  NAND gate response in a mesoscopic ring threaded with a magnetic flux $\phi$
is investigated by using Green's function formalism. The ring is attached
symmetrically to two semi-infinite one-dimensional metallic electrodes and two
gate voltages, namely, $V_a$ and $V_b$, are applied in one arm of the ring
those are treated as the two inputs of the NAND gate. We use a simple
tight-binding model to describe the system and numerically compute the
conductance-energy and current-voltage characteristics as functions of the gate
voltages, ring-to-electrode coupling strength and magnetic flux. Our
theoretical study shows that, 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 or both the inputs to the gate are low (0), while if both the
inputs to the gate are high (1), a low output current (0) appears. It clearly
exhibits the NAND gate behavior and this feature may be utilized in designing
an electronic logic gate.
