Whole-device entanglement in a 65-qubit superconducting quantum computer

TL;DR

This paper demonstrates large-scale bipartite entanglement across entire 65- and 53-qubit superconducting quantum devices, showing the potential for complex quantum states in noisy intermediate-scale quantum systems.

Contribution

It is the first to show full bipartite entanglement spanning entire large superconducting quantum devices using native-graph states and error mitigation techniques.

Findings

Detected connected entanglement graphs across full devices

QREM increased observed entanglement and detected entangled pairs

Achieved full bipartite entanglement in the largest superconducting devices to date

Abstract

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.