Dissipation-driven squeezed and sub-Poissonian mechanical states in   quadratic optomechanical systems
  In this work we study an optomechanical system in which there is a purely quadratic optomechanical coupling between the optical and mechanical modes. The optical mode is pumped by three coherent fields and the mechanical mode is parametrically driven. We show that if the frequencies and amplitudes of both optical and mechanical drivings are properly chosen, the optomechanical interaction gives rise to an effective interaction, which, in the presence of optical damping and in the absence of mechanical damping, has the squeezed vacuum state and the squeezed one phonon state as dark states of the dynamics. These states are well known for presenting quadrature squeezing and sub-Poissonian statistics. However, even in the presence of mechanical damping it is possible to find steady states with large degrees of quadrature squeezing or strong sub-Poissonian statistics. Furthermore, we find a counter-intuitive behavior in which a nonzero temperature of the mechanical environment allows the observation of mechanical states with more pronounced sub-Poissonian statistics. 
T. Figueiredo Roque and A. Vidiella-Barranco
quant-ph