  Coulomb drag and depinning are electronic transport phenomena that occur in
low-dimensional nanostructures. Recently, both phenomena have been reported in
bilinear Josephson junction arrays. These devices provide a unique opportunity
to study the interplay of Coulomb drag and depinning in a system where all
relevant parameters can be controlled experimentally. We explain the Coulomb
drag and depinning characteristics in the I-V curve of the bilinear Josephson
junction array by adopting a quasicharge model which has previously proven
useful in describing threshold phenomena in linear Josephson junction arrays.
Simulations are performed for a range of coupling strengths, where numerically
obtained I-V curves match well with what has been previously observed
experimentally. Analytic expressions for the ratio between the active and
passive currents are derived from depinning arguments. Novel phenomena are
predicted at voltages higher than those for which experimental results have
been reported to date.

Mesoscale and Nanoscale Physics;Superconductivity