XOR gate response in a mesoscopic ring with embedded quantum dots

TL;DR

This paper demonstrates how a mesoscopic quantum ring with embedded quantum dots can function as an XOR logic gate by controlling conductance through magnetic flux and gate voltages, showing potential for quantum electronic logic devices.

Contribution

It introduces a novel quantum device design that exhibits XOR logic behavior using a mesoscopic ring with quantum dots under magnetic flux.

Findings

XOR gate behavior observed at half flux quantum

High output current when exactly one input is high

Low output current when inputs are both high or both low

Abstract

We address XOR gate response in a mesoscopic ring threaded by a magnetic flux $\phi$. The ring, composed of identical quantum dots, is symmetrically attached to two semi-infinite one-dimensional metallic electrodes and two gate voltages, viz, $V_a$ and $V_b$, are applied, respectively, in each arm of the ring which are treated as the two inputs of the XOR gate. 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 ring-electrodes coupling strengths, magnetic flux and gate voltages. Quite interestingly it is observed 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, 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 behavior and this aspect may be utilized in designing the electronic logic gate.