Superconducting (or Andreev) spin qubits have recently emerged as an alternative qubit platform with realizations in semiconductor-superconductor hybrid nanowires. In these qubits, the spin degree of freedom is intrinsically coupled to the supercurrent across a Josephson junction via the spin-orbit interaction, which facilitates fast, high-fidelity spin readout using circuit quantum electrodynamics techniques. Moreover, this spin-supercurrent coupling has been predicted to facilitate inductive multi-qubit coupling. In this work, we demonstrate a strong supercurrent-mediated coupling between two distant Andreev spin qubits. This qubit-qubit interaction is of the longitudinal type and we show that it is both gate- and flux-tunable up to a coupling strength of 178 MHz. Finally, we find that the coupling can be switched off in-situ using a magnetic flux. Our results demonstrate that integrating microscopic spin states into a superconducting qubit architecture can combine the advantages of both semiconductors and superconducting circuits and pave the way to fast two-qubit gates between remote spins.
@article{arxiv.2307.15654,
title = {Strong tunable coupling between two distant superconducting spin qubits},
author = {Marta Pita-Vidal and Jaap J. Wesdorp and Lukas J. Splitthoff and Arno Bargerbos and Yu Liu and Leo P. Kouwenhoven and Christian Kraglund Andersen},
journal= {arXiv preprint arXiv:2307.15654},
year = {2024}
}