Single-photon space-like antibunching

We use heralded single photons to perform an antibunching experiment in which the clicks at the detectors are space-like separated events. The idea of such experiment dates back to the 5th Solvay conference, when it was proposed by Einstein as an expression of his concerns about quantum theory.

► The question of nonlocality of a single particle is addressed in a way first raised by Einstein.
► Heralded single photons are used to demonstrate nonlocality of single particles.
► Photon antibunching, with clicks of the detectors being space-like separated events is experimentally verified.