  Quantum illumination is a quantum-optical sensing technique in which an
entangled source is exploited to improve the detection of a low-reflectivity
object that is immersed in a bright thermal background. Entangled sources
between microwave and optical fields can be exploited to improve detection in
microwave quantum illumination technique. We proposed a scheme to enhance the
entanglement between the output fields of microwave and optical cavity by
introducing optical parametric amplifier medium in cavity optomechanical
system. We show that improving signal-to-noise ratio and decreasing error
probability of detection can be obtained consequently even for objects with low
reflectivity in the presence of optical parametric amplifier.
