Quantum-enhanced phased array scheme based on NOON states

The key advantage of phased array technology lies in its ability to achieve beam steering via beamforming and significantly improve the signal-to-noise ratio (SNR). However, classical phased array, based on the coherent superposition of electromagnetic waves, is constrained by classical physics in both capabilities. In this work, we propose a quantum-enhanced phased array architecture exploiting the quantum coherence of N-photon entangled states. The coherent-state-based phased array (CPA) follows the conventional phased-array beamforming principle, and its beam pattern represents the angular distribution of the average light intensity. In contrast to the CPA, the beam pattern of the NOON-state-based phased array (NPA) represents the angular distribution of the intensity correlation of N entangled photons. Beamforming calculations for the NPA and CPA show that when the NPA forms a normalized beam pattern of the same shape as that of the CPA, the array aperture of the NPA can be reduced by a factor of N compared with that of the CPA. Furthermore, we explore the effects of different parameters on the SNR gains of the NPA and CPA systems, revealing the fundamental differences in their SNR performance. The results show that NPA achieves higher SNR gain than CPA under certain parameter conditions. Finally, calculations based on detection parameters demonstrate that the NPA enables a longer detection range under identical transmit power levels.