  Photocurrent generation is studied in a system composed of a quantum wire
with side-coupled quantum rings. The current generation results from the
interplay of the particular geometry of the system and the use of circularly
polarized radiation. We study the energy-momentum conservation for optical
transitions involving electrons moving forwards and backwards in the wire. Due
to the lack of time-reversal symmetry in the radiation, the optical transitions
depend on the direction of motion of the electrons, leading to a current at
zero bias voltage. The photocurrent increases with the number of rings within a
wide range of physical parameters. A weak non-linear dependence of the current
in the number of rings, related to quantum interference effects, is also
predicted. This geometry suggests a scalable method for the generation of
sizeable photocurrents based on nanoscale components.
