## "Charge transport: from Faraday to Thouless"
The Faraday laws of electrolysis state (in modern terms) that the charge transported by a solvated ion between two electrodes is an integer multiple of the elementary charge e. But a liquid is an assembly of nuclei and electrons: while the nuclear is charges can be considered as point-like, the electronic charge is delocalized all over the cell. The moving ions drag "some" charge, whose integrated value is nonetheless ill defined. Ionic charges in solution can only be computed via some approximate formula, and are /noninteger/. So why is the electrode-to-electrode transported charge quantized? The answer (given by D. Thouless 1983) is in topology: I will give a pedagogical (and personal) presentation of this outstanding finding. |