We theoretically propose a circuit of the four-body coupler for superconducting qubits based on Josephson parametric oscillators (JPOs). Our coupler for the four-body interaction has a superconducting loop, similar to a capacitively shunted flux qubit, where an external magnetic flux set to half a flux quantum is threaded. This coupler circuit is a specific setup of the circuit called superconducting nonlinear asymmetric inductive elements (SNAIL) and also is a generalization of the previously proposed one for the four-body interaction of JPOs. We clarify roles of circuit parameters in the four-body interaction and, in particular, show that the four-body coupling constant in our circuit can be significantly increased by tuning capacitance of the coupler or the area ratio of the Josephson junctions of the coupler.
@article{arxiv.2501.03578,
title = {Four-body coupler for superconducting qubits based on Josephson parametric oscillators},
author = {Ryoji Miyazaki and Tsuyoshi Yamamoto},
journal= {arXiv preprint arXiv:2501.03578},
year = {2025}
}