NAND gate response in a mesoscopic ring: An exact study

TL;DR

This paper theoretically demonstrates that a mesoscopic ring with magnetic flux can function as a NAND logic gate, showing how quantum interference effects produce the desired logical behavior.

Contribution

It provides an exact Green's function formalism analysis of NAND gate response in a mesoscopic ring, highlighting the role of magnetic flux and gate voltages in quantum logic operations.

Findings

High output current for mixed or low inputs at flux $rac{ ext{half flux quantum}}$

Clear NAND gate behavior demonstrated through conductance and current analysis

Potential application in quantum electronic logic gate design

Abstract

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.