  Controllable multipartite entanglement is a crucial element in quantum
information processing. Here we present a scheme that generates switchable
bipartite and genuine tripartite entanglement between microwave and optical
photons via an optoelectromechanical interface, where microwave and optical
cavities are coupled to a mechanical mode with controllable coupling constants.
We show that by tuning an effective gauge phase between the coupling constants
to the "sweet spots", bipartite entanglement can be generated and switched
between designated output photons. The bipartite entanglement is robust against
the mechanical noise and the signal loss to the mechanical mode when the
couplings are chosen to satisfy the impedance matching condition. When the
gauge phase is tuned away from the "sweet spots", genuine tripartite
entanglement can be generated and verified with homodyne measurement on the
quadratures of the output fields. Our result can lead to the implementation of
controllable and robust multipartite entanglement in hybrid quantum systems
operated in distinctively different frequencies.
