In one minute

Becker, Guzzinati, Béché, Verbeeck and Batelaan study the Aharonov-Bohm effect, in which electromagnetic potentials affect electrons even where no field force acts. Zeilinger's theorem describes the missing classical force as the effect being dispersionless, while Shelankov predicted a quantum force in the same system. In the experiment, free electrons pass a magnetised nanorod and their far-field diffraction pattern is recorded. The pattern is asymmetric, confirming one of Shelankov's predictions and giving indirect experimental evidence of a quantum force. Their analysis shows Zeilinger's theorem and Shelankov's result are special cases of a single theorem.

Asymmetry and non-dispersivity in the Aharonov-Bohm effect