01296nas a2200157 4500008004100000245005600041210005600097260001500153520081900168100001900987700002801006700002101034700002601055700002001081856003701101 2018 eng d00aBell monogamy relations in arbitrary qubit networks0 aBell monogamy relations in arbitrary qubit networks c2018/01/093 a

Characterizing trade-offs between simultaneous violations of multiple Bell inequalities in a large network of qubits is computationally demanding. We propose a graph-theoretic approach to efficiently produce Bell monogamy relations in arbitrary arrangements of qubits. All the relations obtained for bipartite Bell inequalities are tight and leverage only a single Bell monogamy relation. This feature is unique to bipartite Bell inequalities, as we show that there is no finite set of such elementary monogamy relations for multipartite inequalities. Nevertheless, many tight monogamy relations for multipartite inequalities can be obtained with our method as shown in explicit examples.

1 aTran, Minh, C.1 aRamanathan, Ravishankar1 aMcKague, Matthew1 aKaszlikowski, Dagomir1 aPaterek, Tomasz uhttps://arxiv.org/abs/1801.0307111923nas a2200205 45000080041000002450079000412100069001202600015001893000011002044900007002155201127900222100001911501700002511520700002011545700001711565700002311582700002011605700002311625856006911648 2017 eng d00aGenuine N -partite entanglement without N -partite correlation functions0 aGenuine N partite entanglement without N partite correlation fun c2017/06/26 a0623310 v953 a

A genuinely N-partite entangled state may display vanishing N-partite correlations measured for arbitrary local observables. In such states the genuine entanglement is noticeable solely in correlations between subsets of particles. A straightforward way to obtain such states for odd N is to design an “antistate” in which all correlations between an odd number of observers are exactly opposite. Evenly mixing a state with its antistate then produces a mixed state with no N-partite correlations, with many of them genuinely multiparty entangled. Intriguingly, all known examples of “entanglement without correlations” involve an odd number of particles. Here we further develop the idea of antistates, thereby shedding light on the different properties of even and odd particle systems. We conjecture that there is no antistate to any pure even-N-party entangled state making the simple construction scheme unfeasible. However, as we prove by construction, higher-rank examples of entanglement without correlations for arbitrary even N indeed exist. These classes of states exhibit genuine entanglement and even violate an N-partite Bell inequality, clearly demonstrating the nonclassical features of these states as well as showing their applicability for quantum information processing.

1 aTran, Minh, C.1 aZuppardo, Margherita1 ade Rosier, Anna1 aKnips, Lukas1 aLaskowski, Wieslaw1 aPaterek, Tomasz1 aWeinfurter, Harald uhttps://journals.aps.org/pra/abstract/10.1103/PhysRevA.95.062331