Electron Transport in Carbon Nanotubes with Superconducting Contacts

We report on our measurements of electron conductance in single-walled carbon nanotubes contacted by superconducting leads. We study the proximity effect induced by the superconducting contacts at temperatures below the transition temperature of the leads. Excess differential conductance (way above the ballistic limit of $4e^2/h$ for a single-wall nanotube with normal contacts) and sub-gap Andreev reflection peaks are observed.