Nonuniversal Shot Noise in Disordered Quantum Wires with Channel-Number Imbalance

TL;DR

This paper investigates how channel-number imbalance in disordered quantum wires, such as graphene nanoribbons, leads to nonuniversal shot noise behavior, deviating from the typical one-third suppression seen in ordinary conductors.

Contribution

It introduces a model to control channel imbalance and calculates shot noise, revealing the breakdown of universal suppression in nonuniform quantum wires.

Findings

Shot noise deviates from one-third suppression with increasing channel imbalance.

Channel imbalance causes highly nonuniversal shot noise behavior.

The model demonstrates controllable transition from universal to nonuniversal shot noise regimes.

Abstract

The number of conducting channels for one propagating direction is equal to that for the other direction in ordinary quantum wires. However, they can be imbalanced in graphene nanoribbons with zigzag edges. Employing the model system in which a degree of channel-number imbalance can be controlled, we calculate the shot-noise power at zero frequency by using the Boltzmann-Langevin approach. The shot-noise power in an ordinary diffusive conductor is one-third of the Poisson value. We show that with increasing the degree of channel-number imbalance, the universal one-third suppression breaks down and a highly nonuniversal behavior of shot noise appears.