Mermin's Inequalities of Multiple qubits with Orthogonal Measurements on IBM Q 53-qubit system

TL;DR

This paper investigates the entanglement properties of multi-qubit GHZ-like states on IBM's 53-qubit quantum computer using Mermin inequalities, revealing that entanglement quality varies with chain length and connectivity.

Contribution

It introduces a method using orthogonal measurements to assess entanglement and compares experimental violations with theoretical predictions on a large-scale quantum device.

Findings

Entanglement is strong for N ≤ 4 qubits.

Violation of Mermin inequalities decreases with more qubits.

Connectivity affects entanglement validity in longer chains.

Abstract

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.