Josephson Effect in a Few-Hole Quantum Dot.

Ridderbos, Joost; Brauns, Matthias; Shen, Jie; de Vries, Folkert K; Li, Ang; Bakkers, Erik P A M; Brinkman, Alexander; Zwanenburg, Floris A · Adv Mater · 2018

basic_science · Level V

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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.