  We study electron transport through a quantum interferometer with
side-coupled quantum dots. The interferometer, threaded by a magnetic flux
$\phi$, is attached symmetrically to two semi-infinite one-dimensional metallic
electrodes. The calculations are based on the tight-binding model and the
Green's function method, which numerically compute the conductance-energy and
current-voltage characteristics. Our results predict that under certain
conditions this particular geometry exhibits anti-resonant states. These states
are specific to the interferometric nature of the scattering and do not occur
in conventional one-dimensional scattering problems of potential barriers. Most
importantly we show that, such a simple geometric model can also be used as a
classical XOR gate, where the two gate voltages, viz, $V_a$ and $V_b$, are
applied, respectively, in the two dots those are treated as the two inputs of
the XOR gate. For $\phi=\phi_0/2$ ($\phi_0=ch/e$, the elementary flux-quantum),
a high output current (1) (in the logical sense) appears if one, and only one,
of the inputs to the gate is high (1), while if both inputs are low (0) or both
are high (1), a low output current (0) appears. It clearly demonstrates the XOR
gate behavior and this aspect may be utilized in designing the electronic logic
gate.
