Universal Landauer conductance in chiral symmetric two-dimensional systems

We study the transport properties of an arbitrarily shaped ultraclean graphene sheet, which is adiabatically connected to leads that are composed of the same material. If the localized interactions do not destroy the chiral symmetry, we show that the conductance is quantized, since it is dominated by the quasi-one-dimensional leads. As an example, we show that the smooth structural deformations of the graphene plane do not modify the conductance quantization.