  The superfluid phase and Coulomb drag effect caused by the pairing in the
system of spatially separated electrons and holes in two coaxial cylindrical
nanotubes are predicted. It is found that the drag resistance as a function of
temperature experiences a jump at the critical temperature and can be used for
the manifestation of the superfluid transition. It is demonstrated that at
sufficiently low temperatures the order parameter and free energy density
exhibit a kink due to the electron-hole asymmetry that is controlled by the
radii of the nanotubes.
