For more than a century, Thomas Young’s seminal double-slit experiment was seen as a convincing demonstration that light is a wave phenomenon. The modern interpretation provided by quantum mechanics is radically different: Light comprises discrete entities called photons, and the photon wavefunction at a given location on a detector screen receives contributions from all paths that pass from the photon source through the slits (call them A and B) and on to the screen. The intensity at any location on the screen is proportional to the probability that the photon arrives at that location. According to the Born rule, that probability is given by the absolute square of the wavefunction. Interference was famously observed with light, but it is not a phenomenon limited to light. Any particle can, in theory, exhibit an interference pattern determined by the absolute square of its wavefunction.
You can destroy the characteristic double-slit interference by...
