arXiv:1306.6304 · Physical Review B
Thermally activated conductance in arrays of small Josephson junctions
J. Zimmer, Nicolas Vogt, A. Fiebig, Sergey Syzranov, Alexander V. Lukashenko, R. Schäfer, Hannes Rotzinger, Alexander Shnirman, Michael Marthaler, Alexey Vladimirovich Ustinov
Abstract
We present measurements of the temperature-dependent conductance for series arrays of small-capacitance superconducting quantum interference devices (SQUIDs). At low-bias voltages, the arrays exhibit a strong Coulomb blockade, which we study in detail as a function of temperature and Josephson energy ${E}_{J}$. We find that the zero-bias conductance is dominated by a thermally activated hopping of Cooper pairs between neighboring superconductive islands with the activation energy of the order of $\ensuremath{\Lambda}{E}_{C}$, where $\ensuremath{\Lambda}$ is the charge screening length in the array and ${E}_{C}$ is the charging energy of a single SQUID.