Mechanical squeezing in a dissipative optomechanical system with an optical parametric amplifier

We theoretically demonstrate that an especially tuned degenerate optical parametric amplifier (OPA) inside a cavity can lead to the momentum squeezing of a moving membrane in a dissipative optomechanical system. The momentum squeezing of the membrane depends on the parametric gain and the parametric phase of the OPA, the power of the external laser driving the cavity, and the temperature of the environment. The best achievable momentum squeezing is about 2.53 dB, which is limited by the OPA. Moreover, we show that the momentum squeezing of the membrane can be detected by directly measuring the cavity output field. In addition, we find that the mechanical squeezing can be enhanced to about 10.36 dB under the joint effect of the OPA and an input broadband squeezed vacuum field.