Josephson Effect in a Few-Hole Quantum Dot
Joost Ridderbos (University of Twente)
Matthias Brauns (Institute of Science and Technology Austria, University of Twente)
Jie Shen (TU Delft - QRD/Kouwenhoven Lab)
Folkert K. de Vries (TU Delft - QRD/Kouwenhoven Lab)
Ang Li (Beijing University of Technology, Eindhoven University of Technology)
Erik P.A.M. Bakkers (TU Delft - QN/Bakkers Lab, Eindhoven University of Technology)
Alexander Brinkman (University of Twente)
Floris A. Zwanenburg (University of Twente)
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Abstract
A Ge–Si core–shell nanowire is used to realize a Josephson field-effect transistor with highly transparent contacts to superconducting leads. By changing the electric field, access to two distinct regimes, not combined before in a single device, is gained: in the accumulation mode the device is highly transparent and the supercurrent is carried by multiple subbands, while near depletion, the supercurrent is carried by single-particle levels of a strongly coupled quantum dot operating in the few-hole regime. These results establish Ge–Si nanowires as an important platform for hybrid superconductor–semiconductor physics and Majorana fermions.