Markus Buttiker

University of Geneva

Viernes 5/9/2008, 14 hs
Aula Federman, 1er piso, Pabellón I 

In small conductors at low temperatures, the wave nature of electrons becomes important. I briefly review the development of the  Aharonov-Bohm  (AB) effect as a tool to demonstrate quantum interference and discuss a novel AB effect in which two particles are necessary to enclose a flux, which can be tested by current fluctuations known as shot noise. Of interest are geometries  where the two-particle AB effect even when there exists no single-particle AB effect. At zero-temperature the novel AB effect is a witness of orbital entanglement: its amplitude directly determines the degree of violation of a Bell inequality. At finite temperatures the entanglement detectable by currents and current correlations is quantified by the reduced density matrix. In contrast to optical detectors, electrical conductors can  exchange particles with the sample, necessitating a completely novel discussion of entanglement detection .