  We propose a controllable way of tuning Fano resonances in open quantum dots
in the absence of magnetic field. A quantum dot can be modified by changing the
gate voltages that define the dot itself. An extra degree of freedom can be
introduced by means of a controllable repulsive perturbation, such as the one
induced by scanning a Atomic Force Microscope tip on a real sample. We
numerically investigate the coupling between localized states in the dot and
the continuum in the leads. The advantage of such position controllable
perturbation is the selective manipulation of the quantum dot states. We show
that this could be a feasible alternative to quantum dots in Aharonov-Bohm
interferometers as a Fano resonance tuning device.
