The analysis of convergence of the bistatic multiphoton quantum radar cross section

The quantum radar cross section (QRCS) is a vital basis for the design of quantum detection strategies and stealth structure optimization. To obtain an accurate multiphoton QRCS response, the target must have an adequate number of scatterers; otherwise, the response will be incorrect and highly distorted. However, the convergence of the QRCS under multiphoton detection is not yet clear. In this paper, we establish a change factor equation for multiphoton QRCS, which is verified by the typical warhead structure, a triangular plate of the bistatic quantum radar. Simulation results show that we can determine the asymptotic state of the response by establishing a change factor threshold. When the triangular plate is illuminated by six photons, a more appropriate threshold of change factor to obtain the most accurate bistatic multiphoton quantum radar cross section (BM-QRCS) response for all scattering angles would be \(-\,79\) dB. On this basis, we investigate the differences and connections between classical radar cross section (CRCS), monostatic multiphoton QRCS (MO-QRCS), and BM-QRCS. Furthermore, we reveal the effects of elevation and azimuthal incidence angles on the BM-QRCS. When selecting the appropriate elevation incidence angle and azimuthal incidence angle in the small photon number range, BM-QRCS exhibits the quantum advantage of mainlobe enhancement.