  We demonstrate a sideband-resolved cavity electromechanical system operating
at room temperature. The mechanical resonator, a strongly pre-stressed silicon
nitride string, is dielectrically coupled to a three-dimensional microwave
cavity made of copper. The electromechanical coupling is characterized by two
measurements, the cavity-induced eigenfrequency shift of the mechanical
resonator and the optomechanically induced transparency. While the former is
dominated by dielectric effects, the latter reveals a clear signature of the
dynamical backaction of the cavity field on the resonator. This unlocks the
field of cavity electromechanics for room temperature applications.
