Electron transport through a quantum interferometer with side-coupled quantum dots: Green's function approach

TL;DR

This paper investigates electron transport in a quantum interferometer with side-coupled quantum dots using Green's function methods, revealing anti-resonant states and demonstrating its potential as a classical XOR logic gate.

Contribution

It introduces a novel geometric model for quantum interference and demonstrates its application as an XOR logic gate using magnetic flux and gate voltages.

Findings

Identification of anti-resonant states unique to the interferometric geometry.

Demonstration of XOR gate behavior with specific magnetic flux conditions.

Potential application in designing electronic logic gates.

Abstract

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.