Benchmarking Multipartite Entanglement Generation with Graph States
As quantum computing technology slowly matures and the number of available
qubits on a QPU gradually increases, interest in assessing the capabilities of
quantum computing hardware in a scalable manner is growing. One of the key
properties for quantum computing is the ability to generate multipartite
entangled states. In this paper, aspects of benchmarking entanglement
generation capabilities of noisy intermediate-scale quantum (NISQ) devices are
discussed based on the preparation of graph states and the verification of
entanglement in the prepared states. Thereby, we use entanglement witnesses
that are specifically suited for a scalable experiment design. This choice of
entanglement witnesses can detect A) bipartite entanglement and B) genuine
multipartite entanglement for graph states with constant two measurement
settings if the prepared graph state is based on a 2-colorable graph, e.g., a
square grid graph or one of its subgraphs. With this, we experimentally verify
that a fully bipartite entangled state can be prepared on a 127-qubit IBM
Quantum superconducting QPU, and genuine multipartite entanglement can be
detected for states of up to 23 qubits with quantum readout error mitigation.
René Zander Colin Kai-Uwe Becker