project title: Cooper pair pumping
project leader: Dr. Sigmund Köhler
access given (in days): 14
access used (in days): 5
local host: Prof. Jukka Pekola
home institution: Innstitut fur Physik, Universität Augsburg
country of institution: Germany
starting date (yyyy-mm-dd): 2007-05-21
Cooper pair pumps operate normally in the adiabatic mode, i.e., at frequencies which are low enough to keep the system in its ground state. Yet it would be useful to increase the frequency further still being able to conduct a current which is accurately controlled. This can possibly be done in the non-adiabatic regime. Discussions with Dr. Köhler have been started and the purpose of his visit is to find strategies to employ Cooper pair pumps in the non-adiabatic regime.
The visit of Köhler to the ULTI site was useful in the sense that he initiated an idea of an experiment where influence of dissipation on quantum coherent Cooper pair pumping in the adiabatic regime can be investigated. This experiment, after the successful experiment at the ULTI site on Berry phase in a Cooper pair pump is already in preparation. As to the non-adiabatic pumping, the plans have not yet developed very far, although very recently the idea has been revisited in discussions between the researchers of the ULTI site and NEC (Japan). The ideas of Köhler were very useful in planning the NEC collaboration.