  The generation of quantum entanglement of macroscopic or mesoscopic bodies in
mechanical motion is generally bounded by the thermal fluctuation exerted by
their environments. Here we propose a scheme to establish stationary
entanglement between two mechanically oscillating mirrors of a cavity. It is
revealed that, by applying a broadband squeezed laser acting as a
squeezed-vacuum reservoir to the cavity, a stable entanglement between the
mechanical mirrors can be generated. Using the adiabatic elimination and master
equation methods, we analytically find that the generated entanglement is
essentially determined by the squeezing of the relative momentum of the
mechanical mirrors, which is transferred from the squeezed reservoir through
the cavity. Numerical verification indicates that our scheme is within the
present experimental state of the art of optomechanics.
