  Controlling the properties of materials by driving them out of equilibrium is
an exciting prospect that has only recently begun to be explored. In this paper
we give a striking theoretical example of such materials design: a tunable gap
in monolayer graphene is generated by exciting a particular optical phonon. We
show that the system reaches a steady state whose transport properties are the
same as if the system had a static electronic gap, controllable by the driving
amplitude. Moreover, the steady state displays topological phenomena: there are
chiral edge currents, which circulate a fractional charge e/2 per rotation
cycle, with frequency set by the optical phonon frequency.
