Towards a basic quantum repeater link over 400m with heralded entanglement of 87Rb-atoms

This paper presents progress towards creating entanglement between two single trapped ⁸⁷Rb-atoms over a distance of 400m. The scheme starts by entangling each atom with a photon. In the next step the two photons are projected onto an entangled state via interferometric Bell-state analysis. The detection of the two photons heralds entanglement of the two atoms as was recently verified at a distance of 20m. The next step is increasing the physical distance of the atom traps to 400m. Furthermore a detection scheme consisting of state dependent ionization and subsequent detection of the ionization fragments will be implemented. This fast and efficient state measurement scheme will allow the measurement of the state of an atomic qubit in less than 1μs.