Tunneling spectroscopy in carbon nanotubes

Carbon nanotubes are one-dimensional metallic or semiconducting wires that serve as good model systems to study Luttinger liquids, in which electron-electron interaction are essential to electronic transport. Luttinger behavior has previously been measured via transport through the ends of nanotubes. We have fabricated novel nanotube devices with three-terminal configurations---two normal contacts at the ends and one non-invasive superconducting tunnel probe in the middle. This configuration is well-suited to tunnel spectroscopy studies of bias-dependence, non-equilibrium effects, and carrier interactions in nanotubes. We present results on low-temperature tunneling measurements performed using this configuration.