Microscopic theory of Cooper pair beam splitters based on carbon   nanotubes
  We analyze microscopically a Cooper pair splitting device in which a central superconducting lead is connected to two weakly coupled normal leads through a carbon nanotube. We determine the splitting efficiency at resonance in terms of geometrical and material parameters, including the effect of spin-orbit scattering. While the efficiency in the linear regime is limited to 50% and decay exponentially as a function of the width of the superconducting region we show that it can rise up to $\sim 100%$ in the non-linear regime for certain regions of the stability diagram. 
P. Burset, W. J. Herrera and A. Levy Yeyati
cond-mat.mes-hall cond-mat.supr-con