Weak Coherent and Heralded Single Photon Sources for Quantum Secured Imaging and Sensing

An ever-increasing demand for higher photon generation rates in quantum light sources often leads to the generation of multiple photon pairs, making quantum secure imaging, sensing, and communication vulnerable to photon number splitting (PNS) attacks. Here, we investigate the use of weak coherent sources (WCS) and heralded single-photon sources (HSPS) in conjunction with quantum key distribution protocols to mitigate these risks. Our initial observation shows that the BB84 protocol using heralded single-photon sources demonstrates an advantage in secured information transfer over the weak coherent sources. We then extend our comparative study between WCS and HSPS to high dimensional protocols and do a rigorous analysis to estimate a benchmark in quantum advantage in such schemes. When combined with high-dimensional states (hybrid encoding), the two-state non-orthogonal encoding protocol offers an increased resistance to PNS attacks. These findings suggest that integrating high-dimensional encoding can significantly strengthen the security and performance of quantum secure imaging, sensing, and communication systems, paving the way for more practical and resilient implementations.