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 HSPS has an advantage in secured information transfer over the WCS. We then extend our comparative study between WCS and HSPS to high dimensional protocols and conduct a rigorous analysis to estimate a benchmark for quantum advantage in secure bit rate thresholds for secure information transfer. When combined with high-dimensional states (hybrid encoding), the two-state non-orthogonal encoding protocol offers an increased resistance to PNS and unambiguous state discrimination attacks. These findings suggest that integrating high dimensional encoding would strengthen the security and performance of quantum secure imaging, sensing, and communication systems for practical and resilient implementations at shorter distances.