Contact: Prof. Markus Büttiker

Team spring 2003

A schematic picture of the chaotic dot-supercondctor analog of the Hanbury Brown-Twiss experiment [1].

Nanoscopic Dielectrics And Mesoscopic Properties of Superconductors
The group's research focuses on electron transport in structures that are so small that electron wave interference is relevant. Of interest are processes which can destroy quantum interference effects and describe the transition from mesoscopic behavior to macroscopic behavior. The group has played a leading role in the development of a theory of shot noise of such small systems. Shot noise permits to reveal properties of a conductor which are not accessible through conductance measurements. In particular we have recently investigated shot noise of hybrid normal superconducting systems. The superconductor acts as a source of Cooper pairs.
For experimentally relevant geometries we have investigated the conditions under which Cooper pairs can change the sign of current-cross-correlations. Cooper pairs emitted by a superconductor represent pairs of entangled electrons. We presently work out predictions for an experiment which can reveal the entanglement. The realization of source of entangled electrons would open a field similar to quantum optics but now with massive particles.
An alternative way of learning more about the properties of a small system without driving the system to far out of equilibrium is two parameter pumping. Two perturbations (voltages) oscillating slowly at the same frequency but with a phase lag applied to a conductor can generate a directed current.

References:
[1] P. Samuelsson, M. Büttiker, Phys. Rev. Lett. 89, 046601(2002).
[2] P. Samuelsson, E. V. Sukhorukov and M. Büttiker, cond-mat/0303531.
[3] M. Moskalets, M. Büttiker, Phys. Rev. B 66, 205320 (2002).