Quantum illumination network for multi-parameter estimation

Quantum illumination is an entanglement-based target detection protocol that provides quantum advantages despite the presence of entanglement-breaking noise. However, the advantage of traditional quantum illumination protocols relies on an extremely low total transmitted power and a single spatiotemporal bin of probing, substantially limiting its practical relevance. In this work, we propose a quantum illumination network with a transmitter array and a single receiver antenna that offers a huge scaling advantage in multi-parameter estimation. At the same time, the total power to the target region (with potentially multiple targets) can be high due to the transmitter array. With this setting, we model the whole process as a multiple-access channel and design the measurement by the correlation-to-displacement conversion (CtoD) based on the use of entangled probe states. We prove that, despite the inevitable interference of different returning signals, the CtoD measurement strategy can achieve scaling advantages over arbitrary classical strategies, in the multiple-phase estimation task. The advantage also generalizes to hypothesis testing. Our work resolves the power and target bin constraint of quantum illumination and paves the way toward practical relevance.