  We explore the chiral transmission of electrons across graphene
heterojunctions for electronic switching using gate geometry alone. A sequence
of gates is used to collimate and orthogonalize the chiral transmission lobes
across multiple junctions, resulting in negligible overall current. The
resistance of the device is enhanced by several orders of magnitude by biasing
the gates into the bipolar $npn$ doping regime, as the ON state in the near
homogeneous $nn^-n$ regime remains highly conductive. The mobility is preserved
because the switching involves a transmission gap instead of a structural
band-gap that would reduce the number of available channels of conduction.
Under certain conditions this transmission gap is highly gate tunable, allowing
a subthermal turn-on that beats the Landauer bound on switching energy limiting
present day digital electronics.
