This is important – the quantum world is slowly becoming visible…

Physicists in Sweden have counted individual electrons in an electrical current for the first time. Jonas Bylander, Tim Duty and Per Delsing at Chalmers University of Technology in Goteborg directly measured the oscillations associated with single electrons in a one-dimensional chain of superconducting “islands” connected by tunnel junctions. The technique could lead to the development of a new standard for electric current (J Bylander et al. 2005 Nature 434 361).

Single-electron tunnelling events have been observed in experiments with tunnel junctions before now, but the electrons making up the current have never been directly counted one by one. In a tunnel junction two conducting islands of material are separated by thin insulating layers, through which the electrons can quantum mechanically tunnel. Since like charges repel, the electrons are forced to tunnel one by one through the junction.

Link: Counting electrons one by one (March 2005) – News – PhysicsWeb.