Rydberg atoms are neutral atoms  (e.g. rubidium, caesium)  with a highly excited outer electron  (typically n=30 to 100).  They show a state dependent pairwise interaction that can be twelve orders of magnitude higher for two excited atoms than for ground state atoms.

 

In terms of quantum control by exciting the atoms with time-dependent lasers one can turn on and off the interaction between atoms and create entanglement between atoms.

                                                                           

Experimental achievements among others have been entanglement creation, realization of a 2 qubit gate and a single photon source.  This makes  Rydberg atoms a promising global approach to quantum communication and quantum computation at room temperature.

 

A main part of our work in this context is to shape the exciting pulses by means of optimal control in a way to make best use of these effects in the framework of quantum computation and communication applications and thus shift its limits. This includes optimization of 2-qubit gates, also in the context of non-local control schemes for optically trapped rubidium atoms and the analysis and optimization of a single photon source consisting of a hot rubidium vapor via matrix product state time simulation.