Mechanical Entanglement via Detuned Parametric Amplification
  We propose two schemes to generate entanglement between a pair of mechanical oscillators using parametric amplification. In contrast to existing parametric drive-based protocols, both schemes operate in the steady-state. Using a detuned parametric drive to maintain equilibrium and to couple orthogonal quadratures, our approach can be viewed as a two-mode extension of previous proposals for parametric squeezing. We find that robust steady-state entanglement is possible for matched oscillators with well-controlled coupling. In addition, one of the proposed schemes is robust to differences in the damping rates of the two oscillators. 
Alex Szorkovszky, Aashish A. Clerk, Andrew C. Doherty, Warwick P.   Bowen
quant-ph cond-mat.mes-hall