Quantum Illumination with Multiple Entangled Photons

In this work, a theoretical generalization of Lloyd's quantum illumination model for signal beams described by two entangled photon states is developed. It is shown that the new protocol is more sensitive than Lloyd's model with respect to signal-to-noise ratio (SNR) and reduces the required time-bandwidth product to have the same enhancement in the SNR. The protocol is resilient against noise, potentially resilient against losses, and offers a method to find the range of the target. However, the generation of the required three photon states for the protocol remains a technical problem for its practical implementation.