Nanotubes and microtubules as quantum information carriers

In the foreseeable future silicon based electronics will reach limits in miniaturization and switching speeds, imposed by fundamental physical constraints. The quest for smaller gates and higher processing speeds with the attendant increase of chip functional density will reach the point where quantum effects dominate. Alternative strategies will then be required to overcome the limitations of silicon; among the most promising are those exploiting the properties of biological molecules, notably microtubules. These have the advantages associated with carbon chemistry, including the scope for constructing large highly complex macromolecular assemblies, and share the exciting electronic properties of semi- and superconductors. Biological systems have the potential to bypass the limiting effects of single particle quantum systems through the interactions of complex molecules, necessarily based on hydrocarbon polymers.