We investigate a general scheme for generating, either dynamically or in the
steady state, continuous variable entanglement between two mechanical
resonators with different frequencies. We employ an optomechanical system in
which a single optical cavity mode driven by a suitably chosen two-tone field
is coupled to the two resonators. Significantly large mechanical entanglement
can be achieved, which is extremely robust with respect to temperature.Comment: To appear in New J. Phys. Small extensions in response to the points
raised by the referee and Refs adde