Ballistic transmission through a graphene bilayer

We calculate the Fermi energy dependence of the (time-averaged) current and shot noise in an impurity-free carbon bilayer (length $L⪡\text{width}$ $W$), and compare with known results for a monolayer. At the Dirac point of charge neutrality, the bilayer transmits as two independent monolayers in parallel: Both current and noise are resonant at twice the monolayer value, so that their ratio (the Fano factor) has the same $1∕3$ value as in a monolayer—and the same value as in a diffusive metal. The range of Fermi energies around the Dirac point within which this pseudodiffusive result holds is smaller, however, in a bilayer than in a monolayer (by a factor $l_{\perp }∕L$, with $l_{\perp }$ the interlayer coupling length).