Two-Source Particle Interference

In 1961, Claus Jönsson performed a double-slit experiment with electrons and obtained the expected interference pattern. In 1974, Pier G. Merli, Gian F. Missiroli, and Giulio Pozzi performed a more advanced double-slit experiment with electrons, in which only one electron was in the apparatus at a given time, and also obtained the expected interference pattern. These experiments demonstrate that the behavior of electrons in double-slit experiments is analogous to those of photons described in Section 4.1.5. The only way in which to account for the results of the Merli-Missiroli-Pozzi experiment is to assume that an individual electron incident on a double-slit apparatus passes though both slits, and then interferes with itself when it reaches the detection screen. In other words, an electron in the apparatus is partly in a state in which it passed through one slit, and partly in a state in which it passed through the other. Moreover, the interference between these two states at the screen can only determine the probability of the electron being observed at a given point on the screen.