  Entanglement of light and multiple vibrations is a key resource for
multi-channel quantum information processing and memory. However, entanglement
generation is generally suppressed, or even fully destroyed, by the dark-mode
(DM) effect induced by the coupling of multiple degenerate or near-degenerate
vibrational modes to a common optical mode. Here we propose how to generate
optomechanical entanglement via \emph{DM breaking} induced by synthetic
magnetism. We find that at nonzero temperature, light and vibrations are
\emph{separable} in the DM-unbreaking regime but \emph{entangled} in the
DM-breaking regime. Remarkably, the threshold thermal phonon number for
preserving entanglement in our simulations has been observed to be up to
\emph{three} orders of magnitude stronger than that in the DM-unbreaking
regime. The application of the DM-breaking mechanism to optomechanical networks
can make noise-tolerant entanglement networks feasible. These results are quite
general and can initiate advances in quantum resources with immunity against
both dark modes and thermal noise.
