Microwave spectroscopy of interacting Andreev spins
Jaap J. Wesdorp, F. J. Matute-Cañadas, Arjen Vaartjes, Lukas Grünhaupt, T. Laeven, S. Roelofs, Lukas Johannes Splitthoff, Marta Pita‐Vidal, A. Bargerbos, David J. van Woerkom, Peter Krogstrup, Leo P. Kouwenhoven, Christian Kraglund Andersen, A. Levy Yeyati, Bernard van Heck, G. de Lange
Abstract
Andreev bound states are fermionic states localized in weak links between superconductors, which can be occupied with spinful quasiparticles. Recently, experiments embedding a nanowire Josephson junction into a superconducting circuit have enabled coherent manipulation of a single Andreev spin. However, these experiments remained limited to small magnetic fields. Here, the authors measure the microwave spectra of a nanowire Josephson junction in magnetic fields up to $\ensuremath{\sim}$ 250 mT and identify singlet, doublet, and triplet states of interacting Andreev spins.