title: Coulomb blockade and coherent single-cooper-pair tunneling in single Josephson junctions.
abstract: We have measured the current-voltage characteristics of small-capacitance single Josephson junctions at low temperatures ( T< or =0.04 K), where the strength of the coupling between the single junction and the electromagnetic environment was controlled with one-dimensional arrays of dc SQUIDs. We have clearly observed Coulomb blockade of Cooper-pair tunneling and even a region of negative differential resistance, when the zero-bias resistance of the SQUID arrays is much higher than the quantum resistance h/e(2) approximately 26 kOmega. The negative differential resistance is evidence of coherent single-Cooper-pair tunneling in the single Josephson junction.
authors.affiliation: Nanostructure Physics, The Royal Institute of Technology (KTH), Lindstedtsvägen 24, SE-100 44 Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Watanabe
authors.forename: D B
authors.initials: DB
authors.lastname: Haviland