Strong tunable coupling between two distant superconducting spin qubits

• DOI: 10.1038/s41567-024-02497-x
• Publication Date: 2024-05-06T10:02:12Z
• Authors: Marta Pita-Vidal; Jaap J. Wesdorp; Lukas J. Splitthoff; Arno Bargerbos; Yu Liu; Leo P. Kouwenhoven; Christian Kraglun...
• Keywords: Superconductivity (cond-mat.supr-con); Quantum Physics; Condensed Matter - Mesoscale and Nanoscale Physics; Condensed Matter - Superconductivity; Mesoscale and Nanoscale Physics (cond-mat.mes-hall); FOS: Physical sciences; Quantum Physics (quant-ph); 7. Clean energy

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.<br/>26 pages, 27 figures<br/>