The spectrum of a segment of InAs nanowire, confined between two
superconducting leads, was measured as function of gate voltage and
superconducting phase difference using a third normal-metal tunnel probe.
Sub-gap resonances for odd electron occupancy---interpreted as bound states
involving a confined electron and a quasiparticle from the superconducting
leads, reminiscent of Yu-Shiba-Rusinov states---evolve into Kondo-related
resonances at higher magnetic fields. An additional zero bias peak of unknown
origin is observed to coexist with the quasiparticle bound states.Comment: Supplementary information available here:
https://dl.dropbox.com/u/1742676/Chang_Sup.pd
