title: Terahertz Field Enhancement and Photon-Assisted Tunneling in Single-Molecule Transistors.
abstract: We have investigated the electron transport in single-C_{60}-molecule transistors under the illumination of intense monochromatic terahertz (THz) radiation. By employing an antenna structure with a sub-nm-wide gap, we concentrate THz radiation beyond the diffraction limit and focus it onto a single molecule. Photon-assisted tunneling (PAT) in the single molecule transistors is observed in both the weak-coupling and Kondo regimes. The THz power dependence of the PAT conductance indicates that when the incident THz intensity is a few tens of mW, the THz field induced at the molecule exceeds 100  kV/cm, which is enhanced by a factor of ~10^{5} from the field in the free space.
authors.affiliation: Center for Photonics Electronics Convergence, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Center for Photonics Electronics Convergence, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.|Institute for Nano Quantum Information Electronics, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Shibata
authors.affiliation: Center for Photonics Electronics Convergence, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.|Institute for Nano Quantum Information Electronics, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Hirakawa