title: Gate-tunable dissipation and "superconductor-insulator" transition in carbon nanotube josephson junctions.
abstract: Dissipation is ubiquitous in quantum systems, and its interplay with fluctuations is critical to maintaining quantum coherence. We experimentally investigate the dissipation dynamics in single-walled carbon nanotubes coupled to superconductors. The voltage-current characteristics display gate-tunable hysteresis, with sizes that perfectly correlate with the normal state resistance R_{N}, indicating the junction undergoes a periodic modulation between the underdamped and overdamped regimes. Surprisingly, when a device's Fermi level is tuned through a local conductance minimum, we observe a gate-controlled transition from superconductinglike to insulatinglike states, with a "critical" R_{N} value approximately 8-20 kOmega.
authors.affiliation: Department of Physics and Astronomy, University of California, Riverside, Riverside, California 92521, USA.
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Chun Ning
authors.initials: CN
authors.lastname: Lau