  Hybrid architectures integrating mesoscopic electronic conductors with
resonant microwave cavities have a great potential for investigating unexplored
regimes of electron-photon coupling. In this context, producing nonclassical
squeezed light is a key step towards quantum communication with scalable
solid-state devices. Here we show that parametric driving of the electronic
conductor induces a squeezed steady state in the cavity. We find that squeezing
properties of the cavity are essentially determined by the electronic noise
correlators of the quantum conductor. In the case of a tunnel junction, we
predict that squeezing is optimized by applying a time-periodic series of
quantized $\delta-$peaks in the bias voltage. For an asymmetric quantum dot, we
show that a sharp Leviton pulse is able to achieve perfect cavity squeezing.
