Who first performed the double-slit experiment with electrons?

Claus Jönsson first performed the double-slit experiment with electrons.

Jönsson carried out the work at the University of Tübingen, conducting the experiment in 1959 for his doctoral research and publishing the results in 1961. He used focused, coherent electron beams directed through extremely fine artificial slits and observed interference fringes. His apparatus demonstrated that electrons, despite being detected as individual particles, can produce a wave-like interference pattern.

The result extended Thomas Young’s earlier double-slit work with light. Young’s experiment, described around 1801, established the wave behavior of visible light; it did not involve electrons. Richard Feynman later used the single-electron version as a powerful conceptual illustration of quantum mechanics, but he was not the first person to perform it experimentally.

Jönsson’s original setup used multiple slits as well as two-slit arrangements, and he observed interference with up to five slits. Later experiments, including work by Pier Giorgio Merli, Gian Franco Missiroli, and Giulio Pozzi in 1974, showed how the pattern builds statistically when electrons are sent one at a time. The experiment is therefore a classic demonstration of wave-particle duality.