Entanglement-assisted detection of fading targets via correlation-to-coherence conversion

Quantum illumination (QI) utilizes an entanglement-enhanced sensing system to outperform classical illumination (CI) in detecting a suspected target, despite the entanglement-breaking high loss and noise environment. In the ideal scenario when the target has known reflectivity and fixed return phase, the Gaussian nature of the channel allows the design of receivers and exact evaluation of their performance advantages, such as optical parametric amplifier receiver. In practical applications, however, targets have Rayleigh-distributed reflectivities and random return phases; such receivers become useless and more complex receivers preclude exact evaluation of the quantum advantages, due to the non-Gaussian nature of the channel and receiver [Phys. Rev. A 96, 020302 (2017)]. The correlation-to-coherence (‘C->D’) conversion module is a recently proposed receiver paradigm which has a wide application such as target detection, phase estimation, and classical communication. In this paper, we show the performance advantage over CI is maintained albeit

reduced by using the C->D module for Rayleigh-fading targets. In particular, the conversion module allows exact and efficient performance evaluation despite the non-Gaussian nature of the channel involved.