Decoy-State QKD 3D — Photon-Number-Splitting Interception

This 3D scene flies real weak-coherent laser pulses down a beamline from Alice to Bob, each rendered as a cluster of glowing spheres whose count is drawn live from the genuine Poisson distribution that governs attenuated laser light — most pulses carry a single photon, but some carry two or more, and it is exactly those multi-photon pulses a photon-number-splitting eavesdropper can silently tap. Toggle the intercept station to watch it act differently depending on each pulse's true photon count: single-photon pulses vanish at the station (blocked as too risky to touch), while multi-photon pulses have one sphere peeled off toward Eve and the remainder forwarded onward. Alice mixes real signal, decoy and vacuum intensities into the stream, and the live Gain and Yield readouts show the attack's real, computed signature — matched signal-intensity statistics hiding a collapsing decoy-intensity Gain and single-photon yield, exposing exactly what plain BB84 eavesdropping detection would miss.