Conductivity in glass phases of disordered granular superconductors in magnetic fields

The electric conductivities in glass phases of three-dimensional (3D) granular superconductors in magnetic fields are examined based on a quantum disordered Josephson-junction array. A correct inclusion of the Ohmic dissipative dynamics leads to glass phases with divergent dc conductivity. In contrast, with no dissipative term, a metallic response in a glass phase is obtained irrespective of the range of correlation of quenched disorder, i.e., even in the so-called Bose-glass phase with experimentally vanishing resistivity.