Entanglement in a 20-Qubit Superconducting Quantum Computer
Towards realising larger scale quantum algorithms, the ability to prepare
sizeable multi-qubit entangled states with full qubit control is used as a
benchmark for quantum technologies. We investigate the extent to which
entanglement is found within a prepared graph state on the 20-qubit
superconducting quantum computer, IBM Q Poughkeepsie. We prepared a graph state
along a path consisting of all twenty qubits within Poughkeepsie and performed
full quantum state tomography on all groups of four connected qubits along this
path. We determined that each pair of connected qubits was inseparable and
hence the prepared state was entangled. Additionally, a genuine multipartite
entanglement witness was measured on all qubit subpaths of the graph state and
we found genuine multipartite entanglement on chains of up to three qubits.
Gary J. Mooney Charles D. Hill Lloyd C. L. Hollenberg