For the realisation of a scalable quantum processor, elementary quantum network links interconnecting individual quantum systems are essential. Our goal is to establish such links between distant atoms, and to demonstrate the entanglement and teleportation of atomic states between them. In project E3, we will study correlations between the atomic spin and the polarisation of a single photon emitted from this atom into a high-finesse optical cavity. The photon and the atom are expected to show entanglement, since the two possible polarisations of the photon are connected to two different spin states of the atom. Based on this, we will entangle two distant atoms located in separate cavities, using correlation measurements on pairs of photons being emitted from the atoms. These measurements will project the atom pair into spin-entangled states. A natural extension of the entanglement is the teleportation of a quantum state from one atom to another. This can be done using a Bell-state measurement on the photons combined with a conditional spin-flip acting on the target atom.

In parallel, we are aiming at an extension of the atom-cavity arrangements used in project E3 to a scalable many-atom many-cavity network. To that purpose, we will use of a planar matrix of tiny optical dipole-force traps, formed by the image of a large array of digitally controlled micro mirrors (DMD's). This arrangement represents a freely configurable array of optical tweezers. It will allow one to move atoms around independently from one another, so that selected pairs of atoms can be brought to interact, e.g. in a surrounding high-finesse cavity.