Світло: хвиля й квант

Light exhibits wave-like and particle-like properties. In a double-slit experiment, an interference pattern can build up from detections of individual photons; each detection on the screen is localized. This does not mean a photon simply switches between two familiar classical pictures: wave-like probability amplitudes and discrete measurement belong to the quantum description. When the setup makes it possible to determine which slit a photon passed through, the interference disappears in the described experiment.