"Quantum Repeaters: How to be certain with an uncertainty?"

Abstract:
Quantum repeaters is an essential tool for a long-distance quantum  communication. Designing quantum repeaters requires a handle on the  quality of entanglement generation. We discuss how to construct a  method for truly N-partitte entanglement detection. In contrast to  conventional objects of research, mainly systems of few qubits or few  gaussian modes, we rather concentrate on the mode entanglement for  non-gaussian states. We adopt and modify conventional entanglement  measures, such as entanglement witnesses and uncertainty-based  entanglement criteria, to the case of non-gaussian N-mode states. We  show how to verify genuine N-mode entanglement with just a few  measurements.