  We propose a quantum pump mechanism based on the particular properties of
graphene, namely chirality and bipolarity. The underlying physics is the
excitation of evanescent modes entering a potential barrier from one lead,
while those from the other lead do not reach the driving region. This induces a
large nonequilibrium current with electrons stemming from a broad range of
energies, in contrast to the narrow resonances that govern the corresponding
effect in semiconductor heterostructures. Moreover, the pump mechanism in
graphene turns out to be robust, with a simple parameter dependence, which is
beneficial for applications. Numerical results from a Floquet scattering
formalism are complemented with analytical solutions for small to moderate
driving.
