Quantum enhancement factor in a noisy environment and the role of transmissivity in the quantum illumination

In this paper, we use a direct detection in an optical parametric amplifier (OPA) receiver in a lossy and noisy environment and obtain the quantum enhancement factor (QEF) and error probability, which improve the quantum illumination (QI) performance. QI uses the entanglement between the signal and the idler to detect the target. Different parameters of the assumed scheme help us to improve the target detection in the current configuration. Thus, we show that the channel transmissivity function from the transmitter output to the receiver input plays an significant role in improving the QI performance. In addition, we state that the QEF increases with the increase of detector quantum efficiency and transmissivity. One of the most important applications of this work is the manufacturing of QI with optimal performance, which is very beneficial in the country's defense and research industries.