Electro-optomechanical cooperative cooling of nanomechanical oscillator beyond resolved sideband regime

Abstract

We propose a ground-state cooling scheme for a nanomechanical oscillator (NMO) that interacts with an optical cavity via radiation pressure at one side and with a superconducting microwave cavity via a capacitor at the other side. By driving these two cavities on their respective red sidebands with extra laser and microwave fields, the NMOs dual cooling channel is created through electro-optomechanical cooperation. Differing from the conventional optomechanical system with a single optical cavity wherein ground-state cooling is limited in the resolved sideband, the proposed scheme allows the optical cavity to function in an unresolved sideband regime under the cooperation of a microwave cavity with a high quality factor, or vice versa. In a weak coupling regime we demonstrate that the NMO can be cooled to near its ground-state from a finite temperature with a cooling rate that is significantly faster than that of the single-cavity optomechanical system. The heating process can be completely suppressed by the cooperation of the dual cooling channel by appropriately selecting the systems parameters. With a decreasing thermal phonon number, the numerical results of final mechanical occupancy gradually approach the analytical cooling limit.