Inseparability criteria based on bipartitions of \(N\)-qubit systems
We present a new set of inequalities to detect inseparability in \(N\)-qubit states. These are based on negative partial transposition and involve collective qubitqubit correlations of any two partitions of the entire system. They reveal the rich texture of partial separability for different partitions and can discriminate between GHZ-type and W-type entanglement, as well. We introduce a new concept of relative entanglement of two different systems and two different partitions in a qubit-ensemble. The criteria in its generic form are also applicable to non-symmetric states and states with odd or even \(N\).
inseparability criteria partial transposition partial separability many-qubit systems