Quantum illumination(QI) can benefit from entanglement in target detection even it is under these entanglement destroying noise.

The aim of quantum illumination is to detect low reflective target which is embedded in a bright background thermal bath. Half of a pair of entangled optical beams is sent out to interrogate the target region. Then the returned and the retained signal beam are used to decide the presence or absence of the object. Even though the fragile entanglement is easily destroyed by the bright thermal noise, quantum-illumination protocol still has remarkable advantage over classical probe protocol. Several experiments have realized the practical protocol in quantum sensing. Recently, Weedbrook et al. show that quantum discord exhibits the role of preserving the benefits of quantum illumination while entanglement is broken.

It is advantageous to operate the frequency of the signal which interrogates the object in microwave region. But so far there is no efficient way to detect single photon in microwave region while in the visible light frequency region, ultrasensitive detection of single photon have been achieved. Such that the detection of microwave signals via the detection of their entangled optical signals is a more efficient way.