Andreev Molecule in Parallel InAs Nanowires.
Coupling individual atoms fundamentally changes the state of matter: electrons bound to atomic cores become delocalized turning an insulating state to a metallic one. A chain of atoms could lead to more exotic states if the tunneling takes place via the superconducting vacuum and can induce topologically protected excitations like Majorana or parafermions. Although coupling a single atom to a superconductor is well studied, the hybridization of two sites with individual tunability was not reported yet. The peculiar vacuum of the Bardeen-Cooper-Schrieffer (BCS) condensate opens the way to annihilate or generate two electrons from the bulk resulting in a so-called Andreev molecular state. By employing parallel nanowires with an Al shell, two artificial atoms were created at a minimal distance with an epitaxial superconducting link between. Hybridization via the BCS vacuum was observed and the spectrum of an Andreev molecule as a function of level positions was explored for the first time.
['Kürtössy|Olivér|O|https://orcid.org/0000-0003-0221-403X', 'Scherübl|Zoltán|Z|', 'Fülöp|Gergö|G|', 'Lukács|István Endre|IE|', 'Kanne|Thomas|T|', 'Nygård|Jesper|J|', 'Makk|Péter|P|https://orcid.org/0000-0001-7637-4672', 'Csonka|Szabolcs|S|']
Andreev molecule nanowire superconductivity hybridization Yu-Shiba-Rusinov