  We theoretically study a current switch that exploits the phase acquired by a
charge carrier as it tunnels through a potential barrier in graphene. The
system acts as an interferometer based on an armchair graphene quantum ring,
where the phase difference between interfering electronic wave functions for
each path can be controlled by tuning either the height or the width of a
potential barrier in the ring arms. By varying the parameters of the potential
barriers the interference can become completely destructive. We demonstrate how
this interference effect can be used for developing a simple graphene-based
logic gate with high on/off ratio
