnitude leap in the mechanical frequency and a tenfold increase in the dissipative optomechanical coupling rate compared to previous works. The present demonstration opens a path to strongly dissipative optomechanical devices with nearly noiseless operation in the quantum regime.