The general perception is that the electron double-slit experiment has already been
performed. This is true in the sense that J¨onsson demonstrated diffraction from single, double,
and multiple (up to five) micro-slits [2], but he could not observe single particle diffraction,
nor close individual slits. In two separate landmark experiments, individual electron detection
was used to produce interference patterns; however, biprisms were used instead of doubleslits
[3, 4]. First, Pozzi recorded the interference patterns at varying electron beam densities.
Then, Tonomura recorded the positions of individual electron detection events and used them
to produce the well known build-up of an interference pattern. It is interesting to point out that
the build up of a double-slit diffraction pattern has been called ‘The most beautiful experiment
in physics’ [5, 6], while the build-up for a true double-slit has, up to now, never been reported.