Dieter Meschede

In the so called bottom-up approach to controlled atomic quantum matter small quantum systems are synthesized involving single, few or many atom systems. I will discuss two examples:

I will show that controlled interaction of atoms with a so called fast optical resonators leads not only to a strongly preferred emission of light into optical wave guides (Purcell effect) but also to speed higher than conventional atomic decay rates. This device will be useful for future interconnects in hybrid quantum networks: We have taken first steps towards coupling broad band (e.g. quantum dot) photons to narrow band fiber coupled atomic memories. Quantum networks will have to rely on so called quantum repeaters for large scale distribution of quantum states. Quantum repeaters remain an enormous challenge for experimenters.With quantum walks – i. e. driven discrete transport on a lattice conditioned on the spin state – we operate a tool realizing controlled coherent transport of atoms over tens of lattice sites – up to the so called quantum speed limit available. I will present the experimental realization of “ideal negative measurements” showing strong violation of the Leggett-Gard inequality. The experiment distinguishes quantitatively the macro realist’s world from the quantum world. A few more examples including e.g. the creation of artificial magnetic fields will be given. The ultimate aim of these experiments is the creation of quantum cellular automata.