  The mechanisms of optical activity and quantum transport of twisted bilayer
graphene are studied. The formation of unique electron states in the bilayer
systems is studied using an effective continuum model. Such states are shown to
support the correlation of transverse motions of electrons in two graphene
layers. Because of the chiral structure of the atomic lattices, the
contribution of such drag correlations is incompletely cancelled, thus
resulting in a drag term of the optical conductivity tensor. We show that the
drag term of the conductivity is the manifestation of the spatial dispersion.
We show how to analyze and calculate the components of the conductivity tensors
that governs the optical activity of the systems. The DC conductivity of the
twisted bilayer graphene system is also calculated. It shows the existence of a
quantum conductivity value $\propto e^2/h$ at the intrinsic Fermi energy.
