"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.