Conduction channels of an InAs-Al nanowire Josephson weak link.

Wepresent a quantitative characterization of an electrically tunable Josephson junction defined in an InAs nanowire proximitized by an epitaxially-grown superconducting Al shell. The gate-dependence of the number of conduction channels and of the set of transmission coefficients are extracted from the highly nonlinear current-voltage characteristics. Although the transmissions evolve nonmonotonically, the number of independent channels can be tuned, and configurations with a single quasi-ballistic channel achieved. [ABSTRACT FROM AUTHOR]