Doppler shift in Andreev reflection from a moving superconducting condensate in Nb/InAs Josephson junctions

Abstract

We study narrow ballistic Josephson weak links in an InAs quantum well contacted by Nb electrodes. Measurements of the conductance, excess and critical currents reveal a dramatic magnetic-field suppression of the Andreev reflection amplitude, which occurs even for in-plane field orientation with essentially no magnetic flux through the junction. Our observations demonstrate the presence of an additional energy scale in the spectrum of the hybrid Nb/InAs-banks and the effect of screening currents in them.