High-Transparency Al/Bi 2 Te 3 Double-Barrier Heterostructures

We have fabricated highly transparent Al/Bi 2 Te 3 /Al superconductor/normal metal/superconductor double-barrier heterostructures. Transport measurements reveal the presence of multiple Andreev reflections related to two distinct energy gaps that we identify as the induced superconducting gap in the two electrodes. The realization of high-transparency Josephson junctions with topological insulators is an important step towards the study of topological superconductivity and Majorana fermions.