Bounding the entanglement of N qubits with only four measurements

S. M. Hashemi Rafsanjani, C. J. Broadbent, J. H. Eberly

Published 2013-09-04, updated 2014-01-02Version 2

We introduce a new measure for the genuinely N-partite (all-party) entanglement of N-qubit states using the trace distance metric, and find an algebraic formula for the GHZ-diagonal states. We then use this formula to show how the all-party entanglement of experimentally produced GHZ states of an arbitrary number of qubits may be bounded with only four measurements.