Growing macroscopic superposition states via cavity quantum optomechanics

The investigation of macroscopic quantum phenomena is a current active area of research that offers significant promise to advance the forefronts of both fundamental and applied quantum science. Utilizing the exquisite precision and control of quantum optics provides a powerful toolset for generating such quantum states where the types and 'size' of the states that can be generated are set by the resourcefulness of the protocol applied. In this work we present a new scheme for 'growing' macroscopic superposition states of motion of a mechanical oscillator via cavity quantum optomechanics. The scheme consists of a series of optical pulses interacting with a mechanical mode via radiation-pressure followed by photon-counting measurements. The multistep nature of our protocol allows macroscopic superposition states to be prepared with a relaxed requirement for the single-photon optomechanical coupling strength. To demonstrate the feasibility of our scheme, we quantify how initial mechanical thermal occupation and decoherence affects the non-classicality and macroscopicity of the states generated. We show that under realistic experimental conditions, mechanical quantum states can exhibit significant non-classicality and can be grown to a macroscopic scale.