Optomechanical coupling between a multilayer graphene mechanical resonator and a superconducting microwave cavity

The combination of low mass density, high frequency and high quality factor, Q, of mechanical resonators made of two-dimensional crystals. such as graphene(1-8) make them attractive for applications in force/mass sensing and exploring the quantum regime of mechanical motion. Microwave optomechanics with superconducting cavities(9-14) offers exquisite position sensitivity(10) and enables the preparation and detection of mechanical systems in the quantum ground state(15,16). Here, we demonstrate coupling between a multilayer graphene resonator with quality factors up to 220,000 and a high-Q superconducting cavity. Using thermomechanical noise as calibration, we achieve a displacement sensitivity of 17 fm Hz(-1/2). Optomechanical coupling is demonstrated by optomechanically induced reflection and absorption of microwave photons(17-19). We observe 17 dB of mechanical microwave amplification(13) and signatures of strong optomechanical back-action. We quantitatively extract the cooperativity C, a characterization of coupling strength, from the measurement with no free parameters and find C = 8, which is promising for the quantum regime of graphene motion.