  The in-plane DC conductivity of twisted bilayer graphene (TBLG) is calculated
using an expansion of the real-space Kubo-Bastin conductivity in terms of
Chebyshev polynomials. We investigate within a tight-binding (TB) approach the
transport properties as a function of rotation angle, applied perpendicular
electric field and vacancy disorder. We find that for high-angle twists, the
two layers are effectively decoupled, and the minimum conductivity at the Dirac
point corresponds to double the value observed in monolayer graphene. This
remains valid even in the presence of vacancies, hinting that chiral symmetry
is still preserved. On the contrary, for low twist angles, the conductivity at
the Dirac point depends on the twist angle and is not protected in the presence
of disorder. Furthermore, for low angles and in the presence of an applied
electric field, we find that the chiral boundary states emerging between AB and
BA regions contribute to the DC conductivity, despite the appearance of
strongly localized states in the AA regions. The results agree with recent
conductivity experiments on twisted bilayer graphene.
