laboratoire pierre aigrain
électronique et photonique quantiques
laboratoire pierre aigrain

Séminaire - 11 mai 2009

Michael Moskalets -<br class='autobr' />Universite´ de Genève (Switzerland) and<br class='autobr' />Kharkiv Polytechnic Institute (Ukraine)
Dynamical mesoscopic capacitor

I outline a dynamical scattering theory for a mesoscopic capacitor driven by the large amplitude potential at finite frequency. The time-dependent current and the frequency-dependent noise generated by such a capacitor are presented. Then I discuss several types of circuits with a capacitor as a source of single electrons and holes : i) When a capacitor emits particles into an edge state coupled to another edge state at a quantum point contact (QPC), then the shot noise is quantized in the sense that it is proportional to the number of particles (both electrons and holes) emitted during a period. If two capacitors are coupled to a QPC at different sides then the shot noise is suppressed when they emit particles simultaneously. ii) Another configuration is if two capacitors are connected in series via an edge state. Depending on the phase lag between the potentials driving the capacitors, the second cavity can effectively absorb the carriers emitted by the first cavity or the setup works as a two-particle emitter. In the former case the second cavity effectively counts the particles emitted by the first one. The efficient counting results in nullifying of the total current. iii) And, finally, the third circuit considered comprises two capacitors and two distant Mach-Zehnder interferometers with magnetic fluxes. By changing the phase difference between the potentials the two-particle correlations (orbital entanglement) is switched on or off in a controlled manner. The two-particle correlations (from two sources of uncorrelated particles) appear as a consequence of erasing of which path information due to collisions taking place at distant interferometers. They manifest themselves as an Aharonov-Bohm effect in noise while the current is insensitive to magnetic fluxes.