We report on the coherence of Greenberger-Horne-Zeilinger (GHZ) states comprised of up to 8 qubits in the IBM ibmqx5 16-qubit quantum processor. In particular, we evaluate the coherence of GHZ states with N=1,…,8 qubits, as a function of a delay time between state creation and measurement. We find that the decay in coherence occurs at a rate that is linear in the number of qubits. This is consistent with a model in which the dominant noise affecting the system is uncorrelated across qubits.
@article{arxiv.1712.07080,
title = {Decoherence of up to 8-qubit entangled states in a 16-qubit superconducting quantum processor},
author = {Asier Ozaeta and Peter L. McMahon},
journal= {arXiv preprint arXiv:1712.07080},
year = {2019}
}