Photon noise refers to the uncertainty in the number of photons detected by a sensor due to the random nature of photon arrivals. This noise source is inherent in many imaging and sensing applications that rely on photon detection, such as astrophotography, microscopy, and quantum imaging. Photon noise can impact the accuracy and resolution of imaging systems, and researchers often study methods to mitigate or minimize its effects for better image quality and measurement precision. Techniques to address photon noise may include increasing exposure time, using signal processing algorithms, or improving sensor technology.