To get single photons, you just need to stack up enough stained glass infront of a light source. That's been acheivable for aeons (the photon will go through at

To get single photons, you just need to stack up enough stained glass infront of a light source. That's been acheivable for aeons (the photon will go through at random time though). The difficult part is single photon _detectors_, they're the key technology to explore the single-photon version of Young's experiment (which originally showed that light has wave-like properties).