Abstract
The article "A brief history of the double-slit experiment" (September 2002 p15; correction October p17) describes how Claus Jönsson of the University of Tübingen performed the first double-slit interference experiment with electrons in 1961. It then goes on to say: "The next milestone – an experiment in which there was just one electron in the apparatus at any one time – was reached by Akira Tonomura and co-workers at Hitachi in 1989 when they observed the build-up of the fringe pattern with a very weak electron source and an electron biprism (Am. J. Phys. 57 117–120)."