Whole-device entanglement in a 65-qubit superconducting quantum computer
The ability to generate large-scale entanglement is an important progenitor
of quantum information processing capability in noisy intermediate-scale
quantum (NISQ) devices. In this paper, we investigate the extent to which
entangled quantum states over large numbers of qubits can be prepared on
current superconducting quantum devices. We prepared native-graph states on the
IBM Quantum 65-qubit $\textit{ibmq_manhattan}$ device and the 53-qubit
$\textit{ibmq_rochester}$ device and applied quantum readout-error mitigation
(QREM). Connected entanglement graphs spanning each of the full devices were
detected, indicating bipartite entanglement over the whole of each device. The
application of QREM was shown to increase the observed entanglement within all
measurements, in particular, the detected number of entangled pairs of qubits
found within $\textit{ibmq_rochester}$ increased from 31 to 56 of the total 58
connected pairs. The results of this work indicate full bipartite entanglement
in two of the largest superconducting devices to date.
Gary J. Mooney Gregory A. L. White Charles D. Hill Lloyd C. L. Hollenberg