Controllable optomechanically induced transparency and ponderomotive squeezing in an optomechanical system assisted by an atomic ensemble

We propose a system for realizing controllable optomechanically induced transparency (OMIT) and ponderomotive squeezing. In this system, an atomic ensemble driven by an external optical field couples with the cavity field in a typical optomechanical cavity. When the cavity is driven by a coupling laser and a probe laser, we can produce a switch for the probe field and adjust the width of the transparency window flexibly by manipulating the coupling strength between the atomic ensemble and the external optical field. We also investigate the ponderomotive squeezing properties of the transmitted field by analyzing its spectrum. Interestingly, the coupling strength between the atomic ensemble and the cavity field plays an important role in controlling the squeezing properties and the squeezing spectrum presents distinct features at red-detuned and bluedetuned frequencies by adjusting the coupling strength.