Towards a 4-local coupler for superconducting flux qubits - part 2: distinguishing multi-spin interactions from lower-order effects*

Many-local coupling can be effectively achieved with artificial quantum spins but is challenging to verify experimentally. Here we present a method to characterize many-local interactions by analyzing the variation of the system’s spectral gap with the local spin fields. By using generally accessible measurement techniques, we numerically simulate experimental quantification of many-local interactions. These interactions are shown to be distinguishable from lower-order contributions, which demonstrates that the method enables robust exploration of many-local interactions across a broad range of coupling strengths and can be implemented for a variety of qubit modalities.