  Entanglement properties of IBM Q 53 qubit quantum computer are carefully
examined with the noisy intermediate-scale quantum (NISQ) technology. We study
GHZ-like states with multiple qubits (N=2 to N=7) on IBM Rochester and compare
their maximal violation values of Mermin polynomials with analytic results. A
rule of N-qubits orthogonal measurements is taken to further justify the
entanglement less than maximal values of local realism (LR). The orthogonality
of measurements is another reliable criterion for entanglement except the
maximal values of LR. Our results indicate that the entanglement of IBM
53-qubits is reasonably good when N <= 4 while for the longer entangle chains
the entanglement is only valid for some special connectivity.
