  We study the response of exciton complexes in semiconductor quantum rings to
vertical electric fields, using path integral quantum Monte Carlo simulations.
The interaction of a vertical applied field and the piezoelectric fields of the
ring with strongly-correlated excitonic complexes switches excitons between two
different lateral locations within the ring. This control should be observable
through polarizability and dipole measurements, and, for biexcitons, an energy
shift beyond the normal Stark shift.
