Quantum transport in a mesoscopic ring: Evidence of an OR gate

We explore OR gate response in a mesoscopic ring threaded by a magnetic flux $\phi$. The ring is symmetrically attached to two semi-infinite one-dimensional metallic electrodes and two gate voltages, viz, $V_a$ and $V_b$, are applied in one arm of the ring which are treated as the two inputs of the OR gate. All 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 as functions of the gate voltages, ring-to-electrodes coupling strengths 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 high (1), while if neither input is high (1), a low output current (0) appears. It clearly demonstrates the OR gate behavior and this aspect may be utilized in designing the electronic logic gate.