  Within the t-J model, we study the charge transport in underdoped bilayer
cuprates by considering the bilayer interaction. Although the bilayer
interaction leads to the band splitting in the electronic structure, the
qualitative behavior of the charge transport is the same as in the case of
single layer cuprates. The conductivity spectrum shows a low-energy peak and
the unusual midinfrared band. This midinfrared band is suppressed severely with
increasing temperatures, while the resistivity in the heavily underdoped regime
is characterized by a crossover from the high temperature metallic-like to the
low temperature insulating-like behaviors, which are consistent with the
experiments.
