Origin of universal optical conductivity and optical stacking sequence identification in multilayer graphene.

We show that the origin of the universal optical conductivity in a normal N-layer graphene multilayer is an emergent chiral symmetry which guarantees that sigma(omega) = Nsigma_{uni} in both low and high-frequency limits. [sigma_{uni} = (pi/2)e;{2}/h]. We use this physics to relate intermediate frequency conductivity trends to qualitative characteristics of the multilayer stacking sequence.