Departments 4.4, 5.3 and 5.5, PTB
B. Chichkov group at Leibniz Universität Hannover
W. H. Zurek at Los Alamos National Lab, USA
K. Hayasaka, National Institute of Information and Communication Technologies, Japan
B. Reznik group, Tel Aviv University, Israel
M. Plenio group, Universität Ulm, Germany
R. Nigmatullin, University of Sydney, Australia
S. Bagayev group, Institute of Laser Physics, Novosibirsk, Russia
This research is undertaken within the European Metrology Research Programme (EMRP) project SIB04 IonClock.
We acknowledge funding by DFG under grant number ME 3648/1-1, the DAAD, PTB and the cluster of excellence QUEST.